New combined hindered phenol/hindered amine stabilizers for polymers based on diphenylmethane-4,4′-diisocyanate

A new type of combined stabilizer based on hindered phenols and Hindered Amine Stabilizers (HAS) were synthesized and tested as light stabilizers. 2,4-Di- tert-butylphenol ( I) and 2- tert-butyl-4-methylphenol ( II) were coupled with 4-hydroxy-2,2,6,6-tetramethylpiperidine (TMP), 4-hydroxy-1,2,2,6,6-pentamethylpiperidine (PMP), 4-amino-2,2,6,6-tetramethylpiperidine (ATP), 4- N-butyl-amino-2,2,6,6-tetramethylpiperidine (BATP) or 4-hydroxy-2,2,6,6-tetra-methyl-piperidin- N-oxyl ( N-oxyl) through the reaction with diphenylmethane-4,4′-diisocyanate. The structure and purity of the synthesized compounds were proved by conventional analytical methods. They were tested as light stabilizers in polypropylene films. Stabilizing efficiency depends on the structure of the phenol as well as on the structure of the HAS. Derivatives of phenol I exhibited better efficiency compared with phenol II for all HAS used. Concerning the structure of HAS stabilizing activity increased in the following order ATP