To obtain the subject cleaning agent by using a hydrogenated biphenyl or hydrogenated terphenyl compound so as to be capable of efficiently, nearly entirely cleaning molds used for molding polyester resins of deposits adhered onto the molds.
This cleaning agent for molds used for molding polyester resins (e.g. predominant in polyester resins with ethylene terephthalate unit as the major repeating unit) is such one as to use (A) a hydrogenated biphenyl compound such as cyclohexylbenzene or bicyclohexy or (B) a hydrogenated terphenyl compound such as a mixture of terphenyl isomer's partially hydrogenated compounds. The cleaning agent exhibits the high ability to dissolve polyester oligomers such as ethylene terephthalate cyclic trimer as mold deposits, can efficiently remove mold deposits, and furthermore, because of having a high boiling point, can clean high-temperature molds without cooling.
SONODA HIROTOSHI
KIMURA OSATAKE
ETO YOSHITAKA
