In my most recent post I discussed recycling codes (those little triangles with numbers on the botom of a container). So I thought today I’d provide buyers with a brief history of them as it surely impacts your job and is something you should understand.
SPI (The Society of the Plastics Industry) codes were developed to meet all recyclers’ needs and also provide manufacturers a consistent, uniform system that could be applied across the country. Most if not all municipal recycling programs target all types of packaging containers. The SPI code offers a way to identify the specific resin content of bottles and containers commonly found in the residential waste. Let’s take a look at the first four.
2. High Density Polyethylene (HDPE). HDPE is used to make bottles for milk, juice, water and laundry products. Unpigmented bottles are translucent, have good barrier properties and stiffness, and are well suited to packaging products with a short shelf life such as milk. Because HDPE has good chemical resistance, it is used for packaging many household and industrial chemicals such as detergents and bleach. Pigmented HDPE bottles have better stress crack resistance than unpigmented HDPE bottles.
3. Vinyl (Polyvinyl Chloride or PVC). In addition to its stable physical properties, PVC has excellent chemical resistance, good weatherability, flow characteristics and stable electrical properties. The diverse slate of vinyl products can be broadly divided into rigid and flexible materials. Bottles and packaging sheet are major rigid markets, but it is also widely used in the construction market for such applications as pipes and fittings, siding, carpet backing and windows. Flexible vinyl is used in wire and cable insulation, film and sheet, floor coverings synthetic leather products, coatings, blood bags, medical tubing and many other applications.
4. Low Density Polyethylene (LDPE). Used predominately in film applications due to its toughness, flexibility and relative transparency, making it popular for use in applications where heat sealing is necessary. LDPE is also used to manufacture some flexible lids and bottles and it is used in wire and cable applications.
During tomorrows post we will discuss the final three codes and some thoughts as to what they mean in your work.
We look forward to and appreciate your comments.