Patent ID: 9657413
Date: 2017-05-23
CPC Classifications: D01F

Claim:
1. A continuous carbonization method comprising passing a continuous, oxidized polyacrylonitrile (PAN) precursor fiber through a carbonization system, said carbonization system comprising: a) a first drive stand comprising a series of drive rollers rotating at a first speed (V1); b) a pre-carbonization furnace configured to contain inert gas and supply heat within a temperature range of about 300° C. to about 700° C.; c) a carbonization furnace configured to contain inert gas and supply heat at a temperature range of about 800° C. to about 2800° C.; d) a first substantially air-tight chamber located between and connected to the pre-carbonization furnace and the carbonization furnace such that no air from surrounding atmosphere can enter into the pre-carbonization furnace, the carbonization furnace or the air-tight chamber; e) a second drive stand comprising a series of drive rollers rotating at a second speed (V2) which is greater than or equal to V1 (or V2≧V1), the second drive being positioned between the pre-carbonization furnace and the carbonization furnace, and the drive rollers of the second drive stand are enclosed by said air-tight chamber, wherein the oxidized PAN fiber makes direct wrapping contact with the rollers of the first drive stand prior to entering the pre-carbonization furnace, and the precursor fiber exiting the pre-carbonization furnace then makes direct wrapping contact with the rollers of the second drive stand prior to entering the carbonization furnace, and wherein the fiber exiting the carbonization furnace is a carbonized fiber which has been exposed to an atmosphere comprising 5% or less by volume of oxygen during its passage from the pre-carbonization furnace to the carbonization furnace.