Extrusion & Film Blowing
There are several stages in making any polythene product.
Polyethylene, or polythene is an oil derivative and was first used in the 1930s. Crude oil or natural gas is 'cracked' into several commonly known products, including petrol. One such product, Ethylene, is then subject to heat and other catalysts - the end result is polyethylene in a granular form.
Lincoln Polythene Ltd sources polyethylene in granular form direct from major petro-chemical companies. These granules are then sent through a film extrusion machine. The granules are heated to a molten state and forced through a die. The molten polyethylene is subject to air and appears from the die in the form of a circular tube.
This molten tube has air blown into it - two nip rollers pull the tube upwards. Emerging beyond the nip rollers still as a flattened tube (known as Lay Flat Tubing) this tube can be wound onto a cardboard or plastic core.