To provide a method for manufacturing a biaxially oriented polyester film for a melting-type thermal transfer recording material superior in ink transferring properties.
The method for manufacturing the biaxially oriented polyester film for the thermal transfer recording material comprises melt-extruding a polyester, performing a first step drawing of a sheet solidified on a cooling roll at first in the transverse direction, heat-treating it under a fixed length in the width direction, performing a second step drawing in the longitudinal direction, performing heat fixing treatment at 140-230°C under a fixed length in the width direction, and furthermore, performing a relaxation treatment of 1-8% in the width direction at 140-230°C. The method for manufacturing the biaxially oriented polyester film for the thermal transfer recording material, is characterized in that the heat treatment between the first step transverse drawing and the second step longitudinal drawing is performed for 0.5-3 seconds at a temperature between the glass transition temperature of the polyester and the glass transition temperature+20°C, to make the maximum height (Rt) on the film surface to be 5.0-7.0 μm.
HASHIMOTO YOSHIHARU
MATSUOKA MIKIO
SUMINO HIROSHI
KADA SUKEKI
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