Synonyms: Phosphonousacid, [1,1'-biphenyl]-4,4'-diylbis-, tetrakis[2,4-bis(1,1-dimethylethyl)phenyl]ester (9CI);4,4'-Biphenylenediphosphonous acidtetrakis(2,4-di-tert-butylphenyl) ester;Hostanox P-EPQ;Irgafos EPQ;IrgafosP-EPO;Irgafos P-EPQ-FD;Irgafos P-EPQFF;Irgafos PEPQ;Irganox P-EPQ;P-EPQ;Phos 2;Sandostab EPQ;Tetrakis(2,4-di-tert-butylphenyl)4,4'-biphenyldiphosphinate;Tetrakis(2,4-di-tert-butylphenyl)4,4'-biphenylenediphosphonite;Tetrakis(2,4-di-tert-butylphenyl)[1,1'-biphenyl]-4,4'-diylbisphosphonite;Tetrakis(2,4-di-tert-butylphenyl-4,4'-biphenylylene-diphosphonite);