Wuhan Handern Blown Film
DATE：2020/8/28 8:34:37 / READ： / SOURCE：This station
Wuhan Handern Blown Film
The film produced by the extrusion blow molding method is cylindrical, which is convenient to produce bags with a heat sealer or cut and unfold into flat films. Due to the simple process of blown film, low cost, and suitable for molding processing of a variety of thermoplastics, it has developed rapidly. Item
Previously, blow molding has become the main production method for polyolefin films. www.handern.net Breathable film production line
1. Blown film die and auxiliary machine
1. Extrusion method of blown film
The end of the extruder is equipped with a die with an annular slit. The molten resin is extruded from the die into a cylindrical film tube. At the same time, a certain amount of compressed air is blown into the film tube to expand it. Air is sprayed around it or other special methods are used to cool and solidify the molten resin, and then the film tube is passed through a stabilizing plate, folded by a clamping rod, and then taken up. www.handern.net Breathable film production line
According to the direction of film introduction, it can be divided into flat extrusion upward blowing method, flat extrusion flat blowing method and flat extrusion downward blowing method. The up-blowing method is the most widely used, especially
Wide-width films of PVC and PE are mostly processed by this method (as shown in Figure 9-32): The down-blowing method is generally associated with water cooling, and is often used for high-crystallinity plastics such as PP and PA to reduce crystallinity and improve transparency. ; The flat blowing method is more convenient to operate, but the upper and lower parts of the film bubble are not uniformly cooled, and the film tube sags due to its own weight, which affects the thickness uniformity, so it is only used to produce polyethylene and polyvinyl chloride films with smaller folding diameters.
Blown film is just one type of extrusion molding. The host and control system are the same as other extrusion processes. This section only introduces several key devices of the blown film auxiliary machine. www.handern.net Breathable film production line
2 blown film head
The blown film head is a key component to ensure the uniformity of film thickness and appearance quality. Its function is to form the molten material into a film tube with a certain shape, so that it can be blown and molded. The other is to generate a certain pressure to ensure the uniformity of the molten material. Squeeze out densely. The head is composed of a die and a connecting body.
(1) Die structure There are many types of die for blown film, such as "cross-head type" and spiral type with side-feeding core rod type and center-feeding type. At present, rotary die and lotus petal die are also developed. , Multi-layer complex regular die, etc. Except for some special products, the original mandrel and crosshead die have been replaced by spiral die. The lotus petal die is mostly used to produce wide-width polyethylene blown film. www.handern.net Breathable film production line
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