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PTi study reaffirms FDA Guidelines for use of virgin PET cap layers as an effective functional barrier

Mon, Mar 13th 2017 04:45 pm

AURORA, Ill., February 20, 2017 - Processing Technologies International (PTi), a leading global manufacturer of high-performance sheet extrusion machinery,has released the findings of an independent study which reaffirms FDA guidelines for the use of virgin PET cap layers as functional barriers over Post-Consumer Recycled Non-Letter of No Objection (hereinafter referred to as PCR) PET flake materials for direct food packaging use at room temperature.  The study, which was completed in conjunction with Plastic Technologies Inc., Holland, Ohio, and Container Science Inc., Atlanta, Georgia, found that a 1-mil-thick virgin PET cap layer meets the necessary functional barrier requirements, eliminating surface contaminates within multilayer food packages made of PCR PET materials for room temperature (70°F/21°C) applications.  PTi presented these findings in December at the Extrusion 2016 conference, sponsored by Plastics Technology magazine. 

This study was prompted by a recent 2016 European industry report by Dr. Frank Welle of the Fraunhofer Institute, "Assessment of Recyclates behind Functional Barriers", that questioned the efficacy of an ABA structure with PET recyclates behind a functional barrier and suggested that the virgin cap layer may become contaminated during extrusion, rendering the functional barrier inadequate.   The European report findings were based on testing of recycled PET packaging at elevated use temperatures as high as 212°F/100°C (Welle, 2016), which is not in keeping with guidance stipulated by the FDA recommendation (i.e.; room temperature and below) using a minimum of 1 mil thick virgin PET cap layer to encapsulate the PCR PET materials for direct food contact packaging applications (FDA, 2006).

"Our study set out to examine the elevated application temperature relevance used as part of the Fraunhofer Assessment and reaffirm virgin PET for suitability as a functional barrier and its corresponding FDA guidelines.  Our simulation results demonstrate that a 1-mil virgin cap layer is adequate protection for a PET food package when used at room-temperatures," said Sushant Jain, Senior Scientist - Applications and Technology, for PTi.  In co-extruded multilayer PET structures, the FDA recommends a 1-mil-thick virgin cap layer for room temperature applications and 2 mil for higher temperature use (up to 150°C) to prevent permeation of contaminants migrating from the PCR PET regrind core layer of the packaging material into the contained food (FDA, 2006).  The virgin cap layer provides protection from unhealthy contact or transfer of inks, adhesives, chemicals, or other materials not meant for consumption.

PTi performed several simulations as part of this study.  Table 1, Functional Barrier Layer Simulation Results For 40 Mil Sheet, summarizes data from four (4) different simulations that modeled the production of a 40-mil-thick PET sheet with a 10/80/10% virgin/regrind/virgin layer structure at a combined rate of 2000 pph.  The first simulation assumed a conventional single screw extruder (i.e.; no devolatilization capability) processing the 80% core layer using only PCR PET flake.  The second simulation changed the formulation to a 50% PIR and 30% PCR PET flake blend.  The third simulation repeated the formulation used during the first simulation while adding the devolatilization benefits of the high vacuum twin screw extruder using a Bandera co-rotating twin screw (HVTSE®).  And finally, the forth simulation repeated the formulation of the second simulation while also adding the benefits of the HVTSE® process.

For each of these four (4) simulations the results demonstrate the virgin cap layers maintained its suitability as a functional barrier since the resultant uncontaminated virgin cap layer thicknesses exceed the 1 mil FDA recommendation (FDA, 2006).   The third and fourth simulations further demonstrate the devolatilization benefits using the HVTSE® dryer-less process which is shown to increase the resultant uncontaminated virgin cap layer thicknesses (i.e.; the resultant functional barrier layer thickness) due to a significant reduction of contaminant concentration levels in the core layer.

In summary, this study was effective in demonstrating the importance of various factors with regard to contaminant migration with the most significant being the correlation of higher migration rates at increased application temperatures.   In the Fraunhofer Assessment, the relative permeation rate at 212°F(100°C) used as a point of origin (Welle, 2016), is several orders of magnitude higher than the rate at room temperature, according to Jain. 

Other conclusions from this study indicate that exposure time during extrusion processing has some impact with the simulation models showing primary contaminant migration occurring in the feed block and die area.  However, at this point migration is found primarily at the interface and not through the virgin cap layer, according to Jain.  Furthermore, this study demonstrates that virgin cap layers can remain uncontaminated at a layer thickness greater than 1 mil, proving the functional barrier remains intact during the extrusion process and reaffirming FDA guidelines for use as an effective barrier.  "Our study eliminates any doubt regarding virgin PET's effectiveness as a functional barrier," Jain concludes.

Table 1.


  1. FDA.  (August 2006).  Guidance for Industry: Use of Recycled Plastics in Food Packaging: Chemistry Considerations. http://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/IngredientsAdditivesGRASPackaging/ucm120762.htm#theuse
  2. Welle, Frank, Dr.  (March 3, 2016).  Assessment of Recyclates behind Functional Barriers.  PET Recycling for Food Contact Conference.  Fraunhofer Institute for Process Engineering and Packaging (IVV).  https://www.researchgate.net/publication/301864759_Assessment_of_Recyclates_behind_Functional_Barriers. 


About Plastic Technologies, Inc.
Plastic Technologies, Inc. (PTI) is recognized worldwide as the preferred source for preform and package design, package development, rapid prototyping, pre-production prototyping, and material evaluation engineering for the plastic packaging industry. For more information, visit www.plastictechnologies.com

About Container Science Inc.               
Container Science, Inc. was founded in January 2002 to offer materials science expertise for improving the basic performance, quality and economics of PET and other plastic container materials. The corporation provides a fundamental knowledge of the chemistry and science associated with plastic containers, and we translate that understanding into practical solutions that address the needs, issues and opportunities for this industry.

The company's clients are suppliers and customers throughout the value chain of the PET plastic packaging industry across the world. These clients include resin producers, package designers, package developers and converters, as well as bottlers and other end-users.

Founder and President, Dr. Mark Rule, earned his Ph.D. in physical-organic chemistry from Yale University. He spent 16 years with Eastman Chemical Co. and six years with The Coca-Cola Co. before founding Container Science, Inc. His knowledge of materials science and the plastic container value chain has been acquired through leadership roles in basic and applied research, new product development and commercialization, negotiations, strategic alliances and licensing, strategy development, and new business development. Dr. Rule is the author/co-author of over 85 U.S. patents ranging from technologies for raw material synthesis to methods to improve package shelf life. His expertise covers not only the fundamental science of plastics, but also the economic and market forces at work in the industry. For more information, visit www.containerscience.com.

About Processing Technologies International LLC (PTi)
Processing Technologies International LLC, based in Aurora, Ill., is a leading global manufacturer of high-performance sheet extrusion machinery, serving more than 20 countries. Established in 1988, PTi produces and services single-screw extrusion equipment for many end-use markets including packaging, construction, automotive, lawn and garden, office products, signage and displays, and appliances. PTi's extrusion systems are engineered to exacting standards and offer an exceptional range of design features which result in superior equipment performance. More information is available by calling (630) 585-5800 or visit www.ptiextruders.com.