Heat-Set PET Bottles At Very High Rates.

PET bottles that withstand pasteurization temperatures of 167 F for 40 min are said to be produced at rates of 30,000 bottles/hr with a new reheat stretch-blow-molding system in development by Toyo Seikan of Japan. Called "S-Cosmos," it stretches and heat-sets the bottom and sidewall of 500-cc bottles. This improves resistance to heat and internal gas pressure and reportedly can reduce bottle weight by 20%. When combined with a barrier coating, the bottles are said to be suitable for pasteurized beer. (An earlier version of the process, called Cosmos, produced 1.5L bottles that were less highly stretched and heat-set.)

The S-Cosmos process involves two blowing stages. The first stage completely stretches the bottom of the bottle, raising bottom and sidewall crystallinity to 40-50%. Then the bottle enters a heat-setting oven and is selectively heated around the bottom. Next, the bottle is transferred to a second mold and blow molded to its final shape. A paper on this development was presented at last month's Nova-Pack Americas 2000 conference in Orlando, Fla., sponsored by Schotland Business Research, Skillman, N.J.