Packaging materials have become one of the maintypes of products consumed by industry in the XX century. There is every reason to believe that their significance in the present century will only increase. A special place in a row of such materials is occupied by a PVC film (polyvinylchloride).
Packaging must perform several functions.Its main purpose is to protect the goods from harmful external influences, pollution, damage during transportation and in the process of sale. Other factors that influence the incentive motivations of the buyer are important, such as an attractive look and the belief that no one previously enjoyed the thing that was admired or even touched it. PVC film advantageously differs from polyethylene by the best optical properties and the ability to use for packing many food products.
The spread of polyvinyl chloride is promotedrelative simplicity of technology. The granular starting material (polymer) enters the extruder, where it is melted. Then a large bubble is blown out of it, serving as a source of a continuous layer, cut to the desired width, and wound onto a bobbin.
PVC film, used in the food industry and trade, is made of two types: stretch and heat shrinkable. Each of them has its own purpose.
Stretch - PVC film serves towrap it with goods 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 hygienic conditions for the storage and sale of goods.
PVC shrink film is characterized by its abilityto decrease in geometric dimensions under the influence of heat. In order to package the goods, you must perform two basic technological operations: to seam the edges and to seat. It is produced in the form of a half-sleeve (that is, folded in half in width) or a sleeve wound on rolls. Sealing is performed on industrial welders, most often corners, and the shrinkage is usually carried out by a stream of heated air.
Depending on the nature of the goodspackaging, from the range offered on the market, the consumer chooses the right size. The characteristics of the shrink film are usually clear by labeling. For example, the PVCT code 400 * 750 * 15 printed on the label means that the roll has a half-sleeve width of 40 cm, a length of 750 m, and a thickness of one layer is 15 μm.
Manufacturers of PVC films necessarily indicate mass. It so happened historically that a polyvinyl chloride film is sold for weight.
Is this type of packaging materials andThe disadvantage is that you can not print text or pictures on a shrink film, because when you change the geometric dimensions, any inscriptions will be distorted. However, it is easy to glue any label on a smooth surface, or alternatively, place it underneath. When choosing this method of product design, it should be remembered that shrink film creates an external optically transparent layer that reliably protects against scratches, dust, dirt, and imparts glossy shine to any, even faded box.
The polyvinyl chloride stretch film is about the same as 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 large.
