| 摘要 |
PROBLEM TO BE SOLVED: To stabilize film formation while a life of a filter is remarkably prolonged by using a metal powder sintered filter wherein a sieve opening of the filter is successively decreased in the order from the initial filtration process, and in the last filtration process, a sieve opening larger than that in the preceeding process is provided. SOLUTION: Polyester resin is extruded by melting with an extruding machine, and the molten resin is successively filtered with a filter consisting of metal powder sintered compact of a large sive opening on the first stage, a filter consisting of metal fiber sintered compact wherein the sieve opening is the minimum and filter precision is 10μm or under on the second stage, and a filter consisting of the metal powder sintered compact of a large sieve opening lastly. For the filter in this case, molten resin from, for example, the extruding machine 1 is filtered by using three or more kinds of filters 2, 3, 4. The filtered molten resin is discharged in a sheet state from a mouthpiece. A resin sheet is solidified by cooling with a cooling rotor 12 to become a polyester resin sheet 6. |
