201142367 六、發明說明： 【發明所屬之技術領域】 本發明是關於一種兼具隱蔽性與光利用效率，同時提 供剛性之LED照明用光擴散薄膜。 【先前技術】 基於近年來技術成長與能量消耗之效率化的背景， LED開始進入照明的領域。就其與迄今的照明之白熾燈 泡、螢光燈大相逕庭的點而言，可列舉LED爲點光源。因 此，將LED利用作爲照明的情況，係謀求隱蔽性大，且光 的利用效率高之光擴散薄膜（例如，參照日本特開2009-32563號公報）以消除點光源的燈管影像。然而，一般而言 隱蔽性增大時，效率會大幅減少，因而隱蔽性與光利用效 率之兼備係爲困難。 又，當利用於照明時，爲了防止掉落，必須有不因風 壓或按壓而撓曲的程度之剛性。然而，通常貼合複數張光 擴散薄片以賦予剛性時，會因貼合部的反射而減少光效率。 就光擴散薄片的實例而言，例如，已揭示在背面投射 之透射型螢幕中（其係能夠從投影器之反對側隔著螢幕觀 看從投影器所投影的映像），具有含透明黏結劑、與平均粒 徑爲1.0〜10// m且相對於前述透明黏結劑的折射率之相對 折射率η爲0.91<n<1.09(惟n#l)的球狀微粒子的前方散射 性光散射層，且影像鮮明度爲60.0%以上（例如，參照日本 專利第3993980號說明書。）。在此透射型螢幕是揭示如下 形態：具備使所入射的光對於進行方向幾乎完.全散射至前 201142367 方，而不會往後方散射之前方散射性之光散射層，此光散 射層是與黏著層一起被夾持在2個透明體之間。 又，有揭示一種光擴散薄片，在用於液晶顯示裝置之 背光單元的光擴散薄片中，在透明薄膜的表面上，形成在 於透光性樹脂分散有微粒子群而成的光擴散層，在該光擴 散層上形成有在透光性樹脂埋設微粒子群而成的集光層之 光擴散薄片，其中構成該光擴散層之透光性樹脂與微粒子 群的折射率差之絕對値爲0.05以上，而且該集光層之表面 粗糙度以算術平均粗糙度計爲0.5 w m以上且7 ^ m以下（例 如，參照日本特開2007-23 3343號公報。）。 【發明內容】 發明欲解決之課題 有鑑於上述課題，本發明之課題爲提供一種兼具高隱 蔽性與光利用效率之光擴散薄膜。 解決課題之手段 經由本發明者等之鑽硏探討，發現藉由使用含有粒子 之內部散射層與表面形狀層的2層，在貼合基板時的內側 設置內部散射層，而且在基板外側提供表面形狀層，且設 在內側之內部散射層含有平均粒徑A爲特定的範圍內之粒 子，藉此能夠成爲一種隱蔽性大、光利用效率之減低少且 具有剛性的L E D照明用光擴散薄膜。 亦即，本發明爲如下所示。 <1> —種LED照明用光擴散薄膜’其係至少具有2片基板、 201142367 在前述2片基板之間，至少含平均粒徑a爲滿足下式 (1)的粒子及黏結劑之內部散射層、與 設在一前述基板之外側表面設置之至少含粒子與黏結 劑之表面形狀層。 式（1) 0.5emSAS5.0/zm <2>如前述<1>記載之LED照明用光擴散薄膜，其中相對 於100質量份之前述黏結劑，前述內部散射層中的粒子的 含量爲10質量份~120質量份。 <3>如<1>或<2>中任一項所記載之LED照明用光擴散薄 膜，其中前述內部散射層中的粒子係具有交聯結構之有機 粒子。 <4>如<1>~<3>中任一項所記載之LED照明用光擴散薄 膜，其中前述內部散射層係含有交聯劑。 <5>如<1>〜<4>中任一項所記載之LED照明用光擴散薄 膜，其中前述內部散射層之黏結劑的折射率爲1.40以上且 1 . 7 0以下。 <6>如<1>~<5>中任一項所記載之LED照明用光擴散薄 膜，其係進一步具有黏著層。 <7>如<6>所記載之LED照明用光擴散薄膜，其中相對於 前述所鄰接的基板的折射率N 1與前述黏著層的折射率 N2，前述內部散射層的平均折射率N3係滿足下式（2)。 式（2) N2<N3 S N1 <8>如<1>〜<7>中任一項所記載之LED照明用光擴散薄 201142367 膜，其中在未設置前述表面形狀層之基板的外側表面，具 備具有比前述基板的折射率更低之折射率的層。 <9> 如<1>〜<8>中任一項所記載之LED照明用光擴散薄 膜，其中在前述表面形狀層的表面具備具有比該表面形狀 層所含有之粒子的折射率更低的折射率之層。 <1〇>如<1>〜<9>中任一項所記載之LED照明用光擴散薄 膜，其中內部散射層中的黏結劑及前述表面形狀層中的黏 結劑係含有選自水溶性高分子及水分散性高分子之至少1 種。 <11>如<1>~<10>中任一項所記載之LED照明用光擴散薄 膜，其中前述基板之至少一者爲PET薄膜。 <12>如<1>〜<11>中任一項所記載之LED照明用光擴散薄 膜，其中設置前述表面形狀層的基板爲PET薄膜。 <13>如<12>中任一項所記載之LED照明用光擴散薄膜， 其中未設置前述表面形狀層的基板是由折射率比PET薄膜 低的材料所構成。 <14>如<13>中任一項所記載之LED照明用光擴散薄膜， 其係鄰接前述PET薄膜而設置內部散射層。 <15>如<11>〜<14>中任一項所記載之LED照明用光擴散薄 膜，其中前述PET薄膜爲雙軸延伸的薄膜。 發明效果 根據本發明，即使貼合2片以上基板以賦予剛性時， 也能夠提供隱蔽性大、容易消除LED燈管影像、且可抑制 201142367 光利用效率之減低的光擴散薄膜。 【實施方式】 實施發明之形態 本發明之LED照明用光擴散薄膜（以下有時簡稱爲r光 擴散薄膜」）具有至少2片基板、在前述2片基板之間，至 少含平均粒徑A爲滿足下式（1)的粒子及黏結劑之內部散射 層、與設在一前述基板之外側表面之至少含粒子與黏結劑 之表面形狀層。 式（1) 0.5^ 5.0// m 在本發明之LED照明用光擴散薄膜中，雖然不清楚隱 蔽性大、且可抑制光利用效率之減低的理由，但可推測爲 如以下所說明。 推測貼合2片以上基板時，此基板之貼合內側設置含 有具上述特定平均粒徑之粒子的內部散射層，藉此利用該 內部散射層的存在而抑制在貼合部之界面的反射，進而在 基板的外側表面具備含有粒子之表面形狀層，藉以提高隱 蔽性且提高光利用效率。 又’內部散射層中之黏結劑具有黏著性，內部散射層 係亦可兼具黏著層之機能，亦可爲設置內部散射層與另外 設置黏著層之形態。 本發明之光擴散薄膜視需要亦可進一步具有背層等之 其他層。在第1圖··第4圖顯示本發明之LED照明用光擴散 薄膜的一實例之示意截面圖。又，在第1圖〜第4圖顯示設 201142367 置內部散射.層與另外設置黏著劑層之形態。 第1圖所示的光擴散薄膜具有2片基板10,12 ’在該2 片基板10,12分別相接設置內部散射層14,16。再者，該2 層內部散射層14,16之間是以黏著層18黏著。又’在一基 板12中，在與設有內部散射層16的面之相反面上’設置 表面形狀層20/ 第2圖所示的LED照明用光擴散薄膜係具有2片基板 10,12，由基板10起依序設置黏著層18、內部散射層16、 基板12。再者，在基板12中，在與設有內部散射層16的 面之相反面上，設置表面形狀層20。 第3圖所示之LED照明用光擴散薄膜係具有2片基板 10,12，由基板10起依序設置內部散射層16、黏著層18、 基板12。再者，在基板12中，在與設有黏著層18的面之 相反面上，設置表面形狀層20。。 第4圖所示之LED照明用光擴散薄膜是在第1圖所示 的LED照明用光擴散薄膜中進一步在最表面設置低折射率 層22。又，第4圖是圖示在第1圖的LED照明用光擴散薄 膜設有低折射率層22之結構，但當然第2圖或第3圖之 LED照明用光擴散薄膜亦可爲設有低折射率層22之結構。 又，在第4圖’係在最外層之表面形狀層20的表面與基板 10的表面兩者設有低折射率層22，亦可僅在一方設置。 在本發明之LED照明用光擴散薄膜中，更佳的層結構 爲如第1圖所示，在基板1 0，1 2之間設置內部散射層丨6之 201142367 形態。藉由成爲此種層結構，基板10，12的折射率差係以 內部散射層1 6加以緩和，有效地抑制在界面之反射而提升 了光利用效率。尤其是設置黏著層18時，由於黏著層18 的折射率大多與基板1 〇，1 2的折射率相異，因此設置本發 明的內部散射層是有意義的。 以下詳細說明構成本發明之LED照明用光擴散薄膜的 構件。 <基板> 就基板而言，只要爲透明且具有一定程度的強度之薄 片’則無特別限制，可依照目的適宜選擇使用作爲通常基 板所使用之塑膠或玻璃，特佳爲塑膠》 就前述塑膠而言，可適合列舉例如聚酯、聚烯烴等。就 前述聚酯而言，可列舉例如聚對酞酸乙二酯（PET、折射率 1.67)、聚萘二甲酸乙二酯（PEN)等。就其他塑膠而言，可列舉 例如聚醯胺 '聚醚、聚苯乙烯、聚酯醯胺、聚碳酸酯、聚苯 硫醚、聚醚酯、聚氯乙烯、聚丙烯酸酯、聚甲基丙烯酸酯等。 此等之中，較佳爲聚酯樹脂，更佳爲基板之至少1者 爲以聚對酞酸乙二酯（PET)所構成者。 作爲基板所用之聚對酞酸乙二酯（PET)較佳是將聚酯 樹脂熔融擠出爲薄膜狀，在縱向及橫向進行雙軸延伸而成 形者。藉由雙軸延伸而配向結晶化且提升強度·耐熱性，因 此變得適合作爲LED照明用光擴散薄膜之基板使用。 延伸倍率係無特別限制，但以在縱橫方向分別延伸 201142367 β ' 佳 較 爲 倍 圍 方 範 的 述 知 上 周 爲 用 率。使 倍度擇 伸厚選 延的宜 。勻適 右均可 左及件 倍、條 度及 ?強法 爲械方 佳機造 的製 分之 充膜 得薄。 可等件 ’ 此 條 時 及 內 法 又，使基板爲聚對酞酸乙二酯，另一基板爲其他塑膠 時，較佳爲將設置表面形狀層的基板以聚對酞酸乙二酯構 成，靠近照明器具側的基板以其他塑膠構成。就靠進照明 器具側之基板所用的其他塑膠而言，以使用折射率比聚對 酞酸乙二酯（PET)更低的材料爲較佳，例如，較佳爲應用聚 碳酸酯（折射率1.58)、聚甲基丙烯酸甲酯（折射率1.50)等丙 嫌酸樹脂等。 又，將設置表面形狀層的基板12設爲聚對酞酸乙二酯 (PET)、靠近照明器具側的基板1〇設爲其他塑膠時，如第1 圖、第2圖所示，鄰接著PET薄膜基板12設置內部散射層 16能夠緩和PET薄膜基板12與黏著層18之折射率差，且 抑制在界面之反射等，就提高光利用效率的觀點而言爲較 合適。 基板的厚度只要是作爲基板通常採用的範圍之厚度則 無特別限制’可依照目的加以適宜選擇，例如，以 0.02mm〜4.0mm爲較佳。 在前述基板之表面，爲提升與內部散射層或表面形狀 層的密合性，亦可進行放電處理。 <內部散射層> -10- 201142367 就內部散射層而言，爲了發揮光擴散機能’而#胃粒 子及黏結劑。此粒子的平均粒徑A係滿足下式（1) ° 式（1) 0.5/z 5.0^ m 當設計光擴散薄膜使其成爲與用以消除燈管影像之隱 蔽率大致相同時，在內部散射層所含的粒子的平均粒徑A 爲小於0.5 a m的情況下，散射機能降低或後方散射增加而 使光利用效率顯著降低，在超過5.0 // m的情況下光利用效 率亦爲降低。 以下詳細說明內部散射層所含成分。 (粒子） 內部散射層所含有的粒子是如前所述，平均粒徑A爲 滿足前述式（1)，更佳爲平均粒徑A在l#m以上以下 的範圍內。 就粒子的材質而言係沒有特別限制，可依照目的加以 適宜選擇，可適當列舉例如聚甲基丙烯酸甲酯樹脂粒子、 三聚氰胺樹脂粒子、聚苯乙烯樹脂粒子、聚矽氧樹脂粒子 等之有機粒子。此等可1種單獨使用，亦可組合使用2種 以上。 前述有機粒子以具有交聯結構者爲較佳。又，有機粒 子亦可爲經被覆表面者，例如可適合使用以矽石等被覆、 依照塗布液種類將表面予以親水化或疏水化處理之粒子。 就前述粒子的添加量而言，相對於1 00質量份之下述 黏結劑，前述粒子的添加量以1 〇~ 1 20質量份爲較佳。粒子 -11 - 201142367 的添加量若在上述範圍內時，則在黏結劑中的粒子分散性 變得良好，可充分發揮作爲光擴散劑的機能。相對於100 質量份之黏結劑，粒子的添加量更佳爲1 0〜1 1 〇質量份、進 一步更佳爲10~105質量份。 (黏結劑） 在本發明，黏結劑係指在內部散射層中除了上述粒子 之全部固體成分（包括後述之超微粒子）。具體而言，包括 樹脂、超微粒子、其他添加劑等。 具體而言，黏結劑的折射率較佳爲1.4 〇以上且1.7 0以 下、以1.40以上且1.60以下爲更佳。 -樹脂- 作爲黏結劑所含的樹脂，例如，在用水當作內部散射 層塗布液之分散媒的情況下，宜使用選自水溶性高分子及 水分散性高分子之至少1種樹脂。就黏結劑樹脂而言，適 合列舉單獨聚合物或共聚物等。 就前述單獨聚合物或共聚物而言，可列舉例如（甲基） 丙嫌酸樹脂、醋酸乙烯酯樹脂、乙烯-醋酸乙烯酯共聚樹 脂、氯乙燒樹脂、氯乙烯-偏二氯乙烯共聚樹脂、縮丁醛樹 脂、聚矽氧樹脂、聚酯樹脂、偏二氟乙烯樹脂 '硝基纖維 素樹脂、苯乙烯樹脂、苯乙烯-丙烯腈共聚樹脂、聚胺基甲 酸酯樹脂、聚乙烯、聚丙烯、氯化聚乙烯、松香衍生物等。 水彳谷性及/或水分散性高分子係無特別限定，可依照目 的加以適宜選擇。 -12- 201142367 可列舉例如聚乙烯醇、甲基纖維素、明膠、聚酯樹脂 系、聚胺基甲酸酯樹脂系、丙烯酸樹脂系、胺基樹脂系、 環氧樹脂系、苯乙烯丁二烯共聚物系等之水溶性或水分散 性高分子’其中以丙烯酸樹脂系、聚酯樹脂系、聚胺基甲 酸酯樹脂系之水分散高分子爲較佳。此等可單獨使用1 種，亦可組合使用2種以上。 又’以使用可與交聯劑反應之高分子爲較佳。例如， 可使用具有羥基、胺基、羧基等之高分子。進一步地，水 分散性高分子以含有例如磺酸基、羥基、羧酸基、胺基、 醯胺基、醚基等取代基等爲較佳。又，此等水分散性高分 子係可單獨使用，亦可混合使用。 又在兼具作爲黏著層之機能的情況下，亦可使用在 下述黏著層所說明的樹脂作爲內部散射層之樹脂。 再者’爲了提供處理時的耐傷性、對於用以擦拭附著 在表面的灰塵或髒污的溶劑之耐溶劑性、及將此led照明 用光擴散薄膜沖壓加工成預定形態時與基板之密合性，較 佳爲在內部散射層添加用以使其硬膜之交聯劑。 -其他添加劑- 再者，爲了提供處理時的耐傷性、對於用以擦拭附著 在表面的灰塵或髒污的溶劑之耐溶劑性、及將此led照明 用光擴散薄膜沖壓加工成預定形態時與基板之密合性，較 佳爲在內部散射層添加用以使其硬膜之交聯劑。 -交聯劑- -13- 201142367 就前述交聯劑而言，以碳二醯亞胺化合物、異氰酸酯 化合物爲較佳'碳二醯亞胺化合物爲更佳。 使用於本發明之碳二醯亞胺化合物是在分子內具有碳 二醢亞胺基’例如藉由與聚酯樹脂之羧基的反應，形成胺 甲醯基醯胺鍵、或藉由與聚酯樹脂的羥基之反應形成異脲 鍵等化學結構。又，就該化學結構而言，亦包含在與胺基 反應時所生成的狐結構。 就一般市售品而言，可使用日清紡的Carbodilite E系 列（乳液型）、V系列（水性型）等。 就前述異氰酸酯化合物而言，可使用在分子內具有至 少2個、較佳爲具有3個以上之官能基的脂肪族異氰酸酯 化合物、環狀脂肪族異氰酸酯化合物、及芳香族多官能異 氰酸酯化合物之至少任一者。關於異氰酸酯化合物，係記 載於「聚胺基甲酸酯樹脂手冊」（岩田敬治編、日刊工業新 聞社發行、1 987年）。 此等交聯劑可單獨或混合2種以上使用。 -超微粒子- 再者，在前述內部散射層亦可添加例如由無機粒子構 成的超微粒子等作爲其他粒子。前述超微粒子可提高塗布 適性、控制黏結劑之折射率。 前述超微粒子係沒有特別限制，可依照目的適宜選擇 通常使用的物質使其分散。例如，可列舉矽石、碳酸鈣、 氧化鋁、氧化锆、氧化鈦等。 -14- 201142367 超微粒子之粒徑以在0.005em~0.150/zm的範圍爲較 佳、在0.005/zm〜0.100//m的範圍爲更佳。 前述超微粒子在前述內部散射層中的添加量係沒有特 別限制，可依照狀況加以適宜遵擇，惟，以例如丨~20質量 %爲較佳。 -溶劑- 就前述內部散射層塗布液中所使用的溶劑係沒有特別 限制，可由水或有機溶劑等通常使用者之中加以適宜選擇 使用。 就前述有機溶劑而言，可列舉例如酮類、醚類、醇類、 酯類、多元醇衍生物類、羧酸類等。 前述內部散射層是在黏著層上塗布前述內部散射層塗 布液後，進行乾燥所形成。前述內部散射層可僅設置1層， 亦可設置2層以上。 前述內部散射層塗布液之塗布方法係沒有特別限制， 可依照目的加以適宜選擇，可以例如旋轉塗布機、滾筒塗 布機、棒狀塗布機、簾幕塗布機等通常使用的塗布手段來 進行。 就前述內部散射層塗布液之乾燥方法而言係沒有特別 限制，可依照所使用之溶劑的種類適宜選擇通常使用的方 法。例如，用水作爲溶劑時，從短時間而且不對材質造成 損傷的方面而言，乾燥溫度以90°C〜140°C爲較佳、10(TC ~1 40 °C爲更佳。在前述範圍內之乾燥溫度係不需要長時間 -15- 201142367 乾燥，且可抑制對材質之損傷。就前述乾燥時間而言，例 如以10秒鐘〜5分鐘爲較佳、1分〜3分鐘爲更佳。 (物性値等） 從達成光散射·效率之效果的觀點而言，內部散射層的 厚度以l；am〜20/zm爲較佳。 相對於前述基板的折射率N1與後述黏著層的折射率 N2，內部散射層的平均折射率N3較佳爲滿足下式（2)。 式（2) N2<N3 ^ N 1 在此’平均折射率N3是將黏結劑（粒子以外的固體成 分）的各自折射率當作Ni，將各黏結劑所含固體成分的體積 比例當作Vi時，以Σ Ni* Vi所計算出的値。 藉由滿足式（2)，內部散射層的折射率N3會成爲黏著 層的折射率N 2與基板的折射率N 1中間的値。藉由具有此 種折射率之內部散射層的存在，黏著層與基板的折射率差 受到緩和’有效抑制在界面之反射，而使光利用效率提升。 具體而言’內部散射層的折射率N3以1.50〜1.67爲較 佳、1.50〜1.60爲更佳。 5^ ’從抑制基板與內部散射層之在界面的反射而提高 光利用效率的觀點而言，基板的折射率N1與內部散射層的 折射率N3的差以〇〜ο.〗爲較佳。 胃# ’《έ抑制黏著層與內部散射層之在界面的反射而 提高光利用效率的觀點而言，後述黏著層的折射率Ν2與內 部散射層的折射率Ν3的差以〇〜〇.1爲較佳。 -16- 201142367 <黏著層> 如前所述通，前述內部散射層兼具黏著層之機能時， 黏著層之設置則非爲必須，但在設置黏著層的情況下，可 用以下成分構成。 就前述黏著層，可爲丙烯酸系、胺基甲酸酯系、環氧 基系、聚矽氧系等，沒有特別限制，可依照目的適宜選擇 使用通常所使用之物質。具體而言，就積層系之市售品而 言，可列舉例如對東洋油墨公司製的LIS805之胺基甲酸醋 系主劑添加LCR-901之異氰酸酯系硬化劑而可使用的2液 系之乾式積層材料。再者，就積層而言，亦可適宜利用適 合擠出方式、熱熔融方式之材料。 黏著層的折射率N2較佳爲滿足前述式（2)，具體而言， 以1.5〜1.67爲較佳。 從無損光透過性且確實黏著之觀點而言，黏著層的厚 度以lvm~50/zm爲較佳、lym〜2//m爲更佳。 <表面形狀層> 表面形狀層係至少含粒子及黏結劑。 (黏結劑） 就表面形狀層所含有的黏結劑而言，可應用與在內％ 散射層所說明的黏結劑相同之物。 (粒子） 就表面形狀層所含有之粒子的材質而言，係沒有特別 限制，可依照目的加以適宜選擇’可適合列舉例如聚甲基 -17- 201142367 丙烯酸甲酯樹脂粒子、三聚氰胺樹脂粒子、聚苯乙烯樹脂 粒子、聚矽氧樹脂粒子等有機粒子。此等係可1種單獨使 用，亦可組合使用2種以上。 表面形狀層所含有之粒子的平均粒徑B以在0.5# m以 上且50/zm以下之範圍內爲較佳、以3/zm以上20#ιη以 下的範圍內爲更佳。 又，表面形狀層所含有之粒子的平均粒徑Β是比內部 散射層所含.有之粒子的平均粒徑Α更大，此點由在白色 LED光源中色調的變化減少之觀點而言爲較佳。具體而 言，平均粒徑B以比平均粒徑A大1 # m以上爲較佳、以 大3ym以上爲更佳。 就前述粒子的添加量而言，相對於100質量份之前述 黏結劑樹脂，以5質量份~400質量份爲較佳、50質量份〜3 00 質量份爲更佳。粒子的添加量若在上述範圍內，則黏結劑 中的粒子分散性變得良好，可充分發揮作爲光擴散劑之機 能。 (其他添加劑） 與內部散射層同樣地，在表面形狀層中亦可進一步添 加交聯劑、超微粒子、溶劑等。在表面形狀層所添加的交 聯劑、超微粒子、及溶劑的種類是與在內部散射層所說明 的交聯劑、（超微粒子）、及溶劑各自相同。 前述超微粒子在前述表面形狀層中的添加量係沒有特 別限制，爲如上述般獲得所期望的總光線透射率及半値 -18 - 201142367 角，可依照狀況加以適宜選擇，例如，以1〜20質量％爲較 佳。 前述表面形狀層可藉由與前述內部散射層同樣的方法 形成。 (物性値等） 由達成光散射效果之觀點而言，表面形狀層的厚度以 2" m〜30μ m爲較佳、2// m〜20# m爲更佳。 <低折射率層> 本發明之LED照明用光擴散薄膜亦可在最外層的表面 具備低折率層22。在此，低折射率層是指具有比相接設置 的層（例如，基板1 0或表面形狀層2 0)的折射率更低之折射 率的層。 藉由具備低折射率層22，可抑制與空氣之界面反射， 且提升光效率。 作爲最外面之設置在基板上之低折射率層的折射率較 佳爲比基板的折射率小0.1以上、小0.1 5以上爲更佳。具 體而言，設在基板上之低折射率層的折射率以1.30〜1.50爲 較佳、1.30〜1.45爲更佳。 又，作爲最外面的設在表面形狀層上之低折射率層的 折射率較佳爲比表面形狀層中所含粒子的折射率小〇. 0 1以 上、小0.05以上爲更佳、小〇.1〇以上爲進一步更佳。具體 而言，設在表面形狀層上之低折射率層的折射率以 1.30〜1.50爲較佳、1.30~1.45爲更佳。 -19- 201142367 低折射率層所用之材料，就市售品而言’可列舉ASAHI GLASS公司製之CytopCTL-107MK(折射率1,34)等之氟系材 料、或如矽石氣凝膠之多孔質膜、或含有微小中空粒子等。 低折射率層的厚度以 0.05//m~2.00vm 爲較佳、 0.05// m〜1.00/U m 爲更佳。 <LED照明用光擴散薄膜的製造方法> 本發明之LED照明用光擴散薄膜之製造方法只要是能 夠形成上述結構的LED照明用光擴散薄膜之方法則無特別 限定。以下針對LED照明用光擴散薄膜之製造方法的一實 例加以說明。 首先，在基板上塗布至少含有前述粒子及黏結劑之內 部散射層塗布液而形成內部散射層，在未設置內部散射層 側的基板表面上塗布至少含有粒子及黏結劑之表面形狀層 塗布液而形成表面形狀層。將其稱作預先準備之第一薄膜。 然後準備另外的形成有內部散射層之基板、或未設有內部 散射層之基板。將其稱爲第二薄膜。利用黏著劑黏著先行 準備之第一薄膜的內部散射層、與第二薄膜之內部散射層 或未設有內部散射層之基板。 在本發明之LED照明用光擴散薄膜設有低折射率層 時，係藉由上述黏著劑進行黏著後，浸漬於低折射率層塗 布液，或塗布後使其乾燥。 <用途〉 本發明之LED照明用光擴散薄膜藉由其優點，可適合 -20- 201142367 使用於採用LED照明之裝置。進一步地，可例示作 動電話、個人電腦用監視器、電視、液晶投影器等 液晶顯示裝置之背光單元的光擴散薄膜使用。 又，若使用本發明之LED照明用光擴散薄膜時 兼具高隱蔽性與光利用效率，因此使用其之LED照 消除燈管影像，且維持高光利用效率，並且由於剛 可謀求裝置之長使用壽命化。 在此，本說明書所稱光利用效率是指把未*** 的全光束當作1，***薄膜後的實測値（％)。雖然現 作爲單一元件已開始達成超越作爲習知螢光燈之性 安裝作爲實際的照明器具時，仍會因發熱·電流轉換 器具形狀而減少光利用效率，而有仍不及習知的高 明之螢光燈的狀況。今後，相對於利用水銀的螢光 僅在無水銀等環境層面而且在光效率等能量消耗方 優越性，對於迄今之照明也顯示極大的訴求性，因 是1 %的光利用效率之差異，在實用上也能實現極 〇 實施例 .以下說明本發明之實施例，惟本發明係不因此 例而受任何限定。又，以下說明中，只要沒有特別限 「％」是指「質量份」「質量％」。 [實施例1 ] <薄膜1 A之製作> 爲在行 所使用 ，由於 明係可 性高而 薄膜時 今LED 能，但 效率、 效率照 燈，不 面顯現 此即使 大的差 等實施 定「份j -21 - 201142367 在厚度300 μ m之PET薄膜（折射率1.67)上，利用線棒 塗布下述組成之內部散射層塗布液1，在1 3 0 °C之烤箱加熱 硬化2分鐘。 (內部散射層塗布液1之組成） •蒸餾水：80質量份 •界面活性劑（三洋化成工業（股）、Naroacty CL-95):5質 量份 ♦粒子（日產化學（股）製、Optbeads 2000M、矽石被覆三 聚氰胺粒子、平均粒徑2 μ m、折射率1.65):20 1質量份 •超微粒子分散液（日產化學工業（股）製、Snowtex C、 矽石粒子、平均粒徑0.01/z m~0.02；a m、固體成分20%):333 質量份 •水分散性高分子（聚胺基甲酸酯樹脂、DMS NeoResins Inc.製、NeoRezR-600、固體成分 33%):368 質量份 •交聯劑（日清紡（股）製、Carbodilite V-02-L2、固體成 分40%): 12質量份 剝離所得塗布膜的一部份，利用經調節適宜條件的高 低差計（Dektak Veeco公司製）測定膜厚，平均膜厚爲2 v m。 在此，膜厚是分別剝離任意3位置，分別測定基板表面與 塗布膜的高低差，求其平均値。又，在各自的測定中，在 5 00 Am的距離測定塗布膜表面，以算出具有凹凸之表面的 平均膜厚。以下，在實施例中，膜厚係以此方法所測得。 進一步地，在此PET薄膜之與塗布有內部散射層塗布 -22- 201142367 液1的面相反的表面上，用線棒塗布下述組成之表面形狀 層塗布液1，在13(TC之烤箱加熱硬化2分鐘，製得薄膜1 A。 表面形狀層之平均膜厚爲6ym。 (表面形狀層塗布液1之組成） •蒸餾水：244質量份 •界面活性劑（三洋化成工業（股）' NaroactyCL-95):5質 量份 •粒子（積水化成品工業（股）製、SBX-8、交聯聚苯乙烯 粒子、平均粒徑8 β m '折射率1.59):264質量份 •超微粒子分散液（日產化學工業（股）製、Snowtex C、 矽石粒子、平均粒徑0.01~0.02/zm、固體成分20%):238質 量份 •水分散性高分子（聚胺基甲酸酯樹脂、DMSNeoResins Inc.製、NeoRezR-600、固體成分 33%):237 質量份 •交聯劑（日清紡（股）製、Carbodilite V-02-L2、固體成 分40%):13質量份 <薄膜1B之製作> 在厚度300 // m之PET薄膜（折射率1.67)上利用線棒塗 布前述內部散射層塗布液1，在1 3 0 °C之烤箱加熱硬化2分 鐘，製得薄膜1B。所形成之內部散射層的平均膜厚爲2em。 <薄膜1之製作> 在薄膜1A的內部散射層上，利用塗布器以6/^m厚塗 布黏著劑（東洋油墨公司製、LIS 8 05/LCR-901、折射率1.50) -23- 201142367 後，利用烤箱在1 00°C乾燥5分鐘。將此黏著層貼合 1B的內部散射層後，以〇.4Mpa之壓力進行積層， 膜1。 [實施例2 ] <薄膜1D之製作> 在厚度300 μ m之PET薄膜（折射率1.67)上利用 布前述內部散射層塗布液1，在1 3 0 °C之烤箱加熱硬 鐘。所形成之內部散射層的平均膜厚爲4/zm。 進一步地，在此PET薄膜之與塗布有內部散射 液1的面相反的表面上，用線棒塗布前述表面形狀 液1，在1 30°C之烤箱加熱硬化2分鐘，製得薄膜 面形狀層之平均膜厚爲6vm。 <薄膜2之製作> 在薄膜1D的內部散射層上，利用塗布器以6# 布黏著劑（東洋油墨公司製、LIS805/LCR-901、折射】 後，利用烤箱在1 〇〇°C乾燥5分鐘。將此黏著層貼合 薄膜（折射率1.67)後’以0.4Mpa的壓力進行積層， 膜2。 [實施例3] 〈薄膜1C之製作> 在厚度300 # m之PET薄膜（折射率1.67)上利用 布前述表面形狀層塗布液1，在1 3 0 °C之烤箱加熱硬 鐘，製得薄膜1C。所形成之表面形狀層之平均膜 於薄膜 製得薄 線棒塗 化2分 層塗布 層塗布 1 D。表 m厚塗 替 1.50) 於PET 製得薄 線棒塗 化2分 厚爲、 -24- 201142367 6 v m 〇 <薄膜IE之製作> 在厚度300 y m之PET薄膜（折射率1.67)上利用線 布前述內部散射層塗布液1，在丨3〇。(：之烤箱加熱硬化 鐘’製得薄膜1E。所形成的內部散射層之平均膜厚爲6 <薄膜3之製作> 在薄膜1C中、在與表面形狀層相反的面上，利用 器以 6ym 厚塗布黏著劑（東洋油墨公司！ LIS 805/LCR-901、折射率1.50)後，利用烤箱在l〇〇°C乾 分鐘。將此黏著層貼合於薄膜1 E之內部散射層側後 0.4Mpa的壓力進行積層，製得薄膜3。 [實施例4] <薄膜4之製作> 與實施例1同樣地製作薄膜1。利用以同製品稀釋 倍稀釋 Cytop(ASAHIGLASS 公司製、CTL-107MK、折 1.34)而成的液體，旋轉塗布兩面後.，在100。(：的烤箱 30分鐘而作成低折射率層，製得薄膜4。將薄膜4的 構之示意圖示於第4圖。 [實施例5] <薄膜5之製作> 在薄膜1D的內部散射層上，利用塗布器以6/zm 布黏著劑（東洋油墨公司製、LIS 805/LCR-901、折射率 後，利用烤箱在100 °C乾燥5分鐘。將此黏著層貼合於 棒塗 2分 β m。 塗布 契、 :燥5 ，以 液4 射率 乾燥 層結 厚塗 1.50) 聚碳 -25- 201142367 酸酯（帝人化成製 Panlite L-l 225Y，折射率1.59)後，以 0.4Mpa的壓力進行積層，製得薄膜5。 [實施例6] <薄膜6之製作> 在薄膜1C中、在與表面形狀層相反的面上，利用塗布 器以6 v m厚塗布下述黏著劑1 (內部散射層）後，利用烤箱 在100 °C乾燥5分鐘。將此黏著層貼合於在厚度3 00 //m之 PET薄膜（折射率1.67)後，以0.4Mpa的壓力進行積層，製 得薄膜6。將薄膜6之層結構的示意圖示於第7圖。 黏著劑1 (內部散射層） •溶劑：MEK 415質量份 •黏著劑主劑：LIS 805 (東洋油墨製造股份有限公司製· 固體成分50%) 35 0質量份 •黏著劑硬化劑：LCR-901(東洋油墨製造股份有限公司 製·固體成分70%) 35質量份 •粒子（日產化學（股）製、Optbeads 2000M、矽石被覆三 聚氰胺粒子、平均粒徑2# m、折射率1.65 ):200質量份 [實施例7] <薄膜7之製作> 除了用下述內部散射層塗布液2代替實施例1的內部 散射層塗布液1以外，與實施例1同樣地製作薄膜7。 (內部散射層塗布液2之組成） •蒸飽水：9 7質量份 -26- 201142367 •界面活性劑（三洋化成工業（股）、Naroacty CL-95):6質 量份 •粒子（日產化學（股）製、〇ptbeads 2000M、矽石被覆三 聚氰胺粒子、平均粒徑2 // m、折射率1.65):26質量份 •超微粒子分散液（日產化學工業（股）製、Snowtex C、 矽石粒子、平均粒徑0.01" m~0.02y m、固體成分20%):408 質量份 •水分散性高分子（聚胺基甲酸酯樹脂、DMSNeoResins Inc.製、NeoRezR-600、固體成分 33%):448 質量份 •交聯劑（日清紡（股）製、Carbodilite V-02-L2、固體成 分40%):15質量份 [實施例8] 除了用下述內部散射層塗布液3代替實施例1之內部 散射層塗布液1以外，與實施例1同樣地製作，製得薄膜 8 « (內部散射層塗布液3之組成） •蒸餾水：94質量份 •界面活性劑（三洋化成工業（股）、Naroacty CL-95):6質 量份 •粒子（日產化學（股）製、〇ptbeads 500S、矽石被覆三聚 氰胺粒子、平均粒徑〇 _ 5 // m、折射率1.6 5): 5 9質量份 •超微粒子分散液（日產化學工業（股）製、Snowtex C、 矽石粒子、平均粒徑〇·〇1μ m〜0.02μ m、固體成分20%):392 -27- 201142367 質量份 •水分散性高分子（聚胺基甲酸酯樹脂、DMSNeoResins Inc.製、NeoRezR-6 00、固體成分 33%):434 質量份 •交聯劑（日清紡（股）製、Carbodilite V-02-L2、固體成 分4 0 %): 1 4質量份 [實施例9] 除了用下述內部散射層塗布液4代替實施例1的內部 散射層塗布液1並將內部散射層的厚度從2 # m改爲3 y m 以外，與實施例1同樣地製作，製得薄膜9。 (內部散射層塗布液4之組成） •蒸餾水：80質量份 •界面活性劑（三洋化成工業（股）、Naroacty CL-95):5質 量份 •粒子（日產化學（股）製、〇ptbeads 3500M、矽石被覆三 聚氰胺粒子、平均粒徑3.5 # m、折射率1.65):20 1質量份 .超微粒子分散液（日產化學工業（股）製、Snowtex C、 矽石粒子、平均粒徑0.01// m〜0.02/z m、固體成分20%):333 質量份 •水分散性高分子（聚胺基甲酸酯樹脂、DMS NeoResins Inc.製、NeoRezR-600、固體成分 33%):368 質量份 •交聯劑（日清紡（股）製、Carbodilite V-02-L2、固體成 分40%): 12質量份 [比較例1 ] -28- 201142367 <薄膜2A之製作> 在厚度3 00 # m之PET薄膜（折射率1.67)上，利用線棒 塗布下述組成之內部散射層塗布液5，在1 30°C之烤箱加熱 硬化2分鐘。所形成的內部擴散層之平均膜厚爲2/zm。 (內部散射層塗布液5 ) •蒸餾水：8 3質量份 •界面活性劑（花王Chemical(股）、DemolEP'固體成分 2 4 %): 2 4質量份 •粒子（石原產業（股）製、CR-50、氧化鈦粒子、平均粒 徑0.3 a m、折射率2.6 0): 4 8質量份. •超微粒子分散液（日產化學工業（股）製、Snowtex C、 矽石粒子、平均粒徑0·01~0.02# m、固體成分20%):395質 量份 •水分散性高分子（聚胺基甲酸酯樹脂、DMSNeoResins Inc.製、NeoRezR-600、固體成分 33%):436 質量份 •交聯劑（日清紡（股）製、Carbodilite V-02-L2、固體成 分4 0 %): 1 4質量份 進一步地，在該PET薄膜之已塗布內部散射層塗布液 5的面之相反面上，利用線棒塗布前述表面形狀層塗布液 卜並在1 30°C之烤箱加熱硬化2分鐘，製得薄膜2A。所形 成之表面形狀層之平均膜厚爲6ym。 <薄膜2B之製作> 在厚度300 a m之PET薄膜（折射率1.67)上利用線棒塗 -29- 201142367 布前述內部散射層塗布液5，在1 3 (TC之烤箱加熱硬化2分 鐘，製得薄膜2B。所形成的內部散射層之平均膜厚爲2μιη。 <比較薄膜1之製作> 在薄膜2Α的內部散射層上利用塗布器以6/zm厚塗布 黏著劑（東洋油墨公司製、LIS 805/LCR-901、折射率1.50) 後，在100°C的烤箱乾燥5分鐘》對此黏著層貼合薄膜2B 的內部散射層後，以0.4 Mp a的壓力進行積層，製得比較薄 膜1。 [比較例2] <薄膜3A之製作> 在厚度300 ;/ m之PET薄膜（折射率1.67)上，利用線棒 塗布下述組成之內部散射層塗布液6,在130°C之烤箱加熱 硬化2分鐘。所形成的內部散射層之平均膜厚爲6^m。 進一步地，在該PET薄膜之已塗布內部散射層塗布液 6的面之相反面上，利用線棒塗布前述表面形狀層塗布液 1 ’並在1 3 0 °C之烤箱加熱硬化2分鐘，製得薄膜3 A。所形 成之表面形狀層之平均膜厚爲6^111。 (內部散射層塗布液6) •蒸餾水：80質量份 •界面活性劑（二洋化成工業（股）、Naroacty CL-95):5質 量份 •粒子（日產化學（股）製、Optbeads 6500M、矽石被覆三 聚氰胺粒子、平均粒徑6.5 y m、折射率1.65):20 1質量份 -30- 201142367 •超微粒子分散液（日產化學工業（股）製、Snowtex C、 矽石粒子、平均粒徑〇.〇卜0.02# m、固體成分20%):333質 量份· •水分散性高分子（聚胺基甲酸酯樹脂、DMS NeoResins Inc.製、NeoRezR-600、固體成分 33%):368 質量份 ' .交聯劑（日清紡（股）製、Carbodilite V-02-L2、固體成 分40%): 12質量份 <薄膜3B之製作> 在厚度300 # m之PET薄膜（折射率1.67)上利用線棒塗 布前述內部散射層塗布液6,在130 °C之烤箱加熱硬化2分 鐘，製得薄膜3B。所形成之內部散射層的平均膜厚爲6μιη。 <比較薄膜2之製作> 在薄膜3A的內部散射層上利用塗布器以6vm厚塗布 黏著劑（東洋油墨公司製、LIS805/LCR-901、折射率1.50) 後，在100°C的烤箱乾燥5分鐘。對此黏著層貼合薄膜3B 之內部散射層側後，以0.4Mpa的壓力進行積層，製得比較 薄膜2。 [比較例3 ] <薄膜4A之製作> 在厚度300 // m之PET薄膜（折射率1.67)上利用線棒塗 布前述內部散射層塗布液1，在1 30t之烤箱加熱硬化2分 鐘。所形成之內部散射層的平均膜厚爲4^m。 進一步地，在經塗布內部散射層之上，利用線棒塗布 -31- 201142367 前述表面形狀層塗布液1，並在1 3(TC之烤箱加熱硬化2分 鐘’製得薄膜4A。所形成之表面形狀層與內部散射層的總 膜厚之平均爲10#m。 <比較薄膜3之製作> .在薄膜4A中，在基板之形成有表面形狀層的面之相反 面上，利用塗布器以6//m厚塗布黏著劑（東洋油墨公司 製、LIS805/LCR-901、折射率1.50)後，在l〇〇°C的烤箱乾 燥5分鐘。對此黏著層貼合PET薄膜（折射率1.67)後，以 0.4Mpa的壓力進行積層，製得比較薄膜3。 將比較薄膜3之層結構的示意圖示於第5圖。 [比較例4 ] <比較薄膜4之製作> 在前述薄膜1E的內部散射層上，利用塗布器以6//m 厚塗布黏著劑（東洋油墨公司製、LIS805/LCR-901、折射率 1.50)後，在l〇〇°C的烤箱乾燥5分鐘。對此黏著層貼合薄 膜1E之內部散射層後，以0_4Mpa的壓力進行積層，製得 比較薄膜4。 · 將比較薄膜4之層結構的示意圖示於第6圖。 [比較例5 ] <比較薄膜5,之製作> 與日本專利第3 9939800號說明書的實施例1同樣地進 行，製作比較薄膜5。 [比較例6] -32- 201142367 - <比較薄膜6之製作> 將曰本特開20 07-233343號之實施例1的光擴散薄片用 3 00 #厚之PET製作成比較薄膜6。 •〔評價〕 接著，針對製作之實施例及比較例的薄膜，利用下述 方法評價燈管影像隱蔽性及光利用效率。結果示於表1。 又，內部散射層之黏結劑的折射率是調製在上述各內 部散射層塗布液中除了粒子的組成物，用棒狀塗布由此組 成物形成厚度40y m的層，以多波長阿貝折射計（DR-M2、 Atago(股）製）測定。測定波長爲5 89nm、測定溫度爲25°C。 又，粒子的折射率是在載玻片上載置粒子群，添加折 射率爲既知的有機化合物或其混合物（測定用化合物），以 以蓋玻片夾住後，在25°C用（透射）光學顯微鏡觀察，決定 粒子群變得最不易看見時之測定用化合物的種類或組成， 以多波長阿貝折射計（DR-M2、（股）Atago製）測定此測定用 化合物的折射率。測定波長爲5 8 9nm、測定溫度爲25°C。 內部散射層的平均折射率N3是由以上述測定方法所 得之黏結劑的折射率、及粒子的折射率’根據上述方法算 出。 <粒徑之測定方法> 在本檢討之粒徑是表示體積平均粒徑，在此體積平均 粒徑之測定是用粒度分布測定裝置（例如，Multisizer II 型、Coulter(股）製）進行測定。又’氧化鈦等凝聚強的粒子 -33- 201142367 是由適當電子顯微鏡的圖像測定粒徑並進行計算之方法來 進行。 <燈管影像隱蔽性之評價> 將各薄膜***取代LED照明（夏普公司製、DL-N002N) 的附屬擴散板’進行評價。又，各光擴散薄膜係以表面形 狀層設置在離照明器具較遠側的方式來.配置。 燈管影像隱蔽性之評價是對安裝有薄片的實機，從正 面約lm的距離用CMOS照相機（lumenera公司製、infinity) 攝影’將攝影圖像輸入圖像處理軟體，測定在定軸方向除 去所切出之亮度値的最極端部分的亮度極大値之平均（平 均極大値）與亮度極小値之平均（平均極小値），定義爲平均 極小値/平均極大値。在第8圖顯示在光擴散薄膜之面內以 定軸法之測定位置A中，測定到亮度極大値及亮度極小値 時的一實例。 . 由目視評價’平均極小値/平均極大値超過9 0 %時，幾 乎看不到燈管影像。 <光利用效率之評價> 將各薄膜***取代LED照明（夏普公司製、DL-N002N) 的附屬擴散板’進行評價。又，各光擴散薄膜係以表面形 狀層設置在離照明器具較遠側的方式來配置。. 根據一般工業規格（JIS-C8152(2007年度版），進行利用 積分球式光透射率測定裝置之評價。將未***薄膜時的全 光束當作1，評價***薄膜後的實測値（％)當作光利用效率。 -34- 201142367 表1 實施 實施 實施 實施 實施 實施 實施 實施 實施 例1 例2 例3 例4 例5 例6 例7 例8 例9 結構 第1圖 第2圖 第3圖 第4圖 第2圖 第7圖 第1圖 第1圖 第1圖 平均 粒徑 2 2 2 2 2 2 2 0.5 3.5 內 粒子 部 含有 散 量[份] 射 層 (相 對於 101 101 101 101 101 101 11 25 101 100份 黏結 劑） 隱蔽性[%] 93 93 93 93 93 93 90 93 93 光利用效 率[Ή 88 87 87 90 87 88 89 87 87 -35- 201142367 表2 比較例1 比較例2 比較例3 比較例4 比較例5 比較例6 構成 第1圖 第1圖 第5圖 第6圖 平均粒徑 內 [βτη] 0.3 6.5 2 2 2 5.2 部 粒子含有量 散 [份] 射 (相對於100 20 101 101 101 2 27 層 部黏結劑） 隱蔽性[%] 92 93 93 93 10 91 光利用效率[%] 80 84 85 81 90 . 85 由表1的結果可判斷實施例1〜9的LED照明用光擴散 薄膜係隱蔽性大而且光利用效率的降低爲少。相對於此， 可判斷內部散射層所含的粒子的平均粒徑爲0.3 // m的比較 例1、平均粒徑爲6.5 // m的比較例2、及平均粒徑爲5.2 μ m 的比較例6，則是當設計光擴散薄膜使得隱蔽性成爲大致 相同時，光利用效率會降低。又，在2片基板之間未設置 內部散射層的比較例3、或未設置表面形狀層之比較例4 即使以使隱蔽性成爲大致相同的方式進行設計時，也認爲 光利用效率降低。 又，如實施例5所示，縱使改變基板之種類，滿足本 發明之結構者仍可謀求高隱蔽性與光利用效率之兼備。 另一方面，日本專利第3993980號的光擴散薄片（比較 -36- 201142367 例5)，其係設計爲能夠從投影器之 投影器所投影的映像的背面投射之 性小，無法完全消除燈管影像。 <關於剛性> 作爲剛性之表現指標’通常已 或彎曲彈性模數（ns K7 171)。在本 所致之應變量，在一定尺寸且施加 知通常係與膜厚的3次方成反比。 時，應變會減少爲1 /8。如此一來， 而可大幅減少應變量。 參照日本申請號20 1 0-79876之 本說明書。 本說明書所記載之全部文獻、 格係經由參照各文獻、專利申請案 與具體且個別記載的情況相同地藉 中。 【圖式簡單說明】 第1圖係顯示本發明之LED照 例之示意截面圖》 第2圖係顯示本發明之LED照 實例之示意截面圖。 第3圖係顯示本發明之LED照 實例之示意截面圖。 反對側隔著營幕觀看從 透射型螢幕’則是擴散 知楊格模數UIS K7161) 檢討中，重要的因彎曲 一定應力的情況下，已 因此，將膜厚作成2倍 藉由貼合使膜厚增厚， 揭示內容其整體，倂入 專利申請案、與技術規 與技術規格而倂入，其 由參照而倂入本說明書 明用光擴散薄膜的一實 明用光擴散薄膜的其他 明用光擴散薄膜的其他 -37- 201142367 第4圖係顯示本發明之LED照明用光擴散薄膜的其他 實例之示意截面圖。 第5圖係顯示實施例中比較薄膜3的層結構之示意截 .面圖。 第6圖係顯示實施例中比較薄膜4的層結構之示意截 面圖。 第7圖係顯示實施例中薄膜6的層結構之示意截面圖。 第8圖爲在實施例中燈管影像之隱蔽性之評價方法， 用以說明亮度極大値之平均値及亮度極小値之平均値的 圖。· 【主要元件符號說明】 10，12 基 板 14, 16 內 部 散 射 層 18 黏 著 層 20 表 面 形 狀 層 22 低 折 射 率 層 -38-BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light diffusing film for LED lighting which has both concealability and light use efficiency while providing rigidity. [Prior Art] Based on the background of technology growth and energy consumption in recent years, LEDs have begun to enter the field of illumination. As a point which is quite different from the incandescent bulbs and fluorescent lamps of illumination to date, LEDs are point light sources. Therefore, in the case where the LED is used as the illumination, a light-diffusing film having a large concealing property and high light utilization efficiency is used (for example, refer to Japanese Laid-Open Patent Publication No. 2009-32563) to eliminate the lamp image of the point light source. However, in general, when the concealment property is increased, the efficiency is greatly reduced, and thus the concealability and the light utilization efficiency are both difficult. Further, when it is used for illumination, in order to prevent falling, it is necessary to have rigidity which is not deflected by wind pressure or pressing. However, when a plurality of light-diffusing sheets are usually bonded to impart rigidity, light efficiency is reduced by reflection of the bonding portion. In the case of a light diffusing sheet, for example, it has been disclosed in a transmissive screen projected on the back side (which is capable of viewing an image projected from a projector from the opposite side of the projector through a screen), having a transparent adhesive, The relative refractive index η with an average particle diameter of 1.0 to 10//m and a refractive index with respect to the transparent adhesive is 0.91. <n <1.09 (n=l) The front-scattering light-scattering layer of the spherical fine particles, and the image sharpness is 60.0% or more (for example, refer to Japanese Patent No. 3,993,980). In this transmission type screen, there is disclosed a light scattering layer having a scattering property in which the incident light is almost completely scattered to the front direction and is not scattered back to the front, and the light scattering layer is The adhesive layer is held together between the two transparent bodies. Further, in a light-diffusing sheet for use in a backlight unit of a liquid crystal display device, a light-diffusing layer in which a group of fine particles is dispersed in a light-transmitting resin is formed on a surface of a transparent film. a light-diffusing sheet in which a light-collecting layer in which a fine particle group is embedded in a light-transmitting resin is formed on the light-diffusing layer, and an absolute value of a refractive index difference between the light-transmitting resin and the fine particle group constituting the light-diffusing layer is 0.05 or more. Further, the surface roughness of the light-concentrating layer is 0.5 wm or more and 7 μm or less in terms of arithmetic mean roughness (for example, refer to JP-A-2007-23 3343). Disclosure of the Invention Problems to be Solved by the Invention In view of the above problems, an object of the present invention is to provide a light-diffusing film which has both high concealability and light use efficiency. Means for Solving the Problem It has been found by the inventors of the present invention that two layers of an internal scattering layer and a surface shape layer containing particles are provided, and an internal scattering layer is provided on the inner side when the substrate is bonded, and a surface is provided on the outer side of the substrate. In the shape of the inner layer, the inner scattering layer provided on the inner side contains particles having a specific particle diameter A within a specific range, whereby the light-diffusing film for LED illumination having a large concealing property and a small reduction in light use efficiency and having rigidity can be obtained. That is, the present invention is as follows. <1> The light-diffusing film for LED illumination has at least two substrates, and 201142367 has at least an average particle diameter a between the two substrates, and the inside of the particles and the binder satisfying the following formula (1) The scattering layer and the surface shape layer provided with at least the particles and the binder provided on the outer surface of the substrate. Formula (1) 0.5emSAS5.0/zm <2> as described above <1> The light-diffusing film for LED lighting according to the above aspect, wherein the content of the particles in the internal scattering layer is from 10 parts by mass to 120 parts by mass based on 100 parts by mass of the binder. <3><1> or The light-diffusing film for LED illumination according to any one of the above-mentioned, wherein the particles in the internal scattering layer have organic particles having a crosslinked structure. <4><1>~ The light-diffusing film for LED illumination according to any one of the above-mentioned, wherein the internal scattering layer contains a crosslinking agent. <5><1>~ The light-diffusing film for LED illumination according to any one of the invention, wherein the internal scattering layer has a refractive index of 1.40 or more and 1.00 or less. <6><1>~ The light-diffusing film for LED illumination according to any one of the above-mentioned items, further comprising an adhesive layer. <7> The light-diffusing film for LED illumination according to the above aspect, wherein the average refractive index N3 of the internal scattering layer satisfies the following formula with respect to the refractive index N 1 of the adjacent substrate and the refractive index N2 of the adhesive layer ( 2). Formula (2) N2 <N3 S N1 <8><1>~ The light-diffusing thin film for LED illumination according to any one of the above-mentioned embodiments, wherein the outer surface of the substrate on which the surface shape layer is not provided has a layer having a refractive index lower than that of the substrate. <9><1>~ The light-emitting thin film for LED lighting according to any one of the above-mentioned surface shape layer, wherein the surface layer has a layer having a refractive index lower than a refractive index of particles contained in the surface layer. <1〇><1>~ The light-diffusing film for LED illumination according to any one of the invention, wherein the binder in the internal scattering layer and the binder in the surface layer layer are selected from the group consisting of water-soluble polymers and water-dispersible polymers. At least one. <11><1>~ The light-emitting thin film for LED lighting according to any one of the above-mentioned, wherein at least one of the substrates is a PET film. <12><1>~ The light-diffusing film for LED illumination according to any one of the above-mentioned, wherein the substrate on which the surface layer is provided is a PET film. <13> The light-diffusing film for LED illumination according to any one of the above-mentioned, wherein the substrate on which the surface layer is not provided is made of a material having a lower refractive index than the PET film. <14> The light-diffusing film for LED illumination of any one of the above-mentioned PET film is provided with an internal scattering layer. <15><11>~ The light-diffusing film for LED illumination according to any one of the above-mentioned, wherein the PET film is a biaxially stretched film. According to the present invention, even when two or more substrates are bonded to each other to impart rigidity, it is possible to provide a light-diffusing film which is highly concealable, can easily eliminate LED tube images, and can suppress a decrease in light use efficiency of 201142367. [Embodiment] The light-diffusing film for LED illumination of the present invention (hereinafter sometimes abbreviated as r-light-diffusion film) has at least two substrates, and at least the average particle diameter A is between the two substrates. The internal scattering layer of the particles and the binder of the following formula (1) and the surface layer of at least the particles and the binder provided on the outer surface of the substrate are provided. In the light-diffusing film for LED lighting of the present invention, the reason why the concealing property is large and the reduction in light use efficiency can be suppressed is not clear, but it is presumed as follows. When two or more substrates are bonded together, an internal scattering layer containing particles having the specific average particle diameter described above is provided inside the bonding layer of the substrate, whereby the reflection at the interface of the bonding portion is suppressed by the presence of the internal scattering layer. Further, a surface layer containing particles is provided on the outer surface of the substrate to improve concealability and improve light use efficiency. Further, the adhesive in the internal scattering layer has adhesiveness, and the internal scattering layer can also function as an adhesive layer, or can be provided with an internal scattering layer and an additional adhesive layer. The light-diffusing film of the present invention may further have other layers such as a back layer as needed. Fig. 1 is a schematic cross-sectional view showing an example of the light-diffusing film for LED illumination of the present invention. Further, in Fig. 1 to Fig. 4, it is shown that the internal scattering layer and the additional adhesive layer are provided in 201142367. The light-diffusing film shown in Fig. 1 has two substrates 10, 12' on which the internal scattering layers 14, 16 are respectively placed in contact with each other. Furthermore, the two inner scattering layers 14, 16 are adhered by an adhesive layer 18. Further, in the substrate 12, the surface-shaped layer 20 is provided on the opposite surface to the surface on which the internal scattering layer 16 is provided. The light-diffusing film for LED illumination shown in FIG. 2 has two substrates 10, 12, The adhesive layer 18, the internal scattering layer 16, and the substrate 12 are sequentially provided from the substrate 10. Further, in the substrate 12, a surface shape layer 20 is provided on the surface opposite to the surface on which the internal scattering layer 16 is provided. The light-diffusing film for LED illumination shown in Fig. 3 has two substrates 10 and 12, and the internal scattering layer 16, the adhesive layer 18, and the substrate 12 are sequentially provided from the substrate 10. Further, in the substrate 12, a surface shape layer 20 is provided on the surface opposite to the surface on which the adhesive layer 18 is provided. . In the light-diffusing film for LED illumination shown in Fig. 4, the low-refractive-index layer 22 is further provided on the outermost surface of the light-diffusing film for LED illumination shown in Fig. 1. Further, Fig. 4 is a view showing a configuration in which the light-diffusing film for LED illumination of Fig. 1 is provided with the low-refractive-index layer 22, but it is needless to say that the light-diffusing film for LED illumination of Fig. 2 or Fig. 3 may be provided. The structure of the low refractive index layer 22. Further, in the fourth drawing, the low refractive index layer 22 is provided on both the surface of the outermost surface layer 20 and the surface of the substrate 10, and may be provided only on one side. In the light-diffusing film for LED illumination of the present invention, a more preferable layer structure is as shown in Fig. 1, in which the internal scattering layer 丨6 is placed between the substrates 10 and 12 in the form of 201142367. By such a layer structure, the refractive index difference of the substrates 10, 12 is alleviated by the internal scattering layer 16, and the reflection at the interface is effectively suppressed, thereby improving the light use efficiency. In particular, when the adhesive layer 18 is provided, since the refractive index of the adhesive layer 18 is often different from the refractive index of the substrate 1 〇, 12, it is meaningful to provide the internal scattering layer of the present invention. The members constituting the light-diffusing film for LED lighting of the present invention will be described in detail below. <Substrate> The substrate is not particularly limited as long as it is transparent and has a certain degree of strength. The plastic or glass used as a normal substrate can be appropriately selected according to the purpose, and particularly preferably a plastic. As the plastic, for example, polyester, polyolefin, or the like can be suitably cited. The polyester may, for example, be polyethylene terephthalate (PET, refractive index 1.67) or polyethylene naphthalate (PEN). Examples of other plastics include polyamine polyether, polystyrene, polyester decylamine, polycarbonate, polyphenylene sulfide, polyether ester, polyvinyl chloride, polyacrylate, polymethacrylic acid. Ester and the like. Among these, a polyester resin is preferable, and at least one of the substrates is more preferably composed of polyethylene terephthalate (PET). The polyethylene terephthalate (PET) used as the substrate is preferably obtained by melt-extruding a polyester resin into a film shape and biaxially stretching in the longitudinal direction and the transverse direction. Since the crystallization is coordinated by biaxial stretching and the strength and heat resistance are improved, it is suitable for use as a substrate for a light-diffusing film for LED illumination. The stretching ratio is not particularly limited, but is extended in the vertical and horizontal directions by 201142367 β ' is better than that of the double circumference method. It is better to choose the extension and thickness. Evenly right, the left and the parts, the strips, and the strong method are thinner for the mechanical parts. The same can be used when the substrate is made of polyethylene terephthalate and the other substrate is other plastic. Preferably, the substrate with the surface shape layer is made of polyethylene terephthalate. The substrate near the side of the lighting fixture is made of other plastic. For other plastics used for substrates on the side of the lighting fixture, it is preferred to use a material having a lower refractive index than polyethylene terephthalate (PET). For example, polycarbonate is preferably used. 1.58), a polyacrylic acid methyl ester (refractive index 1.50) and the like. Further, when the substrate 12 on which the surface layer is provided is made of polyethylene terephthalate (PET) and the substrate 1 near the lighting fixture side is made of another plastic, as shown in FIG. 1 and FIG. 2, it is adjacent to each other. The provision of the internal scattering layer 16 on the PET film substrate 12 can alleviate the difference in refractive index between the PET film substrate 12 and the adhesive layer 18, suppress reflection at the interface, and the like, and is suitable from the viewpoint of improving light use efficiency. The thickness of the substrate is not particularly limited as long as it is a range generally used as the substrate. The thickness of the substrate is preferably selected in accordance with the purpose, and is preferably 0.02 mm to 4.0 mm. On the surface of the substrate, in order to improve adhesion to the internal scattering layer or the surface layer, discharge treatment may be performed. <Internal scattering layer> -10- 201142367 The internal scattering layer is used to exhibit the light diffusing function and the gastric particles and the binder. The average particle size A of the particles satisfies the following formula (1) ° Formula (1) 0.5/z 5.0^ m When the light diffusing film is designed to be substantially the same as the concealing rate for eliminating the image of the lamp, the internal scattering When the average particle diameter A of the particles contained in the layer is less than 0.5 am, the scattering function is lowered or the back scattering is increased to significantly reduce the light use efficiency, and the light use efficiency is also lowered when it exceeds 5.0 // m. The components contained in the internal scattering layer will be described in detail below. (Particles) The particles contained in the internal scattering layer are as described above, and the average particle diameter A satisfies the above formula (1), and more preferably the average particle diameter A is in the range of l#m or more. The material of the particles is not particularly limited, and may be appropriately selected according to the purpose, and examples thereof include organic particles such as polymethyl methacrylate resin particles, melamine resin particles, polystyrene resin particles, and polyfluorene resin particles. . These may be used alone or in combination of two or more. It is preferred that the organic particles have a crosslinked structure. Further, the organic particles may be coated with a surface. For example, particles coated with vermiculite or the like may be suitably used, and the surface may be hydrophilized or hydrophobized depending on the type of the coating liquid. The amount of the particles to be added is preferably from 1 〇 to 1 20 parts by mass based on 100 parts by mass of the following binder. When the amount of the particles -11 - 201142367 is within the above range, the particle dispersibility in the binder is good, and the function as a light diffusing agent can be sufficiently exhibited. The amount of the particles added is preferably from 10 to 1 1 part by mass, more preferably from 10 to 105 parts by mass, per 100 parts by mass of the binder. (Binder) In the present invention, the binder means all solid components (including ultrafine particles described later) in addition to the above particles in the internal scattering layer. Specifically, it includes a resin, ultrafine particles, other additives, and the like. Specifically, the refractive index of the binder is preferably 1.4 Å or more and 1.7 or less, more preferably 1.40 or more and 1.60 or less. - Resin - When the resin is used as a dispersion medium for the internal scattering layer coating liquid, for example, at least one resin selected from the group consisting of a water-soluble polymer and a water-dispersible polymer is preferably used. As the binder resin, a single polymer or a copolymer or the like is suitably exemplified. The above-mentioned individual polymer or copolymer may, for example, be a (meth)acrylic acid resin, a vinyl acetate resin, an ethylene-vinyl acetate copolymer resin, a chloroethene resin, a vinyl chloride-vinylidene chloride copolymer resin. , butyral resin, polyoxymethylene resin, polyester resin, vinylidene fluoride resin 'nitrocellulose resin, styrene resin, styrene-acrylonitrile copolymer resin, polyurethane resin, polyethylene, Polypropylene, chlorinated polyethylene, rosin derivatives, and the like. The sphagnum and/or water-dispersible polymer is not particularly limited and may be appropriately selected according to the purpose. -12- 201142367 For example, polyvinyl alcohol, methyl cellulose, gelatin, polyester resin, polyurethane resin, acrylic resin, amine resin, epoxy resin, styrene butadiene A water-soluble or water-dispersible polymer such as an olefin copolymer is preferably a water-dispersible polymer of an acrylic resin type, a polyester resin type or a polyurethane resin type. These may be used alone or in combination of two or more. Further, it is preferred to use a polymer which can react with a crosslinking agent. For example, a polymer having a hydroxyl group, an amine group, a carboxyl group or the like can be used. Further, the water-dispersible polymer preferably contains a substituent such as a sulfonic acid group, a hydroxyl group, a carboxylic acid group, an amine group, a decylamino group or an ether group. Further, these water-dispersible high molecular weight systems may be used singly or in combination. Further, in the case of functioning as an adhesive layer, a resin described in the following adhesive layer may be used as the resin of the internal scattering layer. Further, in order to provide the scratch resistance at the time of the treatment, the solvent resistance of the solvent for wiping the dust or the dirt adhering to the surface, and the sealing of the light-diffusing film for LED illumination into a predetermined form, the substrate is adhered to the substrate. Preferably, a crosslinking agent for hardening the film is added to the internal scattering layer. -Other Additives - In order to provide the scratch resistance at the time of the treatment, the solvent resistance of the solvent for wiping the dust or the dirt adhering to the surface, and the press-forming of the light-diffusing film for LED lighting into a predetermined form, The adhesion of the substrate is preferably such that a crosslinking agent for hard film is added to the internal scattering layer. - Crosslinking agent - 13- 201142367 In terms of the aforementioned crosslinking agent, a carbodiimide compound or an isocyanate compound is more preferable as the carbon quinone imine compound. The carbodiimide compound used in the present invention has a carbodiimide group in the molecule', for example, by reacting with a carboxyl group of a polyester resin to form an amine carbaryl amide bond, or by using a polyester The reaction of the hydroxyl group of the resin forms a chemical structure such as an isourea bond. Further, in terms of the chemical structure, the fox structure formed upon reaction with the amine group is also included. For general commercial products, Nisshinbo's Carbodilite E series (emulsion type), V series (aqueous type), and the like can be used. As the isocyanate compound, at least two of an aliphatic isocyanate compound, a cyclic aliphatic isocyanate compound, and an aromatic polyfunctional isocyanate compound having at least two, preferably three or more functional groups in the molecule can be used. One. The isocyanate compound is described in the "Handbook of Polyurethane Resins" (edited by Iwata Katsuyuki, published by Nikkan Kogyo Shimbun, 1 987). These crosslinking agents can be used alone or in combination of two or more. - Ultrafine particles - Further, for example, ultrafine particles composed of inorganic particles may be added to the internal scattering layer as other particles. The above ultrafine particles can improve the coating suitability and control the refractive index of the binder. The ultrafine particle system is not particularly limited, and a commonly used substance can be appropriately selected and dispersed according to the purpose. For example, vermiculite, calcium carbonate, aluminum oxide, zirconium oxide, titanium oxide, or the like can be mentioned. The particle size of the ultrafine particles is preferably in the range of 0.005 em to 0.150 / zm, more preferably in the range of 0.005 / zm to 0.100 / / m. The amount of the ultrafine particles to be added to the internal scattering layer is not particularly limited, and may be appropriately determined depending on the situation, and is preferably, for example, 20% by mass. - Solvent - The solvent used in the internal scattering layer coating liquid is not particularly limited, and may be appropriately selected from ordinary users such as water or an organic solvent. Examples of the organic solvent include ketones, ethers, alcohols, esters, polyhydric alcohol derivatives, and carboxylic acids. The internal scattering layer is formed by applying the internal scattering layer coating liquid onto the adhesive layer and then drying it. The internal scattering layer may be provided with only one layer or two or more layers. The coating method of the internal scattering layer coating liquid is not particularly limited, and may be appropriately selected according to the purpose, and may be carried out by a coating means such as a spin coater, a roll coater, a bar coater, or a curtain coater. The drying method of the internal scattering layer coating liquid is not particularly limited, and a generally used method can be appropriately selected depending on the type of the solvent to be used. For example, when water is used as the solvent, the drying temperature is preferably from 90 ° C to 140 ° C and more preferably from 10 ° C to 140 ° C in terms of short-term damage to the material. The drying temperature is not required to be dried for a long time -15 to 201142367, and the damage to the material can be suppressed. For the drying time, for example, it is preferably 10 seconds to 5 minutes, more preferably 1 minute to 3 minutes. (physical properties, etc.) From the viewpoint of achieving the effect of light scattering and efficiency, the thickness of the internal scattering layer is preferably l; am to 20/zm. The refractive index N1 of the substrate and the refractive index of the adhesive layer described later. N2, the average refractive index N3 of the internal scattering layer preferably satisfies the following formula (2). Formula (2) N2 <N3 ^ N 1 Here, the average refractive index N3 is a refractive index of the binder (solid components other than particles), and the volume ratio of the solid content of each binder is regarded as Vi. The enthalpy calculated by Ni* Vi. By satisfying the formula (2), the refractive index N3 of the internal scattering layer becomes 値 between the refractive index N 2 of the adhesive layer and the refractive index N 1 of the substrate. By the presence of the internal scattering layer having such a refractive index, the refractive index difference between the adhesive layer and the substrate is moderated, and the reflection at the interface is effectively suppressed, and the light use efficiency is improved. Specifically, the refractive index N3 of the internal scattering layer is preferably 1.50 to 1.67, more preferably 1.50 to 1.60. From the viewpoint of suppressing the reflection of the interface between the substrate and the internal scattering layer and improving the light use efficiency, the difference between the refractive index N1 of the substrate and the refractive index N3 of the internal scattering layer is preferably 〇~ο. From the viewpoint of suppressing the reflection of the interface between the adhesive layer and the internal scattering layer and improving the light utilization efficiency, the difference between the refractive index Ν2 of the adhesive layer and the refractive index Ν3 of the internal scattering layer described later is 〇~〇.1 It is better. -16- 201142367 <Adhesive layer> As described above, when the internal scattering layer has the function of an adhesive layer, it is not necessary to provide an adhesive layer. However, when an adhesive layer is provided, the following components may be used. The adhesive layer may be an acrylic type, an urethane type, an epoxy type, or a polyoxyl type, and is not particularly limited, and may be appropriately selected according to the purpose. Specifically, the commercially available product of the laminated layer is, for example, a dry type of a two-liquid system which can be used by adding an isocyanate-based curing agent of LCR-901 to an amino carboxylic acid vinegar-based main agent of LIS805 manufactured by Toyo Ink Co., Ltd. Laminated material. Further, as for the laminate, a material suitable for the extrusion method or the hot melt method can be suitably used. The refractive index N2 of the adhesive layer preferably satisfies the above formula (2), and specifically, 1.5 to 1.67 is preferable. The thickness of the adhesive layer is preferably lvm~50/zm and lym~2//m from the viewpoint of non-destructive light transmittance and adhesion. <Surface shape layer> The surface shape layer contains at least particles and a binder. (Binder) For the binder contained in the surface layer, the same one as the binder described in the % scattering layer can be applied. (Particles) The material of the particles contained in the surface layer is not particularly limited, and may be appropriately selected according to the purpose. For example, polymethyl-17-201142367 methyl acrylate resin particles, melamine resin particles, and poly Organic particles such as styrene resin particles and polyoxyxylene resin particles. These may be used alone or in combination of two or more. The average particle diameter B of the particles contained in the surface layer is preferably in the range of 0.5 Å or more and 50/zm or less, more preferably in the range of 3/zm or more and 20 Å or less. Further, the average particle diameter Β of the particles contained in the surface shape layer is larger than the average particle diameter Α of the particles contained in the internal scattering layer, which is determined by the fact that the change in color tone in the white LED light source is reduced. Preferably. Specifically, the average particle diameter B is preferably 1 # m or more larger than the average particle diameter A, and more preferably 3 μm or more. The amount of the particles to be added is preferably 5 parts by mass to 400 parts by mass, more preferably 50 parts by mass to 30,000 parts by mass, per 100 parts by mass of the above-mentioned binder resin. When the amount of the particles added is within the above range, the particle dispersibility in the binder becomes good, and the function as a light diffusing agent can be sufficiently exhibited. (Other additives) In the same manner as the internal scattering layer, a crosslinking agent, ultrafine particles, a solvent or the like may be further added to the surface layer. The types of the crosslinking agent, the ultrafine particles, and the solvent to be added to the surface layer are the same as those of the crosslinking agent, (ultrafine particles), and solvent described in the internal scattering layer. The amount of the ultrafine particles added to the surface shape layer is not particularly limited, and the desired total light transmittance and the half 値-18 - 201142367 angle are obtained as described above, and can be appropriately selected depending on the situation, for example, 1 to 20 The mass % is preferred. The surface shape layer can be formed by the same method as the above internal scattering layer. (Physical properties, etc.) From the viewpoint of achieving the light scattering effect, the thickness of the surface shape layer is preferably 2 " m~30 μm, more preferably 2//m~20# m. <Low-refractive-index layer> The light-diffusing film for LED illumination of the present invention may have a low-fold layer 22 on the surface of the outermost layer. Here, the low refractive index layer means a layer having a refractive index lower than that of the layer (e.g., the substrate 10 or the surface shape layer 20) which is disposed in contact with each other. By providing the low refractive index layer 22, interface reflection with air can be suppressed, and light efficiency can be improved. The refractive index of the low refractive index layer provided on the substrate as the outermost surface is preferably 0.1 or more and 0.15 or more smaller than the refractive index of the substrate. Specifically, the refractive index of the low refractive index layer provided on the substrate is preferably from 1.30 to 1.50, more preferably from 1.30 to 1.45. Further, the refractive index of the low refractive index layer provided on the outermost surface layer is preferably smaller than the refractive index of the particles contained in the surface layer. 0 1 or more and 0.05 or less are more preferable. .1〇 or more is further better. Specifically, the refractive index of the low refractive index layer provided on the surface shape layer is preferably 1.30 to 1.50, more preferably 1.30 to 1.45. -19- 201142367 The material used for the low refractive index layer is a fluorine-based material such as CytopCTL-107MK (refractive index 1, 34) manufactured by ASAHI GLASS Co., Ltd., or a vermiculite aerogel. A porous membrane or a micro hollow particle. The thickness of the low refractive index layer is preferably 0.05//m to 2.00 vm, more preferably 0.05//m to 1.00/U m . <Manufacturing Method of Light-Diffusing Film for LED Illumination> The method for producing a light-diffusing film for LED illumination of the present invention is not particularly limited as long as it can form the light-diffusing film for LED illumination having the above configuration. An example of a method of producing a light-diffusing film for LED lighting will be described below. First, an internal scattering layer coating liquid containing at least the particles and a binder is applied onto a substrate to form an internal scattering layer, and a surface layer coating liquid containing at least particles and a binder is applied onto the surface of the substrate on the side where the internal scattering layer is not provided. A surface shape layer is formed. This is referred to as a first film prepared in advance. Then, another substrate on which the internal scattering layer is formed or a substrate on which no internal scattering layer is provided is prepared. This is called a second film. The internal scattering layer of the first film prepared, the internal scattering layer of the second film, or the substrate not provided with the internal scattering layer is adhered by an adhesive. When the light-diffusing film for LED illumination of the present invention is provided with a low refractive index layer, it is adhered by the above-mentioned adhesive, immersed in a coating liquid of a low refractive index layer, or dried after application. <Applications> The light-diffusing film for LED illumination of the present invention can be suitably used in a device using LED illumination by virtue of its advantages, -20-201142367. Further, a light diffusing film of a backlight unit of a liquid crystal display device such as a mobile phone, a monitor for a personal computer, a television, or a liquid crystal projector can be exemplified. In addition, when the light-diffusing film for LED illumination of the present invention is used, it has high concealability and light use efficiency, so that the LED image is used to eliminate the image of the lamp, and the use efficiency of the light is maintained, and the device can be used for a long time. Life expectancy. Here, the term "light use efficiency" as used herein refers to the measured enthalpy (%) after the un-inserted full beam is regarded as 1 and inserted into the film. Although it has been achieved as a single illuminating device as a single illuminating device, it has been reduced in light utilization efficiency due to the shape of the heat and current converter, and there is still a lighter glimmer that is still inferior to the conventional one. The condition of the light. In the future, the use of mercury in the use of mercury is only in the environmental level such as mercury and the superiority of energy consumption such as light efficiency, and it has been extremely appealing to the illumination to date, because it is a difference in light utilization efficiency of 1%. The embodiments of the present invention are also described in the following. However, the present invention is not limited by the examples. In addition, in the following description, unless otherwise specified, "%" means "parts by mass" and "mass%". [Example 1] <Production of Film 1 A> In order to use it in the line, the film can be used today, but the efficiency of the film and the light can be achieved without the appearance of a large difference. 21 - 201142367 On a PET film (refractive index of 1.67) having a thickness of 300 μm, the internal scattering layer coating liquid 1 of the following composition was applied by a wire bar and heat-hardened in an oven at 130 ° C for 2 minutes. Composition of coating liquid 1) • Distilled water: 80 parts by mass • Surfactant (Sanyo Chemical Industry Co., Ltd., Naroacty CL-95): 5 parts by mass ♦ particles (Nissan Chemical Co., Ltd., Optbeads 2000M, vermiculite coated with melamine Particles, average particle size 2 μ m, refractive index 1.65): 20 1 part by mass • Ultrafine particle dispersion (Nissan Chemical Industry Co., Ltd., Snowtex C, vermiculite particles, average particle size 0.01/zm~0.02; am, Solid component 20%): 333 parts by mass • Water-dispersible polymer (polyurethane resin, manufactured by DMS NeoResins Inc., NeoRezR-600, solid content: 33%): 368 parts by mass • Crosslinker (Nisshinbo ( Stock system, Carbodilite V-02-L2, solid content 40%) : 12 parts by mass of a portion of the coating film obtained by peeling off, and the film thickness was measured by a height difference meter (manufactured by Dektak Veeco Co., Ltd.), and the average film thickness was 2 vm. Here, the film thickness was peeled off by any three positions. The height difference between the surface of the substrate and the coating film was measured, and the average enthalpy was measured. Further, in each measurement, the surface of the coating film was measured at a distance of 500 Å to calculate the average film thickness of the surface having irregularities. In the examples, the film thickness was measured by this method. Further, on the surface of the PET film opposite to the surface coated with the internal scattering layer coating -22-201142367 liquid 1, the following composition was coated with a wire bar. The surface shape layer coating liquid 1 was heat-hardened in an oven of TC for 2 minutes to obtain a film 1 A. The average film thickness of the surface shape layer was 6 μm. (Composition of the surface shape layer coating liquid 1) • Distilled water: 244 parts by mass • Surfactant (Sanyo Chemical Industry Co., Ltd.' Naroacty CL-95): 5 parts by mass • Particles (made by Sekisui Chemicals Co., Ltd., SBX-8, crosslinked polystyrene particles, average particle size 8 β m ' Refractive index 1.59): 264 quality Ultrafine particle dispersion (Nissan Chemical Industry Co., Ltd., Snowtex C, vermiculite particles, average particle size 0.01 to 0.02/zm, solid content 20%): 238 parts by mass • Water-dispersible polymer (polyamine group) Formate resin, manufactured by DMSNeo Resins Inc., NeoRezR-600, solid content 33%): 237 parts by mass • Crosslinking agent (made by Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%): 13 parts by mass <Production of Film 1B> The internal scattering layer coating liquid 1 was applied to a PET film (refractive index of 1.67) having a thickness of 300 // m by a wire bar, and heat-hardened in an oven at 130 ° C for 2 minutes to obtain a film. Film 1B. The internal scattering layer formed had an average film thickness of 2 em. <Production of Film 1> The adhesive was applied to the internal scattering layer of the film 1A at a thickness of 6/m. (manufactured by Toyo Ink Co., Ltd., LIS 8 05/LCR-901, refractive index: 1.50) -23- After 201142367, dry in an oven at 100 ° C for 5 minutes. After the adhesive layer was bonded to the internal scattering layer of 1B, the film was laminated at a pressure of 〇4 Mpa. [Example 2] <Production of Film 1D> The internal scattering layer coating liquid 1 was applied to a PET film (refractive index of 1.67) having a thickness of 300 μm, and the hard disk was heated in an oven at 130 °C. The internal scattering layer formed had an average film thickness of 4/zm. Further, on the surface of the PET film opposite to the surface on which the internal scattering liquid 1 is applied, the surface shape liquid 1 is coated with a wire bar, and heat-hardened in an oven at 130 ° C for 2 minutes to obtain a film surface layer. The average film thickness was 6 vm. <Production of Film 2> On the internal scattering layer of the film 1D, an applicator was used as a 6# cloth adhesive (manufactured by Toyo Ink Co., Ltd., LIS805/LCR-901, refraction), and then oven was used at 1 °C. After drying the film for 5 minutes, the adhesive layer was laminated (thickness: 1.67), and then laminated at a pressure of 0.4 MPa to form film 2. [Example 3] <Production of Film 1C> PET film having a thickness of 300 m ( The refractive index 1.67) was coated with the surface layer coating liquid 1 described above, and the hard clock was heated in an oven at 130 ° C to obtain a film 1 C. The average film of the formed surface shape layer was coated with a thin wire rod on the film. 2 layer coating layer coating 1 D. Table m thick coating 1.50) made of PET thin rods coated 2 points thick, -24- 201142367 6 vm 〇 <Production of Film IE> The internal scattering layer coating liquid 1 was applied to a PET film (refractive index of 1.67) having a thickness of 300 μm by wire. (: oven heating hardening clock) to obtain film 1E. The average thickness of the internal scattering layer formed is 6 <Production of Film 3> In the film 1C, on the surface opposite to the surface shape layer, the adhesive was applied at a thickness of 6 μm (Toyo Ink Co., Ltd. LIS 805/LCR-901, refractive index: 1.50), and then used. The oven is dry at l ° ° C minutes. The adhesive layer was laminated on the inner scattering layer side of the film 1 E, and laminated at a pressure of 0.4 MPa to obtain a film 3. [Example 4] <Production of Film 4> A film 1 was produced in the same manner as in Example 1. A liquid obtained by diluting Cytop (manufactured by ASHAIGLASS, CTL-107MK, or 1.34) in a diluted manner with the same product was spin-coated on both sides, at 100. The oven was made into a low refractive index layer for 30 minutes to obtain a film 4. A schematic view of the structure of the film 4 is shown in Fig. 4. [Example 5] <Production of Film 5> On the internal scattering layer of the film 1D, a 6/zm cloth adhesive was used by an applicator (made by Toyo Ink Co., Ltd., LIS 805/LCR-901, refractive index, and oven was used at 100 ° C). Dry for 5 minutes. Apply this adhesive layer to the rod and apply 2 points of β m. Coating decoction: dry 5, dry layer coating with liquid 4 rate 1.50) Polycarbon-25- 201142367 Acid ester (Panlite made by Teijin Chemicals) After Ll 225Y, refractive index 1.59), lamination was carried out at a pressure of 0.4 MPa to obtain a film 5. [Embodiment 6] <Production of Film 6> In the film 1C, the following adhesive 1 (internal scattering layer) was applied to the surface opposite to the surface shape layer by a coater at a thickness of 6 vm, and then dried at 100 ° C in an oven. 5 minutes. This adhesive layer was laminated on a PET film (refractive index of 1.67) having a thickness of 300 μm, and laminated at a pressure of 0.4 MPa to obtain a film 6. A schematic view of the layer structure of the film 6 is shown in Fig. 7. Adhesive 1 (internal scattering layer) • Solvent: MEK 415 parts by mass • Adhesive agent: LIS 805 (made by Toyo Ink Co., Ltd. · Solid content 50%) 35 0 parts by mass • Adhesive hardener: LCR-901 (Toyo Ink Manufacturing Co., Ltd., 70% solid content) 35 parts by mass • Particles (Nissan Chemical Co., Ltd., Optbeads 2000M, vermiculite coated melamine particles, average particle size 2# m, refractive index 1.65): 200 mass [Example 7] <Production of Film 7> The film 7 was produced in the same manner as in Example 1 except that the internal scattering layer coating liquid 2 described below was used instead of the internal scattering layer coating liquid 1 of Example 1. (Composition of Internal Scattering Layer Coating Liquid 2) • Distilled Water: 9 7 parts by mass -26- 201142367 • Surfactant (Sanyo Chemical Industry Co., Ltd., Naroacty CL-95): 6 parts by mass • Particles (Nissan Chemical ( Co., Ltd., 〇ptbeads 2000M, vermiculite coated melamine particles, average particle size 2 // m, refractive index 1.65): 26 parts by mass • Ultrafine particle dispersion (Nissan Chemical Industry Co., Ltd., Snowtex C, vermiculite particles) , average particle size 0.01 " m~0.02ym, solid content 20%): 408 parts by mass • water-dispersible polymer (polyurethane resin, DMSNeoResins Inc., NeoRezR-600, solid content 33%) : 448 parts by mass • Crosslinking agent (manufactured by Nisshinbo Co., Ltd., Carbodilite V-02-L 2, solid content: 40%): 15 parts by mass [Example 8] The following internal scattering layer coating liquid 3 was used instead of Example 1 The film 8 was produced in the same manner as in Example 1 except that the internal scattering layer coating liquid 1 was used. (The composition of the internal scattering layer coating liquid 3) • Distilled water: 94 parts by mass • Surfactant (Sanyo Chemical Industry Co., Ltd., Naroacty CL-95): 6 parts by mass • Particles (Nissan Chemical Co., Ltd. ), 〇ptbeads 500S, vermiculite coated melamine particles, average particle size 〇 _ 5 // m, refractive index 1.6 5): 5 9 parts by mass • ultrafine particle dispersion (Nissan Chemical Industry Co., Ltd., Snowtex C, Vermiculite particles, average particle size 〇·〇1 μm to 0.02 μm, solid content 20%): 392 -27- 201142367 parts by mass • Water-dispersible polymer (polyurethane resin, manufactured by DMSNeo Resins Inc., NeoRezR-6 00, solid content 33%): 434 parts by mass • Crosslinker (made by Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%): 14 parts by mass [Example 9] The film 9 was prepared in the same manner as in Example 1 except that the internal scattering layer coating liquid 4 was replaced with the internal scattering layer coating liquid 1 of Example 1 and the thickness of the internal scattering layer was changed from 2 #m to 3 μm. (Composition of Internal Scattering Layer Coating Liquid 4) • Distilled Water: 80 parts by mass • Surfactant (Sanyo Chemical Industry Co., Ltd., Naroacty CL-95): 5 parts by mass • Particles (Nissan Chemical Co., Ltd., 〇ptbeads 3500M) , meteorite coated with melamine particles, average particle size 3.5 # m, refractive index 1.65): 20 1 parts by mass. Ultrafine particle dispersion (Nissan Chemical Industry Co., Ltd., Snowtex C, vermiculite particles, average particle size 0.01// m to 0.02/zm, solid content: 20%): 333 parts by mass • Water-dispersible polymer (polyurethane resin, manufactured by DMS NeoResins Inc., NeoRezR-600, solid content: 33%): 368 parts by mass • Crosslinking agent (made by Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%): 12 parts by mass [Comparative Example 1] -28- 201142367 <Production of Film 2A> The internal scattering layer coating liquid 5 having the following composition was applied to a PET film (refractive index of 1.67) having a thickness of 300 μm by wire bar, and heat-hardened in an oven at 30 ° C for 2 minutes. . The internal diffusion layer formed had an average film thickness of 2/zm. (Internal scattering layer coating liquid 5) • Distilled water: 8 3 parts by mass • Surfactant (Kao Chemical, Femol's solid content 2 4 %): 2 4 parts by mass • Particles (Ishihara Industry Co., Ltd., CR) -50, titanium oxide particles, average particle diameter 0.3 am, refractive index 2.6 0): 48 parts by mass. • Ultrafine particle dispersion (Nissan Chemical Industry Co., Ltd., Snowtex C, vermiculite particles, average particle size 0·) 01~0.02# m, solid content 20%): 395 parts by mass • Water-dispersible polymer (polyurethane resin, DMSNeoResins Inc., NeoRezR-600, solid content 33%): 436 parts by mass A crosslinking agent (made by Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content of 40%): 14 parts by mass, further, on the opposite side of the surface of the PET film to which the internal scattering layer coating liquid 5 has been applied, The surface layer coating liquid was applied by a wire bar and heat-hardened in an oven at 130 ° C for 2 minutes to obtain a film 2A. The surface layer formed had an average film thickness of 6 μm. <Production of Film 2B> The inner scattering layer coating liquid 5 was coated on a PET film (refractive index of 1.67) having a thickness of 300 am by wire bar -29-201142367, and heat-hardened in a TC oven for 2 minutes. The film 2B was obtained. The internal scattering layer formed had an average film thickness of 2 μm. <Preparation of Comparative Film 1> The adhesive was applied to the internal scattering layer of the film 2Α by a coater at a thickness of 6/zm (manufactured by Toyo Ink Co., Ltd., LIS 805/LCR-901, refractive index: 1.50), and then at 100°. The oven of C was dried for 5 minutes. After the internal scattering layer of the film 2B was adhered to the adhesive layer, the film was laminated at a pressure of 0.4 Mp a to prepare a comparative film 1. [Comparative Example 2] <Production of Film 3A> The internal scattering layer coating liquid 6 having the following composition was applied to a PET film (refractive index of 1.67) having a thickness of 300 Å by a wire bar, and heat-hardened in an oven at 130 ° C for 2 minutes. The internal scattering layer formed had an average film thickness of 6 μm. Further, on the opposite side of the surface of the PET film to which the internal scattering layer coating liquid 6 has been applied, the surface layer coating liquid 1' is applied by a wire bar and heat-hardened in an oven at 130 ° C for 2 minutes. A film 3 A was obtained. The surface layer formed has an average film thickness of 6^111. (Internal scattering layer coating liquid 6) • Distilled water: 80 parts by mass • Surfactant (Beiyang Chemical Industry Co., Ltd., Naroacty CL-95): 5 parts by mass • Particles (Nissan Chemical Co., Ltd., Optbeads 6500M, 矽Stone coated melamine particles, average particle size 6.5 ym, refractive index 1.65): 20 1 part by mass -30- 201142367 • Ultrafine particle dispersion (Nissan Chemical Industry Co., Ltd., Snowtex C, vermiculite particles, average particle size 〇. 〇 0.02# m, solid content 20%): 333 parts by mass • Water-dispersible polymer (polyurethane resin, manufactured by DMS NeoResins Inc., NeoRezR-600, solid content 33%): 368 parts by mass '. Crosslinking agent (Nisshin Spinning Co., Ltd., Carbodilite V-02-L2, solid content 40%): 12 parts by mass <Production of Film 3B> The internal scattering layer coating liquid 6 was coated on a PET film (refractive index of 1.67) having a thickness of 300 m on a wire bar, and heat-hardened in an oven at 130 °C for 2 minutes to obtain a film 3B. The internal scattering layer formed had an average film thickness of 6 μm. <Preparation of Comparative Film 2> The adhesive was applied to the internal scattering layer of the film 3A by a coater at a thickness of 6 μm (manufactured by Toyo Ink Co., Ltd., LIS805/LCR-901, refractive index: 1.50), and then oven at 100 ° C. Dry for 5 minutes. After the adhesive layer was bonded to the inner scattering layer side of the film 3B, the film was laminated at a pressure of 0.4 MPa to obtain a comparative film 2. [Comparative Example 3] <Production of Film 4A> The internal scattering layer coating liquid 1 was coated on a PET film (refractive index 1.67) having a thickness of 300 // m by a wire bar, and heat-hardened in an oven of 1 30 tons for 2 minutes. The internal scattering layer formed had an average film thickness of 4 μm. Further, on the coated internal scattering layer, the surface shape layer coating liquid 1 described above was coated with a wire bar, and the film 4A was obtained by heating and hardening for 2 minutes in an oven of TC. The formed surface was formed. The average film thickness of the shape layer and the internal scattering layer was 10#m on average. <Preparation of Comparative Film 3> In the film 4A, an adhesive was applied at a thickness of 6/m on the opposite side of the surface on which the surface layer of the substrate was formed (Toyo Ink Co., Ltd., LIS805/ After LCR-901, refractive index 1.50), it was dried in an oven at 10 ° C for 5 minutes. After adhering the PET film (refractive index of 1.67) to the adhesive layer, the film was laminated at a pressure of 0.4 MPa to prepare a comparative film 3. A schematic view of the layer structure of the comparative film 3 is shown in Fig. 5. [Comparative Example 4] <Preparation of Comparative Film 4> After applying an adhesive (manufactured by Toyo Ink Co., Ltd., LIS805/LCR-901, refractive index: 1.50) to the internal scattering layer of the film 1E by a coater at a thickness of 6/m, Dry in an oven at l° °C for 5 minutes. After the adhesive layer was applied to the internal scattering layer of the film 1E, it was laminated at a pressure of 0 to 4 MPa to prepare a comparative film 4. A schematic view showing the layer structure of the comparative film 4 is shown in Fig. 6. [Comparative Example 5] <Production of Comparative Film 5> The comparative film 5 was produced in the same manner as in Example 1 of the specification of Japanese Patent No. 3939390. [Comparative Example 6] -32- 201142367 - <Preparation of Comparative Film 6> The light-diffusing sheet of Example 1 of pp. No. 20 07-233343 was made into a comparative film 6 using 300 Å thick PET. [Evaluation] Next, with respect to the films of the examples and the comparative examples produced, the lamp image concealability and the light use efficiency were evaluated by the following methods. The results are shown in Table 1. Further, the refractive index of the internal scattering layer is prepared by coating a composition having a thickness of 40 μm in a rod-like coating on the internal scattering layer coating liquid in addition to particles, and using a multi-wavelength Abbe refractometer (DR-M2, Atago system) measurement. The measurement wavelength was 589 nm, and the measurement temperature was 25 °C. Further, the refractive index of the particles is a particle group placed on a glass slide, and a known organic compound or a mixture thereof (a compound for measurement) having a refractive index is added to be sandwiched between coverslips, and then used at 25 ° C (transmission). The type and composition of the compound for measurement when the particle group became the least visible was determined by an optical microscope, and the refractive index of the compound for measurement was measured by a multi-wavelength Abbe refractometer (DR-M2, manufactured by Atago). The measurement wavelength was 589 nm and the measurement temperature was 25 °C. The average refractive index N3 of the internal scattering layer is calculated by the above method from the refractive index of the binder obtained by the above measurement method and the refractive index of the particles. <Measurement method of particle diameter> The particle diameter in the present review is a volume average particle diameter, and the volume average particle diameter is measured by a particle size distribution measuring device (for example, Multisizer II type, manufactured by Coulter Co., Ltd.). Determination. Further, a particle having a strong agglomeration such as titanium oxide -33- 201142367 is obtained by measuring the particle diameter from an image of an appropriate electron microscope and calculating it. <Evaluation of the concealability of the lamp image> Each film was inserted and replaced with an auxiliary diffusion plate of LED illumination (manufactured by Sharp Corporation, DL-N002N). Further, each of the light-diffusing films is disposed such that the surface-shaped layer is provided on the far side from the lighting fixture. In the evaluation of the concealability of the lamp image, the photographic camera (manufactured by Lumenera Co., Ltd., infinity) is photographed from the front side with a distance of about lm. The image is input into the image processing software, and the measurement is removed in the direction of the fixed axis. The brightness of the most extreme part of the cut luminance 値 is extremely large (average maximum 値) and the average of the minimum brightness (average minimum 値) is defined as the average minimum 値 / average maximum 値. Fig. 8 shows an example in which the maximum brightness 値 and the extremely small 値 brightness are measured in the measurement position A of the fixed-axis method in the plane of the light-diffusing film. By visual evaluation, when the average minimum 値 / average maximum 値 exceeds 90%, the tube image is almost invisible. <Evaluation of Light Use Efficiency> Each film was inserted and replaced with an auxiliary diffusion plate of LED illumination (manufactured by Sharp Corporation, DL-N002N). Further, each of the light-diffusing films is disposed such that the surface-shaped layer is provided on the far side from the lighting fixture. According to the general industrial standard (JIS-C8152 (2007 edition)), the evaluation by the integrating sphere type light transmittance measuring apparatus was carried out. The total light beam when the film was not inserted was regarded as 1, and the measured 値 (%) after the insertion of the film was evaluated. -34- 201142367 Table 1 Implementation Implementation Implementation Implementation Implementation Implementation Implementation Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Case 7 Example 8 Example 9 Structure Figure 1 Figure 2 Figure 3 4Fig. 2, Fig. 7, Fig. 1 Fig. 1 Fig. 1 Average particle size 2 2 2 2 2 2 2 0.5 3.5 Inner particle portion contains a scattering amount [parts] of the shot layer (relative to 101 101 101 101 101 101 11 25 101 100 parts of adhesive) Concealability [%] 93 93 93 93 93 93 90 93 93 Light use efficiency [Ή 88 87 87 90 87 88 89 87 87 -35- 201142367 Table 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Composition 1 Fig. 1 Fig. 5 Fig. 6 Fig. 6 Within the average particle diameter [βτη] 0.3 6.5 2 2 2 5.2 Partial particle content dispersion [part] Shot ( For 100 20 101 101 101 2 27 Layer adhesive) Concealability [%] 92 93 93 93 10 91 Light use efficiency [%] 80 84 85 81 90 . 85 From the results of Table 1, the results of Examples 1 to 9 can be judged. The light-diffusing film for LED illumination has a large concealing property and a small decrease in light use efficiency. On the other hand, it can be judged that the average particle diameter of the particles contained in the internal scattering layer is 0.3 // m, and the average particle diameter is In Comparative Example 2 of 6.5 // m and Comparative Example 6 having an average particle diameter of 5.2 μm, when the light diffusing film was designed to have substantially the same concealing property, the light use efficiency was lowered. Further, in the case of two substrates In Comparative Example 3 in which the internal scattering layer is not provided or Comparative Example 4 in which the surface shape layer is not provided, it is considered that the light use efficiency is lowered even when the design is designed such that the concealability is substantially the same. In addition, even if the type of the substrate is changed, the structure that satisfies the present invention can achieve both high concealability and light use efficiency. On the other hand, the light diffusion sheet of Japanese Patent No. 3993980 (Comp. -36-201142367 Example 5), Its system is designed to be able to vote from The back surface of the projection of an image projected by the projector is small, it can not completely eliminate the lamp images. <About Rigidity> As a performance index of rigidity, the elastic modulus (ns K7 171) is usually or bent. In the case of the strain, the amount of the strain is usually inversely proportional to the third power of the film thickness. When the strain is reduced to 1 / 8. As a result, the amount of strain can be greatly reduced. Refer to the specification of Japanese Application No. 20 1 0-79876. All the documents and the contents described in the present specification are borrowed in the same manner as the specific and individual descriptions with reference to the respective documents and patent applications. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing an example of the LED of the present invention. Fig. 2 is a schematic cross-sectional view showing an example of the LED of the present invention. Fig. 3 is a schematic cross-sectional view showing an example of the LED of the present invention. The opposition side is viewed from the transmissive screen from the transmissive screen's is the diffusion of the Yangge modulus UIS K7161). In the review, it is important to bend the thickness of the film. Therefore, the film thickness is doubled by bonding to make the film thickness. Thickening, revealing the content as a whole, breaking into the patent application, and breaking into the technical specifications and technical specifications, which are incorporated by reference into the other light of the light diffusing film of the light diffusing film Others of the diffusing film - 37 - 201142367 Fig. 4 is a schematic cross-sectional view showing another example of the light diffusing film for LED lighting of the present invention. Fig. 5 is a schematic cross-sectional view showing the layer structure of the comparative film 3 in the embodiment. Fig. 6 is a schematic cross-sectional view showing the layer structure of the comparative film 4 in the embodiment. Fig. 7 is a schematic cross-sectional view showing the layer structure of the film 6 in the embodiment. Fig. 8 is a view showing the evaluation method of the concealability of the image of the lamp in the embodiment, for explaining the average 値 of the brightness and the average 値 of the brightness. · [Main component symbol description] 10,12 base plate 14, 16 inner diffusing layer 18 adhesive layer 20 surface shape layer 22 low refractive index layer -38-