Sheet-form insulating varnish and producing method therefor, electrical device, and rotary electric machine

Patent metadata

Field	Value
Publication number	US-12043734-B2
Application number	US-202016935320-A
Country	US
Kind code	B2
Filing date	Jul 22, 2020
Priority date	Oct 31, 2019
Publication date	Jul 23, 2024
Grant date	Jul 23, 2024

Abstract

The thermosetting resin composition is used for a sheet-form insulating varnish to be disposed in a gap between insulation target members, and contains: a thermosetting resin (A) that is in solid form at 25° C.; a thermosetting resin (B) that is in liquid form at 25° C.; a latent curing agent that is unreactive at 60° C. or lower; and an inorganic filler having a maximum particle diameter smaller than a dimension of the gap and having an average particle diameter smaller than 0.5 times the dimension of the gap. 30 parts by mass to 70 parts by mass of the thermosetting resin (A) is contained per a total of 100 parts by mass of the thermosetting resin (A) and the thermosetting resin (B). A volume ratio of the inorganic filler to an entirety of the composition is not higher than 50%.

First claim

What is claimed is:

1. A sheet-form insulating varnish to be disposed in a gap between insulation target members, at least a part of the gap having a fixed dimension, formed from a thermosetting resin composition in an uncured or semi-cured state, in a sheet form with predetermined film thickness,
wherein the thermosetting resin composition contains:
a thermosetting resin (A) that is in solid form at 25° C.;
a thermosetting resin (B) that is in liquid form at 25° C.;
a latent curing agent that is unreactive at 60° C. or lower; and
an inorganic filler having a maximum particle diameter smaller than the dimension of the gap and having an average particle diameter smaller than 0.5 times the dimension of the gap, wherein
an amount of the thermosetting resin (A) per a total of 100 parts by mass of the thermosetting resin (A) and the thermosetting resin (B) is in a range of 30 parts by mass to 70 parts by mass, and
a volume ratio of the inorganic filler to an entirety of the composition is not higher than 50%,
wherein the sheet-form insulating varnish has a compression rate that reduces the film thickness by at least 10% under a pressure of 25 MPa at 25° C.,
wherein the sheet-form insulating varnish satisfies at least one of:
(A) the sheet-form insulating varnish has, at 25° C., a storage shear modulus that is in a range of 1.0×10 3 Pa to 5.0×10 4 Pa, and a smallest value of the storage shear modulus is present in a range of 80° C. to 150° C. and is in a range of 10 Pa to 2.0×10 3 Pa, or
(B) the sheet-form insulating varnish has, at 25° C., a complex viscosity that is in a range of 6.0×10 2 Pa·s to 1.0×10 4 Pa·s, and a smallest value of the complex viscosity is present in a range of 80° C. to 150° C. and is not greater than 5.0×10 2 Pa·s.

2. The sheet-form insulating varnish according to claim 1 , wherein each of the thermosetting resin (A) and the thermosetting resin (B) contains at least one of an epoxy resin, a phenolic resin, and an unsaturated polyester resin.

3. The sheet-form insulating varnish according to claim 1 , wherein the thermosetting resin (A) is an epoxy resin having a softening point that is in a range of 50° C. to 160° C.

4. The sheet-form insulating varnish according to claim 1 , wherein the latent curing agent is any of a boron trifluoride-amine complex, dicyandiamide, and an organic acid hydrazide.

5. The sheet-form insulating varnish according to claim 1 , the thermosetting resin composition further containing a curing accelerator that is unreactive at 60° C. or lower.

6. The sheet-form insulating varnish according to claim 1 , the thermosetting resin composition further containing a thermoplastic resin having a weight average molecular weight that is in a range of 10,000 to 100,000, wherein an amount of the thermoplastic resin per a total of 100 parts by mass of the thermosetting resin (A) and the thermosetting resin (B) is in a range of 1 part by mass to 40 parts by mass.

7. The sheet-form insulating varnish according to claim 6 , wherein the thermoplastic resin is a phenoxy resin or a polyester resin.

8. The sheet-form insulating varnish according to claim 1 , wherein the sheet-form insulating varnish is formed from the thermosetting resin composition in an uncured or semi-cured state, in a sheet form with a film thickness that is in a range of 1 μm to 500 μm.

9. The sheet-form insulating varnish according to claim 8 , wherein the film thickness is set to be not smaller than 1.1 times the dimension of the gap.

10. The sheet-form insulating varnish according to claim 8 , wherein a non- volatile content per a total of 100 parts by mass of the sheet-form insulating varnish is not less than 97 parts by mass.

11. The sheet-form insulating varnish according to claim 8 , wherein
the sheet-form insulating varnish has, at 25° C., a storage shear modulus that is in a range of 1.0×10 3 Pa to 5.0×10 4 Pa, and
a smallest value of the storage shear modulus is present in a range of 80° C. to 150° C. and is in a range of 10 Pa to 2.0×10 3 Pa.

12. The sheet-form insulating varnish according to claim 8 , wherein
the sheet-form insulating varnish has, at 25° C., a complex viscosity that is in a range of 6.0×10 2 Pa·s to 1.0×10 4 Pa·s, and
a smallest value of the complex viscosity is present in a range of 80° C. to 150° C. and is not greater than 5.0×10 2 Pa·s.

13. The sheet-form insulating varnish according to claim 8 , wherein, when the sheet-form insulating varnish is disposed in the gap between the members, a force of adhesion with the members is not less than 20 N/m.

14. The sheet-form insulating varnish according to claim 8 , wherein a release film or a release paper sheet is disposed on one surface of the sheet-form insulating varnish.

15. An electrical device comprising: a substrate on which an electronic part is mounted; and a housing to which the substrate is fixed, wherein
(i) the sheet-form insulating varnish according to claim 8 is disposed in a gap between the electronic part and the substrate, wherein the inorganic filler in the thermosetting resin composition from which the sheet-form insulating varnish is formed has a maximum particle diameter smaller than the dimension of the gap between the electronic part and the substrate and has an average particle diameter smaller than 0.5 times the dimension of the gap between the electronic part and the substrate, or
(ii) the sheet-form insulating varnish according to claim 8 is disposed in a gap between the substrate and the housing, wherein the inorganic filler in the thermosetting resin composition from which the sheet-form insulating varnish is formed has a maximum particle diameter smaller than the dimension of the gap between the substrate and the housing and has an average particle diameter smaller than 0.5 times the dimension of the gap between the substrate and the housing.

16. A rotary electric machine in which a stator coil is accommodated in a slot of a stator core, wherein
the sheet-form insulating varnish according to claim 8 is disposed in a gap between the stator coil and an inner wall of the slot, wherein the inorganic filler in the thermosetting resin composition from which the sheet-form insulating varnish is formed has a maximum particle diameter smaller than the dimension of the gap between the stator coil and the inner wall of the slot and has an average particle diameter smaller than 0.5 times the dimension of the gap between the stator coil and the inner wall of the slot.

17. The rotary electric machine according to claim 16 , wherein
an insulating paper sheet is disposed in the gap, and
the sheet-form insulating varnish is disposed on a side of the insulating paper sheet that faces the stator coil, or on each side of the insulating paper sheet.

Assignees

• Mitsubishi Electric Corp

Inventors

• Yasuda Naoki
• Natori Shiori
• Hasegawa Kazuya
• Okamoto Shogo

Classifications

• C08K2003/265

  Calcium, strontium or barium carbonate · CPC title

• C08K2003/2227

  of aluminium · CPC title

• C08K3/36

  Silica · CPC title

• C08K2201/003

  Additives being defined by their diameter · CPC title

• C08L67/00

  Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain (of polyester-amides C08L77/12; of polyester-imides C08L79/08); Compositions of derivatives of such polymers · CPC title