Basic kinds of hard polymer films
applied by the firm "Langa" to the production of blister packages, correxes, pans and trays for food products:
PET - polyethylene terephthalate, or terrylene film
PVC - polyvinylchloride film
Above kinds of hard polymer films are good for thermoforming, provide for a wide color gamma, allow having the most complex design solutions in the field of packing put into practice.
At the same time, it should be pointed out that the application of certain polymer films (such as PVC, polystyrene) is restricted by the laws of European countries.
Thus for instance, it is forbidden in Germany and some other European countries to apply PVC to the package manufacture because its utilization is impossible without doing environmental damages. PVC film is harmless to food products, but it emanates chlorine during burning. Refusal of burning does not solve the problem as it degrades with the poison emanation to the soil.
There are restrictions also to the use of polystyrene for food packages. During storage, even short-time, of food products in a polystyrene package (such as chocolate sweets in correxes), styrene emission begins. The chocolate just absorbs styrene, which is harmful to the human health.
PET is the most expensive raw material for the food package manufacture. But the film has a higher molecular mass (20 000 - 40 000), which excludes emission of any harmful substances from the material. The base of polymer produced by polycondensation of terephthalic acid or its dimethyl ether with ethylene glycol initially does not give rise to environmental damages on degrading.