Curable composition for electrical machine, and associated method

Patent metadata

Field	Value
Publication number	US-9911521-B2
Application number	US-201514730510-A
Country	US
Kind code	B2
Filing date	Jun 4, 2015
Priority date	Jun 6, 2014
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

A curable composition for an electrical machine is presented. The curable composition includes: (A) about 10 weight percent to about 30 weight percent of a polyfunctional cyanate ester; (B) about 25 weight percent to about 60 weight percent of a first difunctional cyanate ester, or a prepolymer thereof; (C) about 10 weight percent to about 30 weight percent of a second difunctional cyanate ester, or a prepolymer thereof, and (D) about 5 weight percent to about 25 weight percent of a thermally conductive filler comprising boron nitride. An associated method is also presented.

First claim

The invention claimed is:

1. An electrical machine comprising an electrically insulating encapsulating material, wherein the electrically insulating encapsulating material comprises a cured composition of a curable composition, the curable composition comprising:
(A) about 10 weight percent to about 30 weight percent of a polyfunctional cyanate ester having a structure (I)

wherein “n” is an integer equal to or greater than 1, Y has a structure (i) or (ii):
*R 2 —Ar 2 —OCN, or  (i)

*Ar 2 —OCN,  (ii)

Ar 1 and Ar 2 are independently at each occurrence a C 5 -C 30 aromatic radical, R 1 and R 2 are independently at each occurrence a C 1 -C 3 aliphatic radical or a C 3 -C 20 cycloaliphatic radical, and * represents the bonding site;
(B) about 25 weight percent to about 60 weight percent of a first difunctional cyanate ester having a structure (II), or a prepolymer thereof
NCO—Ar 3 —R 3 —Ar 3 —OCN,  (II)

wherein Ar 3 is a C 5 -C 30 aromatic radical, R 3 is a bond or a C 1 -C 2 aliphatic radical;
(C) about 10 weight percent to about 30 weight percent of a second difunctional cyanate ester having a structure (III), or a prepolymer thereof
NCO—Ar 4 —R 5 —Ar 4 —OCN,  (III)

wherein Ar 4 is a C 5 -C 30 aromatic radical, and R 5 is a C 3 -C 10 aliphatic radical;
(D) about 5 weight percent to about 25 weight percent of a thermally conductive filler comprising boron nitride; and
(E) about 5 weight percent to about 15 weight percent of a toughener, wherein the toughener comprises a thermoplastic polymer, a reactive cyanate ester, or a combination thereof.

2. The electrical machine of claim 1 , wherein the thermoplastic polymer comprises a polyimide.

3. The electrical machine of claim 1 , wherein the toughener comprises a polyimide comprising structural units having a formula (XI):

wherein R 6 is a C 3 -C 10 aliphatic radical; a C 5 -C 30 aromatic radical, or combinations thereof.

4. The electrical machine of claim 1 , wherein the polyfunctional cyanate ester comprises a phenolic novolac cyanate ester, a dicylopentadiene novolac cyanate ester, a 1,2,3-tris(4-cyanatophenyl)-propane, or combinations thereof.

5. The electrical machine of claim 1 , wherein the first difunctional cyanate ester comprises a structure having a formula (IV):

wherein Ar 3 is a C 5 -C 30 aromatic radical.

6. The electrical machine of claim 1 , wherein the second difunctional cyanate ester comprises a prepolymer of a difunctional cyanate ester having a formula (V):
NCO—Ar 4 —R 4 —Ar 4 —OCN  (V)

wherein Ar 4 is a C 5 -C 30 aromatic radical, and R 4 is C 3 -C 20 aliphatic radical.

7. The electrical machine of claim 1 , wherein the second difunctional cyanate ester comprises a prepolymer of a difunctional cyanate ester having a formula (VI):

wherein Ar 4 is a C 5 -C 30 aromatic radical.

8. The electrical machine of claim 1 , further comprising about 25 ppm to about 150 ppm of a catalyst.

9. The electrical machine of claim 8 , wherein the catalyst comprises copper acetylacetonate, cobalt acetylacetonate, aluminum acetylacetonate, or combinations thereof.

10. The electrical machine of claim 1 , wherein the curable composition has a viscosity less than about 5000 centiPoise at 100° C.

11. The electrical machine of claim 1 , wherein a cured composition of the curable composition has a thermal conductivity in a range from about 0.75 W/mK to about 1.2 W/mK.

12. The electrical machine of claim 1 , wherein a cured composition of the curable composition has a glass transition temperature equal to or greater than 280° C.

13. The electrical machine of claim 1 , wherein the electrical machine is selected from the group consisting of a motor, a generator, a transformer, a toroid, an inductor, and combinations thereof.

14. The electrical machine of claim 1 , wherein the electrical machine is a generator, and a stator of the generator comprises the electrically insulating encapsulating material.

15. An electrical machine comprising an electrically insulating encapsulating material, wherein the electrically insulating encapsulating material comprises a cured composition of a curable composition, the curable composition comprising:
(A) about 14 weight percent to about 18 weight percent of a polyfunctional cyanate ester having a structure (I)

wherein “n” is an integer equal to or greater than 1, Y has a structure (i) or (ii)
*R 2 —Ar 2 —OCN, or  (i)

*Ar 2 —OCN,  (ii)

Ar 1 and Ar 2 are independently at each occurrence a C 5 -C 30 aromatic radical, R 1 and R 2 are independently at each occurrence a C 1 -C 3 aliphatic radical or a C 3 -C 20 cycloaliphatic radical, and * represents the bonding site;
(B) about 32 weight percent to about 40 weight percent of a first difunctional cyanate ester having a structure (II), or a prepolymer thereof
NCO—Ar 3 —R 3 —Ar 3 —OCN,  (II)

wherein Ar 3 is a C 5 -C 30 aromatic radical, R 3 is a bond or a C 1 -C 2 aliphatic radical;
(C) about 18 weight percent to about 22 weight percent of a second difunctional cyanate ester having a structure (III), or a prepolymer thereof
NCO—Ar 4 —R 5 —Ar 4 —OCN,  (III)

wherein Ar 4 is a C 5 -C 30 aromatic radical, and R 5 is a C 3 -C 10 aliphatic radical;
(D) about 18 weight percent to about 22 weight percent of a thermally conductive filler comprising boron nitride; and
(E) about 5 weight percent to about 15 weight percent of a toughener, wherein the toughener comprises a thermoplastic polymer, a reactive cyanate ester, or a combination thereof.

Assignees

• Gen Electric

Inventors

• Boden Eugene Pauling
• Flanagan Kevin Warner
• Simon David Andrew
• Yin Weijun
• Zhang Wei
• Mctigue Robert Colin
• Misner Kathryn Amanda
• Yeager Gary William

Classifications

• C08G73/0655

  from polycyanurates · CPC title

• C09J165/00

  Adhesives based on macromolecular compounds obtained by reactions forming a carbon-to-carbon link in the main chain (C09J107/00 - C09J157/00, C09J161/00 take precedence); Adhesives based on derivatives of such polymers · CPC title

• C09K5/14 Primary

  Solid materials, e.g. powdery or granular · CPC title

• C08L79/04

  Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors · CPC title

• H01B3/306

  Polyimides or polyesterimides · CPC title