Published: November 1983
This report focuses on stabilization additives for the plastics industry, the faster growing sector, with polyolefins accounting for the largest consumption. The hindered phenols are the principal primary antioxidants used in plastics, with the phosphites and thioesters supplementing these in synergistic combinations as secondary antioxidants. Among the hindered phenols we have examined two. The largest volume hindered phenol is butylated hydroxytoluene (BHT), often described as the workhorse of the antioxldants. For the second hindered phenol, we chose one of the commercially dominant high molecular weight, high performance antioxldants. It is marketed by Ciba-Geigy as Irganox@ 1010.
We also updated the evaluations for the two leading compounds in use as secondary antioxidants--dllauryl thiodipropionate (DLTDP) and tris(nonylpheny1) phosphite (TNPP). The former compound was examined in the earlier PEP report on antioxidants, and the latter in PEP Report No. 110, "Organic Phosphorus Compounds" (April 1977). In the stabilization of plastics, antioxidants (primary and secondary) are commonly used in conjunction with light stabilizers. The recently introduced (1975) hindered amine light stabilizers (HALS) are the fastest growing. The major growth in the use of HALS has been at the expense of the conventional benzophenones and benzotriazoles. We have included the economic evaluation of one of these currently topical HALS compounds (Ciba-Geigy's Tinuvin@ 770).
The report also contains a brief technical review of the principles underlying thermal and light degradation and methods of stabilization, and a survey of the industry status.