Anti-Blocking Agents for Polyolefin Film Extrusion

Blocking is the adhesion of film layers to each other when wound into rolls or stacked in sheets. Anti-blocking agents prevent blocking by creating micro-roughness on the film surface.

Inorganic Anti-Blocking Agents

Silica (amorphous SiO2):

• Average particle size: 2–8 µm
• Refractive index close to polyolefins → minimal haze impact
• Best for optical films where clarity is critical
• Typical loading: 0.1–0.3% in LDPE/LLDPE

Talc (Mg3Si4O10(OH)2):

• Platelet structure creates surface roughness efficiently
• Lower cost than silica; slightly higher haze
• Typical loading: 0.3–0.5%

Organic Anti-Blocking Agents

Erucamide and oleamide (fatty acid amides) migrate to the film surface and create a low-friction layer. Reduce COF from >0.5 to <0.2.

Combined Slip/Anti-Block Systems

Optimal: 0.1–0.2% synthetic silica + 0.05–0.1% erucamide → minimizes blocking while maintaining COF <0.3 and haze <5%.

HMEChem supplies silica-based anti-blocking masterbatches and fatty acid amide slip agents for polyolefin film applications.