Preparation of LLDPE resins and films having low gels

Patent metadata

Field	Value
Publication number	US-10138310-B2
Application number	US-80689310-A
Country	US
Kind code	B2
Filing date	Aug 24, 2010
Priority date	Aug 24, 2010
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

Disclosed is a process for making a linear low density polyethylene (LLDPE) having low gels. The process comprises copolymerizing ethylene with one or more C 3-10 α-olefins to produce an LLDPE resin which has a gel defect area less than 25 ppm. The copolymerization is performed in the presence of a Ziegler-Natta catalyst which comprises an MgCl 2 support, a Ti(IV) complex, and a cyclic ether as an internal electron donor. The Ziegler-Natta catalyst has an Mg/Ti molar ratio greater than or equal to 7.

First claim

What is claimed is:

1. A process for making a linear low density polyethylene resin comprising the steps of:
copolymerizing ethylene with a comonomer selected from 1-butene and 1-hexene, and wherein the comonomer used in an amount within the range of 5-10% by weight of ethylene to produce a linear low density polyethylene;
wherein the copolymerizing step is performed in the presence of hydrogen, an inert gas selected from nitrogen and carbon dioxide, and
a Ziegler-Natta catalyst comprising:
a MgCl 2 support,
a Ti(IV) complex, and
an internal electron donor comprising a cyclic ether; and
wherein Ziegler-Natta catalyst is formed by first contacting the MgCl 2 support with the Ti(IV) complex to form an intermediate product, and the intermediate product is then contacted with the internal electron donor to produce the Ziegler-Natta catalyst;
wherein the Ziegler-Natta catalyst has an Mg/Ti molar ratio greater than or equal to 7, and an internal electron donor/Ti molar ratio between 5 and 20; and
wherein the linear low density polyethylene resin has a gel defect area less than or equal to 25 ppm;
wherein the catalyst is characterized by an X-ray diffraction spectrum which, in the range of 2θ diffraction angles between 5.0° and 20.0°, has at least three main diffraction peaks: 2θ of 7.2±0.2°, 11.5±0.2°, and 14.5±0.2°; and
wherein the peak at 2θ of 7.2±0.2° is most intense and the peak at 11.5±0.2° has an intensity less than 90% of the intensity of the peak at 2θ of 7.2±0.2°.

2. The process of claim 1 , wherein the Ti(IV) complex is TiCl 4 .

3. The process of claim 1 , wherein the Mg/Ti molar ratio is within the range of 10 to 100.

4. The process of claim 3 , wherein the Mg/Ti molar ratio is within the range of 10 to 50.

5. The process of claim 1 , wherein the cyclic ether is tetrahydrofuran.

6. The process of claim 1 , wherein the copolymerization step is performed in the gas phase.

7. The process of claim 1 , wherein the comonomer is 1-butene.

8. The process of claim 1 , wherein the linear low density polyethylene has a density within the range of 0.910 to 0.940 g/cm 3 and a melt index (MI 2 ) within the range of 0.1 to 10 dg/min.

9. The process of claim 8 , wherein the linear low density polyethylene has a density within the range of 0.915 to 0.935 g/cm 3 and an MI 2 within the range of 0.5 to 8 dg/min.

10. The process of claim 1 , further comprising forming a film using a blown film process from the linear low density polyethylene, wherein the film comprises one or more additives selected from a slip agent and an antiblock agent, and wherein the film has a gel defect area less than or equal to 16 ppm.

Assignees

• Mavridis Harilaos
• Beran Debra L
• Golden Jeffrey R
• Pater Joachim T M
• Morini Giampiero
• Equistar Chem Lp

Inventors

• Mavridis Harilaos
• Beran Debra L
• Golden Jeffrey R
• Pater Joachim T M
• Morini Giampiero

Classifications

• C08F210/16 Primary

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

• C08F2500/26

  Use as polymer for film forming · CPC title

• C08F4/6543

  halides of magnesium · CPC title

• C08F4/6545

  and metals of C08F4/64 or compounds thereof · CPC title

• C08F210/08

  Butenes · CPC title