NOVEL BIMODAL RESINS HAVING GOOD FILM PROCESSABILITY

• US 20160032027A1
• Filed: 07/29/2014
• Published: 02/04/2016
• Est. Priority Date: 07/29/2014
• Status: Active Grant

• Current Assignee: Chevron Phillips Chemical Company LP (Chevron Corp.)
• Original Assignee: Chevron Phillips Chemical Company LP (Chevron Corp.)
• Inventors: St. Jean, Guylaine, Yang, Qing, Lanier, J. Todd
• Granted Patent: US 9,284,389 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C08F 10/14 Monomers containing five or more carbon atoms
• CPC Class Codes: C08F 210/14 Monomers containing five or more carbon atoms
• CPC Class Codes: C08F 210/16 Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• CPC Class Codes: C08F 2500/04 Broad molecular weight distribution, i.e. Mw/Mn > 6
• CPC Class Codes: C08F 2500/05 Bimodal or multimodal molecular weight distribution
• CPC Class Codes: C08F 2500/07 High density, i.e. > 0.95 g/cm3
• CPC Class Codes: C08F 2500/12 Melt flow index or melt flow ratio
• CPC Class Codes: C08F 2500/17 Viscosity
• CPC Class Codes: C08F 2500/26 Use as polymer for film forming
• CPC Class Codes: C08F 4/65904 in combination with another component of C08F4/64
• CPC Class Codes: C08F 4/65916 supported on a carrier, e.g. silica, MgCl2, polymer
• CPC Class Codes: C08F 4/65925 two cyclopentadienyl rings being mutually non-bridged
• CPC Class Codes: C08F 4/65927 two cyclopentadienyl rings being mutually bridged
• CPC Class Codes: C08L 2203/16 used for films
• CPC Class Codes: C08L 2205/025 containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
• CPC Class Codes: C08L 23/0815 Copolymers of ethene with aliphatic 1-olefins
• CPC Class Codes: C08L 2314/06 Metallocene or single site catalysts

Abstract

A bimodal polyethylene copolymer comprising a lower molecular weight (LMW) component and a higher molecular weight (HMW) component, the copolymer having a z-average molecular weight (M_Z) of from about 1,000 kg/mol to about 2,500 kg/mol, a weight fraction of the LMW component (LMW fr.) of from about 0.60 to 0.85, a ratio of a weight average molecular weight (M_W) of the HMW component (HMW M_W) to a M_W of the LMW component (LMW M_W) of from about 14 to about 25, a zero shear viscosity (η₀) of from about 5×10⁵ Pa-s to about 1×10⁷ Pa-s and a HMW M_W of from about 800 kg/mol to about 1,500 kg/mol.

Claims

1. A bimodal polyethylene copolymer comprising a lower molecular weight (LMW) component and a higher molecular weight (HMW) component, the copolymer having a z-average molecular weight (M_Z) of from about 1,000 kg/mol to about 2,500 kg/mol, a weight fraction of the LMW component (LMW fr.) of from about 0.60 to 0.85, a ratio of a weight average molecular weight (M_W) of the HMW component (HMW M_W) to a M_W of the LMW component (LMW M_W) of from about 14 to about 25, a zero shear viscosity (η

₀) of from about 5×

10⁵ Pa-s to about 1×

10⁷ Pa-s and a HMW M_W of from about 800 kg/mol to about 1,500 kg/mol, wherein the copolymer is prepared using a residence time in a polymerization reactor of equal to or greater than about 30 minutes.

2. The copolymer of claim 1 having a processability characterized by a pressure index of greater than about (1.1×

η

₁₀₀+50) and a bubble stability index of less than about (0.96×

(η

₀/10000)−

15), wherein η

₁₀₀ is the viscosity of the copolymer expressed in Pa-s and measured at 190°

C. and a shear rate of 100 rad/s.

3. The copolymer of claim 2 wherein the pressure index is defined by following equation:

pressure index=5737−

563*(HMW M_W/LMW M_W)−

209*(HMW fr./LMW fr.)+7*M_Z−

1234*M_Z/M_W+404*(HMW M_W/LMW M_W*HMW fr./LMW fr.)−

0.22*(HMW M_W/LMW M_W*M_Z) +139*(HMW M_W/LMW M_W*M_Z/M_W)+2*(HMW fr./LMW fr.*M_Z)−

1591*(HMW fr./LMW fr.*M_Z/M_W)−

0.64*(M_Z*M_Z/M_W), wherein HMW fr. is a weight fraction of the HMW component.

4. The copolymer of claim 2 wherein the bubble stability index is defined by following equation:

bubble stability index=1.31×

10⁴−

2.76×

10³*(HMW M_W/LMW M_W)−

1.46×

10⁵*(HMW fr./LMW fr.)+4.16×

10²*M_Z−

2.43×

10⁴*M_Z/M_W.

5. The copolymer of claim 1 comprising an alpha olefin comonomer.

6. The copolymer of claim 5 wherein the alpha olefin comonomer comprises 1-hexene.

7. The copolymer of claim 1 having a M_W from about 200 kg/mol to 600 kg/mol.

8. The copolymer of claim 1 having a M_Z/M_W ratio from about 4 to about 8.

9. The copolymer of claim 1 having a M_W/M_n ratio of from about 10 to about 25.

10. The copolymer of claim 1 wherein the LMW component has a weight average molecular weight of from about 40 kg/mol to about 80 kg/mol.

11. The copolymer of claim 1 wherein the HMW component has a weight average molecular weight of from about 1,000 kg/mol to about 1,450 kg/mol.

12. The copolymer of claim 1 which when tested in accordance with ASTM D1238 has a high load melt index (I₂₁₆) of from about 8 g/10 min to about 30 g/10 min.

13. The copolymer of claim 1 which when tested in accordance with ASTM D1505 has a density of from about 0.930 g/cc to about 0.950 g/cc.

14. The copolymer of claim 1 having a η

₁₀₀ of from about 1,000 Pa-s to about 2,500 Pa-s.

15. The copolymer of claim 1 having a number average molecular weight (M_n) of from about 15 kg/mol to about 30 kg/mol.

16. The copolymer of claim 1 having a HMW fr./LMW fr. ratio of from about 0.20 to about 0.50, wherein HMW fr. is a weight fraction of the HMW component.

17. The copolymer of claim 1 which when tested in accordance with ASTM D1709 has a dart drop strength ranging from about 100 g to about 450 g.

18. The copolymer of claim 1 which when tested in accordance with ASTM D1922 has an Elmendorf tear strength in the machine direction ranging from about 25 g to about 75 g.

19. The copolymer of claim 1 which when tested in accordance with ASTM D1922 has an Elmendorf tear strength in the transverse direction ranging from about 300 g to about 500 g.

20. A film made from the copolymer of claim 1.

21. A food packaging comprising the film of claim 20.