Thermally sensitive materials are generally classified […]
Thermally sensitive materials are generally classified into hard and soft, the difference being the amount of plasticizer added to the raw material, less than 10% being hard, and more than 30% being soft. PVC special injection molding machine screw
1. No obvious melting point, softening at 60 °C, viscoelastic state at 100 °C-150 °C, narrow melting temperature range at 140 °C, poor thermal stability, easy decomposition, rapid decomposition at 170 °C, softening point close to decomposition point, decomposition release For HC1 gas.
2. Due to the high viscosity of UPVC melt, poor thermal stability, temperature time will lead to decomposition, so it has a corrosive effect on general steel;
3. The temperature control is strict, the screw design should be as low as possible to prevent overheating, the flow channel must be smooth, there must be no dead angle, and the accumulation of material can be prevented from decomposing;
4. The screw barrel should be protected from corrosion;
5. The injection molding process needs to be strictly controlled. PVC special injection molding machine screw.
L/D=18-21, h3=0.067-0.08D, ε-1.6-2, L1=40-45%, L2=35-45%, in order to prevent the hiding of the material without apron, head 20 ° C -30 ° C, using a hard chrome plated screw;
The choice of temperature control:
melted cylinder multi-stage air cooling device;
low shear high mixing UPVC special screw barrel device PVC special injection molding machine screw.