Blend of bimodal polyethylene with unimodal ultra high molecular weight polyethylene with improved mechanical properties

Patent metadata

Field	Value
Publication number	US-9783661-B2
Application number	US-201514912571-A
Country	US
Kind code	B2
Filing date	Feb 6, 2015
Priority date	Feb 13, 2014
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

High density polyethylene blend, comprising (A) 55 to 99 wt % of a high density multimodal polyethylene component having a density of at least 930 kg/m3, and (B) 1 to 45 wt % of an ultra-high molecular weight polyethylene homo- or copolymer component having (i) an intrinsic viscosity of at least 15.0 dl/g (ii) an a nominal viscosity molecular weight (Mv) of at least 2.0*10 6 g/mol and (iii) a molecular weight of (M w ) of at least 0.7*10 6 g/mol, and wherein said blend has an MFR 21 of 0.05 to 10.0 g/10 min and a density of at least 925 kg/m 3 .

First claim

The invention claimed is:

1. High density polyethylene blend, comprising:
(A) 55 to 99 wt % of a high density multimodal polyethylene component having a density of at least 930 kg/m 3 , and
(B) 1 to 45 wt % of an ultra-high molecular weight polyethylene homopolymer component having
(i) an intrinsic viscosity of at least 15.0 dl/g
(ii) a nominal viscosity molecular weight (M v ) of at least 2.0*10 6 g/mol and
(iii) a molecular weight of (M w ) of at least 0.7*10 6 g/mol,
wherein component (B) is a disentangled ultra-high molecular weight polyethylene homopolymer, which is further characterized by a factor for the normalized elastic modulus G′ 0 /G′ p in the range of 0.20 to 0.95 determined in a dynamic time sweep measurement at 180° C. with constant strain of 0.5% at fixed frequency of 10 rad/s for at least 3600 s, whereby G′ 0 is the elastic shear modulus measured at t 0 directly after melting the sample and G′ p is the maximum plateau modulus; and
wherein said blend has an MFR 21 of 0.05 to 10.0 g/10 min and a density of at least 925 kg/m 3 .

2. A blend as defined in claim 1 , wherein component (A) is a bimodal HDPE having 0.1 to 2 mol % comonomer and an MFR 21 of 1-20 g/10 min.

3. A blend as defined in claim 1 , wherein component (A) comprises an ethylene homopolymer component and a butene or hexene ethylene copolymer component.

4. A blend as defined in claim 1 , wherein component (A) is present in an amount of 80 to 93 wt %.

5. A blend as claimed in claim 1 , wherein the density of the blend is 935 to 970 kg/m 3 .

6. A blend as claimed in claim 1 , wherein the UHMW polyethylene homopolymer component has a complex viscosity η* 0.05 at a shear stress of 0.05 rad/s at 190° C. in the range of 1,000,000 Pa·s to 30,000,000 Pa·s.

7. A blend as claimed in claim 1 , wherein the UHMW polyethylene homopolymer is further characterized by the factor G′ 0 /G′ p in the range of 0.30 to 0.94 in a dynamic time sweep measurement.

8. A blend as claimed in claim 1 , wherein the UHMW polyethylene homopolymer component is an unimodal UHMW polyethylene.

9. A blend as claimed in claim 1 , wherein the UHMW polyethylene homopolymer component is prepared in a slurry polymerization process at 30 to 100° C. by using a Ziegler-Natta catalyst.

10. A blend as claimed in claim 1 , wherein the blend further comprises carbon black in an amount of 1.0 to 10 wt %, based on the total amount of the composition, whereby the carbon black is added in its original form or in the form of a master batch, in which carbon black, and optionally further additives are contained in concentrated form in a carrier polymer.

11. A process for the preparation of a blend as defined in claim 1 comprising mixing
(A) 55 to 99 wt % of a high density multimodal polyethylene component having a density of at least 930 kg/m 3 , and
(B) 1 to 45 wt % of an ultra-high molecular weight polyethylene homopolymer having
(i) an intrinsic viscosity of at least 15.0 dl/g
(ii) a nominal viscosity molecular weight (M v ) of at least 2.0*10 6 g/mol and
(iii) a molecular weight of (M w ) of at least 0.7*10 6 g/mol,
and extruding or kneading the same so as to form a blend having an MFR 21 of 0.05 to 10.0 g/10 min and a density of at least 925 kg/m 3 ;
wherein component (B) is a disentangled ultra-high molecular weight polyethylene homopolymer, which is further characterized by a factor for the normalized elastic modulus G′ 0 /G′ p in the range of 0.20 to 0.95 determined in a dynamic time sweep measurement at 180° C. with constant strain of 0.5% at fixed frequency of 10 rad/s for at least 3600 s, whereby G′ 0 is the elastic shear modulus measured at t 0 directly after melting the sample and G′ p is the maximum plateau modulus.

12. An article made from the polyethylene blend as defined in claim 1 .

13. Method for the production of an article comprising the use of the polyethylene blend according to claim 1 .

Assignees

• Borealis Ag

Inventors

• Dou Qizheng
• Albunia Alexandra Romina
• Liu Yi

Classifications

• C08L2205/02

  containing two or more polymers of the same C08L -group · CPC title

• C08J2323/06

  Polyethene · CPC title

• C08L23/04 Primary

  Homopolymers or copolymers of ethene · CPC title

• C08L23/0815

  with aliphatic 1-olefins containing one carbon-to-carbon double bond · CPC title

• C08J2423/08

  Copolymers of ethene (C08J2423/16 takes precedence) · CPC title