Coated plastic substrate manufacture, in particular PET container with barrier coating, involves stretching substrate in specific temperature range to give irreversible plastic deformation before plasma coating stage

摘要

A substrate is manufactured by plastic deformation of a thermoplastic plastic. The substrate is then preconditioned by applying a stress to effect rapid stretching at a temperature(TE) in the softening range of the thermoplastic. A stress to extension ratio(E) is set at a level which ensures that at least part of the extension is plastic and therefore non-reversible. A thin functional layer is then applied to the substrate by a plasma supported coating method. A substrate in the form of a container, in particular a PET (polyethyleneterephthalate) bottle, is produced by a extrusion and/or injection and/or blow molding. Prior to coating the container is stretched by a uniformly applied sudden pressure(p e) of 1-20 bar on the inner surface. The stress to extension ratio(E) is set at a level which produces a plastic and irreversible extension of 1-15% in at least one local area. Temperature(TE) during pressure application is 40-70[deg]C., preferably 40-60[deg]C and more preferably 50[deg]C. Applied pressure(p e) is 4-10 bar, more preferably 6 bar and plastic extension 3-8%, preferably 5%. Coatings may be applied internally and/or externally. Coatings may be applied by: a) a plasma supported PVD process (physical vapor deposition), preferably sputtering or b) a CVD process (chemical vapor deposition), preferably PICVD (plasma impulse chemical vapor deposition). For better adhesion between substrate and functional layer the coating method involves activating the surface to be coated by pretreatment with an oxygen plasma. Functional layers may comprise one or more barrier layers which also act as adhesion coupling layers. Additional process gas used during plasma coating include nitrogen and oxygen. Alternative forms of substrate include strip or film materials which can be stretch blown and/or extruded and/or calendered. An independent claim is included for a coated substrate comprising a thermoplastic plastic substrate preconditioned by plastic stretching and a thin functional layer applied by a plasma supported method.