Criteria to Consider for PET

The objective of this document is to outline criteria to consider if a variant of the PET bottle is being evaluated for recyclability in the existing PET (SPJ Code “1”) bottle stream. A bottle variant is defined as a bottle accessory such as:

• Closures/Closure Liners
• Label/Adhesives
• Decoration
• Sleeves/Seals
• Basecups/Attachments,
• or the bottle itself

Bottle color, multi-layers and coatings, chemical composition of the PET resin are also evaluated.

The goal of the APR in providing these criteria is to assist PET stakeholders in evaluating the potential impact of the variant on the recycled PET bottle stream towards the end result of maintaining the viability of the recycled PET bottle stream.

This document is to be used for information and guidance purposes only and is mainly directed towards packaging engineers, packagers using PET bottles, manufacturers of bottles and accessories, and resin manufactures. General Guidelines for recyclability for PET soda and custom bottles, as well as other SPI coded bottles, are described in the Association of Postconsumer Plastic Recyclers (APR) “Design Guidelines for Plastic Bottle Recycling” brochure. It is available from the APR (202/974-5419). While the APR design brochure describes PET variants that can have varying degrees of impact (positive and negative) on recyclability, this document focuses in more detail on criteria to consider in evaluating the impact of a variant on the existing recycled PET stream. Using these criteria as general guidelines will assist in the design and execution of appropriate tests and trials to evaluate the effect of a variant. The APR in this document is not addressing the legal issue of what is or is not a “1” SPI coding has legal implications in some state laws.

The question as to what variants of PET can be considered as recyclable in the present postconsumer PET bottle stream is being asked with increased frequency. The growing popularity of PET as a packaging resin and its successful recycling history has led the packaging industry to develop variants of the PET bottle to suit both technical and marketing needs. By and large, PET recyclers, acting independently from each other, have responded to these questions based on their specific recycling process and the requirements of their end products or their customers’ end products. The APR, through this document, is placing before PET stakeholders some general criteria to consider when evaluating the impact of a PET variant on recyclability of the PET bottle stream. The APR encourages those with recyclability questions to contact the APR and the individual PET recyclers listed at the end of this document.

The potential impact of the variant and how to evaluate its impact will depend, in large part, on its effect in one or more of the following major areas:

• Consumer Market
• Collection System
• Recycler’s Process
• Fabricators Process/End Use

Each of these major areas will be discussed in more detail. However, the following assumptions have been made in generating the criteria. The assumptions are:

• The bottle will carry the SPI Resin Identification Code “1’, for PET regardless of the variant or will find its way into the stream as a PET look-alike.
• The new variant will be evaluated as if it were a contaminant in the existing, PET bottle stream while realizing that it may prove to be more recycle friendly than the existing variant.
• The concentration of the variant in the PET bottle stream will not be uniformly distributed and will be tested at levels higher than its expected market penetration.
  

Market information is important because it gives estimates of the expected levels of the variant in the recycled PET stream. These levels are needed to design meaningful trials/tests to evaluate the effect of the variant.

• Generally describe the expected market
• Generally describe type of bottles anticipated. CSD? Custom?
• Expected material type of the bottle?
• Bottle sizes/shapes? Will the bottle be recognized as PET?

The consumer market information above will help stakeholders understand how the variant may or may not impact the collection system.

• Will it fit into a Deposit State system?
• Will it fit into a Curbside system?
• Will modifications be required in the collection infrastructure?
• Will the variant cause the bottle to have look-a-likes that could complicate collection or cause added contamination to the PET stream? For example, would there be PVC look-alikes?
• If so, PVC could increase in the PET stream even though PVC is SPI Code “3”?
• In the case of a PET chemical variant, could the variant have inherently more value than PET if sorted from the stream? Would the sorting be done at a MRF or recycler?

The level of the variant that a recycler experiences at any given time can depend on the source of the recycled PET bottles, There are four general sources of baled PET bottles, the makeup of which varies significantly between the general sources but also within a general source. The general types are:

Deposit Bale:
Generally the highest quality, mainly
PET soda bottles

Curbside Bale:
Lower quality than deposit bale, a mixture of PET soda bottles (main component) and custom PET bottles.

Deposit Curbside Bale:
Quality varies but similar to curbside, main component is custom PET bottles with some PET soda bottles

Mixed Bale:
Quality varies, composed of a mixture of PET soda and custom bottles, homopolymer HDPE (milk containers) and copolymer HDPE (detergent containers).

Consideration should be given to the variants impact on each of a recyclers sorting and cleaning processes. Of course, each recycler’s process differs, so all of the items listed below will not apply to every recycler.

• Baling/Debaling
• Automated technology and manual sorting techniques to sort colors and contamination such as PVC
• Whole bottle washing
• Granulation (dry and wet)
• Dry label separation
• Washing equipment/wash chemistry
• Wastewater
• Solid wastes
• Air quality
• Screening loss
• Is the cost to recycle impacted? New equipment? New wash chemistry? Productivity changes?
• Is the value of the clean flake or melt filtered pellets impacted to include:
  • Particulates;
  • Gel formation
  • Screen life
  • Color
  • IV
  • Safety issues such as volatiles from degraded variant
    • Are new test methods required to determine levels or residual levels of the variant?

The fabricator of a product may be a recycler using internally generated recycled PET or one who uses recycled PET from the marketplace. The major end uses of recycle PET are:

• Fiber
  • Bottle, Food and Non-Food
  • Sheet/Film thermoformed Sheet
  • Strapping
  • Engineering Resins
  • Chemical Recycling

The effect, if any of the variant, whether purposely left in the stream or resulting from incomplete removal, should be evaluated using different test protocols for each use.

Criteria to consider for evaluating the impact of the variant will depend in large part on the particular end use. A screening criterion for any end use is to determine if the cleaned flake containing the expected amount of the variant is transparent in the melt. If the melt or resulting amorphous pellet is not transparent, it indicates that the variant is not technically compatible with PET, and may adversely effect an end use. The level of the variant should be tested in the end uses at some multiple of its expected market penetration to account for non-uniform distribution. Multiples of 2 to 10 have been suggested and used.

Following are criteria to consider for the listed end uses.

Fiber includes fiberfill, carpet and textile grades of fiber.

• Impact on flake or chip handling processes to include drying and fines generation
• Impact on screen life (if flake used)
• Impact on fiber spinning/processing
• Impact on fiber properties to include:
  • Tensile strength
  • Elongation
  • Modulus
  • Color
  • Dyeability
  • Fluorescence
  • Toughness/Abrasion resistance
  • Shrinkage
  • UV/Weather resistance
  • Crystallinity
    

The bottle market includes CSD and custom containers for food and non-food applications. Also consideration should be given to monolayer versus multi-layered constructions.

• Impact on flake/chip handling
• Impact on screen life (if flake used)
• Impact on injection molding process
• Impact on stretch blow molding process
• Impact on container properties to include:
  • Physical properties
  • Color
  • Visual
  • Haze
  • Barrier properties
  • Taste
  • Thermal properties
    

• Impact on flake/chip handling
• Impact on screen life (if flake used)
• Impact on extrusion/processing
• Impact on thermoforming process
• Impact on properties

• Impact on flake/chip handling
• Impact on screen life (if flake used)
• Impact on extrusion/processing
• Impact on properties
  

• Impact on flake/chip handling
• Impact on screen life (if flake used)
• Impact on extrusion/compounding process
• Impact on properties to include:
  • Physical
  • Electrical
  • Thermal
  • Crystallization
    

The potential chemical recycling processes include methanolysis, glycolysis, hydrolysis, and saponification. The ability of these processes to handle variants will differ significantly. Test protocols are designed to fit each type of technology.