Degradation of polypropylene with hydroxylamine ester compositions
The invention relates to novel composition comprising hydroxylamine esters and thio compounds, which are suitable for lowering the molecular weight of polypropylene, propylene copolymers or polypropylene blends and result in an excellent degradation performance at temperatures below 220° C.
1. A polymer composition comprising
a) at least one hydroxylamine ester of formula (IC)
wherein
R a is acyl,
R 1 ′, R 2 ′and R 3 ′ are each, independently of one another, hydrogen or methyl,
n is 1 or 2,
when n =1, G 3 is C 2 -C 10 alkylene, C 2 -C 8 hydroxyalkylene or C 4 -C 32 acyloxy-C 2 -C 10 alkylene or C 4 -C 32 acyloxy-C 1 -C 4 alkyl-C 2 -C 10 alkylene and
when n =2 G 3 is (—CH 2 ) 2 C(CH 2 —) 2 ;
b) at least one sulphur compound of formula R 1 —S—H or of formula
wherein R 1 is C 8 -C 18 alkyl and B + is an alkali metal cation, an ammonium ion or a cholinyl cation and
c) polypropylene, propylene copolymers or polypropylene blends.
2. A polymer composition according to claim 1 wherein the at least one hydroxylamine ester of formula (IC) is of formula
3. A polymer composition according to claim 1 comprising
a) at least one hydroxylamine ester of formula
b) at least a mercaptane of formula R 1 —S—H and
c) polypropylene, propylene copolymers or polypropylene blends.
4. A polymer composition according to claim 1 comprising
a) at least one hydroxylamine ester of formula
b) at least one S-alkylthiosulphate of formula
and
c) Polypropylene, propylene copolymers or polypropylene blends.
5. A process for reducing the molecular weight of polypropylene, propylene copolymers or polypropylene blends, wherein a composition comprising components a) and b) according to claim 1 is added to the polypropylene, propylene copolymers or polypropylene blend to be degraded and the mixture is heated.
6. A process according to claim 5 , wherein a temperature range lower than 280° C. is employed.
7. A process according to claim 5 , wherein the composition is added to a blend of polypropylene with polyethylene selected from the group consisting of high density polyethylene (HDPE), high molecular weight high density polyethylene (HMW HDPE), ultra high molecular weight high density polyethylene (UHMW HDPE), medium density polyethylene (MDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), branched low density polyethylene (BLDPE) and ethylene-propylene-diene terpolymers (EPDM) containing small proportions of diene.