INJECTION MOLDING METHOD OF METHACRYLATE RESIN

PURPOSE:To reduce a quantity of a carbonized foreign matter as compared with conventional molding of methacrylate resin, by a method wherein methacrylate resin is heated and melted under inert gas atmosphere including inert gas at a specific volumetric ratio or more, in injection molding of the methacrylate resin. CONSTITUTION:At least 95 capacity % of atmosphere of an air gas part of a cylinder or a hopper of a molding machine is replaced with inert gas. A reason why a volume possessory ratio of an air gap is made into at least 95 capacity % is that since a carbonized foreign matter is generated and yield is lowered when the same is less than the 95 capacity %, far preferably at least 99 capacity %. Although nitrogen, helium, carbon dioxide and argon are mentioned as using inert gas, the nitrogen is effective from a view point of a cost.