PURPOSE: To efficiently clean and remove the residual resin within the heating cylinder of a resin molding machine in short time, and moreover, enable the cleaning agent to be removed efficiency by the resin material to be molded subsequently by constituting the title agent of a polymer of methyl methacrylate and acrylic ester, and making the melt index of the polymer and the rate of weight reduction as heated in the atmosphere of nitrogen exist in a specific range.
CONSTITUTION: The cleaning agent is a polymer consisting of 100-85wt.% of methyl methacrylate and 0-15wt.% of acrylic ester, and the melt index measured at 230°C, 10kg is in the range of 0.05-2.0g/min., and then the rate of weight reduction as heated at 280°C, 20min, is 3-40%. Namely, the cleaning agent acts to remove the residual resin within the heating cylinder as being in the form of high melt viscosity, and next, in the stage of removing the cleaning agent by the resin material to be molded subsequently, the heat decompositing property acts effectively, and thus the melt viscosity of the cleaning agent is lowered, thereby enabling the cleaning agent to be removed readily by the resin material.
SOGA MASAHIRO
KISHIMURA MASAAKI
