Everything You Need to Know About Plastics for Cannabis Packaging

At AssurPack^®, we love package engineering.

So we tend to forget that most people in the cannabis industry aren’t as passionate about child-resistant closure mechanisms — or plastics — as we are.

However, there are a few facts about plastic that can help you make good choices for your packaging in terms of functionality, sustainability, and cost-efficacy.

We’ve organized this quick guide to plastics by their SPI codes — those are the recycling numbers you see on the bottoms of bottles. You’ll also find some insights about bioplastics.

So, without further ado, here are the most common plastics you’ll see on the market.

Polyethylene Terephthalate

• Recycling SPI Code: #1 — Recyclable
• Abbreviation: PETE or PET
• Food-grade: Yes
• Popular Uses: soda bottles, rope, peanut butter jars
• Popular Reuses: carpeting, pillow stuffing, luggage
• AssurPack® Products: AssurClam®, AssurPro® Carton

As a widely used fiber in clothing, polyethylene terephthalate (PET) is a naturally colorless thermoplastic polymer. You might hear it referred to as simply “polyester.” It’s shatter-proof and extremely strong for its weight.

PET has a good environmental profile. It’s non-toxic, and it’s easily reclaimed for new PET products. However, in the United States, only 31% of PET gets recycled, which means about 4.8 billion pounds of PET enters our landfills and oceans annually.

We put PET to good use in our popular AssurClam^® and the AssurPro^® carton because it’s safe, strong, and inexpensive. These products feature sustainably harvested paperboard too, which means — if they’re properly recycled — AssuClam^® and AssurPro^® Carton have minimal environmental impact.

High-Density Polyethylene

• Recycling SPI Code: #2 — Recyclable
• Abbreviation: HDPE
• Food-grade: Yes
• Popular Uses: milk jugs, shampoo bottles, bleach containers
• Popular Reuses: crates, decking lumber

Like PET, high-density polyethylene is also used for beverage bottles — and gas tanks, bread bags, and hundreds of other packages. The versatile polymer can be modified into a rigid form (for milk jugs or lumber) or used as a flexible wrap for grocery sacks. Both forms are recyclable.

Polyvinyl Chloride

• Recycling SPI Code: #3 — Recyclable, special facilities
• Abbreviation: PVC
• Food-grade: No
• Popular Uses: plumbing pipes, window frames
• Popular Reuses: flooring, siding, imitation leather

You won’t see polyvinyl chloride (PVC) used very often in the world of consumer packaged goods. The #3 plastic outgases toxins, making it unacceptable for most food applications. However, nearly all of the world’s sewer piping is PVC, and it finds use as insulation for electrical cables, inflatable pool toys, and credit cards.

Low-Density Polyethylene

• Recycling SPI Code: #4 — Recyclable, special facilities
• Abbreviation: LDPE
• Food-grade: No
• Popular Uses: sandwich bags, squeeze bottles for honey, grocery bags
• Popular Reuses: garbage cans, decking lumber

First discovered in 1933, low-density polyethylene (LDPE) remains vital today, despite competition from modern plastics. Its internal molecular structure is weaker — and its tensile strength is lower — but LDPE has higher resilience and flexibility than other plastics.

Shrinkwrap, soft snap-on lids, six-pack rings, trays, and other parts that need flexibility are often LDPE. It’s also the cellular packing foam that protects premium products like electronics.

Polypropylene

• Recycling SPI Code: #5 — Recyclable, special facilities
• Abbreviation: PP
• Food-grade: Yes
• Popular Uses: amber-colored prescription bottles, bottle caps, Tupperware
• Popular Reuses: ice scrapers, rakes
• AssurPack^® Products: MarBox-CR^®, AssurTin^® (lid)

Similar to polyethylene but harder and more heat resistant, polypropylene (PP) is resistant to heat and organic solvents. Its heat resilience makes it perfect for medical devices that require sterilization in an autoclave.PP is also useful for living hinges such as those found on preroll tubes and the AssurPack MarBox-CR^® and AssurTin^®. When the molecular chains are oriented across the fold, a PP hinge can easily withstand thousands of openings and closings.

Polystyrene

• Recycling SPI Code: #6 — Multiple variants, some recycle
• Abbreviation: PS
• Food-grade: Yes
• Popular Uses: plastic cutlery, packing peanuts, disposable coffee cups
• Popular Reuses: rulers, insulation
• AssurPack^® Products: SecurSlide^® (clear portion)

Polystyrene (PS) is a versatile polymer available as a rigid plastic or expanded foam. 

In its solid form, PS is naturally clear, making it perfect for CD jewel cases and disposable test tubes, and it can also be mixed with colorants, as in the case of our SecurSlide^® package. PS can be thermoformed with a vacuum or injection molded with great accuracy. 

Expanded polystyrene (EPS) is an effective thermal barrier for drink coolers and building materials. Commonly known under the trade name Styrofoam, EPS does not recycle and does not biodegrade. Sadly, due to its overuse as a packaging material, polystyrene foam accounts for 35% of landfill material in the United States and litters the beaches of every ocean in the world.SecurSlide^® is made with high-impact styrene (HIPS). HIPS is modified to increase styrene’s brittleness, making the SecurSlide^® a robust package for prerolls and mints. In fact, customers often keep the package to use again and again.

Miscellaneous Plastics

• Recycling SPI Code: #7 — Some types are recyclable
• Includes: polycarbonate, acrylic, nylon, fiberglass composite
• AssurPack^® Products: SecurSlide^® (clear portion)

The #7 SPI code is a catch-all for many types of plastic, most of which do not recycle. 

The clear portion of the SecurSlide^® is formed from a #7 plastic that does recycle — acrylonitrile butadiene styrene (ABS). It’s the same plastic used to make LEGO^® bricks. ABS is remarkably impact-resistant and relatively inexpensive, which helps keep our costs down — along with yours.

The #7 label spans plastics including ABS, nylon, acrylic, and types of styrene, yet polycarbonate (PC) is the most prevalent. 

PC is a frequent favorite for reusable water bottles despite the bisphenol A (BPA) present in the material. BPA is an endocrine disruptor that may increase estrogen levels and levels and cause cancer in humans. It’s one reason ABS is a better solution for AssurPack^® products — and kids toys like LEGO^® bricks.

Bioplastics and Biodegradability

Plastics are a versatile solution, but they’re also a problem. The world demands about 200 million tons of plastic each year and only a fraction of it reenters the supply chain as recycled material. 

Bioplastics can help. Bioplastics are made with natural polymers from agricultural sources such as corn starch. They represent an increasing percentage of the plastics market, and they solve a lot of problems. 

Bioplastics can:

• Reduce our carbon footprint
• Lower the consumption of non-renewable materials (petroleum)
• Eliminate harmful additives such as BPA
• Preserve food without altering its flavor or scent

Polylactic acid, commonly referred to as PLA, is made from fermented starch from crops such as corn and potatoes. PLA is compostable — meaning microbes can break it down over months-long periods — but it is not biodegradable. Under normal conditions, without the microbes, it behaves like a normal plastic and won’t break down.

PLA may cause some problems too. Its acidity may affect the pH of our water and soil as it decomposes, and some experts believe that purposefully cultivating crops for plastic may impact food production. Special facilities are required for composting most “biodegradable” plastics. Moreover, people may simply throw bioplastic away if they believe it’s ecological to do so.

Designing Around the Problem

We want to bring you real-world solutions to environmental problems. That’s why we introduced the SecurSlide^® BP. The SecurSlide^® BP is made with a combination of conventional plastic and 50% wheat resin for sustainability. Instead of requiring specialized composting facilities, the bioplastic can reenter the recycling stream as normal, #7 plastic.

With 50% conventional plastic in the mix, the SecurSlide^® BP maintains the structural integrity of virgin material but with half the footprint. And because customers tend to reuse the SecurSlide^® for other purposes, your packaging may stay out of landfills indefinitely.

If you’re marketing prerolls, mints, or even concentrates, check out the SecurSlide^® BP now. We offer a variety of liners and fluting to suit your needs and please your customers.And for more information on sustainable packaging, make sure to check out our Guide to Sustainable Cannabis Packaging.