DEVELOPMENT OF STABILIZERS FOR POLYMER

Abstract

Three new monomeric antioxidants containing hindered phenol, six new monomeric light stabilizers containing hindered amine or ortho-hydroxy benzophenone and six light and thermal bifunctional stabilizers were synthesized and studied. The three new monomeric antioxidants are 3,5-di-tert-butyl-4-hydroxy benzyl, (4- methacryloyl amino) tolyl carbamate-2 (M1); 3,5-di-tert-butyl-4-hydroxy benzyl, (6- methacryloyl amino) hexyl carbamate-1 (M2) and 3,5-di-tert-butyl-4-hydroxy benzyl, (6-acryloyl amino) hexyl carbamate-1 (M3) (Appendix B). A new idea of a two-step controlled isocyanation was applied to synthesize M1, M2 and M3. In the first step methacrylic acid (MAA) or acrylic acid (AA) reacts with toluene 2,4-diisocyanate (TDI) or hexamethylene diisocyanate (HMDI) in mole ratio of 1 to 1 at 60°C. In the second step, the products from the previous step, used as an intermediate, was directly added to 2,6-di-tert-butyl-4-hydroxy methyl phenol (DBHMP) in 1 to 1 mole ratio at a given temperature in the presence of a catalyst dibutyltin dilaurate (DBTDL). They were characterized by IR, NMR and Elemental Analyses. Test results show that these new monomeric antioxidants possess stabilization capability for protecting polypropylene (PP) film against thermal oxidation and that they are copolymerizable with vinyl monomers. The six new monomeric light stabilizers are 2,2,6,6-tetramethyl-4-piperidinyl, ( 4- methacryloyl amino) tolyl carbamate-2 (M4); 2,2,6,6-tetramethyl-4-piperidinyl, (4- acryloyl amino) tolyl carbamate-2 (MS); 2,2,6,6-tetramethyl-4-piperidinyl, (6- methacryloyl amino) hexyl carbamate-1 (M6); 2-hydroxy-4-benzophenonyl, (6- methacryloyl amino) hexyl carbamate-1 (M7); 2,2,6,6-tetramethyl-4-piperidinyl, (6- acryloyl amino) hexyl carbamate-1 (M8) and 2-hydroxy-4-benzophenonyl, (6-acryloyl amino) hexyl carbamate-1 (M9) (Appendix C). They were also synthesized by the twostep controlled isocyanation. They were characterized by IR, NMR, UV and elemental analysis. Experimental results show that these new monomeric light stabilizers possess stabilizing ability for protecting polypropylene (PP) against photo-oxidation and that they can homopolymerize and copolymerize with vinyl monomers. The six new bifunctional stabilizers are 2-hydroxy-4-benzophenonyl, 2,2,6,6- tetramethyl-4-piperidinyl hexamethylene dicarbamate S1, (MW=540); 2-hydroxy-4- benzophenonyl, 3,5-di-tert-butyl-4-hydroxyl benzyl hexamethylene dicarbamate S2, (MW=619); 3,5-di-tert-butyl-4-hydroxyl benzyl, 2,2,6,6-tetramethyl-4-piperidinyl hexamethylene dicarbamate S3, (MW=562); 2,2,6,6-tetramethyl-4-piperidinyl, 2- hydroxy-4-benzophenonyl toluene 2,4-dicarbamate S4, (MW=546); 3,5-di-tert-butyl-4-hydroxyl benzyl, 2-hydroxy-4-benzophenonyl toluene 2,4-dicarbamate SS, (MW=625) and 3,5-di-tert-butyl-4-hydroxyl benzyl, 2,2,6,6-tetramethyl-4-piperidinyl toluene 2,4-dicarbamate S6, (MW=568) (Appendix D). Again two-step controlled isocyanation was applied. In the first step a compound containing a stabilizing functional group, 2,4-dihydroxy benzophenone (DHBP) or 2,2,6,6-tetramethyl-4- piperidinol (TMP), reacts with TDI or HMDI at a mole ratio of 1 to 1 to form an intermediates. In the second steps was directly added to another compound containing a different stabilizing functional group such as TMP or DBHMP at a 1 to 1 mole ratio at 22°C or 80°C in the presence of DBTDL catalyst. Their structures were characterized by IR, 1H-NMR, UV and elemental analysis. Experimental results show that these new bifunctional stabilizers are effective in protecting PP against photo-oxidation and thermal-oxidation. The effectiveness of these stabilizers in relation to their structures is discussed.