The Association of Plastic Recyclers
  • HDPE

    HDPE

LABELS, INKS AND ADHESIVES

Before HDPE bottles are granulated, complete packages with labels and closures are likely to be sorted by a NIR optical sorter and run through a sensitive metal detector. These situations create the need for testing to evaluate the impact of a label on NIR optical sortation or metals detection:

  1. If a label does not allow the package to be positively identified as HDPE by NIR sorters, the container will go to the waste stream and not be recycled.
  2. If metal decoration used on a label is detected by a metal detector, the package will be ejected and sent to waste. Metal decoration can include: vapor deposited films, metal foils, and metallic flake inks.

During the reclaiming process, mixed color HDPE packages are most likely washed in water near room temperature and with mild detergents. These wash conditions will have negligible impact on inks and adhesives and in most cases labels, inks and adhesives are expected to become included in the recycled HDPE product.

PREFERRED

Automated sorting performance criteria:

  • For containers with a brimful volume of 550 ml or less, the surface area coverage of the label is no more than 55%, and no metal decoration is employed on the label.
  • Surface area is defined as the area of the label divided by the area of the side wall and shoulder of the container. The area of the neck ring, threaded finish and base are not included in the area calculation. Metal decoration includes vapor deposited metal films, metal foils, or inks with metallic pigments.

    Containers with no more than 55% surface area coverage by a label are expected to sort accurately in both NIR and color optical sorters. For labels with metal decoration see section on Labels with metalized materials

  • For containers with a brimful volume of over 550 ml, the surface area coverage is no more than 75%, and no metal decoration is employed on the label.
  • Surface area is defined as the area of the label divided by the area of the side wall and shoulder of the container. The area of the neck ring, threaded finish and base are not included in the area calculation. Metal decoration includes vapor deposited metal films, metal foils, or inks with metallic pigments.

    Containers with no more than 75% surface area coverage by a label are expected to sort accurately in both NIR and color optical sorters. For labels with metal decoration see section on Labels with metalized materials.

  • Labels containing metalized material that meet APR Preferred Design per APR-RES-SORT-04
  • Metalized material content on labels below the preferred surface area perAPR-RES-SORT-04 are considered preferred.

    Metalized material includes vapor deposited metal films, metal foils, or inks with metallic pigments.

Polyolefin Film Labels

Polyolefin labels are commonly expected to be PP films or PE films. This includes film labels for each of conforming, adhered, and in-mold style of labels. Some additional considerations:

  • If the label is designed to remain with the granulate (an adhered or in-mold label) and adhere to the granulate, or is molded in, the label should not interfere with the ability of the granulate to float in water.
  • If the label is designed to separate from the HDPE container, it is desirable that the label floats so that the label might be recovered for recycle value.
  • Those committed to developing a circular economy for HDPE containers will favor labels with either of these characteristics:
    • Labels have been shown to be compatible with HDPE recycling using the APR Critical Guidance Test for HDPE containers.
    • Labels are made from fractional melt index HDPE and so are fully compatible with the HDPE used to make the bottle.

Film labels with density > 1.0 g/cm3designed to release from HDPE container in wash and sink in water per APR-O-S-01-PO

When used with an adhesive that releases in the wash, film labels with density greater than 1.0 g/cm3detaches from the HDPE before the float-sink tank where it sinks and is removed. Even though the float-sink process is imperfect, the small amounts of this type of film label entering the extrusion process are not catastrophic.

Click below for commercially available Labels, Inks and Adhesives that have achieved APR Design for Recyclability Recognition

APR Design® for Recyclability Recognitions

DETRIMENTAL

Film labels with density > 1.0 g/cm3designed to stay adhered HDPE container in wash

When used with an adhesive that does not release in the wash, Film labels with density greater than 1.0 g/cm3 enters the extruder with the HDPE where they are incompatible.

PVC film labels

PVC, when used with an adhesive that does not release in the wash, enters the extruder with the HDPE where they are incompatible. PVC degrades at HDPE extrusion temperatures and renders large amounts of the recycled HDPE unusable. When used with an adhesive that releases in the wash, these labels sink in the float-sink tank where they are removed. But because the float-sink tank is imperfect, and even a very small amount of PVC entering the extruder causes severe quality and yield problems, this material is detrimental.

Paper labels

The HDPE reclamation process involves water and agitation. The paper that detaches from the container when subjected to these conditions becomes pulp, which does not sink intact but remains suspended in the liquid, adding load to the filtering and water treatment systems. Paper remaining adhered to the HDPE travels with the HDPE to the extruder where the material carbonizes and causes color defects. Even after melt filtering, the burned smell and discoloration remain with the recycled HDPE thereby negatively affecting its potential reuse. Non-pulping paper labels used with non-releasing adhesives compound the problem since the entire label enters the extruder. Non-pulping labels, heavy enough to sink and durable enough to withstand the washing process that are used with releasing adhesives may alleviate this issue.

RENDERS NON-RECYCLABLE

None Specified

REQUIRES TEST RESULTS

Labels that exceed the surface area coverage as described in Preferred Guidance section

Labels with high surface area coverage may interfere with detection of the HDPE container. The label substrate (film or paper), inks, and metal decoration can interfere with NIR detection when the label covers a high surface area of the container. Also, high label surface area coverage may cause an HDPE container to be sorted for a different resin if resin of label is not PE.

If one’s design is outside of the best practice guidance above, the labeled bottle must be evaluated using the APR test methods below.

DEFINITIVE TEST - NIR

Labels containing metalized materials that are above the maximum surface area coverage per Screening Test below.

Labels that have surface areas above the Preferred Surface Area specified in the Screening Test below would need to be tested using the Benchmark Test below to verify they are under the spherical equivalent thresholds.

Without further testing, metal foils with surface areas above the Preferred Surface Area in the table are categorized as detrimental due to a higher probability of being removed by the metal detector during sortation.

Solid foils will continue to render the package non-recyclable per APR’s definition.

SCREENING TEST

BENCHMARK TEST

Label inks

Some label inks bleed color in the reclamation process, discoloring the HDPE in contact with them and possibly diminishing its value for recycling. Since most recycled HDPE is colored, the impact of bleeding inks may not be significant; however, since the end use is not known beforehand, label inks should be chosen that do not bleed color when recycled. If inks redeposit on natural HDPE flake, this discoloring may diminish its value for recycling. Inks should remain adhered to the label and not bleed into wash water to avoid this potential discoloration. The APR test protocol should be consulted to determine if an ink bleeds.

SCREENING TEST


DEFINITIVE TEST

Direct printing on HDPE containers

Inks used in direct printing may bleed or otherwise discolor the HDPE during the recycling process or introduce incompatible contaminants that reduce the value of the recycled HDPE. The specific ink must be tested to determine its effect. Companies that are considering direct printing technologies and are unsure of their compatibility with recycling should ask their suppliers to provide APR test results.

DEFINITIVE TEST

Label/Adhesive combinations where adhesive release and substrate float/sink behavior are not known.

Testing must show that adhesives will either wash off cleanly from the HDPE in the recycling process or be compatible with HDPE. Since typical HDPE recycling process conditions are not aggressive enough to remove all adhesive material, a certain amount of residual adhesive is to be expected in recycled HDPE. Such adhesive residue that is not removed from HDPE during the wash step is a source of contamination and discoloration when HDPE is recycled. For these reasons, minimal adhesive usage is encouraged.

DEFINITIVE TEST

The APR is developing a screening PP/HDPE Adhesive Test to classify adhesive as either wash friendly, non-wash friendly and compatible with HDPE, or non-wash friendly and incompatible with HDPE. Non-wash friendly, incompatible adhesive is detrimental to recycling.

Get In Touch

Linkedin

Linkedin

Twitter

Twitter

Facebook

Facebook

Soundcloud

Soundcloud

Vimeo

Vimeo

Youtube

Youtube

APR

2050 M Street NW

Washington, DC 20036

Subscribe

Invalid Input