Classification of plastic films1

There are no uniform regulations for the classification of films. Usually people are used to the following three classification methods: (1) Classification according to the raw materials used in film forming: polyethylene film, polypropylene film, polyvinyl chloride film and polyester film, etc. (2) Classification by film use: there are agricultural films (here, according to the specific use of agricultural films, they can be divided into mulch film and greenhouse film); packaging films (packaging films can be divided into food packaging films and various industrial products according to their specific uses. packaging films, etc.) and breathable films for special environments and special purposes, water-soluble films and films with piezoelectric properties, etc. (3) According to the film forming method: there are films that are extruded and plasticized and then blown and formed, which are called blown films; films that are extruded and plasticized, and then the molten material is cast and formed from the die mouth, are called cast films. ; A film made of plasticized raw materials by several rollers on a calender is called a calendered film.