Packaging is increasingly gaining importance in marketing end-products. Its importance can be guaged by the fact that it features prominently along with Product, Price, Promotion, Place: the other four 'P's required for the success of a product. With mini supermarkets and departmental stores mushrooming everywhere, for enhancing convenience to the Indian society, a packaging which projects and protects a product has gained immense popularity. A product packed in a glass-like transparent plastic film certainly improves its chances for increased acceptance and sales.

Shrink wrapping or packaging which adheres tightly over the contours of a product, irrespective of its shape, is a well known application developed in the economically advanced countries.Shrink wrapping can easily be divided into two basic categories:-

	Collation film or thin shrink film
	Industrial or Heavy duty thick shrink film

Thin shrink film is essentially used for consumer products, which are directly marketed to the public, through supermarkets, mini supermarkets or departmental stores. It can consist of packing for a single unit or multiple units.
Heavy duty shrink film is designed to pack industrial items or produce, which are essentially marketed to industries rather than direct consumers.

These two products differ in some critical requirements of the basic film properties.
Thin film - should have an excellent clarity to achieve the desired aesthetics and image of a product.
Heavy duty industrial shrink film requires an excellent impact strength and other mechanical properties to protect products in transportation. Clarity is not considered to be essential.

Polymers suitable for thin film are essentially required to provide excellent clarity. PVC in comparison to PE has better clarity and is therfore more suitable for such applications. On the other hand, PE films provide excellent impact strength and hence are more suitable for heavy duty shrink film applications. Recently, several polyolefinic film compositions with excellent clarity have been developed, which could replace PVC in the thin shrink film segment.

The basic principle of shrink wrapping of plastic films revolves around the fact that all polymer molecules relax after being stressed. The polymers which have a low relaxation behaviour would trend to shrink better compared to those which relax very quickly. In general, amorphous polymers such as PVC, shrink very easily.On the other hand, crystalline polymers like HDPE or PP shrink slowly or shrink less. Among Polyolefins, LDPE, having the least crystallinity, is more suited for shrink film application. Besides, LDPE being very flexible, provides the desired impact / toughness for heavy duty shrink film.

Shrink film requires an application of heat during packing process to relax molecules and thereby induce shrinkability. An application of heat can be made by manual, semi automatic and fully automatic equipments, essentially depending upon the size and complexity of product packaging and speed of conversion. A simplest mode of heating can be attained by the use of Heat guns, similar to dryers used to dry hair. These are very economical and can be used for packing of articles at a lower conversion rate. Indeed, to achieve higher productivity and reduce labour costs, semi automatic or fully automatic shrink tunnels or chambers are required. For heavy duty shrink film, which is used for packing of industrial products, sophisticated shrink tunnels equipments are essential.