PURPOSE: To obtain a production of double thermoplastic polyester resin laminate steel plate superior in adhesion and processability.
CONSTITUTION: A thermoplastic polyester resin is laminated on each surface of a steel plate 2 by a T-die extrusion method. In the T-die extrusion laminate process, the resin is laminated on one surface by a part 5 after the resin is laminated on the other surface by a part 4 and, at this time, the temperature of the steel plate is set to be from 100 to 150°C. The obtained double laminate steel plate is again heated by a part 6 at a temperature from 160-230°C for a time from 2 to 20 sec and immediately cooled by a part 7. In this manner, by conducting the second laminate process at a temperature of 150°C or lower, the thermoplastic polyester resin film laminated in the first process is prevented from being flawed by a rear-surface roll during the second laminate process. By again heating the laminate after the double laminate process, the adhesion of the laminate film with the steel plate is improved.
YOSHIHARA RYOICHI
TAKANO KOJIRO
