Stabilization of mixed catalyst polyethylene

Patent metadata

Field	Value
Publication number	US-10563045-B2
Application number	US-201715850017-A
Country	US
Kind code	B2
Filing date	Dec 21, 2017
Priority date	Dec 21, 2017
Publication date	Feb 18, 2020
Grant date	Feb 18, 2020

Abstract

The present disclosure relates to systems including a ternary stabilization package that contains a first phosphite, a second phosphite and a primary antioxidant is used in combination with a polyethylene that is polymerized with a mixed catalyst system that contains two different types of catalysts. In some embodiments the stabilized polyethylene exhibits improved color performance.

First claim

What is claimed is:

1. A process for stabilizing a thermoplastic polyethylene product during melt processing conditions wherein said thermoplastic polyolefin product is prepared with at least two catalyst systems and contains catalyst residues comprising
a) titanium;
b) aluminum from at least one aluminoxane; and
c) magnesium from magnesium chloride;
said process comprising the step of incorporating into said thermoplastic polyolefin a stabilizer package comprising:
(i) a first phosphite defined by the formula (I);

 wherein R 1 , R 2 , R 4 and R 5 are each independently chosen from a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and R 3 is chosen from a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; X is chosen from a single bond, a sulfur atom or a —CHR 6 group (R 6 is chosen from a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms); A is chosen from an alkylene group having 1 to 8 carbon atoms or a *—COR 7 group (R 7 is chosen from a single bond or an alkylene group having 1 to 8 carbon atoms, and * denotes a bonding hand on the side of oxygen); and one of Y and Z is chosen from a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms or an aralkyloxy group having 7 to 12 carbon atoms, and the other one of Y and Z is chosen from a hydrogen atom or an alkyl group having 1 to 8 carbon atoms);
(ii) a second phosphite that is different from said first phosphite; and
(iii) a hindered phenolic antioxidant;

 subjecting said thermoplastic polyethylene product to sufficient temperature to cause it to melt.

2. The process of claim 1 wherein said stabilizer package further comprises an acid neutralizer.

3. The process of claim 1 wherein said catalyst residues include i) from 1 to 15 ppm of titanium; ii) from 10 to 200 ppm of aluminum; and iii) from 10 to 250 ppm of magnesium.

4. The process of claim 1 wherein said first phosphite is 6-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2] dioxaphospepin (CAS Reg. No. 203255-81-6).

5. The process of claim 2 wherein said second phosphite is 2,4 di-tertiary butyl phenyl phosphite.

6. The process of claim 1 wherein said first phosphite, said second phosphite and said hindered phenolic are each added in an amount of from 100 to 2000 parts per million by weight based on the weight of said thermoplastic polyethylene product.

7. The process of claim 1 wherein said thermoplastic polyethylene product is a copolymer of ethylene and at least one olefin chosen from butene, pentene, hexene and octene.

8. The process of claim 1 wherein said thermoplastic polyethylene product has a density of from 0.880 to 0.960 g/cc and a melt index, I 2 , as determined by ASTM D1238 at 190° C./2.16 kg, of from 0.3 to 150 g/10 minutes.

9. The process of claim 6 wherein said melt processing conditions comprise a film extrusion at a temperature of from 200° C. to 320° C.

10. The process of claim 1 wherein said stabilizer formulation contains a hindered amine light stabilizer.

11. A process for preparing a thermoplastic polyethylene product comprising:
1) polymerizing polyethylene, optionally with one or more C 3-10 alpha olefins, under solution polymerization conditions in the presence of a first single site catalyst system comprising an organotitanium catalyst and an aluminoxane cocatalyst to form a first polyethylene solution;
2) polymerizing polyethylene, optionally with one or more C3-10 alpha olefins, under solution polymerization conditions in the presence of a second catalyst system comprising a titanium catalyst; an organoaluminum cocatalyst and magnesium chloride to form a second polyethylene solution;
3) combining said first polyethylene solution and said second polyethylene solution to form a combined polyethylene solution;
4) recovering said thermoplastic polyethylene product from said combined polyethylene solution; and
5) adding to said thermoplastic polyethylene product a stabilizer system comprising:
(i) a first phosphite defined by the formula (I);

wherein R1, R2, R4 and R5 each is independently chosen from a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, and R3 is chosen from a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; X is chosen from a single bond, a sulfur atom or a —CHR6 group (R6 is chosen from a hydrogen atom, an alkyl group having 1 to 8 carbon atoms or a cycloalkyl group having 5 to 8 carbon atoms); A is chosen from an alkylene group having 1 to 8 carbon atoms or a *—COR7 group (R7 is chosen from a single bond or an alkylene group having 1 to 8 carbon atoms, and * denotes a bonding hand on the side of oxygen); and one of Y and Z is chosen from a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms or an aralkyloxy group having 7 to 12 carbon atoms, and the other one of Y and Z is chosen from a hydrogen atom or an alkyl group having 1 to 8 carbon atoms);
(ii) a second phosphite that is different from said first phosphite; and
(iii) a hindered phenolic antioxidant.

12. The process of claim 11 wherein said thermoplastic polyethylene product further comprises an acid neutralizer.

13. The process of claim 11 wherein said thermoplastic polyethylene contains catalyst residues which include i) from 1 to 15 ppm of titanium; ii) from 10 to 200 ppm of aluminum; and iii) from 10 to 250 ppm of magnesium.

14. The process of claim 11 wherein said first phosphite is 6-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2] dioxaphospepin (CAS Reg. No. 203255-81-6).

15. The process of claim 11 wherein said second phosphite is 2,4 di-tertiary butyl phenyl phosphite.

16. The process of claim 11 wherein said first phosphite, said second phosphite and said hindered phenolic are each added in an amount of from 100 to 2000 parts per million by weight based on the weight of said thermoplastic polyethylene product.

17. The process of claim 11 wherein said thermoplastic polyethylene product is a copolymer of ethylene and at least one olefin chosen from butene, pentene, hexene and octene.

18. The process of claim 17 wherein said thermoplastic polyethylene product has a density of from 0.880 to 0.960 g/cc and a melt index, 12, as determined by ASTM D1238 at 190° C./2.16 kg, of from 0.3 to 150 g/10 minutes.

19. The process of claim 11 wherein said stabilizer formulation contains a hindered amine light stabilizer.

Assignees

• Nova Chem Int Sa

Inventors

• Wasylenko Derek
• Tikuisis Tony
• Lightbody Owen
• Waldie Fraser

Classifications

• C08K5/526

  with hydroxyaryl compounds · CPC title

• C08K5/105

  with phenols · CPC title

• C08K5/527 Primary

  Cyclic esters · CPC title

• C08K5/005

  Stabilisers against oxidation, heat, light, ozone · CPC title

• C08L23/0807

  with unsaturated hydrocarbons only containing four or more carbon atoms · CPC title