High polymer materials such as rubber, plastic and fiber will have a certain shrinkage under a certain temperature. Most products are required to have a good thermal stability and small shrinkage, but some products ate required to have a large shrinkage when heated . The performance that high polymer materials will shrink by heating is opposite to that of metal materials . Taking advantage of this performance .we make the high polymer materials into heat-shrinkable rubber boot,heat-shrinkable membrane plastic,heat-shrinkable fiber and fiber-knitting which will be used for packging .

The heat-shrinkable membrane plastic is widely used recent years with the advantage of its transpatency,multiple variety,abound raw materials,ease of producing and using ,The table 1 shows the main performance and the application of the heat-shrinkable membtane plastic.

Besides the variety in table 1,,PA,PA,PET,PVCD, EVA etc also can be made into the heat-shrinkable membrane plastic, it is requirded that the hea-shrinkable membrane plastic be stable under normal temperature and shrink when heated. The characteristics of the heat-shrinkable membrane plastic : ①The transpatency help to present the figure of the product.②Intensive and firm, prevent from the flowability. ③Small package capacilty reduce the storage and shipment cost.④Shower-proof,damp-proof and anti-fungus. ⑤Healthy and ease of clearing . ⑥ Nonrelease, ensure the prevention of fake and burglary. ⑦Various specification of membrane and wide choices.⑧Recycle used and do no harm to the environment .