US 6,020,056 AGranted

Polyethylene terephthalate film for electrical insulation

AssigneeE. I. Du Pont de Nemours and Company

InventorsCharles C. Walker, Rameshchadra M. Gohil

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Abstract

A polyethylene terephthalate film suited for motor insulation is described having the following: (a) an intrinsic viscosity of 0.80; (b) a lateral crystalline size of not greater than 65 Angstroms; (c) an extractable oligomer content of no more than 0.6% by wt.; (d) a hydrolytic lifetime of at least 500 hours; (e) a density within the range from 1.385 to 1.395; (f) no more than 3% by weight comonomer; (g) no more then 1.5% by weight of diethylene glycol as a comonomer; (h) a carboxyl content of no more than 25 milliequivalents per gram of polymer; (i) a particulate content of 0.1 to 2 weight % with the proviso that the polyethylene terephthalate film does not contain an end capping agent; and (j) an embrittlement time at 160.degree. C. of more than 100 days.

Claims2

Dependent claims

An electrical motor containing an insulator of a biaxially oriented, heat set film of polyethylene terephthalate having the following:

(a) an intrinsic viscosity of at least 0.80;
(b) a lateral crystallite size of not greater than 65 Angstrom;
(c) an extractable oligomer content of no more than 0.6% by weight in xylene;
(d) a hydrolytic lifetime of at least 500 hours;
(e) a density within the range from 1.385 to 1.395 gm/cc;
(f) no more than 3% by weight of comonomer;
(g) no more than 1.5% by weight of diethylene glycol as a comonomer;
(h) a carboxyl content of no more than 25 milliequivalents per gram of polymer;
(i) an inorganic particulate content of 0.1 to 2 weight % with the particulate having an average diameter of from 0.05 to 3.5 microns, with the proviso that the polyethylene terephthalate does not contain an end capping agent;
and
(j) an embrittlement time at 160.degree. C. of more than 100 days.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/956,228Filed 22 Oct 1997 · continuation
Priority: 19 Apr 1995
Granted: 1 Feb 2000
Term ends: Not estimatedThe source records don’t support an estimate.

Classification14 codes

C08G 63/00
Macromolecular compounds obtained by reactions forming a carboxylic ester link in the
C08J 5/18
Manufacture of articles or shaped materials containing macromolecular substances: manufacture of films or sheets
H02K 1/04
Details of the magnetic circuit: characterised by the material used for insulating the magnetic circuit or parts thereof
H02K 3/30
Details of windings: windings characterised by the insulating material