Tuesday, April 5, 2011
Identification in plastics! Check It!!
"In general, plastics that are marked with recycle codes 1, 2, 4, 5, and 6 are very unlikely to contain BPA. Some, but not all, plastics that are marked with recycle codes 3 or 7 may be made with BPA." 
There are seven classes of plastics used in packaging applications. Type 7 is the catch-all "other" class, and some type 7 plastics, such as polycarbonate (sometimes identified with the letters "PC" near the recycling symbol) and epoxy resins, are made from bisphenol A monomer.
Type 3 (PVC) can also contain bisphenol A as an antioxidant in plasticizers. This is particularly true for "flexible PVC", but not true for PVC pipes.
The SPI resin identification coding system is a set of symbols placed on plastics to identify the polymer type. It was developed by the Society of the Plastics Industry (SPI) in 1988, and is used internationally. The primary purpose of the codes is to allow efficient separation of different polymer types for recycling.
The symbols used in the code consist of arrows that cycle clockwise to form a rounded triangle and enclosing a number, often with an acronym representing the plastic below the triangle. When the number is omitted, the symbol is known as the universal Recycling Symbol, indicating generic recyclable materials. In this case, other text and labels are used to indicate the material(s) used. Previously recycled resins are coded with an "R" prefix (for example, a PETE bottle made of recycled resin could be marked as RPETE using same numbering).
Contrary to misconceptions, the number does not indicate how hard the item is to recycle, nor how often the plastic was recycled. It is an arbitrarily-assigned number that has no other meaning aside from identifying the specific plastic.
The Unicode character encoding standard includes the resin identification codes, between code points U+2673 and U+2679 inclusive. The generic material recycling symbol is encoded as code point U+267A.