Polythene bags are widely used in many different industries, and these industries include:
The applications for the uses of polyethylene ( polythene ) vary enormously, and one of the more common uses often seen is the everyday plastic bag. Every year millions of tons of plastic bags are manufactured and used for a wide range of applications, and as a result of the environmental impact, most companies now produce biodegradeable plastic. This type of plastic is made using sugar cane, and considered more ' environmentally friendly '.
Polythene is made from crude oil or natural gas which are the main ingredients, and originally it was produced using a high pressure process. Today however, newer types of polythene are usually produced using lower pressures. Granules of the 'raw' material are produced using these processes, and these are then delivered to the polythene bag manufacturing factories in bulk containers or sacks.
The granules are then mixed with additives and any colouring agents if desired, and passed on to the next stage of the bag making process, which is to produce a polythene (tubular) film. This is carried out with the use of a film extruding machine, and the finished rolls of film can be anything up to ten thousand metres in length and weigh up to one hundred kilograms.
Standard polythene bags are produced with one side open and three sides closed. There are two methods of producing these bags, and these are lengthways and sideways.
With the lengthways method the roll or tube of film is laid flat, and pulled through a machine where a hot wire makes a seal across the tube. A tool known as the flying knife cuts the film beneath the seal, while the film is held motionless during the sealing process. In this way the bottom of the bag is formed by the seal, and the folds of the layflat tubing. These are known as bottom-weld bags.
When employing the sideways method, the bags are produced sideways by using a machine with a hot knife to cut and seal the tubular film, and this forms the sides of the bag, the bottom being the fold in the tubular film. These are known as side-weld bags.
The production of polythene bags are usually produced in four stages; raw material, film, printing (optional), and the final product. The final product can be put to many different uses such as:
Eco packing is becoming more and more popular due to its lower impact on the environment. Most manufacturers and retailers stock a wide range of eco-friendly green packaging products, to suit most requirements and help towards a better environment.