ORLANDO (ICIS)--Technology developments for polyolefins like polypropylene (PP) are advancing in strength, sustainability and physical appearance, giving PP properties that were formerly out of reach, Milliken said on Thursday.
“That’s something we’ve been working on for about five years now, trying to get polypropylene as clear as other plastics,” business development manager Emily Blair said on the sidelines of this year's National Plastics Exposition (NPE).
“The way we look at polyolefins, polypropylene and polyethylene for that matter; it’s the most sustainable plastic in the industry with the lightest density,” she said.
Milliken's Millad NX 8000 clarifier additive enhances aesthetics, clarity and quality for PP, Blair said.
Though it has attributes such as density, heat resistance and recyclability, PP’s typical hazy, cloudy appearance has discouraged markets like food packaging from using it, she said.
Higher meltflows, the ease of how fast a thermoplastic polymer moves during production, has also been a growing trend for the last several years, she added.
Improving the recycling and strength of PP without losing product stiffness is important, Blair noted, as faster meltflows can lead to poor impact properties.
“What’s preventing more people from using polypropylene in more recycled material specifically, is the physical properties aren’t there,” she said.
The end product cracks, she explained, or the meltflows are too low, not flowing fast enough through the process to make the part quickly.
“What you see people do with recycled materials, or virgin materials for that matter, is when they try to get in this space, they use impact modifiers,” she said. “When they do, they lose stiffness. The product becomes too soft.”
Trying to hit needs at both sides of the supply chain is another challenge, with brand owners looking to use more recycled plastic in durable goods, or consumer goods.
“The converter has to be able to process it, or at least make sure it meets the same physical requirements,” Blair said. “The reason why a converter is telling them ‘I can’t do it’ is because the material doesn’t flow, or it cracks. Typically if you drop a part, it cracks in an empty void of no rubber domains.”
To address that, Blair said that Milliken has been developing a chemical process that redistributes the rubber domains.
If you can take the rubber domains, and redistribute them in a way that makes them smaller, you get better flow and impact properties, she said.
Cost savings and sustainability still go in conjunction, Blair added.
“The sustainability is an underlying benefit of what we do,” she said. “The challenge customers run into is how to make products more sustainable, without costing more money. People put goals out there, but it’s not always realistic with the products available.”