Coating hollow containers by in-situ polymerization of monomers in bi-axially orientated form

Abstract

Methods for providing a low permeability coating on the interior of a refillable plastic container, such as a PET beverage bottle, include coating of a liquid crystal polymer (LCP) by depositing LCP monomers on the interior surface of the container and bi-axially orienting the monomers continuously while reacting the monomers to produce the polymer. The interior surface of the container may be pre-treated to produce free radicals which enhance the attachment of the monomers to the surface. Also, the surface may be post-treated to eliminate unsaturated radicals or free monomers. The application of the monomers to the interior surface of the container can be effected by condensing a gas blend of monomers, by spraying liquid monomers or by filling with liquid monomers and then emptying to leave a residual coating. The monomers are reacted by preheating them or by subjecting them to a heated inert gas. To achieve the bi-axial orientation of the monomers, the interiorly coated container may be alternately subjected to longitudinal and circumferential magnetic fields while supported for incremental end-to-end rotation and rotation about its axis. Another technique for achieving the bi-axial orientation comprises subjecting the container to alternately applied longitudinal and circumferential electrostatic fields.

Dependencies are inferred from the claim text.