Blow moulding polyethylene terephthalate parisons - by first coating heated parison with vinylidene chloride aqs. dispersion and drying

摘要

Biaxially oriented containers are produced by coating an amorphous polyethylene terephthalate parsion with a vinylidene chloride copolymer (I) and axially and radially drawing the parison by blow-moulding. The improvement comprises coating the parison while it is at 40-80 degrees C, pref. 50-70 degrees C, with an aqs. dispersion of the copolymer and drying the coating prior to blow moulding. Pref. the surface of the parison is treated with a solvent (e.g. butanone) to induce crystallisation on the surface before applying the coating. Process is partic. for prodn. of bottles for carbonated drinks, Heating the parison prior to coating enables formation of an adherent and uniform coating 20-30 u thick in only one application. The (I) coating improves the impermeability of the containers w.r.t. CO2 and O2.