# US 10,370,569 B2 · Composition for bonding windings or core laminates in an electrical machine, and associated method

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- Number: US 10,370,569 B2
- Document ID: US10370569B2
- Status: Granted
- Kind: B2
- Application number: 15/864,073
- Filed: 2018-01-08
- Published: 2018-05-10
- Granted: 2019-08-06
- Earliest claimed: 2014-06-06
- Assignees: General Electric Company
- Applicants: General Electric Company
- Inventors: Weijun Yin; Gary William Yeager; Kevin Warner Flanagan; David Andrew Simon; Eugene Pauling Boden; Kathryn Amanda Misner
- Web page: https://patentgrep.com/patent/US10370569B2

## CPC

- C09J 165/00: 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
- B05D 3/0254: {After-treatment}
- B05D 3/0493: {using vacuum}
- C08G 61/12: Macromolecular compounds containing atoms other than carbon in the main chain of the macromolecule
- C08G 73/0655: {from polycyanurates}
- C08L 79/04: Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C08G 2261/12: Copolymers
- C08G 2261/312: Non-condensed aromatic systems, e.g. benzene
- C09K 5/14: Solid materials, e.g. powdery or granular
- C09J: ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES (preparation of glue or gelatine C09H)
- B05D: PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL (conveying articles or workpieces through baths of liquid B65G, e.g. B65G49/02)
- C08G: MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08L: COMPOSITIONS OF MACROMOLECULAR COMPOUNDS (compositions based on polymerisable monomers C08F, C08G; artificial filaments or fibres D01F; textile treating compositions D06)
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE

## Abstract

A curable composition for bonding windings or core laminates in an electrical machine is presented. The curable composition includes: (A) about 10 weight percent to about 25 weight percent of a polyfunctional cyanate ester; (B) about 35 weight percent to about 65 weight percent of a first difunctional cyanate ester, or a prepolymer thereof; (C) about 15 weight percent to about 40 weight percent of a second difunctional cyanate ester, or a prepolymer thereof. An associated method is also presented.

## Claims

### Claim 1

A method for bonding a winding or a core laminate of an electrical machine, comprising:
impregnating the winding or the core laminate with a curable composition, comprising:
(A) about 10 weight percent to about 25 weight percent of a polyfunctional cyanate ester having a structure (I)
NCO—Ar1R1Y—R1nAr1—OCN, (I)
wherein “n” is an integer equal to or greater than 1, Y has a structure (i) or (ii)
*R2—Ar2—OCN, or (i)
*Ar2—OCN, (ii)
Ar1 and Ar2 are independently at each occurrence a C5-C30 aromatic radical, R1 and R2 are independently at each occurrence a C1-C3 aliphatic radical or a C3-C20 cycloaliphatic radical, and * represents the bonding site;
(B) about 35 weight percent to about 65 weight percent of a first difunctional cyanate ester having a structure (II), or a prepolymer thereof
NCO—Ar3—R3—Ar3—OCN, (II)
wherein Ar3 is a C5-C30 aromatic radical, R3 is a bond or a C1-C2 aliphatic radical; and
(C) about 15 weight percent to about 40 weight percent of a second difunctional cyanate ester having a structure (III), or a prepolymer thereof
NCO—Ar4—R5—Ar4—OCN, (III)
wherein Ar4 is a C5-C30 aromatic radical, and R5 is a C3-C10 aliphatic radical;
applying a vacuum to the winding or the core laminate; and
heating the winding or the core laminate of the electrical machine to cure the curable composition and form a bonding material comprising the cured composition, wherein the electrical machine is selected from the group consisting of a motor, a generator, a transformer, a toxoid; an inductor, and combinations thereof.

### Claim 2 (depends on 1)

The method of claim 1, wherein the curable composition is substantially free of a solvent.

### Claim 3 (depends on 1)

The method of claim 1, wherein the curable composition further comprises a solvent.

### Claim 4 (depends on 1)

The method of claim 1, wherein a cured composition of the curable composition shows thermal dimensional stability such that the cured composition has less than 60 percent mean density change after heating at 280° C. for a time period greater than about 500 hours.

### Claim 5 (depends on 1)

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

### Claim 6 (depends on 1)

The method of claim 1, wherein the first difunctional cyanate ester comprises a structure having a formula (IV):
wherein Ar3 is a C5-C30 aromatic radical.

### Claim 7 (depends on 1)

The method of claim 1, wherein the second difunctional cyanate ester comprises a prepolymer of a difunctional cyanate ester having a formula (V):
NCO—Ar4—R4—Ar4—OCN, (V)
wherein Ar4 is a C5-C30 aromatic radical, and R4 is C3-C20 aliphatic radical.

### Claim 8 (depends on 1)

The method of claim 1, wherein the second difunctional cyanate ester comprises a prepolymer of a difunctional cyanate ester having a formula (VI):
wherein Ar4 is a C5-C30 aromatic radical.

### Claim 9 (depends on 1)

The method of claim 1, wherein the curable varnish composition has a viscosity less than about 1000 centiPoise at 70° C.

### Claim 10 (depends on 1)

The method of claim 1, wherein a cured varnish composition of the curable composition has a crack resistance such that the average number of cracks having a dimension greater than 2 mm in length is equal to or less than one.