Packaging materials have become one of the main types of products consumed by industry in the 20th century. There is every reason to suppose that their significance in this century will only increase. A special place among these materials is occupied by a PVC film (polyvinyl chloride).
Packaging should fulfill several functions. Its main purpose is to protect the goods from harmful external influences, pollution, damage during transportation and during the sale process. Other factors that influence the motivations of the buyer are also important, such as the attractive appearance and the belief that no one has used the item he has chosen before and has not even touched it. PVC film compares favorably with polyethylene film with the best optical properties and the ability to use for packaging many food products.
The spread of polyvinyl chloride is facilitated by the relative simplicity of the technology. The granular source material (polymer) enters the extruder, where it melts. Then a large bubble is blown out of it, which serves as a source of a continuous layer, cut to the desired width, and wound around the spools.
The PVC film used in the food industry and trade is produced in two types: stretch and heat-shrinkable. Each of them has its own purpose.
Stretch - PVC film is used to wrap goods around it without creating a weld. It is characterized by special mechanical properties, such as the ability to stretch and interlayer adhesion due to the appearance of an electrostatic field and intermolecular attraction. It is widely used by trading organizations to create hygiene conditions during storage and sale of goods.
PVC shrink film is characterized by its ability to decrease in geometric dimensions under the influence of heat. In order to pack the goods in it, two basic technological operations should be performed: to seal the edges and to set. It is produced in the form of a half sleeve (that is, folded in half in width) or a sleeve wound in rolls. Sealing is performed on industrial welders, most often angular, and sitting, as a rule, is performed by a stream of heated air.
Depending on the nature of the product to be packaged, from the assortment offered on the market, the consumer selects the desired size. The characteristics of shrink film are usually clear on the marking. For example, the PVCT code 400 * 750 * 15 printed on the label means that the roll has a sleeve width of 40 cm, a length of 750 m, and the thickness of one layer is 15 ΞΌm.
Manufacturers of PVC films must indicate the mass. It so happened historically that polyvinyl chloride film is sold by weight.
This type of packaging material also has a drawback - you cannot print text or pictures on the shrink film, since any labels will be distorted when the geometric dimensions are changed. However, it is easy to stick any label on a smooth surface, or, as an option, put it on the bottom. When choosing this method of product registration, it should be remembered that the shrink film creates an external optically transparent layer that reliably protects from scratches, dust, dirt, and gives any glossy gloss even to a faded box.
The marking of a polyvinyl chloride stretch film is about the same as that of shrink film, the difference is that it is wound in one layer, and therefore, as a rule, the length of the roll is twice as long.