Claims
- 1. A process for the manufacture of thermally stable, alpha-olefin polymers, which polymers are obtained by means of catalysts prepared by reaction of an aluminum alkyl compound with a solid component selected from a product comprising a titanium compound and a magnesium dihalide in active form, and a product comprising a tetravalent titanium compound supported onto a trivalent titanium halide having a surface area greater than 50 m.sup.2/ g, which process consists in adding before or during polymerization or after polymerization is substantially complete, but before quenching the catalyst, a stabilizer containing in the molecule one or more substituted piperidyl groups having the following general formula:
- wherein R1 are the same or different from each other and are C.sub.1 -C.sub.4 alkyl radicals, tetramethylpiperidyl radicals, or the alkyl radicals, together with the piperidyl carbon atom to which they are bonded, form a C.sub.5 -C.sub.9 cycloalkyl radical; R.sub.2 are the same or different from each other and are hydrogen, C.sub.1 -C.sub.18 alkyl radicals, C.sub.7 -C.sub.18 aralkyl radicals, or said alkyl radicals together with the piperidyl carbon atom to which they are bonded, are a C.sub.5 -C.sub.10 cycloalkyl radical; R.sub.3 are the same or different from each other and are hydrogen, C.sub.1 -C.sub.18 alkyl radicals or C.sub.7 -C.sub.18 aralkyl radicals; R.sub.4 is hydrogen, a C.sub.1 -C.sub.8 alkyl radical or a benzyl radical; Z is hydrogen or C.sub.1 -C.sub.18 alkyl; C.sub.1 -C.sub.12 alkylene; C.sub.3 -C.sub.12 alkenyl; C.sub.3 -C.sub.5 alkynyl; C.sub.7 -C.sub.18 aralkyl; C.sub.2 -C.sub.4 acyl; C.sub.2 -C.sub.18 alkanoyl; C.sub.3 -C.sub.18 alkoxyalkyl; C.sub.3 -C.sub.18 alkenoyl; oxyl; cyanomethyl, and xylylenyl radicals; a radical having valence from 1 to 4 and containing from 1 to 4 hydroxyl groups and, optionally, containing ether, ester, or heterocyclic groups, all the valences of this radical being bonded to the nitrogen of the piperidyl rings; a bivalent radical containing one or more ester or amide groups, and a radical ##STR78## wherein R.sub.5 and R.sub.6 are hydrocarbyl radicals.
- 2. A process according to claim 1, wherein Z in the general formula I is a C.sub.1 -C.sub.12 alkyl, C.sub.3 -C.sub.8 alkenyl, C.sub.7 -C.sub.11 aralkyl, or a bivalent radical containing one or more ester groups wherein the two valences of said radical are bonded to piperidyl rings.
- 3. A process according to claim 1, wherein the stabilizer has formula: ##STR79## wherein n is a whole number from 2 to 100;
- R.sub.1, R.sub.2, R.sub.3, R.sub.4 and Z have the same meaning as in claim 1;
- X is a bivalent organic radical;
- Y is a direct chemical bond, or a bivalent aliphatic, cycloaliphatic, aromatic or heterocyclic organic radical containing N or O, S, P atoms in the chain or in the heterocyclic ring.
- 4. A process according to claim 3 wherein the stabilizer has formula: ##STR80## wherein: n is a whole number from 2 to 20; Z is hydrogen and
- R is ##STR81## or ##STR82## radical; wherein R.sub.5 is a C.sub.1 -C.sub.10 alkyl radical.
- 5. A process according to claim 4 wherein R.sub.5 in formula XXIV of the stabilizer is a --C(CH.sub.3).sub.2 --CH.sub.2 --C(CH.sub.3).sub.3 radical.
- 6. A process according to claim 3 wherein the stabilizer has formula: ##STR83## wherein n is a whole number comprised from 2 to 20, Z is hydrogen and Y is a direct chemical bond or a radical --CH.sub.2 --CH.sub.2 --.
- 7. A process according to claim 1, wherein the stabilizer has formula: ##STR84## wherein n is a whole number from 2 to 100; R.sub.1, R.sub.2, R.sub.3,
- R.sub.4 have the same meaning as in claim 1;
- Z is a C.sub.1 -C.sub.12 alkylene radical or a bivalent radical containing one or more ester or amide groups;
- W is a direct chemical bond or a bivalent organic radical, --N--R radical (wherein R is hydrogen or a C.sub.1 -C.sub.18 alkyl radical), or --O --; Y is a direct chemical bond, or a bivalent aliphatic, cycloaliphatic, aromatic or heterocyclic organic radical containing N, or O, S, P atoms in the chain or in the heterocyclic ring.
- 8. A process according to claim 7 wherein the stabilizer has formula: ##STR85## wherein n is a whole number from 2 to 20.
- 9. A process according to claim 7 wherein the stabilizer has formula: ##STR86## wherein n is a whole number from 2 to 20.
- 10. A process according to claim 1, wherein the stabilizer has formula: ##STR87## wherein n, Y, R.sub.1, R.sub.2, R.sub.3 and R.sub.4 have the same meaning as in claim 1;
- Z is a C.sub.1 -C.sub.12 alkylene radical or a bivalent radical containing one or more ester or amide groups.
- 11. A process according to claim 10 wherein the stabilizer has formula: ##STR88## wherein n is a whole number from 2 to 20.
- 12. A process according to claim 1, wherein the stabilizer has formula: ##STR89## wherein R.sub.1, R.sub.2, R.sub.3 and Z have the same meaning as in claim 1;
- X is a bivalent radical or a bivalent radical containing one or more ester or amide groups.
- 13. A process according to claim 12 wherein the stabilizer has formula: ##STR90## wherein Z is hydrogen or a methyl radical.
- 14. A process according to claim 12 wherein the stabilizer has formula: ##STR91## wherein Z is hydrogen.
- 15. A process according to claim 1, wherein the stabilizer has formula: ##STR92## wherein Z R.sub.1 and R.sub.2 have the same meaning as in claim 1; R is an alkyl, alkenyl or phenyl radical;
- n is a whole number from 1 to 3.
- 16. A process according to claim 15 wherein the stabilizer has formula: ##STR93## wherein L is H, halogen, or a C.sub.1 -C.sub.4 alkyl radical.
- 17. A process according to claim 1, wherein the stabilizer has formula: ##STR94## wherein Q is a bivalent organic radical, such as a C.sub.1 -C.sub.12 alkylene or phenylene radical, or a radical having fromula ##STR95## W is a substituted piperidylamino radical; R is H, a C.sub.1 -C.sub.18 alkyl, or a substituted piperidyl radical.
- y is 1 or zero
- x and m are 1, 2 or 3
- n is 2 or 3
- 18. A process according to claim 17 wherein the stabilizer has general formula: ##STR96## wherein: R.sub.5 is hydrogen, C.sub.1 -C.sub.18 alkyl, or a substituted piperidyl radical;
- R.sub.6 is hydrogen, a C.sub.1 -C.sub.18 alkyl radical or a radical --(CH.sub.2)n--Y wherein n is a whole number from 1 to 12, Y is a --OH or a OR group, R being as hereinafter defined,
- or a ##STR97## group, wherein R is a C.sub.1 -C.sub.18 alkyl radical, R' is a C.sub.1 -C.sub.2 alkyl radical,
- Q is a radical --CH.sub.2 --CH.sub.2 -- or --CH.sub.2 --CH.sub.2 --CH.sub.2 --
- and Z is hydrogen
- 19. A process according to claim 18, wherein in the stabilizer of formula XXXII R.sub.5 is hydrogen, R.sub.6 is an alkyl radical --C.sub.4 H.sub.9, Q is a radical --CH.sub.2 --CH.sub.2 --CH.sub.2 --.
- 20. A process according to claim 1 wherein the stabilizer is added in an amount ranging between 0.01 and 1% by weight, referred to the polymer.
- 21. A process according to claim 1 wherein the alpha-olefin polymers are obtained using stereospecific catalysts comprising the reaction product of an aluminum-alkyl compound with catalytic components comprising a titanium compound and an electron-donor compound, supported on a magnesium dihalide in the active form.
- 22. The process according to claim 1 wherein the alpha-olefin polymers are selected from the group consisting of crystalline linear high density polyethylene, low density polyethylene, polypropylene, propylene-ethylene copolymers containing prevailing amounts of propylene, high impact polypropylene, polybutene and poly(4-methyl-1-pentene); and elastomeric ethylene-propylene copolymers, optionally containing a diene monomer.
BACKGROUND OF THE INVENTION
This application is a continuation-in-part of our application S.N. 07/115657, filed Oct. 27, 1987, now abandoned, which is a continuation of our application S.N. 06/826260, filed Feb. 2, 1986, now abandoned.
Attempts have been made in the past, to stabilize olefin polymers by adding hindered phenolic stabilizers during the polymerization reaction. According to U.S. Pat. No. 3.477.991 monomers containing an ortho-hindered phenolic group are copolymerized with olefins, using a catalyst system based on TiCl.sub.3 and Al-alkyls. The resulting copolymers are reported to have thermal and oxidative stability. According to European patent application no. 3836, the stabilization of polyethylene, produced using chromium-based catalysts, is obtained by addition, during polymerization, of a phenolic type stabilizer.
The direct stabilization during polymerization is of particular interest in the case of the recent processes for the production of polyolefins using high yield stereospecific catalysts supported on activated Mg dichloride. In these processes the resultant polymer is in the form of particles having controlled morphology and size such that a granulation step is not required. The stabilization of olefin polymers by adding the phenolic stabilizer(s) during the polymerization by means of such high yield supported stereospecific catalysts, does not lead, however, to satisfactory results because the phenolic stabilizers adversely affect the catalyst performances, cause a yellowing of the polymer and/or give rise to undesired effects on the polymer morphology. The yellowing due to the presence of some phenolic compounds also occurs when the same are added to the slurry at the end of the polymerization prior to quenching the catalyst
US Referenced Citations (29)
Foreign Referenced Citations (2)
Number |
Date |
Country |
65655 |
Dec 1982 |
EPX |
255181 |
Feb 1988 |
EPX |
Non-Patent Literature Citations (1)
Entry |
Research Disclosure, 85-91, Aug. 1973. |
Continuations (1)
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Number |
Date |
Country |
Parent |
826260 |
Feb 1986 |
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Continuation in Parts (1)
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Number |
Date |
Country |
Parent |
115657 |
Oct 1987 |
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