HDPE (High Density Polyethylene, Resin Identification Code #2)
Due to its toughness, natural UV barrier properties and chemical resistance HDPE is one of the most widely used packaging resins. It is easily injection molded, blow molded, or otherwise processed into a bottle, canister, pail, tub, squeeze tube or closure. In its natural state, HDPE appears a milky white color. This is due to light reflection on the polymer structure rather than a colorant.
HDPE properties are commonly enhanced with colorants, additives and fillers, or it is placed alongside other polymers in a multi-layer package. Each modification and addition to the natural HDPE in a package must be considered for its effect on the recycling stream. Non-HDPE packaging features should either be economically removed from the HDPE in the typical recycling process or be compatible with HDPE in future uses. Of particular concern are mineral fillers or additives that cause the overall blend to sink in water. The density of HDPE is 0.94 - 0.97 g/cm3 so it floats in water. Density is an important property as reclaimers typically rely on float - sink tanks to separate polymers and to remove contaminants. Melt flow is also an important consideration given end uses of PCR. Specific guidance can be found in the HDPE Critical Guidance or other design resource documents.
Per the scope outlined in the Design Guide introduction , the following guidance is focused on postconsumer packaging items that are typically picked up in single stream curb side collection systems. Further the guidance considers the impact on sortation at a modern automated MRF or PRF, as well as the compatibility of a HDPE packaging item in common HDPE reclaiming processes.
HDPE is used widely in industrial applications and postindustrial HDPE is an important source of HDPE that is collected and recycled.The APR Design® Guide can be a reference when designing industrial applications with HDPE, but not all guidance may be applicable when recyclability of such items is being considered.
The APR’s Recognition Program encourages consumer product, plastic package and package component manufacturers to work with the APR protocols to determine whether new modifications to a regularly recycled plastic package will negatively impact the recycling process prior to introducing the modification.
RESIN IDENTIFICATION CODE, RIC
APR encourages the use of the correct Resin Identification Code symbol of the proper size as detailed in ASTM D7611
ADDENDUM UPDATE
As of March 22nd, 2024 the APR Design Guide and Guidance Table for HDPE have been updated with all of the addendum contents. As of this date, these addendums will no longer be available on our website. All future updates will be made directly into the APR Design Guide and Guidance Table, eliminating the need for separate addendums.
PREFERRED
HDPE base resin for blow molded containers
Melt index between 0.20 and 1.61 g/10min and density between 0.941 to 0.970 g/cm3. Melt index is measured using ASTM D1238 and density measured using ASTM D792.
Ethylene derived from either petroleum or natural renewable products is suitable for the manufacture of HDPE.
HDPE Packages produced with the highest possible level of postconsumer HDPE content are encouraged.
DETRIMENTAL
None specified
RENDERS NON-RECYCLABLE
None specified
REQUIRES TEST RESULTS
Blends of HDPE and other resins
Blends of HDPE and other polymers must be tested to ensure the container is still recognized by NIR Identification as HDPE.
PREFERRED
Unpigmented (Natural) HDPE
Natural material has the highest value as a recycled stream since it has the widest variety of end-use applications. It can be easily identified for food-grade end use applications.
Translucent and opaque colors
HDPE is commonly colored so volumes and markets exist for colored material and it is economical to process.
Colors with L value > 40 or average NIR reflectance > 10%
Colored HDPE is considered preferred if it meets the criteria above which will enable the package to be recognized by NIR (near-infrared) sorting technology used in Material Recovery Facilities (MRFs) and sorted properly to the colored HDPE stream.
DETRIMENTAL
None specified
RENDERS NON-RECYCLABLE
None specified
REQUIRES TEST RESULTS
Colors with an L value ≤ 40 or an average NIR reflectance ≤ to 10%
Sortation testing for dark colors will determine whether a dark colored item will be considered Preferred, Detrimental, or Renders Non-Recyclable.
There is no mechanical property inherent in dark HDPE that makes it unrecyclable. The problem lies in sorting and the physics behind polymer identification. NIR (near-infrared) sorting technology used in MRFs is not capable of identifying many dark colored polymers since the colorant absorbs NIR energy. There are dark shades that may be detected by NIR, and a HDPE label of a different color on a package might aid in detection by NIR. It is not feasible to use manual sorting to separate one dark polymer from another since they cannot be distinguished by sight.
Recent innovations in both black colorants and sortation technology have created the possibility of sortable black HDPE containers. NIR detectable dark/black color concentrates are now available in the marketplace. Companies that are considering such colorants and are unsure of their compatibility with recycling should ask their suppliers to provide APR test results. An item may meet APR Guidance for NIR optical sorting, but may still not be considered recyclable in communities that have chosen in the past to not collect black plastics.
Surveys of reclaimers have indicated that they are willing to purchase bales containing black items. However, it is always advisable to verify markets for new items.
It should be noted that dark colors used in oil bottles and industrial items fall outside the scope of the design guide since they are not typically collected through curbside collection that is the focus of this guidance. Non-NIR sortable HDPE, if collected in a source separated or postindustrial stream, can be reclaimed.
- Size and volume of items within the recycling stream are important features in determining whether something is Preferred, Detrimental or Needs Further Testing. For that reason, this section splits out size and volume based on sortation steps within the recycling process.
- Large Size Boundary:
This boundary exists due to size limits of recycling machinery, particularly automatic sorting equipment, within a Material Recovery Facility (MRF). MRFs typically employ manual sortation before the automatic sort line to remove larger items.
- Small Size Boundary:
This boundary exists due to the minimum sieve size within the glass screens at a Material Recovery Facility (MRF). The mixed material that enters the MRF to be sorted is first compressed/crushed and then passed over these glass screens. The glass screens have small sieve openings where the crushed glass drops through and is sent to the glass recycling stream. However, small plastic packaging items that are below these sieve openings in the glass screens will also drop through to the glass stream and will be lost to the plastic recycling streams.
- 2D/3D Boundary:
This boundary exists due to the separation process that happens in a Material Recovery Facility in order to separate out the paper (2D items) from the containers (3D items) within the stream of mixed materials. If plastic packaging is sorted by the machinery as 2D, it will be sent to the paper stream and will be lost to the plastic recycling stream.
PREFERRED
Large Size Boundary: Large Size Boundary: Items that are ≤ 7.5L (2 gal) in volume
Recycling machinery, particularly automatic sorting equipment, typically cannot process items larger than 7.5 liters (2 gallons).
Small Size Boundary: Items that clearly measure larger than 5 cm (2 in) in any two dimensionsSmall size boundaries are of concern because the industry standard glass screen size for Material Recovery Facilities (MRFs) in North America potentially loses materials less than two inches to the glass stream.
DETRIMENTAL
Large Size Boundary: Items that are > 7.5 L (2 gal) in volume
Recycling machinery, particularly automatic sorting equipment, typically not able to accept items larger than 7.5 liters (2 gallons). Items over this max size are manual pulled out of the recycling stream before the automatic sort equipment to avoid damage.
REQUIRES TEST RESULTS
Small Size Boundary: Items smaller than 5 cm(2 in) in any two dimensions
The industry standard glass screen size for North American MRFs potentially loses materials less than 5 cm (2 in) to the glass stream. Sortation testing below can determine the impact of the size and shape of a container on sortability.
2D/3D Boundary
Sortation testing below can determine if packaging is Preferred or Detrimental
- Large Size Boundary:
PREFERRED
Natural or White Colored Closures on Natural HDPE Bottles
During the reclaiming process, closures are typically not separated from natural/unpigmented HDPE bottles. Since most closures are colored, the pigments from the closures mix with the natural colored plastic of the bottle and cause a color shift. This color shift can limit the potential use of the rHDPE in future applications. To maximize the amount of higher valued natural rHDPE produced, it is best to avoid pigmented closures wherever possible.
Colored closures on Natural HDPE bottles where L value > 40 and Δ E of blend < 3.5
For natural HDPE applications, there should be minimal changes in the color coordinates. The color shift or Δ E can be determined by testing per APR-HDPE-S-01 or Path 1-B per APR-HDPE-CG-01
Primary Material employed to make closure shell, fitment or spout
- HDPE, LLDPE, and LDPE closures when the Melt Flow Index of a blend of the closures and base resin employed for the container is < 4.00 g/10 min.
- Polypropylene closures that are < 10% of the package weight
Polypropylene can be a contaminant in HDPE. When HDPE and PP are melt mixed in an extruder the PP exists as a second phase which can dramatically reduce the impact toughness that is a valuable property of recycled HDPE.
To evaluate the 10% limit, APR guidance is to employ as numerator the sum all the PP employed on a closure, fitment, pour spout, or over-cap employed on a package. Then the denominator is the sum of the PP just mentioned along with the weight of the HDPE used to make the package. Any PP from labels or attachments is ignored in this evaluation.
An allowance for up to 10 wt% polypropylene from closures reflects that the HDPE recycling stream routinely contains PP and reclaimers can manage and accept some PP content in the HDPE stream.
- Closures made of polymers with density > 1.0 g/cm3 that sink in water per APR-O-S-01 and do not contain PVC
Polymers with density greater than 1.0 g/cm3 are expected to sink in the float-sink tank, thereby separating from the HDPE. They also do not damage or wear cutting machinery in the recycling process. Small amounts of these materials that make it through the float-sink process can be melt filtered from the recycled HDPE in the extrusion step. However, these materials are lost to the waste stream in the recycling process and are considered less preferable than an alternative floating attachment that is compatible with HDPE.
Melt Flow Index can be determined using ASTM D1238.
Calculations can be employed as an alternative to laboratory testing to determine what Melt Flow Rate of a blend of two different polyethylene resin is. See APR-RES-MFR-01 for calculations.
Click below for commercially available polyethylene closures that have achieved APR Design for Recyclability Recognition
APR Design® for Recyclability Recognitions
- Any floating olefin-based polymer, or polymer compound, may be employed to make a liner or safety seal on a closure. The following materials are within the scope of floating olefin-based polymers:
- The finished polymer compound, with any additives and color concentrate, has a density less than 0.985 g/cm3, or can be shown to float in water using APR O-S-01.
- Polypropylene, including copolymers with ethylene, impact modified grades, nucleated or clarified grades. Polypropylene in the very small amounts from liners or safety seals have a very minimal negative impact on the HDPE flake. Such attachments that remain with the HDPE throughout the recycling process increase yield and have minimal negative quality impact for the reclaimer.
li>Ethylene polymers and copolymers, including EVA copolymers and ionomers.
- Thermoplastic elastomers based on olefinic constituents. The more common elastomers are ethylene and/or propylene based plastomers/elastomers, as well as olefin block copolymers, including SEBS.
li>Foamed olefin-based materials
- Liners or safety seals/sleeves made of polymers with density >1.0g/cm3 that sink in water per APR-O-S-01 and do not contain PVC
Polymers with density greater than 1.0 g/cm3 are expected to sink in the float-sink tank, thereby separating from the HDPE. They also do not damage or wear cutting machinery in the recycling process. Small amounts of these materials that make it through the float-sink process can be melt filtered from the recycled HDPE in the extrusion step. However, these materials are lost to the waste stream in the recycling process and are considered less preferable than an alternative floating attachment that is compatible with HDPE.
- Liners or Safety seals/sleeves that are designed to be completely removed before the package can be opened
Regardless of material, designs that require complete removal by the consumer of the safety sleeve are Preferred, as the material will not be introduced into the recycling stream.
DETRIMENTAL
Colored closures on Natural HDPE bottles where L value > 40 and Δ E of blend > 3.5
The color shift or Δ E can be determined by testing per APR-HDPE-S-01 or Path 1-B per APR-HDPE-CG-01
Δ E values >3.5 become noticeable in color shift for natural HDPE and are considered detrimental for use in natural (uncolored/non-tinted) applications.
Polypropylene closures that are ≥ 10% of the package weight
APR recognizes that polypropylene is perhaps the most commonly used material for closures.
HDPE packages with PP closures are considered recyclable (as long as all other components are Preferred), but with a Detrimental feature if the weight of the closure relative to the total weight of the package is greater than 10%.
Since polypropylene floats in water like polyethylene it is not separated in the reclaimers float-sink tank. When blended in higher amounts, HDPE it negatively affects the impact properties and can render the material brittle.
Closure liners or Safety Seals that are composites of Aluminum and Paper
These materials will contaminate wash water, will contribute to waste disposal costs, or will stick to the valuable HDPE and reduce quality and value of the final products.
Closures, Closure Liners and Safety Seals that sink in water per APR-O-S-01 and contain PVC materials
PVC is relatively easy to remove in the float-sink tank since it sinks while the HDPE floats. However, the float-sink tank is imperfect and even a very small amount of PVC with the recycled HDPE renders large amounts of it unusable as the PVC degrades at lower temperatures than those at which HDPE is processed.
RENDERS NON-RECYCLABLE
Black or dark colored closures with L value < 40 on natural HDPE bottles
REQUIRES TEST RESULTS
Closures, Liners and Safety Seals made of polymers with density > 1.0 g/cm3 that float water per APR-O-S-01This material passes through the float-sink tank along with the HDPE and is difficult to remove with other methods and can cause contamination if not compatible with HDPE material.
Dispensers, closures or lidding with metal components
Sortation testing for metal components will result in either a Detrimental or a Renders Non-Recyclable ruling. Metal components cannot be Preferred at this time.
Metal contamination is highly undesirable in recycled HDPE. Metals create wear in process machinery, increase operation costs and yield loss, and are a primary source of defects in products made with recycled HDPE. MRFs and HDPE reclaimers use magnets, eddy current separators and metal detectors to keep packages with metal components out of the process stream. Any metal components, such as pump springs, valves, safety sleeves, or lidding that trigger the metal detector will cause the entire plastic item to be removed from the stream and not recycled.
Although metal is easily removed in the float-sink process, most reclaimers have metal detection equipment designed to protect their cutting machinery. Therefore, the container never makes it to the float-sink tank. Large metal items attached to HDPE packages may cause the package to be directed to the metal or waste stream in the recycling process, causing yield loss.
PREFERRED
All plastic dispensers, pumps, and valves are considered preferred when:- Made with PP, HDPE, LDPE, and/or PE copolymers including TPO’s and EVA, TPE elastomers
- All plastic material floats in water after granulation per APR O-S-01.
Click below for commercially available spray dispensers, pumps, and valves that have achieved APR Design for Recyclability Recognition
APR Design® for Recyclability Recognitions
All plastic dispensers, pumps, and valves with density > 1.0 g/cm3 that sink in water per APR O-S-01. and do NOT contain PVC materialsMaterials with densities greater than 1.0 g/cm3 are expected to sink in the float-sink tank, thereby separating from the HDPE. They also do not damage or wear cutting machinery in the recycling process. Small amounts of these materials, with the exception of PVC materials, that make it through the float-sink process can be melt filtered from the recycled HDPE in the extrusion step. However, these materials are lost to the waste stream in the recycling process and are considered less preferable than an alternative floating attachment that is compatible with HDPE.
DETRIMENTAL
All plastic dispensers, pumps and valves with density > 1.0 g/cm3 that sink in water per APR O-S-01 and contain PVC materialsPVC is relatively easy to remove in the float-sink tank since it sinks while the HDPE floats. However, the float-sink tank is imperfect and even a very small amount of PVC with the recycled HDPE renders large amounts of it unusable as the PVC degrades at lower temperatures than those at which HDPE is processed.
RENDERS NON-RECYCLABLE
None specified
REQUIRES TEST RESULTS
All plastic dispensers, pumps and valves with density > 1.0 g/cm3 that float in water per APR O-S-01.
Spray dispensers, pumps or valves may be made of plastics with densities > 1.0 g/cm3 as an alternative to metals. While polymers are generally preferable to metals, the composition of a the polymers may cause it to be incompatible with HDPE recycling.
Companies that are considering such components and are unsure of their compatibility with recycling should ask their suppliers to provide APR test results
Valves or Springs made of Metal
Sortation testing for metal components will result in either a Detrimental or a Renders Non-Recyclable ruling.
Metal contamination is highly undesirable in the HDPE reclaiming process. Metals create wear in process machinery, and increase operation costs and yield loss. While metals sink in the float/sink tank and are therefore easily separable from HDPE flakes, they contribute wear to size reduction machinery. MRFs and HDPE reclaimers use magnets, eddy current separators and metal detectors to keep packages with metal components out of the process stream. Any metal components, such as pump springs, valves, safety seals, or lidding that trigger these devices will cause the entire plastic item to be removed from the stream and not recycled.
PREFERRED
EVOH ≤ 6.0 wt% + PE-g-MAH tie layers with MAH > 0.1 wt% and EVOH:tie layers ratio ≤ 2Ethylene Vinyl Alcohol copolymer (EVOH) is a common layer material used to increase the barrier properties of HDPE packaging. It is not separable in the recycling process and therefore will become part of the recycled HDPE. Maleated polyethylene (PE-g-MAH) tie layers are commonly used in combination with EVOH to improve the adhesion between HDPE and EVOH and have been shown to improve compatibility during the recycling process.
Click below for commercially available EVOH barriers that have achieved APR Design for Recyclability Recognition
APR Design® for Recyclability Recognitions
Fillers, pigments or additives with densities > 1.0 g/cm3 where density of blend with base resin is ≤ 0.97 g/cm3Density is an important property and float-sink tanks are critical separation tools used by reclaimers. Many fillers, pigments and additives used with PE have higher densities and when incorporated into PE can increase the density of resulting PE blend causing it to sink in the float-sink tank. When a PE item sinks during reclamation, the item is lost as waste reducing yield, increasing cost, and thus will be categorized as non-recyclable. The density of an item can be calculated or measured via ASTM D792, ASTM D1505 or ISO 1183-1.
Click below for commercially available fillers, pigments or additives that have achieved APR Design for Recyclability Recognition
APR Design® for Recyclability Recognitions
Workhorse additives that meet the PE blend density of ≤ 0.97 g/cm3Most HDPE in a package contains some form of additives. The "workhorse" additives commonly used have not been shown to cause significant issues with the recycling process or further uses of the recycled HDPE. Commonly acceptable workhorse additives include:
- Thermal stabilizers - These additives typically enhance the further processing of the polymer and are therefore preferred for recycling.
- UV stabilizers – These additives typically enhance the further processing of the polymer and are therefore preferred for recycling
- Nucleating agents
- Antistatic agents
- Lubricants
- Fillers – note that many fillers are dense, so particular attention should be paid to the overall blend density
- Pigments
- Impact modifiers
- Chemical blowing agents
Additive usage should be minimized to maintain the best performance of recycled HDPE for future uses.
Click below for commercially available "workhorse" additives that have achieved APR Design for Recyclability Recognition
APR Design® for Recyclability Recognitions
DETRIMENTAL
Optical brighteners
Optical brighteners are not removed in the recycling process and can create an unacceptable fluorescence for next uses of recycled HDPE. It is difficult to identify material with this negative effect until extremely late in the recycling process where a great deal of added cost has been imparted into a material of low value due to the additive.
EVOH > 6.0 wt% + PE-g-MAH tie layers with MAH > 0.1 wt% and EVOH:tie layers ratio ≤ 2
RENDERS NON -RECYCLABLEL
EVOH > 1% with any other tie layers
Fillers, pigments or additives with densities > 1.0 g/cm3 where density of blend with base resin is > 1.0 g/cm3 or < 51 wt% of the PE blend floats in water per screening test.REQUIRES TEST RESULTS
Fillers, pigments or additives with densities > 1.0 g/cm3 where density of blend with base resin is > 0.97 g/cm3 and < 1.0 g/cm3Workhorse additives where PE blend density is > 0.97 g/cm3Non-HDPE barrier technologies other than EVOH
Testing must show that layers and coatings will either separate and be removed from the HDPE in the recycling process or have no adverse effects on the recycled HDPE in future uses. When used, their content should be minimized to the greatest extent possible. Some layers and coatings have been found compatible with HDPE or are easily separated in conventional recycling systems. Companies that are considering such barrier technologies and are unsure of their compatibility with recycling should ask their suppliers to provide APR test results Critical Guidance recognition letters.
The following barrier technologies require testing to determine an appropriate recyclable category:
• Cyclic olefin copolymers (COC)*
• Cyclic olefin polymers (COP)
• Fluorination*
• Nanocellulose
• Nanoclay
• Oxide coatings
• Polyamide (6, 66, 66/6, and including modified)
• Polyvinyl alcohol (PVOH)*
• Scavengers
• Etc.Click below for commercially available Non-HDPE barriers that have achieved APR Design for Recyclability Recognition
APR Design® for Recyclability Recognitions
Degradable additives
See APR Position Paper on Degradable Additives
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:
- 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.
- 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.
Click below for commercially available polyolefin labels that have achieved APR Design for Recyclability Recognition
APR Design® for Recyclability Recognitions
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 film labels with density > 1.0 g/cm3designed to release from HDPE container in wash and sink in water 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 washWhen 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 labelsPVC, 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 labelsThe 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.
Click below for commercially available labels that exceed the surface area coverage as described in Preferred Guidance section that have achieved APR Design for Recyclability Recognition
APR Design® for Recyclability Recognitions
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.
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 TESTClick below for commercially available label inks that have achieved APR Design for Recyclability Recognition
APR Design® for Recyclability Recognitions
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.
Click below for commercially available direct print inks that have achieved APR Design for Recyclability Recognition
APR Design® for Recyclability Recognitions
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.
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.
Click below for commercially available adhesives that have achieved APR Design for Recyclability Recognition
PREFERRED
Plastic attachments with a density > 1.00 except for PVC
These items sink in the float-sink tank where they are removed from the HDPE and small residual amounts do not severely affect the final product since many of them are melt filtered. PVC is detrimental as discussed elsewhere in this document.
DETRIMENTAL
Paper attachments
The HDPE reclamation process involves a wash step that removes adhesives and other components. This process renders paper into a pulp which is very difficult to filter from the liquid, adding significant load to the filtering and water treatment systems. Some of the small individual paper fibers will remain with the HDPE and carbonize when the material is extruded, causing unacceptable quality degradation.
PVC attachments
PVC sinks in the float-sink tank where the majority of it is removed from the HDPE. Because the float sink tank is imperfect and even a very small amount of PVC entering the extruder causes sever quality and yield problems, this material is detrimental. PVC degrades at HDPE extrusion temperatures and renders large amounts of the recycled HDPE unusable.
Polypropylene attachments
Because polypropylene floats in water, it is not separated in the reclaimers float-sink tank. When blended with HDPE it negatively affects stiffness and impact properties. Although very small amounts of PP, such as that contributed by labels, are regularly accepted by HDPE reclaimers, some attachments comprise a larger weight percentage of the package and therefore a greater negative affect.
RFID’s (radio frequency identification devices) on packages, labels or closures
RFID’s are printed on silver metal, which may create costly waste disposal issues. While RFID’s are small, they may affect HDPE recycling in the same ways as metal labels or other attachments. The use of RFID’s is discouraged as may limit HDPE yield, introduce potential contamination, and increase separation and waste disposal costs.
RENDERS NON-RECYCLABLE
None Specified
REQUIRES TEST RESULTS
Testing must show that these attachments are not adhesively bonded to the package and are made from materials that sink in water so they readily separate from the package when ground and put through a float-sink separation. If adhesives are used to affix attachments, their selection should consider the adhesive criteria within this document.
SCREENING TEST
HDPE Benchmark Test *This test is currently being developed.Metal, metalized and metal-containing attachments
Sortation testing for metal components will result in either a Detrimental or a Renders Non-Recyclable ruling. Metal components cannot be Preferred at this time.
Metal or metal-containing attachments may cause NIR sorters in MRFs to misidentify a HDPE container as metal and direct it to a metal stream, from which it is then discarded. Sorting equipment in the reclaiming process is designed to detect and eliminate metal from HDPE in order to protect cutting machinery. Large items, or items adhesively bonded to the HDPE, can damage the machinery and render the entire package non-recyclable. If small, not detected, or allowed to pass, metals, when used with wash friendly or no adhesive quickly sink in the float sink tank where they are removed from the HDPE.
BENCHMARK TEST
Welded attachments
A certain amount of a welded attachment cannot be separated from the HDPE in the recycling process. These attachments may cause recycled HDPE contamination and yield loss issues in both cases: when the ground section containing both polymers sinks and carries the HDPE with it, or when the ground section floats and carries an incompatible material with the HDPE into the extrusion process. Testing must show that the blend is of a density less than 1.0 so that it floats along with the HDPE in the float-sink tank, and that it is compatible with HDPE in the extrusion process.
SCREENING TEST
