Process for fabricating tough polyethylene terephthalate articles with low gas and organic liquid permeability

Claim 1

In a process for melt-fabricating articles from blends of 45-95 weight percent of polyethylene terephthalate with 5-55 weight percent of a toughening polymer selected from (a) copolymers of at least 70 weight % of an alpha-olefin having 2-5 carbon atoms with at most 30 weight % of an alpha, beta-unsaturated carboxylic acid, (b) copolymers of ethylene with an alpha, beta-unsaturated carboxylic acid and a third ethylenically unsaturated monomer, their respective weight ratios in the polymer being 40-95%, 0.5-20%, and 10-40%; (c) ionomers obtained by a complete or partial neutralization of a copolymer of paragraph (a) or (b) with zinc or magnesium ions, and (d) an E/X/Y copolymer, where the monomers E, X, and Y are as follows: E is ethylene and comprises 40-90 weight percent of the ethylene copolymer; X is a carboxylic ester represented by the formula where R₁ is an alkyl group with 2-8 carbon atoms; and R₂ is H, CH₃, or C₂H₅; and X comprises 10-40 weight percent of the E/X/Y copolymer; and Y is selected from the group consisting of glycidyl methacrylate and glycidyl acrylate, and Y comprises 0.5-20 weight percent of the E/X/Y copolymer, said blends containing 0-10% based on the total polymer weight of a finely ground, non-nucleating filler, the improvement of conducting the melt-fabrication under conditions minimizing polyethylene terephthalate crystallization, preferably in the absence of a nucleating agent, and preferably keeping the surfaces of melt-fabricating equipment in contact with the polymer blend below 100⁰C, and especially below 50⁰C, whereby a tough article having low permeability to gases and to organic liquids selected from the class consisting of aliphatic and aromatic hydrocarbons, ketones, alcohols, ethers, and esters is obtained.