Extrusion & Post
9 Aufrufe
Synergy of PPA with calcium-zinc stabilizers in PVC profiles
Problembeschreibung
When PPA is applied to a calcium-zinc stabilizer PVC profile system, competition between PPA and the lubricating components of the stabilizer occurs, resulting in insufficient initial lubrication, and the product shows initial scuffing.
Ursachenanalyse
The metal soaps and lubricants in the calcium-zinc stabilizer compete with the PPA fluoropolymer for the metal surfaces of the screw and die; the PPA coating is partially eluted or covered by the calcium-zinc lubricating components, affecting the PPA function; the three components (PPA/calcium-zinc lubrication/external lubrication) form a composite coating on the metal surface with a complex interface.
Lösung
Reduce the external lubricant by 0.1-0.2 phr to leave room for the PPA coating; first pre-treat the screw and die with PPA (blank run for 30 minutes to form a stable coating) and then add the calcium-zinc formulation; select a PPA grade certified as compatible with the calcium-zinc system; use a torque rheometer to verify the PPA/lubricant synergistic effect.
Wichtigste Erkenntnis
The application of PPA in calcium-zinc PVC systems requires special consideration of the competition from lubricating components, and pre-treating the die coating is a key step.
War das hilfreich?
0 Personen fanden dies hilfreich
Vielen Dank für Ihr Feedback!