200848345 九、發明說明： 【發明所屬之技術領域】 本發明係有關用來保持並導引撓性帶狀支撐體（下稱 「薄片」（web))的薄片導引滾輪，該支撐體沿一預定進給 路徑連續進給，保持薄片於其圓筒形外周，並有關薄片導 引裝置及導引薄片之方法。 【先前技術】 最近，隨著液晶顯示器之市場擴張，對用於液晶顯示 器中偏光板之保護膜的纖維素三乙酸酯薄膜（下稱「TAC薄 膜」）的需要增加。因此，對溶劑流鑄（solution casting)設 備進行很多嘗試，以提高TAC薄膜之生產率。 於溶劑流鑄設備中，將連續流鑄於諸如流鑄帶等之支 支承上作爲原料的漿液溶劑自支承剝離。爲提高TAC薄膜 之生產率，須加快薄片的進給速度，並減小薄片的厚度。 惟，薄片進給速度的加快會導致以下問題。許多用來 沿進給方向保持並導引薄片的薄片導引滾輪隔一既定間隔 設在溶劑流鑄設備中。當薄片藉諸薄片導引滾輪導引時， 空氣有被吸入薄片與導引滾輪間的傾向。藉由加快薄片進 給速度，增加所吸入空氣量。 另一方面，因減少薄片厚度而降低薄片之剛性，且縐 紋容易形成於薄片上。因此，須減少施加於所進給薄片之 拉力。若減少進給薄片時的拉力，吸入薄片與導引滾輪間 的空氣量即增加。 當吸入薄片與薄片導引滾輪間的空氣量因加快薄片進 200848345 給速度及減少薄片厚度而增加時，薄片與薄片導引滾輪間 的接觸變得不穩，以致於諸如抓痕及拉伸縐紋的缺陷發生 於薄片上。 爲解決以上問題，於日本專利早期公開案第08- 1 7 5 72 7 及1 0 - 7 7 1 4 6號所揭示之運送滾輪中，溝槽及突起形成於運 送滾輪之周面上，以釋放吸入薄片與突起間進入溝槽的空 氣。此外，於日本轉利早期公開案第2003 - 1 465 05號所揭 示之薄片導引滾輪中，諸如玻璃珠之微細物體噴在滾輪之 周面上，以形成微細平坦或平滑部及凹部於滾輪之周面 上。將吸入薄片的空氣釋入凹部內，俾其可抑制薄片表面 上抓痕、表面轉印及縐紋的發生。 惟，日本專利早期公開案第08 - 1 75 72 7及1 0-77 1 46號 所揭示之運送滾輪用來於其塗布功能性材料之前’運送乾 膜薄片，亦即塑膠片及紙。因此，運送滾輪具有較高薄片 保持力量，惟當薄片在鑄以或塗以功能性材料之後立刻進 給時，可能會發生薄片上的表面轉印。 同時，於日本轉利早期公開案第2 0 0 3 - 1 4 6 5 0 5號所揭 示之滾輪中有薄片保持力量依薄片進給速度改變的傾向。 因此，當薄片進給速度加快時，吸入薄片中的空氣無法充 分釋入凹部，以致薄片於薄片導引滾輪上滑動。 本發明之一目的在於提供薄片導引滾輪、薄片進給裝 置及用來導引薄片之方法。薄片導引滾輪可保持並導引薄 片，不會造成於薄片上諸如抓痕、拉伸縐紋、表面轉印及 200848345 縐紋的缺陷，即使薄片進給速度加快時，且薄片厚度減少 時，仍不會受薄片進給速度影，亦維持薄片保持力量於恆 定水平。 【發明內容】 根據本發明，薄片導引滾輪設有一大致圓筒形滾輪本 體，其具有一外周，於該外周上形成複數周邊溝槽及微細 凹陷。周邊溝槽沿滾輪本體之外周的周向形成，並具有至 少〇.〇〇5mm及至多lmm的寬度。沿滾輪本體之軸向之周邊 溝槽間的節距至少爲〇 . 1 mm且至多2mm。微細凹陷形成於 相鄰周邊溝槽間，並相互連接。 根據一較佳實施例，周邊溝槽之寬度至少爲0.1mm且 至多0 · 5 mm。另一方面，微細凹陷之平均深度至少爲〇 . 0 0 5 mm且至多0.05mm。爲形成微細凹陷，將具有至少爲0.2mm 且至多1 mm大小的微細物體噴在滾輪本體之外周上。 y 較佳地，薄片導引滾輪放置於薄片進給裝置中，該薄 片進給裝置具有一用來供應帶狀薄片之供應源，並保持又 進給薄片。 根據本發明，由於在進給薄片時吸入薄片導引滾輪之 空氣透過周邊溝槽及微細凹陷釋放，因此，即使薄片進給 S度加速或者當薄片厚度減小時，薄片導引滾輪仍可確實 保持並導引薄片，不會因薄片之滑動而於薄片上形成縐 紋°此外’可藉由調整周邊溝槽之寬度和深度以及微細凹 200848345 陷之尺寸，避免薄片導引滾輪所進給薄片上諸如抓痕、拉 伸縐紋及表面轉印的缺陷。 【實施方式】 此後，詳細說明本發明之較佳實施例。惟，本發明不 限於其中所說明之實施例。 於圖1中，在一溶劑流鑄設備10中，一含有聚合物 1 1及溶劑1 2的塗料1 3自一澆鑄用模1 5流鑄於一澆鑄用 鑄帶1 4，以形成一澆鑄薄膜1 6於澆鑄用鑄帶1 4上。澆鑄 薄膜16藉來自一設於澆鑄用鑄帶14上方之烘乾導管17之 烘乾空氣烘乾，接著，溶劑氣體自澆鑄薄膜1 6蒸發。當澆 鑄薄膜1 6獲得自保持特性時，澆鑄薄膜1 6自澆鑄用鑄帶 1 4剝離成一濕薄膜20，並進給至一拉幅機2 1。將濕薄膜 20烘乾，並藉拉幅機21沿其寬度方向拉伸，以獲得一薄 膜22。將來自拉幅機21之薄膜22進給至一烘乾裝置23， 並烘乾。接著，藉一捲繞機24捲繞自烘乾裝置23排出的 薄膜。 . 所製成薄膜22係醋化程度58.0%至62.5%之纖維素酯 薄膜，並具有至少〇.3m及至多3m的寬度，至少2//m及 至多200//m的寬度，以及〇.5nm或更大的表面粗糙度。 如圖2所示，用來導引一連續進給之連續薄膜30(下稱 「薄片」（web))之多數薄片導引滾輪31設在烘乾裝置23 中。薄片導引滾輪31由一用來保持並導引薄片30之滾輪 本體3 2，以及裝配於滾輪本體3 2二端之軸3 3構成。滾輪 200848345 本體32藉由應用多種處理（參考圖3A至3E)於一鋁製圓筒 本體35(下稱「粗管」，參考圖3)形成，以提供穩定的薄 片進給能力。滾輪本體不限於由鋁製成，可由諸如鐵、不 銹鋼或碳纖維強化強化塑膠（CFRP)製成。 將以下處理方法應用於滾輪本體3 2。如圖3 A所示’ 一具有預定厚度的鎳鍍層3 6形成於粗管3 5之外周上。接 著，如圖3B所示，使用平均粒直徑〇.2mm至1 mm的玻璃 珠（未圖示），將噴吹處理應用於鎳鍍層3 6的表面。藉由噴 吹處理，於鎳鍍層3 6中形成具有大致半圓形之複數個向上 凸緣40及向下凹陷41。大多數向下凹陷41相互重疊，且 各重疊部形成一互連通道。 除了鎳以外，可使用鐵、銅等電鍍於管3 5。此外，於 噴吹處理中可使用諸如矽砂及陶珠之微小物體來替代玻璃 珠。此外，向下凹陷可不僅具有大致半球形’亦可具有大 致多角錐形。 其次，如於圖3 C中所示，藉由習知溝槽形成方法，隔 預定節距，沿粗管3 5之周向形成複數溝槽42。於本實施 例中，雖然諸溝槽42之每一者係底部爲大致橢圓形橫截面 之三角形溝槽，惟其可具有大致半圓形橫截面。 在形成諸圓周溝槽42之後，如於圖3 D中所示，將具 有預定厚度的鉻鍍鍍覆於具有諸向上凸緣40、諸向下凹陷 4 1及諸圓周溝槽42之鎳鍍層3 6的表面上。藉此，形成一 鉻鍍層44於鎳鍍層36上。此後，如於圖3E中所示，拋光 200848345 鉻鍍層4 4之表面以移除鉻鑛層4 4中對應向上凸緣4 0的某 些部分，俾諸平滑部46形成在異於向下凹陷41及諸圓周 溝槽4 2的部分。藉由使用摩擦布或紙、軟皮革等來進行拋 光處理。替代鉻鍍，可使用一硬質材料，藉陶瓷噴吹處理 等，鍍覆於鎳鍍層之表面上。 進行如圖3 Α至3 Ε所示種種處理來提供以下條件。如 於圖4中所示，向下凹陷41之平均深度D1至少爲0.005mm 及至多0.5mm。若平均深度D1小於0.00 5mm，僅釋放少量 " 於進給薄片時業已吸入之空氣，並降低薄片保持力量。同 時，若平均深度D 1大於0.0 5 mm，即難以形成凹陷。更糟 地，凹陷面積隨著深度增加變大，結果，表面轉印發生於 進給之薄片上。 同時，諸圓周溝槽42之深度D2爲至少0.005mm及至 多1mm，且諸圓周溝槽42間之節距P爲至少0.1mm及至 多2mm。由於深度D2設定爲至少0.00 5mm，因此，釋放 足夠量之進給薄片時吸入的空氣量’且以適當的保持力量 保持薄片3 0。因此，諸如縐紋之缺點不會發生於薄片上。 換言之，若深度D 2大於1 m m，處理即非所望地變得 困難。 諸圓周溝槽 42之寬度 D3爲至少 0.1mm及至多 0.5mm。由於寬度D3設定爲至多〇· 5mm，因此，即使待進 給之薄片很薄，仍不會於薄片3 0上發生諸如表面轉印及纖 紋之缺點。同時，若寬度D 3小於〇 · 1 mm，即變得難以製造 -10- 200848345 薄片導引滾輪3 1。藉由調整平滑部46之面積佔有率， 控制對薄片30之保持力量。於本實施例中，平滑部46 面積佔有率可至少〇 %及小於1 0 0 %，較佳地實際値爲 至 7 0 %。 當滿足此等條件時，相較於習知滾輪，薄片導引滾 3 1獲得以下有利效果。例如，於習知滾輪中，僅設有向 凹陷4 1之滾輪顯示有進給速度依存性，且當薄片3 0之 給速度加快時，無法釋放足夠之進給薄片時吸入之空氣 因此，降低對薄片3 0的保持力量。相較於此，本發 之薄片導引滾輪3 1甚至在薄片3 0之進給速度加快時， 可透過圓周溝槽42，釋放僅藉向下凹陷41所無法釋出 夠量的空氣。因此，無論薄片進給速度之加快情形如何 仍可維持薄片導引滾輪3 1之薄片保持力量恆定。藉此， 給薄片3 0而不會在薄片導引滾輪3 1上滑動。 於圖5中，一圖表5 0顯示相對於薄片3 0之進給速 之本發明薄片導引滾輪3 1的薄片保持力。同時，一圖 5 1顯示相對於薄片3 0之進給速度之僅具有向下凹陷之 輪（下稱「習知薄片導引滾輪」）的薄片保持力。其中， 發明之薄片導引滾輪3 1及習知薄片導引滾輪具有相同 平滑部的面積佔有率。如圖表5 0及5 1所示，當薄片3 0 進給速度低時（例如，進給速度S)，薄片導引滾輪31之 片保持力與習知薄片導引滾輪大約相同。當薄片3 0之進 速度加快時，習知薄片導引滾輪之薄片保持力迅速降低 可 之 40 击A m 下 進 〇 明 仍 足 進 度 表 滾 本 之 之 薄 給 -11- 200848345 惟薄片導引滾輪3 1之薄片保持力保持於一恆定値而未降 低。因此，經確認於本發明之薄片導引滾輪3 1上無薄片保 持力之速度依存性，且甚至當高速進給薄片30時，薄片 30仍可藉薄片導引滾輪31確實保持並導引。 於本實施例中，雖然說明設於溶劑流鑄設備之烘乾裝 置中之薄片導引滾輪，惟亦可應用本發明於設在諸如拉幅 機之其他設備之薄片導引滾輪。本發明可應用於不僅設在 溶劑流鑄設備，且設在其他製造設備的薄片導引滾輪。 於本實施例中’雖然使用連續纖維素乙酸酯作爲薄片， 惟可使用一可撓帶狀材料或帶狀物體，其使用該撓帶 狀材料作爲基礎材料，並於其表面上具有一工作層撓帶狀 材料由：諸如聚對苯二甲二乙酯、聚乙烯-2、6 -萘酯、聚 氯乙烯、聚偏二氯乙烯、聚碳酸酯、聚亞醯胺、聚醯胺等 塑膠膜；紙；塗布或層疊具有2至10個碳數，諸如聚乙烯、 聚丙烯及乙烯-丁烯聚合物之α -聚烯的紙；以及諸如鋁、 I 銅及錫之金屬箔製成。 〔實驗例〕 藉一實驗例澄清本實施例中薄片導引滾輪之效力。於 本實驗例中’決定薄片導引滾輪之構造及進給薄片之條件 如下： 1 )將具有1 〇 〇 μ m厚度之鎳鍍鍍覆於一粗管的外周，該 粗管由具有薄片導引滾輪3 1之1 〇 c m外徑規格之鋁製圓筒 本體形成。此後，使用具有800// m至900#m平均粒直徑 -12- 200848345 之玻璃珠，對該鍍鎳表面進行噴吹處理’俾形成複數個呈 大致半球形之向下凹陷。接者’於粗管之外周上’沿其周 向形成複數個底部係大致橢圓形橫截面之三角形溝槽。將 具有40 // m厚度之鉻鑛鍍覆於具有向下凹陷及溝槽之表面 以精加工外周。此後，藉一軟皮革拋光鉻鍍表面，俾在異 於向下凹陷及溝槽之位置形成平滑部。藉由該等一系列處 理，形成圖4所示向下凹陷41、圓周溝槽42及平滑部46。 將向下凹陷41之平均深度D1設定爲0.007mm(2.5 mm測 定距離之Rz値），並分別將圓周溝槽42之深度D2及節距 P分別設定爲至多〇.005 mm及至少1 mm，以及至少· 0.1 mm及至多2mm。同時，將平滑部46於滾輪本體32之表 面積中的面積佔有率設定爲50%。 2) 使用具有40 // m厚度之纖維素乙酸酯作爲薄片。 3) 就薄片處理條件而g，將薄片張力設定爲34kg/m， 將薄片捲繞角度設定爲3 0 ’將薄片進給速度設定爲至 少 20m/min 及至多 400m/min。 當藉薄片導引滾輪進給薄片時，觀察並評估如上述製 備之薄片導引滾輪之進給能力（薄片之表面品質）。首先， 當圓周溝槽之深度D 2小於〇 . 〇 〇 5 m m時，無法充分釋放於 進給薄片時吸入之空氣，且薄片滑動於薄片導引滾輪上。 另一方面’藉由比較該實驗例之薄片導引滾輪與習知 技術之向下凹陷滾輪，評估滾輪之薄片保持力之速度依存 性。結果，當薄片進給速度達到至少100m/min或更大時， -13- 200848345 向下凹陷滾輪之薄片保持力幾乎喪失，惟經確認，於本發 明之薄片導引滾輪中，無薄片保持力之速度依存性，甚至 於高速進給時，仍充分保持薄片。 雖然業已參考附圖，以較佳實施例充份說明本發明， 惟熟於本領域人士當知種種變化及變更。因此，除非此等 變化及變更悖離本發明之範圍，否則，其等均應解釋爲包 含在其中。 【圖式簡單說明】 4 本發明之以上及其他課題及優點由以下配合附圖所作 較佳實施例之詳細說明即可瞭然，惟，該說明僅供解說， 因此，不限制本發明。於圖式中，相同參考號碼標示若干 視圖中的相同或對應部分，其中： 圖1係溶劑流鑄設備之示意圖； 圖2係設於溶劑流鑄設備之一烘乾裝置中之一薄片導 引滾輪的立體圖； ( 圖3 A至3 E係顯示製造薄片導引滾輪之方法的部分橫 剖視圖； 圖4係圖2中所示薄片導引滾輪之外周之部分橫剖視 圖；以及 圖5係於本發明之薄片導引滾輪及僅具有向下凹陷之 薄片導引滾輪中之薄片保持力對薄片進給速度的圖表。 【主要元件符號說明】 10 溶劑流鑄設備 -14- 200848345 11 聚合物 12 溶劑 14 澆鑄用鑄帶 15 澆鑄用模 16 澆鑄薄膜 17 烘乾導管 20 濕薄膜 2 1 拉幅機 22 薄膜 23 烘乾裝置 24 捲繞機 30 連續薄膜 3 1 帶狀薄膜導引滾輪 32 滾輪本體 33 軸 3 5 圓筒本體（粗管） 36 鎳鍍層 40 向上凸緣 4 1 向下凹陷 42 周邊溝槽 44 鉻鍍層 46 平滑部 -15-200848345 IX. Description of the Invention: [Technical Field] The present invention relates to a sheet guiding roller for holding and guiding a flexible belt-shaped support body (hereinafter referred to as "web"), the support body is along a The predetermined feed path is continuously fed, maintaining the sheet on its cylindrical outer circumference, and relating to the sheet guiding device and the method of guiding the sheet. [Prior Art] Recently, as the market for liquid crystal displays has expanded, the demand for a cellulose triacetate film (hereinafter referred to as "TAC film") for a protective film for a polarizing plate in a liquid crystal display has increased. Therefore, many attempts have been made on solvent casting equipment to increase the productivity of TAC films. In a solvent casting apparatus, a slurry solvent continuously cast on a support such as a cast belt or the like as a raw material is peeled off from the support. In order to increase the productivity of the TAC film, it is necessary to speed up the feed rate of the sheet and reduce the thickness of the sheet. However, the accelerated feed rate of the sheet causes the following problems. A plurality of sheet guide rollers for holding and guiding the sheets in the feed direction are disposed at a predetermined interval in the solvent casting apparatus. When the sheet is guided by the sheet guiding roller, the air has a tendency to be sucked between the sheet and the guiding roller. The amount of air taken in is increased by increasing the feed rate of the sheet. On the other hand, the rigidity of the sheet is lowered by reducing the thickness of the sheet, and the crepe is easily formed on the sheet. Therefore, the pulling force applied to the fed sheet must be reduced. If the pulling force at the time of feeding the sheet is reduced, the amount of air between the suction sheet and the guide roller is increased. When the amount of air between the suction sheet and the sheet guiding roller is increased by increasing the speed of the sheet into the 200848345 and reducing the thickness of the sheet, the contact between the sheet and the sheet guiding roller becomes unstable, such as scratches and stretching. The defect of the grain occurs on the sheet. In order to solve the above problems, in the transport roller disclosed in Japanese Patent Laid-Open Publication No. 08-157 7 72 and No. 10-7 7 14 6 , grooves and protrusions are formed on the circumferential surface of the transport roller to The air that enters the groove between the suction sheet and the protrusion is released. In the sheet guiding roller disclosed in Japanese Laid-Open Patent Publication No. 2003-1 465 05, a fine object such as a glass bead is sprayed on the circumferential surface of the roller to form a fine flat or smooth portion and a concave portion on the roller. On the circumference. The air sucked into the sheet is released into the concave portion, which suppresses the occurrence of scratches, surface transfer, and crepe on the surface of the sheet. The transport rollers disclosed in Japanese Laid-Open Patent Publication No. 08-1775-72 and No. 10-77 1 46 are used to transport dry film sheets, i.e., plastic sheets and paper, before they are coated with functional materials. Therefore, the transport roller has a higher sheet holding force, but surface transfer on the sheet may occur when the sheet is fed immediately after casting or coating the functional material. At the same time, in the roller disclosed in Japanese Patent Laid-Open Publication No. 2 0 0 - 3 4 5 5 5 5, there is a tendency that the sheet holding force changes depending on the sheet feeding speed. Therefore, when the sheet feeding speed is increased, the air sucked into the sheet cannot be sufficiently released into the concave portion, so that the sheet slides on the sheet guiding roller. SUMMARY OF THE INVENTION One object of the present invention is to provide a sheet guiding roller, a sheet feeding device and a method for guiding the sheet. The sheet guiding roller can hold and guide the sheet without causing defects such as scratches, stretch crepe, surface transfer and 200848345 crepe on the sheet, even when the sheet feeding speed is increased and the sheet thickness is reduced, It is still not affected by the feed speed of the sheet, and the sheet is maintained at a constant level. SUMMARY OF THE INVENTION According to the present invention, a sheet guiding roller is provided with a substantially cylindrical roller body having an outer circumference on which a plurality of peripheral grooves and fine depressions are formed. The peripheral groove is formed along the circumference of the outer circumference of the roller body and has a width of at least 5 mm and at most 1 mm. The pitch between the grooves along the axial direction of the roller body is at least 〇 1 mm and at most 2 mm. Fine depressions are formed between adjacent peripheral grooves and connected to each other. According to a preferred embodiment, the width of the peripheral groove is at least 0.1 mm and at most 0. 5 mm. On the other hand, the fine depressions have an average depth of at least 〇0.5 mm and at most 0.05 mm. In order to form a fine recess, fine objects having a size of at least 0.2 mm and at most 1 mm are sprayed on the outer circumference of the roller body. y Preferably, the sheet guiding roller is placed in the sheet feeding device, the sheet feeding device having a supply source for supplying the strip sheet and holding the sheet feeding again. According to the present invention, since the air sucked into the sheet guiding roller is released through the peripheral groove and the fine recess when the sheet is fed, the sheet guiding roller can be surely maintained even if the sheet feeding speed is accelerated or when the sheet thickness is decreased. And guiding the sheet without forming a crepe on the sheet due to the sliding of the sheet. Further, by adjusting the width and depth of the peripheral groove and the size of the fine recess 200848345, the sheet guiding roller can be prevented from feeding on the sheet. Defects such as scratches, stretch crepe, and surface transfer. [Embodiment] Hereinafter, preferred embodiments of the present invention will be described in detail. However, the invention is not limited to the embodiments described therein. In Fig. 1, in a solvent casting apparatus 10, a coating material 13 containing a polymer 11 and a solvent 12 is cast from a casting mold 15 to a casting casting belt 14 to form a casting. The film 16 is applied to the casting belt 14 for casting. The cast film 16 is dried by dry air from a drying duct 17 provided above the casting cast strip 14, and then the solvent gas is evaporated from the cast film 16 . When the cast film 16 is self-sustaining, the cast film 16 is peeled off from the cast strip 14 into a wet film 20 and fed to a tenter 2 1 . The wet film 20 is dried and stretched in the width direction by a tenter 21 to obtain a film 22. The film 22 from the tenter 21 is fed to a drying device 23 and dried. Next, the film discharged from the drying device 23 is wound by a winder 24. The film 22 is a cellulose ester film having a degree of vinegarization of 58.0% to 62.5%, and has a width of at least 〇3m and at most 3m, a width of at least 2//m and at most 200//m, and 〇. Surface roughness of 5 nm or more. As shown in Fig. 2, a plurality of sheet guiding rollers 31 for guiding a continuous feeding continuous film 30 (hereinafter referred to as "web") are provided in the drying device 23. The sheet guide roller 31 is composed of a roller body 32 for holding and guiding the sheet 30, and a shaft 3 3 attached to both ends of the roller body 32. Roller 200848345 The body 32 is formed by applying a variety of processes (refer to Figs. 3A to 3E) to an aluminum cylinder body 35 (hereinafter referred to as "thick tube", see Fig. 3) to provide stable sheet feeding capability. The roller body is not limited to being made of aluminum and may be made of, for example, iron, stainless steel or carbon fiber reinforced plastic (CFRP). The following processing method is applied to the roller body 3 2 . As shown in Fig. 3A, a nickel plating layer 36 having a predetermined thickness is formed on the outer circumference of the thick tube 35. Next, as shown in Fig. 3B, a blowing treatment was applied to the surface of the nickel plating layer 36 using glass beads (not shown) having an average particle diameter of 22 mm to 1 mm. A plurality of upward flanges 40 and downward depressions 41 having a substantially semicircular shape are formed in the nickel plating layer 36 by a blowing process. Most of the downward recesses 41 overlap each other, and the overlapping portions form an interconnecting passage. In addition to nickel, it can be plated on the tube 35 using iron, copper, or the like. In addition, small objects such as enamel and ceramic beads can be used in the blowing process instead of glass beads. Further, the downward depression may have not only a substantially hemispherical shape but also a substantially polygonal pyramid shape. Next, as shown in Fig. 3C, a plurality of grooves 42 are formed along the circumferential direction of the thick tube 35 by a predetermined groove forming method by a conventional groove forming method. In the present embodiment, although each of the grooves 42 is a triangular groove having a substantially elliptical cross section, it may have a substantially semicircular cross section. After the circumferential grooves 42 are formed, as shown in FIG. 3D, chrome plating having a predetermined thickness is plated on the nickel plating having the upward flanges 40, the downward depressions 41, and the circumferential grooves 42. 3 6 on the surface. Thereby, a chrome plating layer 44 is formed on the nickel plating layer 36. Thereafter, as shown in FIG. 3E, the surface of the 200848345 chrome plating layer 4 is polished to remove portions of the chrome ore layer 44 corresponding to the upward flange 40, and the smooth portions 46 are formed to be different from the downward depression. 41 and portions of circumferential grooves 4 2 . The polishing treatment is performed by using a rubbing cloth or paper, soft leather, or the like. Instead of chrome plating, a hard material may be applied to the surface of the nickel plating by ceramic spraying or the like. Various processes as shown in Figs. 3 Α to 3 进行 are performed to provide the following conditions. As shown in Fig. 4, the downward depth 41 has an average depth D1 of at least 0.005 mm and at most 0.5 mm. If the average depth D1 is less than 0.005 mm, only a small amount of air that has been inhaled when feeding the sheet is released, and the sheet retains strength. At the same time, if the average depth D 1 is larger than 0.0 5 mm, it is difficult to form a depression. Worse, the recessed area becomes larger as the depth increases, and as a result, the surface transfer occurs on the fed sheet. At the same time, the circumferential grooves 42 have a depth D2 of at least 0.005 mm and at most 1 mm, and the pitch P between the circumferential grooves 42 is at least 0.1 mm and at most 2 mm. Since the depth D2 is set to at least 0.005 mm, the amount of air taken in when a sufficient amount of the feed sheet is released is released and the sheet 30 is held with an appropriate holding force. Therefore, disadvantages such as crepe do not occur on the sheet. In other words, if the depth D 2 is larger than 1 m m, the processing becomes undesirably difficult. The circumferential grooves 42 have a width D3 of at least 0.1 mm and at most 0.5 mm. Since the width D3 is set to at most 〇 5 mm, even if the sheet to be fed is thin, defects such as surface transfer and ridges do not occur on the sheet 30. Meanwhile, if the width D 3 is smaller than 〇 · 1 mm, it becomes difficult to manufacture -10- 200848345 sheet guiding roller 3 1 . The holding force against the sheet 30 is controlled by adjusting the area occupancy of the smoothing portion 46. In this embodiment, the smoothing portion 46 may have an area occupancy rate of at least 〇% and less than 100%, preferably 値 to 70%. When these conditions are satisfied, the sheet guiding roller 31 achieves the following advantageous effects as compared with the conventional roller. For example, in the conventional roller, only the feed speed dependence is displayed on the roller of the recess 41, and when the feed speed of the sheet 30 is increased, the air sucked in when the feed sheet cannot be sufficiently released is thus lowered. The holding force on the sheet 30. In contrast, the sheet guiding roller 3 1 of the present invention can transmit a sufficient amount of air which cannot be released by the downward recess 41 even when the feeding speed of the sheet 30 is increased. Therefore, the sheet holding force of the sheet guiding roller 3 1 can be maintained constant regardless of the acceleration of the sheet feeding speed. Thereby, the sheet 30 is given without sliding on the sheet guiding roller 31. In Fig. 5, a graph 50 shows the sheet holding force of the sheet guiding roller 3 1 of the present invention with respect to the feed speed of the sheet 30. Meanwhile, Fig. 51 shows the sheet holding force of only the downwardly recessed wheel (hereinafter referred to as "conventional sheet guiding roller") with respect to the feed speed of the sheet 30. Among them, the sheet guide roller 3 1 of the invention and the conventional sheet guide roller have an area occupying ratio of the same smooth portion. As shown in Figs. 50 and 51, when the feed speed of the sheet 30 is low (e.g., the feed speed S), the sheet holding force of the sheet guide roller 31 is about the same as that of the conventional sheet guide roller. When the advancement speed of the sheet 30 is accelerated, the sheet holding force of the conventional sheet guiding roller is rapidly lowered, and 40 hits the A m, and the sheet is still thin enough to give the sheet to the -11-200848345. The sheet holding force of 3 1 was maintained at a constant level without being lowered. Therefore, it is confirmed that there is no speed dependency of the sheet holding force on the sheet guiding roller 3 1 of the present invention, and even when the sheet 30 is fed at a high speed, the sheet 30 can be surely held and guided by the sheet guiding roller 31. In the present embodiment, although the sheet guiding roller provided in the drying device of the solvent casting apparatus is described, the present invention can be applied to a sheet guiding roller provided in other equipment such as a tenter. The present invention can be applied to a sheet guiding roller which is provided not only in a solvent casting apparatus but also in other manufacturing equipment. In the present embodiment, although continuous cellulose acetate is used as the sheet, only a flexible tape-like material or a belt-like object can be used, which uses the flexible tape-like material as a base material and has a work on the surface thereof. Layered strip material: such as: polyethylene terephthalate, polyethylene-2, 6-naphthyl ester, polyvinyl chloride, polyvinylidene chloride, polycarbonate, polyamidamine, polyamine, etc. Plastic film; paper; coated or laminated paper having 2 to 10 carbon numbers, such as polyethylene, polypropylene, and ethylene-butene polymer α-polyene; and metal foil such as aluminum, copper, and tin . [Experimental Example] The effectiveness of the sheet guiding roller in the present embodiment was clarified by an experimental example. In the present experimental example, the conditions for determining the structure of the sheet guiding roller and the feeding sheet are as follows: 1) Nickel plating having a thickness of 1 μm is plated on the outer circumference of a thick tube having a sheet guide The guide roller 3 1 is formed of an aluminum cylinder body having an outer diameter of 〇cm. Thereafter, the nickel-plated surface is subjected to a blowing treatment using a glass bead having an average particle diameter of from 2,000 to 200848345 of from 800 / / m to 900 # m to form a plurality of downward depressions which are substantially hemispherical. The picker 'on the outer circumference of the thick tube' forms a plurality of triangular grooves having a substantially elliptical cross section at the bottom along its circumference. A chrome ore having a thickness of 40 // m is plated on the surface having the downward depression and the groove to finish the outer circumference. Thereafter, the chrome-plated surface is polished by a soft leather, and the smooth portion is formed at a position different from the downward depression and the groove. By the series of processes, the downward recess 41, the circumferential groove 42, and the smooth portion 46 shown in Fig. 4 are formed. The average depth D1 of the downward recess 41 is set to 0.007 mm (Rz 2.5 of the measuring distance of 2.5 mm), and the depth D2 and the pitch P of the circumferential groove 42 are respectively set to at most 〇.005 mm and at least 1 mm, respectively. And at least · 0.1 mm and up to 2 mm. At the same time, the area occupation ratio of the smoothing portion 46 in the surface area of the roller body 32 is set to 50%. 2) A cellulose acetate having a thickness of 40 // m was used as a sheet. 3) With respect to the sheet processing conditions, g, the sheet tension was set to 34 kg/m, and the sheet winding angle was set to 3 0 ', and the sheet feeding speed was set to at least 20 m/min and at most 400 m/min. When the sheet was fed by the sheet guiding roller, the feeding ability (surface quality of the sheet) of the sheet guiding roller prepared as described above was observed and evaluated. First, when the depth D 2 of the circumferential groove is smaller than 〇 〇 〇 5 m m, the air sucked in when the sheet is fed is not sufficiently released, and the sheet slides on the sheet guiding roller. On the other hand, the speed dependence of the sheet holding force of the roller was evaluated by comparing the sheet guiding roller of the experimental example with the downwardly recessed roller of the prior art. As a result, when the sheet feeding speed reaches at least 100 m/min or more, the sheet holding force of the downwardly recessed roller is almost lost, but it is confirmed that there is no sheet holding force in the sheet guiding roller of the present invention. The speed dependence, even at high speeds, still maintains the foil. The present invention has been fully described by the preferred embodiments thereof with reference to the accompanying drawings. Therefore, unless such changes and modifications come within the scope of the invention, they are construed as being included. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects and advantages of the present invention will be understood from the following description of the preferred embodiments of the invention. In the drawings, the same reference numerals indicate the same or corresponding parts in several views, wherein: Figure 1 is a schematic diagram of a solvent casting apparatus; Figure 2 is a sheet guiding in a drying apparatus of a solvent casting apparatus Figure 3A to 3E show a partial cross-sectional view of a method of manufacturing a sheet guiding roller; Figure 4 is a partial cross-sectional view of the outer periphery of the sheet guiding roller shown in Figure 2; and Figure 5 is attached to the present A graph of the sheet guiding roller of the invention and the sheet holding force in the sheet guiding roller having only a downward depression to the sheet feeding speed. [Main component symbol description] 10 Solvent casting equipment-14- 200848345 11 Polymer 12 Solvent 14 Casting strip for casting 15 Casting mold 16 Casting film 17 Drying duct 20 Wet film 2 1 Tenter 22 Film 23 Drying device 24 Winder 30 Continuous film 3 1 Strip film guide roller 32 Roller body 33 Shaft 3 5 cylindrical body (thick tube) 36 nickel plating 40 upward flange 4 1 recessed downward 42 peripheral groove 44 chrome plating 46 smoothing portion -15-