Title - Identification of plastics by use of ‘Resin Identification Code’ - What does the number on plastic mean?
The Society of the Plastics Industry, Inc. (SPI) introduced its resin identification coding system in 1988 at the urging of recyclers around the country. A growing number of communities were implementing recycling programs in an effort to decrease the volume of waste subject to rising tipping fees at landfills. In some cases, these programs were driven by state-level recycling mandates. The SPI code was developed to meet recyclers’ needs while providing manufacturers a consistent, uniform system that could apply nationwide. Because municipal recycling programs traditionally have targeted packaging—primarily containers—the SPI coding system offered a means of identifying the resin content of bottles and containers commonly found in the residential waste stream.
Common Plastic Resins Used in Packaging
|Polyethylene Terephthalate (PET or PETE)||Clarity, strength/toughness, barrier to gas, resistance to grease/oil, stiffness, resistance to heat.||Plastic soft drink bottles, mouthwash bottles, peanut butter and salad dressing containers||Tote bags, dishwashing liquid containers, clamshells, laser toner cartridges, picnic tables, hiking boots, lumber, mailbox posts, fencing, furniture, sweatshirts.|
|2||High Density Polyethylene (HDPE)||Stiffness, strength/toughness, low cost, ease of forming, resistance to chemicals, permeability to gas, ease of processing.||Milk, water and juice containers, grocery bags, toys, liquid detergent bottles.||Recycling bins, benches, bird feeders, retractable pens, clipboards, fly swatters, dog houses, vitamin bottles, floor tile, liquid laundry detergent containers.|
|3||Vinyl (Polyvinyl Chloride or PVC)||Versatility, ease of blending, strength/toughness, resistance to grease/oil, resistance to chemicals, clarity, low cost.||Clear food packaging, shampoo bottles.||Air bubble cushioning, flying discs, decking, film, panelling, recycling containers, roadway gutters, snow plow deflectors, playground equipment.|
|4||Low Density Polyethylene (LDPE)||Ease of processing, barrier to moisture, strength/toughness, flexibility, ease of sealing, low cost.||Bread bags, frozen food bags, grocery bags||Shipping envelopes, garbage can liners, floor tile, furniture, film, compost bins, panelling, trash cans, landscape timber, mud flaps|
|5||Polypropylene (PP)||Strength/toughness, resistance to chemicals, resistance to heat, barrier to moisture, low cost, versatility, ease of processing, resistance to grease/oil.||Ketchup bottles, yogurt containers and margarine tubs, medicine bottles.||Signal lights, battery cables, brooms and brushes, ice scrapers, oil funnels, landscape borders, bicycle racks|
|6||Polystyrene (PS)||Versatility, insulation, ease of processing, low cost, clarity.||Videocassette cases, compact disc jackets, coffee cups, knives, spoons and forks, cafeteria trays, grocery store meat trays and fast-food sandwich containers||Thermometers, light switch plates, insulation, egg cartons, vents, desk trays, rulers, license plate frames, concrete|
|7||Other or OOther plastics, such as acrylic, nylon, polycarbonate, and polylactic acid (a bioplastic also known as PLA), and multilayer combinations of different plastics||These other polymers have a wide range of uses, particularly in engineering sectors||Bottles, plastic lumber applications, headlight lenses, and safety shields/glasses.||These have traditionally not been recycled, though some curb side programs now take them.|