The US state of California has published a chemical-based definition for polyethylene terephthalate (PET) plastic, creating a new section in the Public Resources Code on ‘Containers and Packaging’. The definition, approved in ‘AB 906’ Chapter 823, Statutes of 2017, will differentiate PET from polyethylene terephthalate glycol-modified (PETG), and will help improve the efficiency of plastic recycling.
California has required manufacturers of rigid plastic bottles and containers to use a molded label indicating the type of plastic since 1992. There are seven resin codes, defined in Public Resources Code, Division 12.7 Chapter 2 ‘Containers and Packaging’, and they indicate the type of plastic resin being used.
- 1 = PETE (polyethylene terephthalate), commonly known as PET
- 2 = HDPE (high density polyethylene)
- 3 = V (vinyl)
- 4 = LDPE (low density polyethylene)
- 5 = PP (polypropylene)
- 6 = PS (polystyrene)
- 7 = Other (includes multilayer)
Under these codes PETG has traditionally been included under resin code ‘1’. The new definition will differentiate it from PET and so the new rule will exclude it from resin code ‘1’.
PET has several uses and is commonly used for water and soft drink bottles. It is recycled into flakes and pellets, which can be turned into other forms of packaging and fiber, creating products such as carpets and microfibers.
PET differs from PETG in a number of ways. For example, PETG is less brittle and has a softer and more pliable exterior surface. Also, unlike PET, PETG does not have a consistent melting point and becomes molten when heated. When mixed with PET during recycling, under resin code ‘1’, the PETG will melt first, forming a sticky mass that attaches to PET chips. These large clumps of PETG and PET cannot be processed.
California has therefore changed the definition for resin code ‘1’ to exclude PETG. The new definition for PET is:
- Plastic derived from a reaction between terephthalic acid (a) or dimethyl terephthalate (b) and monoethylene glycol (c) and meeting both of the following
- The sum of substances (a) or (b) and (c) constitutes at least 90% of the mass of the monomer reacted to form the polymer
- 225-255 °C melting peak temperature during the second thermal scan with a heating rate of 10 °C/minute (ASTM D3418)
Manufacturers of rigid plastic bottles and containers should be aware that the new regulations will come into effect on October 1, 2018. They are now advised to ensure their products comply with the latest definition for PET.
SGS Food Contact Materials (FCM) Services
With a global network of laboratories, SGS provides analytical testing and consultancy for plastics, including food contact plastics destined for California. Their experts ensure products meet the appropriate regulations for food contact materials and pave the way for compliance. SGS offers the full range of testing, including migration tests, along with expert advice on emerging regulations, compliance issues and documentation review. Learn more about SGS’s FCM Services.
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For further information contact:
Hing Wo Tsang Ph.D
Global Information and Innovation Manager
Tel:(+852) 2774 7420
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