Reinforced poly(ethylene terephthalate) compositions

Claim 1

A process for thermoforming an article from a sheet of a composition having a crystallinity of 0-5% and consisting essentially of the following components in stated approximate weight proportions: (a) 60-77% of poly(ethylene terephthalate) having an inherent viscosity of more than 0.55 dL/g; (b) 3-10% of at least one terpolymer of ethylene selected from the class consisting of ethylene/methacrylic acid/isobutyl acrylate terpolymer, ethylene/methacrylic acid/n-butyl acrylate terpolymer, and ethylene/vinyl acetate/methacrylic acid terpolymer, the respective proportions of methacrylic acid and of isobutyl acrylate, n-butyl acrylate, or vinyl acetate in the terpolymer being about 1 to 30 weight percent of each; said terpolymer having 0-100% of its carboxylic groups converted to their salt form, the cation being a divalent metal ion; with the first proviso that up to about 20% of the recited component (a) can be replaced by a polymer compatible with poly(ethylene terephthalate) and selected from the class consisting of polyesters, polyamides, and polycarbonates; and (c) 20-30% of a reinforcing material having an aspect ratio of at least 10%; with a second proviso that the composition does not contain nucleating agents; the process comprising the following steps: (A) placing the sheet in a single mold maintained at a temperature of about 140°-150° C., (B) applying a vacuum of about 8 kPa to one side of the sheet, while a pressure of about 690-5520 kPa is applied to the other side of the sheet, to cause the sheet to deform and collapse onto the mold, thus conforming its shape to that of the mold, (C) releasing the vacuum and the pressure, and (D) removing the resulting molded article from the mold.