Stretch film, also known as stretch film and heat shrink film, is the first in China to produce PVC stretch film with PVC as base material and DOA as plasticizer and self-adhesive effect. Due to environmental protection issues, high cost (relative to PE's high proportion, less unit packaging area), poor stretch-ability, etc., it was gradually eliminated when the domestic production of PE stretch film was started from 1994 to 1995. The PE stretch film first uses EVA as the self-adhesive material, but its cost is high and it has a taste. Later, PIB and VLDPE are used as self-adhesive materials, and the base material is mainly LLDPE. Stretch film can be divided into: PE stretch film, PE stretch stretch film, LLDPE stretch stretch film, PE slit stretch film, etc.   It is produced by using imported linear polyethylene LLDPE resin and special tackifier special additives proportion formula. It can produce multifunctional stretch film for hand use, resistance type machine use, pre-stretch type machine use, anti-ultraviolet, anti-static and anti-rust. It has the following advantages: Using double-layer co-extrusion equipment, the compressed stretch film can maximize the characteristics of each polymer, and its transparency, tensile strength, and perforation resistance are the best when it reaches the melting point. status. 2. It has good stretch-ability, good transparency and uniform thickness. 3. It has longitudinal extensibility, good resilience, good transverse tear resistance, and excellent self-adhesive lap. 4. It is an environmentally friendly and recyclable material, tasteless, non-toxic, and can directly package food. 5. It can manufacture single-sided viscous products, reduce the noise emitted during winding and stretching, and reduce dust and sand during transportation and storage.   1. Sealed packaging This kind of packaging is similar to shrink film packaging. The film wraps the tray around the tray, and then two thermal grippers heat seal the film at both ends. This is the earliest use form of stretch film, and more packaging forms have been developed from this 2. Full width packaging This kind of packaging requires the film to be wide enough to cover the pallet, and the shape of the pallet is regular, so it has its own, suitable for film thickness of 17～35μm 3. Manual packaging This kind of packaging is the simplest kind of stretch film packaging. The film is mounted on a rack or hand-held, and the tray rotates or the film rotates around the tray. It is mainly used for repackaging after the wrapped pallet is damaged, and ordinary pallet packaging. This kind of packaging speed is slow, and the suitable film thickness is 15-20μm; 4. Stretch film wrapping machine packaging This is the most common and extensive form of mechanical packaging. The tray rotates or the film rotates around the tray. The film is fixed on a bracket and can move up and down. This kind of packaging capacity is very large, about 15-18 trays per hour. The suitable film thickness is about 15-25μm; 5. Horizontal mechanical packaging Different from other packaging, the film revolves around the goods, suitable for long goods packaging, such as carpets, boards, fiberboards, shaped materials, etc.; 6. Packaging of paper tubes This is one of the latest uses of stretch film, which is better than the old-fashioned paper tube packaging. The suitable film thickness is 30～120μm; 7. Packaging of small items This is the latest packaging form of stretch film, which can not only reduce material consumption, but also reduce the storage space of pallets. In foreign countries, this kind of packaging was first introduced in 1984. Only one year later, many such packaging appeared on the market. This packaging form has great potential. Suitable for film thickness of 15～30μm; 8. Packaging of tubes and cables This is an example of the application of stretch film in a special field. The packaging equipment is installed at the end of the production line. The fully automatic stretch film can not only replace the tape to bind the material, but also play a protective role. The applicable thickness is 15-30μm. 9. Stretching form of pallet mechanism packaging The packaging of stretch film must be stretched. The stretching forms of pallet mechanical packaging include direct stretching and pre-stretching. Pre-stretching is divided into two types, one is roll pre-stretching and the other is electric stretching. Direct stretching is to complete the stretching between the tray and the film. The stretching ratio of this method is low (about 15%-20%). If the stretching ratio exceeds 55%～60%, which exceeds the original yield point of the film, the width of the film is reduced, and the puncture performance is also lost. Easy to break. And at 60% stretch rate, the pulling force is still very large, for light goods, it is likely to deform the goods.