Recyclable thermoplastic insulation with improved breakdown strength

Patent metadata

Field	Value
Publication number	US-9404005-B2
Application number	US-201113822245-A
Country	US
Kind code	B2
Filing date	Sep 23, 2011
Priority date	Sep 30, 2010
Publication date	Aug 2, 2016
Grant date	Aug 2, 2016

Abstract

The disclosure provides a process for producing a material with improved breakdown strength. The process includes heating a polymeric composition composed of a low density polyethylene (LDPE) and a minority amount of a high density polyethylene (HDPE). The polymeric composition is heated to at least the melting temperature of the HDPE. The process includes control-cooling the heated polymeric composition at a cooling rate from 0.1° C./min to 20° C./min, and forming a polymeric composition. The control-cooled polymeric composition has a unique morphology which improves breakdown strength. Also provided is a coated conductor with an insulating layer composed of the polymeric composition with the unique morphology. The insulating layer exhibits improved breakdown strength.

First claim

What is claimed is:

1. A process comprising:
heating a polymeric composition consisting of (i) a low density polyethylene having a melting temperature of at least 105° C. to 125° C. (LDPE) (ii) a minority amount of a high density polyethylene having a melting temperature of at least 130° C. to 134° C. (HDPE), and (iii) optional antioxidant, to at least the melting temperature of the HDPE;
control-cooling the heated polymeric composition at a cooling rate from 0.1° C./min to 10° C./min; and
forming a polymeric composition having a space-filling array of HDPE lamellae, which are separated by the LDPE, the polymeric composition having an AC breakdown strength greater than 170 kV/mm as measured on 85 micrometer thin films in accordance with ASTM D 149.

2. The process of claim 1 comprising:
melt blending from about 5 wt % to about 35 wt % HDPE and from about 95 wt % to about 65 wt % of the LDPE, and
forming the polymeric composition.

3. The process of claim 1 comprising heating the polymeric composition to at least 130° C.; and control-cooling from 130° C. to 90° C.

4. The process of claim 1 comprising heating the polymeric composition to at least 130° C.; and
control-cooling the heated polymeric composition at a rate from 0.1° C./min to 10° C./min from 130° C. to 90° C.

5. The process of claim 1 comprising heating the polymeric composition to at least 130° C.;
control-cooling from 130° C. to 90° C.; and
quenching when the temperature of the heated polymeric composition is less than 105° C.

Assignees

• Sutton Simon
• Geussens Theo E
• Vaughan Alun
• Stevens Gary
• Dow Global Technologies Llc
• Dow Chemical Co
• Univ Southampton
• Gnosys Global Ltd

Inventors

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

Classifications

• C08L23/06 Primary

  Polyethylene · CPC title

• C09D123/06 Primary

  Polyethylene · CPC title

• H01B3/307

  Other macromolecular compounds · CPC title

• C08L2205/02

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

• C08L2666/06

  Homopolymers or copolymers of unsaturated hydrocarbons; Derivatives thereof · CPC title