Fiber bundle with pieced part, process for producing same, and process for producing carbon fiber

Abstract

A fiber bundle which has a pieced part formed by jetting a pressurized fluid against a fiber-bundle overlap is formed either by directly superposing the ending part of a fiber bundle composed of many fibers on the beginning part of another fiber bundle composed of many fibers or by superposing the end part and the beginning part on a jointing fiber bundle composed of many fibers, whereby the many fibers of the fiber bundles are interlaced with one another to thereby piece up the fiber bundles. The pieced part comprises an opened-fiber part in which the fibers have been opened and interlaced-fiber parts respectively located on both sides thereof, each interlaced-fiber part being composed of a plurality of constituent interlaced parts located apart in the width direction for the fiber bundle.

1 . A fiber bundle having a fiber joint portion comprising either a superposed fiber bundle portion in which one end portion of a first fiber bundle of multiple fibers and one end portion of a second fiber bundle of multiple fibers are superposed or two superposed fiber bundle portions formed in a joint fiber bundle where one end portion of a first fiber bundle of multiple fibers and one end portion of a second fiber bundle of multiple fibers are respectively superposed on said joint fiber bundle wherein each of said superposed fiber bundle portions comprises two or more interlaced fiber portions in which said fibers are interlaced and that are located apart from each other in the length direction of the fiber bundles, and an unraveled fiber portion in which said fibers are unraveled and that is located between said two or more interlaced fiber portions, and in addition, each of said interlaced fiber portions comprises two or more interlaced sub-portions composed of said multiple fibers of one fiber bundle interlaced with said multiple fibers of the other fiber bundle in said superposed fiber bundle portion and located at intervals in the width direction of said fiber bundles, so that said two or more interlaced fiber portions act to join said fiber bundles in said superposed fiber bundle portion. 
     
     
         2 . The fiber bundle according to  claim 1 , wherein both said first fiber bundle and said second fiber bundle are precursor fiber bundles designed for carbon fiber production. 
     
     
         3 . The fiber bundle according to  claim 2 , wherein said joint fiber bundle has a heat conductivity of 3 to 700 W/m·K. 
     
     
         4 . The fiber bundle according to  claim 3 , wherein said joint fiber bundle is a carbon fiber bundle having a drape value of 2 to 15 cm and a flatness of 20 or more. 
     
     
         5 . The fiber bundle according to  claim 4 , wherein the fineness of said joint fiber bundle is 0.2 to 3.0 times that of said first fiber bundle and that of said second fiber bundle. 
     
     
         6 . The fiber bundle according to  claim 4 , wherein said fiber joint portion has a tensile strength of 20 g/tex or more at room temperature. 
     
     
         7 . The fiber bundle according to  claim 1 , wherein each of said interlaced fiber portions has a length of 8 to 30 mm in the length direction of said fiber bundle, and said unraveled fiber portion has a length of 30 to 100 mm in the length direction of said fiber bundle. 
     
     
         8 . A production method for a fiber bundle having a fiber joint portion comprising applying a pressurized fluid emitted from a fiber interlacing apparatus to each of superposed fiber bundle portions in a fiber bundle that has either a superposed fiber bundle portion in which one end portion of a first fiber bundle of multiple fibers and one end portion of a second fiber bundle of multiple fibers are superposed or two superposed fiber bundle portions formed in a joint fiber bundle where one end portion of a first fiber bundle of multiple fibers and one end portion of a second fiber bundle of multiple fibers are respectively superposed on said joint fiber bundle, so that said fibers are interlaced with each other to join said fiber bundles in said superposed fiber bundle portions; wherein said fiber interlacing apparatus comprises a first fluid jetting hole series comprising a plurality of fluid jetting holes aligned at intervals along a first line in the width direction of said fiber bundles and a second fluid jetting hole series comprising a plurality of fluid jetting holes aligned at intervals along a second line that is parallel to the first line and that is positioned with an interval in the length direction of said fiber bundles to the first line, and works to emit pressurized fluid jets from said plurality of fluid jetting holes of said first fluid jetting hole series and said plurality of fluid jetting holes of said second fluid jetting hole series to produce, in said superposed fiber bundle portion, two or more interlaced fiber portions in which said fibers are interlaced and that are located apart from each other in the length direction of the fiber bundles and an unraveled fiber portion in which said fibers are unraveled and that is located between said two or more interlaced fiber portions, in such a manner that each of said interlaced fiber portions is composed of two or more interlaced sub-portions that are composed of said multiple fibers of one fiber bundle and said multiple fibers of the other fiber bundle interlaced in said superposed fiber bundle portion and that are located at intervals in the width direction of said fiber bundles, so that said fiber bundles are joined together in said superposed fiber bundle portion. 
     
     
         9 . The production method for a fiber bundle according to  claim 8 , wherein both said first fiber bundle and said second fiber bundle are a precursor fiber bundle designed for carbon fiber production. 
     
     
         10 . The production method for a fiber bundle according to  claim 9 , wherein said joint fiber bundle has a heat conductivity of 3 to 700 W/m·K. 
     
     
         11 . The production method for a fiber bundle according to  claim 10 , wherein said joint fiber bundle is a carbon fiber bundle having a drape value of 2 to 15 cm and a flatness of 20 or more. 
     
     
         12 . The production method for a fiber bundle according to  claim 11 , wherein the fineness of said joint fiber bundle is 0.2 to 3.0 times that of said first fiber bundle and that of said second fiber bundle. 
     
     
         13 . The production method for a fiber bundle according to  claim 11 , wherein said fiber joint portion has a tensile strength of 20 g/tex or more at room temperature. 
     
     
         14 . The production method for a fiber bundle according to  claim 8 , wherein said first line and said second line are separated by 20 to 100 mm, and the fluid jetting holes in said first fluid jetting hole series and said second fluid jetting hole series a re aligned at intervals of 1.7 to 4.5. 
     
     
         15 . A carbon fiber production method comprising a step of passing a fiber bundle as set forth in  claim 4  continuously through an oxidizing furnace and then a carbonizing furnace to produce a carbon fiber.