Ordinary polyester is a crystalline polymer, and ordinary PET film can only achieve a thermal shrinkage rate of less than 30% after special processing. To obtain a polyester film with a higher thermal shrinkage rate, modification must also be carried out. That is to say, in order to prepare a polyester film with a high thermal shrinkage rate, ordinary polyester, namely polyethylene terephthalate, needs to be polymodified. The maximum thermal shrinkage rate of polymer-modified PET film can be as high as more than 70%.

Characteristics of heat-shrinkable polyester film: It is stable at room temperature, shrinks when heated (above the glass transition temperature), and more than 70% of the thermal shrinkage occurs in one direction. The advantages of heat-shrinkable polyester film packaging are: ① Skin-fitting and transparent, reflecting the product image. ②Tightly tighten the packaging to prevent loosening. ③Rainproof, moisture-proof and mildew-proof. ④No restorability and certain anti-counterfeiting function. Heat-shrinkable polyester film is often used in convenience food, beverage markets, electronic appliances, and metal products. In particular, shrink labels are its main application areas. Because with the rapid development of PET beverage bottles, beverage bottles such as Coke, Sprite, and various juices require PET heat shrinkable films to be used as heat seal labels. They are both polyesters, environmentally friendly materials, and easy to recycle. use.

In addition to being used as shrink labels, heat-shrinkable polyester film has begun to be used in the outer packaging of daily commodities. Because it can not only protect packaged items from impact, rain, moisture, and rust, but also enable products to win users with beautifully printed outer packaging. At the same time, it can well demonstrate the good image of the manufacturer. More and more packaging manufacturers use printed shrink films to replace traditional transparent films. Because printed shrink film can improve the appearance of the product, is conducive to product advertising, and can make the trademark brand have a deep impression in the minds of consumers.