Opaque films with a thickness of from 10 to 500 μm are well known.
The object of the present invention was to provide an opaque, white film with a thickness of from 10 to 500 μm which, besides having good orientability, good mechanical properties and good optical properties and a low Yellowness Index, above all has high whiteness and low transparency.
The good optical properties include uniform, streak-free coloration over the entire length and width of the film, low luminous transmittance/transparency (≦30%), acceptable surface gloss (≧10), and also a low Yellowness Index (dependent on thickness, ≦45 for 250 μm films and ≦20 for 50 μm films).
The good mechanical properties include a high modulus of elasticity (EMD≧3300 N/mm2; ETD≧4200 N/mm2), and also good tear strengths (in MD≧120 N/mm2; in TD≧170 N/mm2) and good longitudinal and transverse elongations at break (in MD≧120%; in TD≧50%).
Good orientability includes excellent capabilities of the film for orientation during its production, both longitudinally and transversely, without break-offs. The novel film should moreover be recyclable, that is to say that any cut material arising during continuous film production can be fed back into the production operation as regrind, in particular without loss of optical or mechanical properties from the film, so that it can still be used for interior applications and in constructing exhibition stands, for example.
USPTO Backgrounds
USPTO Backgrounds