Clear PP Featuring Milliken’s Millad Technology Offers Attractive Option to PET for Glass Replacement in Packaging Applications

Polypropylene clarified with Millad 3988i can be processed using one- or two-stage injection stretch blow molding and extrusion blow molding to make bottles.

09/11/07 Clear polypropylene (PP) clarified with Millad 3988i from Milliken & Company is a better choice than polyethylene terepthalate (PET) for glass replacement in packaging applications, as Unilever South Africa Foods discovered. Not only does clear polypropylene have the potential to be a less-expensive solution than PET, due to a combination of raw material cost and lower density, but it may also deliver excellent clarity plus the added benefits of improved moisture barrier performance and higher hot-fill temperatures. Seeking to launch a new range of seasonings, with durable lightweight plastic in new bottles for its Robertsons’ line of specialty seasonings, Unilever South Africa Foods selected clear PP featuring Millad 3988i clarifying agent. The material is manufactured during one-stage injection stretch blow molding (ISBM) to create attractive containers.

“Clear PP was an inspired choice for our beautiful new seasoning bottles, offering greater design freedom than glass and delivering excellent clarity for an unimpeded view of the contents,” said Bruce Volmink, packaging development manager, Unilever. “Also, the superior moisture barrier properties help ensure long shelf life for delicate spices and herbs. Our team depended upon Milliken specialists for their extensive technical and processing expertise in the development of this new packaging together with our supplier."

Milliken offers customers a wide range of application development assistance, including test and production machinery for process optimization and on-site packaging designers, at its Technical Service and Development Lab in Spartanburg, SC.

Advantages of Clear PP for Packaging

Before the advent of Milliken’s advanced clarifying agents, PP was frequently not a practical packaging material due to its haziness. Millad 3988i clarifier, a third-generation sorbitol acetal technology, produces excellent clarity suitable for most see-through packaging applications. In addition, compared to PET, PP offers the following benefits:

• Lower density – With a specific gravity of 0.9 g/cm3, PP is less dense than PET (1.27g/cm3). By requiring less PP per unit, manufacturers can save on material costs.

• Higher temperature resistance -- PP is much more heat-resistant than PET, making hot filling easier. Above 80 C, PET typically loses its integrity, while PP can withstand temperatures of up to 130 C.

• 2x-3x better moisture barrier performance – PP has a distinct advantage over PET in vapor barrier performance. Improved protection against moisture permeation helps protect contents and extend shelf life.

Polypropylene clarified with Millad 3988i can be processed using one- or two-stage injection stretch blow molding and extrusion blow molding to make bottles. The material is also suitable for injection molding, sheet extrusion and thermoforming.