| 摘要 |
PROBLEM TO BE SOLVED: To provide excellent scratch resistance by forming a film so that the elastic deformation quantity in the total deformation quantity at a time when push-in deformation is applied to a surface becomes a specific ratio. SOLUTION: Polyethylene-2,6-naphthalate is dried under vacuum to be extruded from a T-die in a molten state. This extrudate is closely bonded to a cooling drum while static electricity is applied to the drum to be cooled and solidified to obtain an unstretched web. Thereafter, steam spraying treatment is applied to both surfaces of the web and, succeedingly, this unstretched web is stretched by 3.3 times in its longitudinal direction by a roll type longitudinal stretching machine. Further, this web is stretched by a tenter type lateral stretching machine so that lateral stretching magnification is 3.3 times. Subsequently, the web is heat-treated and further thermally fixed in a thermal fixing zone. The web is gradually cooled while slackened by 5% laterally to be taken up to obtain a film with a thickness of 85μm. This film is further heat-treated at 110 deg.C for 48 hr. In this film, the ratio of the elastic deformation quantity of the total deformation quantity at a time when push-in deformation is applied, to the surface of the film is 60% or more, that is, 64%.
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