Method for producing combined yarn bundle and method for producing carbon fiber using the obtained combined yarn bundle

摘要

Two or more carbon fiber precursor yarns that run substantially parallel to each other are brought into contact with the first roller (1), and then the two or more carbon fiber precursor yarns are divided into two to form a pair of second rollers. The carbon fiber precursor yarn is rotated by approximately 90 ° between the first roller (1) and the pair of second rollers (2, 2 ′) by contacting with (2, 2 ′), respectively, The carbon fiber precursor yarns coming out of the second roller (2) of the second roller are sequentially brought into contact with the third front roller (3) and the third rear roller (3 ′), and from the other second roller (2 ′). The carbon fiber precursor yarn that has come out is brought into contact with the third rear roller (3 ′) without being brought into contact with the third front roller (3), and these carbon fiber precursor yarns are placed on the third rear roller (3 ′). Combine the yarn, and then the carbon fiber precursor yarn coming out of the third rear roller (3 ′) 4 is brought into contact with the rollers (4), to obtain a doubling yarn bundle. The ratio between the distance L between the axes of the first roller (1) and the pair of second rollers (2, 2 ') and the average value of the yarn width W of the carbon fiber precursor yarn on the first roller, L / W is 18 or more, and the tension of the combined yarn bundle after coming out of the fourth roller is 0.11 cN / dtex or more.