Tetra Pak Introduces Two New PET Barrier Technologies
The first technology is Glaskin, a proprietary technology that coats the inside of blown PET bottles with a thin crystal-clear glass-like layer of silicon oxide (SiOx) and is said to provide superb gas-barrier characteristics and flavor retention performance. In customer shelf-life tests Glaskin coating has shown excellent oxygen and carbon dioxide barrier properties, and, because it is inert in contact with food, the potential for scalping and flavor absorption are reduced. Customer shelf-life requirements, depending on products and countries, have ranged from four to 12 months.
Glaskin comprises numerous proprietary processes, materials and designs. The new technology produces uniform barrier PET bottles in sizes from 0.2 to 2-L. Currently, coating speeds of 6,000 to 18,000 bottles per hour are attainable. Since Glaskin is applied inside the bottle, the risk of damage to the barrier during transport and storage is eliminated.
Glaskin uses the vacuum deposition process to coat bottles with SiOx. However, its uniqueness lies in newly developed techniques, which provide previously unattainable barrier performance levels. Tetra Pak can deliver both barrier bottles and closures direct to customers' filling lines and can support its Glaskin customers with on-site bottle supply.
Environmental studies of Glaskin have led to the conclusion that the extremely thin layer of inert SiOx deposited inside each bottle will allow bottles to be recovered through the existing PET recycling channels.
Over-Injected Barrier Layer
The other new product, Sealica, is also a proprietary technology, using a patented injection overlay process to injection-mold a high-barrier polymer layer onto PET preforms. The proprietary barrier material is a thermoplastic epoxy resin, supplied through a strategic alliance between Tetra Pak and The Dow Chemical Co. Dow will sell the barrier material under the trademark BLOX Resins.
The single over-injected barrier layer on PET preforms can be varied in thickness to give the final bottle more or less barrier potential, based on individual customer needs. Sealica technology uses specialized equipment and processes to first injection-mold a PET preform and then, on the same platen, over-inject a single layer of the proprietary barrier material, BLOX.
The addition of the Sealica barrier material at the preform stage gives users the flexibility to purchase small quantities of preforms without long-term commitments and also use high-barrier preforms in existing stretch blow-molding machines. The thickness of barrier material can also be changed to optimize package performance/cost balance.
Tetra Pak says existing recycling streams can also accommodate Sealica. The BLOX layer, once removed, can be reused in a variety of applications, including loosefill packaging, hot-melt adhesives, tie layers, adhesion promoters and polymer additives.
Shelf-Life Tests Successful
Glaskin and Sealica technologies are designed to provide customers in the beer, juice and CSD markets a complete range of gas-barrier solutions tailored to their specific needs for barrier performance, bottle versus preform supply, package volume demand and capital investment.
The two technologies have been in extended shelf-life tests for more than a year with brewers and beverage companies in Europe and the United States. In all tests, reports Tetra Pak, Glaskin and Sealica have met or exceeded customer performance requirements.
Both technologies are expected to be fully compatible with existing recycling systems. Internal evaluations and laboratory assessments are complete, according to Tetra Pak, and final industrial scale recycling tests should be complete in the first trimester 2000.
Commercial releases of Glaskin and Sealica will begin in the first quarter of 2000 and ramp-up through the year.
Edited by Bill Noone