FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
COMPLETE SPECIFICATION (See Section 10)
"HIGH STRENGTH, THERMALLY CONDUCTING AND ELECTRICALLY INSULATING DUPLEX AND/OR TRIPLEX COMPOSITE FOR ELECTRICAL INSULATION APPLICATION AND THE PROCESS OF MANUFACTURING THE SAME."
PRS Solutions Private Limited, a Company incorporated under the Companies Act, 1956 and having its office at 63, Bombay Samachar Marg, Mumbai - 400 001 Maharashtra State, India.
The following specification particularly describes the nature of this invention and the manner in which it is to be performed

FIELD OF THE INVENTION :
This invention relates to a high strength, thermally conducting and electrically insulating duplex and/or triplex composite comprising of Polyester film, woven glass fabric/s for electrical insulation application and the process of manufacturing the same.
DESCRIPTION OF THE PRIOR- ART :
In the manufacture of electric motors, generators, hermetic motors, transformers, and other electrical devices, it is necessary to use some form of dielectric insulation to separate the internal components thereof. Slot liners which are used as electrical insulation in rotating electrical equipment typically range from 0.175 mm to 0.75 mm in thickness. These insulation products are generally produced in continuous stock rolls which are converted into slit tapes, cut sheets, die cut parts, or the like, as required by the end use.
In thermal class 155 insulations, which are UL recognized for service operating temperatures of up to 155° C, presently a variety of insulating composites either in the form of duplex composite or triplex composites are used as slot insulation for motors and coils. One of the essential component of such composites is Polyester film (PET) and the other component may be non woven Polyester fleece (such as Dacron

of DuPont make), Polyaramide Paper (such as Nomex made by DuPont) or Ceramic paper of various thicknesses.
The most widely used composite is known as "DMD", ( Dacron - Mylar - Dacron ) and is formed from non-woven polyester fabric which is bonded to opposite sides of polyester film. They tend to gradually and progressively de-composite while in service, if flexed improperly, or if the adhesive bond is defective. This delamination of DMD may become worst by recurring temperature fluctuations, accompanied by ambient moisture which results in freezing and thawing cycles there by deteriorating the DMD composite. Composites of Polyester film and Polyaramide paper are also very widely used as slot insulation, however apart from being very costly they do not help in dissipation of heat generated. Very hygroscopic nature of Polyaramide paper makes these composites susceptible to reduction in insulation properties particularly in highly humid ambient conditions. Composites of Polyester film and Ceramic papers are good conductor of heat and helps in dissipation of heat faster, however Ceramic paper being fragile in nature these composites lack the mechanical strength and may develop voids when flexed improperly.
INVENTION :
This invention describes an electrically insulating, thermally conducting, mechanically strong composite for use as slot insulation of Motors, Alternators, Generators, Coils etc. for upto temperature class 155°C. The composite is made using

an unique combination of woven fabric made of inorganic substance with film of organic nature. While the organic component is Polyester film which imparts the basic electrical insulation, the inorganic component is a woven Glass fabric which acts as re-enforcement thereby providing additional mechanical properties such as high Tensile strength, excellent resistance to tear initiation and tear propagation in both directions. The said glass fabric is made out of E Class glass yarn. The Glass cloth weave being open in nature permits heat to conduct through it and consequently acts as a thermally conducting layer there by providing the most desirable combination of properties in any electrical insulation composite which is electrically insulating but thermally conducting. High thermal conductivity promotes cooler running equipment, leading to longer insulation life, better reliability and more efficient use of power. Additionally, the woven glass fabric acts as varnish receptive surface because of the weave structure thereby ensuring that the varnish flowing into the coils is absorbed and retained by the insulating composite, thus providing the copper conductor with the requisite environmental protection. This composite is non-hygroscopic and exhibit low moisture absorption, thus reducing need for extended drying cycles prior to varnishing or encapsulation.
SUMMARY OF THE INVENTION :
The present invention describes composite prepared by laminating woven Glass fabric on one or both sides of Polyester film using two-component polyurethane adhesive. The thickness of the woven Glass fabric may be used as per the needs of the final

composite thickness ranging from 2.0 to 10 mil and the same applies for Polyester film where the thickness ranges from 1.0 mil to 14.0 mil & higher. The high temperature resistant laminating adhesive was used after suitably formulating various ingredients commonly available in market, based on polyurethane and isocyanate, keeping a deposition preferably ranging from 10 to 30 grams./sq. meter however lower or higher deposition can be used. The coating of this formulated adhesive was done using conventional coating equipments.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
DUPLEX COMPOSITE :
Following are the steps involved in the manufacture of duplex composite:
The Polyester film is coated with polyurethane adhesive which is dried on a conventional coating machine and then laminated to woven Glass fabric under pressure. The coating, drying and lamination is done as per conventional methods. The deposition of the adhesive preferably range from 10 to 30 grams./sq. meter. However lower or higher deposition can be used.
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TRIPLEX COMPOSITE
Following are the steps involved in the manufacture of triplex composite:
The film side of the duplex composite as described above is again coated with polyurethane adhesive which is dried on a conventional coating machine and then laminated to woven Glass fabric under pressure. The coating, drying and lamination is done as per conventional methods. The deposition of the adhesive preferably range from 10 to 30 grams./sq. meter. However lower or higher deposition can be used

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Glass cloth Laminating Adhesive Polyester Film Laminating Adhesive Glass cloth

The final product was then slit to size as required for the intended application using conventional slitting machines.

WE CLAIM :
1. A high strength, thermally conducting and electrically insulating duplex and/or triplex composite for electrical insulation application and the process of manufacturing the same comprising of woven glass fabric and Polyester film as per the following steps:-
(i) Coating the Polyester film with Polyurethane adhesive on one side with a required deposition preferably ranging from 10 to 30 gm/m<2, however lower or higher deposition can be used, and using conventional coating methods followed by drying in conventional equipments and laminating to Woven Glass Fabric to get the duplex composite;
(ii) Coating the Polyester film side of the said duplex composite with Polyurethane adhesive having required deposition preferably ranging from 10 to 30 gm/m2, however lower or higher deposition can be used, and using conventional coating method followed by drying in conventional equipments and laminating to another Woven Glass Fabric to get the triplex composite.
2. A high strength, thermally conducting and electrically insulating duplex and/or triplex composite for electrical insulation application and the process of manufacturing the same as claimed in Claim 1, wherein the woven glass fabric is

made out of 'E' class glass yarn and is having a plain weave where the thickness of woven glass fabric may be 2.0 to 10.0 mil.
3. A high strength, thermally conducting and electrically insulating duplex and/or triplex composite for electrical insulation application and the process of manufacturing the same as claimed in Claim 1, wherein Polyester film is transparent or white with thickness may be 1.0 to 14.0 mil.
4. A high strength, thermally conducting and electrically insulating duplex and/or triplex composite for electrical insulation application and the process of manufacturing the same as claimed in Claim 1, where the adhesive used for bonding the woven glass fabric and Polyester film was two component Polyurethane adhesive.
5. A high strength, thermally conducting and electrically insulating duplex and/or
triplex composite comprising of woven glass fabric and Polyester film for electrical
insulation application is obtained by the process as claimed in claims 1 to 4 above.
Dated this 21st day of December, 2006
(Bharat S. Shah) Duly Constituted Attorney

ABSTRACT
A high strength, thermally conducting and electrically insulating duplex and/or triplex composite for electrical insulation application and the process of manufacturing the same comprising of woven glass fabric and Polyester film by (i) Coating the Polyester film with Polyurethane adhesive on one side with a required deposition preferably ranging from 10 to 30 gm/m<2, however lower or higher deposition can be used, and using conventional coating methods followed by drying in conventional equipments and laminating to Woven Glass Fabric to get the duplex composite; (ii) Coating the Polyester film side of the said duplex composite with Polyurethane adhesive having required deposition preferably ranging from 10 to 30 gm/m2, however lower or higher deposition can be used, and using conventional coating method followed by drying in conventional equipments and laminating to another Woven Glass Fabric to get the triplex composite.
(Bharat S. Shah)
Duly Constituted Attorney