| 摘要 |
PURPOSE:To obtain polyester resin containing small acetaldehyde content without problem of sanitation by a simple method by regulating water content of the resin containing ethylene terephthalate unit as a main ingredient to a specific value, and melting, molding it. CONSTITUTION:In order to melt and mold polyester resin containing ethylene terephthalate unit as a main ingredient, water content of the resin is regulated to 60-500ppm, and the resin is melted and molded. A water content regulating method is executed by an apparatus having a moisture meter in the step of drying before melting and molding, and drying is finished when predetermined water content is obtained. As another method, there are a method having the steps of once lowering water content in polymer to 50ppm or less, then regulating its moisture and regulating the content. Drying is executed by various dryer. A moisture absorbing method is executed by a method for absorbing moisture in a constant-temperature and constant-moisture machine or a constant- temperature and constant-moisture chamber or a method having the steps of adding moisture to resin to be mixed and absorbing it in a chip. |
