Chemical Knowledge 05:Eco-friendly Calcium-zinc Stabilizers for PVC
Update time: 26-01-26 Views: 32
Eco-friendly Calcium-zinc Stabilizers for PVC
1. Background
The world's PVC heat stabilizers mainly include lead salts, calcium-zinc complexes, organotin, organoantimony, organic auxiliary heat stabilizers, and rare earth compounds. Traditional lead salt stabilizers and calcium-zinc composite stabilizers still dominate in production volume, and these two categories remain the primary stabilizers used in China. With the industry's lead-free development trend, calcium-zinc stabilizers have essentially become the direction for PVC stabilizer development in China.
2. What are the advantages of calcium-zinc stabilizers?
Environmentally friendly
Free of heavy metal elements (lead, cadmium) and compliant with the latest environmental standards worldwide (such as EU RoHS Directive, REACH Directive, etc.).
Resistance to sulfide contamination
In PVC door and window profiles, composite lead-based heat stabilizers used in some northern regions of China (where acid rain occurs due to extensive use of sulfur-containing coal) are prone to blackening, whereas calcium-zinc heat stabilizers are not subject to such contamination.
Excellent system switching characteristics
When transitioning from traditional composite lead heat stabilizers to organotin heat stabilizers, cross-contamination occurs, resulting in high system switching costs. Calcium-zinc heat stabilizers do not react with either of these two stabilizers, enabling low-cost mutual switching.
Low density allows for increased calcium carbonate content and cost reduction
Compared with composite lead heat stabilizers, calcium-zinc heat stabilizers have approximately 40% lower density. Simply switching the heat stabilizer in PVC products reduces the weight per meter by an average of about 2%.
3. What are the usage characteristics of calcium-zinc stabilizers?
Narrower processing window, requiring strict adherence to processing parameters
Compared with traditional composite lead heat stabilizers, calcium-zinc heat stabilizers have relatively inferior long-term thermal stability, are prone to yellowing during prolonged processing, and exhibit higher sensitivity to process temperatures.
Higher volatile content; formulation should incorporate high-melting-point, low-volatility lubricants
Compared with traditional composite lead heat stabilizers, calcium-zinc stabilizers contain higher levels of organic compounds, making them more prone to exudation. Lubricant selection requires careful consideration. Ester-based lubricants effectively balance flow and demolding properties during plastic processing, offer long production cycles, resist exudation, and can be widely used in calcium-zinc stabilizer formulations.
