Process for reducing the molecular weight of polypropylene

A process for reducing the molecular weight of polypropylene, propylene copolymers or polypropylene blends, said process comprising heating the polypropylene, propylene copolymers or polypropylene blends at a temperature between 160° C. and 280° C. in the presence of at least one hydroxylamine ester of the formula:

• Ra is an acyl radical selected from the group consisting of —C(═O)—H, —C(═O)—C1–C19alkyl, —C(═O)—C2–C19alkenyl, —C(═O)—C2–C4alkenyl-C6–C10aryl, —C(═O)—C6–C10aryl, —C(═O)—O—C1–C6alkyl, —C(═O)—O—C6–C10aryl, —C(═O)—NH—C1–C6alkyl, —C(═O)—NH—C6–C10aryl, —C(═O)—N(C1–C6alkyl)2, —P(═O)—C1–C19alkyl, —P(═O)2—C1–C19alkyl, —P(═O)—C6–C10aryl, —P═O(—C1–C19alkyl)2, —P═O(—C6–C10aryl)2, —P(═O)—O—C1–C6alkyl, —P(═O)—O—C6–C10aryl, —P═O(—O—C1–C6alkyl)2, —P═O(—O—C6–C10aryl)2, —P(—O—C1–C6alkyl)2 and —P(—O—C6–C10aryl)2;
• R1–R4 are each C1–C6alkyl;
• R5 and R6 are each, independently of one another, hydrogen, C1–C6alkyl or C6–C10aryl;
• or
• R5 and R6 are together oxygen;
• Q is a direct bond or a bivalent radical —(CR7R8)— or —(CR7R8—CR9R10)—, where
• R7, R8, R9 and R10 are each, independently of one another, hydrogen or C1–C6alkyl;
• and
• Z1 is oxygen or a bivalent radical —NR11— or —(CR12R13)—, where
• R11 is hydrogen, C1–C6alkyl, C6–C10aryl or the acyl radical Ra as defined above;
• or, independently of one another,
• R12 and R13 are each hydrogen or C1–C6alkyl, or
• one of the radicals R12 and R13 is hydrogen or C1–C6alkyl and the other is C1–C6alkyl, C1–C6alkoxy, C6–C10aryloxy, acyloxy selected from the group consisting of —O—C(═O)—H, —O—C(═O)—C1–C19alkyl, —O—C(═O)—C1–C54alkenyl, —O—C(═O)—C6–C10aryl, —O—C(═O)—C1–C36alkenyl-C6–C10aryl, —O—C(═O)—O—C1–C6alkyl, —O—C(═O)—O—C6–C10aryl, —O—C(═O)—NH—C1–C6alkyl, —O—C(═O)—NH—C6–C10aryl and —O—C(═O)—N(C1–C6alkyl)2, C1–C6alkylamino, di-C1–C6alkylamino, C6–C10arylamino, acylamino selected from the group consisting of —NH—C(═O)—H, —NH—C(═O)—C1–C19alkyl, —NH—C(═O)—C1–C54alkenyl, —NH—C(═O)—C6–C10aryl, —NH—C(═O)—C1–C36alkenyl-C6–C10aryl, —NH—C(═O)—O—C1–C19alkyl, —NH—C(═O)—O—C6–C10aryl, —NH—C(═O)—NH—C1–C6alkyl, —NH—C(═O)—NH—C6–C10aryl and —NH—C(═O)—N(C1–C6alkyl)2, diacylamino selected from the group consisting of —N[—C(═O)—C1–C19alkyl]2, —N[—C(═O)—C6–C10aryl]2, —N[—C(═O)—C1–C6alkylene-C(═O)—], —N[—C(═O)—C2–C6alkenylene-C(═O)—] and phthalimido or N-acyl-N—C1–C6alkylamino;
• or the two radicals R12 and R13 are together oxo;
• or
• a compound of the formula Ib, where
• Ra is an acyl radical selected from the group consisting of —C(═O)—H, —C(═O)—C1–C19alkyl, —C(═O)—C2–C19alkenyl, —C(═O)—C2–C4alkenyl-C6–C10aryl, —C(═O)—C6–C10aryl, —C(═O)—O—C1–C6alkyl, —C(═O)—O—C6–C10aryl, —C(═O)—NH—C1–C6alkyl, —C(═O)—NH—C6–C10aryl and —C(═O)—N(C1–C6alkyl)2;
• R1–R4 are each C1–C6alkyl;
• A are substituents on the phenyl rings;
• and
• m is an integer from one to four;
• or
• a compound of the formula Ic, where
• Ra is an acyl radical selected from the group consisting of —C(═O)—H, —C(═O)—C1–C19alkyl, —C(═O)—C2–C19alkenyl, —C(═O)—C2–C4alkenyl-C6–C10aryl, —C(═O)—C6–C10aryl, —C(═O)—O—C1–C6alkyl, —C(═O)—O—C6–C10aryl, —C(═O)—NH—C1–C6alkyl, —C(═O)—NH—C6–C10aryl, —C(═O)—N(C1–C6alkyl)2, —P(═O)—C1–C19alkyl, —P(═O)2—C1–C19alkyl, —P(═O)—C6–C10aryl, —P═O(—C1–C19alkyl)2, —P═O(—C6–C10aryl)2, —P(═O)—O—C1–C6alkyl, —P(═O)—O—C6–C10aryl, —P═O(—O—C1–C6alkyl)2, —P═O(—O—C6–C10aryl)2, —P(—O—C1–C6alkyl)2 and —P(—O—C6–C10aryl)2;
• Rb is hydrogen, carbamoyl, C1–C6alkylcarbamoyl, di-C1–C6alkylcarbamoyl or is as defined for Ra;
• Rc and Rd are each, independently of one another, hydrogen, C1–C20alkyl or C6–C10aryl;
• and
• R1–R3 are each C1–C6alkyl or C6–C10aryl;
• or
• a compound of the formula:
• where
• n is two;
• X is a direct bond or the monovalent radical of a C1–C18alkylene bridge;
• R1–R4 are each C1–C6alkyl;
• R5 and R6 are each, independently of one another, hydrogen, C1–C6alkyl or C6–C10aryl;
• or
• R5 and R6 are together oxygen;
• Q is a direct bond or a bivalent radical —(CR7R8)— or —(CR7R8—CR9R10)—, where
• R7, R8, R9 and R10 are each, independently of one another, hydrogen or C1–C6alkyl;
• and
• Z1 is oxygen or a bivalent radical —NR11— or —(CR12R13)—, where
• R11 is hydrogen, C6–C10aryl or C1–C6alkyl or, independently of one another,
• one of the radicals R12 and R13 is hydrogen or C1–C6alkyl and the other is C1–C6alkyl, C1–C6alkoxy, C6–C10aryloxy, acyloxy selected from the group consisting of —O—C(═O)—H, —O—C(═O)—C1–C19alkyl, —O—C(═O)—C1–C54alkenyl, —O—C(═O)—C6–C10aryl, —O—C(═O)—C1–C36alkenyl-C6–C10aryl, —O—C(═O)—O—C1–C6alkyl, —O—C(═O)—O—C6–C10aryl, —O—C(═O)—NH—C1–C6alkyl, —O—C(═O)—NH—C6–C10aryl and —O—C(═O)—N(C1–C6alkyl)2, C1–C6alkylamino, di-C1–C6alkylamino, C6–C10arylamino, acylamino selected from the group consisting of —NH—C(═O)—H, —NH—C(═O)—C1–C19alkyl, —NH—C(═O)—C1–C54alkenyl, —NH—C(═O)—C6–C10aryl, —NH—C(═O)—C1–C36alkenyl-C6–C10aryl, —NH—C(═O)—O—C1–C19alkyl, —NH—C(═O)—O—C6–C10aryl, —NH—C(═O)—NH—C1–C6alkyl, —NH—C(═O)—NH—C6–C10aryl and —NH—C(═O)—N(C1–C6alkyl)2, diacylamino selected from the group consisting of —N[—C(═O)—C1–C19alkyl]2, —N[—C(═O)—C6–C10aryl]2, —N[—C(═O)—C1–C6alkylene-C(═O)—], —N[—C(═O)—C2–C6alkenylene-C(═O)—] and phthalimido or N-acyl-N—C1–C6alkylamino;
• or the two radicals R12 and R13 are together oxo;
• or
• a compound of the formula:
• where
• n is two
• Ra is an acyl radical selected from the group consisting of —C(═O)—H, —C(═O)—C1–C19alkyl, —C(═O)—C2–C19alkenyl, —C(═O)—C2–C4alkenyl-C6–C10aryl, —C(═O)—C6–C10aryl, —C(═O)—O—C1–C6alkyl, —C(═O)—O—C6–C10aryl, —C(═O)—NH—C1–C6alkyl, —C(═O)—NH—C6–C10aryl and —C(═O)—N(C1–C6alkyl)2;
• X is a direct bond or the monovalent radical of a C1–C18alkylene bridge;
• R1–R4 are each C1–C6alkyl;
• R5 and R6 are each, independently of one another, hydrogen C1–C6alkyl or C6–C10aryl;
• or
• R5 and R6 are together oxygen;
• and
• Q is a direct bond or a bivalent radical —(CR7R8)— or —(CR7R8—CR9R10)—, where
• R7, R8, R9 and R10 are each, independently of one another, hydrogen or C1–C6alkyl.