FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
COMPLETE SPECIFICATION
(See Section 10)

yRICTION AND^RELEASE COATED POLYIMIDE FILM FOR ELECTRICAL^
INSULATION^^O THE PROCEDO OF MiM^RJFACTURIl'TO TI

PRS Solutions Private Limited, a Company incorporated under the Companies Act, 1956 and having its ofiBce at 63, Bombay Samachar Marg, Mumbai - 400 001 Maharashtra State, India, India.
The following specification particvilarly describeshe nature of this
invention and the manner in which it is to be performed

FIELD OF THE INVENTION:
This invention relates to "Friction and Release Coated Polyimide Film for Electrical Insulation" and the process of manufacturing the same. It consists of 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:
Various types of electrical insulations are available. Copper conductor are to be insulated by varnish. Insulating materials are covered on copper conductor to retain the insulating varnish close to the conductor. Presently plain polyimide film on copper conductor is covered with various other alternatives such as non-adhesive glass cloth tape to retain varnish closd to the conductor which leads to increase in thickness and it is not desirable. 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 present invention avoids use of non adhesive glass cloth tape and also avoids built up of thickness.
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 Polyimide Film on one side with friction coating compound, a special binder having frictional properties and 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:
llllllllllllllllllllllllllllllllllllllllllllllllll ► Release Coating
llllllllllllllllllllllinillllHIIIIIIIIIIIIIIIIII ► Polyimide Film
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIHIIIIIIIIIIIII ► 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 confrol release.
Coating of friction compound or release compound on 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 drying.
The deposition of the release coating in the range of 0.20-0.6 gms per sq. meter. The drying temperature required for this coating is 170 °C.

WE CLAIM:
1. A process for manufacturing a "Friction and Release Coated Polyimide Film for
electrical insulation" comprises the steps of: -
(a) taking polyimide film and coating with "Friction Coating Compound" as defined hereafter, on one side with required depositions preferably of 10 to 20 gms per sq. meters using conventional coating methods and equipments;
(b) following by drying the said firiction coated film in conventional equipment;
(c) coating the other side of the said friction coated film with a "Controlled Release Compound" as defined hereafter, with required deposition preferably of 0.2 to 0.6 gms per sq. meter using conventional coating methods and equipments;
(d) followed by drying/ curing the said fi-iction coated and controlled release coated film 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 like silica.
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 carbamates.
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.
Dated this 8 day of August, 2002