Durastream CPVC vs. PVC Processing

Can We Use a PVC Machine for CPVC Production?

The CPVC process using extrusion and injection is very similar to the PVC process.

PVC equipment and tools can typically be used in the CPVC manufacturing process. However, proper temperature settings, screws, and molding tools will be necessary.

What Is the Main Difference Between CPVC and PVC Processing?

The main difference between PVC and CPVC processing is in thermal stability and viscosity.

If moderate temperatures and heat are not applied to CPVC, CPVC will not melt and physical properties will not be performed well. Hydrochloric acid decomposes when exposed to high temperatures. The crystalline melting points for PVC and CPVC are pictured below.

This is not guaranteed - for reference purposes only.

Can We Use a PVC Machine for CPVC Production?

Key Points

PVC and CPVC materials have different thermal stabilities.

  • CPVC materials need to reduce the residence time of the molding tools as much as possible.
  • Resin temperature settings are important to ensure the melting and gelation of the material.

Viscosity (Fluidity)

CPVC viscosity is generally higher than that of PVC. PVC viscosity can simply be read as K-Value=Polymerization. In the case of CPVC, viscosity (K-Value) is calculated by PVC polymerization degrees and chlorination degrees.

Key Points

  • Motor Load, Back Pressure
    If back pressure is high and it’s hard to increase production speed, the material will remain inside the die for longer and burn.
  • Screw/Mold Shape
    The structure of the screw and die tools is an important factor. The tools need to be matched with CPVC production.
  • Attention to Shear Heating
    The screw undergoes shear heating. Moderate heat is required to keep the plastic at the correct temperature.

Processing Differences: PVC vs CPVC

Extruder

PVC CPVC
Machine Screw Mortar:High Torque
Screw:Parallel φ60-170
      Conical φ50-85
Screw Mortar:High Torque
Screw:Parallel φ60-135
      Conical φ50-70
Condition Screw Rotation Lower than PVC
Barrel Temp. 300 – 340 ℉ 340 – 410 ℉/span>
Mold Type Stainless Steel Chrome Plate Stainless Steel Chrome Plate
Less volume (residence part)
Mold angle

*These reference values are not guaranteed.

Injection

PVC CPVC
Machine Screw Mortar: High Torque
Barrel Cooling: Blower
Screw Mortar: High Torque
Barrel Cooling: Blower
Barrel Zone: 4-5 Zone
Nozzle: Short Nozzle、φ:Larger than PVC
Condition Screw Rotation 9-14 m/sec 8-13 m/sec
(lower than PVC)
Barrel Temp. 320 – 365 ℉ 320 – 392 ℉
Holding Pressure 100 – 170 MPa 100 – 170 MPa
Mold Type Stainless Steel Chrome Plate
Runner: Thick
Hot Runner: No Need
Gate: Direct Gate
Wall Thickness > Gate Diameter
Stainless Steel Chrome Plate
Runner: Thick
Hot Runner: No Need
Gate: Direct Gate
Larger than PVC

*These reference values are not guaranteed.

Single Extrude (Profile)

PVC CPVC
Machine Single Screw Machine
Screw: Dulmate, Fullfight
Single Screw Machine
Screw: Recommend Fullfight (Dulmate)
L/D = 22 – 25
Compression Ratio: 2.5 – 3.2
Condition Screw Rotation 15~ rpm (65mm single) 15–25 rpm (65mm single)
Barrel Temp. 284 – 338 ℉ 300 – 370 ℉
Mold Type Stainless Steel Chrome Plate Stainless Steel Chrome Plate

*These reference values are not guaranteed.