JPS55112282A - Manufacture of pencil core - Google Patents

Abstract

PURPOSE: To manufacture a pencil core excellent in strength, color deepness, and writability by the procedure in which a diluted hardener solution, an uncured furan resin, a vinyl acetate resin, a specific chloride, a colorant, and a wax are mixed, molded, hardened under a specific condition, and then baked.

CONSTITUTION: A pencil core composition is obtained by mixing 100pts.wt. of uncured furan resin (A) of a molecular weight of 100W800, 40 or less pts.wt. of a vinyl acetate resin (B) of a number-average molecular weight of 5000W300,000, 40 or less pts.wt. (on the basis of 100pts.wt. of (B)) of a chloride (C) of a higher aliphatic hydrocarbon or a higher fatty acid ester, containing 25W80wt% chlorine, 50W40pts.wt. of a colorant (D), e.g., graphite, MoS₂, etc., and 4W50pts.wt. of a wax (E) of melting point of 45°C or more, e.g., Japan wax, stearic acid, etc., and then the composition thus obtained is mixed with 0.2W7pts.wt. (on the basis of 100 pts.wt. of (A)) of a 10-to 200-wt fold-diluted hardener solution and then molded into a pencil core shape. Then, the molding is hardened at 110°C or less until a hardening degree of 70% or more is reached and then baked at 900°C or more for 4W8hr. in a non-oxidative atmosphere.

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