The guidance considers the direct application of inks to the film package as more impactful than inks printed on a label substrate, as direct printing fulfills a decorative function whereas a label conveys more limited information.
Unprinted and non-laminated PE
Unprinted and non-laminated material has the highest value as a recycled stream since it has the widest variety of end-use applications. It is the most cost effective to process through the recycling system.
Tested inks, primers, coatings and laminating adhesives that disperse in the final polymer without having an impact on quality
APR offers various testing protocols and options for recognition to companies striving to design and commercialize Preferred printing systems, inks, coatings and laminating adhesives for PE films. Test results demonstrating recycling compatibility can determine material classification. One company has received Critical Guidance Recognition for a two-part, water-based, acrylic/urethane hybrid lamination
adhesive along with a two-part, water-based, acrylic/urethane hybrid surface coating system. One company has received Critical Guidance Recognition for a two-part, solventless polyurethane lamination adhesive used at nominal 2% loading on undecorated polyethylene films.
Direct printing, primers & overprint lacquers and coatings, glossy or matte
Certain levels of ink components dispersed in the final polymer are thought to be responsible for the grey-green color of recycled PE pellets. As long as there is no impact on physical or chemical properties of the PCR, and the correct inks are used, markets exist for such colored PCR pellet.
The amount of printing should be limited since heavy levels of certain ink components may degrade and volatize in the extruder, causing gels and specks in the final product even with vented extruders. Large amounts of printing can overwhelm the capacity of these extruders to remove the volatile components.
Some direct print inks bleed color in the reclamation process, discoloring the PE in contact with them and possibly diminishing its value for recycling. Since most recycled PE is colored, the impact of bleeding inks may not be significant; however, since the end use is not known beforehand, inks should be chosen that do not bleed color when recycled.
Heavily printed film of dark colors can be problematic since the dark color affects a large amount of polymer, limiting its potential for reuse. (see discussion in PE Film Color section)
Testing of inks, primers, coatings and laminating adhesives is encouraged to identify innovative technologies that can be preferred for recycling.
Laminating adhesives, cold seal adhesives
The amount of adhesive should be limited since heavy levels can degrade and volatize in the extruder and may cause gels and specks in the final product even if most recyclers use vented extruders. Large amounts of adhesives can overwhelm the capacity of these extruders to remove the volatile components. Heavy adhesive levels also potentially impact the physical properties of the end market PCR or product.
See "Requires Test Results section"
High levels of inks, primers, coatings and laminating adhesives that cause significant degradation of physical and mechanical properties of the end market PCR or product.
See “Requires Test Results” Section
REQUIRES TEST RESULTS
Even though they are currently recycled commercially, there is currently no solid evidence available for a complete understanding of the impact of the packaging components above on the recycling process and the recycled material. Test results or equivalent evidence need to be developed, based on which these guidelines will need to be confirmed or updated.
Curable inks, coatings and adhesives
Chemically, EBeam or UV curable inks, primers and adhesives are thermoset in nature, not melting with the thermoplastic components of a flexible film, thus acting as a contaminant in the recycling process. Depending on the amount used, they may limit the potential reuse of recycled films by negatively impacting film appearance (gels, specks) and mechanical properties.
Inks designed for metallic appearance are not always removed in the recycling process and are melted and blended with the PE. This may cause material discoloring. In many cases a metallic ink will be detected early in the recycling process by metal detectors designed to protect machinery from catastrophic damage. Metal detectors are unable to differentiate between a metallic print and a solid metal part, so the entire package is normally discarded rather than accept the risk.