JP4190876B2 - Dryer canvas for paper machines - Google Patents

Description

上記より求めたズレ角度θ１，θ２から、カンバス走行時の織組織のズレを推定し、カンバスの走行安定性の評価に用いる。
【００６２】
４．「有効ニュートラルライン厚み」
図９はニュートラル位置Ｎｐの計算データを測定する装置１１０であって、緯糸方向幅寸法３５ｍｍ（紙面の表裏面方向の寸法）に調整した試料Ｓに対し、経糸方向に６．１ｋｇ（１．７４ｋｇ／ｃｍ）の荷重をかけ、経糸方向に約１５０ｍｍの試長を付し、直径寸法１００．９ｍｍのロール１１１に試長部がロール面に当たるように巻き付け、６．１ｋｇ（１．７４ｋｇ／ｃｍ）の荷重Ｗをかけた状態で、試料Ｓの外側表面に紙テープを張り付け、試料の試長マーク位置を紙テープにマーキングする。紙テープを剥がし直定規でマーキングの長さを測定する。
【００６３】
上記より求めた直線での試長の読みＬ（ｍｍ）、ロール１１１に巻き付けたときの試長の読みＬｒ（ｍｍ）、ロール１１１の直径寸法Ｄ（＝１００．９ｍｍ）、カンバスの厚みｔ（ｍｍ）より、次式でニュートラル位置Ｎｐ（カンバスの厚さを１としたときのカンバス外側からニュートラルラインまでの位置割合）が、次式（２）で計算される。
【００６４】
【式１】

【００６５】
接紙面側を外側に捲回して測定・算出したＮｐ（図１５の▲３▼に対応）をＰＳ_Np、反接紙面側を外側に捲回して測定・算出したＮｐ（図１５の▲１▼に対応）をＢＳ_Npとして、接紙面側を外側にした時の接紙面からニュートラルラインまでの厚さ寸法ｔ１、および反接紙面側を外側にしたときの接紙面からの厚さ寸法ｔ２を、次式（３）（４）で計算する。
ｔ１＝ＰＳ_Np×ｔ （３）
ｔ２＝（１−ＢＳ_Np）×ｔ （４）
【００６６】
前記厚さ寸法ｔ１およびｔ２の合計を有効ニュートラルライン厚みとして、シングルラン方式や、単列ドライヤー方式に掛け入れたカンバス２が湿紙４に及ぼす速度の変化程度を厚さとして評価する。この数値が小さいほど、湿紙４に及ぼす速度変化の影響は少ないと評価する。
【００６７】
５．「カンバスの接紙面の接触面積」
カンバスより試料を切り取り、この試料に感圧紙（富士写真フイルム社製）を乗せ、直径寸法５２ｍｍの接圧子を荷重４００ｄａＮで３０秒間圧接させて、接触点を発色させた。これをコピーし、この接触点の発色パターンコピーをスキャナーでパソコンに取り込み画像解析により、接触面積率（％）を求めた。接触面積率が大きいほど、カンバスの接紙面は平滑と評価する。
【００６８】
（実施例）
次に、本発明の実施例およびこの実施例に対する比較例について、表１〜表３に基づいて説明する。表１〜表３において、ＴＭはポリエステルモノフィラメント、ＰＳは接紙面側、ＢＳは反接紙面側を表す。
【００６９】
【表１】

【００７０】
（実施例１）
実施例１のドライヤーカンバスを、表１に示す仕様と図６（Ａ）に示す織組織に基づいて製作した。すなわち、経糸１１に寸法が厚さ０．３０ｍｍ×幅０．５６ｍｍの断面四角形ポリエステルモノフィラメント｛図１（Ａ）の断面形状｝、接紙面側の緯糸１２に寸法が厚さ０．３０ｍｍ×幅０．６５ｍｍの断面四角形ポリエステルモノフィラメント｛図２（Ａ）の断面形状｝、反接紙面側の緯糸１３に直径寸法が０．７０ｍｍの断面円形ポリエステルモノフィラメント｛図３（Ａ）の断面形状｝を用い、接紙面側が２／２破れ斜文、反接紙面側が３／１の破れ斜文の緯２重織組織で、接紙面側の経糸１１ａが長浮きした、経糸密度５４．４本／２．５４ｃｍ、緯糸密度１７．７本×２層／２．５４ｃｍに製作した。製作したドライヤーカンバスは、厚さ１．４９ｍｍ、通気度２，４００ｃｍ³／ｃｍ²・minであった。
【００７１】
（実施例２）
実施例２のドライヤーカンバスを、表１に示す仕様と図６（Ａ）に示す織組織に基づいて製作した。すなわち、経糸１１に寸法が厚さ０．３０ｍｍ×幅０．５６ｍｍの断面四角形ポリエステルモノフィラメント｛図１（Ａ）の断面形状｝、接紙面側の緯糸１２に寸法が厚さ０．３０ｍｍ×幅０．６５ｍｍの断面四角形ポリエステルモノフィラメント｛図２（Ａ）の断面形状｝、反接紙面側の緯糸１３に直径寸法が０．８０ｍｍの断面円形ポリエステルモノフィラメント｛図３（Ａ）の断面形状｝を用い、接紙面側が２／２破れ斜文、反接紙面側が３／１の破れ斜文の緯２重織組織で、接紙面側の経糸１１ａが長浮きした、経糸密度５４．２本／２．５４ｃｍ、緯密度１７．５本×２層／２．５４ｃｍに製作した。製作したドライヤーカンバスは、厚さ１．６０ｍｍ、通気度２，５００ｃｍ³／ｃｍ²・minであった。
【００７２】
【表２】

【００７３】
（比較例１）
比較例１のドライヤーカンバスを、表２に示す仕様と図６（Ａ）に示す織組織に基づいて製作した。すなわち、経糸に寸法が厚さ０．３０ｍｍ×幅０．５６ｍｍの断面四角形ポリエステルモノフィラメント｛図１（Ａ）の断面形状｝、接紙面側の緯糸１２および反接紙面側の緯糸１３に寸法が直径０．７０ｍｍの断面円形ポリエステルモノフィラメントを用い、接紙面側が２／２破れ斜文、反接紙面側が３／１の破れ斜文の緯２重織組織で、接紙面側の経糸が長浮きした、経糸密度５３．０本／２．５４ｃｍ、緯密度１７．９本×２層／２．５４ｃｍに製作した。製作したドライヤーカンバスは、厚さ１．７４ｍｍ、通気度３，０００ｃｍ³／ｃｍ²・minであった。
【００７４】
（比較例２）
比較例２のドライヤーカンバスを、表２に示す仕様と図６（Ａ）に示す織組織に基づいて製作した。すなわち、経糸に寸法が厚さ０．２５ｍｍ×幅０．６５ｍｍの断面四角形ポリエステルモノフィラメント｛図１（Ａ）の断面形状｝、接紙面側の緯糸１２および反接紙面側の緯糸１３に寸法が直径０．６０ｍｍの断面円形ポリエステルモノフィラメントを用い、接紙面側が２／２破れ斜文、反接紙面側が３／１の破れ斜文の緯２重織組織で、接紙面側の経糸が長浮きした、経糸密度４６．７本／２．５４ｃｍ、緯密度２０．１本×２層／２．５４ｃｍに製作した。製作したドライヤーカンバスは、厚さ１．３４ｍｍ、通気度１，９００ｃｍ³／ｃｍ²・minであった。
【００７５】
上記の比較例１および比較例２のドライヤーカンバスは、それぞれ広幅、高速の抄紙用乾燥部において、従来から使用実績の豊富なカンバスである。
【００７６】
上記実施例１および実施例２と、比較例１および比較例２について、前記図７〜図１０に示す試験方法で測定または計算した、ヨコ剛性（ｄａＮ／３ｃｍ）、ズレ角度（θ１），（θ２）、有効ニュートラルライン厚み（ｍｍ）の測定ならびに計算結果、および接触面積（％）を表３に示す。
【００７７】
【表３】

【００７８】
（ヨコ剛性の確認）
上記の実施例１，実施例２および比較例１，比較例２のドライヤーカンバスの幅方向（緯糸方向）のヨコ剛性を、前記図７に示す３点曲げ剛性の試験装置９０により確認した。なお、試料Ｓには、接紙面方向に荷重を掛けて引っ張り上げて測定した。測定結果を表３に示した。
【００７９】
室温での緯糸方向の３点曲げ剛性の測定結果は、実施例１で０．５２ｄａＮ／３ｃｍ、実施例２で０．７６ｄａＮ／３ｃｍ、比較例１で０．９１ｄａＮ／３ｃｍ、比較例２で０．４９ｄａＮ／３ｃｍであった。一方１２０°加熱下では、実施例１で０．１７ｄａＮ／３ｃｍ、実施例２で０．２５ｄａＮ／３ｃｍ、比較例１で０．３１ｄａＮ／３ｃｍ、比較例２で０．１６ｄａＮ／３ｃｍであった。
【００８０】
従って、緯糸方向の３点曲げ剛性が、実施例２では比較例１と同程度であり、良好であることが確認された。また、実施例１では比較例１に比べると劣るが、現在広幅、高速の単列シリンダー方式の乾燥部に使用実績のある比較例２のドライヤーカンバスよりも優れており、使用可能と判断できる。
【００８１】
（走行安定性の評価）
上記の実施例１，実施例２および比較例１，比較例２のドライヤーカンバスの加熱前および加熱後のズレ角度θ１，θ２を、前記の図８に示すズレ角度測定装置１００により測定して、カンバス走行時の織組織ズレを推定し、カンバスの走行安定性を評価した。測定は、各カンバスについてサンプル数３にて行い、測定結果の平均値を表３に示した。
【００８２】
加熱前のズレ角度（θ１）は、実施例１で１．９°、実施例２で１．８°、比較例１で２．２°、比較例２で２．５°であった。また、加熱後のズレ角度（θ２）は、実施例１で２．１°、実施例２で２．０°、比較例１で３．６°、比較例２で４．１°であった。
【００８３】
したがって、経糸１１に厚さ方向および幅方向の寸法が同じ断面扁平なモノフィラメントを用い、カンバスの厚さが比較例１のカンバスに比べ薄い、実施例１および実施例２のカンバスのズレ角度（θ１），（θ２）は、比較例１および比較例２のカンバスのズレ角度（θ１），（θ２）に比べ小さく、走行安定性が改善されることが判った。
【００８４】
（有効ニュートラルライン厚さの確認）
上記の実施例１，実施例２および比較例１，比較例２のドライヤーカンバスの有効ニュートラルライン厚さを、前記の図９に示す装置１１０により測定し、前述の式（２）で計算し、単列シリンダー方式の乾燥部での湿紙への速度変動の影響度合いを推定した。
【００８５】
接紙面を外側にして測定し、計算した接紙面側表面からのニュートラルラインまでの寸法ｔ１と、反接紙面側を外側にして測定し、計算した接紙面側表面からのニュートラルラインまでの寸法ｔ２の合計の有効ニュートラルライン厚さは、実施例１で１．０７１、実施例２で１．１２６、比較例１で１．３３１、比較例２で１．１４１であった。
【００８６】
したがって、実施例１および実施例２のカンバスとも、比較例１および比較例２のカンバスに比べて、有効ニュートラルライン厚さが小さく、単列シリンダー方式の乾燥部での湿紙の速度変動は少なく、品質等への影響も少ないと判断できる。また、有効ニュートラルライン厚さが小さいので、反接紙面側の緯糸における厚さ方向の寸法をより大きくすることが可能で、比較例１および比較例２のカンバスよりもヨコ剛性の優れたカンバスの製作が可能である。
【００８７】
（表面平滑性の評価）
上記の実施例１および比較例１のドライヤーカンバスにおける接紙面側の接触面積率を、前記のカンバスの接触面の測定方法で測定し、カンバスの接紙面側の接触点の発色パターンを図１２に示した。（実施例２および比較例２は図示せず）
【００８８】
接触面積率は、実施例１で１７．７３％、実施例２で１７．６５％、比較例１で１３．９８％、比較例２で１５．６５％であった。例えば実施例１の接触面積率は比較例１に比べて１２７％と大きく、優れた表面平滑性で有ることが判った。
【００８９】
【発明の効果】
本発明によれば、経糸に断面扁平形状および接紙面側の緯糸に厚さ方向において上下に対向する２つの直線部を有する断面形状のモノフィラメントを用い、また、織物表面に経糸が長浮きする織組織で製作するので、上質紙や塗工用原紙のような高度な品位水準が要求される用途に使用できる表面平滑性に優れた製紙用ドライヤーカンバスが得られる。
【００９０】
さらに、本発明によれば、経糸に断面扁平形状および接紙面側の緯糸に厚さ方向において上下に対向する２つの直線部を有する断面形状のモノフィラメント用い、また、反接紙面側の緯糸に、接紙面側の緯糸より厚さ方向寸法の大きいモノフィラメントを用い、表裏非対称の織組織で製作するので、接紙面側の緯糸層が反接紙面側の緯糸層よりも薄いことにより、カンバスのニュートラルラインが接紙面側に移動した構造となり、有効ニュートラルライン厚さの薄いカンバスとなり、反接紙面側の緯糸の厚さ方向寸法をより一層大きくできるので、幅９００ｃｍ以上、抄速度１，５００ｍ／分以上の広幅・高速の単列シリンダー方式の乾燥部に好適に使用できる、ヨコ剛性に優れた製紙用ドライヤーカンバスが得られる。
【００９１】
加えて、本発明によれば、経糸に断面扁平形状および接紙面側の緯糸に厚さ方向において上下に対向する２つの直線部を有する断面形状のモノフィラメントを用いるので、経糸と緯糸が強固に交錯し、さらに、接紙面側の緯糸に、幅方向両側に各々１つの薄肉部を有する断面形状のモノフィラメントを使用できるので、経糸と緯糸の交錯が一層強固となり走行安定性に優れると共に、経糸と緯糸間の空隙を少なくでき、低い通気度を含む広い通気度範囲の製紙用ドライヤーカンバスが得られる。
【図面の簡単な説明】
【図１】（Ａ）〜（Ｄ）は本発明の製紙機械用ドライヤーカンバスにおける経糸の各種実施形態の断面形状図である。
【図２】（Ａ）〜（Ｃ）は本発明の製紙機械用ドライヤーカンバスにおける接紙面側の緯糸層を構成する緯糸の各種実施形態の断面形状図である。
【図３】（Ａ）〜（Ｆ）は本発明の製紙機械用ドライヤーカンバスにおける反接紙面側の緯糸層を構成する緯糸の各種実施形態の断面形状図である。
【図４】（Ａ）〜（Ｆ）は本発明の製紙機械用ドライヤーカンバスにおける接紙面側の緯糸層を構成する緯糸の異なる実施形態の各種断面形状図である。
【図５】（Ａ）〜（Ｅ）は本発明の製紙機械用ドライヤーカンバスにおける経糸に扁平な断面形状の糸条を用いた各織組織の概略断面図を示すもので、
（Ａ）は接紙面側の緯糸に厚さ方向において上下に対向する２つの直線部を有する断面形状の糸条を用いた緯２重織組織のカンバス織組織、
（Ｂ）は接紙面側の緯糸に厚さ方向において上下に対向する２つの直線部を有する断面形状の糸条を用いた緯２．５重織組織のカンバス織組織、
（Ｃ）は接紙面側に厚さ方向において上下に対向する２つの直線部を有する断面形状の糸条および中間層の緯糸に扁平断面四角形の糸条を用いた緯２．５重織組織のカンバス織組織、
（Ｄ）は接紙面側の緯糸に厚さ方向において上下に対向する２つの直線部を有する断面形状の糸条を用いた緯３重織組織のカンバス織組織、
（Ｅ）は接紙面側に厚さ方向において上下に対向する２つの直線部を有する断面形状の糸条および中間層の緯糸に扁平断面四角形の糸条を用いた緯３重織組織のカンバス織組織である。
【図６】本発明の実施例および比較例の製紙機械用ドライヤーカンバスに用いた接紙面側の経糸が長浮きする織組織の概略説明図を示すもので、
（Ａ）は接紙面側が２／２破れ斜文、反接紙面側が３／１の破れ斜文の緯２重織組織、
（Ｂ）は接紙面側が３／３破れ斜文、反接紙面側が４／２の破れ斜文の緯２重織組織のカンバス織組織である。
【図７】ヨコ剛性測定装置の概略構成図である。
【図８】（Ａ）はズレ角度測定装置におけるズレ角度測定前の概略構成図、
（Ｂ）はズレ角度測定装置におけるズレ角度測定時の概略構成図、
（Ｃ）はズレ角度測定装置により得たズレ寸法からズレ角度を計算する方法の説明図である。
【図９】ニュートラルライン測定装置の概略構成図である。
【図１０】（Ａ）は本発明の実施例１の製紙機械用ドライヤーカンバスにおけるカンバスと湿紙との接触面積の説明図、
（Ｂ）は比較例１の製紙機械用ドライヤーカンバスにおけるカンバスと湿紙との接触面積の説明図である。
【図１１】（Ａ）は従来の製紙機械用ドライヤーカンバスの緯糸方向から見た織組織概略断面図、
（Ｂ）は従来の製紙機械用ドライヤーカンバスの経糸方向から見た織組織概略断面図である。
【図１２】従来の他の製紙機械用ドライヤーカンバスの緯糸方向から見た織組織概略断面図である。
【図１３】（Ａ）は従来のさらに他の製紙機械用ドライヤーカンバスの経糸方向から見た経糸の拡大断面図、
（Ｂ）はその織組織の概略断面図である。
【図１４】製紙機械用ドライヤーカンバスを適用し得る単列の乾燥シリンダーによる乾燥部の概略側面図である。
【図１５】製紙機械用ドライヤーカンバスのニュートラルラインについて説明する、乾燥部における乾燥シリンダーおよびサクションローラに対するドライヤーカンバスと湿紙の接触部の拡大側面図である。
【符号の説明】
１ 乾燥シリンダー
２ ドライヤーカンバス
４ 湿紙
５ サクションロール
１１ 経糸
１１ａ 接紙面側の長浮きする経糸
１２ 接紙面側の緯糸層を構成する緯糸
１３ 反接紙面側の緯糸層を構成する緯糸
１４ 中間層の緯糸
９０ ヨコ剛性測定装置
１００ ズレ角度測定装置
１１０ ニュートラルライン計算用データの測定装置
Ｓ 試料[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a dryer canvas for a paper machine used in a drying section of a paper machine. In particular, the present invention relates to a dryer canvas having surface smoothness that is suitable for applications requiring a high quality level. Furthermore, the present invention relates to a dryer canvas that is preferably used in a drying section in which a single drying cylinder is arranged.
[0002]
[Prior art]
In recent years, a so-called monofilament canvas using a synthetic fiber monofilament having a circular cross section for warp and weft has been widely used for a dryer canvas used in a drying section of a paper machine. This provides excellent dimensional stability due to the rigidity of the monofilament, and can also provide a canvas with excellent antifouling properties due to the smooth yarn surface. Furthermore, it has sufficient strength and absorbs very little moisture. This makes it possible to make a canvas with excellent air permeability.
[0003]
On the other hand, the improvement of the drying section accompanying the increase in the speed of the paper machine, which will be described later, has led to a demand for a canvas having a low thickness and a low air permeability. It may be difficult to achieve due to the three-dimensional voids.
[0004]
In order to realize a canvas having a low air permeability and a small thickness, for example, as shown in FIGS. 11A and 11B, a weft 22 on the paper contacting surface side, a weft 23 on the opposite paper surface side, and a weft 24 on the intermediate layer A flat plastic polymer monofilament twisted yarn is used for the warp 21 to be woven, and the warp density is set to 100%. The long axis of the flat cross section of the warp 21 extends so as to be parallel to the surface of the canvas. There is a proposal to reduce the diagonal length of the canvas mesh opening by the low contour of 21 and to form a horizontal weft direction passage where wefts 22 and 23 are woven with warp yarn 21 (see, for example, Patent Document 1). ).
[0005]
Further, for example, as shown in FIG. 12, at least one of warp 31 and weft (weft 32 on the paper contact surface side and weft 33 on the side opposite to the paper contact surface) is a polymer alloy of polyester and polyethylene, or polyester and polyethylene elastomer. There is a proposal to obtain a canvas having a low air permeability, a small thickness, and improved surface smoothness using a flexible mono-filament made of a polymer alloy (see, for example, Patent Document 2).
[0006]
Further, for example, the present applicant uses a monofilament having an elliptical cross section for the warp 41 as shown in FIGS. 13 (A) and 13 (B), arranges a high warp filling ratio, As a structure in which warp yarns float on the surface of the fabric, we proposed a canvas that secured surface properties, achieved a wide air permeability adjustment range including low air permeability, and improved running stability (Patent Document) 3).
[0007]
On the other hand, conventionally, as a multi-cylinder dryer for papermaking, an upper and lower canvas method in a two-stage upper and lower drying dryer is used (see, for example, FIG. 1 of Patent Document 1). (For example, refer to FIG. 2 of Patent Document 1) Further, in order to cope with high speed papermaking of 1,000 m / min to 1,500 m / min, a drying cylinder is installed horizontally in the running direction as an improvement plan of the single run method. For example, a single-row dryer system such as a Berlan system (trademark of Beloit USA) has been proposed.
[0008]
As shown in FIG. 14, the Berlan method has a wet paper 4 brought into contact with a single row of drying cylinders 1 with a sufficient holding angle, and a suction roll 5 is disposed between the drying cylinders 1, 1. In this way, the wet paper 4 coming on the canvas 2 is sucked onto the canvas 2 to be brought into close contact with the guide 2, and is used for the entire group of the drying section or before the size press. Yes.
[0009]
This method eliminates the so-called free run portion where the wet paper web 4 travels without contacting the canvas 2 between the groups and between the cylinders, so that stabilization at the time of high speed travel of the sheet can be obtained. This makes it possible to control the sheet shrinkage over the entire width during drying, which helps to improve the paper quality. Furthermore, it is possible to eliminate the dryer pocket, which is the cause of moisture unevenness in the machine width direction, and to improve the drying efficiency.
[0010]
When the dryer canvas used in the drying section of the conventional two-stage arrangement of the drying cylinder is used for the single row dryer system having such an arrangement and structure, the following problems occur. Come on.
[0011]
That is, the wet paper is squeezed in the press part and reaches the entrance of the drying section with a moisture content of about 50 to 60%. Therefore, at the initial stage of the drying section, the wet paper still has a lot of water, so that the wet paper is weak in strength and has a property of being easily stretched.
[0012]
In the single-row dryer system shown in FIG. 14, the wet paper web 4 is always carried by a single canvas while in contact with the paper contact surface side of the dryer canvas 2 during one drying group. On the drying cylinder 1, as shown in FIG. 15, the wet paper web 4 is bent along the cylindrical surface of the drying cylinder 1 (1), inside the canvas 2, that is, on the lower side (drying cylinder 1 side). positioned. On the suction roll 5, the wet paper web 4 is located outside the canvas 2 in the state (3) bent along the cylindrical surface of the suction roll 5, that is, on the upper side (the side opposite to the suction roll 5).
[0013]
The paper contact surface of the canvas 2 bent inward of the state (1) is smaller than the length of the canvas in the thickness direction due to the thickness of the canvas 2, in other words, the running speed of the wet paper web 4 is the portion of the canvas body in that portion. Slower than the running speed. Further, the paper contact surface of the canvas 2 bent outward in the state (3) is extended from the length of the canvas 2 in the thickness direction center due to the thickness of the canvas 2. In other words, the running speed of the wet paper web 4 is It becomes faster than the travel speed of the canvas body. For this reason, the wet paper 4 carried on the surface of the canvas 2 on the paper contact surface side is repeatedly stretched and loosened by the expansion and contraction of the paper contact surface of the canvas 2 to adversely affect the wet paper 4, and the shrinkage characteristics of the paper, Defects such as paper breakage occur due to deterioration of the skin and slight vibration of the sheet.
[0014]
In addition, when the canvas 2 travels while being bent inward or outward by a guide roll such as the drying cylinder 1 or the suction roll 5, the canvas 2 is kept at a constant speed regardless of changes in the traveling speed on the paper contact surface side surface or the counter paper contact surface side surface. The traveling position exists in the thickness direction of the canvas. A position where the vehicle travels at a constant speed can be assumed by a line, and this line is called a neutral line. The broken line in FIG. 15 shows this neutral line 6. FIG. 15 shows a case where the neutral line 6 is offset toward the paper contact surface side because the canvas 2 has an asymmetric structure in which the front and back sides are different. In the case of a normal canvas where the front and back structures are completely symmetrical, the neutral line is located at the center in the thickness direction of the canvas.
[0015]
That is, even though the shrinkage rate of the wet paper web 4 is controlled by eliminating the free run that is the merit of the single-row dryer method, when the canvas 2 is thick, the wet paper web 4 is alternately stretched and loosened, Since the merit is lost, it is desirable that the canvas 2 is as thin as possible. However, on the other hand, in a high-speed paper machine with a width of 5 to 9 m, the canvas is required to have more dimensional stability, running stability, etc. From the viewpoint of strength and rigidity, the canvas thickness should be unconditionally reduced. Is not preferred.
[0016]
[Patent Document 1]
Japanese Patent Publication No. 58-28398 (column 7, column 24 to column 8, line 1, FIGS. 1 and 2)
[Patent Document 2]
JP-A-5-59686 (Claim 1)
[Patent Document 3]
JP 2002-155490 A {FIG. 1, FIG. 6 (B)}
[0017]
[Problems to be solved by the invention]
However, as in the canvas described in Patent Document 1, a monofilament having a flat cross section is used for the warp 21 and a yarn having a cross-sectional shape close to the shape of the cross gap of the warp 21 is used for the wefts 22 and 23. Is thin and has a low air permeability, but the rigidity in the width direction suitable for a wider and wider papermaking machine cannot be obtained. Also, since the monofilament whose thickness direction upper surface is not straight is used for the weft 22 on the paper contact surface side, the surface formed by the warp yarn 21 on the paper contact surface side cannot ensure the smoothness required for high-grade paper.
[0018]
In addition, in the case of using a flexible flat monofilament for at least one of the warp 31 and the weft 32 as in the canvas described in Patent Document 2, the surface smoothness is improved, but the thickness is thin, Inferior to the horizontal rigidity, for example, the running stability including the horizontal rigidity suitable for a papermaking machine having a wide width exceeding 9 m at a high speed of 1,500 m / min or more cannot be obtained.
[0019]
Moreover, like the canvas described in Patent Document 3, the warp 41 is made of an elliptical cross-section monofilament, and the warp filling ratio is set as high as 100% to 175%. In order to ensure a wide range of air permeability adjustment including low air permeability, sufficient surface properties that are compatible with high-quality papermaking cannot be obtained, and sufficient weft density is achieved. In order to ensure dimensional stability including displacement resistance, the loom requires a high-power loom, and the canvas woven thereby becomes expensive.
[0020]
Therefore, in the present invention, it can be suitably used in applications that require a high level of quality, such as high-quality paper and coating base paper. It is an object of the present invention to provide a dryer canvas for a papermaking machine that can be used particularly preferably in a high front group and has good surface smoothness and also has rigidity in the weft direction.
[0021]
Furthermore, in a drying section of a single run canvas system or a type in which drying cylinders are arranged in a single row, problems caused by the thickness of the canvas are eliminated, and for example, the canvas width is 9 m or more and the paper making speed is max 1,500 m / min. It is an object of the present invention to provide a dryer canvas for a papermaking machine that can be applied to the above wide and high speed paper machines and has excellent dimensional stability and running stability and a wide air permeability adjustment range.
[0022]
[Means for Solving the Problems]
A dryer canvas for a paper machine according to the present invention is a dryer canvas for a paper machine made of a woven fabric using a warp and a weft of a synthetic fiber, wherein the dryer canvas has at least two layers on the paper contact surface side and the reverse paper contact surface side. The weft layers are monofilaments having a flat cross-sectional shape, and the weft yarns constituting the weft layer on the paper-contacting surface side have a cross-sectional shape having two straight portions facing vertically in the thickness direction. The weft constituting the weft layer on the side opposite to the paper surface is made of a monofilament having a cross-sectional shape having a curved portion at a portion positioned below in the thickness direction, and the thickness direction dimension of the cross section is It is larger than the dimension in the thickness direction of the cross section of the weft constituting the weft layer on the paper contact surface side In addition, the wefts constituting the weft layer on the paper contact surface side and the warp are crimped to each other, and the neutral line of the dryer canvas is present on the paper contact surface side from the central portion in the thickness direction of the dryer canvas. (Claim 1).
[0023]
The dryer canvas for a papermaking machine according to the present invention has a cross-sectional shape of a monofilament weft constituting the weft layer on the paper-contacting surface side, which has two linear portions opposed vertically in the thickness direction, and has a width direction A cross-sectional shape having one thin part on each of both sides (Claim 2).
[0024]
Further, the dryer canvas for a papermaking machine of the present invention comprises the weft layer on the paper contact surface side when the weft constituting the weft layer on the reverse paper surface side is made of a monofilament having a circular cross section and the cross-sectional diameter is Z. The cross-sectional dimensions of the weft yarns are characterized in that the maximum thickness dimension is in the range of 0.35 × Z to 0.5 × Z and the maximum width dimension is in the range of 0.65 × Z to Z (claims). Item 3).
[0025]
The dryer canvas for a papermaking machine according to the present invention is characterized in that the woven structure of the woven fabric is a woven structure having an asymmetric structure between the paper-contacting surface side and the anti-paper-contacting surface side. 4).
[0026]
In the dryer canvas for a papermaking machine according to the present invention, the woven structure of the woven fabric includes two weft layers on the paper contact surface side and the reverse paper contact surface side, and the warp floats long on the paper contact surface side. It is an organization (claim 5).
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of a dryer canvas for a papermaking machine according to the present invention will be described with reference to the drawings.
[0028]
That is, the dryer canvas for papermaking machine of the present invention is a dryer canvas for papermaking machine made of woven fabric using warp and weft of synthetic fibers, and the dryer canvas is at least on the paper contact surface side and the reverse paper contact surface side. A cross-section having two weft layers, wherein the warp is composed of monofilaments having a flat cross-sectional shape, and the wefts constituting the weft layer on the paper-contacting surface side have two linear portions facing vertically in the thickness direction. The wefts constituting the weft layer on the side opposite to the paper surface are composed of monofilaments having a cross-sectional shape having a curved portion in the portion located below in the thickness direction, and the thickness dimension of the cross section Is larger than the dimension in the thickness direction of the cross section of the weft constituting the weft layer on the paper contact surface side.
[0029]
Here, the “monofilament having a flat cross-sectional shape” applied to the warp is a flat quadrangular shape, a flat quadrangular shape with four corners chamfered, an elliptical shape, a long shape, as shown in FIGS. The shape includes a circular shape, a bowl shape, and those obtained by partially deforming the shape, dividing and combining these cross-sectional shapes vertically, and dividing and combining them horizontally.
[0030]
Further, “a monofilament having a cross-sectional shape having two linear portions facing each other in the thickness direction” applied to the weft of the weft layer on the paper-contacting surface side is as shown in FIGS. 2 (A) to 2 (C). In addition, flat rectangles, flat rectangles with chamfered corners, oval shapes, and parts other than these upper and lower straight portions are partially deformed, for example, in the intersecting portion between the thickness direction and the width direction, or in the shape in the thickness direction. A monofilament having a cross-sectional shape.
[0031]
Further, “a monofilament having a cross-sectional shape having a curved portion at a portion positioned downward in the thickness direction” applied to the wefts of the weft layer on the side opposite the paper surface is shown in FIGS. 3 (A) to 3 (F). Such as a circular shape, an elliptical shape, a substantially semicircular shape with chamfered corners, a substantially pentagonal shape, a substantially triangular shape, and the like, and a monofilament having a cross-sectional shape obtained by partially deforming them.
[0032]
By weaving monofilaments having these cross-sectional shapes for warps and wefts, the weft layer on the paper contact surface side has monofilaments that are flat in cross section on the warp yarns, and two linear portions that face the weft yarns in the thickness direction. Since a monofilament having a cross-sectional shape is used, smooth surface properties can be obtained. In particular, since the long floating part in the woven structure in which the warp floats long on the paper contact surface side becomes smoother, the contact area with the wet paper increases, the surface smoothness also improves, and the papermaking requires a high quality level. It can be suitably used for a machine dryer canvas.
[0033]
Furthermore, since a monofilament having a flat cross-sectional shape is used for the warp, and a monofilament having a cross-sectional shape having two linear portions that are vertically opposed to each other in the thickness direction is used for the paper-contacting side weft, the weft of the weft layer on the paper-contacting side is It is easier to crimp than the case of a weft with the same cross-sectional area as a circular shape, and not only the warp but also the weft is crimped, and the cross between the warp and the weft becomes deeper, making it possible to produce a canvas with a thin thickness dimension. . Further, the contact area between the warp and the weft at the crossing portion is large, and the displacement resistance of the canvas is improved.
[0034]
In addition, the weft constituting the weft layer on the side opposite to the paper surface has a cross-sectional shape having a curved portion at a portion positioned below in the thickness direction, and the thickness direction dimension of the cross section is the same as that of the weft on the paper contact surface side. Since a monofilament larger than the thickness direction dimension in the cross section is used, the thickness dimension of the weft is larger than that in the case of using a monofilament with a flat cross section for the weft on the side opposite the paper surface. ) Is improved.
[0035]
The dryer canvas for a papermaking machine according to the present invention has a cross-sectional shape of a monofilament weft constituting the weft layer on the paper-contacting surface side, which has two linear portions opposed vertically in the thickness direction, and has a width direction It is set as the structure which is a cross-sectional shape which has one thin part each on both sides.
[0036]
Here, “a cross-sectional monofilament having a cross-sectional shape having two linear portions opposed to each other in the thickness direction and one thin portion on each side in the width direction” is shown in FIG. ) To monofilament having a cross-sectional shape as shown in FIG.
[0037]
A monofilament with a flat cross section is used for the warp, and a monofilament with a cross-sectional shape having two straight portions facing vertically in the thickness direction is used for the weft on the paper-contacting surface. Compared to the conventional canvas using the knitted fabric, the crossing gap between the warp yarns can be made smaller and the low air permeability can be realized, and the cross-sectional shape of the paper-contacting side wefts is a cross-sectional shape having one thin part on each side in the width direction. Therefore, the thin-walled portion deforms when crossed with the warp, and the weft density can be increased more than when a monofilament without a thin-walled portion is used for the weft, and the thin-walled portion has voids other than the cross-contact portion between the warp and the weft. Therefore, it is easier to realize a low air permeability. Further, since the thin portion is tightened and deformed by the warp, the crossing state of the warp and the weft is further strengthened, and the displacement resistance of the canvas is further improved.
[0038]
Further, the dryer canvas for a papermaking machine of the present invention comprises the weft layer on the paper contact surface side when the weft constituting the weft layer on the reverse paper surface side is made of a monofilament having a circular cross section and the cross-sectional diameter is Z. In the cross-sectional dimension of the weft yarn to be used, the maximum thickness dimension is in the range of 0.35 × Z to 0.5 × Z and the maximum width dimension is in the range of 0.65 × Z to Z.
[0039]
As a result of intensive studies and studies, the inventors have come to the conclusion that the above configuration is preferable as one configuration of a dryer canvas for papermaking machines that can solve the above problems. In particular, a dryer canvas used in the front stage of a single part for making high-quality paper, having an air permeability of 1500 to 4000 cm. ^Three / Cm ² In order to obtain a product having a relatively low air permeability of about min, in addition to the above configuration, when the number of weft layers is Y, the weave density of the wefts is (15.5 to 18.5) × Y ( It is derived that it is preferable to set the range after heat setting.
[0040]
The results of the characteristics obtained during the trial production are as follows. That is,
If the maximum thickness dimension of the weft on the paper-contacting surface side is further smaller than the above range, the canvas body will have insufficient lateral rigidity. If the weaving density of the weft is increased, the weaving and driving of the weft will cause the fabric to vibrate greatly due to the bumping, thereby deteriorating the surface properties of the canvas. Also, the neutral line moves away from the paper contact surface.
[0041]
When the maximum thickness dimension of the weft on the paper-contacting surface side is further larger than the above range, the thickness of the canvas main body is increased, the gap in the canvas main body is increased, and it is difficult to obtain a low air permeability.
[0042]
When the maximum width dimension of the weft on the paper-contacting surface side is further smaller than the above range, the rigidity in the horizontal direction of the canvas body is lowered. If the weaving density of the weft is increased, it will be difficult when weaving the weaving of the weaving and the surface properties of the canvas will deteriorate. Further, the contact area with the warp is reduced, and the resistance to misalignment is also lowered. Furthermore, the neutral line moves away from the paper contact side.
[0043]
If the maximum width dimension of the weft on the paper-contacting surface side is further larger than the above range, weft twist is likely to occur, and warp crimp becomes large, leading to deterioration of the surface property of the canvas, and the resistance to misalignment also decreases.
[0044]
In the dryer canvas for a papermaking machine according to the present invention, the woven structure of the woven fabric is a woven structure having an asymmetric structure between the paper-contacting surface side and the paper-contacting surface side.
[0045]
The weaving structure used in the dryer canvas for papermaking machine of the present invention is as shown in FIGS. 5 (A) to 5 (E). As shown in FIG. 6B, a woven structure in which the paper contact surface and the reverse paper contact surface are asymmetric is included.
[0046]
The woven structure in FIG. 5 has a structure in which the warp 11 is symmetrical with the front and back sides, and the cross-sectional shape of the warp 11 and the weft 12 on the paper contact surface side or the weft 14 of the intermediate layer is configured as described above. Is a woven structure that has been widely used as a papermaking canvas. In these woven structures, the weft 12 on the paper contact surface side and the weft 13 on the opposite paper surface side are overlapped in the thickness direction. The weave structure is a weft double weave as shown in FIG. 5 (A), and a weft of 2.5 weaves in which wefts 14 of the intermediate layer are woven at predetermined intervals as shown in FIGS. 5 (B) and 5 (C). 5D and FIG. 5E, a weft triple weave in which the wefts 14 of the intermediate layer are densely woven is used, so that the wefts, that is, the wefts 12 on the paper contact side, Various types of canvases are manufactured by changing the wefts 13 on the paper side and the wefts 14 of the intermediate layer in various combinations.
[0047]
5A to 5E, the warp 11 has a cross-sectional shape shown in FIGS. 1A to 1D. Further, the weft 12 on the paper contact surface side indicated by a square cross-sectional shape has a cross-sectional shape as shown in FIGS. 2 (A) to 2 (C) or FIGS. 4 (A) to 4 (F). 5 (A) to 5 (E), the weft 13 on the side opposite to the paper surface indicated by a circular cross-sectional shape has a cross-sectional shape as shown in FIGS. 3 (A) to 3 (F). The weft 14 of the intermediate layer may be selected from a cross-sectional shape group of wefts on the paper contact side or a cross-sectional shape group of wefts on the side of the paper-contact side, that is, one of the shapes shown in FIGS.
[0048]
6A and 6B has an asymmetric structure in which the warp 11 has a larger number of wefts 12 woven from the paper-contacting surface side than the number of wefts 13 woven from the paper-contacting surface side. This woven structure is suitably used for a canvas that requires a smoother surface property because the warp yarn 11a is long floating on the paper contact surface side. In addition, since the weft 12 on the paper contact surface side and the weft 13 on the side opposite the paper contact surface are shifted from each other in the thickness direction, there is an advantage that the canvas is thin and the air permeability is easily reduced. Care must be taken when designing the overall structure of the fabric because there is a tendency that it is difficult to ensure the deviation characteristics, which is an index of shape stability, the risk of wrinkles, and the horizontal rigidity, which is an index of running stability.
[0049]
As described above, in the single-row dryer system, the wet paper web 4 and the canvas 2 are located at a constant speed with respect to the roll, and the wet paper web 4 and the canvas 2 travel at different speeds than the canvas 2 travel speed. It gets faster and slower. Strictly speaking, this phenomenon is caused by the arc shape of the traveling (rotating) drying cylinder 1 and the suction roll 5, the thickness of the canvas 2, and the neutral line 6 assumed in the thickness of the canvas 2 described in FIG. Depending on the position, the speed of the paper contact surface side surface (wet paper speed) changes with respect to the neutral line 6.
[0050]
When the canvas 2 is bent while the papermaking machine is in operation, the surface speed of the paper contact surface and the reverse paper contact surface changes depending on the thickness of the canvas 2, but even if the canvas 2 is bent at the position of the neutral line 6. The speed does not change and is constant. In a state in which the canvas 2 is bent, the speed of the paper contact surface side surface changes depending on the dimension (distance) in the thickness direction between the neutral line 6 and the paper contact surface surface, and the neutral line 6 and the paper contact surface surface If the dimension in the thickness direction is small, the change in speed is small, and if the dimension in the thickness direction is large, the change in speed becomes large.
[0051]
When the thickness dimension (distance) between the neutral line 6 and the paper contact surface is small, the neutral line 6 is a normal canvas having a front and back equivalent structure in the center of the canvas 2 in the thickness direction, and the thickness is The same speed change reduction effect as in the case of a thin film is obtained.
[0052]
As shown in FIGS. 3 (A) to 3 (F), the weft 13 constituting the weft layer on the side opposite to the paper surface has a curved portion at the lower portion in the thickness direction. By using a monofilament having a thickness dimension larger than that of the weft constituting the weft layer, the neutral line 6 is moved to a position closer to the paper contact surface, and the warp 11 is shown in FIGS. 1 (A) to 1 (D). As shown in the figure, the monofilament having a flat cross section is used, and the dimension in the thickness direction by the weaving using the monofilament having two linear portions vertically opposed to the weft 12 on the paper contact surface side in the thickness direction is considered to be small. Thus, since the speed change of the wet paper 4 during paper making becomes smaller, a dryer canvas for a papermaking machine suitable for use in a single row dryer type drying section is obtained.
[0053]
Further, by weaving the woven structure with the asymmetrical woven structure as shown in FIGS. 6 (A) and 6 (B), the neutral line 6 is moved further to the paper contact surface side, and the wet paper 4 The travel speed change is further reduced, and there is a margin for increasing the thickness of the canvas 2 by the amount of movement of the neutral line 6 toward the paper contact surface side, and the cross-sectional thickness direction dimension of the weft 13 on the reverse contact paper surface side is increased. This makes it possible to manufacture a canvas with a large horizontal rigidity.
[0054]
In the dryer canvas for a papermaking machine according to the present invention, the woven structure of the woven fabric includes two weft layers on the paper contact surface side and the reverse paper contact surface side, and the warp yarn 11a floats on the paper contact surface side. The structure is a woven structure.
[0055]
A monofilament with a flat cross section shown in FIGS. 1A to 1D is used for the warp 11 constituting the paper contact surface side, and the weft 12 on the paper contact surface side is used in the thickness direction shown in FIGS. 2A to 2C. 6A and 6B, and further woven with a woven structure in which the warp yarn 11a floats long on the paper-contacting surface side, using monofilaments having a cross-sectional shape having two linear portions opposed vertically. Therefore, in addition to the flatness of the surface of the warp 11a and the weft 12, the warp 11a having a flat cross section is easily crimped at the intersection with the weft 12, and the weft 12 is also a cross section with the warp 11a. It is easier to crimp than in the case of the above, and the smoothness of the long floated warp 11a is further increased, and the contact area with the wet paper 4 is improved.
[0056]
Therefore, according to the present invention, it can be suitably used in applications that require a high level of quality, such as paper making of high-quality paper and coating base paper. A dryer canvas having good surface smoothness, flexibility in the warp direction, and excellent lateral rigidity in the weft direction, which can be particularly suitably used for the front group having a relatively high rate, can be realized.
[0057]
In addition, the thickness can be applied to the drying section of single-run canvas and single-row dryer systems, and can be adjusted to a suitable dimension (distance) from the paper-contacting surface to the neutral line, and the weft thickness on the side facing the paper-contacting surface. Since the directional dimensions can be increased, for example, excellent dimensional stability, running stability, and wide air permeability adjustment that can be applied to a wide and high speed paper machine with a canvas width of 9 m or more and a paper making speed of max 1,500 m / min or more. A dryer canvas for a papermaking machine having a capacity range can be realized.
[0058]
In addition, although the Example and comparative example of this invention are demonstrated later, it is as follows about the measuring apparatus and measuring method of the various characteristics in connection with the evaluation.
1. "Air permeability"
It conforms to the fragile method in JIS L-1096: 1999 “General Textile Test Method”. The amount of air that has passed through the sample under a pressure of 125 Pa is converted and displayed per unit area per minute, in units (cm ^Three / Cm ² ・ Indicated by min).
[0059]
2. "3-point bending stiffness"
With the three-point bending test apparatus 90 shown in FIG. 7, both ends of the sample S having a width of 30 mm (dimension in the front and back direction in FIG. 7) are locked to a round bar 91 having a diameter of 20 mm fixedly spaced apart by 100 mm. When the center portion of the sample S is pulled up by the roller 92 having a diameter of 10 mm, the display value of the load meter (not shown) increases with the amount of pulling up, but the load meter display value does not increase when the sample S is pulled up to some extent. The maximum load at this time is referred to as a three-point bending stiffness value and is expressed in units (daN / 3 cm). The test was measured at room temperature and under 120 ° heating. The larger the numerical value, the higher the 3-point bending rigidity.
[0060]
3. "Deviation angle"
8A and 8B show a misalignment angle measuring device 100, in which one end of the lateral arms 102 and 103 is attached to the upper end portion and the base end portion of the fixed column 101 so as to be swingable up and down, and the other end is a connecting arm The upper horizontal arm 102 is normally fixed to the fixed horizontal arm 105 with a pin 106. An upper end of the sample S having a predetermined length and a predetermined width is fixed to the upper lateral arm 102, and a load W of 1 kg per 1 cm width of the sample S is suspended from the lower end. In this state, the lower end of the sample S is fixed to the lower horizontal arm 103, and then the load W is removed. In this way, the sample S is fixed as shown in FIG. 8A, the pin 106 is pulled out, and a downward moment is applied as shown in FIG. 8B. After leaving in this state for a certain period of time, a displacement dimension x in which the pointer 107 is rotated clockwise about the pivot pin 108 is measured by the scale 109, and heat treatment is performed at a temperature of 180 ° C. for a certain period of time. Thereafter, the displacement dimension x (after heating) is measured again.
[0061]
As shown in FIG. 8C, the displacement angles θ1 (before heating) and θ2 (after heating) are calculated by calculating the displacement dimension x (mm) and the length from the pivot pin 108 to the tip of the pointer 107 as L ( = 120 mm), it is calculated by the following equation (1).

From the displacement angles θ1 and θ2 obtained from the above, the displacement of the weave structure during canvas traveling is estimated and used for evaluating the traveling stability of the canvas.
[0062]
4). "Effective neutral line thickness"
FIG. 9 shows an apparatus 110 for measuring the calculation data of the neutral position Np, which is 6.1 kg (1.74 kg) in the warp direction with respect to the sample S adjusted to a weft direction width dimension of 35 mm (dimension in the front and back direction of the paper surface). / 150), a test length of about 150 mm is applied in the warp direction, and the test piece is wound around a roll 111 having a diameter of 100.9 mm so that the test length comes in contact with the roll surface. 6.1 kg (1.74 kg / cm) In a state where the load W is applied, a paper tape is attached to the outer surface of the sample S, and the sample length mark position of the sample is marked on the paper tape. Remove the paper tape and measure the marking length with a straight ruler.
[0063]
The test length reading L (mm) on the straight line obtained from the above, the test length reading Lr (mm) when wound around the roll 111, the diameter dimension D (= 100.9 mm) of the roll 111, the canvas thickness t ( mm), the neutral position Np (position ratio from the outside of the canvas to the neutral line when the thickness of the canvas is 1) is calculated by the following expression (2).
[0064]
[Formula 1]

[0065]
Np (corresponding to (3) in FIG. 15) measured and calculated by winding the paper-contacting side outward is PS _Np Measure Np (corresponding to (1) in FIG. 15) measured and calculated by turning the reverse paper surface side outward. _Np The thickness dimension t1 from the paper contact surface to the neutral line when the paper contact surface side is on the outside, and the thickness dimension t2 from the paper contact surface when the counter paper contact surface side is on the outside are expressed by the following equation (3) ( Calculate in 4).
t1 = PS _Np Xt (3)
t2 = (1-BS _Np ) × t (4)
[0066]
The sum of the thickness dimensions t1 and t2 is regarded as the effective neutral line thickness, and the degree of change in speed exerted on the wet paper 4 by the canvas 2 applied to the single run method or the single row dryer method is evaluated as the thickness. It is evaluated that the smaller the value, the less the influence of the speed change on the wet paper 4.
[0067]
5. "Contact area of canvas contact surface"
A sample was cut from the canvas, and pressure sensitive paper (manufactured by Fuji Photo Film Co., Ltd.) was placed on the sample, and a contactor having a diameter of 52 mm was pressed with a load of 400 daN for 30 seconds to develop a color at the contact point. This was copied, a color pattern copy of this contact point was taken into a personal computer with a scanner, and the contact area ratio (%) was determined by image analysis. The larger the contact area ratio, the smoother the paper contact surface of the canvas.
[0068]
(Example)
Next, the Example of this invention and the comparative example with respect to this Example are demonstrated based on Table 1-3. In Tables 1 to 3, TM represents a polyester monofilament, PS represents a paper contact surface side, and BS represents a paper contact surface side.
[0069]
[Table 1]

[0070]
(Example 1)
The dryer canvas of Example 1 was manufactured based on the specifications shown in Table 1 and the woven structure shown in FIG. That is, the warp yarn 11 has a dimension of 0.30 mm thick × 0.56 mm wide square polyester monofilament {cross-sectional shape in FIG. 1A}, and the weft 12 on the paper contact side has a thickness of 0.30 mm × width 0 .65 mm cross-sectional square polyester monofilament {cross-sectional shape of FIG. 2 (A)}, cross-sectional polyester monofilament having a diameter of 0.70 mm {cross-sectional shape of FIG. The weft double weave structure with 2/2 broken torsion on the paper contact side and 3/1 on the reverse paper side, and the warp 11a on the paper contact side floated long. The warp density was 54.4 pieces / 2.54 cm. The weft density was 17.7 pieces × 2 layers / 2.54 cm. The manufactured dryer canvas has a thickness of 1.49 mm and an air permeability of 2,400 cm. ^Three / Cm ² ・ It was min.
[0071]
(Example 2)
The dryer canvas of Example 2 was manufactured based on the specifications shown in Table 1 and the weave structure shown in FIG. That is, the warp yarn 11 has a dimension of 0.30 mm thick × 0.56 mm wide square polyester monofilament {cross-sectional shape in FIG. 1A}, and the weft 12 on the paper contact side has a thickness of 0.30 mm × width 0 .65 mm cross-sectional square polyester monofilament {cross-sectional shape of FIG. 2 (A)}, cross-sectional circular polyester monofilament {diameter of FIG. 3 (A)} having a diameter of 0.80 mm is used for the weft 13 on the side opposite to the paper surface. The weft double weave structure with 2/2 broken torsion on the paper contact side and 3/1 on the reverse paper side, and the warp 11a on the paper contact side floated long. The warp density was 54.2 / 2.54 cm. The latitude density was 17.5 × 2 layers / 2.54 cm. The manufactured dryer canvas has a thickness of 1.60 mm and an air permeability of 2,500 cm. ^Three / Cm ² ・ It was min.
[0072]
[Table 2]

[0073]
(Comparative Example 1)
The dryer canvas of Comparative Example 1 was manufactured based on the specifications shown in Table 2 and the woven structure shown in FIG. That is, the warp yarn has dimensions of 0.30 mm thick × 0.56 mm wide square polyester monofilament {cross-sectional shape in FIG. 1A}, the weft yarn 12 on the paper contact surface side, and the weft yarn 13 on the reverse paper surface side have a diameter. A circular polyester monofilament having a cross section of 0.70 mm was used, and the warp on the paper contact side was long floated with a weft double weave structure in which the paper contact side was 2/2 torn and the reverse paper side was 3/1. The warp density was 53.0 pieces / 2.54 cm, and the weft density was 17.9 pieces × 2 layers / 2.54 cm. The manufactured dryer canvas has a thickness of 1.74 mm and an air permeability of 3,000 cm. ^Three / Cm ² ・ It was min.
[0074]
(Comparative Example 2)
The dryer canvas of Comparative Example 2 was produced based on the specifications shown in Table 2 and the woven structure shown in FIG. That is, the warp yarn is 0.25 mm thick by 0.65 mm wide square polyester monofilament {cross-sectional shape in FIG. 1A}, the weft 12 on the paper contact surface side, and the weft 13 on the reverse paper surface side are diameters. A 0.60 mm circular polyester monofilament with a cross section, the weft double weave structure in which the paper contact surface side is 2/2 torn and the reverse paper surface side is 3/1, and the warp on the paper contact surface side is long floated. The warp density was 46.7 pieces / 2.54 cm, and the weft density was 20.1 pieces × 2 layers / 2.54 cm. The manufactured dryer canvas has a thickness of 1.34 mm and an air permeability of 1,900 cm. ^Three / Cm ² ・ It was min.
[0075]
The dryer canvases of Comparative Example 1 and Comparative Example 2 described above are canvases that have been widely used in the past in wide and high speed paper drying sections.
[0076]
About the said Example 1 and Example 2, and the comparative example 1 and the comparative example 2, it measured or calculated with the test method shown in the said FIGS. 7-10, the horizontal rigidity (daN / 3cm), the deviation angle ((theta) 1), ( Table 3 shows the measured and calculated results of θ2), the effective neutral line thickness (mm), and the contact area (%).
[0077]
[Table 3]

[0078]
(Confirmation of horizontal rigidity)
The transverse stiffness in the width direction (weft direction) of the dryer canvases of Examples 1 and 2 and Comparative Examples 1 and 2 was confirmed by the three-point bending stiffness test apparatus 90 shown in FIG. The sample S was measured by applying a load in the direction of the paper contact surface and pulling it up. The measurement results are shown in Table 3.
[0079]
The measurement results of the three-point bending stiffness in the weft direction at room temperature were 0.52 daN / 3 cm in Example 1, 0.76 daN / 3 cm in Example 2, 0.91 daN / 3 cm in Comparative Example 1, and 0 in Comparative Example 2. It was .49 daN / 3 cm. On the other hand, under 120 ° heating, Example 1 was 0.17 daN / 3 cm, Example 2 was 0.25 daN / 3 cm, Comparative Example 1 was 0.31 daN / 3 cm, and Comparative Example 2 was 0.16 daN / 3 cm.
[0080]
Therefore, it was confirmed that the three-point bending rigidity in the weft direction is the same as that in Comparative Example 1 in Example 2, and is good. Further, in Example 1, it is inferior to Comparative Example 1, but it is superior to the dryer canvas of Comparative Example 2 which has been used in a wide-width, high-speed single-row cylinder type drying section and can be judged to be usable.
[0081]
(Evaluation of running stability)
The deviation angles θ1 and θ2 before and after the heating of the dryer canvas of Example 1, Example 2 and Comparative Example 1 and Comparative Example 2 are measured by the deviation angle measuring device 100 shown in FIG. We estimated the fabric texture deviation during the running of the canvas and evaluated the running stability of the canvas. The measurement was performed with 3 samples for each canvas, and the average value of the measurement results is shown in Table 3.
[0082]
The deviation angle (θ1) before heating was 1.9 ° in Example 1, 1.8 ° in Example 2, 2.2 ° in Comparative Example 1, and 2.5 ° in Comparative Example 2. Further, the deviation angle (θ2) after heating was 2.1 ° in Example 1, 2.0 ° in Example 2, 3.6 ° in Comparative Example 1, and 4.1 ° in Comparative Example 2. .
[0083]
Therefore, a monofilament having a flat cross section having the same thickness and width dimensions is used for the warp 11, and the canvas is thinner than the canvas of Comparative Example 1, and the canvas misalignment angle (θ 1 ) And (θ2) are smaller than the canvas shift angles (θ1) and (θ2) of Comparative Example 1 and Comparative Example 2, and it was found that the running stability was improved.
[0084]
(Confirmation of effective neutral line thickness)
The effective neutral line thickness of the dryer canvas of Example 1, Example 2 and Comparative Example 1, Comparative Example 2 is measured by the apparatus 110 shown in FIG. 9 and calculated by the above-described equation (2). The effect of speed fluctuation on the wet paper in the single row cylinder type drying section was estimated.
[0085]
Measured with the paper-contacting surface on the outside, the calculated dimension t1 from the paper-contacting surface side to the neutral line, and measured with the anti-paper-contacting surface side on the outside, the calculated dimension t2 from the paper-contacting surface side to the neutral line The total effective neutral line thickness was 1.071 in Example 1, 1.126 in Example 2, 1.331 in Comparative Example 1, and 1.141 in Comparative Example 2.
[0086]
Therefore, both the canvases of Example 1 and Example 2 have a smaller effective neutral line thickness than the canvases of Comparative Example 1 and Comparative Example 2, and less fluctuation in the speed of the wet paper in the single-row cylinder type drying section. Therefore, it can be judged that there is little influence on quality and the like. In addition, since the effective neutral line thickness is small, it is possible to increase the dimension in the thickness direction of the weft on the side of the paper-contacting surface, and the canvas having superior lateral rigidity than the canvases of Comparative Example 1 and Comparative Example 2 Production is possible.
[0087]
(Evaluation of surface smoothness)
The contact area ratio on the paper contact surface side in the dryer canvas of Example 1 and Comparative Example 1 is measured by the above-described method for measuring the contact surface of the canvas, and the color development pattern of the contact points on the paper contact surface side of the canvas is shown in FIG. Indicated. (Example 2 and Comparative Example 2 are not shown)
[0088]
The contact area ratio was 17.73% in Example 1, 17.65% in Example 2, 13.98% in Comparative Example 1, and 15.65% in Comparative Example 2. For example, the contact area ratio of Example 1 was as large as 127% compared to Comparative Example 1, indicating that the surface smoothness was excellent.
[0089]
【The invention's effect】
According to the present invention, a monofilament having a flat cross-sectional shape as a warp and a cross-sectional monofilament having two linear portions opposed to each other in the thickness direction on a weft on the paper contact surface side, and a woven fabric in which a warp floats long on the surface of the fabric. Since it is produced by a tissue, a papermaking dryer canvas excellent in surface smoothness that can be used for applications requiring high quality levels such as high-quality paper and coating base paper can be obtained.
[0090]
Further, according to the present invention, the cross-sectional monofilament having a flat cross-sectional shape and a weft on the paper-contacting surface side in the thickness direction is used for the warp, and the weft on the paper-contacting surface side is used. A monofilament with a larger dimension in the thickness direction than the weft on the paper-contacting side is used, and the weft layer on the paper-contacting side is thinner than the weft layer on the anti-contacting-surface side. Is moved to the paper contact surface side, resulting in a canvas with a thin effective neutral line thickness, and the weft thickness dimension on the side opposite to the paper contact surface side can be further increased, resulting in a width of 900 cm or more and a paper making speed of 1,500 m / min or more. A paper-making dryer canvas excellent in horizontal rigidity that can be suitably used in a wide and high-speed single-row cylinder type drying section.
[0091]
In addition, according to the present invention, the warp and the weft are firmly crossed because the warp and the weft on the paper-contacting side use a monofilament having a cross-sectional shape having two linear portions opposed vertically in the thickness direction. Furthermore, since the cross-sectional monofilament having one thin portion on each side in the width direction can be used for the weft on the paper contact surface side, the crossing of the warp and the weft becomes stronger and the running stability is excellent, and the warp and the weft The space between them can be reduced, and a paper dryer canvas having a wide air permeability range including a low air permeability can be obtained.
[Brief description of the drawings]
FIGS. 1A to 1D are cross-sectional views of various embodiments of warps in a dryer canvas for a papermaking machine according to the present invention.
FIGS. 2A to 2C are cross-sectional views of various embodiments of wefts constituting a weft layer on the paper contact surface side in a dryer canvas for a papermaking machine of the present invention.
FIGS. 3A to 3F are cross-sectional views of various embodiments of wefts constituting the weft layer on the side opposite to the paper surface in the dryer canvas for papermaking machines of the present invention.
4A to 4F are various cross-sectional shapes of different embodiments of wefts constituting a weft layer on the paper contact surface side in a dryer canvas for a papermaking machine of the present invention.
FIGS. 5A to 5E are schematic cross-sectional views of each woven structure using a thread having a flat cross-sectional shape for warp in a dryer canvas for papermaking machine according to the present invention;
(A) is a canvas weave structure having a weft double weave structure using yarns having a cross-sectional shape having two straight portions vertically opposed to the weft on the paper-contacting surface side in the thickness direction;
(B) is a canvas weave structure having a weft 2.5 layer weave structure using yarns having a cross-sectional shape having two straight portions vertically opposed in the thickness direction to the weft thread on the paper contact surface side,
(C) is a weft 2.5 double weave structure using a cross-sectionally shaped yarn having two straight portions facing vertically in the thickness direction on the paper contact surface side and a weft of a flat cross section in the weft of the intermediate layer. Canvas weaving organization,
(D) is a canvas weave structure having a weft triple weave structure using yarns having a cross-sectional shape having two linear portions opposed to the weft on the paper-contacting surface side in the thickness direction,
(E) is a canvas weave having a weft triple weave structure using a cross-sectionally shaped yarn having two linear portions facing vertically in the thickness direction on the paper contact surface side, and a yarn having a flat cross-sectional square shape as a weft of an intermediate layer. It is an organization.
FIG. 6 is a schematic explanatory view of a woven structure in which warp yarns on the paper contact surface side used in the dryer canvas for papermaking machines of Examples and Comparative Examples of the present invention are floated;
(A) is a weft double weave structure in which the paper-contacting surface side is 2/2 torn and the anti-paper-contacting surface side is 3/1,
(B) is a canvas weave structure having a weft double weave structure in which the paper contact surface side is 3/3 torn and the reverse paper face side is 4/2.
FIG. 7 is a schematic configuration diagram of a horizontal stiffness measuring device.
FIG. 8A is a schematic configuration diagram before measuring a deviation angle in the deviation angle measuring apparatus;
(B) is a schematic configuration diagram at the time of measuring a deviation angle in a deviation angle measuring device;
(C) is explanatory drawing of the method of calculating a deviation angle from the deviation dimension obtained by the deviation angle measuring apparatus.
FIG. 9 is a schematic configuration diagram of a neutral line measuring apparatus.
FIG. 10A is an explanatory diagram of a contact area between a canvas and a wet paper in a dryer canvas for a papermaking machine according to Embodiment 1 of the present invention;
(B) is explanatory drawing of the contact area of the canvas and wet paper in the dryer canvas for papermaking machines of the comparative example 1. FIG.
FIG. 11A is a schematic cross-sectional view of a woven structure as viewed from the weft direction of a dryer canvas for a conventional paper machine,
(B) is a schematic cross-sectional view of a woven structure as viewed from the warp direction of a conventional dryer canvas for papermaking machines.
FIG. 12 is a schematic cross-sectional view of a woven structure of another conventional paper machine dryer canvas viewed from the weft direction.
FIG. 13A is an enlarged cross-sectional view of a warp as seen from the warp direction of still another dryer canvas for papermaking machine,
(B) is a schematic sectional view of the woven structure.
FIG. 14 is a schematic side view of a drying section using a single row drying cylinder to which a dryer canvas for a papermaking machine can be applied.
FIG. 15 is an enlarged side view of a contact portion between a dryer canvas and a wet paper web with respect to a drying cylinder and a suction roller in a drying section, explaining a neutral line of the dryer canvas for a papermaking machine.
[Explanation of symbols]
1 Drying cylinder
2 Dryer canvas
4 wet paper
5 Suction roll
11 Warp
11a Long floating warp on the paper contact side
12 Wefts constituting the weft layer on the paper-contacting side
13 Weft constituting the weft layer on the side opposite the paper surface
14 Weft of middle layer
90 Horizontal stiffness measuring device
100 deviation angle measuring device
110 Neutral line calculation data measurement device
S sample

Claims (5)

A dryer canvas for a papermaking machine comprising a woven fabric using warps and wefts of synthetic fibers, wherein the dryer canvas is:
At least two weft layers on the paper contact side and the reverse paper side are provided,
The warp consists of a monofilament having a flat cross-sectional shape,
The weft constituting the weft layer on the paper-contacting surface side is composed of a monofilament having a cross-sectional shape having two straight portions opposed vertically in the thickness direction,
The weft constituting the weft layer on the side opposite to the paper surface is made of a monofilament having a cross-sectional shape having a curved portion at a portion positioned below in the thickness direction, and the thickness direction dimension of the cross section is the paper-contacting surface side. the much larger than the thickness dimension of the cross section of the weft constituting the weft layer, and the weft constituting the weft layer of the contact paper side and with the warp crimp with each other, the neutral line of the drier canvas, the dryer A dryer canvas for a papermaking machine, wherein the dryer canvas is present on the paper contact surface side from the central portion in the thickness direction of the canvas. The cross-sectional shape of the monofilament weft constituting the weft layer on the paper-contacting surface side is a cross-sectional shape having two straight portions that are vertically opposed in the thickness direction and one thin portion on each side in the width direction. The dryer canvas for a papermaking machine according to claim 1, wherein the dryer canvas is provided.   When the weft constituting the weft layer on the side opposite to the paper surface is made of a monofilament having a circular cross section, when the cross-sectional diameter is Z, the maximum thickness dimension is the cross-sectional dimension of the weft layer constituting the weft layer on the paper surface side. The dryer canvas for a papermaking machine according to claim 1, wherein the maximum width dimension is in the range of 0.35xZ to 0.5xZ and 0.65xZ to Z.   The dryer canvas for a papermaking machine according to any one of claims 1 to 3, wherein the woven structure of the woven fabric is a woven structure having an asymmetric structure between the paper-contacting surface side and the paper-contacting surface side.   The woven structure of the woven fabric is a woven structure having two weft layers on the paper-contacting surface side and the anti-paper-contacting surface side, and a warp floats long on the paper-contacting surface side. 4. A dryer canvas for a papermaking machine according to any one of 4 above.

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