Polypropylene blends and processes for producing polymeric compositions

Patent metadata

Field	Value
Publication number	US-9334374-B2
Application number	US-201314387141-A
Country	US
Kind code	B2
Filing date	Feb 22, 2013
Priority date	Mar 29, 2012
Publication date	May 10, 2016
Grant date	May 10, 2016

Abstract

Polymer blends of polypropylene homopolymer and propylene-α-olefin interpolymer. Processes for producing polymeric compositions comprising control-cooling heated blends of polypropylene and propylene-α-olefin interpolymer. Such polymeric compositions can be employed in forming coated wires and cables.

First claim

The invention claimed is:

1. A process for preparing a thermoplastic polymeric composition, said process comprising:
(a) heating a polymer blend comprising a polypropylene homopolymer and a propylene-α-olefin interpolymer to a melt temperature of (1) greater than 140° C., (2) at least the melting temperature of the polypropylene homopolymer, or (3) at least the melting temperature of the propylene-α-olefin interpolymer, whichever of (1) through (3) is greatest, for a time sufficient to form a polymer melt blend; and
(b) cooling said polymer melt blend from said melt temperature down to ambient temperature, wherein said cooling comprises:
(i) non-control-cooling said polymer melt blend from said melt temperature to an initial cooled temperature in the range of from 140 to 125° C.,
(ii) control-cooling said polymer melt blend at an average cooling rate in the range of from 0.1 to 30° C. per minute from said initial cooled temperature to an intermediate cooled temperature in the range of from 110 to 100° C., and
(iii) cooling, by either control-cooling or non-control-cooling, said polymer melt blend from said intermediate cooled temperature to ambient temperature, thereby forming said polymeric composition.

2. The process of claim 1 , wherein said polymeric composition has an alternating current (“AC”) breakdown strength that is at least 5% greater than an otherwise identical but quench-cooled polymeric composition, as measured on 100 micrometer thick films in accordance with ASTM D-149.

3. The process of claim 1 , wherein said polymeric composition has an AC breakdown strength of at least 100 kV/mm, as measured on 100 micrometer thick films in accordance with ASTM D-149.

4. The process of claim 1 , wherein said polypropylene homopolymer and said polypropylene-α-olefin interpolymer are present in said polymer blend in a weight ratio ranging from 4:1 to 1:4.

5. The process of claim 1 , wherein said initial cooled temperature is 125° C., wherein said intermediate cooled temperature is 110° C., wherein said cooling of step (iii) is non-control-cooling.

6. The process of claim 1 , wherein said control-cooling of step (ii) is performed at a rate in the range of from 1 to 10° C. per minute.

7. The process of claim 1 , further comprising, prior to said cooling of step (b), coating said polymer melt blend on a conductive core thereby forming said polymeric coating on said conductive core following said cooling of step (b).

8. The process of claim 7 , wherein said polymeric coating on said conductive core presents a direct current (“DC”) breakdown strength of at least 400 kV when measured at a thickness of 3.5 mm.

9. The process of claim 1 , wherein said polypropylene homopolymer is non-nucleated.

10. The process of claim 1 , wherein the α-olefin component of said polypropylene-α-olefin interpolymer is ethylene.

Assignees

• Dow Global Technologies Llc
• Univ Southampton
• Gnosys Uk Ltd
• Dow Chemical Co
• Univ Southampton
• Gnosys Global Ltd

Inventors

• Sutton Simon
• Geussens Theo E
• Vaughan Alun
• Stevens Gary

Classifications

• C08L23/12

  Polypropene · CPC title

• C08J2323/12

  Polypropene · CPC title

• B29C48/04

  Particle-shaped (making granules B29B9/00) · CPC title

• B29C48/91

  Heating, e.g. for cross linking · CPC title

• C08L2205/02

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