Material Analysis
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Insufficient long-term heat aging performance of soft products
Problembeschreibung
PVC soft cable compounds using calcium-zinc stabilizers, after 168 hours of testing in a 100°C heat aging oven, have an elongation at break retention rate below 70% (standard requirement ≥80%), and cracks and discoloration appear on the product surface.
Ursachenanalyse
The long-term thermal stabilization effect of calcium-zinc stabilizers depends on the continuous consumption-regeneration cycle of metal soaps; in soft products, the plasticizers DOP/DINP migrate and carry away part of the stabilizer components; after ZnCl₂ accumulates to a critical concentration, it catalyzes and accelerates degradation (zinc burning effect); the antioxidant 1010/168 combination is insufficient.
Lösung
Increase the calcium-zinc stabilizer dosage to 3-5 phr (rigid products usually 2-3 phr); incorporate auxiliary stabilizers with longer molecular chains (pentaerythritol esters) to slow ZnCl₂ migration; add 0.3-0.5 phr antioxidant 1010+168 (1:2 ratio); select high molecular weight plasticizers to reduce migration; introduce hydrotalcite LDH to improve long-term stability.
Wichtigste Erkenntnis
The long-term heat aging performance of soft products depends on the stabilizer system design; the synergistic use of hydrotalcite and antioxidants is a key strategy for improving long-term stability.
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