Process for the preparation of heterophasic propylene polymer compositions

Patent metadata

Field	Value
Publication number	US-9752023-B2
Application number	US-201214358753-A
Country	US
Kind code	B2
Filing date	Nov 7, 2012
Priority date	Nov 17, 2011
Publication date	Sep 5, 2017
Grant date	Sep 5, 2017

Abstract

Preparing propylene polymer compositions comprising 50 to 90% by weight of a propylene (co)polymer, and 10 to 50% by weight of an ethylene copolymer. The polymerization process includes, in the presence of a catalyst system:
(i) a first step of polymerizing propylene to produce the propylene (co)polymer; and (ii) a successive gas-phase polymerization step performed in the presence of the propylene (co)polymer, ethylene, and one or more α-olefins to produce the ethylene copolymer.

The catalyst system contains the product obtained by contacting:
(a) a solid catalyst component comprising at least two internal electron donor compounds, a succinate and a 1,3-diether; (b) an aluminum hydrocarbyl compound, and (c) optionally, an external electron donor compound.

First claim

What is claimed is:

1. A process for the preparation of a propylene polymer composition comprising:
(A) 50-90% by weight of a propylene (co)polymer, wherein the propylene (co)polymer contains a fraction that is insoluble in xylene at 25° C., and
(B) 10-50% by weight of an ethylene copolymer, wherein the ethylene copolymer contains a fraction that is soluble in xylene at 25° C.;
wherein the propylene polymer composition has a total ethylene content from 5-10 wt. %, based upon the total weight of the propylene polymer composition, and a flexural modulus greater than 1200 MPa;
said process comprising:
(i) a first step of polymerizing propylene in the optional presence of ethylene and/or C 4 -C 10 alpha olefins, to produce the propylene (co)polymer, wherein the propylene (co)copolymer contains a fraction that is insoluble in xylene at 25° C.; and
(ii) a successive gas-phase copolymerizing step, carried out in the presence of the propylene (co)polymer, a mixture of ethylene and one or more α-olefins CH 2 ═CHR in which R is a hydrocarbon radical having 1-10 carbon atoms, to produce the ethylene copolymer;

the process being carried out in the presence of a catalyst system comprising the product obtained by contacting:
(a) a solid catalyst component comprising a magnesium halide, a titanium compound having at least a Ti-halogen bond and at least two internal electron donor compounds,
wherein the at least two internal electron donor compounds comprise a succinate as a first internal electron donor present in an amount from 35-90% by mol with respect to the total amount of internal electron donor compounds present in the solid catalyst component, and a 1,3-diether comprises the second internal electron donor, wherein the total concentration of the internal electron donors is lower than 14.0% by weight with respect to the total weight of the solid catalyst component;

(b) triethylaluminum; and
(c) optionally, an external electron donor compound at a molar ratio of 5-500 with respect to triethylaluminum.

2. The process according to claim 1 , wherein the catalyst component (a) has an average particle size ranging from 15 to 80 μm.

3. The process according to claim 1 , wherein the succinate is present in amount ranging from 45 to 90% by mol with respect to the total amount of internal donors.

4. The process according to claim 1 , wherein step (i) is carried out in liquid propylene.

5. A molded article obtained from a propylene polymer composition produced by the process of claim 1 .

6. The molded article of claim 5 , wherein the molded article is a food storage container.

Assignees

• Basell Poliolefine Italia Srl

Inventors

• Galvan Monica
• Pantaleoni Roberto
• Fusco Ofelia
• Gaddi Benedetta
• Neumann Andreas
• Mazzucco Antonio
• Collina Gianni
• Ciarafoni Marco

Classifications

• C08F2/001

  Multistage polymerisation processes characterised by a change in reactor conditions without deactivating the intermediate polymer (C08F295/00, C08F297/00 take precedence) · CPC title

• C08F10/06

  Propene · CPC title

• C08F4/6543

  halides of magnesium · CPC title

• C08F210/16

  Copolymers of ethene with alpha-alkenes, e.g. EP rubbers · CPC title

• C08F2/00

  Processes of polymerisation · CPC title