Design for Recyclability: bottles first, thermoforms next?

July 9, 2010

Hello and happy Friday!

And we are back on recycling!

Below is my summary of the Association of Post Consumer Recyclers’ Design for Recyclabilty Guidelines for beverage bottles. The APR does a great job, so I suggest reading the whole report here:

 http://www.plasticsrecycling.org/technical_resources/design_for_recyclability_guidelines/index.asp

For a play-by-play, however, check out my summary below. I feel as though a similar document must be created for PET thermoforms if we ever intend on integrating them into the PET bottle recycling infrastructure. By having PET thermoform Design for Sustainability Guidelines, we could work towards overcoming a lot of the obstacles currently sited as deterrents for the inclusion of said packaging in the PET bottle recovery scheme, like the “look-a-like” syndrome, additives and barriers, adhesives, etc. I honestly see a lot of overlay between these Design Guidelines for PET bottles and my conception of what the Design Guidelines would be for PET thermoforms.

Enjoy!

The Association of Postconsumer Plastic Recyclers

Design for Recyclability Program, Summary

Objective of Guidelines: “To assist plastic bottle designers and fabricators in constructing bottles for specific product applications that are compatible with the broadest range of recycling operations and to enhance the quality and quantity of postconsumer plastic packaging materials” (APR, p. 2).

Design for Recyclability Guidelines, Overview:

  1. Reclamation:
    1. The two most important factors in all reclamation operations are yield and quality.
    2. Any attachment to a plastic bottle, such as closures, closure liners, base cups, inserts, labels, pour spouts, handles, sleeves, safety seals, coatings and layers can impact the recovery rates of the base resin i.e. the resin the bottle is made from, by reducing yield and increasing recycling costs.
    3. These attachments, when not compatible with the base resin being recovered, represent a significant cost to the processor in terms of separation, recovery and waste disposal, and can have an adverse affect on the quality of the PCR produced (APR, p. 7).

Average Reclaimer Yield Values

BOTTLE TYPE                                                                                BASE RESIN YIELD (%)

Two-piece PET soda bottles (w/base cup)                                         65-75 (PET)

One-piece PET soda bottles & custom PET bottles                       75-85 (PET)

Natural HDPE bottles (e.g., milk, water)                                           85-95 (HDPE)

Pigmented HDPE bottles (e.g., soap, detergent)                          75-85 (HDPE)

PVC bottles                                                                                                                  85-92 (PVC)

PP bottles                                                                                                                        85-95 (PP)

Granulation & Air Classification:

    1. Granulation & air classification are generally the first steps in the reclamation process. Following sorting by resin type, whole bottles are ground to a particular size that best suits the reclamation process…Most granulation systems employ an air classifying technique to separate “light” materials such as labels from the heavier base resin being recovered.
    2. Granulation loosens plastic and paper labels and begins to free other attachments that might be on a bottle. Excess glue on labels or attachments has a detrimental impact on granulation and “lights” removal. This increases the cost of reclamation by decreasing the wash cycle yield (APR, p. 8).
  1. Washing:
    1. Washing the ground flake is the next step in most reclamation operations.
    2. Labels, label inks, adhesives, base cups, closures, closure liners, inserts, layers, coatings, or other attachments that may be present in or on the bottle affect washing efficiency and effectiveness.
    3. Labels, labels inks and label adhesives should all be chosen carefully in order not to cause the base resin to be adversely affected.
    4. Labels can contaminate the base resin material; label inks can bleed into the wash water tinting the PCR product; and, label adhesives that can’t be removed can coat the plastic regrind and embed unwanted contaminates.
    5. Adhesives used to affix other attachments can be difficult to remove and should be applied sparingly (APR, p. 8).
  2. Separation
    1. Most conventional reclamation systems use waster in sink/float by hydrocyclone systems to separate the base resin from attachments and contaminants based on differences in the density of the different materials used. 
    2. Plastic resins with densities greater than 1.0 can be separated from resins with densities less than 1.0 in water. However, resins with similar or overlapping densities are difficult to separate in these systems. For example, resins with densities greater than 1.0 cannot be easily separated from each other i.e. PVC from PET.
    3. It is therefore important when selecting plastic resins for attachements or components in a bottle design to avoid any such overlap, or to make them from the same base resin in the same color as the bottle (APR, p. 8).

Density Range of Key Plastics and Closure Materials

MATERIAL                                                                                           DENSITY (g/cc)

PP                                                                                                             0.90 – 0.92

LDPE                                                                                                        0.91 – 0.93

HDPE                                                                                                        0.94 – 0.96

PET                                                                                                           1.35 – 1.38

PLA                                                                                                           1.24 – 1.27

PVC                                                                                                          1.32 – 1.42

PS                                                                                                             1.03 – 1.06

Aluminum                                                                                                        ~2.10

PET bottles (Carbonated Beverage, Water, and Custom Bottles):

  1. Color:
    1. Unpigmented PET has the highest value and the widest variety of end-use applications.
    2. Transparent, green tinted bottles have the next highest value.
    3. Transparent light blue bottles are often included with green or clear streams successfully.
    4. PET bottles with other transparent tinted colors may have limited recycling value and may be considered contaminants by many PET reclaimers.
    5. The use of translucent and opaque color is problematic for many recycled PET end uses because of contamination. In particular, Ti02 is very detrimental to PET recycling for bottle-to-bottle and engineered resin uses.
    6. Inclusion of nucleating agents, hazing agents, fluorescers, and other additives for visual and technical effects should be examined specifically by the reclaiming industry for impact on the overall plastic bottle recycling stream (APR, p. 11).
  2. PVC Attachments:
    1. The use of PVC attachments of any kind on PET bottles is undesirable and should be scrupulously avoided. These attachments generally include, but are not limited to closures, closure liners, labels, sleeves, and safety seals. Very small amounts of PVC can severely contaminate and render large amounts of PET useless for most recycling applications.
    2. In addition, PVC is very difficult to separate from PET in conventional water-based density separation systems, due to similar densities that cause both to sink in these systems (APR, p. 11).
  3. Closures/Closure Liners:
    1. Plastic closures made from polypropylene are preferred to all others, as they are most easily separated from the bottle in conventional separaton systems and create an ancillary stream of recyclable material.
    2. Closter systems that contain no liners and leave no residual rings, or other attachments, on the bottle after the closure is removed are also preferred.
    3. While the use of EVA closer liners in plastic closures is acceptable to many reclaimers, EVA liners can cause contamination problems when used in aluminum closures.
    4. Although tolerated by many reclaimers, the use of aluminum closures should be avoided, as they are more difficult to separate from PET bottles compared to the preferred closure systems (PP, HDPE, LDPE) and add both capital and operating costs to conventional reclamation systems.
    5. Closures made from PS or thermoset plastics are undesirable and should be avoided.
    6. Silicone polymer closure parts are discouraged as they may present significant technical problems in the process of recycling and to the usefulness of the recycled plastic (APR, p. 12).
  4. Sleeves & Safety Seals:
    1. The use of tamper-resistant or tamper-evident sleeves or seals is discouraged as they can act as contaminants if they do not completely detach from the bottle, or are not easily removed in conventional separation systems.
    2. If sleeves or safety seals are used, they should be designed to completely detach from the bottle, leaving no remains on the bottle.
    3. The use of PVC sleeves or safety seals should be avoided.
    4. Foil safety seals that leave foil remnants or attaching adhesive on the PET bottle should be avoided (APR, p. 12).
  5. Labels:
    1. PP, OPP, PE, or other label materials that float in the water are preferred to all other label materials.
    2. Shrink labels with perforations to facilitate separation from bottles are the preferred label systems.
    3. Label materials should not delaminate in the reclaimer’s wash system.
    4. Paper labels are undesirable and should be avoided as they increase contamination in the PET due to fiber and adhesive carry-over through the reclamation process.
    5. Metallized labels increase contamination and separation costs and should be avoided.
    6. In general, the use of plastic labels with a specific gravity of less than 1.0 are preferable for easy removal in conventional water-based density separation systems (APR, p. 12).
  6. Inks and Adhesives:
    1. Some label inks bleed color when agitated in hot water and can discolor PET regrind in the reclaimation process, diminishing or eliminating its value for recycling.
    2. Pressure sensitive labels should be water soluble or dispersible at temperatures between 140 to 180 degrees F in order to be removed in conventional washing and separation systems.
    3. The use of other adhesive types is discouraged and should be avoided.
    4. Adhesive usage and surface area covered should be minimized to the greatest extend possible to maximize PET yield and avoid contamination (APR, p. 13).
  7. Direct Printing/Decoration:
    1. Presently, all direct printing other than date coding, either for product labeling or decoration, contaminates recycled PET in conventional reclamation systems and should be avoided. The inks used in direct printing may bleed ink or otherwise discolor the PET during processing, or introduce incompatible containments. In either case, the value of the PET for recycling is diminished or eliminated (APR, p. 13).
  8. Barrier Layers, Coatings & Adhesives:
    1. Some PET bottle designs require the use of barrier layers, coatings or additives to meet the requirements of specific product applications.
    2. Additives to PET bottles, including scavengers, which cause the PET to discolor and/or haze after re-melting and solid stating, should be avoided unless means are readily and economically available to minimize the effects.
    3. Blends of PET and other resins are undesirable unless they are compatible with PET recycling.
    4. The use of non-PET layers and coatings are undesirable and should be avoided, unless they are compatible with PET or are easily separated from PET in conventional recycling systems.
    5. The use of EVOH, nylon-based, epoxies, amorphous or “diamond-like” carbon, and silicon oxide barrier layers or coatings is currently tolerated be most reclaimers provided the layers-coatings readily separate and can be isolated or have been shown not to be a problem for the reclaiming process.
    6. The use of degradable additives may result in shortening the useful life of the bottles of which they are a part and therefore affect the ability of such bottles to be recycled.
    7. Degradable additives should not be used without an evaluation confirming that their expected use will not materially impair the full service life and properties, including successful recycle and durability, for the next use of the recycled bottle (APR, p. 13).
  9. Base cups/Adhesives:
    1. The use of base cups is undesirable and should be avoided, as they reduce PET yield and increase separation costs.
    2. If base cups are used, the use of unfilled HDPE or clear PET is preferred to all other materials.
    3. The use of other adhesive types is discouraged and should be avoided (APR, p. 14).
  10. Other Attachments:
    1. The use of any other attachment is discouraged.
    2. If any other attachments to a bottle are used, they should be made from HDPE or clear PET.
    3. The use of RFID’s on bottles, labels or closures is discouraged and should be avoided unless they are compatible with PET recycling and are demonstrated not to create any disposal issues based on their material content (APR, p. 14).
  11. Non-detaching Components:
    1. The use of non-detaching bottle components, including monomers, which are not made from PET, must either be compatible with or easily separated from PET in conventional recycling streams (APR, p. 15).

And for fun, below I have attached my most recent understanding of what needs to be determined if we wish to recycle PET thermoforms.

YAY!

Action Plan:

  • Because the demand for PET recyclate exceeds the supply thereby driving up costs for said recyclate, the collection and therefore supply of PCR PET must be increased to facilitate the continued usage thereof.
  • According to a contact, the collection and therefore supply of PET recyclate could be increased as follows:
    • Incorporating PET thermoforms into the existing PET bottle recycling infrastructure;
    • Limit the amount of PET recyclate leaving the country;
    • Impose bottle deposit legislation.

This action plan focuses on the first suggestion; that is, incorporating PET thermoforms into the existing PET bottle recycling infrastructure:

  • We must determine if it is feasible to recycle PET bottles and PET thermoforms together;
  • If feasible, we must determine who is collecting PET thermoforms with bottles for recycling and at what quantities;
  • We must determine what specs exist for mixed PET thermoform and bottle bales;
  • We must determine where these mixed PET thermoform and bottle bales are going i.e. what is the end market of this recyclate?
  • We must determine what sorting technologies are necessary for the separation of PET thermoforms from “look-a-likes;”
  • We need to create local markets for mixed PET bottle and thermoform recyclate.

If it is not feasible to recycle PET thermoforms with bottles, we must determine if it is economically feasible to create a new stream of thermo-grade PET recyclate.

  • We must determine at what quantities, the recycling of PET thermoforms is economically sustainable;
  • We must determine who is collection PET thermoforms for recycling and at what quantities;
  • We must determine what specs exist for PET thermoform-only bales;
  • We must determine what sorting technologies are necessary to isolate PET thermoforms from other “look-a-likes;”
  • We need to create local markets for PET thermoform recyclate.

That’s all for today my packaging and sustainability friends.

But get excited: Yesterday I spoke with the Education Directory of the U.S. Composting Council about what kind of compost would work best for us; he put me in contact with a woman who has been down the zero-waste road before, so expect a lot of good content to come. As a teaser, think waste audits…oh boy!

Tootles!

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