Synthesis of Novel Hindered Amine Light Stabilizers (HALS) and Their Copolymerization with Ethylene or Propylene over Both Soluble and Supported Metallocene Catalyst Systems

Abstract

Novel polymerizable hindered amine light stabilizers (HALS) such 1-(but-3-enyl)-2,2,6,6tetramethylpiperidine (1), 1-(undec-10-enyl)-2,2,6,6-tetramethylpiperidine (2), 4-(but-3-enyl)-1,2,2,6,6pentamethyl-3,4-dehydropiperidine (3), 2-(but-3-enyl)-2,6,6-trimethylpiperidine (4), 4-(but-3-enyl)-1,2,2,6,6pentamethyl-4-piperidyl ether (5), 4-(undec-10-enylamide)-1,2,2,6,6-pentamethylpiperidine (6), 4-((N-nbutyl)-undec-10-enylamide)-1,2,2,6,6-pentamethylpiperidine (7), and bis(N-n-butyl-N-2,2,6,6-tetramethylpiperidine)-N-n-butyl-N-allyltriazine (8) were synthesized. All the aforementioned HALS monomers except for 5 and 8 were successfully copolymerized in fair to high yields with ethylene or propylene over eight different group 4 metallocene catalysts using methylalumoxane (MAO) as cocatalyst. Copolymerizations were also performed over a supported metallocene/SiO 2/MAO/triisobutylaluminum(TIBA) catalyst system. The silica-supported metallocene catalyst system readily promoted copolymerization of the sterically hindered monomer 2 with ethylene, however, copolymerizations using either 6 or 7 as comonomer failed. Moreover, a catalyst derived from the reaction of rac-[dimethylsilylenebis(1-indenyl)]zirconium dichloride (CA1) with triethylaluminum and trityl tetra(perfluorophenyl)borate (TRI-FABA) afforded HALS copolymers in high yields. Surprisingly, it was found that TRI-FABA, a strong Lewis acid, could impede the Lewis base activity of HALS monomers such as 2, 6 and 7 provided a sufficient relative amount of TRI-FABA was employed. Thus, once an equilibrium concentration between TRI-FABA and HALS monomer was established, the presence of HALS monomer no longer affected the rate of polymerization. Normally, metallocene catalysts are severely poisoned when traces of polar monomers (Lewis bases) are present, due to the Lewis acidic nature of the catalyst. Furthermore, a series of standard ethylene homopolymerizations over rac- [dimethylsilylenebis(4,5,6,7-tetrahydro-1-indenyl)]zirconium dichloride (CA2)/MAO catalyst system was performed in the presence of different sterically hindered amine model compounds such as 1-(1-methylene-2,6-di-tert-butylphenol)-2,2,6,6-tetramethylpiperidine (A),

Developing Polypropylene Bonded Hindered Phenol Antioxidants for Expanding Polypropylene Applications in High Temperature Conditions

“…There have been some research efforts to develop polymer-bonded antioxidants that offer reduced volatility to improve the long-term stability of polymer products [8][9][10][11]. This approach is particularly acute in thin film and coating applications.…”

Synthesis and photostabilizing performance of a polymeric HALS based on 1,2,2,6,6-pentamethylpiperidine and vinyl acetate

“…The synthesis of HALS of higher molecular weight by addition or condensation copolymerizations [9][10][11] or the grafting of photostabilizers onto the preformed polymer [12][13][14][15][16] are usual strategies described by the literature to eliminate or minimize such undesirable effects. The preparation of polymeric HALS by the copolymerization of hindered amines with ethylene or propylene is also an alternative route to reduce their physical loss [17,18] . Auer et al [19] described a novel and facile one-step synthetic route to prepare a HALS and its copolymerization with ethylene using a metallocene/methylalumoxane (MAO) as a catalyst system.…”

Synthesis and Light-Stabilizing Ability of a Series of Hindered Piperidine Derivatives

“…In the past two decades, several HALSs containing 2,2,6,6-tetramethylpiperidine have been reported, such as polymeric HALS, [1][2][3][4][5][6][7][8][9][10][11] multifunctional HALS [11][12][13] and reactive HALS. [4] Chimassorb 944, as an excellent representative of polymer HALS, with a number average molecular weight of about 2000 to 3000, exhibited good thermal stability and resistance to extraction.…”