Method for cleaning molding machine in which residual thermoplastic resins remain and cleaning composition therefor

摘要

A method for cleaning the interior of a molding machine having a residual thermoplastic resin after molding comprises the step of cleaning the interior of a molding machine with a cleaning composition which comprises: (A) 100 parts by weight of a thermoplastic resin; (B) 2 to 100 parts by weight of a polyalkylene oxide glycol having a viscosity-average molecular weight ranging from 10,000 to 1,500,000; and (C) 0.5 to 5 parts by weight, per 100 parts by weight of the sum of the foregoing components (A) and (B), of an alkylsulfate represented by the following general formula (I): R1-O-SO3M(I) wherein R1 represents an alkyl group having 8 to 20 carbon atoms and M represents an ion selected from the group consisting of K, Na and NH4 or a fatty acid salt represented by the following general formula (II): R2COOX(II) wherein R2 represents an alkyl group having 7 to 23 carbon atoms and X represents an ion selected from the group consisting of K, Na, Ca, Mg and Zn. The cleaning method exhibits excellent properties of cleaning molding machines and makes it possible to perform rapid exchange of colors and/or kinds of resins within a single molding machine.