Trimethyl-Dihydroquinolines (TMQs) function as primary antioxidants and are widely used in rubber compounds based on highly unsaturated rubbers to protect the rubber articles from oxidative degradation at ambient as well as higher temperatures. TMQs represent a group of antioxidants based on polymerized Aniline-Acetone condensation products. The individual products differ by the degree of polymerization and the Dimer, Trimer & Tetramer contents. Thus the composition, molecular weight distribution and performance as antioxidant of TMQ vary from supplier to supplier.
Pilnox TDQ-HP is a specially purified grade of TMQ antioxidant which is almost free from the objectionable impurities such as monomer and primary amine terminated impurities and has been developed for use in specialty applications requiring trouble-free continuous processing & product fabricating operations and high product service performance.
It is well known that only the secondary aminic groups ( = N–H ) function as antioxidants by the formation of nitroxyl radical ( - NO ) and thus only the Dimer, Trimer & Higher oligomers in TMQ act as effective antioxidants for rubbers. The primary aminic groups (- NH2 ) do not function as antioxidants. The primary amine impurities in TMQ antioxidant, such as; 2,2-bis(4’-amino-phenyl) propane (bis-aniline A), 3-(4’-aminophenyl) terminated TMQ, 6-(4’-aminophenyl) terminated TMQ also differ considerably from supplier to supplier.
The primary aminic groups are responsible for:
- Bluish colored blooming on uncured stock , activation of sulphur cross linking and thus initiating scorch,
- Destabilization of Insoluble Sulphur by decreasing its transition temperature to soluble Sulphur and thus causing scorch & sulphur bloom problems resulting in the loss of surface tack of the uncured rubber compounds.
- Dramatically decreasing the ‘peptization’ activity of NR based compounds. This results in the increased stock viscosity at processing temperatures which causes increase in the processing temperature, scorching, porosity, loss of surface tack etc.
High proportions of monomer content in TMQ antioxidant is also considered as an objectionable impurity since it is leached out in water and can cause porosity in thicker cross section extrudates.
Pilnox TDQ-HP is widely used in the manufacture of Truck & Bus Radials, Passenger Radials, OTR tyres, Steel cord conveyor belts and other technically sophisticated rubber products.
TYPICAL DOSAGES of PILnox TDQ-HP:
Please refer to the table for Pilnox TDQ.