DETAILED DESCRIPTION OF THE INVENTION One embodiment of the present invention pertains to an image release sheet comprising a substrate on which one major surface thereof is a dielectric layer.
A silicone-urea block polymer is on top of the dielectric layer of the substrate and functions as a release coating.
Image release sheets comprise a substrate, preferably a flexible one, on one surface of which is a dielectric layer.
The substrate itself should be electroconductive or it should carry conductive layers on both major surfaces.
The dielectric layer will be on the surface of one of the conductive layers.
Substrates may be chosen from a variety of materials such as cellulose fiber based paper and polyester based plastic film.
If a separate conductive layer is required, this may be composed of polyelectrolytes such as cationic quaternary ammonium compounds or polymers containing a chloride anion or other materials known in the art to be stable at room temperature and at the elevated temperatures (e.
g.
, 230.
degree.
to 270.
degree.
F.
) of the image transfer process.
Dielectric layers on a substrate for use in electrostatic printing processes are well known in the art; see, for example, Neblette's Handbook of Photography and Reprography, C.
B.
Neblette, 7th Edition, 1977.
These layers commonly comprise polymers selected from polyvinylacetate, polyvinylchloride, polyvinylbutyral, and polymethylmethacrylate.
Other ingredients may be chosen from waxes, polyethylene, alkyd resins, nitrocellulose, ethylcellulose, cellulose acetate, epoxy resins, styrene-butadiene polymers, chlorinated rubbers, and polyacrylates.
Performance criteria for dielectric layers are listed in the foregoing Neblette reference.
Such layers are also described in U.
S.
Pat.
Nos.
3,075,859; 3,920,880; 4,201,701; and 4,208,467.
The layers should have a thickness in the range of from 1 to 20 microns and preferably in the range of 5 to 15 microns.
The surface of such dielectric layers are advantageously rough to ensure good transfer of charge during the passage under the stylus bar
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Adhesives and Rubbers 
