| 摘要 |
PROBLEM TO BE SOLVED: To provide a plastic sheet characterized by: having no concern about deterioration of folding lines or degradation of strength even if the portions folded along the folding lines are irradiated with a light for a long period of time; being easy to fold along the lines because a recessed groove forming the folding line is formed with uniform depth; and enabling to keep the shape of the folded portions even if the depth of the recessed groove composing the folding line is not so deep in the case of a sheet material with high elasticity. SOLUTION: The portions to be folded in a plastic sheet 10 are pressed to form the thinned strips, and the thinned strip parts 14 are compressed linearly to form the folding lines 12. COPYRIGHT: (C)2008,JPO&INPIT |
