초록 ▼

This relates to the heating of polyethylene terephthalate by way of RF energy. It has been found that if polyethylene terephthalate articles are passed through a radio frequency energy field, the molecules thereof will become excited and rapid heating will result. This heating is particularly useful

This relates to the heating of polyethylene terephthalate by way of RF energy. It has been found that if polyethylene terephthalate articles are passed through a radio frequency energy field, the molecules thereof will become excited and rapid heating will result. This heating is particularly useful in the heating of preforms prior to the blow molding thereof and by varying the configuration and relationship of electrodes, controlled heating of the preforms may be effected with it being possible to have a controlled temperature differential along the length of the preform or other article so heated.

대표청구항 ▼

A method of rapidly heating a tubular preform formed of polyethylene terephthalate substantially uniformly for the full thickness of the wall thereof, said preform being of the type including a neck finish and a body portion terminating in a closed end and said method comprising the steps of support

A method of rapidly heating a tubular preform formed of polyethylene terephthalate substantially uniformly for the full thickness of the wall thereof, said preform being of the type including a neck finish and a body portion terminating in a closed end and said method comprising the steps of supporting a preform formed of polyethylene terephthalate by its neck finish and while rotating the preform about its axis generating between a pair of electrodes a radio frequency field within the range of 13 to 98 megahertz and subjecting the body portion and closed end to said radio frequency field for a period of time of 29 seconds or less to increase the temperature of the preform body and closed end to a thermoforming temperature.