MANNA PRAPHULLA KUMAR (IN)
SHROFF PRADIP HIRALAL (IN)
MANNA PRAPHULLA KUMAR (IN)
SHROFF PRADIP HIRALAL (IN)
| EP0441321A2 | 1991-08-14 | |||
| EP0489429A1 | 1992-06-10 | |||
| US4543295A | 1985-09-24 | |||
| EP0605112A2 | 1994-07-06 |
| 1. | A process of manufacturing"Friction and Release Coated Polyimide Film for electrical insulation"and the process of manufacturing the same comprising of polyimide film and coating with"Friction Coating Compound"on one side with a desired depositions preferably of 10 to 20 gms per sq. meter, using conventional coating methods and equipment ; followed by drying/curing in conventional equipments and coating with a "Controlled Release Compound"on the other side of the film with a desired preferably deposition of 0.2 to 0.6 gms per sq. meter using the conventional coating methods and equipments followed by drying/using in conventional equipments. |
| 2. | A process for manufacturing"Friction and Release Coated Polyimide Film for electrical insulation"as claimed in Claim 1, wherein the"Friction Coating Compound"is based on flexible binders like silicone, polyurethane, polyesters or epoxy resin followed by mixing with inorganic materials. |
| 3. | A process for manufacturing"Friction and Release Coated Polyimide Film for electrical insulation"as claimed in Claim 1, wherein the Controlled Release Coating is based on silicones or organic carbomades. |
| 4. | A process of manufacturing"Friction and Release Coated Polyimide Film for electrical insulation"as claimed in Claim 1,2, & 3 above by which"Friction and Release Coated Polyimide Film"is obtained. |
FIELD OF THE INVENTION: This invention relates to manufacture of"Friction and Release Coated Polyimide Film for Electrical Insulation"and the process of manufacturing the same. It consists polyimide film coated with a special friction coating on one side and controlled release coating on the other side of the polyimide film. Friction coating gives the polyimide film higher varnish absorption properties and the release coating helps in the ease of application.
DESCRIPTION OF THE PRIOR ART: Insulating materials are covered on copper condutor to retain the insulating varnish close to the conductor. Presently plain polyimide film on copper conductor is covered with various other alternatives to retain varnish close to the conductor and thereby building up the thickness. Presently, Teflon coated glass cloth or glass cloth non-adhesive tape are used as covering materials.
INVENTION : In high voltage coils where Vapour Pressure Impregnation is mandatory, it is highly desirable that there are no air gaps between the copper conductor and the polyimide film and the coil/conductor is tightly bound by the resin. The newly developed insulating material has a special friction coating on one side which ensure that no air gaps are left between the copper conductor and polyimide film giving good electrical properties, mechanical strength and environmental protection.
The product developed is a Class H material (180 ° C) SUMMARY OF THE INVENTION: The process for manufacturing Friction and Release Coated Polyimide Film for Electrical Insulation comprises of coating with friction coating compound, a special binder having frictional properties on one side, the other side being coated with control release coating, a special release material in order to ease out process of applications.
Following are the steps involved in the manufacture of Friction and Release Coated Polyimide Film for Electrical Insulation.
DESCRIPTION OF THE PREFERRED EMBODIMENTS : ////////////////FILM llllllllllllllllllllllllll Release Coating llllllllllllllll FILM llllllllllllllllllllllllll Polyimide Film
FIILM Specially Formulated Friction Coating The friction coating compound is prepared based on Flexible binders like silicone, polyurethane, polyesters or epoxy resin followed by mixing with inorganic materials like slilica which gives frictional properties. Silica used in this formulation is of special grade and even after grinding. with resin it retains its roughness which is responsible for friction.
Polyimide film used in this invention is of different thickness ranging from 0.025 mm to 0.075 mm thickness.
The release coating is based on silicones or organic carbamates. It is specially formulated to give the control release.
Coating of friction compound or release compound of polyimide film is carried out by conventional coating techniques like reverse roll coating or knife over roll coating.
The grammage of the friction coating compound varies from 10 to 20 gms per sq. meter depending upon the need and it requires a temperature of 190 ° C for curing.
The deposition of the release coating in the range of 0.20-0. 6 gms per sq. meter. The curing temperature requires for this coating is 170 ° C.