Bag Folding Shopping

Plastic shopping bags , carrier bags or plastic grocery bags are a common type of shopping bag in several countries. Most often these bags are intended for a single use to carry items from a store to a home: reuse for storage or trash (bin bags) is common. Heavier duty plastic shopping bags are suitable for multiple uses as reusable shopping bags.

History

Plastic bags are often made from polyethylene, which consists of a long chain of ethylene monomers. Ethylene is derived from natural gas and petroleum.

Patent applications relating to the production of plastics shopping bags can be found dating back to the early 1950s in the US and Europe, but these refer to composite constructions with handles fixed to the bag in a secondary manufacturing process.

The lightweight shopping bag as we know it today is the invention of Swedish engineer Sten Gustaf Thulin. He developed his idea for forming a simple one-piece bag by folding, welding and die-cutting a flat tube of plastic in the early 1960s for packaging company Celloplast of Norrkoping, Sweden. His idea produced a simple, strong bag with a high load carrying capacity and was patented worldwide by Celloplast in 1965.

Celloplast was a well established producer of cellulose film and a pioneer in plastics processing. The company's patent position gave it a virtual monopoly in plastics shopping bag production and the company set up manufacturing plants across Europe and in the US. However, other companies saw the attraction of the bag, too, and US petrochemicals group Mobil overturned the Celloplast US patent in 1977.

The Dixie Bag Company of College Park, Georgia, owned and operated by Jack W. McBride ("The Bagman") was one of the first companies to exploit this new opportunity to bring convenient products to all major shopping stores. Mr. McBride's, Dixie Bag, as well as Houston Poly Bag and Capitol Poly Bag, were instrumental in manufacturing, marketing, and perfecting this unique bag by the early 1980s. Kroger, an Atlanta-based company, agreed to try this innovation. So, the real change in grocery bags did not start until 1982, when the two of America’s largest grocery companies Safeway and Kroger started replacing paper bags with more affordable plastic bags.

Without its plastics bag monopololy, the Celloplast business went into decline and the company was split up during the 1990s. The Norrkoping site remains a plastics production site, however, and is now the headquarters of Miljösäck, Sweden’s largest producer of waste sacks manufactured from recycled PE.

From the mid 1980s on, the usage of plastic bags became common for carrying daily groceries from the store, to our vehicles, and finally to our homes. As plastic bags increasingly replaced paper bags, and as other plastic materials and products replaced glass, metal, stone, timber and other materials, a packaging materials war erupted with plastic shopping bags at the centre of highly publicised battles.

Composition

Plastic shopping bags are usually made of polyethylene. This can be low-density, resin identification code 4, or most often high-density, resin identification code 2. Most plastic bags are derived from natural gas.

Alternatives

Although not in use today, plastic shopping bags could be made from Polylactic acid (PLA) a biodegradable polymer derived from lactic acid. This is one form of vegetable-based bioplastic. This material biodegrades quickly under industrial composting conditions and does not leave toxic residue. However, bioplastic can have its own environmental impacts, depending on the way it is produced. Recyclability of this experimental material is unproven: resin identification code 7 is applicable.

Bags can also be made from degradable polyethylene film. A variety of mechanisms are available to promote degradtion under specific conditions of sun and moisture. One uses a blend of plant-derived thermoplastics starch and degradable polyesters (which can be produced from either petrochemical or plant sources). Most degradable bags do not readily decompose in a sealed landfill and represent a possible contaminant to plastic recycling operations. Resin identification code 7 is applicable.

Environmental concerns

Many people have concerns about littered plastic shopping bags: littered bags are unsightly and can create a hazard to animal life. Efforts are underway to control excess usage, reduce littering and to increase reuse and recycling. Littering is often a bigger problem in developing countries, where trash collection infrastructure is less developed, than in developed nations.

Reuse

Heavy duty plastic shopping bags are suitable for reuse as reusable shopping bags. Lighter weight bags are often reused as bin bags (trash bags) or to pick up pet faeces. All types of plastic shopping bag can be recycled into new bags where effective collection schemes exist.

Recycling

Although the United States Environmental Protection Agency stated in 2000 that only 1% of plastic bags were recycled, significant attention resulted in a 700% growth in the recycling industry as new capacity led to a 7% rate. This resulted in more than 800 million lbs of bags and other film being recycled in 2007 alone Each ton of recycled plastic bags saves the energy equivalent of 11 barrels of oil, although most bags are produced from natural gas derived stock. In light of an Australian study showing more than 60% of bags are reused as bin liners and for other purposes, the 7% recycling rate account for 17.5% of bags available for recycling.

References

^ European Plastics News: Plastic T-Shirt Carrier Bag (1965)
^ ^a ^b Natural Resource Defense Council
^ US Department of Energy, National Renewable Energy Laboratory, US Life Cycle Inventory Database, http://www.nrel.gov/lci/
^ Notes from the Packaging Laboratory: Polylactic Acid -- An Exciting New Packaging Material
^ The Guardian - biodegradable plastic bags carry more ecological harm than good
^ http://www.americanchemistry.com/s_plastics/sec_content.asp?CID=1593&DID=8899
^ Questions About Your Community: Shopping Bags: Paper or Plastic or . . .?
^ http://www.environment.gov.au/settlements/publications/waste/plastic-bags/pubs/report-2002.pdf

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