Self-reinforced polyolefin sheet preparation process
DATE：2019/8/23 9:09:05 / READ： / SOURCE：This station
Self-reinforced polyolefin sheet preparation process
(1) Temperature and pressure control. The extruder head is temperature-controlled by the silicone oil cycle. The PID proportional regulator and the transistor voltage regulator control the die temperature to an accuracy of 1 °C. The pressure and temperature in the machine head are indicated by the melt pressure and temperature sensor (P131-150MPa-990306E) and the supporting instrument.
(2) Low temperature extrusion process window probe. Experimental studies have found that HDPE and PP have an extrudable process window in a narrow temperature range slightly above the melting point (about 2 ° C above the melting point), and the extrusion resistance increases on both sides of the window, and the extrusion becomes It is difficult. Below this process window temperature, the material rapidly crystallizes rapidly in the squeezing die under extrusion high pressure, and the extrusion resistance is greatly increased, causing the extrusion to be interrupted; when the extrusion die temperature exceeds the process window temperature, the extrusion resistance increases. Extrusion will be unstable, and the discharge speed of the die will be uneven. If the temperature exceeds 5 °C of the process window, the elastic spray phenomenon will occur, and the extrudate will be severely twisted, which is easy to break during traction. Extrusion has the following characteristics in the process window temperature range:
1 The discharge rate along the section is uniform, and the extruded sheet has almost no die-expansion phenomenon, and the sheet thickness is uniform;
2 The product is completely transparent due to grain refinement, which is obviously different from the conventional extruded white opaque products.
3 The extrusion pressure is small, generally below 50MPa.
This is because the transient mesophase-high-pressure hexagonal phase is formed in the die, which has high fluidity and good lubrication for material extrusion, which not only reduces the extrusion pressure, but also makes The melt in the die changes from a viscous flow to a plunger flow, and the die-expansion phenomenon no longer occurs.
(1) Temperature and pressure control. The extruder head is temperature-controlled by the silicone oil cycle. The PID proportional regulator and the transistor voltage regulator control the die temperature to an accuracy of 1 °C. The pressure and temperature in the machine head are indicated by the melt pressure and temperature sensor (P131-150MPa-990306E) and the supporting instrument.
(2) Low temperature extrusion process window probe. Experimental studies have found that HDPE and PP have an extrudable process window in a narrow temperature range slightly above the melting point (about 2 ° C above the melting point), and the extrusion resistance increases on both sides of the window, and the extrusion becomes It is difficult. Below this process window temperature, the material rapidly crystallizes rapidly in the squeezing die under extrusion high pressure, and the extrusion resistance is greatly increased, causing the extrusion to be interrupted; when the extrusion die temperature exceeds the process window temperature, the extrusion resistance increases. Extrusion will be unstable, and the discharge speed of the die will be uneven. If the temperature exceeds 5 °C of the process window, the elastic spray phenomenon will occur, and the extrudate will be severely twisted, which is easy to break during traction. Extrusion has the following characteristics in the process window temperature range:
1 The discharge rate along the section is uniform, and the extruded sheet has almost no die-expansion phenomenon, and the sheet thickness is uniform;
2 The product is completely transparent due to grain refinement, which is obviously different from the conventional extruded white opaque products.
3 The extrusion pressure is small, generally below 50MPa.
This is because the transient mesophase-high-pressure hexagonal phase is formed in the die, which has high fluidity and good lubrication for material extrusion, which not only reduces the extrusion pressure, but also makes The melt in the die changes from a viscous flow to a plunger flow, and the die-expansion phenomenon no longer occurs.
Author：admin