Before we delve into the selection criteria, we first need to understand the types of PE wax and its role in masterbatch.
Types of PE Wax and Their Applications. The market offers various types of PE wax. Understanding their characteristics is fundamental to making the right choice:
- Low-Molecular-Weight Polyethylene Wax (LDPE/HDPE Wax):
- Characteristics: Excellent lubricity and dispersibility; effectively reduces melt viscosity.
- Applications: Widely used in polyolefin (PE, PP) based masterbatches, especially for products with high dispersion requirements like films and fibers. HDPE wax generally has a higher melting point and hardness than LDPE wax.
- Oxidized Polyethylene Wax (OPE Wax):
- Characteristics: Contains polar groups like carboxyl and hydroxyl on its molecular chain, providing better compatibility with polar resins and inorganic pigments. It offers excellent wetting and dispersion properties.
- Applications: Ideal for masterbatches based on polar plastics such as PVC, PET, and ABS, as well as for filled masterbatches containing a high concentration of inorganic pigments (e.g., titanium dioxide, calcium carbonate).
- Polymerized PE Wax:
- Characteristics: Synthesized directly through polymerization, resulting in a narrow molecular weight distribution and good thermal stability.
- Applications: Suitable for applications with high requirements for thermal stability and low volatility, such as masterbatches for high-temperature engineering plastics.
- Pyrolysis PE Wax (Cracked PE Wax):
- Characteristics: Produced by the thermal cracking of high-molecular-weight polyethylene. It is relatively low-cost but has a broader molecular weight distribution and may contain low-molecular-weight oligomers.
- Applications: Suitable for general-purpose masterbatches. Use with caution in high-end applications to avoid issues like surface blooming caused by the migration of low-oligomer content.
How to Select PE Wax Based on Specific Applications
- Based on the Carrier Resin:
- Polyolefin (PE, PP) Masterbatch: Prioritize non-polar, low-molecular-weight PE wax.
- Polar Plastic (PVC, PET, ABS) Masterbatch: Choose a polar Oxidized Polyethylene Wax (OPE Wax) to enhance compatibility and dispersion.
- Based on the Pigment Type:
- Organic Pigments: Generally easier to disperse; a general-purpose PE wax is often sufficient.
- Inorganic Pigments (e.g., Titanium Dioxide, Carbon Black): These have a large surface area and are difficult to disperse. A low-viscosity or oxidized PE wax with superior wetting and dispersing capabilities is recommended. For high-concentration carbon black masterbatch, the right PE wax can significantly improve blackness and gloss.
- Based on the Final Product Requirements:
- Films and Fibers: Require exceptional dispersion. Select a low-molecular-weight PE wax with excellent dispersibility to avoid “gel” or “fisheye” defects.
- Injection Molded and Extruded Products: In addition to dispersion, consider the wax’s effect on surface gloss and mold release. A medium-to-high density PE wax may be suitable.
- Food Contact Applications: You must select a food-grade PE wax that complies with relevant regulations (e.g., FDA).
Conclusion
In summary, selecting the right PE wax is a decision-making process that requires balancing multiple factors.
Manufacturers should have a thorough understanding of their product’s formulation, processing technology, and end-use requirements. It is crucial to consult the technical data provided by wax suppliers and conduct lab-scale or pilot tests to verify the performance of the chosen PE wax.
A wise selection not only elevates the quality of the color masterbatch but also provides a competitive edge. While high-quality PE wax may have a slightly higher initial cost, the resulting improvements in production efficiency, reduction in defect rates, and enhancement of final product performance will deliver greater long-term economic benefits.
If you have some confusion for PE wax selection for your masterbatch, contact us without any hesitation and we’d love to offer some help.