A global team headed by Milliken & Company completed a breakthrough research and development program that has dramatically increased beverage container production rates using polypropylene (PP), opening the door for the use of less expensive plastics in applications currently in PET, HDPE and cartons.  

The 18-month effort, which focused on preform and bottle designs, process expertise and resin formulations for two-stage Injection Stretch Blow Molding (ISBM), resulted in productivity increases of more than 30 percent for PP. These results mean that production levels have been achieved for PP that match those for PET, making PP an attractive, cost-effective option for many beverage applications.

The beverage industry had been interested for some time in the use of PP for certain beverage applications because of its cost advantage over PET, which can be as much as 20 percent. The challenge up until now, however, was that the process of beverage container creation was much slower with PP, which virtually eliminated the cost advantage in terms of lower raw material costs. Milliken’s research and development program effectively addressed this issue.

By assembling a global team that included its own research and development personnel, Milliken Chemical, along with a leading machine manufacturer, explored how the productivity issue could be overcome. The team was challenged with achieving increased productivity while using existing ISBM equipment to produce high quality PP containers suitable for beverages.

In addition to lower costs, PP is superior to PET because of its excellent mold duplication properties (for engraved logos and designs) and the fact that it can be hot filled at temperatures up to 209 ° F (98°C). This feature can be a tremendous advantage for beverages such as juice drinks, isotonic beverages and other applications where hot filled PP serves as an enabling technology.

Because of this development project, brand managers for these products now have a new high quality container option that will also open up significant cost advantages.

Milliken’s Millad 3988, which is traditionally used to enhance clarity in PP, also contributed to cycle time efficiency when injection molding preforms. Other benefits from the use of Millad include clarity of the oriented and non-oriented components (neck and base), higher rigidity and HDT of the bottles, industrial level processing control and stability in stretching and blowing of the preforms into containers.