New phenylenediamine antiozonants for commodities based on natural and synthetic rubber

Abstract

For protection of elastomeric materials against ageing, antioxidants such as UV-stabilizers and antiozonants are used. Although historically N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD) was the only approved antiozonant in Germany, a range of other phenylene diamine antiozonants (excluding 6PPD) are permitted for use in rubber articles intended for repeat food-contact use in the US (FDA regulations chapter 21 Part 177.2600). The biggest disadvantage of 6PPD is its partial decomposition during the vulcanization leading to the formation of toxic primary aromatic amines (PAA), such as aniline and secondary aromatic amines (SAA). A number of new PPDs have been developed and patented, that due to their chemical structures, are far less soluble in aqueous solutions but a lot more soluble within the rubber matrix. They therefore show significantly less migration of PAA and SAA. These new antiozonants were investigated and compared to 6PPD using commercial rubber materials with a certain content of antiozonant with regard to their migration of PAA and SAA into three different food simulants. The lowest concentration of PAA and SAA in all food simulants was measured in the RU 997 stabilized elastomer. Due to this fact RU 997 was permitted as a new antiozonant for commodities based on rubber according to the Recommendation XXI 'Articles based on natural and synthetic rubber' of the Federal Institute for Risk Assessment (BfR). RU 997 therefore represents an alternative for 6PPD with less migration of aromatic amines.

Risk from exposure to arylamines from consumer products and hair dyes

“…Exposure of the general population to arylamines from rubber products can occur from the decomposition products of UV-stabilizers and antiozonants. For example, aniline and derivatives are formed and were found to migrate into food simulants (54). Multilayer films, which are extensively used by the food packaging industry, can contain primary aromatic amines (PAAs) and other contaminants.…”

The Tire Wear Compounds 6PPD-Quinone and 1,3-Diphenylguanidine in an Urban Watershed

“…It was recently reported by Tian et al ( 2021 ) that another tire additive, N-phenyl-N'-(1,3-dimethylbutyl)-p-phenylenediamine (6PPD) undergoes oxidation in the environment to form the by-product, 6PPD-quinone (6PPD-q). The 6PPD compound is used as an anti-oxidant in the production of synthetic rubber and it is present in tires in mass fractions ranging from 0.4 to 2% (Krüger et al 2005 ; Tian et al 2021 ). The oxidation by-product of 6PPD was identified as a likely candidate compound causing mass mortalities of coho salmon ( Oncorhynchus kisutch ) as they return to spawn in urban streams in the Pacific Northwest region of the USA (Tian et al 2021 ).…”

Research changes in the properties of butadiene-nitrile rubber under various aging conditions

“…And also widely used in the rubber industry amine antioxidant 6PPD-N-(1,3-dimethylbutyl)-N 0 -phenyl-pphenylenediamine (China). [13][14][15][16] The mixtures were prepared by mixing on rollers Cm350 150/150 (China) during 30 min. 11 Vulcanization of samples for research was carried out on a vulcanization press 100-400 2E (Russia) at a temperature of 155 � C. The optimal solidification time (t 90 ) was obtained from the curing characteristics using a Rubber Process Analyzer (RPA2000, Alpha Technologies).…”