Patent ID: 9157172
Filing Date: 2015-10-13
Classification: B65H,D01F

Abstract:
1. A method for producing carbon fiber bundles, comprising: a flame-retarding step of converting a plurality of precursor fiber bundles into flame-retardant fiber bundles by heat treating the plurality of precursor fiber bundles in an oxidizing gas atmosphere at from 200 to 300° C. in a state that the plurality of precursor fiber bundles are lined up side by side in parallel to each other; a precarbonization step of converting the flame-retardant fiber bundles into precarbonization-treated fiber bundles by heat treating the flame-retardant fiber bundles in an inert gas atmosphere with the highest treatment temperature of from 500 to 800° C. in a state that the flame-retardant fiber bundles are lined up side by side in parallel to each other; and a carbonization step of converting the precarbonization-treated fiber bundles into carbon fiber bundles by heat treating the precarbonization-treated fiber bundles in an inert gas atmosphere with the highest treatment temperature of 1000° C. or higher in a state that the precarbonization-treated fiber bundles are lined up side by side in parallel to each other, wherein when a traveling pitch of the fiber bundles in the flame-retarding step is represented by P