| 摘要 |
PURPOSE:To enable drying in a short time by preventing fusing of polyester particles, by a method wherein at the time of the drying of the particles by microwaves, a water content of a surface layer part and inner layer part is specified. CONSTITUTION:Polyester is of polyethylene terephthalate and that consisting mainly of the polyethylene terephthalate and even a matter where a part of a terephthalic acid ingredient or a glycol ingredient is replaced by the other copolymeric ingredient may be good. It is necessary that water content of a surface layer part, which is less than 300mum from the surface is made at least 0.8wt.% and not exceeding 5wt.% and further water content of the central part (inner layer part) which is at least 300mum from the surface is made not exceeding 0.5wt.%, in a distribution of a containing water in polyester particles which is prior to irradiation of microwaves. Then the shortest diameter of the particles is made at least 1mm, preferably at least 1.5mm, in a particle form of a polyester resin and the microwave to be used for drying is of an electromagnetic wave where it is at least UHF zone in an electric wave classification and possesses frequency of 1-100GHz sphere, especially the microwaves of 2.45+ or -0.05GHz are favorable. |
