초록 ▼

An improved PET process, system and container which uses an improved single stage process to produce a thermally stable container. The single stage process arrests the cooling of the preform at elevated temperatures followed by equilibriation to a set temperature in a conditioning station at control

An improved PET process, system and container which uses an improved single stage process to produce a thermally stable container. The single stage process arrests the cooling of the preform at elevated temperatures followed by equilibriation to a set temperature in a conditioning station at controlled time rates to achieve high crystallinity in the container side wall. Special provisions are made for establishing a transition zone temperature gradient adjacent the container mouth to achieve high crystallization in the transition zone. The container is especially configured in a number of instances to make it suitable for hot fill applications. One such instance includes rigidizing the body side wall against radial and longitudinal vacuum distortion so that paper labels can be applied to the container.

대표청구항 ▼

A one stage process for forming from PET material and in the absence of a heat set step, a PET container for use in hot fill applications comprising the sequential steps of: (a) drying said PET material to a moisture content of less than about 0.02% by weight and maintaining said PET material such t

A one stage process for forming from PET material and in the absence of a heat set step, a PET container for use in hot fill applications comprising the sequential steps of: (a) drying said PET material to a moisture content of less than about 0.02% by weight and maintaining said PET material such that its dew point is less than about minus 35°F. in an enclosed space; (b) plasticizing said PET material while said PET material is maintained at said moisture content less than about 0.02% by weight. (c) injecting or extruding at an initial temperature of about 520°F. to 550°F., said PET material in the dried plasticized form into a preform mold to form a preform of a hollow, generally cylindrical configuration with a closed end and having wall sections between interior and exterior surfaces of predetermined wall thicknesses along the length thereof, and rapidly cooling said PET material in said preform mold at a rate sufficiently fast to prevent spherulite growth but sufficiently long in duration to permit adding additional PET material to said mold to compensate for volumetric contraction of said PET material; (d) transferring said preform from said preform mold to a conditioning station when the surface temperature of said preform has been cooled in said preform mold to about 230°F. to 260°F.; (e) equilibriating the temperature through the wall sections of said preform in said conditioning station to a substantially uniform temperature between about 210°F. to 230°F. over a time period sufficient to develop a crystallite formation; and (f) stretching and blow molding said preform in a blow mold into a desired container shape, said stretching and blowing commencing when said preform is at said temperature of about 210°F. to 230°F. and completed when the temperature of said container is about 50°F. to 150°F. whereby a thermally stable container with a haze transmission of less than about 5% throughout and a crystallite formation of at least about 30% is produced; said container having a shrinkage of no greater than 2 to 5% in any dimension when hot filled with products at about 195°F. in a hot fill process where said container is sealed within about 5 to about 15 seconds from the time it is hot filled.