Composite sheet extrusion process

日期:2019/5/30 8:12:17 / 阅读: / 来源:本站

Composite sheet extrusion process
(1) Sheet extrusion process. On-line composite sheet extrusion was carried out in Jiangsu Integrated Decoration Materials Co., Ltd. The three-layer co-extrusion composite sheet production line of Unin, Italy. The diameter of the main screw is 120mm, and the diameters of the two lateral screws are 70m and 45mm respectively. The lip of the T-shaped head is controlled by a microcomputer with an accuracy of 0.1m. The extrusion temperature is controlled by 24 points, wherein the main screw barrel temperature control is 16 segments, and the T-shaped machine head is 8 segments. The feed end starts at 190 ° C, the temperature in the middle zone is 22 ° C, the inlet end of the T-shaped head is 205 ° C, and the outlet end of the lip is 195 ° C. The lip gap was 2.3 mm and the distance from the pressure roller was 20 cm. After the plate comes out of the die lip, it directly enters the lower roller, and enters the pallet line from the upper roller through the intermediate roller. The three rolls are 90 ° C for the lower roll and 80 ° C for the middle roll.
70 ° C. The PU nonwoven fabric sheet is preset on the lower side of the first pressure roller near the lip side. After the substrate extrusion process is smooth, the three-roller pitch is appropriately adjusted, and the sheet is fed into the first press roll from the lower side of the extrudate to obtain a qualified composite sheet.
(2) The main factors affecting the quality of composite sheets.
1 extrudate melt temperature. The temperature difference between the melt melted into the cold press roll is large, and the flow orientation and internal stress are easy to occur. Especially when the die lip size is not well matched with the gap between the three rolls, the plate will have a large flow orientation. Anisotropy. It is therefore important to control the melt temperature of the extrudate. In principle, in the case of extrusion of composite sheets, the melt temperature of the extrudate is reduced as much as possible. For PP and its multiphase blend systems, the melt temperature is preferably controlled between 190 ° C and 195 ° C.
2 three-roll gap and temperature control. An example is a device in which an extrudate is fed from a lower roll to a roll. The gap between the lower roll and the middle roll of the extrudate is mainly used to control the balance of the extrusion amount, and the gap between the middle roll and the upper roll is mainly used for controlling the size of the plate, and at the same time, the function of glazing and printing pattern can be provided according to requirements. Usually the gap between the middle and upper rolls is smaller than the gap between the lower and middle rolls due to the cooling shrinkage of the polymer material, as well as the functional requirements of the glazing and printed patterns. The temperature control between the three rolls is very important, and the temperature of the three rolls is sequentially decreased. However, if the temperature of the rolls is too low, a large internal stress will be generated, resulting in a bow shape, which affects the subsequent processing and application of the sheet.

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