Treatment of micropores in mica materials

• US 7,955,661 B2
• Filed: 01/23/2007
• Issued: 06/07/2011
• Est. Priority Date: 06/14/2005
• Status: Expired due to Fees

• Current Assignee: Siemens Energy Incorporated (Siemens AG)
• Original Assignee: Siemens Energy Incorporated (Siemens AG)
• Inventors: Wood, John W., Smith, James D. B., Stevens, Gary
• Primary Examiner(s): FLETCHER III, WILLIAM P
• Application Number:
  US11/656,727
• Publication Number:
  US 20070114704A1
• Time in Patent Office: 1,596 Days
• Field of Search: 427/407.1, 427/385.5, 427/372.2, 427/430.1, 264/643, 428/304.4, 428/325, 428/308.8, 428/332, 428/366, 428/90, 523/400
• US Class Current: 427/407.1
• CPC Class Codes: D21H 13/44 Flakes, e.g. mica, vermiculite
• CPC Class Codes: D21H 17/13 Silicon-containing compounds
• CPC Class Codes: D21H 17/20 Macromolecular organic compounds
• CPC Class Codes: D21H 25/005 Mechanical treatment D21H25/08, D21H25/18 take precedence
• CPC Class Codes: D21H 27/00 Special paper not otherwise provided for, e.g. made by multi-step processes
• CPC Class Codes: H01F 27/2871 Pancake coils
• CPC Class Codes: H01F 41/127 Encapsulating or impregnating encapsulating coil and core H01F41/005
• CPC Class Codes: H01L 21/02107 Forming insulating materials on a substrate
• CPC Class Codes: H01L 21/316 composed of oxides or glassy oxides or oxide based glass
• CPC Class Codes: H02K 3/40 for high voltage, e.g. affording protection against corona discharges
• CPC Class Codes: H02K 9/227 Heat sinks
• CPC Class Codes: H05K 1/0373 containing additives, e.g. fillers H05K1/036 takes precedence
• CPC Class Codes: H05K 2201/0209 Inorganic, non-metallic particles
• CPC Class Codes: H05K 2201/0248 Needles or elongated particles; Elongated cluster of chemically bonded particles microfibers H05K2201/0251; stacked conductors H05K2201/0379
• CPC Class Codes: Y10T 428/249953 Composite having voids in a component [e.g., porous, cellular, etc.]

Abstract

A method for the treatment of micro pores within a mica paper that includes: obtaining a silane with a molecular weight of between approximately 15 and 300, adding the silane to the mica paper, and reacting the silane with the inner surface of the micro pores within the mica paper. After this, a resin is impregnated into the mica paper, and the resin binds to the inner surfaces of the micro pores with the mica paper through the silane. In one embodiment, the mica paper is compressed by an amount between 5% and 30% of its original thickness. In another embodiment, the mica paper is compressed both prior to reacting the silane and during impregnation with the resin.

Claims

1. A method for the treatment of micro pores within a mica paper comprising:

adding silane compounds to the mica paper such that the silane compounds travel within the micro pores of the mica paper, wherein the silane compounds have a molecular weight between approximately 15 and 300;

compressing the mica paper to contact mica flakelet surfaces of the mica paper with one another;

reacting the silane compounds with inner surfaces of the micro pores within the mica paper;

after said reacting, impregnating the mica paper with a resin;

wherein during said compressing, the mica paper is compressed by an amount between 5% and 30% of the original thickness of the mica paper prior to said compressing thereby yielding a desired degree of exposure of the contacted mica flakelet surfaces to the silane compounds with respect to a time necessary for the silane compounds to reach the micro pores of the mica paper for said reacting; and

wherein during said impregnating, the resin binds to the inner surfaces of the micro pores with the mica paper through the silane compounds to increase adhesion of the impregnating resin to the mica paper and to reduce micro void formation in the impregnated mica paper.

2. The method of claim 1, wherein the silane compounds are added to the mica paper by contacting the mica paper with a solution comprising the silane compounds and a solvent for the silane compounds.

3. The method of claim 2, wherein the solvent is substantially removed prior to said impregnating.

4. The method of claim 1, wherein the silane compounds comprise at least one of silane (SiH4), silanol (SiH3OH), methylsilane (SiH3CH3), vinylsilane (SiH3CHCH2), aminosilane (SiH3NH2), alkoxysilane (SiH3OR) or epoxysilane.

5. The method of claim 1, wherein the silane compounds comprise at least one of amino methyl trimethyl silane, 3-glycidyl oxy propyl trimethoxy silane, vinyl dimethyl silane, or allyl trimethyl silane.

6. The method of claim 1, wherein the silane compounds comprise compounds having a molecular weight of between 32-90, and wherein the compounds having a molecular weight of between 32-90 have an increased tendency to travel into the micro pores of the mica paper relative to larger molecular weight silane compounds.

7. The method of claim 1, wherein the silane compounds comprise compounds having a molecular weight of between 100-300, and wherein the silane compounds having a molecular weight of between 100-300 have a decreased tendency to be disposed between contacted mica surfaces in the mica paper relative to lower molecular weight silane compounds.

8. The method of claim 7, wherein during said adding, the silane compounds comprise a plurality of silane compounds of different molecular weights.

9. The method of claim 1, wherein the impregnating resin comprises nanofillers.

10. The method of claim 9, wherein the nanofillers comprise 1-60% of the resin by weight.

11. The method of claim 9, wherein at least some of the nanofillers comprise surface functional groups that react with the silane compounds in the mica paper.

12. The method of claim 1, wherein said compressing is done prior to said adding silane compounds.

13. The method of claim 12, further comprising additionally compressing the mica paper after said adding to remove excess silane compounds.

14. A method for the treatment of micro pores within a mica paper comprising:

adding silane compounds to the mica paper such that the silane compounds travel within the micro pores of the mica paper, wherein the silane compounds have a molecular weight between approximately 15 and 300;

compressing the mica paper to contact mica flakelet surfaces of the mica paper with one another and to reduce the likelihood of the silane compounds being disposed between the contacted mica flakelet surfaces of the mica paper during said adding;

reacting the silane compounds with inner surfaces of the micro pores within the mica paper;

after said reacting, impregnating the mica paper with a resin;

additionally compressing the mica paper during said impregnating of the resin, wherein an amount of compression for the additional compression is approximately the same as an amount of compression to contact mica flakelet surfaces of the mica paper with one another;

wherein during said impregnating, the resin binds to the inner surfaces of the micro pores with the mica paper through the silane compounds to increase adhesion of the resin to the mica paper and to reduce microvoid formation in the impregnated mica paper.

15. The method of claim 14, wherein during said compressing the mica paper to contact mica flakelet surfaces of the mica paper with one another, an amount of compression of the mica paper is between 5-30% of a thickness of the mica paper prior to said compressing.

16. The method of claim 14, wherein said compressing the mica paper to contact mica flakelet surfaces of the mica paper with one another is done prior to said adding silane compounds.

17. The method of claim 16, wherein the silane compounds are added to the mica paper by contacting the mica paper with a solution comprising the silane compounds and a solvent for the silane compounds, and wherein the mica paper is substantially dried of the solution prior to the resin impregnation.

18. The method of claim 14, wherein the silane compounds comprise compounds having a molecular weight of between 32-90, and wherein the compounds having a molecular weight of between 32-90 have an increased tendency to travel into the micro pores of the mica paper relative to larger molecular weight silane compounds.

19. The method of claim 14, wherein said resin is an epoxy resin.