JP2004114419A - Method and apparatus for manufacturing prism-like sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method capable of manufacturing a prism-like sheet excellent in product quality such as an aspect ratio, a uniform thickness or the like and requiring no complicated process, and a manufacturing apparatus therefor. <P>SOLUTION: A polymer solution is cast on a casting band 44 in a solution film forming apparatus 12 to form a sheet 52 and this sheet 52 peeled from the casting band 44 is fed through the nip between an embossing roller 54 having prism rows formed thereto and a backup roller 56 to transfer the prism rows to the surface on the side of a support of the sheet. Next, the embossed sheet is uniaxially stretched/dried in a non-contact state in a uniaxially stretching/non-contact drying device 16 and the stretched/dried sheet is passed through a contact type dryer and a contact type cooler and taken up by a take-up device to manufacture the prism-like sheet. <P>COPYRIGHT: (C)2004,JPO

Description

【００４３】
【表２】

【００４４】
製造されたプリズム様シートの評価方法としては、転写精度とシート厚みのバラツキの２項目で行った。転写精度は、エンボスローラのアスペクト比（Ｐ：Ｄ）とプリズム様シートのアスペクト比（Ｐ：Ｄ）が近い方が良いと評価した。転写形状実測方法は、キーエンス社製の超深度形状測定顕微鏡ＶＫ８５００を用いてプリズム列のうちの１０個の凸列のピッチ寸法と高さ寸法について測定し、平均値で表した。また、シート厚みのバラツキは、接触式厚み計を用いてプリズム様シートの幅方向厚み分布を測定して最大値と最小値の差をΔｄとし、Δｄが２μｍ未満であれば○（バラツキ小さい）、Δｄが２〜４μｍであれば△（バラツキ普通）、Δｄが４μｍ超えると×（バラツキ大きい）とした。
（実施例１）
本発明による実施例１では、エンボス時のシート搬送速度を３５ｍ／分、エンボスローラのローラ面温度を５°Ｃ、転写時におけるシートの残留揮発分を１．０、一軸延伸量を１．５倍、無接触乾燥の収縮量を０．７倍とした。その結果、プリズム様シートに形成されたプリズム列のピッチ寸法（Ｐ）１６μｍ、高さ寸法（Ｄ）８μｍで、アスペクト比（Ｐ：Ｄ）がエンボスローラと同じ２０：１０となった。また、シート厚みのバラツキも小さく○の評価であった。
（比較例１）
従来法による比較例１では、実施例１と同じ表１の高分子溶液で製造した８０μｍの乾膜シート（熱可塑性シート）に、表２のエンボスローラでプリズム列を熱転写した。エンボス時のシート搬送速度を３５ｍ／分、エンボスローラのローラ面温度を１４０°Ｃとした。その結果、プリズム様シートに形成されたプリズム列のピッチ寸法（Ｐ）２０μｍ、高さ寸法（Ｄ）６μｍで、アスペクト比（Ｐ：Ｄ）が２０：６となり、プリズム列の高さ方向の熱転写精度が悪かった。また、シート厚みのバラツキも大きく×の評価であった。
（比較例２）
比較例２では、熱転写精度を上げるために、エンボス時のシート搬送速度を１０ｍ／分まで遅くした。その結果、プリズム様シートに形成されたプリズム列のピッチ寸法２０μｍ、高さ寸法８μｍで、アスペクト比（Ｐ：Ｄ）が２０：８となり、比較例１に比べて改善されたが、実施例１よりも劣っていた。また、比較例２の場合、シート搬送速度を実施例１の１／３以下に遅くしなくてはならないので、生産効率の点で劣る。また、シート厚みのバラツキは△で普通の評価であった。
［Ｂ］試験Ｂは、本発明におけるエンボスローラ、バックアップロール、シートに関する好ましい温度条件を調べた。即ち、表１に示す組成の高分子溶液と表２に示すエンボスローラを用いて、図１の装置により平均厚みが８０μｍのプリズム様シートを製造したときに、エンボスローラのローラ面温度Ｔ_１、バックアップローラのローラ面温度Ｔ_２、転写時のシートの表面温度Ｔ_３が、転写精度、シート厚みのバラツキ、及びひげ状の剥離ムラの発生にどのように影響するかを調べた。
【００４５】
評価方法は、転写精度、シート厚みのバラツキについては試験Ａと同様であり、ひげ状の剥離ムラはシートを切断し、その断面を光学顕微鏡で観察（１００倍）することにより評価した。　　　　　　　　　　　　　　　　　　　　　　　（試験１）
試験１では、エンボス時のシート搬送速度を３５ｍ／分、エンボスローラのローラ面温度Ｔ_１（平均）を５°Ｃ、エンボスローラの幅方向のローラ面温度分布を２°Ｃ、バックアップローラのローラ面温度Ｔ_２（平均）を３°Ｃ、バックアップローラの幅方向のローラ面温度分布を２°Ｃ、転写時のシートの表面温度Ｔ_３（平均）を１５°Ｃ、転写時におけるシートの残留揮発分を１．０、一軸延伸量を１．５倍、無接触乾燥の収縮量を０．７倍とした。即ち、０°Ｃ≦Ｔ_３−Ｔ_１≦５０°Ｃ且つ０°Ｃ≦Ｔ_３−Ｔ_２≦５０°Ｃ、及び両ローラのローラ温度差と各ローラの温度分布の全てが本発明の好ましい条件を満足するようにした。その結果、プリズム様シートに形成されたプリズム列のピッチ寸法（Ｐ）１６μｍ、高さ寸法（Ｄ）８μｍで、アスペクト比（Ｐ：Ｄ）がエンボスローラと同じ２０：１０となり、ひげ状の剥離ムラもなかった。
（試験２）
試験２では、エンボス時のシート搬送速度を３５ｍ／分、エンボスローラのローラ面温度Ｔ_１（平均）を２０°Ｃ、エンボスローラの幅方向のローラ面温度分布を２°Ｃ、バックアップローラのローラ面温度Ｔ_２（平均）を２３°Ｃ、バックアップローラの幅方向のローラ面温度分布を２°Ｃ、転写時のシートの表面温度Ｔ_３（平均）を１５°Ｃ、転写時におけるシートの残留揮発分を１．０、一軸延伸量を１．５倍、無接触乾燥の収縮量を０．７倍とした。即ち、試験１との条件と比較したときに、０°Ｃ≦Ｔ_３−Ｔ_１≦５０°Ｃ且つ０°Ｃ≦Ｔ_３−Ｔ_２≦５０°Ｃを満足しない場合である。その結果、プリズム様シートに形成されたプリズム列のピッチ寸法（Ｐ）１６μｍ、高さ寸法（Ｄ）８μｍで、アスペクト比（Ｐ：Ｄ）がエンボスローラと同じ２０：１０となったが、シート厚みのバラツキも大きく×の評価であり、ひげ状の剥離ムラも観察された。
（試験３）
試験３では、エンボス時のシート搬送速度を３５ｍ／分、エンボスローラのローラ面温度Ｔ_１（平均）を５°Ｃ、エンボスローラの幅方向のローラ面温度分布を１１°Ｃ、バックアップローラのローラ面温度Ｔ_２（平均）を３°Ｃ、バックアップローラの幅方向のローラ面温度分布を２°Ｃ、転写時のシートの表面温度Ｔ_３（平均）を１５°Ｃ、転写時におけるシートの残留揮発分を１．０、一軸延伸量を１．５倍、無接触乾燥の収縮量を０．７倍とした。即ち、エンボスローラの幅方向のローラ面温度分布がローラ面平均温度より５°Ｃ以上になる場合である。その結果、プリズム様シートに形成されたプリズム列のピッチ寸法（Ｐ）１６μｍ、高さ寸法（Ｄ）８μｍで、アスペクト比（Ｐ：Ｄ）がエンボスローラと同じ２０：１０であり、ひげ状の剥離ムラもなかったが、シート厚みのバラツキが大きく×の評価であった。
（試験４）
試験４では、エンボス時のシート搬送速度を３５ｍ／分、エンボスローラのローラ面温度Ｔ_１（平均）を５°Ｃ、エンボスローラの幅方向のローラ面温度分布を２°Ｃ、バックアップローラのローラ面温度Ｔ_２（平均）を３°Ｃ、バックアップローラの幅方向のローラ面温度分布を９°Ｃ、転写時のシートの表面温度Ｔ_３（平均）を１５°Ｃ、転写時におけるシートの残留揮発分を１．０、一軸延伸量を１．５倍、無接触乾燥の収縮量を０．７倍とした。即ち、バックアップローラの幅方向のローラ面温度分布がローラ面平均温度より５°Ｃ以上になる場合である。その結果、プリズム様シートに形成されたプリズム列のピッチ寸法（Ｐ）１６μｍ、高さ寸法（Ｄ）８μｍで、アスペクト比（Ｐ：Ｄ）がエンボスローラと同じ２０：１０であり、ひげ状の剥離ムラもなかったが、シート厚みのバラツキが△の評価であった。
【００４６】
試験３と試験４を比較して分かることは、シート厚みのバラツキに対する影響は、バックアップローラのローラ面温度分布よりもエンボスローラのローラ面温度分布の方が大きく影響するということである。
［Ｃ］試験Ｃは、図１において重層流延として構成された装置を用い、固形分濃度の異なる２種類の高分子溶液を２層同時重層流延した場合と、１種類の高分子溶液を単層流延した場合に、同じ品質のプリズム様シートを得ることのできる製造速度を比較した。尚、単層流延の場合には、溶液製膜装置のドープ供給装置を１個とし、重層流延ダイを単層流延ダイに交換しただけで、その他の装置は図１と同じにした。また、使用した高分子溶液は、表４の高分子溶液Ａと表５の高分子溶液Ｂの２種類を使用した。シートへのプリズム列の転写は、使用したエンボスローラは表２と同じものを使用した。そして、シート乾燥後にシート厚みが８０μｍのプリズム様シートが得られるようにした。
【００４７】
【表３】

【００４８】
【表４】

【００４９】
製造されたプリズム様シートの評価方法は、試験［Ａ］、試験［Ｂ］と同様である。
（実施例２）
本発明による実施例２では、エンボス時のシート搬送速度を４５ｍ／分、エンボスローラのローラ面温度を２０°Ｃ、転写時におけるシートの残留揮発分を１．０、一軸延伸量を１．５倍、無接触乾燥の収縮量を０．７倍とした。また、２層同時重層流延条件として、支持体面側に表４の固形分濃度の高い高分子溶液を乾燥後で膜厚が６０μｍになるようにすると共に、反支持体面側に表３の固形分濃度の低い高分子溶液を乾燥後で膜厚が２０μｍになるようにした。即ち、シートの支持体面側の固形分濃度が反支持体面側の固形分濃度よりも相対的に高くなるようにし、固形分濃度の高い支持体面側に転写した。その結果、プリズム様シートに形成されたプリズム列のピッチ寸法（Ｐ）１６μｍ、高さ寸法（Ｄ）８μｍで、アスペクト比（Ｐ：Ｄ）がエンボスローラと同じ２：１になった。また、シート厚みのバラツキも小さく○の評価であった。
（比較例３）
比較例３では、エンボス時のシート搬送速度を３５ｍ／分、エンボスローラのローラ面温度を２０°Ｃ、転写時におけるシートの残留揮発分を１．０、一軸延伸量を１．５倍、無接触乾燥の収縮量を０．７倍とした。また、比較例３では重層流延せずに表４の高分子溶液を乾燥後の膜厚で８０μｍになるようにした。その結果、プリズム様シートに形成されたプリズム列のピッチ寸法（Ｐ）１６μｍ、高さ寸法（Ｄ）８μｍで、アスペクト比（Ｐ：Ｄ）がエンボスローラと同じ２：１になった。また、シート厚みのバラツキも小さく○の評価であった。
（比較例４）
比較例４では、比較例３におけるエンボス時のシート搬送速度を４５ｍ／分に速度を速めた以外は、比較例３と同じ条件で行った。その結果、プリズム様シートに形成されたプリズム列のピッチ寸法（Ｐ）１６μｍ、高さ寸法（Ｄ）６μｍで、アスペクト比（Ｐ：Ｄ）が２：０．７５になりエンボスローラのアスペクト比（Ｐ：Ｄ）２：１よりも高さ寸法（Ｄ）の転写率が悪くなった。また、シート厚みのバラツキが△の評価であった。
【００５０】
以上の試験結果から分かるように、実施例２の重層流延によって、比較例３の単層流延と同じ品質のプリズム様シートを製造する場合、エンボス時のシート搬送速度を約１．３倍速くすることができ、それだけ製造速度を上げることができる。また、比較例３と４との対比から分かるように、単層流延の場合には、エンボス時のシート搬送速度を実施例２と同じ速度まで速くすると、製造されるプリズム様シートの品質が低下する。
【図面の簡単な説明】
【図１】本発明のプリズム様シートの製造装置の全体構成図
【図２】重層流延ダイの一例を示す模式図
【図３】重層流延ダイの別の態様を示す模式図
【図４】重層流延ダイの更に別の態様を示す模式図
【図５】転写装置に設けられるエンボスローラのプリズム列を説明する断面図
【図６】エンボスローラのプリズム列をシートに転写している状態図
【図７】エンボスローラに形成されるプリズム列の形状を説明する説明図
【図８】一軸延伸・無接触乾燥装置を説明する説明図
【図９】溶液製膜装置の支持体の別態様として流延ドラムを説明する説明図
【図１０】プリズム様シートに形成されたプリズム列を説明する説明図
【符号の説明】
１０…プリズム様シートの製造装置、１２…溶液製膜装置、１４…転写装置、１６…一軸延伸・無接触乾燥装置、１８…裁断機、２０…ローレット装置、２２…接触式乾燥装置、２４…接触式冷却装置、２６…巻取装置、４２…流延ダイ、４４…流延バンド、５２…シート、５４…エンボスローラ、５４Ａ…凸列、５４Ｂ…プリズム列、５６…バックアップローラ、７８…流延ドラム[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a prism-like sheet manufacturing method and apparatus, and more particularly, to a prism-like sheet manufacturing method and apparatus used for expanding the viewing angle of a liquid crystal display device.
[0002]
[Prior art]
In the liquid crystal display device, since the liquid crystal itself has angle dependency, the viewing angle at which good display quality can be obtained is narrow, and the brightness of the display is reversed or the luminance is extremely decreased or increased depending on the viewing angle. Therefore, conventionally, in order to increase the viewing angle of the liquid crystal display device, a prism-like sheet 3 having prism rows 2 in which convex rows 1 having triangular cross sections as shown in FIG. ing.
[0003]
As a conventional method for producing a prism-like sheet, one of a pair of nip rollers composed of an emboss roller having a prism array formed on the roller surface and a backup roller having a smooth surface is used as a heat roller, and the nip roller is used for drying. There is a method in which the shape of the prism row of the embossing roller is thermally transferred to the thermoplastic sheet by nipping the thermoplastic sheet in a film state.
[0004]
As a method for producing a prism-like sheet not based on transfer, for example, in Patent Document 1, a laminate of a thermoplastic solution casting film, an adhesive material layer, and a uniaxially stretched film is heated at a temperature equal to or higher than the boiling point of the solvent. There is a method of peeling a uniaxially stretched film from a laminate after forming fine irregularities in a solution casting film by thermally shrinking the uniaxially stretched film.
[0005]
[Patent Document 1]
JP-A-11-221854
[0006]
[Problems to be solved by the invention]
However, the method of transferring the prism row of the embossing roller to the thermoplastic sheet by heat has a drawback in that the transfer accuracy is deteriorated because there is a limit in transferring fine irregularities. For example, when the nip force is released, the recesses between the protrusions tend to return to the original due to the elasticity of the thermoplastic sheet, so the height of the prism array becomes lower than the design dimension, and the design There is a drawback that a prism array having an aspect ratio close to the value cannot be formed. Further, since a large nip force is required, a large apparatus rigidity is required to manufacture a prism-like sheet having a uniform thickness, resulting in an increase in apparatus cost. In addition, since there is a limit to the improvement of the apparatus rigidity, there is a drawback that it is impossible to obtain a sufficient accuracy of the prism-like sheet thickness.
[0007]
Further, the method of Patent Document 1 has a drawback that the process is complicated because there is a process of laminating or peeling an adhesive layer or a uniaxially stretched film on a solution casting film.
[0008]
The present invention has been made in view of such circumstances, and a prism-like sheet manufacturing method and apparatus that can manufacture prism-like sheets excellent in product quality such as aspect ratio and uniform thickness and that do not require complicated processes. The purpose is to provide.
[0009]
[Means for solving the problems]
In order to achieve the above object, the present invention provides a method for producing a prism-like sheet having prism rows on a sheet surface, in which a polymer solution is cast on a traveling or rotating support to form a sheet. After the film is peeled off from the support, the sheet is nipped between a transfer member having a prism array formed on the transfer surface and the support member, and the transfer surface is transferred to the support surface side of the sheet surface. The method includes a transfer step of transferring the shape of the prism row of the member, and a drying step of drying the sheet on which the prism row is transferred.
[0010]
In order to achieve the above object, the present invention provides a solution for producing a sheet by casting a polymer solution on a traveling or rotating support in a prism-like sheet producing apparatus having a prism array on a sheet surface. After separating the sheet from the support, the sheet is nipped between the transfer member having the shape of the prism array formed on the transfer surface and the support member, and the sheet surface is supported on the support surface side of the sheet surface. And a transfer device that transfers the shape of the prism row of the transfer member, and a drying device that dries the sheet onto which the shape of the prism row is transferred.
[0011]
According to the present invention, a polymer solution is cast on a support to form a sheet, the sheet peeled from the support is nipped between the transfer member and the support member, and the transfer member is placed on the support surface side of the sheet surface. The shape of the prism row is transferred. A part of the volatile components such as a solvent contained in the sheet (hereinafter, simply referred to as “volatile component”) is volatilized on the support in the solution casting process, but the sheet immediately after being peeled off from the support is still remaining. It is in a wet soft film state with a large amount of volatile matter and almost no elasticity.
[0012]
In particular, the concentration of the residual volatile component of the sheet peeled from the support is higher on the support surface side than on the anti-support surface side, and the amount of the soft film is so much that the transfer accuracy to the support surface side is improved. Thereby, in the transfer process, the shape of the prism row formed on the transfer surface of the transfer member can be accurately transferred to the sheet surface. At this time, since a large nip force like the thermal transfer of the dry film thermoplastic sheet is not required, it is possible to prevent the roller from being bent by the nip force and the thickness of the sheet from becoming uneven. As the transfer member used here, a plate mold in which the shape of the prism row is formed can be used, and a flat support member can be arranged facing the plate mold, but from the viewpoint of complete continuation of production. It is preferable to use a pair of nip rollers including an embossing roller having a prism row shape formed on the roll surface and a backup roller facing the embossing roller.
[0013]
The sheet to which the shape of the prism row is transferred is then dried in a drying step. In the drying step, the volatile matter in the sheet is evaporated and dried, and a prism-like sheet is manufactured in which the prism row transferred to the surface is fixed. In this case, it is easier to form a good prism array when the sheet shrinks due to drying when the prism array is transferred to the support surface side having a large residual volatile content.
[0014]
Furthermore, since the sheet shrinks due to this drying, the pitch dimension, which is the distance between the apexes of the convex rows in the prism row, can be made smaller than that at the time of transfer. At this time, both the contraction in the pitch direction and the contraction in the height direction of the prism array occur, so that a prism array having a pitch dimension and a height dimension close to the designed aspect ratio can be obtained. In this way, in the drying process, the pitch dimension and height dimension of the prism array are smaller than those at the time of transfer. Therefore, the pitch dimension and height dimension of the prism array formed on the transfer member are manufactured in consideration of this. It is preferable that the pitch dimension and the height dimension of the prism rows formed on the prism-like sheet be larger. Measure the shrinkage rate that shrinks by drying in advance to determine the magnification of the pitch dimension and height dimension of the prism array formed on the transfer member relative to the pitch dimension and height dimension of the prism array formed on the sheet. Therefore, the magnification for absorbing the shrinkage rate may be used.
[0015]
In order to achieve the above object, the present invention provides a method for producing a prism-like sheet having a prism array on a sheet surface, wherein a plurality of polymer solutions are cast on a running or rotating support to form a sheet. In addition to film formation, the solid content concentration of the plurality of polymer solutions is adjusted so that the solid content concentration on the support surface side of the sheet is relatively higher than the solid content concentration on the anti-support surface side. After the solution is formed, and after the sheet is peeled off from the support, the sheet is nipped between the transfer member having a prism array formed on the transfer surface and the support member, and the sheet surface is placed on the support surface side. The method includes a transfer step of transferring the shape of the prism row of the transfer member, and a drying step of drying the sheet on which the prism row is transferred.
[0016]
In order to achieve the above object, the present invention provides a prism-like sheet manufacturing apparatus having a prism array on a sheet surface, in which a plurality of polymer solutions are cast on a running or rotating support to form a sheet. In addition to film formation, the solid content concentration of the plurality of polymer solutions is adjusted so that the solid content concentration on the support surface side of the sheet is relatively higher than the solid content concentration on the anti-support surface side. After the sheet is peeled from the support, the sheet is nipped between the transfer member having the shape of the prism array formed on the transfer surface and the support member, and the sheet surface is supported on the support surface side. A transfer device in which the transfer member and the support member are arranged so that the shape of the prism row of the transfer member is transferred; and a drying device for drying the sheet on which the shape of the prism row is transferred. Features .
[0017]
According to the present invention, as described above, the sheet immediately after being peeled off from the support is still in a wet soft film state with a large amount of residual volatile matter and hardly has elasticity, and is formed on the transfer surface of the transfer member in the transfer process. The shape of the prism array thus formed can be accurately transferred to the sheet surface. Furthermore, in the present invention, the solid content concentration of the plurality of polymer solutions is adjusted to form a film so that the solid content concentration on the support surface side of the sheet is relatively higher than the solid content concentration on the anti-support surface side. did.
[0018]
That is, when the casting speed is increased in order to increase the productivity, the turbulence of the flow increases when the polymer solution (dope) passes through the die slit. In this case, since the support surface side of the sheet is in contact with the support, the unevenness on the surface of the sheet is flattened even if there is a disturbance in the flow described above. However, unevenness remains on the side of the surface opposite to the support, which is a surface in contact with air, and even when the surface of the transfer member is flat during transfer, transfer is poor due to the unevenness. This transfer failure can be improved by lowering the polymer concentration (dope concentration) in the polymer solution, but in order to increase the casting speed, the self-supporting property must be improved and the polymer average contained in the sheet It is necessary to increase the concentration. Therefore, a condition in which the transfer accuracy and the casting speed contradict each other is required. However, as in the present invention, the solid content concentration of the plurality of polymer solutions is adjusted so that the solid content concentration on the support surface side of the sheet is relatively higher than the solid content concentration on the anti-support surface side. By doing so, it has been found that both of these conflicting can be achieved.
[0019]
According to the aspect of the present invention, it is preferable to manage the residual volatile content as an index of the soft film state, and the residual volatile content of the sheet at the time of transfer is 0.3 to 3.0 when the solid content of the sheet is 1. It is preferable that it is the range of these. If the residual volatile content is less than 0.3, the sheet is too hard, the transfer accuracy is deteriorated, and a large nip force is required for transfer. On the other hand, if the residual volatile content exceeds 3.0, the sheet is too soft and transfer accuracy is deteriorated.
[0020]
According to the aspect of the present invention, in the transfer step, the transfer surface temperature of the transfer member is set to T ₁ , The support surface temperature of the support member is T ₂ , T is the surface temperature of the sheet during transfer ₃ When the temperature is 0 ° C ≦ T ₃ -T ₁ ≦ 50 ° C and 0 ° C ≦ T ₃ -T ₂ It is preferable that ≦ 50 ° C. is satisfied. Thereby, whisker-like peeling unevenness that tends to occur at the corners of the prism row can be eliminated, and contamination of the transfer surface of the transfer member can be prevented.
[0021]
According to the aspect of the present invention, in the drying step, the sheet is subjected to contactless drying until the residual volatile content of the sheet becomes 0.1 or less when the solid content of the sheet is 1, and the contactless drying is performed. It is preferable to set the drying conditions so that the sheet area after shrinkage at the outlet is 0.5 to 0.9 when the sheet area before shrinkage at the entrance of contactless drying is set to 1. . For example, a shrinkage amount of 0.5 means that it has become half of that before contactless drying. This is because when the residual volatile content of the sheet exceeds 0.1, the shape of the prism array transferred to the sheet is not completely solidified. This is because there is a risk of deformation. Further, if the contraction amount of the sheet is less than 0.5 and the contraction amount is excessively large, it is not preferable that the sheet surface tends to have a wrinkle different from the prism row. Further, if the contraction amount of the sheet exceeds 0.9, the effect of reducing the pitch of the prism rows by drying cannot be sufficiently obtained.
[0022]
According to the aspect of the present invention, it is preferable to have a stretching step of uniaxially stretching the sheet, onto which the shape of the prism row is transferred, in a direction along the prism row between the transfer step and the drying step. For example, if a prism row is formed in the sheet conveyance direction and the sheet is uniaxially stretched in the direction along the prism row, the width direction of the sheet contracts, so that the pitch of the prism row can be further reduced. . In this case, it is preferable to uniaxially stretch the sheet 1.1 to 3.0 times in the direction along the prism row. If the amount of uniaxial stretching is less than 1.1 times, the effect of reducing the pitch of the prism rows by uniaxial stretching cannot be obtained. On the other hand, if it exceeds 3.0 times, not only the sheet may be broken, but also the widthwise dimension of the sheet will not be constant in the sheet conveying direction, so the parallelism between the convex rows of the prism row is impaired.
[0023]
According to the aspect of the present invention, it is preferable that the transfer member is an embossing roller having a prism row formed on the roll surface, and the support member is a backup roller having a smooth roll surface.
[0024]
According to an aspect of the present invention, a casting die for performing multi-layer casting with a solution casting apparatus is a feed block die system including a feed block in which a plurality of polymer solutions are merged at the inlet of a single layer die, or a plurality of A multi-manifold die system in which a plurality of polymer solutions are joined inside the manifold having a manifold is preferable.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a preferred embodiment of a method and apparatus for manufacturing a prism-like sheet according to the present invention will be described in detail with reference to the accompanying drawings.
[0026]
FIG. 1 is an overall configuration diagram of a prism-like sheet manufacturing apparatus 10 according to the present invention. Mainly, a solution film forming apparatus 12, a transfer apparatus 14, a uniaxial stretching / non-contact drying apparatus 16, an ear cutting machine 18, and a knurling apparatus. 20, a contact-type drying device 22, a contact-type cooling device 24, and a winding device 26. In FIG. 1, the solution casting apparatus 12 is shown as an example in which a plurality of dope supply devices 13 are provided so that a plurality of polymer solutions (dope) can be cast in multiple layers. Uses one dope supply device 13.
[0027]
As shown in FIG. 1, in the dope supply device 13 of the solution casting apparatus 12, a predetermined amount of polymer stored in the mixing tank 28 and a predetermined amount of solvent stored in the solvent tank 30 are respectively determined by a metering pump 32, 34 is sent to the static mixer 36 where it is mixed and dissolved to prepare a polymer solution (dope). In this case, the temperature at which the polymer and the solvent are mixed is preferably in the range of −10 ° C. to 55 ° C., and is usually carried out at room temperature. The ratio of the polymer to the solvent is determined by the concentration of the finally obtained polymer solution, but in general, the polymer amount is preferably 5 to 30% by weight of the polymer solution to be prepared, and 8 to 25 More preferably, it is 10% by weight, most preferably 10% by weight. Further, additives necessary for the polymer may be added. The prepared polymer solution is sent to the casting die 42 by the liquid feeding pipe 40 through the continuous filtration device 38. Since the configuration of another dope supply device 13 is the same as described above, only the “dope supply device” is shown in FIG. In the preparation of this polymer solution, in the case of multi-layer casting, the polymer solution prepared by each of the dope supply devices 13 and 13 is changed by changing the polymer amount or the solvent amount when the polymer is dissolved in the solvent. The solid content concentration of the polymer solution cast on the support surface side (the surface in contact with the casting band 44) is adjusted to be higher than the solid content concentration of the polymer solution cast on the anti-support surface side. Try to be relatively high. Then, in the case of single layer casting, it is sent to the casting die 42 for single layer, and in the case of multilayer casting, it is sent to the casting die 42 for multilayer.
[0028]
As shown in FIG. 2, the multilayer casting die 42 has a joining portion 84 where two polymer solution flow paths 83 and 83 join at the inlet 82 of a single-layer die 81 having one manifold 80. As shown in FIG. 3, the feed block die system for connecting the feed block 85 or two manifolds 80, 80, and two polymer solutions supplied to the manifolds 80 are respectively connected to the flow paths 83, 83. A multi-manifold die system that joins to the joining portion 84 through can be suitably used. Furthermore, as shown in FIG. 4, two single-layer dies 81 each having one manifold 80 may be arranged side by side so as to be cast one after another. The multi-layer casting die in FIGS. 2 to 4 is shown as an example of two-layer casting. However, depending on the number of polymer solutions to be superposed, the number of flow paths of the feed block and the number of manifolds of the multi-manifold die Alternatively, the number of single-layer dies that are successively cast may be changed. Moreover, the code | symbol 44 of FIGS. 2-4 is a casting band.
[0029]
As shown in FIG. 1, a stainless steel casting band 44 is disposed below the casting die 42, and the casting band 44 is formed on the casting part side rotating drum 46 and the non-casting part side. The belt is wound around the rotating drum 48 and the casting band 44 circulates in the direction of arrow A between the casting portion side rotating drum 46 and the non-casting portion side rotating drum 48. Between the casting part side rotating drum 46 and the non-casting part side rotating drum 48, there are provided a plurality of support rollers 50 that support the casting band 44 so as not to loosen. The cast film of the polymer solution cast from the casting die 42 onto the casting band 44 is volatile (mainly solvent) in the casting film while the casting band 44 travels around once. ) Is volatilized to form a thin sheet 52.
[0030]
Polymer types of polymer solutions used in solvent film formation include polyolefins (eg, norbornene polymers), polyamides (eg, aromatic polyamides), polysulfones, polyethers (polyethersulfones and polyethers). Ketones), polystyrenes, polycarbonates, polyacrylic acids, polyacrylamides, polymethacrylic acids (eg, polymethyl methacrylate), polymethacrylamides, polyvinyl alcohols, polyureas, polyesters, polyurethanes, polyimides , Polyvinyl acetates, polyvinyl acetals (eg, polyvinyl formal, polyvinyl butyral) and cellulose derivatives (eg, lower fatty acid ester of cellulose) are used. The present invention is particularly effective when a lower fatty acid ester of cellulose is used. The lower fatty acid of the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. The number of carbon atoms is preferably 2 (cellulose acetate), 3 (cellulose propionate), or 4 (cellulose butyrate). More preferred is cellulose acetate, and cellulose triacetate (degree of oxidation: 58.0 to 62.5%) is particularly preferred. A mixed fatty acid ester of cellulose such as cellulose acetate propionate or cellulose acetate butyrate may be used.
[0031]
As the solvent of the polymer solution used in the solvent film formation, the polymer is dissolved or swollen by the solvent at a temperature in the range of 0 ° C. to 55 ° C. (temperature that is planned when the polymer solution is used). Combinations of polymers and solvents can be used. Unless it is swollen by the polymer and the solvent, it is almost impossible to dissolve even by using a cooling dissolution method (see JP-A-9-95544). Although there are aqueous and solvent-based solvents, organic solvents can be preferably used. Examples of organic solvents include halogenated hydrocarbons (eg, methylene chloride), ketones (eg, acetone, methyl ethyl ketone, cyclohexanone), esters (eg, methyl formate, methyl acetate, ethyl acetate, amyl acetate, vinyl acetate). Acetyl acetate), ethers (eg, dioxane, dioxolane, THF, diethyl ether, methyl-t-butyl ether), hydrocarbons (eg, benzene, toluene, xylene, hexane), and alcohols (eg, methanol, ethanol) included. As described above, the solvent is a liquid that dissolves or swells the polymer. Therefore, it is preferable to select a specific type of solvent according to the type of polymer used. For example, when the polymer is cellulose triacetate, polycarbonates or polystyrenes, acetone or methyl acetate is used as a preferred solvent. In the case of a norbornene-based polymer, benzene, toluene, xylene, hexane, acetone, and methyl ethyl ketone are used as preferred solvents. When polymethyl methacrylate is a polymer, acetone, methyl ethyl ketone, methyl acetate, butyl acetate and methanol are used as preferred solvents. Two or more kinds of solvents may be mixed and used. The boiling point of the solvent is preferably 20 ° C to 300 ° C, and most preferably 40 ° C to 100 ° C.
[0032]
The sheet 52 formed by the solution casting apparatus 12 is peeled off from the casting band 44 by being sent to the transfer device 14 disposed in the vicinity of the casting portion side rotating drum 46, and the support surface of the sheet 52. The prism row is transferred to the side (the surface in contact with the casting band 44). The transfer device 14 includes a pair of nip rollers 54 and 56 each including an embossing roller 54 disposed on the support surface side of the sheet 52 and a backup roller 56 disposed on the side opposite to the support surface of the sheet 52. Is done. As shown in FIG. 5, in the circumferential direction of the roller surface of the embossing roller 54, the shape of a prism row 54 </ b> B in which annular convex rows 54 </ b> A (prisms) having a triangular cross section are formed substantially in parallel is formed. By carrying out nip conveyance with the roller 54 and the backup roller 56, the shape of the prism row along the sheet conveyance direction is transferred to the side surface of the support of the sheet surface as shown in FIG. As shown in FIG. 7, the prism row 54B formed on the embossing roller 54 is defined by a pitch dimension (P) and a height dimension (D), and varies depending on the specifications of the prism-like sheet as a product. The pitch dimension (P) is 5 to 100 μm and the height dimension (D) is 5 to 100 μm. However, in the case of the present invention, the sheet 52 is contracted by drying after transferring the prism row to the soft film-formed sheet 52 formed by solvent film formation. Is smaller than the size at the time of transfer. Therefore, considering the shrinkage during drying, the pitch dimension and height dimension of the prism array 54B formed on the embossing roller 54 are the pitch dimension and height dimension of the prism array formed on the manufactured prism-like sheet. It is preferable to make it larger. Specifically, the shrinkage ratio in the pitch direction and the shrinkage ratio in the height direction that shrink by drying are measured in advance, and the pitch dimension and height dimension of the prism row 54B formed on the embossing roller 54 are reduced. What is necessary is just to make it the magnification which absorbs a rate. In this case, a plurality of embossing rollers 54 having different prism row pitch dimensions and height dimensions are prepared, and the pitch and height dimensions of the prism rows formed on the prism-like sheet, drying conditions, and the sheet to be described later. It is good to use properly according to the change of the pitch dimension by uniaxial stretching. As a method of forming the prism row on the roller surface of the embossing roller 54, various known methods can be adopted depending on the material of the embossing roller 54 and the shape of the prism row 54B, such as photolithography, machining, electric discharge machining, and laser machining. .
[0033]
The transfer device 14 can also be provided with an embossing roller 54 and a backup roller 56 so that the prism row is transferred to the side of the sheet 52 opposite to the support. It is preferable that the prism row is transferred to the support surface side. This is because the concentration of the residual volatile content of the sheet 52 peeled from the casting band 44 is larger on the support surface side than on the anti-support surface side, and thus the support surface side is in a soft membrane state than the anti-support surface side. The side surface opposite to the support is harder than the side of the support surface. Therefore, not only the transfer accuracy is improved when transferred to the support surface side in the soft film state, but the sheet 52 can be stably supported when the anti-support surface side in the relatively hard film state is supported by the backup roller 56. Therefore, the transfer accuracy is further improved. Further, when the sheet is shrunk at the time of subsequent drying, a Prism row having a small pitch dimension is likely to be formed due to a shrinkage difference between the dura mated anti-support surface and the soft film surface. The residual volatile content of the sheet at the time of transfer is preferably in the range of 0.1 to 3.0, more preferably in the range of 0.3 to 2.0, where the solid content of the sheet 52 is 1. If the residual volatile content is less than 0.1, the sheet 52 is too hard, the transfer accuracy is deteriorated, and a large nip force is required for transfer. On the other hand, if the residual volatile content exceeds 3.0, the sheet 52 is too soft and transfer accuracy is deteriorated.
[0034]
In addition, in the case of multi-layer casting, the solid content concentration on the support surface side of the sheet 52 needs to be relatively higher than the solid content concentration on the anti-support surface side. This is because, in the polymer concentration in the dope and the sheet, a condition in which the transfer accuracy and the casting speed contradict each other is required, but as in the present invention, the solid content concentration on the support surface side of the sheet is set to the solid content on the anti-support surface side. This is because by adjusting the solid content concentration of the plurality of polymer solutions so as to be relatively higher than the partial concentration to form a film, both of these conflicting can be achieved. In the case of two-layer casting, the concentration ratio between the solid content concentration of the polymer solution cast on the support surface side and the solid content concentration of the polymer solution cast on the anti-support surface side is When the solid content concentration of the polymer solution is 1, the solid content concentration of the polymer solution on the support surface side is preferably in the range of 1.1 to 1.5 times.
[0035]
The transfer device 14 sets the roller surface temperature of the embossing roller 54 to T ₁ The roller surface temperature of the backup roller 56 is T ₂ The surface temperature of the sheet 52 during transfer is T ₃ It is preferable that the following formula (1) is satisfied.
[0036]
[Expression 1]
0 ° C ≦ T ₃ -T ₁ ≦ 50 ° C and 0 ° C ≦ T ₃ -T ₂ ≦ 50 ° C (1)
Thereby, when the transfer portion of the sheet 52 moves away from the embossing roller 54, whisker-like peeling unevenness that easily occurs at the corner portion of the prism row transferred to the sheet 52 can be prevented, and the roller surface of the embossing roller 54 due to peeling. Can prevent dirt. In this case, the roller surface temperature T of the embossing roller 54 ₁ And roller surface temperature T of the backup roller 56 ₂ (Hereinafter referred to as “roller temperature difference”) within 5 ° C., preferably within 2 ° C. Furthermore, the roller surface temperature distribution in the roller width direction of the embossing roller 54 and the roller surface temperature distribution in the roller width direction of the backup roller 56 are within ± 5 ° C., preferably ± 5 ° with respect to the average roller surface temperature in the transfer range. It is preferably within 2 ° C. In particular, if the roller surface temperature distribution in the roller width direction of the embossing roller 54 is large, the variation in the thickness in the width direction of the sheet 52 after transfer tends to increase. In order to obtain such temperature conditions, for example, a water passage pipe (not shown) is built in each of the embossing roller 54 and the backup roller 56, and the water passage pipes are respectively connected via a rotary joint (not shown). It connects with a heat carrier supply apparatus (not shown). Then, the temperature of the roller surfaces of the embossing roller 54 and the backup roller 56 is controlled by circulating the heat medium between the rollers 54 and 56. The method for obtaining the temperature condition is not limited to the medium circulation method.
[0037]
The sheet 52 on which the shape of the prism row is transferred by the transfer device 14 is sent to the uniaxial stretching / contactless drying device 16 and is uniaxially stretched in the conveying direction of the sheet 52, that is, the direction along the prism row. Non-contact drying of residual volatiles remaining in 52 is performed. FIG. 8 mainly shows the uniaxial stretching / non-contact drying apparatus 16, and the conveying method of the sheet 52 is reversed from that in FIG. As shown in FIG. 8, the uniaxial stretching / non-contact drying device 16 is divided into a uniaxial stretching zone 58 and a non-contact drying zone 60 in order from the transfer device 14 side. The uniaxial stretching zone 58 is covered with a casing 66 having a drying air supply port 62 and a discharge port 64, the transfer device 14 is disposed at the upstream end in the sheet conveying direction in the zone 58, and the downstream end passes through the non-contact drying zone 60. It is connected to the sheet conveyance inlet 69 of the casing 68 to be covered. In the non-contact drying zone 60, a plurality of drying air blowers 70 are disposed opposite to the upper side and the lower side of the sheet 52 along the conveying direction of the sheet 52 to be conveyed, and a conveying device 72 that conveys the sheet 52. Is provided. Then, the sheet 52 is dried from both the front surface and the back surface while the sheet 52 is supported in the air by the dry air blown from the dry air blower 72 disposed opposite to the sheet 52. The conveying device 72 may be any conveying system that supports both ends in the width direction of the sheet 52 to be cut in the subsequent process (hereinafter referred to as “sheet ears”) and does not contact the center of the sheet that is the product. A method and a clip tenter method can be used preferably. The pin tenter type conveying device 72 has a pair of moving chains 74 disposed at both ear side positions of the sheet 52, and a pin plate (not shown) in which a large number of pins are implanted is supported on the moving chain 74. Therefore, the sheet 52 is conveyed while being tensioned in the width direction by inserting the pin into the ear portion of the sheet 52. In the clip tenter system, the ears of the sheet 52 are supported by crimping instead of pins, and the basic transport mechanism is the same. The sheet 52 conveyed in the uniaxial stretching zone 58 is conveyed by applying a tension in the conveyance direction of the sheet 52 by making the conveyance speed of the sheet 52 by the conveyance device 72 faster than the nip conveyance speed by the transfer device 14. Uniaxially stretch in the direction. If the sheet 52 is uniaxially stretched in the conveyance direction, that is, the direction along the prism row, the width direction of the sheet 52 contracts, so that the pitch dimension of the prism row can be made smaller than that during transfer. In this case, the sheet 52 is preferably uniaxially stretched 1.1 to 3.0 times in the direction along the prism row, and more preferably 1.5 to 2.0 times. When the uniaxial stretching is less than 1.1 times and there is almost no effect of reducing the pitch dimension of the prism row by uniaxial stretching, when it exceeds 3.0 times, not only the sheet 52 may be broken but also the sheet width may be reduced. Since it is no longer constant in the transport direction, the parallelism between the prism rows is impaired. Therefore, it is necessary to set the relationship between the sheet conveyance speed of the conveyance device 72 and the nip conveyance speed of the transfer device 14 so that the sheet 52 can be uniaxially stretched 1.1 to 3.0 times.
[0038]
In the non-contact drying zone 60, the non-contact drying is performed until the residual volatile content of the sheet 52 becomes 0.1 or less when the solid content of the sheet 52 is 1, and the non-contact drying of the sheet 52 is performed. When the area of the sheet 52 before shrinkage at the entrance of the contactless drying zone 60 is 1 as the shrinkage amount, the sheet area at the exit is preferably 0.5 to 0.9, more preferably 0.7 to 0. It is preferable to set the drying conditions to be 8. This is because if the sheet 52 comes into contact with a device such as a guide roller in a subsequent process in a state where the residual volatile content is not less than 0.1, the shape of the prism row may be deformed. Further, if the contraction amount of the sheet 52 is too large such that the contraction amount of the sheet 52 is less than 0.5, it is not preferable that the sheet surface is likely to be wrinkled separately from the prism row. If the contraction amount of the sheet 52 exceeds 0.9, the effect of reducing the pitch of the prism rows by drying cannot be obtained.
[0039]
In the sheet 52 that has been uniaxially stretched and contactlessly dried by the uniaxial stretching / non-contact drying apparatus 16, the portion of the ear portion of the sheet 52 that is supported by pins or clips is cut by the cutting machine 18 (see FIG. 1). Cut in the transport direction. The cutter 18 may be a rotary blade type, a cutter blade type, or another type. Knurls having protrusions with a height of 5 to 50 μm are applied to the ears of the cut sheet 52 by a pair of knurling devices 20 disposed at both ear positions of the sheet. The sheet 52 that has been knurled by the knurling device 20 is dried by the contact-type drying device 22, cooled to room temperature by the contact-type cooling device 24, and taken up by the winding device 26. In this way, if knurling is applied to both ears of the sheet 52, the contact-type drying device 22 and the contact-type cooling device 24, as shown in FIG. Even if the support surface and the anti-support surface are in a roller arrangement in which the support surface alternately contacts the guide roller 76, the prism row can be prevented from being deformed when contacting the guide roller 76. Therefore, according to the height dimension of the prism row formed on the sheet 52, it is preferable that the height of the knurled protrusion be equal to or higher than the height of the prism row within a range of 5 to 50 μm. Further, if knurling is applied to both ears of the sheet 52, no winding deviation occurs when the sheet 52 is wound by the winding device 26, so that deformation of the prism row during winding can be suppressed.
[0040]
In the present embodiment, the example of the casting band 44 has been described as the support of the solution casting apparatus 12, but a casting drum 78 may be used as shown in FIG.
[0041]
【Example】
[A] Test A uses a polymer solution having the composition shown in Table 1 and an embossing roller shown in Table 2 to produce a prism-like sheet having an average thickness of 80 μm using the apparatus shown in FIG. A prism-like sheet having an average thickness of 80 μm was produced by the thermal transfer system described in the prior art, and the quality of the examples and comparative examples was evaluated.
[0042]
[Table 1]

[0043]
[Table 2]

[0044]
As an evaluation method of the manufactured prism-like sheet, two items of transfer accuracy and variation in sheet thickness were used. Regarding the transfer accuracy, it was evaluated that the aspect ratio (P: D) of the embossing roller and the aspect ratio (P: D) of the prism-like sheet were better. The method for measuring the transferred shape was measured with respect to the pitch dimension and height dimension of 10 convex rows of the prism row using an ultra-deep shape measuring microscope VK8500 manufactured by Keyence, and expressed as an average value. Further, the variation in sheet thickness is measured by measuring the thickness distribution in the width direction of the prism-like sheet using a contact-type thickness meter, and the difference between the maximum value and the minimum value is Δd. If Δd is less than 2 μm, ○ (small variation) When Δd is 2 to 4 μm, Δ (variation is normal), and when Δd exceeds 4 μm, x is large (variation is large).
Example 1
In Example 1 according to the present invention, the sheet conveyance speed during embossing is 35 m / min, the roller surface temperature of the embossing roller is 5 ° C., the residual volatile content of the sheet during transfer is 1.0, and the uniaxial stretching amount is 1.5. The shrinkage of non-contact drying was set to 0.7 times. As a result, the pitch dimension (P) of the prism row formed on the prism-like sheet was 16 μm, the height dimension (D) was 8 μm, and the aspect ratio (P: D) was 20:10, the same as that of the embossing roller. Moreover, the variation in sheet thickness was small and the evaluation was good.
(Comparative Example 1)
In Comparative Example 1 according to the conventional method, the prism row was thermally transferred to the 80 μm dry film sheet (thermoplastic sheet) produced from the same polymer solution as in Example 1 as in Example 1 using the embossing roller in Table 2. The sheet conveying speed during embossing was 35 m / min, and the roller surface temperature of the embossing roller was 140 ° C. As a result, the pitch dimension (P) of the prism row formed on the prism-like sheet is 20 μm, the height dimension (D) is 6 μm, and the aspect ratio (P: D) is 20: 6. The accuracy was bad. Further, the variation in sheet thickness was also evaluated as x.
(Comparative Example 2)
In Comparative Example 2, the sheet conveying speed during embossing was slowed down to 10 m / min in order to increase the thermal transfer accuracy. As a result, the prism row formed on the prism-like sheet had a pitch dimension of 20 μm and a height dimension of 8 μm, and the aspect ratio (P: D) was 20: 8, which was improved as compared with Comparative Example 1. Was inferior. Moreover, in the case of the comparative example 2, since the sheet conveyance speed has to be slowed down to 1/3 or less of the first embodiment, it is inferior in terms of production efficiency. Further, the sheet thickness variation was an ordinary evaluation with Δ.
[B] Test B examined preferred temperature conditions for the embossing roller, backup roll, and sheet in the present invention. That is, when a prism-like sheet having an average thickness of 80 μm is manufactured using the polymer solution having the composition shown in Table 1 and the embossing roller shown in Table 2, the roller surface temperature T of the embossing roller is as follows. ₁ The roller surface temperature T of the backup roller ₂ , Surface temperature T of the sheet during transfer ₃ Were examined how it affects transfer accuracy, sheet thickness variation, and the occurrence of whisker-like peeling unevenness.
[0045]
The evaluation method was the same as that in Test A with respect to the transfer accuracy and variation in sheet thickness, and the whisker-like peeling unevenness was evaluated by cutting the sheet and observing the cross section with an optical microscope (100 times). (Test 1)
In Test 1, the sheet conveyance speed during embossing is 35 m / min, and the roller surface temperature T of the embossing roller. ₁ (Average) is 5 ° C, the roller surface temperature distribution in the width direction of the embossing roller is 2 ° C, the roller surface temperature T of the backup roller ₂ (Average) is 3 ° C, the roller surface temperature distribution in the width direction of the backup roller is 2 ° C, and the surface temperature T of the sheet during transfer ₃ The (average) was 15 ° C., the residual volatile content of the sheet at the time of transfer was 1.0, the amount of uniaxial stretching was 1.5 times, and the shrinkage of contactless drying was 0.7 times. That is, 0 ° C ≦ T ₃ -T ₁ ≦ 50 ° C and 0 ° C ≦ T ₃ -T ₂ ≦ 50 ° C., and the roller temperature difference between the two rollers and the temperature distribution of each roller all satisfy the preferable conditions of the present invention. As a result, the pitch dimension (P) of the prism row formed on the prism-like sheet is 16 μm, the height dimension (D) is 8 μm, the aspect ratio (P: D) is 20:10, which is the same as that of the embossed roller, and the whisker-like peeling occurs. There was no unevenness.
(Test 2)
In Test 2, the sheet conveying speed during embossing is 35 m / min, and the roller surface temperature T of the embossing roller. ₁ (Average) is 20 ° C., Emboss roller width direction roller surface temperature distribution is 2 ° C., Backup roller roller surface temperature T ₂ (Average) is 23 ° C., the roller surface temperature distribution in the width direction of the backup roller is 2 ° C., and the surface temperature T of the sheet during transfer. ₃ The (average) was 15 ° C., the residual volatile content of the sheet at the time of transfer was 1.0, the amount of uniaxial stretching was 1.5 times, and the shrinkage of contactless drying was 0.7 times. That is, when compared with the conditions of Test 1, 0 ° C ≦ T ₃ -T ₁ ≦ 50 ° C and 0 ° C ≦ T ₃ -T ₂ ≦ 50 ° C. is not satisfied. As a result, the pitch dimension (P) of the prism row formed on the prism-like sheet was 16 μm, the height dimension (D) was 8 μm, and the aspect ratio (P: D) was 20:10, which was the same as that of the embossing roller. The variation in thickness was also evaluated as x, and a whisker-like peeling unevenness was also observed.
(Test 3)
In Test 3, the sheet conveying speed during embossing is 35 m / min, and the roller surface temperature T of the embossing roller. ₁ (Average) is 5 ° C, the roller surface temperature distribution in the width direction of the embossing roller is 11 ° C, the roller surface temperature T of the backup roller ₂ (Average) is 3 ° C, the roller surface temperature distribution in the width direction of the backup roller is 2 ° C, and the surface temperature T of the sheet during transfer ₃ The (average) was 15 ° C., the residual volatile content of the sheet at the time of transfer was 1.0, the amount of uniaxial stretching was 1.5 times, and the shrinkage of contactless drying was 0.7 times. That is, this is a case where the roller surface temperature distribution in the width direction of the embossing roller is 5 ° C. or more from the roller surface average temperature. As a result, the pitch (P) of the prism row formed on the prism-like sheet is 16 μm, the height (D) is 8 μm, and the aspect ratio (P: D) is 20:10, which is the same as that of the embossed roller. Although there was no peeling unevenness, the sheet thickness variation was large and the evaluation was x.
(Test 4)
In Test 4, the sheet conveyance speed during embossing is 35 m / min, and the roller surface temperature T of the embossing roller. ₁ (Average) is 5 ° C, the roller surface temperature distribution in the width direction of the embossing roller is 2 ° C, the roller surface temperature T of the backup roller ₂ (Average) is 3 ° C, the roller surface temperature distribution in the width direction of the backup roller is 9 ° C, and the surface temperature T of the sheet during transfer ₃ The (average) was 15 ° C., the residual volatile content of the sheet at the time of transfer was 1.0, the amount of uniaxial stretching was 1.5 times, and the shrinkage of contactless drying was 0.7 times. That is, this is a case where the roller surface temperature distribution in the width direction of the backup roller is 5 ° C. or more from the roller surface average temperature. As a result, the pitch (P) of the prism row formed on the prism-like sheet is 16 μm, the height (D) is 8 μm, and the aspect ratio (P: D) is 20:10, which is the same as that of the embossed roller. Although there was no peeling unevenness, the sheet thickness variation was evaluated as Δ.
[0046]
The comparison between Test 3 and Test 4 shows that the influence on the variation in sheet thickness is more affected by the roller surface temperature distribution of the embossing roller than the roller surface temperature distribution of the backup roller.
[C] Test C uses the apparatus configured as the multi-layer casting in FIG. 1, when two types of polymer solutions having different solid content concentrations are cast simultaneously in two layers, and one type of polymer solution is The production speed at which the same quality prism-like sheet can be obtained in the case of single layer casting was compared. In the case of single layer casting, only one dope supply device of the solution casting apparatus is used, and the multilayer casting die is replaced with a single layer casting die, and the other devices are the same as in FIG. . The polymer solution used was two types of polymer solution A in Table 4 and polymer solution B in Table 5. The transfer of the prism row onto the sheet was the same as the embossing roller used in Table 2. A prism-like sheet having a sheet thickness of 80 μm was obtained after the sheet was dried.
[0047]
[Table 3]

[0048]
[Table 4]

[0049]
The evaluation method of the manufactured prism-like sheet is the same as the test [A] and the test [B].
(Example 2)
In Example 2 according to the present invention, the sheet conveying speed during embossing is 45 m / min, the roller surface temperature of the embossing roller is 20 ° C., the residual volatile content of the sheet during transfer is 1.0, and the uniaxial stretching amount is 1.5. The shrinkage of non-contact drying was set to 0.7 times. Further, as the conditions for simultaneous two-layer casting, the polymer solution having a high solid content concentration in Table 4 is dried on the support surface side so that the film thickness becomes 60 μm after drying, and the solid solution in Table 3 is formed on the anti-support surface side. After drying the polymer solution having a low concentration, the film thickness was adjusted to 20 μm. That is, the solid content concentration on the support surface side of the sheet was relatively higher than the solid content concentration on the anti-support surface side, and transferred to the support surface side having a high solid content concentration. As a result, the pitch dimension (P) of the prism row formed on the prism-like sheet was 16 μm, the height dimension (D) was 8 μm, and the aspect ratio (P: D) was 2: 1, the same as that of the embossing roller. Moreover, the variation in sheet thickness was small and the evaluation was good.
(Comparative Example 3)
In Comparative Example 3, the sheet conveyance speed during embossing was 35 m / min, the roller surface temperature of the embossing roller was 20 ° C., the residual volatile content of the sheet during transfer was 1.0, the uniaxial stretching amount was 1.5 times, The shrinkage of contact drying was set to 0.7 times. In Comparative Example 3, the polymer solution shown in Table 4 was not dried and the film thickness after drying was adjusted to 80 μm. As a result, the pitch dimension (P) of the prism row formed on the prism-like sheet was 16 μm, the height dimension (D) was 8 μm, and the aspect ratio (P: D) was 2: 1, the same as that of the embossing roller. Moreover, the variation in sheet thickness was small and the evaluation was good.
(Comparative Example 4)
Comparative Example 4 was performed under the same conditions as Comparative Example 3, except that the sheet conveyance speed during embossing in Comparative Example 3 was increased to 45 m / min. As a result, the pitch dimension (P) of the prism row formed on the prism-like sheet is 16 μm, the height dimension (D) is 6 μm, the aspect ratio (P: D) is 2: 0.75, and the aspect ratio of the embossing roller ( P: D) The transfer rate of the height dimension (D) was worse than 2: 1. Further, the sheet thickness variation was evaluated as Δ.
[0050]
As can be seen from the above test results, when a prism-like sheet having the same quality as the single-layer casting of Comparative Example 3 is produced by the multi-layer casting of Example 2, the sheet conveying speed at the time of embossing is about 1.3 times faster. The production speed can be increased accordingly. Further, as can be seen from the comparison between Comparative Examples 3 and 4, in the case of single-layer casting, when the sheet conveying speed during embossing is increased to the same speed as in Example 2, the quality of the prism-like sheet produced is improved. descend.
[Brief description of the drawings]
FIG. 1 is an overall configuration diagram of a prism-like sheet manufacturing apparatus according to the present invention.
FIG. 2 is a schematic view showing an example of a multi-layer casting die.
FIG. 3 is a schematic view showing another embodiment of a multi-layer casting die.
FIG. 4 is a schematic view showing still another embodiment of a multi-layer casting die.
FIG. 5 is a cross-sectional view illustrating a prism row of embossing rollers provided in a transfer device
FIG. 6 is a state diagram in which a prism row of an emboss roller is transferred to a sheet.
FIG. 7 is an explanatory diagram for explaining the shape of a prism row formed on an embossing roller.
FIG. 8 is an explanatory diagram for explaining a uniaxial stretching / contactless drying apparatus.
FIG. 9 is an explanatory diagram for explaining a casting drum as another embodiment of the support of the solution casting apparatus.
FIG. 10 is an explanatory diagram illustrating prism rows formed on a prism-like sheet.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Manufacturing apparatus of prism-like sheet | seat, 12 ... Solution film forming apparatus, 14 ... Transfer apparatus, 16 ... Uniaxial stretching and non-contact drying apparatus, 18 ... Cutting machine, 20 ... Knurling apparatus, 22 ... Contact-type drying apparatus, 24 ... Contact cooling device, 26 ... winding device, 42 ... casting die, 44 ... casting band, 52 ... sheet, 54 ... embossing roller, 54A ... convex row, 54B ... prism row, 56 ... backup roller, 78 ... flow Drum

Claims (14)

In the method of manufacturing a prism-like sheet having prism rows on the sheet surface,
A solution casting step of casting a polymer solution on a traveling or rotating support to form a sheet; and
After the sheet is peeled off from the support, the sheet is nipped between the transfer member having the shape of the prism array formed on the transfer surface and the support member, and the prism array of the transfer member is formed on the support surface side of the sheet surface. A transfer process for transferring the shape of
A drying step of drying the sheet onto which the prism row is transferred;
A method for producing a prism-like sheet, comprising: In the method of manufacturing a prism-like sheet having prism rows on the sheet surface,
A plurality of polymer solutions are cast on a running or rotating support to form a sheet, and the solid content concentration on the support surface side of the sheet is relatively higher than the solid content concentration on the anti-support surface side. A solution casting step of forming a film by adjusting the solid content concentration of the plurality of polymer solutions so as to be higher;
After the sheet is peeled off from the support, the sheet is nipped between the transfer member having the shape of the prism array formed on the transfer surface and the support member, and the prism array of the transfer member is formed on the support surface side of the sheet surface. A transfer process for transferring the shape of
A drying step of drying the sheet onto which the prism row is transferred;
A method for producing a prism-like sheet, comprising: 3. The transfer process according to claim 1, wherein in the transfer step, a residual volatile content of the sheet at the time of transfer is in a range of 0.1 to 3.0 when the solid content of the sheet is 1. 3. Manufacturing method of prism-like sheet. In the transfer step, T ₁ the transfer surface temperature of the transfer _member, the support surface temperature of the support member T _2, the surface temperature of the sheet during transfer when the T _3, the temperature just before transfer,
The prism-like sheet according to claim 1, wherein 0 ° C ≦ T ₃ −T ₁ ≦ 50 ° C. and 0 ° C ≦ T ₃ −T ₂ ≦ 50 ° C. are satisfied. Manufacturing method. In the drying step, contactless drying is performed until the residual volatile content of the sheet becomes 0.1 or less when the solid content of the sheet is 1, and the shrinkage amount of the sheet due to contactless drying is The drying conditions are set so that the sheet area after shrinkage at the outlet becomes 0.5 to 0.9 when the sheet area before shrinkage at the entrance of non-contact drying is 1. 4. The method for producing a prism-like sheet according to any one of 4 above. 6. The method according to claim 1, further comprising a stretching step of uniaxially stretching the sheet, onto which the shape of the prism row is transferred, in a direction along the prism row between the transfer step and the drying step. A method for producing the prism-like sheet according to 1. In the said extending process, the said sheet | seat is uniaxially extended 1.1 to 3.0 times in the direction along the said prism row | line | column, The manufacture of the prism-like sheet | seat of any one of Claims 1-6 characterized by the above-mentioned. Method. In a prism-like sheet manufacturing apparatus having prism rows on the sheet surface,
A solution casting apparatus for producing a sheet by casting a polymer solution on a traveling or rotating support;
After the sheet is peeled from the support, the sheet is nipped between the transfer member having the shape of the prism array formed on the transfer surface and the support member, and the prism array of the transfer member is formed on the support surface side of the sheet surface. A transfer device for transferring
A drying device for drying the sheet onto which the shape of the prism row is transferred;
An apparatus for producing a prism-like sheet, comprising: In a prism-like sheet manufacturing apparatus having prism rows on the sheet surface,
A plurality of polymer solutions are cast on a running or rotating support to form a sheet, and the solid content concentration on the support surface side of the sheet is relatively higher than the solid content concentration on the anti-support surface side. A solution casting apparatus for forming a film by adjusting the solid content concentration of the plurality of polymer solutions so as to be higher;
After the sheet is peeled off from the support, the sheet is nipped between the transfer member having the shape of the prism array formed on the transfer surface and the support member, and the prism array of the transfer member is disposed on the support surface side of the sheet surface. A transfer device in which the transfer member and the support member are arranged so that the shape of
A drying device for drying the sheet onto which the shape of the prism row is transferred;
An apparatus for producing a prism-like sheet, comprising: 10. The stretching device for uniaxially stretching a sheet, onto which the shape of the prism row is transferred, in a direction along the prism row, is provided between the transfer device and the drying device. Prism-like sheet manufacturing equipment. 11. The transfer member according to claim 8, wherein the transfer member is an embossing roller having a shape of the prism row formed on a roll surface, and the support member is a backup roller having a smooth roll surface. Prism-like sheet manufacturing equipment. 12. The pitch dimension and height dimension of the prism row formed on the transfer member are larger than the pitch dimension and height dimension of the prism row formed on the manufactured prism-like sheet. The prism-like sheet manufacturing apparatus according to any one of the above. The casting die for performing multi-layer casting with the solution casting apparatus includes a feed block die system having a feed block in which a plurality of polymer solutions are merged at an inlet of a single layer die, or a plurality of manifolds, and the manifold The prism-like sheet manufacturing apparatus according to claim 9, wherein the apparatus is of a multi-manifold die type in which a plurality of polymer solutions are merged inside. The prism-like die according to claim 9, wherein the casting die for performing the multi-layer casting by the solution casting apparatus is a single-layer die arrangement system in which a plurality of single-layer dies are arranged and the multi-layer casting is sequentially performed. Sheet manufacturing equipment.

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