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A tube of extruded film being blown to expand. A film blowing machine involves one process used to make plastic film. Extruded tubular processing is most often used with polyethylene films but can be used with other polymers. [1] The film may be laminating film, shrink film, agricultural covering film, bags or film for textiles and clothing ...
The flat film is then wound on a spool before further processing or shipping. The height of the film line is often 10 times the diameter of the blown tube or more; film lines in excess of 30 meters are possible. Once the film tube is completely cooled, it is taken up by several nip rollers.
Blow extrusion of plastic film. The manufacture of plastic film for products such as food packages, shopping bags, and continuous sheeting is achieved using a blown film line. [5] This process is the same as a regular extrusion process up until the die. There are three main types of dies used in this process: annular (or crosshead), spider, and ...
The notion is important, since the higher the frost line, the more difficult to control the uniformity of the film thickness. For example, a higher frost line due to higher melt temperature and/or lower cooling rate means a longer time to solidify, and a more smooth and transparent film is produced.
Extruded film can be stretched, thinned, or oriented in one or two directions. Blown or tubular process forces air into an extruded ring to expand the film. Flat tenter frames stretch the extruded film before annealing. [3] [4] Calender rolls can be used to form film from hot polymers [5] Solution deposition is another film forming process.
In extrusion blow molding, plastic is melted and extruded into a hollow tube forming a tube like piece of plastic with a hole in one end for compressed gas - known as a parison. The parison is captured by closing it into a cooled metal mold. Air is blown into the parison, inflating it into the shape of the hollow bottle, container, or part ...
Blown: the resin is melted and extruded through an annular die, it is air-cooled. This is a slower process but provides for higher cling quality. Blown film is not a consistent extrusion process, leading to inconsistencies across the film web. The cost of production is also higher due to the quantity that can be produced per hour.
COC is commonly extruded with cast or blown film equipment in the manufacture of packaging films. Most often, due to cost, COC is used as a modifier in monolayer or multilayer film to provide properties not delivered by base resins such as polyethylene. Grades of COC based on ethylene show a certain amount of compatibility with polyethylene and ...