Patent ID: 8883947

Claim:
A vinylidene fluoride homopolymer represented by the formula (4): CF 3 -(A 1 )-I (4) wherein A 1 represents a structural unit of vinylidene fluoride homopolymer which comprises crystal form I alone or as main component and has a number average degree of polymerization of 5 to 12, wherein the vinylidene fluoride homopolymer comprises crystal form I alone or as main component and when attention is given to proportions of the respective vinylidene fluoride homopolymers having crystal form I, II or III which are calculated by IR analysis, the proportion of vinylidene fluoride homopolymers having crystal form I satisfies both of (Equation 3): 100≧I-form/(I-form+II-form)≧70% by weight (Equation 3) and (Equation 4): 100≧I-form/(I-form+III-form)≧70% by weight (Equation 4).