Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
1994-09-26
2001-04-10
Morris, Terrel (Department: 1771)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C428S378000, C428S379000, C428S380000, C428S391000, C428S393000, C174S1100SR, C174S11000P, C174S1200SC, C174S1200SR, C528S026000, C528S028000, C528S045000, C525S063000, C525S431000, C525S452000, C525S474000
Reexamination Certificate
active
06214462
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention concerns an enameling lacquer and a process for the manufacture of the lacquer.
The invention is particularly but not exclusively applicable to enameling wire for use in the windings of electric motors or any other electrical components, the wire being applied by an automatic machine, for example.
2. Description of the Prior Art
In the case given of electric motor windings, it is imperative that the windings are as compact as possible and can easily be introduced into an appropriate housing without affecting the insulating properties of the lacquer.
Windings are produced at high speeds; the enameled conductor is subjected to friction and to severe mechanical stress which may damage the insulation and result in irregular winding of the conductor, for example during placement in stator winding slots. There could be serious effects on the insulation properties, service life and efficiency of the component.
A number of solutions have been proposed which are intended to reduce the coefficient of friction of enameled electrical conductors, to provide a smooth surface and to enable them to be wound easily.
A first solution consists in lubricating the exterior of the enameled conductor by coating the surface with a lubricating substance such as paraffin wax, oil, a natural or synthetic wax or polysiloxane. The results are inadequate and irregular.
A second solution consists in providing the conductor with an external layer of polyamide 6—6, trade name NYLON, well known for its slippery qualities. Results show that this process improves smoothness, but the nylon reduces the thermal characteristics of wires with a thermal index of greater than 200° C.
A third solution consists in introducing an internal lubricating agent into the outer layer of a conductor. The polymers most frequently used for this application are aliphatic or aromatic polyamides, aromatic polyamide imides, polyester imides, polyimides, polyvinyl alcohol acetals, mixed aromatic/aliphatic polyamides, polyepoxy compounds and polyphenoxy compounds.
French patent FR-A-2 533 357 indicates how a lacquer can be made which incorporates in the polymer less than 0.3% of a particular form of internal solid lubricant. This technique uses a lubricant which is incompatible with the base polymer. This incompatibility effectively expels the lubricant particles onto the outer surface of the outer layer, improving its slippery qualities. Such a process is very difficult to carry out industrially, however. Mutual incompatibility of the two materials prevents incorporation of a sufficient quantity of lubricant, resulting in frequent irregularities in the conductor which are unacceptable to the user.
The aim of the present invention is to overcome these problems.
SUMMARY OF THE INVENTION
In one aspect, the present invention consists in an enameling lacquer comprising a base first polymer and a copolymer which is compatible with said first polymer and which contains polymeric chains selected from polysiloxanes, fluorinated chains and alkane chains.
In a preferred embodiment, said enameling lacquer also contains a second polymer comprising said chains of said copolymer and forming a polymer blend with said first polymer and said copolymer.
The base first polymer may be selected from any of the polymers currently used in enameling lacquers.
Said lacquer may contain between 0.5% and 20%, in particular between 1% and 10% by weight of copolymer.
It may be advantageous to add said second polymer to the mixture. The presence of the copolymer means that up to 30% by weight of said second polymer can be incorporated into the mixture instead of the previous maximum of 0.3%. The copolymer acts as a compatibilizing agent between the first and second polymers and forms a polymer blend which combines the properties of the two original polymers.
In another aspect, the present invention consists in a process for the synthesis of the above copolymer containing polysiloxane functions and being compatible with a first polymer selected from polyamide imide, polyester, polyester imide, polyester amide-imide, polyamide, polyimide, polyurethane and acetal of polyvinyl alcohol.
The process consists in reacting a functionalized polysiloxane with a diisocyanate whose isocyanate function has been blocked and then grafting the blocked NCO polysiloxane thus obtained onto said first polymer.
The functionalized polysiloxane may be an aminated polysiloxane, for example. The isocyanate function is blocked by reaction with an alcoholic, aromatic or aliphatic reactant such as aliphatic alcohol, phenol, resorcinol, benzyl alcohol, phloroglucinol, etc.
In a further aspect, the present invention consists in an enameled wire comprising at least superficially an enamel obtained by reticulation of the lacquer described above. This enamel may be the base enamel or an overlay on a base enamel or a top layer or an external layer of said base enamel.
In a particularly preferred embodiment, the conducting element is in a thermal class greater than or equal to 200, with a smoothness at least equal to that obtained using an external superficial layer of paraffined polyamide 6—6.
Its overlay is polyamide imide based.
Any of the wires according to the invention can advantageously be furnished with an external lubricating agent selected from paraffin wax, oil, wax, polysiloxane compounds and fluorated chain compounds.
Further features and advantages of the present invention will become apparent from the following description of illustrative, non-limiting embodiments.
REFERENCES:
patent: 3413148 (1968-11-01), Sattler et al.
patent: 3632440 (1972-01-01), Preston
patent: 3674891 (1972-07-01), Wheeler, Jr.
patent: 4130708 (1978-12-01), Friedlander et al.
patent: 4348460 (1982-09-01), Saunders et al.
patent: 4499149 (1985-02-01), Berger
patent: 4652598 (1987-03-01), Edelman
patent: 4659777 (1987-04-01), Riffle et al.
patent: 4693936 (1987-09-01), McGregor et al.
patent: 4769424 (1988-09-01), Takekoshi et al.
patent: 4812518 (1989-03-01), Haubennestel et al.
patent: 2533357 (1982-09-01), None
patent: 1230189 (1971-04-01), None
Andre Raymond
Barraud Jean-Yves
Binder Germaine
Fauvarque Jean-Francois
Le Tiec Pierre-Yves
ALCATEL N.V.
Juska Cheryl
Morris Terrel
Sughrue Mion Zinn Macpeak & Seas, PLLC
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