| 摘要 |
PURPOSE:To make a base film having both excellent security characteristics and print transferring property obtainable by laminating a polyester outer layer for specifying the density on both surfaces of a polyester inner layer being predetermined in its density. CONSTITUTION:For example, an ordinary polyester is applied as a material for forming a larger film layer than an inner layer, namely, including almost no closed cells and with the density of 1.30g/cm<3>. On the other hand, polyester blended with specific polypropylene and/or polymethylpentene of 3-40wt.% is applied as a material for forming a film layer which is an outer layer, namely, containing an innumerable closed cells and in the range of 0.40-1.30g/cm<3> in its density. Each polyester is melted and kneaded by individual extruders, and then supplied to a T die through a conduit, further, extruded into a slit shape after being laminated in a melted condition for forming an outer layer on both surfaces of an inner layer, wherein both inner layer and outer layer are made in a substantially amorphous laminate sheet. |
