Abstract: An elongate electrical conductor is continuously coated with electrostatically charged powder by passing the conductor upwardly through a tube into the upper portion of a container having a charged fluidized bed of the powder in a lower portion thereof. The tube extends upwardly through the bed and the tube height is adjusted relative to the upper surface of the bed to control the thickness of the powder coating. An array of electrodes having associated switches permits application of uniform coatings to conductors having a variety of shapes. Two or more conductors may be uniformly coated from the same fluidized bed in a container having a baffle which divides the upper portion into two or more compartments and spaced apart tubes extend upwardly into the different compartments.

Abstract: An elongate electrical conductor is continuously coated with electrostatically charged powder by passing the conductor upwardly through a tube into the upper portion of a container having a charged fluidized bed of the powder in a lower portion thereof. The tube extends upwardly through the bed and the tube height is adjusted relative to the upper surface of the bed to control the thickness of the powder coating. An array of electrodes having associated switches permits application of uniform coatings to conductors having a variety of shapes. Two or more conductors may be uniformly coated from the same fluidized bed in a container having a baffle which divides the upper portion into two or more compartments and spaced apart tubes extend upwardly into the different compartments.

Abstract: A method is provided for making stable electrocoatable polyimide mixtures having a high water content. A solution of polyimide in a dipolar aprotic solvent is heated in the presence of base resulting in a transitory viscosity decrease. Major amounts of water can thereafter be added to the mixture during its reduced viscosity state to produce a stable aqueous mixture.

Abstract: A continuous method is provided for making polyimide coated conductors, such as wire and metal foil, by continuously passing the conductor into an aqueous plural solvent polyamide acid salt electrocoating bath. Electrodeposition can be effected of polyamide acid having sufficient organic solvent to produce a satisfactory polyimide film by passing the polyamide acid treated conductor through a curing tower. The electrocoating bath can be continuously maintained by use of a semi-permeable membrane allowing for continuous plural solvent and base removal, while makeup aqueous plural solvent polyamide acid salt mixture is continuously introduced into the bath. A polyimide coated aluminum foil useful for making transformer windings is also included.This is a division, of application Ser. No. 497,516 , filed Aug. 15, 1974 now U.S. Pat.

Abstract: A continuous method is provided for making polyimide coated conductors, such as wire and metal foil, by continuously passing the conductor into an aqueous plural solvent polyamide acid salt electrocoating bath. Electrodeposition can be effected of polyamide acid having sufficient organic solvent to produce a satisfactory polyimide film by passing the polyamide acid treated conductor through a curing tower. The electrocoating bath can be continuously maintained by use of a semi-permeable membrane allowing for continuous plural solvent and base removal, while makeup aqueous plural solvent polyamide acid salt mixture is continuously introduced into the bath. A polyimide coated aluminum foil useful for making transformer windings is also included.