Synthesis and properties of new polymerisable antioxidants

Abstract

Five new monomeric antioxidants containing hindered phenol have been synthesised by direct addition of 2,6-di-tert-butyl-4-hydroxy methyl phenol (DBHMP) to m-isopropenyl-α,α-dimethyl isocyanate (TMI) or allyl isocyanate (AI), and by controlled isocyanation in two steps, in which methacrylic acid (MAA) or acrylic acid (AA) reacts with toluene-2,4-diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) in 1 to 1 mole ratio at 60°C, and this product as an intermediate was directly added to DBHMP in 1 to 1 mole ratio in presence of a catalyst dibutyltin dilaurate (DBTDL). These new monomeric antioxidants are 3,3-di-tert-butyl-4-hydroxybenzyl, m-isopropenyl-α,α-dimethyl benzyl carbamate (A), 3,5-di-tert-4-hydroxy bezyl, allyl carbamate (B), 3,5-di-tert-butyl-4-hydroxy benzyl, (4-methacryloyl amino) tolyl carbamate-2 (C), 3,5-di-tert-butyl-4-hydroxy benzyl, (6-methacryloyl amino) hexyl carbamate-1 (D), and 3,5-di-tert-butyl-4-hydroxy benzyl, (6-acryloyl amino) hexyl carbamate-1 (E). They were characterized by IR, NMR and elemental analyses. Their stabilizing action for protecting polypropylene against thermal oxidation and their polymerizability were examined. Results show that these new monomeric antioxidants possess stabilising effect against thermal oxidation and they are capable of copolymerizing with vinyl monomers. © 1998 Elsevier Science Limited. All rights reserved.