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FLEXO Magazine : March 2008
TECHNOLOGIES & TECHNIQUES www.flexography.org MARCH 2008 FLEXO 39 RECYCLABILITY All known types of PLA are recyclable. There is no reason why you cannot recycle these films. Mechanically, it is possible. The issue is getting to critical mass. You have to have enough of an availability of a particular material to recycle it. Of course, there are those critics who say PLA can't co-mingle, but most plastics can't co-mingle. For example you can't mix PET and PETG; the melt points are different. PLA can be put through the current recycling process without an issue. The problem is how do you separate it out? There is equipment today that can separate material based on polymer makeup. Unfortunately, not many facilities are using the technology; new re- cycling equipment likely will incorporate this. Ultimately, the true question is whether the community will put enough of the material into the recycling stream. The vast majority of PET that is recycled is water bottles. We recycle about 23 percent of those. That leaves about 4 billion pounds of PET water bottles that are going into landfills. PET water bottles generally incor- porate labels made from paper or BOPP lamina- tions, not PETG shrink sleeves, etc. BOPP and paper can easily be sepa- rated from PET bottles. Shrink sleeves generally are not recycled because of contaminants like ink. Additionally, the fact that density values do not allow proper separation of bottle and label cause the recycler to physically remove these at the MRF (Materials Recycling Facility) to avoid co-mingling of different substrates. In truth, very little flexible packaging is recycled regardless of type. In the U.S., we recycle only about 6 percent of the plastic we produce. When it comes down to it, there are alternative ways to get biopolymers out of the waste stream. PLA can be incinerated. It does not give off negative emissions and produces good BTU energy values. When placed in a landfill, it is the same as entomb- ing just about any other plastic. Uniquely, PLA can be composted, which would fulfill a true cradle-to-cradle cycle. USABILITY Overwraps, pouches, bags/sacks, shrink labels, etc.---biopoly- mers can be used in a lot of different flexible packaging applica- tions. Right now, the perception is that PLA is not viable because of temperature resistance, lack of availability, mechanical proper- ties, etc. But here are the facts: There is plenty of resin available. Some have said that the availability of corn could be an issue; however, less than 0.5 percent of the existing corn crop is needed to create the supply necessary to meet the resin manufacturing demand. Then there is the belief that the supply of corn will be jeopardized by the demand for ethanol. Even if a shortage of corn was the case, there are other economical sources of starch, such as sugarcane, beats, switch grass, etc.---all of which can be used to make this product. In addition, currently there is technology in development to improve crop yields to further enhance corn availability. Heat resistance is another myth. Now, normally PLA has a 104-degree F threshold. This is where EarthFirst stands out. It has a resistance in the 140 degree F range. Generally speaking, it is handled very similarly to petrochemical-based products. In fact, in the industrial manufactur- ing process, it requires less heat to make heat seals and less heat to shrink full-body shrink sleeves. Therefore, it actually conserves some energy in the convert- ing process. Compared to polypropylene, when making heat seals on bags, it takes less en- ergytogetittoade- sired temperature based on its specific heat property. Last but not least, the printability of EarthFirst PLA is also exceptionally good. It has a high natu- ral dyne level of 38 and, in general, there has been a lot of success with converters print- ing this with almost any process. It can also heat seal using every method---hot wire, hot knife, crimp, impulse, etc. This product is gaining acceptance because of its mechanical properties and of- fers the benefit of environmentally friendly properties as an added bonus. Bioploymers are a trend gaining credibility in the market be- cause of large brand owner awareness and acceptance. Other bio- polymer resins are on the horizon that will complement current offerings and address applications that cannot utilize products available today. ABOUT THE AUTHOR: Rich Eichfeld is vice president of business development for Plastic Suppliers Inc. A graduate of Rutgers University, Eichfeld has spent his 18-year career selling petrochemical-based films ranging from polypropylene to polyester. This background, in addition to his current focus on the burgeoning biopolymer industry, make Plastic Suppliers particularly well suited to addressing the current questions facing today's environmental industrial film applications . For more information about PLA or EarthFirst, contact Plastic Suppliers at 614-471-9100, www.plasticsuppliers.com; or NatureWorks LLC at 877-423-7659, www.natureworksllc.com. Comparison of Biopolymers to Petrol Polymers Fossil Fuel Usage PLA PVC PET HDPE PHA PP PS Cello Nylon 49 48 51 49 39 29 93 90 39 32 81 31 37 32 27 Energy to Make Raw Materials from Oil Cradle to Factory Gate (In Mega Joules per Kilogram) 1KgofOil=45.8MJ