Process to visbreak propylene-based polymers with C—C initiators

Patent metadata

Field	Value
Publication number	US-10316115-B2
Application number	US-201415100510-A
Country	US
Kind code	B2
Filing date	Dec 17, 2014
Priority date	Dec 19, 2013
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

The invention provides a process to prepare a second propylene-based polymer from a first propylene-based polymer, each propylene-based polymer having a melt flow rate (MFR; 2.16 kg/230° C.) with the MFR of the second propylene-based polymer greater than the MFR of the first propylene-based polymer, the process comprising the step of contacting under visbreaking conditions the first propylene-based polymer with at least one carbon-carbon (C—C) free-radical initiator of Structure (I): (Structure (I)) wherein R1, R2, R3, R4, R5 and R6 are each, independently, a hydrocarbyl group or a substituted hydrocarbyl group, and wherein, optionally, two or more R groups (R1, R2, R3, R4, R5 and R6) form a ring structure.

First claim

What is claimed is:

1. A process to prepare a second propylene-based polymer from a first propylene-based polymer, each propylene-based polymer having a melt flow rate (MFR; 2.16kg/230° C.) with the MFR of the second propylene-based polymer greater than the MFR of the first propylene-based polymer, the process comprising the step of contacting under visbreaking conditions in the absence of oxygen and in the absence of oxygen-containing compounds the first propylene-based polymer with at least one carbon-carbon (C-C) free-radical initiator of Structure I:

wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each, independently, a C 1 -C 12 hydrocarbyl group.

2. The process of claim 1 , wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each, independently, a C 1 -C 8 hydrocarbyl group.

3. The process of claim 1 comprising contacting the first propylene-based polymer with from 0.05 wt % to 0.5 wt % C-C free-radical initiator, based on the weight of the first propylene-based polymer.

4. The process of claim 1 , wherein the C-C free-radical initiator has a decomposition temperature of greater than 130° C. based on DSC measurements.

5. The process of claim 1 , comprising contacting the first propylene-based polymer with at least two different C-C free-radical initiators.

6. The process of claim 1 , wherein R 1 and R 4 are each a phenyl group.

7. The process of claim 1 , wherein the at least one C-C free radical initiator is 3,4-diethyl-3,4-diphenyl hexane.

8. The process of claim 1 , wherein the MFR of the second propylene-based polymer is at least 130% of the MFR of the first propylene based polymer.

9. The process of claim 1 , wherein the visbreaking conditions further include contacting the first propylene-based polymer with the C-C free radical initiator under an inert atmosphere.

10. The process of claim 1 , wherein the first propylene-based polymer has a density from 0.83 g/cc to 0.90 g/cc.

11. The process of claim 10 , wherein the first propylene-based polymer has a molecular weight distribution from 3 to 5.

12. The process of claim 1 , wherein the visbreaking conditions further include activating the C-C free radical initiator by radiation.

13. The process of claim 1 wherein the visbreaking conditions further include contacting the first propylene-based polymer with the C-C free radical initiator at a temperature from 200° C. to 350° C.

14. The process of claim 1 , wherein the at least one C-C free radical initiator is selected from the group consisting of 2,3-dimethyl-2,3-diphenyl butane, 3,4-diethyl-3,4-diphenyl hexane, 3,4-diisobutyl-3,4-diphenyl hexane, 3,4-dibenzyl-3,4-ditolyl hexane, 2,7-dimethyl-4,5-diethyl-4,5-diphenyl octane, 3,4-diethyl-3,4-di(dimethylphenyl) hexane, 3,4-dibenzyl-3,4-diphenyl hexane, poly-1,4-diisopropyl benzene, and combinations thereof.

Assignees

• Dow Global Technologies Llc

Inventors

• Karjala Teresa P
• Ewart Sean W
• Demirors Mehmet
• Tilston Michael W

Classifications

• C08F8/50 Primary

  Partial depolymerisation · CPC title

• C08F2500/12

  Melt flow index or melt flow ratio · CPC title

• C08L23/10

  Homopolymers or copolymers of propene · CPC title

• C08F255/02

  on to polymers of olefins having two or three carbon atoms · CPC title

• C08F2810/10

  including a reactive processing step which leads, inter alia, to morphological and/or rheological modifications, e.g. visbreaking · CPC title