200933202 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 示器之背光板模組、照明裝置等之光擴散性聚酯薄膜。更 詳言之，係有關於一種兼顧光擴散性及光線透射率且伴隨 著溫度變化所產生的卷曲小之表面光擴散性聚酯薄膜。 【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、行動電話等之顯示裝置。特別是近年 來在液晶顯示器的各種用途，高精細化正進展中，特別是 在電視用途，伴隨著高畫質（highvisipn)廣播的普及，先前 以在大畫面液晶顯示器的採用爲中心之橫向1 920X縱向 1 0 8 0點亦即能夠全高畫質（full HD)顯示之液晶顯示器亦逐 漸地被採用於比較小型畫面尺寸的液晶顯示器，且高精細 化的要求係越來越高。因爲液晶顯示單元單獨時該等液晶 顯示器係未具有發光功能，必須在其背面設置背光板模組 ® 才能夠顯示。 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TV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 200933202 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 電力小、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被要求薄型化、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 ❹ 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 反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 〇 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膜、或透鏡薄膜之具有聚光 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棱鏡狀或波長、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。此種稜鏡薄膜係在前述 擴散性薄膜的表面側配設1片或重疊2片而使用。 而且，爲了使配設上述稜鏡薄片所產生的亮度不均或 200933202 稜鏡薄片的缺陷不顯著化（提高遮蔽性），亦有在稜鏡薄片 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 構成之光擴散層而得到者（例如參照專利文獻1、2)爲主流。 專利文獻1 :特開平6 - 5 9 1 0 8號公報 專利文獻2:特許第3698978號說明書 但是因爲該法時必須在基材薄膜的一面藉由塗布來設 ❹ 置光擴散層，會有因光擴散層與基材薄膜的線膨脹係數不 同’光擴散性薄膜成爲雙金屬狀的結構、或是容易因加熱 而產生卷曲的問題。該問題特別是在近年來大型液晶TV 等採用大型且必須高亮度的正下方型背光板模組之液晶顯 示器’逐漸成爲重要問題。因爲光擴散性薄膜越大面積化 時，卷曲變爲越顯著’而且，因爲液晶顯示器越高亮度化 時’光源的消耗電力、亦即背光板模組的發熱量越大。 爲了解決此問題，必須謀求消除雙金屬狀。通常在基 Ο 材薄膜的光擴散層表面，係形成有數微米至數十微米厚度 之硬塗層（非光擴散層），係採用夾住光擴散層的兩面來使 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，使光擴散性 薄膜增加不需要的厚度時，會成爲造成製造成本增加的原 因。而且，使表背的線膨脹應力平衡的對策亦有其限度， 在如上述之大畫面、高亮度顯示器，只能夠得到不充分的 效果。 又’近年來，爲了使背光板模組組件數目減少、或製 200933202 程的簡略化、低成本化之目的，亦進行許多將光擴散性薄 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3)，其特徵係 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)，其特徵係在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，而該棱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棱鏡形狀而成。 而且，有揭示一種棱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 73225 3號說明書 φ 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。 200933202 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 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，能夠解決前述加熱卷曲的問題、或亦能夠打開使擴散 薄片與稜鏡薄膜功能整體化的途徑，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 G 具有的某種特長（耐熱性、機械強度等），或是損害光線透 射率或所謂光擴散性之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 〇 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 線透射率最高者亦只有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。 200933202 專利文獻6:特開2001-272508號公報 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 兀聚合物）與光擴散層的構成樹脂（非晶性聚醋）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卷曲。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） 而產生卷曲之情形。 又，有揭示一種薄膜（參照專利文獻7〜13)，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。 〇 專利文獻7 :特開200 1 -324606號公報 專利文獻8:特開2002-162508號公報 專利文獻9:特開2002-182013號公報 專利文獻10:特開2002-196113號公報 專利文獻11:特開2002-372606號公報 專利文獻12:特開20 04-2 1 943 8號公報 專利文獻13:特開2004-354558號公報 因爲此等方法係因爲薄膜結構成爲表背對象，雖然對 結構所產生的卷曲能夠得到某種程度的改善。但是在光擴 -10- 200933202 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14)，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2002-37898號公報 在專利文獻14，於實施例掲示一種薄膜，係使用聚對 酞酸乙二酯作爲聚酯的原料，且具有8 8%的總光線透射率 及6 8%的擴散透射率。而且，揭示一種具有8 5 %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 Φ 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2 00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9.0 倍拉伸而得到的薄膜，其厚度爲50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4.〇倍。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 且’實際的面積拉伸倍率爲4倍左右的拉伸，即便能夠得 -11 - 200933202 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。 如上述，因爲雙金屬狀的薄膜基材伴隨著液晶顯示器 用背光板模組的大型化、高輸出功率化，容易產生卷曲的 問題會逐漸地顯在化，爲了解決上述問題，以不使用離線 塗布的方法而使用實際拉伸薄膜本身爲佳（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，有無 法避免因光擴散性粒子所產生的空隙，且總光線透射率低 G 落之問題（專利文獻3、4、5)。避免產生空隙之方法，先前 使用之樹脂性狀或拉伸條件時卷曲的問題無法解決（專利 文獻6)，或是有薄膜的,,力學強度低落之問題（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有 矛盾的關係，無法得到任一者的特性都能夠滿足之薄膜。 因此，在綜合品質達不到藉由後加工在透明基材薄膜賦予 後加工之先前的方法，上述方法尙未達到實用化。 鑒於上述的課題，本發明者等在先前已進行先前申請 〇 發明（1)(特願2007- 1 91 907號），其目的係提供一種表面光 擴散性聚酯薄膜，其具有雙軸配向聚酯薄膜本來的優良耐 熱性、機械強度及厚度精確度等，且能夠兼顧總光線透射 率及光擴散性，且能夠抑制來自雙金屬結構之產生加熱卷 曲。 先前申請發明（I)係提供一種表面光擴散性聚酯薄膜， 其能夠抑制因加熱所產生的卷曲，且具有雙軸配向聚酯薄 膜本來優良的力學特性，而且能夠兼顧總光線透射率及光 擴散性。爲了謀求能夠兼顧上述特性，本發明者等特別著 -12- 200933202 眼於薄膜的面配向係數、內部霧度及表面霧度之關係，並 進行專心硏討。結果本發明者等發現藉由採用後述[1]〜[7] 所述之手段，能夠兼顧矛盾的特性，而完成了先前申請發 明（I)。 【發明內容】 發明所欲解決之課題 因爲先前申請發明（I)的表面光擴散性聚酯薄膜之支撐 層及光擴散層係任一者均是由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結構所產生的加熱卷 曲，同時具有雙軸配向聚酯薄膜本來的優良耐熱性、機械 強度及厚度精確度。 又，因爲先前申請發明（I)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， 而且薄膜整體的面配向係數被控制在特定範圍內，所以在 添加於光擴散層中之非相溶性的添加劑之周圍，實質上不 會產生空隙且在光擴散層表面具有凹凸結構。因此，能夠 〇 兼具優良的表面光擴散性及高光線透射率。 硏討先前申請發明（I)之表面光擴散性聚酯薄膜的各種 利用形態，結果清楚明白特別是在高精細化、高亮度已進 展之全高畫質（full HD)型的液晶顯示器，在與光擴散薄膜 組合之透鏡薄片或稜鏡薄片的形狀或間距及其他方面所施 加之各式各樣的功夫。又，高精細的液晶顯示器時像素間 距變爲非常小。本發明的目的係提供一種表面光擴散性聚 酯薄膜’其能夠以廣闊範圍的利用形態活用先前申請發明 (I)的表面光擴散性聚酯薄膜的優良特性，特別是與各式各 -13- 200933202 樣的透鏡薄片或稜鏡薄片、液晶面板組合來顯示優良的顯 示特性。 解決課題之手段 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)〜（6)。 © (1)具有支撐層及光擴散層，該支撐層係由含有結晶性同元 聚酯、或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235〜2 55 °C的共聚合成分之結晶 性聚酯及與該聚酯爲非相溶性的1〜50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AP爲0.08〜0.16， Δ P=(nx+ny)/2-nz φ 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lOOMPa以上。 (6) 由下述式所定義之表示薄膜的光擴散性S(3)爲30%以 上、小於5 0 %， S(3) = I(3)/I(0)x 100 -14 - 200933202 在此，1(3)、1(0)係各自表示透射光強度之中，擴散角 度爲3度的値及0度的値。 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8 6 %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 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 G 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 本發明的表面光擴散性聚酯薄膜除了在先前申請發明 (I)已達成能夠抑制因加熱所產生的卷曲，且具有雙軸配向 聚酯薄膜本來優良的力學特性，而且能夠解決兼顧總光線 透射率及光擴散性之矛質課題以外，進而藉由實現經改良 的表面凹凸結構，在使用與於各式各樣的透鏡薄片或稜鏡 -15- 200933202 薄片、液晶面板組合使用時亦能夠實現能夠防止所謂波紋 或閃爍之顯示品質低落之效果。 【實施方式】 本發明係提供一種表面光擴散性聚酯薄膜，其能夠抑 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，而且兼顧總光線透射率及光擴散性，並且 與各式各樣的透鏡薄片或稜鏡薄片、液晶面板組合而使用 時，亦具有能夠防止波紋或被稱爲閃爍的顏色閃爍之顯示 Ο 品質低落之效果。爲了謀求實現上述特性，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，並且亦著眼於光擴散層的表面凹凸結構，而進行專心 硏討。結果發現藉由採用下述（1)〜（8)所敘述的手段，能夠 實現如此的特性，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)~(8)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)~( 8)的手段才能夠實現上述特性。 〇 (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 (8) 光擴散層的表面凹凸結構的控制 (1)光擴散層（B )之樹脂熔點的控制 -16- 200933202 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 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 Ο 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 〇 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 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 t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。 -17- 200933202 (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 聚醋或含有共聚合成分之結晶性聚酯所構成的支撐層 (A)°爲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 卷曲。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 t以 內爲佳，以2 0 °C以內爲較佳，以1 〇 °C以內爲更佳，以5 °C以內爲特佳。熔點差異，爲25 °C以內時，雙金屬狀結構 所產生的卷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 〇 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，能夠兼顧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、或甘醇成分全 體，以3莫耳％以上爲佳，以5莫耳％以上爲更佳，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， -18- 200933202 因爲能夠抑制產生空隙，且容易高度地兼顧光線透射率及 光擴散性’乃是較佳。另一方面，共聚合成分的導入量的 上限係相對於上述成分以2 0莫耳％以下爲佳，以1 8莫耳％ 以下爲更佳，以1 5莫耳％以下爲特佳。使共聚合成分爲2〇 莫耳％以下時，因爲雙金屬狀結構所產生的卷曲能夠抑制 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 〇 霧度。空隙等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，表面結構引起之光 的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卷曲係困難的。 本發明藉由採用（1)至（7)所揭示的手段’能夠提供一種能夠 抑制產生卷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 -19- 200933202 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 Ο 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稜鏡薄片疊合 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 〇 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 以上爲更佳，以5微米以上爲特佳。 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。 -20- 200933202 因此，若使光擴散層（B)的厚度較厚時，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)的厚度的上限以50微米爲佳，以30微米 爲更佳，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卷曲變爲容易。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 φ 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 的，所以異物所引起的光學缺點以較少爲佳，藉由共擠壓 -21 - 200933202 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， 〇 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0.5 0dl/g爲佳，以 0.52dl/g爲更佳。固有黏度小於0.50dl/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 以 〇.61dI/g爲佳，以 0.59dl/g爲更佳。固有黏度大於 0.6 ldl/g時，前述添加劑在聚酯中的分散徑變小，光擴散 -22- 200933202 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 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，該結晶性聚酯的溶融黏度與該 添加劑的熔融黏度係同程度時，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。該熔融黏度差異以35Pa . s以上爲佳，以40Pa · s以 上爲更佳。熔融黏度差異爲35Pa· s以上時，添加劑在聚 φ 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 地藉由非相溶性的添加劑來形成表面凹凸，從兼顧總光線 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， -23- 200933202 熱尺寸變化率亦降低，在熱處理時不容易產生卷曲。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、及兼顧總光 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 〇 膜時，其橫向拉伸時的溫度以120°C至16(TC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 235至250 °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。 (8)光擴散層的表面凹凸結構的控制 先前申請發明（I)的光擴散性聚酯薄膜係藉由上述手段 〇 (1)〜（7)互相關聯來達成。但是在近年來，液晶顯示器的高 精細化、高亮度等的高功能化當中，亦盛行變更、改良與 光擴散性聚酯薄膜組合之透鏡薄片或稜鏡薄片 '液晶面板 的規格，要求光擴散性聚酯薄膜在與該等構件的各式各樣 組合能夠維持優良的顯示特性。 在藉由組合光擴散性聚酯薄膜與透鏡薄片或稜鏡薄 片、液晶面板之各種使用形態，在顯示性能經常成爲問題 的是波紋或閃爍。認爲光擴散性聚酯薄膜成爲原因之波 紋，係因爲在透射光擴散性聚酯薄膜而射出的光線有明暗 -24- 200933202 不均亦即配光不均，而且若其配向不均具有周期性時，其 周期性的間距與透鏡薄片的透鏡圖案或稜鏡薄片的稜鏡圖 案、液晶面板的像素等的周期結構的間距產生干擾而產生 的。又，認爲閃爍係因爲光擴散性聚酯薄膜的配光不均與 組入液晶面板之彩色濾光片的顏色像素的一部分重疊，致 使顏色像素的亮度產生變化而產生的。預料波紋或閃爍之 問題伴隨著液晶顯示器的高精細化、高亮度，且透鏡圖案、 稜鏡圖案、液晶面板的像素變小而容易變爲更顯著。認爲 φ 即便在先前申請發明（I)之表面光擴散性聚酯薄膜，依照所 組合的透鏡薄片或稜鏡薄片、液晶面板，亦由於配光不均 而有產生波紋或閃爍之可能性。 在表面光擴散性聚酯薄膜之配光不均係由於光擴散層 表面的凹凸結構不均而產生。在先前申請發明（I)，構成光 擴散層（B)之基材聚合物與非相溶性的添加劑係在擠壓機 內被攪拌混合。在此種製法，在擠壓機內攪拌混合基材聚 合物與非相溶性的添加劑時，若無法進行充分的攪拌混合 Q 來使添加劑粒子的分散狀態、分布狀態均勻化時，或是進 而因添加劑粒子的再凝聚而造成粒徑增大的不均勻，會有 產生難以會聚成爲均勻的粒徑之情況。拉伸、熱處理含有 此種不均勻的添加劑粒子之光擴散層（B)之薄膜時，由於在 光擴散層內之添加劑粒，容易產生分布狀態不均勻或粒徑 不均勻，光擴散層表面的凹凸結構容易產生不均勻。 鑒於上述情形，在採用上述（1)〜（7)的對策之同時，進 而專心硏討亦能夠防止如上述之光擴散層（B)中的添加劑 粒子不均勻的對策，結果達成了藉由以下的方法來解決之 -25- 200933202 對策。亦即，預先使用擠壓機將構成光擴散層（B)之基材聚 合物的全部或一部分與非相溶性的添加劑熔融混合來製成 預混煉母顆粒，進而使用擠壓機攪拌混合該預混煉母顆粒 (及殘留的基材聚合物）並與基材層（A)層積共擠出而形成 薄膜。在如此進行所形成之薄膜的光擴散層（B)，非相溶性 添加劑與先前申請發明（I)比較時，係均勻地分散在基材聚 合物中且其粒徑的均勻性比先前申請發明（I)優良。因此， 藉由將該薄膜拉伸、熱處理，能夠在該光擴散層（B)表面形 ® 成凹凸結構不連續或所謂起伏的不均較少之均勻的凹凸結 構。在與上述（1)〜（7)的條件控制之組合，光擴散層（B)的 表面凹凸結構的均勻度係反映在表面光擴散性聚酯薄膜的 光擴散特性。本發明的表面光擴散性聚酯薄膜之下述式所 示之光擴散性S(3)爲30%以上、小於50%。使用S(3)爲該 範圍的光擴散性聚酯薄膜作爲液晶顯示器的擴散薄膜時， 在與透鏡薄片或稜鏡薄片、液晶面板之各式各樣的組合， 能夠抑制產生所謂波紋或閃爍之問題。S(3)小於30%時， 〇 由於表面凹凸結構的不均，依照所使用透鏡薄片或稜鏡薄 片、液晶面板之組合，會產生波紋或閃爍，乃是不佳。s(3) 大於50%時，1(0)對1(3)的相對値必然性地變小，結果在背 光板模組的正面亮度低落，乃是不佳。 S(3)=I(3)/I(0)x100 在此，1(3)、1(0)係各自表示透射光強度之中，擴散角 度爲±3度的値及0度的値。 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。 -26- 200933202 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 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。 〇 爲了達成如申請專利範圍第1項之必要條件（6)，能夠 藉由實施上述手段（1)〜（8)的條件控制來達成。 在本發明，認爲上述（1)~(8)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 卷曲之方法。上述說明係揭示在高度地兼顧光線透射率及 0 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 °(：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) -27- 200933202 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 狀結構所產生的卷曲而成之表面光擴散性聚酯薄膜。 又，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。 〇 亦即，即便含有構成光擴散層（B)樹脂層的共聚合成分 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 φ 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 -28- 200933202 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，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 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、1，4-丁二醇、新戊二醇等甘醇進 行縮聚所製造的聚酯。該等聚酯除了能夠藉由使芳香族二 羧酸與甘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院酯與甘醇進行酯交換反應 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 〇 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 -29- 200933202 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 的共聚合聚酯爲佳。 分枝狀脂肪族甘醇係例如可例示新戊二醇、1,2-丙二 醇、1，2-丁二醇。又，脂環族甘醇可例示1，4-環己烷二甲醇、 三環癸烷二羥甲基等。 ❹ 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顧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下述的二羧酸成分 〇 及/或二醇成分之1種或2種以上作爲共聚合成分來倂用。 能夠與對酞酸或是其酯形成性衍生物一同並用之其他 的二羧酸成分可舉出（1)異對酞酸、2,6-萘二羧酸、二苯基 -4，4’-二羧酸、二苯氧基乙烷二羧酸 '二苯基碾二羧酸、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 丁烯二酸、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 •30- 200933202 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 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、三甘醇及二聚物二醇等。 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。 〇 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、錳化合物、鈷化合物、鋁化合物、銻化合 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。前述磷化合物係例如以磷酸、亞磷酸等爲佳。 本發明的表面光擴散性聚酯薄膜可以將前述共聚合聚 〇 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，採用溶融混合不同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） -31 - 200933202 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 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，藉由使用無不純物、潔淨的聚 酯原料，在液晶顯示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 〇的方向折射、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 -32 - 200933202 術。藉由使用該技術，在薄膜的熔融、擠壓製程藉由高精 度的過濾器來過濾異物，作爲液晶顯示器用薄膜能夠達成 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，高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，高度地兼顧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、非規聚苯乙烯、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 Φ 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 -33- 200933202 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、Μ PA 100型），從30 °C至350 °C以1〇 °C/分鐘升溫時， 不會因熔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35(TC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0.1〜50微米 爲佳。上述非熔融性聚合物粒子的平均粒徑的下限以〇.5 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」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30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50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 尖銳的粒子分布之粒子爲佳。 -34 - 200933202 上述非熔融性聚合物粒子可使用1種類’亦可使用2 種類以上。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，在薄膜中所 含有的粒子係單獨時，係測定各個粒子的最大庳徑，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0.1〜50微米爲佳。以 e 0.5〜30微米爲較-，以1~20微米爲更佳。平均粒徑小於 0.1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。 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 -35- 200933202 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，測定薄 膜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，醋薄膜之光擴散層，係由 50~99質量份含有前述共聚合成分之結晶性聚酯及1〜50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80~97質量份聚酯與3~20質量份添加 劑之調配。 Ο 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/聚酯界面的光散射增大，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 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] -36- 200933202 (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（ΔΡ) 爲0.08〜0.16係重要的。面配向係數（AP)的下限以〇.〇9爲 較佳，以〇_ 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（△ P)大於〇 · 1 6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（A P)爲0.1 6 以下時，能夠謀求兼顧總光線透射率與光擴散性。 另一方面，面配向係數爲0.08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，且能夠抑制加熱卷曲的產生。 ❹ 將面配向係數控制在上述範圍內之方法係任意，例如 能夠藉由調整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 合成分的比率時，能夠使面配向係數上升。較佳的共聚合 成分比率係如前述。 又，藉由聚合物摻合、或是共聚合來控制含有前述共 聚合成分之結晶性聚酯的玻璃轉移點亦無妨。使玻璃轉移 點降低時，在後述的雙軸拉伸製程的配向降低，能夠使面 -37- 200933202 配向係數降低。又，使光擴散層所使用原料聚酯的固有黏 度降低，亦能夠得到同樣的效果。較佳的固有黏度係如前 述。 而且，藉由調整後述雙軸拉伸的條件，亦能夠某種程 度控制面配向係數。爲了降低面配向係數，可將縱向拉伸 或橫向拉伸的拉伸溫度設定爲較高，或是將拉伸倍率設定 爲較低，或是將熱處理溫度設定爲較高。較佳的雙軸拉伸 條件係如後述。 〇 (光學特性） 接著，本發明之特徵係表面霧度爲15 %以上、且內部 霧度小於表面霧度。表面霧度係來自表面凹凸的特性。因 此，從薄膜表面射出光線時，或是光線入射薄膜表面時， 藉由在光擴散層的表面凹凸，光線產生折射而使表面霧度 變高。因此，表面霧度基本上係與總光線透射率無關係。 因此，藉由提高表面霧度，能夠在抑制總光線透射率的降 低之狀態，來提高光擴散性。 〇 另一方面，內部霧度係來自薄膜內部的光散射之特 性。因此，由於入射光往後方散射的影響，總光線透射率 降低。因此，爲了製造具有優良的光擴散性及高總光線透 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15 %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 -38- 200933202 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60%，上限値以 70%爲較佳，上限値以80%爲更佳。表面霧度爲80%以下 時，能夠抑制內部霧度，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4 0 %爲佳，以3 0 %爲較佳，以2 0 %爲更佳，以1 〇 % 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 〇 霧度變成擔任薄膜的光擴散功能之主體，在薄膜內部產生 光散射（伴隨著後方反射），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8 8 %爲更佳。 又，光擴散性薄膜的光擴散性能例如能夠藉由影像鮮明 〇度來定量性評價。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JIS K 7 105「塑 膠的光學特性試驗方法」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2 0 %爲較佳，上限値以1 5 %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 -39- 200933202 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(〇)、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 Φ 影像鮮明度降低，能夠得到良好的遮蔽性。而且，表面凹 凸結構的不均較少之表面光擴散性聚酯薄膜能夠緻密地形 成較小周期的表面凹凸結構，觀察到此種表面凹凸結構的 薄膜在N = 3度時之S(3)的値有較大的傾向。本發明的表面 光擴散性聚酯薄膜能夠得到S(l)爲75%以上且S(3)爲30% 以上的値。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。又，S(3)的値小於30% 時，因爲依照組合之透鏡薄片或稜鏡薄片、液晶面板等， φ 會產生所謂波紋或閃爍之問題，乃是不佳。 S(N) = 1(N)/I(0)xl00 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I ( 0 )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 散性聚酯薄膜，S (1 )的上限値以9 9 %爲佳，以9 5 %爲較佳， 以85%爲更佳。基於相同的理由，S(3)的上限値以50%爲 佳’以4 5 %爲較佳，以4 0 %爲更佳。 (力學特性） -40- 200933202 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150 °C之尺寸變化率於橫向、縱向的 任一者都是以3%以下爲佳，較佳的上限爲2.5%，更佳的 上限爲2%，特佳的上限爲1.5%，更特佳的上限爲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 0 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（卷 取方向），縱向係指與其垂直的方向。 又，薄膜的拉伸強度的下限以lOOMPa爲佳，以130MPa 爲更佳，以160MPa爲特佳。拉伸強度爲lOOMPa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。 φ 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，將薄膜卷繞於輥上 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100 °C加熱處理30分鐘後的卷曲値以5毫米以下爲 佳。 •41 - 200933202 卷曲値爲5毫米以下時，例如作爲光擴散性薄膜而組 入最後製品時，在無拉伸下的作業時，處理性變爲良好。 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。 關於卷曲的抑制，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、卷取等各製程所 賦予薄膜表背的結構差異所產生之卷曲，以應用積極地使 其產生薄膜表背的結構差異，並與，必然性的結構差異互相 補足來使卷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且採用兼顧薄膜表背的結構或 物性之條件，來實現零卷曲的製膜。 φ 又，爲了作爲在跨及全寬度範圍爲低卷曲狀態且能夠 穩定地生產之基本條件，使用厚度不均較少的拉伸處方亦 是重要的。 更具體地，對於剛製膜後在縱向卷曲，係控制縱向拉 伸時之薄膜背表的的結構差異，且橫向卷曲係藉由控制橫 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，來抑制卷曲爲佳。 又，本發明的表面光擴散性聚酯薄膜的厚度係任意， -42- 200933202 沒有特別限制，以在2 5 ~ 5 0 0微米的範爲佳’以在7 5〜3 5 0 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 ® 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。止塵埃混入空氣，以使用ΗΕΡΑ過濾器 並使用潔淨化過的空氣爲佳。此時所使用的ΗΕΡΑ過濾器， 係以使用公稱過濾精度爲具有截留9 5 %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lOOppm。接著，計量、混合各原料並供給至擠壓 機，並進行熔融擠壓成爲薄片狀。而且，使用靜電施加法 來使熔融狀態的薄片黏附於已控制表面溫度爲10〜50 °C之 金屬製的旋轉滾筒（冷硬滾筒），並且從相反面噴吹冷風來 而冷卻固化，來得到未拉伸PET薄片。在本發明，各原料 之中’關於非相溶添加劑，使用將基材聚合物的全部或一 部分與非相溶性添加劑預先使用擠壓機熔融混合而成之預 混煉母顆粒係重要的。 此時’藉由將從擠壓機的熔融部、混煉部、聚合物管、 -43- 200933202 齒輪泵、過濾器爲止的樹脂溫度控制爲220~290°C，並將 隨後的聚合物管、模頭爲止的樹脂溫度控制爲210〜29 5 °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 t之任何 場所進行高精度過濾，用以除去樹脂中所含有的異物。熔 融樹脂的高精度過濾所使用的濾材，因爲除去樹脂中以 Si、Ti、Sb、Ge、Cu作爲主成分之凝聚物或高熔點的有機 物之性能優良，以不鏽鋼燒結體爲佳。進行高精度過濾時， ❹ 熔融樹脂的溫度若低於275 °C時，由於濾壓上升而進行使 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9 5%)爲 20微米以下，以15微米以下爲佳。濾材的過濾粒子尺寸（初 期過濾效率爲95%)大於20微米以上時，難以充分地除去 大於20微米以上之大的異物。藉由使用過濾粒子尺寸（初 期過濾效率爲95%)爲20微米以下的濾材來進行熔融樹脂 的高精度過濾，雖然會有生產性降低的情形，但是爲了得 〇 到粗大粒子所引起光學缺點少的薄膜係重要的製程。又， 在本發明，藉由使用與結晶性共聚酯爲非相溶性的熱塑性 樹脂作爲添加劑，上述的高精度過濾變爲可能。 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。 -44- 200933202 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〇·〇〇5~〇·20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 Ο 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 Φ 刀法 '浸漬塗布法及簾流塗布法等，此等方法可單獨或組 合塗布。 從在稜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、或是丙烯酸 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100 質量％構成該樹脂層之樹脂，前述樹脂的至少i種係含有 -45- 200933202 5 0質量％以上。 又’爲了提高薄膜的透明性，若在支撐層（Α)中未含有 粒子、或是只有含有未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’該等粒子使用可見光線的波長以下之平 均粒徑非常小的粒子係重要的。 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 〇 準的粒子平均最大直徑）爲0.005-1.0微米。就確保薄膜的 透明性、處理性及耐擦傷性而言，粒子的平均粒徑的上限 以0.5微米爲更佳，以0.2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0.01微米爲更佳， 以〇.〇3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300〜5 00個粒子的 -46- 200933202 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 (TEM)，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拍攝300〜500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 ® 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。 © 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 -47- 200933202 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爲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 K 7367-5，溶劑係使用苯酚（60質量％)與 1，1，2,2-四氯乙烷（4〇質量。/。）的混合瘠劑，在3〇°C測定。 (2) 結晶熔解熱量、熔點及玻璃轉移溫度 使用SIINanoTechnology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300 °C加 熱熔融5分鐘後，使用液態氮急速冷卻，並以20°C /分鐘的 速度將10毫克已粉碎的樹脂試樣升溫，並進行差示熱量分 〇 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（Tem)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 121-1987、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】IS K 7199「使用塑膠毛細管 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 -48- 200933202 CAVIROGRAPH 1B、並使用φΐ毫米、L/D = 10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608.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 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 卷取橫向爲3公尺、縱向爲5公分的長度之連續的帶 ❹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（％) = ((dmax)-(dmin)/d)xl00 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JIS K 7105「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 -49- 200933202 將在薄膜試片的兩面以2片塗布柏木油（塗布量：每面 20±10克/平方公尺）、霧度爲小於1〇%的高透明聚對酞酸 乙二酯薄膜（例如’東洋紡績公司製、A4300、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 片該高透明聚對酞酸乙二酯薄膜隔著柏木油疊合而成者作 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 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 ❹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（12 V、50 W)，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 -50- 200933202 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0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0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 〇 的指標。在本發明係使用s( 1 )，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，又，使用S(3) 作爲被認定與組入液晶顯示器時發生的波紋或閃爍相關的 値。 S(N) = I(N)/I(0)x 1 00 (9)配光不均 光擴散薄膜的配光不均係藉由以下的方法來評價。將 光擴散薄膜使光擴散層朝上而放置在玻璃載片上並重疊玻 〇 璃蓋片而固定。使用光學顯微鏡（對物5倍、對眼1〇倍）並 以透射光源進行觀察，從光擴散薄膜的上面調整焦點並調 整焦點於凸部時，將明暗的分布狀態均勻者評價爲〇，不 均勻者爲X。 (1 0)拉伸強度 依據JIS C 2 3 1 8- 1 997 5 .3.3 (拉伸強度及延伸率）來測 定。 (11)尺寸變化率 依據JIS C 2318-1 997 5·3·4(尺寸變化率）來測定。 -51- 200933202 (12) 面配向係數（△ P) 依據118〖714 2- 1 99 6.5.1 (八法）’使用鈉〇線作光源 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 (13) 卷曲値 將薄膜單片狀地切取縱向100毫米、橫向50毫米，並 © 在無負荷的狀態於1〇〇 °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，並將該平均値作爲卷曲値，且 依照下述的基準來評價。 〇：卷曲値爲5毫米以下 X:卷曲値爲5毫米以上 〇 實施例1 (1)結晶性同元聚酯樹脂（Μ 1 )的製造 將酯化反應罐升溫，在到達200°C的時點，加入由86.4 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0.017質量份三氧化銻及0.16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， 進行加壓酯化反應。隨後，使酯化反應罐內恢復常壓，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260°C，添加0.012質量 -52- 200933202 份磷酸三甲酯、接著添加0.0036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260 °C升溫至280°C，且在285°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 〇 結晶性同元聚酯樹脂（Ml)之結晶熔解熱爲35mJ/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58ppm、P含量爲々Oppm.、，顏 色L値爲56.2、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100莫耳％酞酸單位作爲芳香族二羧酸成分、以70 莫耳％乙二醇及30莫耳％新戊二醇作二醇成分，依據（Ml) © 的製造方法來製造固有黏度爲0.59dl/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147Pa· s的聚苯乙烯樹脂（PS)。 (4) 非相溶性添加劑預混煉母顆粒（Μ B 1 )的調製 將70.0重量％在135t減壓乾燥6小時（1托）後之結晶 性同元聚酯樹脂（Ml)及30.0重量％聚苯乙烯（M3)進行顆粒 混合而成者，供給至已調溫至285。(：之雙軸擠壓機，並以 每分鐘50轉、吐出量爲每小時約7·5公斤、擠壓機內滯留 -53- 200933202 時間爲約6分鐘進行混煉並擠出，且將所得到的股線冷 卻、切斷來調製非相溶性添加劑預混煉母顆粒（MB1)。 (5)塗布液（M4)的調製 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 及〇.1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240°C以1小時進行酯化反應後，在250°C減壓下（1〇〜0.2 ® 毫米Hg)，以2小時進行縮聚反應，來得到數量平均分子 量爲19,500的共聚合聚酯系樹脂。 將7.5質量份所得到的共聚合聚醋，系樹脂的3 0質量％ 水分散液、11.3質量份以亞硫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、39.8質量份水及37.4質量 份異丙醇各自混合。 而且，添加0.6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、〇.5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1〇微米的數型聚丙稀製過濾器進行精密 過濾，來調整塗布液（M4)。 (6)表面光擴散性聚酯薄膜的製造 將光擴散層（B)的原料之33.4質量％在135°C減壓乾燥 -54 - 200933202 (1托）6小時後之結晶性同元聚酯（Ml)、33.3質量％在70°C 減壓乾燥（1托）12小時後之共聚合聚酯（M2)及33.3質量％ 在135 °C減壓乾燥（1托）6小時後之聚苯乙烯預混煉母顆粒 (MB 1)混合，並供給至擠壓機2。又，將支撐層（A)的原料 之在135 °C減壓乾燥（1托）6小時後之結晶性同元聚酯（Ml) 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27 5 °C，使過濾器後的聚合物管 © 的設定溫度爲270°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80對20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95% 10 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30 〇 °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’冷卻轉筒牽引未拉伸 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77°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100 °C的方式控制加熱器溫度。 縱向拉伸結束後’將所得到的單軸拉伸薄膜冷卻至5 0 °C後，在薄膜的兩面塗布塗布液（M4) °塗布液塗布量兩面 -55- 200933202 各爲約15克/平方公尺的方式控制。隨後，使用乾燥爐乾 燥塗布面。 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120 °C後，於135°C在寬度方向拉伸 2.5倍後，於140 °C在寬度方向拉伸1.6倍，進而於240 °C 熱處理10秒，並在冷卻至60°C的過程在寬度方向進行3.3% 的鬆弛處理，來製成總厚度爲1〇〇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)層的吐出來採取（A)層單獨的未拉伸薄膜。同樣地， 暫時停止（A)層的吐出來採取（B)層單獨的未拉伸薄膜。 ·> (7)薄膜特性 本實施例1所得到的薄膜特性係如表1所示。又，在 本實施例1所得到的薄膜的配光不均的觀察影像係如第1 圖所示。由表1可得知在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， 從總霧度的大部分係藉由表面霧度來賦予，且影像鮮明度 小、s(l)大，得知隱蔽性優良。而且，從第1圖能夠知道 無配光不均，且由s(3)大，得知能夠抑制產生波紋或閃爍。 實施例2 除了作爲將光擴散層（B)的原料之30.2質量％在135°C 減壓乾燥6小時（1托）後之結晶性同元聚酯（Ml)、19.8質量 %在7 0 °C減壓乾燥12小時（1托）後之共聚合聚酯（M2)及50 質量％在1 3 5 °C減壓乾燥（1托）6小時後之聚苯乙烯預混煉 母顆粒（MB1)混合，並供給至擠壓機2，且將支撐層（A)的 -56- 200933202 原料之76.7質量份在135°C減壓乾燥（1托）6小時後之結晶 性同元聚酯（Ml)及23.3質量％在70 °C減壓乾燥12小時（1 托）後之共聚合聚酯（M2)混合並供給至擠壓機1，而且將（A) 層和（B)層的厚度比率控制爲90對1〇，並且使流動方向的 拉伸時藉由預熱輥加熱的溫度爲79 °C，且將塗布液（M4)只 有塗布在支撐層（A)側的表面一側以外，使用實施例1所示 同樣的方法來製造實施例2的表面光擴散性聚酯薄膜。 本實施例2所得到薄膜特性係如表1所示。從表1得 〇 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 除了將作爲光擴散層（B)的原料之42.5質量％在13 5°C 減壓乾燥6小時（1托）後之結晶性同元聚酯（Ml)、20.8質量 %在7(TC減壓乾燥12小時（1托）後之共聚合聚酯（M2)及 36.7質量％在135t減壓乾燥（1托）6小時後之聚苯乙烯預 混煉母顆粒（MB 1)混合，並供給至擠壓機2，且以拉伸後的 薄膜厚度爲188微米的方式藉由冷卻轉筒調整未拉伸薄膜 Q 的牽引速度，並且將支撐層（A)的原料之76.7質量份在135 °(：減壓乾燥（1托）6小時後之結晶性同元聚酯（Ml)及23.3 質量份在70 °C減壓乾燥12小時（1托）後之共聚合聚酯（M2) 混合並供給至擠壓機卜而且將（A)層和（B)層的厚度比率控 制爲8 9對1 1，並且在流動方向拉伸3.3倍且以1 3 5 °C在寬 度方向拉伸2.4倍後，以140°C在寬度方向拉伸1.6倍，進 而以240 °C熱處理17秒，且在冷卻至60 °C之過程在寬度方 向進行1 · 3 %的鬆弛處理以外，使用實施例1所示同樣的方 法來製造厚度爲188微米之實施例3的表面光擴散性聚酯 -57- 200933202 薄膜。 本實施例3所得到薄膜特性係如表丨所示。從表1得 知本實施例3與實施例1同樣地具有優良的特性。 實施例4 除了寬度方向的拉伸後，以235 °C進行熱處理17秒， 且在冷卻至60 °C之過程在寬度方向進行〇_8 %的鬆弛處理 以外，使用實施例3所不同樣的方法來製造實施例4的表 面光擴散性聚酯薄膜。 ® 本實施例4所得到薄膜特性係如表1所示。從表丨得 知本實施例4與實施例1同樣地具有優良的特性。 實施例5 除了寬度方向的拉伸後，以235 °C進行熱處理17秒， 且在冷卻至60 °C之過程在寬度方向進行3.3 %的鬆驰處理 以外，使用實施例3所示同樣的方法來製造實施例4的表 面光擴散性聚酯薄膜。 本實施例5所得到薄膜特性係如表1所示。從表1得 © 知本實施例5與實施例1同樣地具有優良的特性。 比較例1 除了作爲將光擴散層（B)的原料之60質量份在135°C 減壓乾燥6小時（1托）後之結晶性同元聚酯（Ml)、30質量 份在70 °C減壓乾燥12小時（1托）後之共聚合聚酯（M2)及10 質量份聚苯乙烯（M3)混合，並供給至擠壓機2，並且將100 質量份支撐層（A)的原料之在135°C減壓乾燥（1托）6小時後 之結晶性同元聚酯（Ml)供給至擠壓機1以外，使用實施例 1所示同樣的方法來製造比較例1的表面光擴散性聚酯薄 -58- 200933202 膜。 本比較例1所得到薄膜特性係如表1所示。又，本比 較例1所得到的薄膜的配光不均之觀察圖係如第2圖所 示。如從第2圖所得知，因爲本比較例1的薄膜能夠觀察 到接近全高畫質（full HD)的液晶面板之間距（大約400微米） 大小之配光不均，所以容易產生所謂波紋或閃爍之顯示品 質低落。 比較例2 ® 除了將作爲光擴散層（B)的原料之65.2質量份在135 °C減壓乾燥6小時（1托）後之結晶性同元聚酯（Μ 1)、1 9.8 質量份在70 °C減壓乾燥12小時（1托）後之共聚合聚酯（M>2) 及15質量份聚苯乙烯（M3)混合，並供給至擠壓機2以外， 使用實施例2所示同樣的方法來製造表面光擴散性聚酯薄 膜。 本比較例2所得到薄膜特性係如表1所示。 比較例3 ❹ <共聚合聚酯樹脂（M5)的製造> 將芳香族二羧酸成分之100莫耳％對酞酸單位、二醇 成分之70莫耳％乙二醇單位及30莫耳％環己烷二甲醇單位 作爲構成成分，來製造固有黏度爲O.60dl/g、熔融黏度爲 197Pa*s的結晶性共聚合聚酯樹脂（M5)。 除了將作爲光擴散層（B)的原料之40質量份在135 °C 減壓乾燥6小時（1托）後之結晶性同元聚酯（mi)、40質量 份在70 °C減壓乾燥12小時（1托）後之共聚合聚酯（M5)及20 質量份聚苯乙烯（M3)混合，並供給至擠壓機2，且將支撐 -59- 200933202 層（A)的原料之50質量份在135 °C減壓乾燥（1托）6小時後 之結晶性同元聚酯（Ml)及50質量％在70 °C減壓乾燥12小 時（1托）後之共聚合聚酯（M2)混合並供給至擠壓機1,而且 橫向拉伸後以2 3 5 °C熱處理以外，使用比較例2所示同樣 的方法來製造比較例3的表面光擴散性聚酯薄膜。 本比較例3所得到薄膜特性係如表1所示。 比較例4 除了將塗布液（M4)塗布在薄膜的兩面以外，使用比較 ❹例2所示相同的方法來製造比較例4的表面光擴散性聚酯 薄膜。 本比較例4所得到的薄膜之特性係如表1所示。 比較例5 除了以拉伸後的薄膜厚度爲250微米的方式藉由冷卻 轉筒調整未拉伸薄膜的牽引速度，將（A)層和（B)層的厚度 比率控制爲96對4，使流動方向的拉伸時藉由預熱輥加熱 的溫度爲79°C，並且在流動方向拉伸3.3倍且以135°C在 〇 寬度方向拉伸2.4倍後，以140 °C在寬度方向拉伸1.6倍， 進而以240°C熱處理22秒，且在冷卻至6(TC之過程在寬度 方向進行1.3 %的鬆弛處理以外，使用比較例1所示同樣的 方法來製造厚度爲250微米之比較例5的表面光擴散性聚 酯薄膜。 本比較例5所得到的薄膜之特性係如表1所示。 比較例6 除了將作爲光擴散層（B)的原料之69質量份在135°C 減壓乾燥6小時（1托）後之結晶性同元聚酯（Μ 1 )、2 1質量 -60- 200933202 份在70 °C減壓乾燥12小時（1托）後之共聚合聚酯（M2)及10 質量份聚苯乙烯（M3)混合，並供給至擠壓機2，且將（A)層 和（B)層的厚度比率控制爲90對10以外，使用比較例5所 示同樣的方法來製造比較例6的表面光擴散性聚酯薄膜。 本比較例6所得到薄膜特性係如表1所示。 比較例7 除了將作爲光擴散層（B)的原料之62質量份在135°C 減壓乾燥6小時（1托）後之結晶性同元聚酯（Ml)、31質量 © 份在7〇°C減壓乾燥12小時（1托）後之共聚合聚酯（M2)及7 質量份聚苯乙烯（M3)混合，並供給至擠壓機2，且將塗布 液（M4)只有塗布在支撐層（B)側的表面一側以外，使用實施 例5所示同樣的方法來製造比較例7的表面光擴散性聚酯 薄膜。 本比較例7所得到薄膜特性係如表1所示。 比較例8 除了將作爲光擴散層（B)的原料之58.9質量份在135 ❹ °C減壓乾燥6小時（1托）後之結晶性同元聚酯（Ml)、34.1 質量份在70 °C減壓乾燥12小時（1托）後之共聚合聚酯（M2) 及7質量份聚苯乙烯（M3)混合，並供給至擠壓機2,且將（A) 層和（B)層的厚度比率控制爲84對16以外，使用實施例3 所示同樣的方法來製造比較例8的表面光擴散性聚酯薄 膜。 本比較例8所得到薄膜特性係如表1所示。 比較例9BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffusing polyester film such as a backlight panel module or a lighting device used for a large-screen and high-brightness liquid crystal display. More specifically, there is a surface light diffusing polyester film which is small in curl due to light diffusibility and light transmittance and which is accompanied by temperature change. [Prior Art] In recent years, the technical progress of liquid crystal displays has been remarkable, and it has been widely used as a display device for personal computers or televisions, mobile phones, and the like. In particular, in recent years, various applications of liquid crystal displays, high-definition progress, especially in television applications, along with the popularization of high-visual broadcasts, the horizontal 1 centered on the adoption of large-screen liquid crystal displays. The 920X vertical 1 0 8 0, which is a full HD display, is gradually being used in liquid crystal displays with smaller picture sizes, and the requirements for high definition are getting higher and higher. Since the liquid crystal display unit alone does not have a light-emitting function when it is used alone, it is necessary to provide a backlight module ® on the back side thereof for display. 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 in large-sized liquid crystal displays such as large liquid crystal TVs that require high brightness. Another method is an edge light type method in which a light source is disposed outside the illuminating surface, and is attached to one or both sides of a light guide plate made of a transparent acrylic 200933202 resin plate or the like disposed on the illuminating surface. A lamp (mostly a cold cathode discharge tube) or the like is formed by a substantially linear illuminator 'and a light cover made of a reflector to introduce light into the light guide plate. This method has the characteristics of low power consumption, small size, and thinness. Therefore, it is widely used for small-sized displays such as notebook personal computers, and the like, which is required to be thinner and lighter. 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 total reflection 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 扩散 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 tantalum film or a lens film 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 plurality of prismatic shapes, minute irregularities such as a wavelength and a pyramid shape are arranged, and the emitted light of the diffuse diffusing film is collected on the front surface to increase the brightness of the illuminating surface. Such a ruthenium film is used by disposing one sheet or two sheets on the surface side of the diffusing film. Further, in order to make the unevenness of the luminance caused by the arrangement of the above-mentioned enamel sheet or the defect of the sheet of 200933202, the film has a light diffusing film disposed on the surface side of the enamel sheet. The light-diffusing film used in the above-described backlight module is obtained by applying a light-diffusing layer made of a transparent resin containing fine particles to the surface of the biaxially stretched polyester film (for example, see Patent Document 1). 2) For the mainstream. Patent Document 1: Japanese Laid-Open Patent Publication No. Hei No. No. No. No. 3698978. However, since it is necessary to provide a light diffusion layer on one side of the base film by the method, there is a possibility. The linear diffusion coefficient of the light-diffusing layer and the base film is different. The light-diffusing film has a bimetallic structure or a problem that curling is likely to occur due to heating. This problem has become an important problem in particular, in recent years, large-sized liquid crystal TVs and the like, which employ a large-sized liquid crystal display of a direct-type backlight module which has a high brightness. The larger the area of the light diffusing film is, the more the curl becomes more remarkable. Moreover, the higher the brightness of the liquid crystal display, the greater the power consumption of the light source, that is, the heat generated by the backlight module. In order to solve this problem, it is necessary to eliminate the bimetallic shape. A hard coat layer (non-light-diffusing layer) having a thickness of several micrometers to several tens of micrometers is usually formed on the surface of the light-diffusing layer of the base material film, and a countermeasure of balancing the linear expansion stress by sandwiching both surfaces of the light-diffusing layer is employed. However, the thickness of the hard coat layer is not originally required, and when the light diffusing film is increased to an unnecessary thickness, it may cause an increase in manufacturing cost. Further, there is a limit to countermeasures for balancing the linear expansion stress of the front and back, and only a sufficient effect can be obtained in the large-screen, high-brightness display as described above. Further, in recent years, in order to reduce the number of backlight module assemblies, or to simplify and reduce the cost of the 200933202 process, many proposals have been made to integrate the light diffusing film with other optical functional films. For example, there is disclosed a ruthenium sheet (refer to Patent Document 3), which is characterized in that a first row side of a plate-shaped light-transmitting substrate having two main surfaces of a first surface and a second 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) is disclosed, which is 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 mixed light. The thermoplastic resin layer formed of a diffusing agent is formed by forming a prism shape on the surface of the thermoplastic resin layer in which the light diffusing agent is not kneaded. Further, a light-scattering biaxially stretched polyester film for prism sheets (see Patent Document 5) is disclosed, which imparts light diffusibility by a light scattering agent added inside the film and voids generated around the film. . Patent Document 3: Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. The light-transmitting particles 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 a 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. In addition, in recent years, many biaxially stretched polyester films which have excellent heat resistance, mechanical strength, and thickness uniformity have been imparted with light diffusing properties. The polyester film composed of a single material in nature has light diffusibility, can solve the problem of the above-mentioned heating curl, or can open a way to integrate the functions of the diffusion sheet and the tantalum film, and the industrial price is very large. of. However, it has been proposed in the past to test the biaxially stretched polyester film itself for light diffusibility, and either of them may impair a certain characteristic (heat resistance, mechanical strength, etc.) of the biaxially stretched polyester film itself. It is also a property of a light diffusing film that impairs light transmittance or so-called light diffusibility, and cannot be put into practical use. 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 an extra strength, but since the light diffusibility is by the layer The air bubbles present inside provide 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 in a backlight module, most of the light emitted from the illuminating surface is scattered rearward, so that the light transmittance is impaired. In fact, the highest total light transmittance as shown in the examples is only 85. 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). In the above method, since the voids are eliminated, the light transmittance can be improved. However, even in this method, the light diffusibility is the same by 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 case of 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 2 A polyester having a temperature of 10 ° C or less or amorphous 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. 〇 〇 200 200 200 200 200 2002 2002 2002 2002 2002 2002 2002 2002 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 -18 Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. The resulting curl can be improved to some extent. However, there is no change in the 'crystallinity' between the interstitial intermediate layer and the surface layer in the optical expansion - 200933202. The variation in the thickness of several layers or the physical property change of the surface of the surface has a flatness in the presence of temperature changes. Significantly worse. Further, since most of the film is composed of a polyester which is remarkably lacking in 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 (see Patent Document 14) is disclosed, and spherical or lenticular particles having a specific particle diameter are prepared and formed. Patent Document 14: JP-A-2002-37898 In Patent Document 14, a film is shown in the examples, using polyethylene terephthalate as a raw material of polyester, and having a total light transmittance of 8 8% and 6 8% 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 Φ. The possibility of mechanical strength and high thickness accuracy. This is because the films are stretched by stretching the unstretched film having a thickness of 200 μm in both the longitudinal and transverse directions. 0 times, that is, the area magnification is 9. The film obtained by stretching 0 times has a thickness of 50 μm, and the actual area stretching ratio calculated by the thickness ratio before and after stretching is only 4. 〇 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. Moreover, 'the actual area stretching ratio is about 4 times of stretching, and even if it is possible to obtain -11 - 200933202 to excellent light transmittance, it is impossible to achieve the heat resistance, mechanical strength and high characteristics of the biaxially stretched film. Thickness accuracy. As described above, the problem of the curling tends to gradually become apparent as the size of the backlight module for a liquid crystal display increases with the increase in the output of the backlight module for a liquid crystal display. In order to solve the above problem, the offline problem is not used. It is preferable to use the actual stretched film itself by the coating method (Patent Documents 1 and 2). However, the biaxially stretched film itself has a light diffusing property, and it is possible to avoid voids caused by the light diffusing particles and to have a low total light transmittance (Patent Documents 3, 4, and 5). The method of avoiding the occurrence of voids, the problem of curling in the resin properties or stretching conditions previously used cannot be solved (Patent Document 6), or the problem of low mechanical strength (Patent Documents 7-14). That is, since the mechanical properties and optical characteristics of the biaxially stretched film are in contradiction, it is impossible to obtain a film which can satisfy any of the characteristics. Therefore, the above method has not been put into practical use in the conventional method in which the overall quality is not improved by the post-processing of the transparent base film. In view of the above-mentioned problems, the inventors of the present invention have previously made a prior application (1) (Japanese Patent Application No. 2007-1 907 907), the object of which is to provide a surface light diffusing polyester film having a biaxial alignment polyester. The film has excellent heat resistance, mechanical strength, thickness accuracy, and the like, and can achieve both total light transmittance and light diffusibility, and can suppress generation of heat curl from the bimetallic structure. The prior invention (I) provides a surface light diffusing polyester film capable of suppressing curl due to heating, and having excellent mechanical properties of a biaxially oriented polyester film, and capable of achieving both total light transmittance and light diffusion. Sex. In order to achieve the above characteristics, the inventors of the present invention particularly focused on the relationship between the surface alignment coefficient, the internal haze, and the surface haze of the film, and focused on it. As a result, the inventors of the present invention have found that the prior invention (I) can be completed by adopting the means described in [1] to [7] described later. DISCLOSURE OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION The support layer and the light diffusion layer of the surface light diffusing polyester film of the prior invention (I) are all composed of a crystalline polyester as a main raw material. The structure is constructed to suppress the heating curl generated by the bimetallic structure, and has excellent heat resistance, mechanical strength and thickness accuracy inherent to the biaxially oriented polyester film. In addition, since the surface light diffusing polyester film of the invention of the invention (I) is a main raw material of a light diffusion layer containing a crystalline polyester having a copolymerization component, and the surface alignment coefficient of the entire film is controlled within a specific range, Around the incompatible additive added to the light-diffusing layer, voids are not substantially generated and have a textured structure on the surface of the light-diffusing layer. Therefore, it is excellent in both surface light diffusibility and high light transmittance. In view of various utilization forms of the surface light diffusing polyester film of the invention (I), it is clear that a high-definition liquid crystal display having a high definition and high brightness has been developed, in particular, with light. The shape or spacing of the lens sheets or enamel sheets of the diffusing film combination and various other aspects of the effort. Also, the pixel pitch becomes very small in a high-definition liquid crystal display. SUMMARY OF THE INVENTION An object of the present invention is to provide a surface light diffusing polyester film which is capable of utilizing the excellent characteristics of the surface light diffusing polyester film of the prior invention (I) in a wide range of utilization forms, particularly with various types of each-13-200933202 A combination of a lens sheet or a tantalum sheet and a liquid crystal panel exhibits excellent display characteristics. Means for Solving the Problem 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) 6). © (1) having a support layer and a light diffusion layer, the support layer being composed of a crystalline polyester containing a crystalline homopolyester or a copolymerization component; and the light diffusion layer is on at least one side of the support layer It is formed by a co-extrusion method and is composed of 50 to 99 parts by mass of a crystalline polyester having a copolymerization component having a melting point of 235 to 2 55 ° C and a non-compatible one to 50 with the polyester. The composition of the mass of the additive is composed of a compound. (2) The surface alignment coefficient AP of the film defined by the following formula is 0. 08~0. 16, Δ P = (nx + ny) / 2 - nz φ Here, nx, ny, and nz each represent 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 direction and the transverse direction, and the tensile strength is more than 100 MPa in the longitudinal direction and the transverse direction. (6) The light diffusibility S(3) of the film defined by the following formula is 30% or more and less than 50%, S(3) = I(3)/I(0)x 100 -14 - 200933202 Here, 1(3) and 1(0) each represent 値 and 0 degree 扩散 of the transmitted light intensity, the diffusion angle is 3 degrees. 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 coating layer has a coating layer on the surface of the light diffusion layer, and the coating layer is formed before the stretching and alignment of the film is completed. Further, at least one or more of a 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 of at least one of an acid ester resin or an acrylic resin as a main component. The composition of the invention of claim 5, such as the surface light diffusing polyester film system of claim 1 The sheet is a coating layer containing at least one of a copolymerized polyester resin, a polyurethane resin, or an acrylic resin as a main component, on the opposite side of the light G diffusion layer. EFFECT OF THE INVENTION The surface light diffusing polyester film of the present invention has been able to suppress the curl due to heating in addition to the prior invention (I), and has excellent mechanical properties of the biaxially oriented polyester film, and can solve both of them. In addition to the spearhead problem of light transmittance and light diffusibility, the improved surface relief structure is also used when used in combination with a wide variety of lens sheets or 稜鏡-15-200933202 sheets and liquid crystal panels. It is possible to achieve an effect of preventing the display quality of the so-called ripple or flicker from being lowered. [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 also having a total light transmittance and light. When it is used in combination with a wide variety of lens sheets, enamel sheets, and liquid crystal panels, it also has the effect of preventing the occurrence of ripples or color flickering, which is called flickering, and the quality is lowered. In order to achieve the above-mentioned characteristics, the inventors of the present invention have paid particular attention to the relationship between the surface alignment coefficient of the film and the internal haze and the surface haze, and have focused on the surface uneven structure of the light diffusion layer. As a result, it has been found that such characteristics can be achieved by the means described in the following (1) to (8), and the present invention has been completed. Therefore, the characteristics of these means of achievement are first described. In addition, in order to combine the above-mentioned contradictory characteristics, it is considered that only the specific ones of the following means (1) to (8) cannot be effectively contributed, and it is necessary to use the means of (1) to (8) in combination. Implement the above features. 〇(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) Light diffusion layer constitutes inherent viscosity of resin 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 (8) Control of the surface uneven structure of the light diffusion layer (1) Light diffusion layer Control of the melting point of the resin of (B)-16-200933202 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, and A light-diffusing layer (B) comprising a blended composition of a crystalline polyester containing a copolymer component and the incompatible additive. Here, the crystalline polyester/crystalline homopolyester refers to a polyester/homopolymer 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 crystalline heat-melting heat peak as a melting point, and contains a crystalline polyester/crystalline homopolyester. 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 voids (voids) are likely to occur in the case of non-coherent particles in the resin, 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 325 ° 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 t. 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). -17- 200933202 (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. The predetermined heat resistance, mechanical strength, and thickness accuracy of the film are preferably higher than the melting point of the crystalline polyester/crystalline homopolyester constituting the support layer (A). 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 homopolymer and the crystalline polyester constituting the light-diffusing layer (B) is preferably within 25 t, and is within 20 ° C. Preferably, it is preferably 1 〇 ° C or less, and preferably 5 ° C or less. When the difference in melting point is within 25 °C, the curl generated by the bimetallic structure can be suppressed to be 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 achieve 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 introduction of the copolymerization component is preferably 3 mol% or more, more preferably 5 mol% or more, and most preferably 8 mol% or more, based on the entire aromatic dicarbon component or the entire glycol component. . When the content of the copolymerization component is more than 3 mol% or more, -18 to 200933202 is preferable because it is possible to suppress generation of voids and to easily achieve both high light transmittance and light diffusibility. On the other hand, the upper limit of the amount of introduction of the copolymerization component is preferably 20 mol% or less, more preferably 18 mol% or less, and even more preferably 15 mol% or less. When the copolymerization synthesis is classified into 2 mol% or less, the curl generated by the bimetallic structure can be suppressed to be within the practical range, which is preferable. Further, 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) (by containing the aforementioned crystalline homo-polyester, or copolymerization) The light-diffusing layer (B) is laminated on at least one surface of the crystalline polyester (the composition of the 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 of light caused by internal structures such as voids has backscattering, and high total light transmittance cannot be obtained. On the other hand, the scattering of light caused 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 imparts light diffusibility by using the above-described multilayer structure and the uneven structure 19-200933202 on the surface of the light diffusion layer (B) which is caused by the incompatible additive. It is possible to suppress light scattering (internal haze) inside the film to achieve high total light transmittance. 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, it may be a multilayer structure of three or more layers 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 ruthenium sheet. Further, the composition of the incompatible additive which can be used in the present invention is as follows. (4) Control of Thickness 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 is obtained in order to obtain the surface light-diffusing polyester film of the present invention. The thickness of the diffusion 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 or more, and particularly preferably 5 μm or more. 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. -20- 200933202 Therefore, when the thickness of the light-diffusing layer (B) is made thick, 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, 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 raised, 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 of φ, preferably in the range of 2 to 50%. The lower limit of the ratio of the light diffusion layer (B) to the total thickness 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 intended for optical use, the optical disadvantage caused by foreign matter is less preferred, and it is useful to provide a resin in the melt line by co-extruding the -21 - 33,033,202 method. A filter for removing foreign matter is preferred. 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 copolymer component constituting the light-diffusing layer (B) is preferably high. 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 be effectively dispersed to a degree which imparts a good uneven structure, resulting in a decrease in surface haze. Therefore, in order to achieve the mechanical strength and good optical characteristics of the light-diffusing layer (B), the intrinsic viscosity of the crystalline polyester containing the copolymer component constituting the light-diffusing layer resin layer is controlled to a predetermined range. good. The lower limit of the intrinsic viscosity of the crystalline polyester is 0. 5 0 dl / g is better, with 0. 52dl/g is better. Intrinsic viscosity is less than 0. 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. Moreover, the upper limit of the intrinsic viscosity of the crystalline polyester is 〇. 61dI/g is better, with 0. 59 dl / g is better. Intrinsic viscosity greater than 0. At 6 ldl/g, the dispersion diameter of the above-mentioned additive in the polyester becomes small, and the light diffusion -22-200933202 tends to decrease. (6) Control of Melt Viscosity Difference Between Substrate Polymer and Incompatible Resin The present inventors have found that the difference in melt viscosity between 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 the copolymerization component constituting the light-diffusing layer (B) and the non-compatible additive can be stirred and mixed in an extruder. 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 and the additive can be finely granulated. When the dispersion diameter of the additive is reduced, a good uneven structure cannot be obtained on the surface of the light diffusion 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 constituting the light-diffusing layer (B) and the non-compatible additive is preferably large. The melt viscosity difference is 35Pa. Preferably, the above is better than 40 Pa · s. When the difference in melt viscosity is 35 Pa·s or more, the additive has a good dispersion diameter in the poly-φ ester, 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 the surface unevenness can be formed more easily by the incompatible additive, it is preferable to use high temperature stretching in order to achieve both the total light transmittance and the light diffusibility. Further, when heat treatment is performed at a high temperature, the internal haze can be lowered because the voids disappear, and the thermal dimensional change rate of -23-200933202 is also lowered, and curling is less likely to occur during 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 achieve 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 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 120 ° C to 16 (the temperature range of TC. Further, the heat treatment is performed in the wind. It is preferable to carry out heat treatment in the range of 5 seconds to 100 seconds in a temperature range of 25 m/min or more and a temperature range of 235 to 250 ° C. Further, at this time, if the film temperature is more than 240 ° C, In the case where the optical characteristics are lowered, it is also possible to apply a longitudinal or lateral relaxation treatment after the heat treatment or the heat treatment. (8) Control of the surface uneven structure of the light diffusion layer The light diffusing polyester of the prior invention (I) The film is achieved by the above-mentioned means 〇(1) to (7). However, in recent years, among the high-definition and high-brightness functions of liquid crystal displays, changes, improvements, and light diffusing are also popular. The specification of the lens sheet or the enamel sheet liquid crystal panel of the ester film combination requires that the light diffusing polyester film can maintain excellent display characteristics in combination with various members of the members. film Various forms of use of the lens sheet, the enamel sheet, and the liquid crystal panel are often corrugated or flickering in display performance. It is considered that the light diffusing polyester film is a cause of ripple because of the light diffusing polyester film. The emitted light has a brightness of -24-200933202 unevenness, that is, uneven distribution, and if the alignment unevenness has periodicity, the periodic spacing and the lens pattern of the lens sheet or the enamel pattern of the lamella sheet, liquid crystal The pitch of the periodic structure of the pixels of the panel is disturbed, and it is considered that the unevenness of the light-diffusing polyester film overlaps with a part of the color pixels of the color filter incorporated in the liquid crystal panel. The problem of causing a change in the brightness of the color pixel is expected. The problem of the ripple or the flicker is expected to be accompanied by high definition and high brightness of the liquid crystal display, and the lens pattern, the 稜鏡 pattern, and the pixels of the liquid crystal panel become smaller and become more conspicuous. It is considered that φ even in the surface light diffusing polyester film of the prior invention (I), in accordance with the combined lens sheet or sheet, liquid The crystal panel is also likely to be corrugated or flickered due to uneven light distribution. The uneven light distribution of the surface light diffusing polyester film is caused by the uneven structure of the surface of the light diffusion layer. I), the base polymer constituting the light-diffusing layer (B) and the incompatible additive are stirred and mixed in the extruder. In this method, the mixed base polymer and the non-phase are stirred in the extruder. In the case of a soluble additive, if sufficient mixing and mixing Q is not performed to uniformize the dispersion state and distribution state of the additive particles, or unevenness in particle size increase due to re-agglomeration of the additive particles, it may be difficult. Convergence to a uniform particle size. When the film of the light-diffusing layer (B) containing such uneven additive particles is stretched and heat-treated, uneven distribution or graininess is likely to occur due to the additive particles in the light-diffusing layer. The unevenness of the diameter and the uneven structure on the surface of the light diffusion layer are likely to be uneven. In view of the above, it is possible to prevent the unevenness of the additive particles in the light-diffusing layer (B) as described above while taking countermeasures of the above (1) to (7), and as a result, the following is achieved by the following measures. The way to solve the -25- 200933202 countermeasures. That is, all or a part of the base polymer constituting the light-diffusing layer (B) is melt-mixed with an incompatible additive in advance using an extruder to prepare pre-mixed mother particles, which are then stirred and mixed using an extruder. The mother particles (and the residual base polymer) are pre-blended and co-extruded with the substrate layer (A) to form a film. In the light-diffusing layer (B) of the film thus formed, the incompatible additive is uniformly dispersed in the base polymer in comparison with the prior invention (I) and the uniformity of the particle diameter thereof is larger than that of the prior invention. (I) Excellent. Therefore, by stretching and heat-treating the film, it is possible to form a uniform uneven structure in which the uneven structure or the so-called undulation unevenness is small on the surface of the light-diffusing layer (B). In combination with the conditional control of the above (1) to (7), the uniformity of the surface uneven structure of the light-diffusing layer (B) is reflected by the light-diffusing property of the surface light-diffusing polyester film. The light diffusing property S(3) of the surface light diffusing polyester film of the present invention represented by the following formula is 30% or more and less than 50%. When S(3) is used as a diffusing film of a liquid crystal display, the light diffusing polyester film of this range can be suppressed from being combined with a lens sheet, a ruthenium sheet, or a liquid crystal panel. problem. When S(3) is less than 30%, 〇 due to the unevenness of the surface uneven structure, corrugation or flicker may occur depending on the combination of the lens sheet, the enamel sheet, and the liquid crystal panel used, which is not preferable. When s(3) is more than 50%, the relative enthalpy of 1(0) to 1(3) is inevitably small, and as a result, the brightness of the front surface of the backlight module is low, which is not preferable. S(3)=I(3)/I(0)x100 Here, 1(3) and 1(0) each represent 値 and 0 degree 扩散 of the transmitted light intensity, the diffusion angle is ±3 degrees. 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). -26- 200933202 In order to achieve the necessary condition (2) as in the first paragraph of the patent application, 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 conditions as in the first paragraph of the patent application scope (4. It can be achieved by implementing the conditional control of the above means (3) to (7). In order to achieve the condition (5) necessary for the first item of the patent application, it can be achieved by implementing the conditional control of the above means (1) to (4) and (7). 〇 In order to achieve the necessary condition (6) as in the first paragraph of the patent application, it can be achieved by implementing the conditional control of the above means (1) to (8). According to the present invention, it is considered that the means (1) to (8) 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 curl caused by a 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 the light transmittance and the zero light diffusibility are highly balanced. 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 ° (: when borrowed in the stretching process) The stretching temperature difference is imparted to the respective faces of the support layer (A) and the light diffusion layer (B), and the stretching is performed on the surface side of the support layer (A) and the surface of the light diffusion layer (B) -27-200933202. The surface light diffusing polyester film which has been controlled to be curled by the bimetallic structure can be obtained by controlling the difference in the alignment state and controlling the difference in the linear expansion coefficients on both sides of the film. The method of controlling the surface haze generated by the surface unevenness (formed by the addition of the dispersed additive) is shown. The above description reveals the technical idea of how to control the dispersion diameter of the additive, and if it is the manufacturer, This technical idea is easily implemented by a method different from the above method. That is, even if the crystalline polyester containing the copolymer component constituting the light diffusion layer (B) is intrinsic, the inherent viscosity is larger 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 interval of the T die and controlling the shearing force at the time of 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 φ 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-styrene copolymer can be obtained by copolymerizing 1 mol of glycidyl 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 -28-200933202, the technical idea can be easily implemented by a method different from the above method. That is, even if the stretching temperature of the film is used, by using a simultaneous biaxial stretching machine, the tensile stress can be controlled to lower the stretching speed, thereby suppressing generation of voids. Further, in order to obtain the composition 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 decanoic acid, isophthalic acid or naphthalene dicarboxylic acid or an ester thereof, and ethylene glycol or diethylene glycol. A polyester produced by polycondensation of a glycol such as 1,3-propanediol, 1,4-butanediol or neopentyl glycol. These polyesters can be produced by a direct polymerization method in which an aromatic dicarboxylic acid and a glycol are subjected to a transesterification reaction, and can also be subjected to a transesterification reaction with a glycol ester of an aromatic dicarboxylic acid and a glycol. 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 propylene diacrylate, polybutylene terephthalate, and polyethylene 2,6-naphthalenedicarboxylate. 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. Polyester, its structure, minutes -29- 200933202 sub-quantity and composition can be arbitrary and not limited. 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. A copolymerized polyester composed of a diol component is preferred. The branched aliphatic glycol may, for example, be neopentyl glycol, 1,2-propanediol or 1,2-butanediol. Further, the alicyclic glycol may, for example, be 1,4-cyclohexanedimethanol or tricyclodecane dimethylol. ❹ Among them, neopentyl glycol or 1,4-cyclohexanedimethanol is particularly preferred. Further, in the present invention, in addition to the above diol component, 1,3-propanediol or 1,4-butanediol is used as the copolymerization, and the synthesis is classified into a preferred embodiment. When the diol is introduced as a copolymerization component in the above range, it is preferable to impart the above characteristics, and it is preferable to reduce the light transmittance and light diffusibility from the voids in the light diffusion layer. In terms of it, it is also better. Further, as the above-mentioned polyester, one or two or more kinds of the following dicarboxylic acid component 〇 and/or diol component may be used as a copolymerization component. Other dicarboxylic 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-4,4'. - an ester-forming derivative of an aromatic dicarboxylic acid such as a dicarboxylic acid, a diphenoxyethane dicarboxylic acid 'diphenyl milling dicarboxylic acid, a 5-sodium sulfonic acid isononanoic acid or a citric acid; or the like; (2) Ester dicarboxylic acids such as oxalic acid 'succinic acid, adipic acid, azelaic acid, dimer, maleic acid, fumaric acid, glutaric acid or the like, or ester-forming derivatives thereof (3) an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid or an ester-forming derivative thereof; and (4) a hydroxyl group such as p-hydroxybenzoic acid or hydroxycaproic acid; 30-200933202 carboxylic acid or the like An ester-forming derivative or the like. On the other hand, other diol components which can be used in combination with ethylene glycol and a branched aliphatic diol and/or an alicyclic diol include aliphatic diols such as pentanediol and hexanediol, and double An aromatic diol such as phenol A or bisphenol S or an ethylene oxide adduct thereof, diethylene glycol, triethylene glycol or a dimer diol. 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.触 For the catalyst used in the production of the above polyester, for example, an alkaline earth metal compound, a manganese compound, a cobalt compound, an aluminum compound, a ruthenium compound, a titanium compound, a titanium/ruthenium composite oxide, a ruthenium compound or the like can be used. Among these, in terms of catalyst activity, a titanium compound, a ruthenium compound, a ruthenium compound, and an aluminum compound are preferred. 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 may be used as a film raw material as it is, or a copolymerized polyester having a large copolymerization component and a homopolyester (for example, polyethylene terephthalate). Blending to adjust the copolymerization component. In particular, by using the latter method to produce a film, it is possible to have the same light diffusibility and total light transmittance as when only a copolymerized polyester is used, and to adjust a copolymerized component having a high melting point (heat resistance). Crystalline polyester. Further, it is also preferable to introduce a third component (copolymerization component) -31 - 200933202 into the main chain by melt-mixing two different kinds of crystalline polyesters and using a transesterification reaction between the two. In particular, a blend of at least one of the above-mentioned copolymerized polyester, polyethylene terephthalate, and polyethylene terephthalate (for example, polybutylene terephthalate or polypyrene) is blended. 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 free of particles" means that, for example, when inorganic particles are quantified by fluorescence X-ray analysis, it is 50 ppm or less, preferably less than 10 ppm, and the lower limit is Very good. Thus, by using a non-pure, 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 (emitted 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 in the field of surface relief forming agent-32 - 200933202. By using this technique, foreign matter is filtered by a high-precision filter in a melting and extruding process of a film, and a film for a liquid crystal display can achieve the necessary cleanliness. When the non-melting polymer particles or the inorganic particles to be described later are used as an additive, the fineness of the opening of the filter which can be used in the process of the film is limited, 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 achieve a high light diffusing total light transmittance. © A thermoplastic resin which is incompatible with 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 Φ for 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 -33-200933202 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 (manufactured by Standford Research Systems, Inc., Μ PA 100 type) can be used, from 30 ° C to 350 ° C. When the temperature is raised by 1 ° C/min, the composition is not deformed by flow deformation. 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, and a melamine resin. And organic lanthanide resins. 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 35 (TC or more, a non-crosslinked polymer may be used, but in terms of heat resistance, a polymer having a crosslinked structure is used. The crosslinked polymer particles are preferably formed. The average particle diameter of the above non-melting polymer particles is 0. 1 to 50 μm is preferred. The lower limit of the average particle diameter of the above non-melting polymer particles is 〇. 5 is better. It is especially good at 5 microns. In order to exhibit a good light diffusing effect, the non-melting polymer particles preferably have an average particle diameter of 0 μm or more. On the other hand, the upper limit of the average particle diameter of the above non-melting polymer particles is more preferably 30 μm, and particularly preferably 20 μm. When the average particle diameter of the non-melt 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 as much as possible. -34 - 200933202 The above non-melting polymer particles may be used in one type or in two or more 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. A photograph of the particles was taken using a scanning electron microscope (SEM), and the maximum diameter of 300 to 500 particles was measured with a minimum particle size of 1 to 5 mm, and the average 値 was used as the average particle. path. 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 0. 1 to 50 microns is preferred. With e 0. 5 to 30 microns is more - preferably 1 to 20 microns. The average particle size is less than 0. A good light diffusion effect cannot be obtained at 1 micrometer. Conversely, 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 defects of the film. 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 of the particles of 3 0 0 to 500 mm was measured with a minimum particle size of -35 - 200933202 and a magnification of 2 to 5 mm, and the average diameter thereof was measured. As the average particle diameter. Further, the maximum diameter of the particles contained in the 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, and two or more types may be used in combination. (mixing ratio of the additive) The light diffusing layer of the surface light diffusing polymer of the present invention is a crystalline polyester containing 50 to 99 parts by mass of the copolymerized component and 1 to 50 parts by mass and the polyester is The composition of the formulation of the incompatible additive is composed. 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 97 parts by mass of the polyester and 3 to 20 parts by mass of the additive. In addition, 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 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] -36- 200933202 (face alignment coefficient) The surface alignment coefficient (ΔΡ) of the surface light diffusing polyester film of the present invention is 0. 08~0. The 16 series are important. The lower limit of the face alignment coefficient (AP) is 〇. 〇9 is preferred, and 〇_10 is particularly good. On the other hand, the upper limit of the surface alignment coefficient (Δ P) is 〇. 1 5 is better, with 0. 1 4 is especially good. The surface alignment coefficient (ΔΡ) is 0. When it is 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-diffusing effect (surface haze) can be exerted by the surface unevenness. © Further, when the surface alignment coefficient (Δ P) is larger than 〇 · 16 , the number or size of voids generated around the additive tends to increase depending on the type of additive used. Therefore, internal scattering (internal haze) becomes large, and the total light transmittance tends to decrease. In short, the face alignment coefficient (A P) is 0. When it is 1 or less, it is possible to achieve both total light transmittance and light diffusibility. On the other hand, the face alignment coefficient is 0. When it is at least 08, it is characterized by being a biaxially stretched film, and it is excellent in heat resistance, mechanical strength, thickness uniformity, and the like, and generation of heat curl can be suppressed.方法 The method of controlling the surface alignment coefficient within the above range is arbitrary, and can be controlled, for example, by adjusting 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 component is lowered, the surface alignment coefficient can be increased. The preferred copolymerization component ratio is as described above. Further, it is also possible to control the glass transition point of the crystalline polyester containing the copolymerization component by polymer blending or copolymerization. When the glass transition point is lowered, the alignment of the biaxial stretching process described later is lowered, and the alignment coefficient of the surface -37 - 200933202 can be lowered. Further, the same effect can be obtained by lowering the inherent viscosity of the raw material polyester used in the light-diffusing layer. The preferred intrinsic viscosity is as described above. Further, the surface alignment coefficient can be controlled to some extent by adjusting the conditions of the biaxial stretching described later. In order to lower the surface alignment coefficient, the stretching temperature in the longitudinal stretching or the transverse stretching may be set to be higher, or the stretching ratio may be set lower, or the heat treatment temperature may be set higher. The preferred biaxial stretching conditions are as follows. 〇 (Optical characteristics) Next, the present invention is characterized in that the surface haze is 15% or more and the internal haze is smaller than the surface haze. Surface haze is a property derived from surface irregularities. Therefore, when light is emitted from the surface of the film or light is incident on the surface of the film, the surface haze is increased by the unevenness of the light on the surface of the light-diffusing layer. Therefore, the surface haze is basically independent of the total light transmittance. Therefore, by increasing the surface haze, the light diffusibility can be improved while suppressing the decrease in the total light transmittance. 〇 On the other hand, the internal haze is characteristic of light scattering from inside the film. Therefore, the total light transmittance is lowered due to the influence of the incident light scattering toward the back. Therefore, in order to produce a light-diffusing polyester film having excellent light diffusibility and high total light transmittance, it is an effective means for reducing the internal haze while improving the surface haze. The surface light diffusing polyester film of the present invention has a surface haze of 15% 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 preferably 60%, the upper limit is preferably 70%, and the upper limit is preferably 80%. When the surface haze is 80% or less, the internal haze can be 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 especially preferably 1%. When the internal haze is the same as the surface haze or larger than the surface haze, the internal haze becomes the main function of the light diffusion function of the film, and light scattering occurs inside the film (with rear reflection), resulting in a large total light transmittance. Reduced ground. 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%. Further, the light diffusing property of the light diffusing film can be quantitatively evaluated by, for example, sharpness of the image. The image sharpness is a sharpness index when a light source such as a fluorescent lamp is observed through a film, and the brightness is measured and evaluated according to JIS K 7 105 "Test method for optical properties of plastics" by a usual method. When the image clarity 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 sharpness of the image -39- 200933202 is preferably 1%, more preferably 3%. Further, the light diffusing property of the light-diffusing film can be further quantitatively evaluated by, for example, the transmitted light intensity by a Goniophotometer (GP-200) manufactured by Murakami Paint Co., Ltd.. The 値 of the received light intensity in the transmitted light intensity is 1 (〇), 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 is increased, so that the sharpness of the Φ image observed by the film can be lowered. Get good shielding. Further, the surface light diffusing polyester film having less uneven surface unevenness structure can densely form a surface irregular structure of a small period, and the film of such a surface uneven structure is observed at S = 3 at N = 3 degrees. There is a big tendency. The surface light diffusing polyester film of the present invention can obtain yttrium having S(l) of 75% or more and S(3) of 30% or more. 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. Further, when the 値 of S(3) is less than 30%, φ may cause a problem of so-called ripple or flicker depending on the combined lens sheet, enamel sheet, liquid crystal panel, or the like, which is not preferable. S(N) = 1(N)/I(0)xl00 Further, although the light transmittance is higher as the transmitted light intensity is larger, when the transmitted light intensity is more than necessary, there are many cases where I(0) is lowered. As a result, the brightness of the front side of the backlight module is lowered. In the surface light-diffusing polyester film of the present invention, the upper limit S of S (1 ) is preferably 99%, more preferably 95%, and even more preferably 85%. For the same reason, the upper limit of S(3) is preferably 50%, preferably 45%, and more preferably 40%. (Mechanical Properties) -40-200933202 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 3% or less in the transverse direction and the longitudinal direction, and the preferred upper limit is 2. 5%, the upper limit is 2%, and the upper limit is 1. 5%, the more excellent 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 can be used in high-temperature processing or 0 in a high-temperature environment, and the dimensional change or planarity does not deteriorate, and good flatness 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 the flow direction (winding direction) of the film at the time of film formation, and the longitudinal direction means the direction perpendicular thereto. Further, the lower limit of the tensile strength of the film is preferably 100 MPa, more preferably 130 MPa, and particularly preferably 160 MPa. When the tensile strength is 100 MPa or more, the tensile strength of the mechanical strength of the biaxially stretched film can be exhibited, and defects such as breakage, cracking, breaking, and cracking are less likely to occur in the film processing process. φ Further, the thickness of the surface light diffusing polyester film of the present invention is not uniform. Below 0% is preferred. The thickness of the film is not 5. When it is 0% or less, when the film is wound on a roll, wrinkles or bulging are less likely to occur, and flatness can be maintained. As a result, in the backlight panel module, the brightness of the light exit surface becomes uniform, and the original purpose of the light diffusing film can be achieved. Further, the surface light diffusing polyester film of the present invention preferably has a crimp entanglement of 5 mm or less after heat treatment at 100 ° C for 30 minutes in a no-load state. • 41 - 200933202 When the crimp entanglement is 5 mm or less, for example, when the final product is incorporated as a light-diffusing film, the handleability is good when the work is performed without stretching. Further, even in the case of high-temperature processing or high-temperature use, it is possible to suppress the occurrence of film deformation, and it is possible to achieve the original purpose of the light-diffusing film in which the brightness of the light-emitting surface is uniform in the backlight module. The suppression of the curl can be adjusted by controlling the difference in melting point between the support layer (A) and the light diffusion layer (B) as described above, and in order to control the film caused by the difference in cooling rate due to the cooling of the front and back by pressing. The degree of crystallization in the thickness direction is the initial curl, and the curl caused by the structural difference between the front and back of the film imparted in various processes such as preheating, stretching, cooling, and winding, to apply a structure that actively produces a film back. The difference, and the structural difference of the inevitability complement each other to make the curl 値 close to zero. Specifically, the temperature of the back of the film or the heat is different by the stretching process and the heat treatment process such as longitudinal stretching or transverse stretching, and the orientation of the film back is independently controlled and the film is used. The structure of the back or the condition of the physical properties to achieve zero curl film formation. φ Further, in order to be a basic condition capable of stable production in a low-wrinkle state across the full width range, it is also important to use a stretching prescription having less thickness unevenness. More specifically, for the longitudinal crimping immediately after film formation, the structural difference of the film back surface when longitudinal stretching is controlled, and the lateral crimping is controlled by the structural difference of the film back surface when transverse stretching and heat setting are controlled, The internal strain in the opposite direction is made to have the internal strain caused by the structural difference of the inevitable film back, so that the curl is preferably suppressed. Further, the thickness of the surface light diffusing polyester film of the present invention is arbitrary, and -42 to 200933202 is not particularly limited, and is preferably in the range of 25 to 500 μm to be in the range of 7 5 to 3 5 μm. Better. (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 ( In the following, there is also a representative example of particles in the case of a poly(ethyl ester). The transfer of the above-mentioned particles is usually carried out by air transportation using a predetermined pipe, in case of prevention. It is better to use dust in the dust to use the ΗΕΡΑ filter and use cleaned air. The ΗΕΡΑ filter used at this time is to use the nominal filtration accuracy to have a retention of more than 95%. A filter having a performance of dust of 5 micrometers or more is preferred. 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 make the water content of less than 100 ppm. Next, each raw material was measured and mixed, supplied to an extruder, and melt-extruded into a sheet shape. Further, an electrostatic application method is used to adhere a sheet in a molten state to a rotating drum (cold drum) made of metal having a controlled surface temperature of 10 to 50 ° C, and blowing cold air from the opposite surface to be cooled and solidified. Unstretched PET sheets. In the present invention, among the raw materials, it is important to use a premixed mother particle in which all or a part of the base polymer and the incompatible additive are melt-mixed in advance using an extruder. At this time, the temperature of the resin from the melted portion of the extruder, the kneading section, the polymer tube, the -43-200933202 gear pump, and the filter is controlled to 220 to 290 ° C, and the subsequent polymer tube is used. The resin temperature of the die is controlled to be 210 to 29 5 ° C, and it is preferable because the generation of foreign matter such as deteriorated substances can be suppressed. Further, the molten resin is subjected to high-precision filtration at a position which can be maintained at a constant temperature of 2 7 5 t to remove foreign matter contained in the resin. The filter material used for the high-precision filtration of the molten resin is excellent in the performance of removing the aggregate of Si, Ti, Sb, Ge, and Cu as a main component or the organic compound having a high melting point in the resin, and it is preferable to use a stainless steel sintered body. When the temperature of the molten resin is less than 275 °C, the amount of discharge of the raw material resin is lowered due to an increase in the filtration pressure. . > Further, the filter particle size (initial filtration efficiency: 95%) of the filter medium is 20 μm or less, preferably 15 μm or less. When the filter particle size (initial filtration efficiency: 95%) of the filter medium is more than 20 μm, it is difficult to sufficiently remove foreign matter larger than 20 μm. By using a filter material having a filtered particle size (initial filtration efficiency of 95%) of 20 μm or less, high-precision filtration of the molten resin is performed, and although productivity is lowered, the optical defects are small in order to obtain coarse particles. The film is an important process. Further, in the present invention, by using a thermoplastic resin which is incompatible with the crystalline copolyester as an additive, the above-described high-precision filtration becomes possible. In order to co-extrude and laminate the light-diffusing layer (B) and the support layer (A), two or more extruders are used to extrude the raw materials of the respective layers, and a multi-layer supply block is used (for example, having a square shape) The confluent portion of the merging portion is used to join the two layers, and is extruded into a sheet shape from a slit-like die, and is cooled and solidified on a casting drum to produce an unstretched film. Alternatively, a multi-tube die can be used instead of a multi-layer 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 of the surfaces, and it is more preferable to have a coating layer on both surfaces. The preferred amount of coating after drying is in the range of 〇·〇〇5~〇·20 g/m 2 . By providing the coating layer on the surface of the light diffusion layer, it is possible to suppress the generation of reflected light on the surface of the film, and it is possible to further increase the total light transmittance. Further, when a coating layer is provided on the surface opposite to the light-diffusing layer, and the surface of the coating layer is subjected to ruthenium sheet processing or hard coating processing, adhesion can be imparted. At this time, the untwisted film obtained by the above method was coated with a ruthenium layer, and then biaxially stretched. It may be simultaneous biaxial stretching or sequential biaxial stretching. When it is carried out by the sequential stretching method, the film is uniaxially stretched in the longitudinal or transverse direction, and the adhesive layer is disposed in the orthogonal direction. Stretch to perform biaxial stretching. The method of applying the coating liquid for forming a coating layer to an unstretched film or a uniaxially stretched film can be selected from any known methods, and examples thereof include a reverse roll coating method, a gravure coating method, an anastomotic coating method, and a die coating method. The method, the roll brush method, the spray coating method, the pneumatic blade coating method, the wire bar coating method, the tube scraping Φ knife method, the dip coating method, the curtain flow coating method, and the like, and the methods may be applied singly or in combination. From the viewpoint of ensuring better adhesion to other optical functional layers in the use of a ruthenium sheet or a light diffusing film, the resin constituting the coating layer is a copolymerized polyester resin, a polyurethane resin, It is preferable that at least one or more kinds of acrylic resins are used as a main component. Further, these resins are also recommended from the viewpoint of suppressing 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 100% by mass, and at least i of the resin contains -45 to 2009332025% by mass or more. Further, in order to improve the transparency of the film, if the support layer does not contain particles or contains only particles which are not inhibited from transparency, the slipperiness of the film becomes insufficient, and the handleability is deteriorated. The situation. Therefore, in the above coating layer, it is preferred to contain particles for the purpose of imparting slipperiness. In order to ensure transparency, it is important that these particles use particles having a very small average particle diameter below the wavelength of visible light. Examples of the particles include inorganic particles such as calcium carbonate, calcium phosphate, cerium oxide, kaolin, talc, titanium oxide, 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 mainly by the above-mentioned copolymerized polyester resin, 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 by the number of SEM observations) is 0. 005-1. 0 micron. In order to ensure the transparency, handleability and scratch resistance of the film, the upper limit of the average particle diameter of the particles is 0. 5 microns is better, with 0. 2 microns is especially good. Further, in terms of handleability and scratch resistance, the lower limit of the average particle diameter of the particles is 0. 01 micron is better, to 〇. 〇 3 microns is especially good. 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 -46-200933202 of 300 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 transmission electron microscope (TEM) is used to take a cross section of the coated film at a magnification of 2 to 5 mm, and the presence of the cross section of the coated film is obtained. 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 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 0. 1 to 60% by mass is preferred. In terms of transparency and adhesion, the upper limit of the particle content is preferably 50% by mass, and 40% by mass. , especially good. Further, in terms of handleability and scratch resistance, the lower limit of the particle content is more preferably 1% by mass, and is 0. 5% by mass is particularly good. 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. © Next, the unstretched film obtained according to the above method is simultaneously biaxially stretched or sequentially biaxially stretched, followed by heat treatment. The above biaxial stretching is in the longitudinal and transverse directions by 2. It is important to carry out the stretching ratio of 8 times 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. The stretching ratio of either the longitudinal direction or the transverse direction is less than 2. At 8 times, the thickness unevenness of the obtained film was lowered, and the biaxially stretched film was originally incapable of obtaining excellent heat resistance and mechanical strength. Further, the thickness uniformity of the film is remarkably deteriorated. The lower limit of the preferred draw ratio in the present invention is 3. 0 times' better 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) Intrinsic viscosity According to JIS K 7367-5, the solvent is a mixture of phenol (60% by mass) and 1,1,2,2-tetrachloroethane (4 〇 by mass). The agent was measured at 3 ° C. (2) Crystal melting heat, melting point, and glass transition temperature were determined using a DSC6220 differential scanning calorimeter manufactured by SIINano Technology. The resin sample was heated and melted at 300 ° C for 5 minutes in a nitrogen atmosphere, and then rapidly cooled with liquid nitrogen, and 10 mg of the pulverized resin sample was heated at a rate of 20 ° C /min, and differential heat was applied. Analysis. The heat of crystal melting is in accordance with JIS-K7 1 2 1 - 1 987, 9. The DSC curve surrounding the melting peak temperature (Tpm), the extrapolation melting start temperature (Tim), and the extrapolation melting end temperature (Tem) defined by the first item is obtained by integrating the DSC curve. Further, the melting peak temperature (Tpm) was taken as the melting point. Moreover, according to JIS-K7 121-1987, 9. 3 items to find the glass transition temperature (Tg). (3) Melt viscosity The viscosity of the resin sample is based on the standard of ISO K 7199 "Test method for plastic flow characteristics of plastic capillary rheometers and slot die rheometers". 1. Method A (capillary die) of 3 items was used for measurement. Using a Toyo Seiki-48-200933202 CAVIROGRAPH 1B and using a capillary die of φΐmm, L/D = 10, the dried resin sample was filled in a cylinder maintained at 270 °C, and melted for 1 minute. At a cutting speed of 608. The melt viscosity was measured under OsecT1. Further, when a plurality of kinds 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 filled in a cylinder, and measured by the same method as described above. Melt viscosity. (4) Uneven thickness of the film The continuous tape-shaped sample having a length of 3 mm in the transverse direction and a length of 5 cm in the longitudinal direction was taken up, and the film thickness was measured using a film thickness continuous measuring machine (manufactured by Anritsu Co., Ltd.), and recorded. In the logger. The maximum thickness d (dmax), minimum 値 (dmin), and average 値 (d) of the thickness were obtained from the graph, and the thickness unevenness (%) was calculated in accordance with the following. Further, when the length of the lateral direction is less than 3 m, they are joined together. Also, the connection portion is deleted from the above data. Thickness unevenness (%) = ((dmax) - (dmin) / d) xl00 The measurement was performed three times and the average enthalpy was determined, 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 haze (turbidity) and total light transmittance are based on JIS K 7105 The test method for optical properties of plastics is measured. The film length direction of the film test piece was set to the vertical direction, and the light diffusion layer (B) surface was set to face the light source side, and was measured using a NDH-300A type turbidity meter manufactured by Nippon Denshoku Industries Co., Ltd. (6) Internal haze, total haze, surface haze-49- 200933202 Two pieces of cedar oil will be coated on both sides of the film test piece (coating amount: 20±10 g/m2 per side), and the haze is A highly transparent polyethylene terephthalate film (for example, 'made by Toyobo Co., Ltd., A4300, thickness 1 〇〇 micron) which is less than 1% by weight is used as a sample for internal haze measurement. Further, two sheets of the highly transparent polyethylene terephthalate film were laminated with cedar oil as a blank sample. Next, the haze of the sample for internal haze measurement and the blank sample was measured in accordance with the method described in (5). Then, the internal haze is 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 by 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 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 tester used the ICM-1T image sharpness tester manufactured by SUGA Test Machine Co., Ltd. (8) Light diffusibility The light diffusivity was measured using a Goniophotometer (GP-200) manufactured by Murakami Color Technology Research Institute. The light source is a halogen lamp (12 V, 50 W), 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 filtered by ND having a transmittance of 1%. The light is used for dimming. The light source beam aperture is 10. 5 mm, the light receiving aperture of the receiver is 9. 1 mm. The film test piece was attached to the sample holder in such a manner that the surface of the 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 -50-200933202 was up-and-down. The light source beam is extended in the direction of the coaxial light by 0 degrees, 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. The transmitted light intensity was measured in the range of -80 degrees to +80 degrees on a 1 degree scale. When the transmitted light intensity at an angle of 0 degrees measured according to the above method is 1 (0) and the transmitted light intensity at an angle of ±N degrees is taken as I (N), the transmitted light obtained according to the following calculation formula is used. The intensity ratio S(N) [%] is used as an indicator of light diffusing enthalpy. In the present invention, s(1) is used, which is identified as being related to the sharpness of the image observed by the light diffusing film, and S(3) is used as being recognized and incorporated into the liquid crystal display. Corrugated or flashing related cockroaches. S(N) = I(N)/I(0)x 1 00 (9) Light distribution unevenness The light distribution unevenness of the light-diffusing film was evaluated by the following method. The light-diffusing film was placed with the light-diffusing layer facing up on the glass slide and fixed by overlapping the glass cover sheets. Using an optical microscope (5 times for the object and 1× for the eye) and observing with a transmission light source, when the focus is adjusted from the upper surface of the light diffusion film and the focus is adjusted to the convex portion, the uniform distribution of light and dark is evaluated as 〇, not The uniformity is X. (10) Tensile strength according to JIS C 2 3 1 8- 1 997 5 . 3. 3 (tensile strength and elongation) to measure. (11) Dimensional change rate Measured in accordance with JIS C 2318-1 997 5·3·4 (dimension change rate). -51- 200933202 (12) Surface alignment coefficient (△ P) According to 118〖714 2- 1 99 6. 5. 1 (eight methods) 'The refractive index (nx) in the longitudinal direction of the film, the refractive index (ny) in the width direction, and the refractive index (nz) in the thickness direction are measured by using an abundance line as a light source, and by an Abbe refractometer. The surface alignment coefficient (ΔΡ) was calculated according to the following formula. Δ P = (nx + ny) / 2 - nz (13) Curly 値 The film was cut into a sheet shape of 100 mm in the longitudinal direction and 50 mm in the transverse direction, and was heat-treated at 1 ° C for 30 minutes in an unloaded state. , so that the convex portion of the film faces down and rests on the horizontal glass plate, using the ruler and with a minimum scale of 0. The vertical distance between the glass plate and the lower ends of the four corners of the raised film was measured in 5 mm units to determine the average enthalpy of the measurement at the four positions. 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 〇 Example 1 (1) Manufacture of crystalline homopolyester resin (Μ 1 ) The temperature of the esterification reactor is raised, and when it reaches 200 ° C , joined by 86. 4 parts by mass of citric acid and 64. 4 parts by mass of a slurry of ethylene glycol, and added 0 while stirring. 017 parts by mass of antimony trioxide and 0. 16 parts by mass of triethylamine. Then, the pressure is raised, and the gauge pressure is 3. Under the conditions of 5 kgf/cm2 and 240 ° C, a pressure esterification reaction was carried out. Subsequently, the normal pressure is restored in the esterification reaction tank, and 0. 071 parts by mass of magnesium acetate tetrahydrate, followed by 0. 014 parts by mass of trimethyl phosphate. And the temperature was raised to 260 ° C in 15 minutes, adding 0. 012 mass -52- 200933202 parts of trimethyl phosphate, followed by 0. 0036 parts by mass of sodium acetate. After 15 minutes, the obtained esterification reaction product was transferred to a polycondensation reaction tank, and the temperature was gradually raised from 260 ° C to 280 ° C under reduced pressure, and the polycondensation reaction was carried out at 285 ° C until the prescribed value was reached. Inherent viscosity. 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 crystallization crystalline homopolyester resin (Ml) has a crystal heat of fusion of 35 mJ/mg, a melting point of 256 ° C, and an intrinsic viscosity of 0. 56dl/g, melt viscosity of 91Pa·s, Sb content of 144ppm, Mg content of 58ppm, P content of 々Oppm. , color L値 is 56. 2. The color b値 is 1. 6. Further, substantially no inert particles and internal precipitated particles are contained. (2) Production of copolymerized polyester resin (M2) with 100 mol% decanoic acid unit as aromatic dicarboxylic acid component, 70 mol% ethylene glycol and 30 mol% neopentyl glycol as diol component , according to the manufacturing method of (Ml) © to produce an intrinsic viscosity of 0. 59 dl / g, a copolymerized polyester resin (M2) having a melt viscosity of 121 Pa «s. (3) Styrene (M3) A polystyrene resin (PS) having a melt viscosity of 147 Pa·s was used. (4) Preparation of immiscible additive premixed masterbatch (Μ B 1 ) will be 70. 0% by weight of crystallization at 135t under reduced pressure for 6 hours (1 Torr) after the crystalline homopolymer resin (Ml) and 30. 0% by weight of polystyrene (M3) was mixed with particles and supplied to a temperature adjusted to 285. (: The twin-screw extruder, and mixing and extruding at a rate of 50 rpm, a discharge of about 7.5 kg per hour, and a retention time of -53-200933202 in the extruder for about 6 minutes, and The obtained strands are cooled and cut to prepare a non-cohesive additive premixed mother particle (MB1). (5) Preparation of coating liquid (M4) 95 parts by mass of dimethyl phthalate and 95 parts by mass of isoindole Dimethyl acrylate, 35 parts by mass of ethylene glycol, 145 parts by mass of neopentyl glycol, 0. 1 part by mass of zinc acetate and bismuth. One part by mass of antimony trioxide was added to the reaction vessel, and the ester exchange reaction was carried out at 180 ° C for 3 hours. Then, add 6. 0 parts by mass of 5-sodium sulfonate isophthalic acid, after esterification reaction at 240 ° C for 1 hour, under reduced pressure at 250 ° C (1 〇 ~ 0. 2 ® mm Hg), a polycondensation reaction was carried out for 2 hours to obtain a copolymerized polyester resin having a number average molecular weight of 19,500. Will be 7. 5 parts by mass of the obtained copolymerized polyacetate, a 30% by mass aqueous dispersion of the resin, 11. 3 parts by mass of a 20% by mass aqueous solution of a self-crosslinking type polyurethane resin containing an isocyanate group, which is a block of sodium hydrogen sulfite, 0. 3 parts by mass of organotin-based catalyst, 39. 8 parts by mass of water and 37. 4 parts by weight of isopropyl alcohol were mixed. Also, add 0. 6 parts by mass of a fluorine-based nonionic surfactant, 10% by mass aqueous solution, 2. 3 parts by mass of a colloidal cerium oxide of particle A (average particle diameter: 40 nm) of 20% by mass aqueous dispersion, hydrazine. 5 parts by mass of dry B method of particle B (average particle size 200 nm, average primary particle size 40 nm) 3 . 5 mass% aqueous dispersion. Next, the pH of the coating liquid was adjusted to 6.2 ′ using a 5% by mass aqueous solution of sodium hydrogencarbonate, and precision filtration was performed using a digital polypropylene filter having a filter particle size (initial filtration efficiency: 95%) of 1 μm. To adjust the coating liquid (M4). (6) Production of surface light diffusing polyester film 33. Raw material of light diffusing layer (B). 4% by mass at 135 ° C under reduced pressure -54 - 200933202 (1 Torr) 6 hours after the crystalline homopolymer (Ml), 33. 3 mass% of the copolymerized polyester (M2) and 33 after drying under reduced pressure (1 Torr) at 70 ° C for 12 hours. 3 mass% Polystyrene premixed mother particles (MB 1) after 6 hours of drying under reduced pressure (1 Torr) at 135 ° C were mixed and supplied to the extruder 2. Further, the crystalline terpolymer (M1) of the raw material of the support layer (A) was dried under reduced pressure (1 Torr) at 135 ° C for 6 hours, and supplied to the 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 27 5 ° C, and the set temperature of the polymer tube © after the filter was 270 ° C. Each of the raw materials supplied from the extruder 2 and the extruder 1 was laminated using two layers of confluent blocks, and melt-extruded from the nozzle sheets. Further, in the layers (A) and (B), the thickness ratio was controlled by using a gear pump of each layer so as to be 80 to 20. Further, in the above filter, any of the filters using a stainless steel sintered body (nominal filtration accuracy: 95% of 10 μm particles are retained). 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 〇 ° C by an electrostatic application method 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. Also, the cooling drum pulled the unstretched film at a speed of 12 meters per minute. The obtained unstretched film was heated to 77 ° C ' using a preheating roll and stretched by 3.4 times in the longitudinal direction by the 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 in such a manner that the maximum temperature of the film was 100 °C. After the longitudinal stretching is completed, the obtained uniaxially stretched film is cooled to 50 ° C, and the coating liquid (M4) is applied to both sides of the film. The coating amount of both coatings is -55-200933202 each is about 15 g/square. The way of the meter is controlled. Subsequently, the coated surface was dried using a drying oven. The both ends of the uniaxially stretched film having the coating layer were held by a clip and guided to a tenter, preheated to 120 ° C, and stretched at 135 ° C in the width direction. After 5 times, it is stretched in the width direction at 140 °C. 6 times, further heat treatment at 240 ° C for 10 seconds, and in the process of cooling to 60 ° C in the width direction 3. A 3% relaxation treatment was carried out to prepare a surface light diffusing polyester film having a total thickness of 1 μm. Further, in order to measure the melting point and the intrinsic viscosity of the polyester of each layer, the (A) layer of the unstretched film alone was temporarily stopped by the discharge of the layer (B). Similarly, the discharge of the (A) layer is temporarily stopped to take a separate unstretched film of the (B) layer. - (7) Film characteristics The film properties obtained in Example 1 are shown in Table 1. Further, the observation image of the light distribution unevenness of the film obtained in the first embodiment is as shown in Fig. 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 accuracy which are originally excellent for the biaxially stretched film. Also, the internal haze is small and has a high light transmittance. Further, most of the total haze is imparted by the surface haze, and the image sharpness is small, and s(l) is large, and the concealability is excellent. Further, it can be seen from Fig. 1 that there is no unevenness in light distribution, and it is known that s(3) is large, and it is known that generation of ripples or flicker can be suppressed. Example 2 except as a raw material for the light diffusion layer (B). 2% by mass of crystallization at 135 ° C under reduced pressure for 6 hours (1 Torr) after the crystalline homopolymer (Ml), 19. 8% by mass of the copolymerized polyester (M2) after drying under reduced pressure at 70 ° C for 12 hours (1 Torr) and 50% by mass of polystyrene after drying under reduced pressure (1 Torr) at 135 ° C for 6 hours The pre-mixed mother particles (MB1) are mixed and supplied to the extruder 2, and the support layer (A) is -56-200933202 raw material 76. 7 parts by mass of the crystalline homopolymer (Ml) and 23. After drying at 135 ° C under reduced pressure (1 Torr) for 6 hours. 3 mass% of the copolymerized polyester (M2) after drying under reduced pressure at 70 ° C for 12 hours (1 Torr) was supplied to the extruder 1, and the thickness ratio of the layers (A) and (B) was controlled to 90 to 1 〇, and the temperature at which the preheating roll is heated at the time of stretching in the flow direction is 79 ° C, and the coating liquid (M4) is applied only to the surface side of the support layer (A) side, and is used. The surface light diffusing polyester film of Example 2 was produced in the same manner as in Example 1. The film properties obtained in this Example 2 are shown in Table 1. From Table 1, it is understood that the second embodiment has excellent characteristics similarly to the first embodiment. Example 3 In addition to 42 as a raw material of the light diffusion layer (B). 5 mass% at 13 5 ° C under reduced pressure for 6 hours (1 Torr) after the crystalline homopolymer (Ml), 20. 8 mass % of copolymerized polyester (M2) and 36 after 7 hours of TC drying under reduced pressure for 12 hours (1 Torr). 7 mass% of polystyrene premixed mother particles (MB 1 ) after 6 hours of drying under reduced pressure (1 Torr) at 135 t, and supplied to the extruder 2, and the film thickness after stretching was 188 μm. The method is to adjust the pulling speed of the unstretched film Q by cooling the drum, and the raw material of the support layer (A) is 76. 7 parts by mass of crystalline homopolymer (Ml) and 23. after 135 ° (: drying under reduced pressure (1 Torr) for 6 hours. 3 parts by mass of the copolymerized polyester (M2) after drying under reduced pressure at 70 ° C for 12 hours (1 Torr) and supplied to the extruder, and the thickness ratio of the layers (A) and (B) was controlled to 8 9 to 1 1, and stretched in the direction of flow 3. 3 times and stretched in the width direction at 1 3 5 °C. After 4 times, it is stretched in the width direction at 140 ° C. 6 times, further heat-treated at 240 ° C for 17 seconds, and a relaxation treatment of 1.3 % in the width direction during cooling to 60 ° C, and a thickness of 188 μm was produced in the same manner as in Example 1. Surface light diffusing polyester-57-200933202 film of Example 3. The film properties obtained in this Example 3 are shown in Table 。. It is understood from Table 1 that the third embodiment has excellent characteristics similarly to the first embodiment. Example 4 The heat treatment was carried out at 235 ° C for 17 seconds except for the stretching in the width direction, and the relaxation treatment of 〇 8 % in the width direction was carried out in the process of cooling to 60 ° C, and the same procedure as in Example 3 was used. The method of producing the surface light diffusing polyester film of Example 4 was carried out. The film properties obtained in this Example 4 are shown in Table 1. It is understood from the above that the fourth embodiment has excellent characteristics similarly to the first embodiment. Example 5 The heat treatment was carried out at 235 ° C for 17 seconds except for stretching in the width direction, and was carried out in the width direction during cooling to 60 ° C. The surface light diffusing polyester film of Example 4 was produced in the same manner as in Example 3 except for the 3% relaxation treatment. The film properties obtained in this Example 5 are shown in Table 1. From Table 1, it is understood that Example 5 has excellent characteristics similarly to Example 1. Comparative Example 1 In addition to 60 parts by mass of the raw material of the light-diffusing layer (B), the crystalline homo-polyester (M1) and 30 parts by mass at 70 ° C after drying under reduced pressure at 135 ° C for 6 hours (1 Torr) The copolymerized polyester (M2) after drying under reduced pressure for 12 hours (1 Torr) and 10 parts by mass of polystyrene (M3) were mixed and supplied to the extruder 2, and 100 parts by mass of the raw material of the support layer (A) was added. The crystallized homopolyester (M1) was dried at 135 ° C for 6 hours, and the crystalline homopolymer (M1) was supplied to the extruder 1, and the surface light diffusion of Comparative Example 1 was produced in the same manner as in Example 1. Sexual polyester thin -58- 200933202 film. The film properties obtained in Comparative Example 1 are shown in Table 1. Further, the observation chart of the light distribution unevenness of the film obtained in Comparative Example 1 is shown in Fig. 2. As can be seen from Fig. 2, since the film of Comparative Example 1 can observe uneven light distribution (approximately 400 μm) between liquid crystal panels of full HD, it is easy to generate so-called ripple or flicker. The display quality is low. Comparative Example 2 ® In addition to 65 as a raw material for the light diffusion layer (B). 2 parts by mass of crystalline homopolymer (Μ 1), 1 after drying at 135 ° C for 6 hours (1 Torr). 8 parts by mass of the copolymerized polyester (M>2) and 15 parts by mass of polystyrene (M3) after drying under reduced pressure at 70 ° C for 12 hours (1 Torr), and supplied to the extruder 2 for use. The same method as shown in Example 2 was carried out to produce a surface light diffusing polyester film. The film properties obtained in Comparative Example 2 are shown in Table 1. Comparative Example 3 <Production of Copolymerized Polyester Resin (M5)> 100 mol% to citric acid unit of the aromatic dicarboxylic acid component, 70 mol% ethylene glycol unit of the diol component, and 30 mol% of cyclohexene The alkane dimethanol unit was used as a constituent component to produce a crystalline copolymerized polyester resin (M5) having an intrinsic viscosity of 0.60 dl/g and a melt viscosity of 197 Pa*s. In addition to 40 parts by mass of the raw material of the light-diffusing layer (B), the crystalline homopolyester (mi) and 40 parts by mass were dried at 70 ° C under reduced pressure at 135 ° C for 6 hours (1 Torr). The copolymerized polyester (M5) and 20 parts by mass of polystyrene (M3) after 12 hours (1 Torr) are mixed and supplied to the extruder 2, and will support 50 of the raw material of the layer -59-200933202 (A). The copolymerized polyester of the crystalline portion of the crystalline homopolymer (Ml) and 50% by mass after drying at 135 ° C for 6 hours under reduced pressure at 70 ° C for 12 hours (1 Torr) M2) The surface light diffusing polyester film of Comparative Example 3 was produced by the same method as that described in Comparative Example 2, except that it was mixed and supplied to the extruder 1 and further heat-treated at 235 °C after the transverse stretching. The film properties obtained in Comparative Example 3 are shown in Table 1. Comparative Example 4 A surface light diffusing polyester film of Comparative Example 4 was produced in the same manner as in Comparative Example 2 except that the coating liquid (M4) was applied to both surfaces of the film. The characteristics of the film obtained in Comparative Example 4 are shown in Table 1. Comparative Example 5 The thickness ratio of the (A) layer and the (B) layer was controlled to 96 to 4, except that the pulling speed of the unstretched film was adjusted by cooling the drum so that the film thickness after stretching was 250 μm. The temperature in the flow direction was 79 ° C by the preheating roll, and it was stretched 3.3 times in the flow direction and 2.4 times in the width direction of the 135 ° C, and then pulled in the width direction at 140 ° C. The film was heat-treated at 240 ° C for 22 seconds, and further cooled to 6 (the process of TC was performed by 1.3% relaxation in the width direction, and the same method as in Comparative Example 1 was used to produce a thickness of 250 μm. The surface light diffusing polyester film of Example 5. The characteristics of the film obtained in Comparative Example 5 are shown in Table 1. Comparative Example 6 except that 69 parts by mass of the material as the light diffusion layer (B) was reduced at 135 ° C Copolymerized polyester (M2) after pressure drying for 6 hours (1 Torr), crystalline homopolymer (Μ 1 ), 21 mass -60 - 200933202 parts, dried under reduced pressure at 70 ° C for 12 hours (1 Torr) And 10 parts by mass of polystyrene (M3) are mixed and supplied to the extruder 2, and the thicknesses of the layers (A) and (B) are The surface light diffusing polyester film of Comparative Example 6 was produced in the same manner as in Comparative Example 5 except that the ratio was 90 to 10. The film properties obtained in Comparative Example 6 are shown in Table 1. Comparative Example 7 62 parts by mass of the raw material of the light-diffusing layer (B) was dried under reduced pressure at 135 ° C for 6 hours (1 Torr), and the crystalline homopolyester (M1) and 31 parts by weight were dried under reduced pressure at 7 ° C. After 12 hours (1 Torr), the copolymerized polyester (M2) and 7 parts by mass of polystyrene (M3) were mixed and supplied to the extruder 2, and the coating liquid (M4) was only coated on the support layer (B). The surface light diffusing polyester film of Comparative Example 7 was produced in the same manner as in Example 5 except for the side of the side. The film properties obtained in Comparative Example 7 are shown in Table 1. Comparative Example 8 58.9 parts by mass of the raw material of the light-diffusing layer (B) was dried under reduced pressure at 135 ° C for 6 hours (1 Torr), and then dried under reduced pressure at 70 ° C for 12 hours. (1 Torr), the copolymerized polyester (M2) and 7 parts by mass of polystyrene (M3) are mixed and supplied to the extruder 2, and the layer (A) is The surface light diffusing polyester film of Comparative Example 8 was produced in the same manner as in Example 3 except that the thickness ratio of the layer (B) was controlled to be 84 to 16. The film properties obtained in Comparative Example 8 are as shown in Table 1. Comparative Example 9
除了將作爲光擴散層（B)的原料之57質量份在135 °C -61 - 200933202 減壓乾燥6小時（1托）後之結晶性同元聚酯（Ml)、38質量 份在70°C減壓乾燥12小時（1托）後之共聚合聚酯（M2)及5 質量份聚苯乙烯（M3)混合，並供給至擠壓機2以外，使用 比較例8所示同樣的方法來製造比較例9的表面光擴散性 聚酯薄膜。 本比較例9所得到薄膜特性係如表1所示。 比較例1 0〜1 2 除了以（A)層和（B)層的厚度比率爲89對11的方式來 Ο 控制各擠壓機的齒輪’並以表1所記載之條件進行縱向拉 伸、塗布 '橫向拉伸、熱處理以外，使用比較例9所示同 樣的方法來製造比較例10〜12的表面光擴散性聚酯薄膜。 本比較例1 〇〜1 2所得到薄膜特性係如表1所示。 從表1，得知本比較例1〜1 2具有與實施例1〜4同樣 優良的力學特性、尺寸安定性、厚度均勻性，且s (1)亦顯 示大的値，具有優良的光擴散薄膜之特徵，但是由於S (3) 小於30，或是大於50，亦能夠觀察到表面結構的凹凸不 φ 均，所以組入高精細的液晶顯示器時，有產生波紋或閃爍 等的問題之可能性。 參考例1 除了將作爲光擴散層（B)的原料之85質量份在135 t 減壓乾燥6小時（1托）後之結晶性同元聚酯（Ml)及15質量 份聚苯乙烯（M3)混合，並供給至擠壓機2,且將光擴散層（A) 的原料之100質量份在135 °c減壓乾燥（1托）6小時後之結 晶性同元聚酯（Ml)供給至擠壓機1以外，使用比較例2所 示同樣的方法來製造參考例1的光擴散性聚酯薄膜》 -62- 200933202 本參考例1所得到薄膜特性係如表1所示。本參考例 1的薄膜在光擴散層內部具有許多空隙，因爲內部霧度對 總霧度的貢獻大致使總光線透射率變小，認爲組入液晶顯 示器時會產生亮度大幅度降低。 參考例2 將作爲光擴散層（B)的原料之24質量份在135°C減壓 乾燥6小時（1托）後之結晶性同元聚酯（Ml)、66質量份在 70 °C減壓乾燥12小時（1托）後之共聚合聚酯（M2)及10質量 份聚苯乙烯（M3)混合，並供給至擠壓機2。又，將光擴散 ® 層（A)的原料之1〇〇質量份在135°C減壓乾燥（1托）6小時後 之結晶性同元聚酯（Ml)供給至擠壓機1。以（A)層和（B)層的 厚度比率爲90對10的方式來控制各擠壓機的齒輪。以拉 伸後的薄膜厚度爲25 0微米的方式藉由冷卻轉筒調整未拉 伸薄膜的牽引速度。在將未拉伸薄膜往流動方向縱向拉伸 時，使藉由預熱輥之加熱溫度爲75 °C且在不同周速的輥間 縱向拉伸3.3倍。此時，以在拉伸區間之薄膜的最高溫度 爲9(TC的方式來控制近紅外線加熱器溫度。 @ 將塗布有塗布層之雙軸拉伸薄膜的兩端使用夾子把持 並引導至擴幅機且在90°C預熱後，於95°C在寬度方向拉伸 2.5倍後，於95 °C在寬度方向拉伸1.6倍，進而於223 °C熱 處理22秒，且在冷卻至60°C之過程在寬度方向進行1.3% 的鬆弛處理。 除上述以外，使用實施例1所示同樣的方法來作成參 考例2之總厚度爲25〇微米的表面光擴散性聚酯薄膜。 本參考例2所得到薄膜特性係如表i所示。本參考例 2的薄膜之面配向係數小、尺寸安定性差，且卷曲値大。 因爲所得到薄膜的卷曲激烈而無法評價熱尺寸安定性。 -63- 200933202In addition to the 57 parts by mass of the raw material of the light-diffusing layer (B), the crystalline homo-polyester (Ml) and 38 parts by mass were dried at 135 ° C -61 - 200933202 under reduced pressure for 6 hours (1 Torr) at 70 °. C was dried under reduced pressure for 12 hours (1 Torr), and then copolymerized polyester (M2) and 5 parts by mass of polystyrene (M3) were mixed and supplied to the extruder 2, and the same method as in Comparative Example 8 was used. The surface light diffusing polyester film of Comparative Example 9 was produced. The film properties obtained in Comparative Example 9 are shown in Table 1. Comparative Example 1 0 to 1 2 The gears of each of the extruders were controlled so that the thickness ratio of the layers (A) and (B) was 89 to 11, and longitudinal stretching was performed under the conditions described in Table 1, The surface light diffusing polyester film of Comparative Examples 10 to 12 was produced in the same manner as in Comparative Example 9 except for the application of the transverse stretching and the heat treatment. The film properties obtained in Comparative Example 1 〇~1 2 are shown in Table 1. From Table 1, it is found that Comparative Examples 1 to 1 2 have excellent mechanical properties, dimensional stability, and thickness uniformity as in Examples 1 to 4, and s (1) also exhibits large enthalpy and excellent light diffusion. The characteristics of the film, but since S (3) is less than 30 or greater than 50, the unevenness of the surface structure can be observed, so that when a high-definition liquid crystal display is incorporated, there is a possibility of occurrence of ripples or flicker. Sex. Reference Example 1 In addition to 85 parts by mass of the raw material of the light-diffusing layer (B), the crystalline homo-polyester (M1) and 15 parts by mass of polystyrene (M3) were dried under reduced pressure at 135 t for 6 hours (1 Torr). The mixture is supplied to the extruder 2, and 100 parts by mass of the raw material of the light-diffusing layer (A) is dried under reduced pressure (1 Torr) at 135 ° C for 6 hours to supply the crystalline homo-polyester (M1). The light diffusing polyester film of Reference Example 1 was produced in the same manner as in Comparative Example 2 except for the extruder 1. -62-200933202 The film properties obtained in Reference Example 1 are shown in Table 1. The film of the reference example 1 has a large number of voids inside the light-diffusing layer because the contribution of the internal haze to the total haze greatly reduces the total light transmittance, and it is considered that the brightness is greatly reduced when incorporated into the liquid crystal display. Reference Example 2 24 parts by mass of the raw material of the light-diffusing layer (B) was dried under reduced pressure at 135 ° C for 6 hours (1 Torr), and the crystalline homopolymer (M1) and 66 parts by mass were reduced at 70 ° C. The copolymerized polyester (M2) and 10 parts by mass of polystyrene (M3) after pressure drying for 12 hours (1 Torr) were mixed and supplied to the extruder 2. Further, 1 part by mass of the raw material of the light-diffusing layer (A) was supplied to the extruder 1 after the crystalline homopolymer (M1) was dried under reduced pressure (1 Torr) at 135 ° C for 6 hours. The gears of the respective extruders were controlled in such a manner that the thickness ratio of the (A) layer and the (B) layer was 90 to 10. The pulling speed of the unstretched film was adjusted by cooling the drum in such a manner that the stretched film thickness was 25 μm. When the unstretched film was longitudinally stretched in the flow direction, the heating temperature by the preheating roll was 75 ° C and the longitudinal stretching was 3.3 times between the rolls of different peripheral speeds. At this time, the temperature of the near-infrared heater is controlled so that the maximum temperature of the film in the stretching section is 9 (TC). @ Both ends of the biaxially stretched film coated with the coating layer are gripped by a clip and guided to the expansion. After preheating at 90 ° C, it was stretched 2.5 times in the width direction at 95 ° C, then stretched 1.6 times in the width direction at 95 ° C, further heat treated at 223 ° C for 22 seconds, and cooled to 60 °. The process of C was subjected to a relaxation treatment of 1.3% in the width direction. A surface light diffusing polyester film having a total thickness of 25 μm was prepared in the same manner as in Example 1 except the above. The film characteristics obtained are shown in Table 1. The film of the reference example 2 had a small surface alignment coefficient, poor dimensional stability, and a large curl. The film obtained was extremely curled and the thermal dimensional stability could not be evaluated. 200933202
【一谳】 8 • S g ο ο 直添 1 1 家 CO cn * vn Os v〇 oo r*S S cn 兩面 § : 0.07 1 Γ ΟΟ — — oo VI ο »-\ r— 〇 oo X I 班 m 璀 m 赛 m m Iv-m r 〇 r— X 8 8 • g i/~i ο 直添 I Os 8 ^3- en • § CO § - vq ° i ο c〇 cn § 2 0.17 0.56 vn S3 s m r- — v〇 : σ\ X p CO o 〇 r _ 〇 o § S cs • g W-) U ON S cn rn - § vn en § s so OO 兩面 〇〇 2Ξ 异 0.Π Γ0 0.58 oo v〇 - Ό : σν o i X sq oo IS 〇 P m 鎰二 A3 8 S8 2 g W-> - 验 倾 1 σ\ S CO P § \r\ cn f s v〇 〇·) Γ^ oq 兩面 E S s oo vn O Si 二 ε SO : σ\ s X 〇_ 〇\ is m o b m 溢2 8 gg g - 直添 σ\ 8 ro cS • § »n CO o <N »〇 oo CO L C>4 ro 兩面 L： 〇〇 t CS 1 〇 § oo m 〇 S? ： Ό t s〇 : On X ro te r- o b 8 — §8 CN g VI SO 直添 1 σ\ B fO • § u-> § Γ s v〇 r co cn L 1 l~ L ΓΟ 兩面 g Γ 1 0,09 Γ： 对 0.58 5 S R r〇 h r~> L 〇\ JQ 00 X ΓΛ oo o cn L o 〇 8 L 二 g 卜 L SO 直添 1 L 8 m CO ' [ W1 cn § s 卜 oo I 卜 L cn 兩面 g 卜 0.10 卜 CN oo w-* o 〇 h \o : On X <N f·^ oo h !- L 〇 〇 溢卜 § g o — g r- 兮 直添 1 S CO § u-i m § s NO oo cn I cn· -1 § 〇 0.14 〇〇 OO 0.57 7 ΓΊ Γ- ; X 1 〇\ o i_ § S 〇 〇 湓〇 § Si 卜 g 2 ο 直添 § 8 cn CO § xn cn § v〇 ΰ〇 cn s tr\ 兩面 «λ CS 0.15 <s 0.57 冢 CO T : 闵 X ；m i〇 1 s Γ S 〇 o' 1 Β _ g s • g 2 对 直添 § 8 cn ' § υ-> co f s NO 寅 PO 1 § 〇 - 0.14 OO 2 5； : r- i民 l· o 0 1 Is Ol p i P 鎰呀 S； S • 2 - ο 直添 § ΟΝ 8 5 - § o <j 5' s 2 C*1 ro 兩面 8 〇 0.12 β v 0.57 冢 ο Γ- r~ iS ί X 1° g i〇 〇 «» ' wn 2 ο 1 I Ον 8 S • — Wi CO § vq 〇 <N o m rn ， Β 〇 0.09 S 勺 __058 - 实 oo t^l μ S3 X rn Γ-; g g 〇 0 湓〜 丑莓 汉 r- 汉 P- - g l/"» ο 直添 § 8 ^r cn • § m on f W~1 vq O I o m cn 8 〇 0.12 K C-l CN V O c ο Γ- r- S X Γ- c> (N W\ -\ § 〇 〇 鎰― 8 * o g Ο 异 m 樾 Ρ § § s § s <〇 o 1 o cn 兩面 8 〇 oo 芄 oo o 2 C〇 V» X S| j g! g 〇 0 闺二 W萃 8 S - • g Γ- m 1 氏 8 § m cn § s vq oo cn I 匚 CO C»S 兩面 § 0.09 I CN 0.58 cn 叫 ί o -.1 §! §' 多 〇j o 留茂 WM 8 - • g r- 二 CQ § α. § cn • § c〇 o s >〇 oo cn 汉 rs 3 兩面 § 3 cs 0.58 IQ s m oo J 冢丨 Ί d r-· 1 〇\! W-l si d 〇 闺二 mm _ 8 Ί — S 一 , g 〕 Γ1 _I m ΟΝ Π 8 Ί S § Wi c*- § _J 5 3 «j ; CO -J 1 —J 3 1 兩面 〇0 R 3 C § __| iN Π O a 〇〇 m 寸 -1 v〇 S -1 Π 〇 CO -1 CO OJ 〇 〇 闺ϋ 8«匡 S 卜 1 Si J Ί r~* J • g 1 ο m 1 〇\ § 呀 rn 1 J § »/*i c*· f l〇 oi vq <q Ί § o cn 8 1 〇 0.12 VO S Ό 0.55 荨 _1 a ο Wi P- S 〇 o 〇\ § § 〇 〇 闺二 W莩 8 J g O • 2 ο Π m 1 8 s § w-> f** o W~1 r4 v〇 o s o C<"> cn 兩面 § s〇 C； s \C 0.54 m v〇 S5 Ρΐ 〇 o OO o § o 0 〇 ω W « 〇 w 跳 § w H o 受: W « X 駿 _ δ m 戚 m 4〇 靥Β的厚度比率(％) 添加劑的添加方法 1 _ 6 m 疾 m m ί m f： 黎 g 0 接 m /**« μ _ i; g 轉 i: i S9 f： s § ffi- g i 刮 i 疾 g i m 囲 m m g m 毅 塗布液(M4)的塗布 薄融厚度(微米） * 接 m 进 CQ m 〇, < 1 § 3 m 拔 w E S PQ m 溢 m m Μ 趣 狭 i 另， m p 如， gp Is g 岛 1 m M m m M 嫌 m 嫌 m 屮 m m l «1 § Q tn 表面結構凹凸不均 m m m m 症 K~ m 醚 ® w 1 HlP pin 1) 嘛 1 m 岛 }] 嘛 P m m \K 1 m t 駐 1! Φ i雰 1« 1 横向 ins 兹 m CQ 幽 越 < 幽 :g :S ! 避 联 層A 光擴散 層(Β) 驾 1 i n l· 一 ii 耐熱性 國 tt m :您 寸9 200933202 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利用作爲背光板 模組、照明裝置等所使用的光擴散薄膜。又，能夠使用作 爲稜鏡薄片用基材薄膜。因此對產業界具有卓越的貢獻。 【圖式簡單說明】 第1圖係實施例1的表面光擴散性聚酯薄膜的配光不 均觀察影像。 胃2圖係比較例1的表面光擴散性聚酯薄膜的配光不 u 均觀察影像。 【主要元件符號說明】 無。 〇 -65-[一谳] 8 • S g ο ο Add 1 1 CO cn * vn Os v〇oo r*SS cn Both sides § : 0.07 1 Γ ΟΟ — — oo VI ο »-\ r — 〇oo XI 班 m 璀m Race mm Iv-m r 〇r— X 8 8 • gi/~i ο Add I Os 8 ^3- en • § CO § - vq ° i ο c〇cn § 2 0.17 0.56 vn S3 sm r- — V〇: σ\ X p CO o 〇r _ 〇o § S cs • g W-) U ON S cn rn - § vn en § s so OO two sides 〇〇 2 Ξ different 0. Π Γ 0 0.58 oo v〇- Ό : σν oi X sq oo IS 〇P m 镒二A3 8 S8 2 g W-> - Check 1 σ\ S CO P § \r\ cn fsv〇〇·) Γ^ oq Both sides ES s oo vn O Si Two ε SO : σ\ s X 〇 _ 〇 \ is mobm overflow 2 8 gg g - add σ\ 8 ro cS • § »n CO o <N »〇oo CO L C>4 ro Both sides L: 〇〇 t CS 1 〇§ oo m 〇S? : Ό ts〇: On X ro te r- ob 8 — §8 CN g VI SO Add 1 σ\ B fO • § u-> § Γ sv〇r co cn L 1 l~ L ΓΟ Both sides g Γ 1 0,09 Γ: to 0.58 5 SR r〇hr~> L 〇\ JQ 00 X ΓΛ oo o cn L o 〇8 L II g 卜 L SO directly add 1 L 8 m CO ' [ W1 cn § s oo I 卜 L cn two sides g 卜 0.10 卜 CN oo w-* o 〇h \o : On X <N f·^ oo h ! - L 〇〇 卜 § go — g r- 兮 添 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 S 〇〇湓〇§ Si 卜 g 2 ο 直 § 8 cn CO § xn cn § v〇ΰ〇cn s tr\ two sides «λ CS 0.15 <s 0.57 冢CO T : 闵X ;mi〇1 s Γ S 〇o' 1 Β _ gs • g 2 pairs directly § 8 cn ' § υ-> co fs NO 寅PO 1 § 〇- 0.14 OO 2 5; : r- i people l· o 0 1 Is Ol pi P 镒 S S; S • 2 - ο Add § ΟΝ 8 5 - § o <j 5' s 2 C*1 ro Both sides 8 〇 0.12 β v 0.57 冢ο Γ- r~ iS ί X 1° gi〇 〇«» ' wn 2 ο 1 I Ον 8 S • — Wi CO § vq 〇<N om rn , Β 〇 0.09 S scoop __058 - real oo t^l μ S3 X rn Γ-; gg 〇0 湓~丑莓汉r-汉 P- - gl/"» ο 直 § 8 ^r cn • § m on f W~1 vq OI om cn 8 〇0.12 K Cl CN VO c ο Γ- r- SX Γ- c> (NW\ -\ § 〇〇镒 ― 8 * og Ο m 樾Ρ § § s § s <〇o 1 o cn Both sides 8 〇oo 芄oo o 2 C〇V» XS| jg! g 〇0 闺二W extraction 8 S - • g Γ- m 1 8 § m cn § s vq oo cn I 匚CO C»S Both sides § 0.09 I CN 0.58 cn ί ί o -.1 §! §' 多〇jo 留茂 WM 8 - • g r- 二 CQ § α. § cn • § c〇os >〇oo cn Han rs 3 two sides § 3 cs 0.58 IQ sm oo J 冢丨Ί d r-· 1 〇\! Wl si d 〇闺 two mm _ 8 Ί — S one, g 〕 Γ1 _I m ΟΝ Π 8 Ί S § Wi c*- § _J 5 3 «j ; CO -J 1 — J 3 1 Two-sided 〇0 R 3 C § __| iN Π O a 〇〇m inch-1 v〇S -1 Π -CO -1 CO OJ 〇〇闺ϋ 8«匡S 卜 1 Si J Ί r~* J • g 1 ο m 1 〇\ § 呀rn 1 J § »/*ic*· fl〇oi vq <q Ί § o cn 8 1 〇0.12 VO S Ό 0.55 荨_1 a ο Wi P- S 〇 o 〇 § § 〇〇闺 莩 W莩8 J g O • 2 ο Π m 1 8 s § w-> f** o W~1 r4 v〇oso C<"> cn Both sides § s〇 C; s \C 0.54 mv〇S5 Ρΐ 〇o OO o § o 0 〇ω W « 〇w 跳 § w H o Subject to: W « X Jun _ δ m 戚m 4〇靥Β Thickness ratio (%) Addition of additives 1 _ 6 m 疾mm ί mf: 黎g 0 接m /**« μ _ i; g to i: i S9 f: s § ffi- gi shaving i disease gim 囲mmgm yi coating liquid (M4) coating thin melt thickness ( Micron) * Connect m into CQ m 〇, < 1 § 3 m pull w ES PQ m overflow mm Μ interesting narrow i, mp eg, gp Is g island 1 m M mm M m m m m 屮mml «1 § Q tn Surface structure unevenness mmmm Symptom K~ m Ether® w 1 HlP pin 1) Well 1 m Island}] Well P mm \K 1 mt Station 1! Φ i atmosphere 1« 1 Horizontal ins 兹 m CQ 幽越< ; 幽:g :S ! Avoiding the layer A light diffusing layer (Β) Driving 1 inl · ii Heat resistant country tt m : You inch 9 200933202 Industrial use possibility The surface light diffusing polyester film of the present invention can be utilized A light diffusing film used as a backlight module, a lighting device, or the like. Further, a base film for a bismuth sheet can be used. Therefore, it has made outstanding contributions to the industry. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing an uneven light distribution of a surface light diffusing polyester film of Example 1. In the stomach 2, the light distribution of the surface light diffusing polyester film of Comparative Example 1 was observed. [Main component symbol description] None. 〇 -65-