Overview
PVC foam boards are widely used in industries such as construction, advertising, furniture, and interior decoration due to their lightweight structure, durability, moisture resistance, and good insulation properties.
The performance of PVC foam boards depends largely on the formulation of PVC resin and additives used during the extrusion process. A typical formulation includes stabilizers, foaming agents, lubricants, fillers, and processing aids to ensure uniform foaming structure, good mechanical strength, and stable processing performance.
Key Raw Materials Used in PVC Foam Board Production
1. PVC Resin
The base material for PVC foam boards is PVC suspension resin, commonly including:
- SG-7 (K value around 60)
- SG-5 blended with SG-8
These resins provide the required balance of plasticization performance, melt strength, and mechanical properties for foaming processes.
2. PVC Stabilizer
Common stabilizer systems include:
- Lead-based one-pack PVC stabilizers
- Calcium-zinc (Ca/Zn) stabilizers
Function
Stabilizers protect PVC from thermal decomposition during processing, preventing degradation and discoloration while helping the material maintain stable melt properties during extrusion.
3. Chemical Foaming Agents
Foaming agents create the cellular structure inside PVC foam boards.
Common foaming agents include:
- AC blowing agent (Azodicarbonamide) – an exothermic foaming agent
- NC blowing agent (white foaming agent) – an endothermic foaming agent
These agents decompose under heat to release gases that form uniform bubbles within the PVC matrix.
4. PVC Foaming Regulator
Foaming regulators play an important role in controlling the structure of foam products.
Function
- Improve melt strength during extrusion
- Prevent bubble coalescence or collapse
- Ensure uniform and stable foam cell structure
They also promote PVC plasticization, ensuring good melt flow during processing.
5. Processing Aid (ACR-175)
Processing aids such as ACR-175 improve the overall processing behavior of PVC.
Function
- Promote plasticization of PVC resin
- Improve material flow and melt strength
- Reduce adhesion between materials and metal surfaces during processing
This helps achieve stable extrusion and better product surface quality.
6. Internal Lubricant – G60
G60 lubricant acts as an internal lubricant in the PVC formulation.
Function
- Promote plasticization of PVC resin
- Improve polymer melt fluidity
- Enhance surface finish of finished foam boards
7. External Lubricant – PE Wax
Polyethylene (PE) wax functions as an external lubricant.
Function
- Reduce friction between the PVC melt and machine surfaces
- Prevent material from sticking to processing equipment
- Improve extrusion stability
8. High-Melting Lubricant (AC-316A or OA-6)
These high-melting-point oxidized polyethylene waxes provide additional lubrication during later stages of processing.
Function
- Provide both internal and external lubrication
- Improve processing stability during middle and late extrusion stages
9. Pigments and Optical Additives
To improve the appearance and brightness of PVC foam boards, pigments are added, including:
- Titanium dioxide (TiO₂) – provides whiteness and UV resistance
- Optical brighteners – enhance brightness
- Ultramarine blue pigment – corrects yellow tint and provides a blue-white appearance
These additives improve the visual quality and color consistency of foam boards.
10. Fillers
Coated calcium carbonate (CaCO₃) is commonly used as a filler.
Function
- Increase the mechanical strength of foam boards
- Improve dimensional stability
- Reduce production cost
Proper filler levels help maintain good foaming structure while enhancing product durability.
Conclusion
A well-balanced formulation of PVC resin and additives is essential for producing high-quality PVC foam boards. Each component in the formulation contributes to specific properties such as:
- Stable foaming structure
- Good mechanical strength
- Smooth surface finish
- Efficient processing performance
By optimizing the combination of resins, stabilizers, foaming agents, lubricants, and fillers, manufacturers can produce PVC foam boards that meet the performance requirements of various industrial applications.
