| 摘要 |
PURPOSE:To improve durability by constituting a protective film of the films having the multi-layered structure in which the film having relatively small compactness and internal stress is sandwiched by the films having the relatively larger characteristics thereof. CONSTITUTION:The protective film 8 made into the integrated structure of the three layers, a recording film 3, an interference film 4, a reflection films 5 and a single-layered protective film 6 are laminated on a substrate 1a made of a synthetic resin. Such substrate is stuck by an adhesive layer 7 to another substrate 1b. The films 8a and 8c sandwiching the film 8b are required to be denser and larger in the internal stress (compressive stress) than the film 8b. The values of the internal stress are preferably so adjusted that the value of the film 8b is larger than the certain value within a 40-50kg/mm<2> as a boundary and that the value of the films 8a and 8c is smaller than said value. The difference between the two values is preferably adjusted to >=20kg/mm<2>. The compactness of the film can be defined by the density of the film expressed in terms of a ratio to the bulk density. The films 8a, 8c having the relatively higher compactness have preferably 1.0-0.90 values thereof.
|
