Production of blend of polyolefin and organopolysiloxane

Patent metadata

Field	Value
Publication number	US-9527988-B2
Application number	US-201314429004-A
Country	US
Kind code	B2
Filing date	Sep 19, 2013
Priority date	Sep 19, 2012
Publication date	Dec 27, 2016
Grant date	Dec 27, 2016

Abstract

A process for the production of a polymer composition is disclosed. The polymer composition comprises an organopolysiloxane dispersed in a thermoplastic organic polymer liable to thermo-radical degradation or cross-linking when subjected to a high compounding energy at a temperature above its melting point. In a first step (I), a thermoplastic organic polymer and an organopolysiloxane are mixed at a temperature at which both the thermoplastic organic polymer and the organopolysiloxane are in liquid phases to form a masterbatch. In a second step (II), the masterbatch is mixed with further thermoplastic organic polymer to form a polymer composition having a lower concentration of organopolysiloxane than that in the masterbatch. In the first step (I), the thermoplastic organic polymer and the organopolysiloxane are mixed in the presence of an additive capable of inhibiting the thermo-radical degradation or cross-linking of the thermoplastic organic polymer. The organopolysiloxane of the masterbatch remains stable during processing.

First claim

The invention claimed is:

1. A process for the production of a polymer composition comprising an organopolysiloxane dispersed in a thermoplastic organic polymer, wherein:
(I) thermoplastic organic polymer and organopolysiloxane are mixed under shear at a temperature at which both the thermoplastic organic polymer and the organopolysiloxane are in liquid phases and wherein the mixture is cooled to form a masterbatch in solid form containing a dispersion of the organopolysiloxane in a matrix of thermoplastic organic polymer; and
(II) the solid masterbatch is mixed with further thermoplastic organic polymer to form a polymer composition having a lower concentration of organopolysiloxane than that in the solid masterbatch;
wherein in (I) the thermoplastic organic polymer and the organopolysiloxane are mixed under shear at a ratio of 10 to 50 parts by weight of organopolysiloxane to 90 to 50 parts by weight of thermoplastic organic polymer and in the presence of an additive capable of inhibiting the thermo-radical degradation or cross-linking of the thermoplastic organic polymer.

2. The process according to claim 1 , wherein the additive is an antioxidant.

3. The process according to claim 1 , wherein the additive is a sterically hindered phenolic antioxidant.

4. The process according to claim 1 , wherein the additive is present at 0.1% to 2% by weight based on the combined weight of thermoplastic organic polymer and organopolysiloxane in the masterbatch.

5. The process according to claim 1 , wherein the organopolysiloxane is a predominantly linear siloxane polymer having a degree of polymerization greater than 4000.

6. The process according to claim 1 , wherein the thermoplastic organic polymer is a polyolefin.

7. The process according to claim 6 , wherein the polyolefin is polypropylene.

8. The process according to claim 7 , wherein the polypropylene has a melt flow index below 20.

9. The process according to claim 1 , wherein (I) comprises the steps of:
(I)(a) first melting the thermoplastic organic polymer in the presence of the additive; and
(I)(b) mixing the molten thermoplastic organic polymer produced in (I)(a) with the organopolysiloxane under shear.

10. The process according to claim 1 , wherein the thermoplastic organic polymer and organopolysiloxane are mixed under shear in a twin screw extruder at a temperature in the range 180° C. to 250° C. to form an extrudate.

11. The process according to claim 10 , wherein the extrudate is cooled and divided into pellets.

12. A masterbatch for the production of a polymer composition formed by the process according to claim 1 , wherein the masterbatch comprises the thermoplastic organic polymer, the organopolysiloxane and the additive.

13. The process according to claim 1 , wherein the additive is pentaerythritoltetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

14. The process according to claim 1 , wherein an average domain size of the organopolysiloxane phase dispersed in the polymer composition is from 1-10 μm.

15. A process for the production of a polymer composition comprising 10 to 50 parts by weight of an organopolysiloxane dispersed in 90 to 50 parts by weight of a thermoplastic organic polymer, wherein the thermoplastic organic polymer and the organopolysiloxane are mixed under shear at a temperature at which both the thermoplastic organic polymer and the organopolysiloxane are in liquid phases, wherein the thermoplastic organic polymer and the organopolysiloxane are mixed under shear in the presence of an additive capable of inhibiting the thermo-radical degradation or cross-linking of the thermoplastic organic polymer and the mixture is cooled to form a solid masterbatch containing a dispersion of the organopolysiloxane in a matrix of thermoplastic organic polymer, and wherein the solid masterbatch is mixed with further thermoplastic organic polymer to form the polymer composition having a lower concentration of organopolysiloxane than in the masterbatch.

16. The process according to claim 15 , wherein an average domain size of the organopolysiloxane phase dispersed in the polymer composition is from 1-10 μm.

17. The process according to claim 15 , wherein the additive is a sterically hindered phenolic antioxidant, alternatively wherein the additive is pentaerythritoltetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

18. A process for stabilising an organopolysiloxane during mixing of the organopolysiloxane with a thermoplastic organic polymer, said mixing being at a temperature above the melting point of the thermoplastic organic polymer, wherein the organopolysiloxane and the thermoplastic organic polymer are mixed under shear at a ratio of 10 to 50 parts by weight of organopolysiloxane to 90 to 50 parts by weight of thermoplastic organic polymer and in the presence of an additive capable of inhibiting the thermo-radical degradation or cross-linking of the thermoplastic organic polymer and the mixture is cooled to form a solid masterbatch containing a dispersion of the organopolysiloxane in a matrix of thermoplastic organic polymer, and wherein the solid masterbatch is mixed with further thermoplastic organic polymer to form the polymer composition having a lower concentration of organopolysiloxane than in the masterbatch.

19. The process according to claim 18 , wherein the additive is a sterically hindered phenolic antioxidant, alternatively wherein the additive is pentaerythritoltetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

Assignees

• Multibase Sa
• Multibase Inc
• Dow Corning

Inventors

• Habimana Jean De La Croix
• Hays Ted
• Prele Patrick

Classifications

• C08K5/1345

  Carboxylic esters of phenolcarboxylic acids · CPC title

• C08L23/12 Primary

  Polypropene · CPC title

• C08L2207/04

  Thermoplastic elastomer · CPC title

• C08L83/04

  Polysiloxanes · CPC title

• C08J3/005

  Processes for mixing polymers · CPC title