Bobbin, method of producing the bobbin, and method of producing fiber-reinforced plastic

Abstract

A bobbin includes a reinforcing fiber bundle formed in a wound shape, and the reinforcing fiber bundle is formed of a plurality of filaments. The reinforcing fiber bundle includes a first twist having a first value T1 per unit length (turn/m) at a first distance r1 from a center axis of the bobbin, a second twist having a second value T2 per unit length (turn/m) at a second distance r2 from the center axis of the bobbin, and a third twist having a third value T3 per unit length (turn/m) at a third distance r3 from the center axis of the bobbin; said reinforcing fiber bundle is disposed so that the following relations are concurrently satisfied: |T1/2πr1|≧|T2/2πr2|≧|T3/2πr3| |T1/2πr1|>|T3/2πr3| |T1|≧|T2|≧|T3|≧0.5 where the first distance r1, the second distance r2, and the third distance r3 are different from each other (r1≠r2≠r3).

Dependencies are inferred from the claim text.