Aluminum foil composite production line with enhanced POM Technology
DATE：2021/7/14 8:33:14 / READ： / SOURCE：This station
Aluminum foil composite production line with enhanced POM Technology
Mixing temperature; Because POM is easy to decompose at high temperature, the temperature setting of screw extruder is an important factor affecting the product quality. When the preparation temperature is low, the wrapping effect of glass fiber is poor, resulting in the exposure of glass fiber; If the temperature is too high, POM will decompose. Therefore, the setting of melting mixing temperature should be based on the principle that POM does not decompose and should be controlled close to the melting point. The preparation temperature of typical glass fiber reinforced POM is controlled as follows:The temperature settings of the first, second, third, fourth, fifth and die are 170 ℃, 180 ℃, 190 ℃, 195 ℃, 190 ℃ and 185 ℃ respectively. Aluminum foil composite production line www.handern.com
Screw combination and screw speed; For the extrusion granulation of easily decomposable polymer, the principle of screw combination is to ensure a certain shear effect and mixing effect, and at the same time avoid local overheating. Especially for the extrusion granulation of glass fiber reinforced POM, the friction between glass fiber and screw, glass fiber and barrel will produce a lot of heat. In order to avoid POM decomposition caused by local high temperature of screw, the screw elements should be combined in multiple sections according to the principle of dispersive combination and uniform shear, so as to reduce the retention time from small friction objects to the left. The thermal oxidative cracking of POM was avoided. In general, the combination of screw elements with medium shear effect is better. If the shear action is too strong, a large amount of shear heat will be generated, which will decompose POM. At the same time, the glass fiber will be cut too short, which will lose the best reinforcement effect in POM resin matrix; At the same time, if the glass fiber is too long, the interface between the glass fiber and POM resin matrix is obvious, the interfacial adhesion is weak, and the strength of the product decreases. Aluminum foil composite production line www.handern.com
Screw speed; Increase the speed, increase the screw shear, improve the mixing effect; On the other hand, increasing the screw speed can reduce the residence time of materials; However, the screw speed should not be too high, otherwise, the screw temperature may rise due to the increase of friction heat, resulting in the decomposition of POM. Therefore, the screw speed setting principle is to ensure that POM plasticization is complete under the condition of appropriate increase of screw speed, which is conducive to ensuring product quality. At the same time, there is a certain correlation between screw speed and screw length diameter ratio. If the length diameter ratio of screw is large, the screw speed can be increased appropriately; If the screw length diameter ratio is small, the screw speed should not be too high, otherwise it is easy to cause uneven mixing of glass fiber, especially poor distribution mixing effect. At present, the rotational speed of domestic twin-screw extruder can reach more than 400 R / min; The speed of imported twin-screw extruder (such as German WP) can reach more than 700R / min. The daily production twin-screw extruder is usually used. When the length diameter ratio of the screw is 32:1, the screw speed can be set at 350r / min. at this time, the feeding speed should be moderate to ensure that the material in the barrel is in a semi starvation state. Aluminum foil composite production line www.handern.com
Drying and cooling; When preparing glass fiber reinforced POM, attention must be paid to drying. One is the drying of raw resin POM. As POM is a hygroscopic resin, it is easy to absorb water, and at high temperature in the screw, POM is easy to be degraded by water, so POM must be dried fully before processing. Blower dryer, vacuum dryer and dehumidification dryer can be used for drying. Blower dryer is commonly used in factories. The drying conditions are as follows: temperature 70 ~ 80 ℃, time about 4h, material layer thickness < 30mm, moisture content below 0.05%. Second, the glass fiber should also be dried, because the moisture in the glass fiber is also large. The drying conditions of glass fiber are: temperature 120 ℃, time 4H. Because a large number of dryers are used in the preparation process of glass fiber reinforced POM, the balance between drying quality and output and the matching problem with the output of twin-screw extruder should be considered in production. Many dryers can be purchased to meet the requirements of drying quality and output. It is not allowed to carry out twin-screw granulation without thorough drying, which will lead to the decline of the performance of glass fiber reinforced POM materials and greatly increase the probability of waste products.
As the hardness of glass fiber reinforced POM is high, the properties are brittle, and it is not easy to cut grains. The cutter of the granulator is seriously worn, and the cutter price is high, which increases the cost of reinforced POM. In order to reduce the wear of the cutter and make the cut particles uniform and beautiful, the water tank with higher temperature can be used for cooling. In this way, the cut particles have less burr and are beautiful and round, which also reduces the wear of the cutter and enhances the powder debris loss of POM. Aluminum foil composite production line www.handern.com
As mentioned above, the preparation process of glass fiber reinforced POM greatly affects the performance, normal production and cost of reinforced POM, so in practice, the process conditions should be strictly controlled, and the best process parameters should be selected according to the equipment conditions. Aluminum foil composite production line www.handern.com
Author：admin