Process for the Production of Coated Polymeric Film
May 6, 2008
A heat-sealable polymeric film was patented. It comprises an oriented substrate layer of polymeric material with a heat-sealable coating layer on its surface. This consists of a copolyester and, optionally, one or more additives. The copolyester consists of repeat units of one or more aliphatic dicarboxylic acids, one or more aromatic dicarboxylic acids selected from the group consisting of terephthalic acid, isophthalic acid and phthalic acid, and a stoichiometric amount of a glycol component consisting of one or more glycols selected from the group consisting of aliphatic glycols and cycloaliphatic glycols. The coating layer is less than about eight microns in thickness.
The one or more additives are selected from the group consisting of cross-linking agents, dyes, pigments, lubricants, anti-oxidants, radical scavengers, UV absorbers, thermal stabilizers, anti-blocking agents, surface active agents, slip aids, optical brighteners, gloss improvers, prodegradents, viscosity modifiers, dispersion stabilizers and particulate inorganic fillers. The heat-sealable polymeric film is peelable and the concentration of one or more aromatic dicarboxylic acids in the copolyester is in the range from 40 to 70 mol % based on all the dicarboxylic acid components of the copolyester. The concentration of one or more aliphatic dicarboxylic acids in the copolyester is in the range from 30 to 60 mol % based on all the dicarboxylic acid components of the copolyester.