Mesophase pitch for use in the making of carbon materials

Abstract

Pitch that is obtained from naphthalene derivatives having at least one methyl group and the content of an optically anisotropic phase in which is substantially 100% is disclosed. This mesophase pitch has a H/C atomic ratio of about 0.5-1.0 and an aromatic carbon ratio (fa) of at least about 0.7, contains methylic carbon in an amount of at least about 4% of the total carbon atoms, and has a softening point of 200.degree.-250.degree. C. The pitch contains about 12-20 mole % of molecules having an average molecular weight of less than about 600, about 55-70 mole % of molecules having an average molecular weight of from about 600-1,500 and about 20-30 mole % of molecules having an average molecular weight of higher than about 1,500. Fibers melt spun from this mesophase pitch can be converted to carbon or graphite fibers having high strength and modulus of elasticity by a heat treatment which consists of heating to a temperature of 200.degree.-350.degree. C. in an air atmosphere, then heating to about 1,000.degree. C. or higher in an inert gas atmosphere. Such mesophase pitch is produced by polymerizing a naphthalene derivative having at least one methyl group for about 5-300 minutes at a temperature of about 180.degree.-400.degree. C. and at a pressure of about 5-100 atmosphere in the presence of about 0.1-20 moles of HF and about 0.05-1.0 mole of BF.sub.3 per mole of the naphthalene derivative.