| 摘要 |
<p>A single sided, sealable biaxially oriented coextruded polyester film having at least one base layer (B) containing at least 80 wt.% thermoplastic polyester, a sealable top layer (A), and a matt top layer (C), where: (a) layer A has a starting sealing temperature of less than 120 deg C, a seal seam strength of at least 1.0 N/25 mm of film width, a maximum Ra value of 100 nm, and a surface gas flow measurement value of 20-4000 s is new. A single sided, sealable biaxially oriented coextruded polyester film having at least one base layer (B) containing at least 80 wt.% thermoplastic polyester, a sealable top layer (A), and a matt top layer (C), where: (a) layer A has a starting sealing temperature of less than 120 deg C, a seal seam strength of at least 1.0 N/25 mm of film width, a maximum Ra value of 100 nm, and a surface gas flow measurement value of 20-4000 s; (b) the matt top layer C has a maximum glaze of 100, a minimum Ra value of 150 nm, and a surface gas flow measurement value of 0-80 s; and (c) ess than 50% turbidity. An Independent claim is also included for: preparation of the film by coextrusion, where the individual A, B, and C layers of polymer or polymer mixture are compressed and liquefied in an extruder, if necessary with addition of additives, pressing of the melt simultaneously through a flat nozzle, feeding of the multilayer melt to one or more rollers, with cooling of the melt and fixing of the melt to a prefilm, which is biaxially prestretched, heat fixed, and, if necessary, corona or flame treated. The film is stretched longitudinally at 80-130 deg C, and transversely at 90-150 deg C, at a preferred longitudinal stretching ratio of 3:1 to 5,5:1, and a preferred transverse stretching ratio of 3.5:1 to 4.5:1.</p> |
