Belgium’s Milliken Chemical has installed a Series 2, SBO4 machine from Sidel in its R&D center. This is to support research into injection stretch blow moulding clarified polypropylene. The project, which was started in May 2005, was a joint research venture between Sidel and Milliken to increase production speeds for polypropylene (PP) containers and its acceptance in the market as a cost-effective solution. It was also a cooperative effort to develop a methodology in making PP more competitive with PET, in terms of cost, for a variety of bottling applications including hot fill applications.
Technical advancements in resin formulation and pre-forms design now allows the beverage industry to use clarified PP. This methodology allows bottlers to inject material in pre-forms that get stretched and blown into low-cost, perfectly transparent bottles that can also be hot fill packaged.
This is a new development for Milliken, as the use of the new resin is a significant bottling breakthrough for PP. Traditionally, PP was considered to have poor barrier properties and as a result PP containers were not suitable for the carbonated beverage or oxygen-sensitive food markets.
According to Milliken, PP and its hot fill packaging abilities, makes it possible to market the product to the food, beverage and dairy industries. PP is a cost-effective alternative even for cold fill packaging because of its exceptional moisture and aroma barrier properties. PP can be used for packaging spices, powdered food, instant coffee, cereals or capsules, significantly improving its marketability.
Contractors and capacity
The new methodology uses a random copolymer PP from the Braskem company of Brazil. The PP is clarified with Milliken’s Millad 3988 and moulded on Sidel’s SBO 8 machine. Braskem, Milliken and Sidel formed a partnership to develop clarified PP bottles that facilitates hot fill packaging for both foods and beverages. The production speeds of Series 2, SBO4 machine went up to 1,600bph during trials conducted at Milliken Chemical’s research facility.
The SBO Series 2+ blowers are 12 standard machines with 4 to 28 cavities and production rates ranging from 6,400bph to 45,000bph and package from 0.25L up to 3L in standard sizes. The machines can also be designed to accommodate containers up to 5L or 6L.
The increase in productivity and reduced air consumption ultimately result in lower unit cost of packages. A new housing design facilitates maintenance and format changeovers, and increases actual production time. All of these enhancements help cut bottle production costs by nearly 10% while guaranteeing equipment performance and package quality, and with fewer dead spaces in the blowing air distribution system, savings of up to 15% can be made in the consumption of 40bar air.
In being able to meet its customers’ requirements, Milliken promotes PP as a viable, cost-efficient alternative for beverage producers.
The beverage industries can now reduce the use of preservatives in their formulas because they can adopt the hot fill packaging process for their products. This move can be promoted as a healthy option.
PP is now in competition with PET, given the on-going research in the former and the rising costs of the latter. In effect, PP can corner a market share in selected industries, especially retortable containers.
PP has lower density when compared to PET and the bottles are about 40% less costly by volume. PP bottles also weigh less than PET, while their “practical clarity” is equal to PET bottles.
PP will now be available to a wider consumer base. OPP is limited to niche uses like pediatric nutritional supplements and pill bottles, mainly in Asia and South America. The new PP presents an opportunity to transform the cost of packaging water, juice, hot-filled foods, dry powders, and personal-care products. PP’s advanced equipment, optimized pre-form and bottle designs, and improved resins and additives tailored for bottles will overcome the disadvantages of OPP.