Page 28 - Plastics News April 2017
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          set at levels that also remove as much as 20% of the PET   if present when the
          (particularly the newer light-weight water bottles); in the   PET  re cycla t e  is
          case of float / sinking, the label material simply sinks with   processed. While some
          the PET, potentially causing the contamination impacts.  applications (fiber)
                                                                can tolerate certain
          Melt and Bleed:
                                                                contaminants better
          The full-wrap label material tends to melt or get sticky   than other applications
          at  temperatures  of  165  degrees  centigrade  or  lower.   (packaging), the overall quality of the RPET is impacted
          This results in material coating or clumping in dryers   as is next-use customers’ ability to process it back into
          and requires costly and unscheduled maintenance. Many   products of acceptable quality.  These impacts include,
          labels tested also bleed ink into the wash water while   but are not limited to:
          being processed. While the impact of this on flake quality
          is still being evaluated, there are also concerns about the   -  Substantial loss of intrinsic viscosity (IV)
          impact of effluent discharge.                         -  Color issues, including yellowing and/or graying
                                                                -  Loss of clarity/haze
          Intermediate Processing:
                                                                -  Extruder drool or drip
          An increasing number of Material Recovery Facilities (MRFs)
          are investing in equipment that uses near infrared (NIR)   -  Black specks
          technology to positively identify PET containers, then uses   The Solution:
          compressed air to sort them from the other recyclables.   While “temporary” solutions have been discussed involving
          Full-wrap labels tend to blind these detection systems,   zippered or scored labels that would make them easier
                                         preventing them from   to remove, or a return to paper labels, clearly the most
                                         identifying the PET,   effective long--term solution is to use a label that floats
                                         resulting in either the   and is compatible with the existing label stream and PET
                                         loss of the container   recycling infrastructure.  For those companies embracing
                                         to the waste stream,   the  principles  of  sustainability,  addressing  this  issue
                                         o r  necessitating     is a priority since there is no sustainability for plastic
                                         additional manual      bottes without recycling, and no recycling without an
                                         sortation. This added   economically viable reclamation industry.  Full--wrap
                                         cost  lengthens the    labels that sink inwater are threatening this viability
                                         payback of these       and  the  overarching  sustainability  premise  for  PET—by
          investments, many of which are retrofits.             adversely impacting the recycling of not just the PET

          Contamination Impacts:                                bottle,but the label itself.  Continued use of full---wrap
                                                                labels that sink threaten these fledgling efforts, and once
          Depending on the label material substrate, these residual   again runs counter to sustainability principles.
          contaminants  cause  a  myriad  of  further  challenges

                                        Why can’t reclaimers remove these labels...
     In a nutshell: they do not float in water, but the problems really start earlier in the process.
     Most reclaimers, particularly those that process curbside material, perform a pre-wash on the bottles.
     This is done to remove as many labels as possible prior to the bottles being presented to the autosort unit for identification. These pre-washers run at very hot
     water temperatures, or even steam conditions, to loosen the dirt and labels by shrinking the bottle a little. Unfor tunately, the materials generally used in the
     full-wrap labels – OPS, PETG, PLA and PVC – shrink even more, tightening around the bottle. They become impervious  to standard agitation, or even attempts
     to slice them off manually. On some occasions, labels actually melt over the bottles. If the bottles are not removed after the prewash, the labels will travel
     through the granulat ion and  elutriation, float/sink, wash and dry parts of the process (not necessarily in that order) and stay with the PET, resisting efforts to
     be separated, either by air or water, due to their specific gravity being too similar to that of PET (greater than one). In some systems, the contaminating labels
     will curl or otherwise densify making it even more difficult to remove them. In most cases, the dried RPET flake is then passed through different types of flake
     sorters that  remove trace contaminants, including color, metal and other resin as a final quality control step. While many flake sorters can detect most of the
     offending label materials, none are wholly effective at removing the quantity of material seen at this stage if these bottles are left in the stream at the current
     or increased percentages. The flake sorting technologies are meant as a final polishing step, not for primary sorting

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