Stock material or miscellaneous articles – Composite – Of metal
Reexamination Certificate
1997-12-01
2001-03-20
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of metal
C428S458000, C428S704000, C428S689000, C428S480000, C428S425800, C428S420000, C428S419000, C428S418000, C428S500000, C428S515000
Reexamination Certificate
active
06203919
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electrically insulating film, particularly an insulating film to be formed on a surface of a conductor substrate, and a method for preparing the same.
Hitherto, the surfaces of conductors have been treated by applying a tape made of a resin on them, or coating them with a resin layer, in order to secure an insulating property of the surfaces of conductors. When a thin insulating film is required, for instance, it is produced by applying a precursor of a resin on the surface of a conductor and baking it with heat as represented by varnish treatment for enamel wires.
With the recent miniaturization of portable electronic appliances, designs of electronic components and motors are directed to their smaller and thinner sizes, and their smaller power consumptions commensurate with the miniaturization of electronic appliances, and thus thinner insulating films are now being required.
However, the insulating film obtained by the above-mentioned surface treatment with a resin tape generally has an insufficient thickness of only not less than dozens of &mgr;m due to restricted durability and workability of the resin tape. On the other hand, varnish-coated films for enamel wire can be reduced in thickness, but, when the thickness is reduced to some &mgr;or less, they easily develop pinholes and lose their insulating property. Similarly, if treated by the method of high speed winding as is often used for production of motor coils, the insulating film loses its insulating property due to possible extension and bending of enamel wire during the winding process, and its withstand voltage per &mgr;drops to about 500 V.
The above phenomenon may be explained that the resin constituting the insulating film is bonded to the surface of metal only mechanically and is easily separated or transferred by an external force.
BRIEF SUMMARY OF THE INVENTION
It is therefore the primary object of the present invention to provide a strong insulating film which secures a satisfactory insulating property even with a film thickness of only some &mgr;and is resistant to stresses imposed during the high speed winding process.
It is another object of the present invention to provide a method for preparing such insulating film with reasonable means.
The present invention provides an electrically insulating film comprising:
a first layer formed on a surface of a conductor substrate of a transition metal, the first layer being comprised of molecules fixed on the surface of the conductor substrate through transition metal-sulfur bonds represented by the formula (1) or chelate bonds selected from the groups represented by the formula (2)
where M represents the transition metal and S represents sulfur, and
a second layer formed on the first layer and comprised of a resin combined with the molecules of the first layer through covalent bonds.
The present invention also provides a method for preparing the insulating film which comprises the steps of:
contacting a compound capable of firmly combining with a conductor through chemical bonds (hereinafter referred to as “anchor compound”) with a substrate, thereby to fix the anchor compound to the surface of the substrate at a high density, and
forming a resin layer on the anchor compound, thereby to bind the resin to the anchor compound through covalent bonds.
Since the insulating film in accordance with the present invention is fixed to the surface of the metal through the chemical bonds, pinholes are most unlikely to develop on the film even when the thickness is reduced, and the resultant film can have a favorable insulating property. Such film can therefore be preferably available as the insulating film for the electronic components and motors. It can also be available as a dielectric film for capacitors.
According to the method in accordance with the present invention, the above-mentioned insulating film can be produced with reasonable means.
While the novel features of the present invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated, along with other object and features thereof, from the following detailed description and examples,
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Mino Norihisa
Ootake Tadashi
Takebe Yasuo
Takezawa Hiroaki
Akin Gump Strauss Hauer & Feld L.L.P.
Boss Wendy
Jones Deborah
Matsushita Electric - Industrial Co., Ltd.
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