Process of degradable plastic production equipmenProcess of degradable plastic production equipment:
(1) The temperature of each section on the barrel of the plastic sheet production equipment gradually rises from the feeding section to the junction of the barrel and the forming mold.
(2) The mold temperature of the degradable plastic production equipment is slightly higher than the barrel temperature, and the higher temperature is controlled at 5-10°C. The temperature at both ends of the mold is slightly higher than the temperature in the mold, and the higher temperature is controlled at 5-10°C.
(3) In the form of sheet feeding, the upper roller surface of the three-roller middle roller should be on the same level as the lower plane of the die lip; the lip end surface is parallel to the centerline of the middle roller, and the distance is 50-100 mm.
(4) The die gap should be slightly less than or equal to the thickness of the sheet product, and the die gap should be slightly less than the die gap on both sides.
(5) Note that the roughness r of the three-roller working surface of the degradable plastic production equipment should not be greater than zero. When cleaning the roller surface, do not scrape the roller surface with a hard steel knife, but use a copper knife to clean the residual material on the roller surface.
(6) The surface of the roller should have a certain medium height; the gap between the three rollers should be equal to or slightly larger than the thickness of the plate.
(7) The temperature control of the forming mold should be stable. When the temperature is high, the flow rate of the melt in the mold becomes faster. When the temperature is lower, the flow rate of the melt in the mold becomes slow, and the unstable melt flow rate will cause a large error in the longitudinal thickness of the plate (sheet) product.
(8) Pay attention to the degradable plastic production equipment to control the working surface temperature of the three rollers. The feed roller should be slightly higher and the discharge roller should be lower. If the temperature of the roller surface is too high, the slab is not easy to roll off, and the product surface is prone to horizontal stripes; the low temperature makes the surface of the product dull. According to this phenomenon, the roller surface temperature control should be adjusted in time.
(9) The three-roller running speed is slightly higher than the extruding speed of the slab from the die, and the speed difference is generally less than 10%. The working speed of the three-roller should be controlled stably, and the running speed is too fast or too slow to have a greater influence on the thickness error of the plate.
(10) When polyolefin plastic is extruded into plates (sheets), the screw adopts abrupt structure, the compression ratio is (3-4):1, the melt flow rate is: HDPE 0.3~2.0g/10min, LDPE 0.1~ 0.3g/1min, PP 0.5~1.5g/10min. For non-crystalline polymer resin extruded plates (sheets) such as ABS, progressive screws should be selected with a compression ratio of (1.6-2. 5):1.
(11) In the extrusion molding of plastic plates (sheets), except for PVC, polyethylene, and polypropylene resins that are generally not processed before extrusion, other plastics should be dried before extrusion. Otherwise, an exhaust extruder should be used for extrusion molding.