Perfluoroether release coatings for organic photoreceptors

This invention is a photoconductive element comprising an electroconductive substrate, a photoconductive layer on a surface of the electroconductive substrate, and a release layer over the photoconductive layer. The release layer comprises a fluoroether polymer which is the reaction product of components comprising: A) a di-functional perfluoroether, B) a diisocyanate, C) an amino functional silane, and D) optionally, a diol chain extender.

FIELD OF THE INVENTION 
The present invention relates to a photoreceptor element which is capable 
of transferring toner images to a receptor. More specifically, this 
invention relates to a release coating for the photoreceptor element. 
BACKGROUND OF THE INVENTION 
Electrophotography forms the technical basis for various well known imaging 
processes, including photocopying and laser printing. The basic 
electrophotographic process involves placing a uniform electrostatic 
charge on a photoreceptor element; imagewise exposing the photoreceptor 
element to light, thereby dissipating the charge in the exposed areas; 
developing the resulting electrostatic latent image with a toner; and 
transferring the toner image from the photoreceptor element to a final 
substrate, such as paper or film, either by direct transfer or via an 
intermediate transfer material. 
The structure of photoreceptor element may be a flat plate, a rotatable 
drum, or a continuous belt which is supported and circulated by rollers. 
All photoreceptor elements have a photoconductive layer which conducts 
electric current only when it is being exposed to light. The 
photoconductive layer is generally affixed to an electroconductive 
support. The surface of the photoconductor is either negatively or 
positively charged such that when light strikes the photoconductive layer, 
charge is conducted through the photoconductor in that region to 
neutralize the surface potential in the illuminated region. An optional 
barrier layer may be used over the photoconductive layer to protect the 
photoconductive layer and extend the service life of the photoconductive 
layer. 
Typically, a positively charged toner is attracted to those areas of the 
photoreceptor element which retain a charge after the imagewise exposure, 
thereby forming a toner image which corresponds to the electrostatic 
latent image. The toner need not be positively charged. Some toners are 
attracted to the areas of the photoconductor element where the charge has 
been dissipated. The toner may be either a powdered material comprising a 
blend of polymer and colored particulates, typically carbon, or a liquid 
material of finely divided solids dispersed in an insulating liquid. 
Liquid toners are often preferable because they are capable of giving 
higher resolution images. 
The toner image may be transferred to the substrate or an intermediate 
carrier by means of heat, pressure, a combination of heat and pressure, or 
electrostatic assist. A common problem that arises at this stage of 
electrophotographic imaging is poor transfer from the photoconductor to 
the receptor or intermediate carrier. Poor transfer may be manifested by 
low transfer efficiency and low image resolution. Low transfer efficiency 
results in images that are light and/or speckled. Low image resolution 
results in images that are fuzzy. These transfer problems may be 
alleviated by the use of a release coating. 
The release layer is applied over the photoconductive layer or over the 
barrier layer if a barrier layer is being used. The release layer must 
adhere well to the photoconductive or barrier layer without the need for 
adhesives. Moreover, the release layer must not significantly interfere 
with the charge transport characteristics of the photoconductor 
construction. 
Typical release coatings known in the electrophotographic arts include 
silicone polymers such as those disclosed in U.S. Pat. No. 4,600,673. 
Conventional silicone polymer release materials tend to swell 
significantly in the hydrocarbon solvents which are used as carrier 
liquids in electrophotography. Swollen polymers generally have reduced 
toughness, and siloxanes, which typically do not have good tensile 
properties, are very easily scratched when swollen. 
Solvent resistance may be improved by adding fillers to or by cross-linking 
the polymer. However, cross-linked or filled systems tend to have 
increased the surface energy causing a decreased release performance. 
U.S. Pat. No. 4,996,125 discloses the use of a perfluoroalkyl polyether and 
its derivatives as a lubricating layer. This patent includes an Example 
having a perfluoroether-urethane polymer lubricating layer on a 
electrophotographic photoreceptor. Images were made using a FX 4300 copier 
(Fuji Xerox Co., Ltd.), which is a copier that uses dry toner. However, 
when the present inventors tested similar release coatings with a liquid 
toner system, they found that such perfluoroether-urethane polymer release 
coats had poor resistance to liquid toner and a relatively high peel 
force. 
Due to an increasing demand for more imaging cycles per photoreceptor 
element, a desire remains for a durable release layer with good release 
properties. Specifically, the release layer should be mechanically durable 
as to withstand abrasion of the various rollers and scrapers which contact 
the photoreceptor element. The release layer must also be resistant to the 
toner carrier liquids. 
SUMMARY OF THE INVENTION 
The present invention provides a photoreceptor element comprising an 
electroconductive substrate, a photoconductor layer, and a release layer 
which displays good release properties, as well as good durability and 
resistance to toner carrier liquids. The release layer comprises a 
perfluoroether urethane which includes silicon atoms (Si), via a silane 
group. 
The release layer comprises a perfluoroether urethane which is the reaction 
product of a di-functional perfluoroether, a diisocyanate, an amino 
functional silane, and, optionally, a diol chain extender. Preferably, the 
perfluoroether urethane has the following structure: 
EQU C--B--A--B--D!.sub.x --B--A!.sub.y --B--C, 
wherein A, B, C, and D are defined by the perfluoroether, the diisocyanate, 
the amino functional silane, and the diol chain extender, respectively; x 
is an integer from 0 to 10, and y is an integer from 1 to 10. Use of the 
diol chain extender, by having x greater than 1, is optional but preferred 
because it increases the resistance of the release layer to toner carrier 
liquids. 
This release layer on an organic photoconductor has good toner release 
performance and good resistance to wiping, swelling and crazing with a 
toner carrier liquid. The perfluoroether urethane release coating can be 
used as a durable overcoat for an organic photoconductor used with liquid 
toners. 
DETAILED DESCRIPTION OF THE INVENTION 
The photoreceptor element of this invention comprises an electroconductive 
substrate which supports at least a photoconductor layer and a release 
layer. The photoconductors of this invention may be of a drum type 
construction, a belt construction, a flat plate, or any other construction 
known in the art. 
Electroconductive substrates for photoconductive systems are well known in 
the art and are two general classes: (a) self-supporting layers or blocks 
of conducting metals, or other highly conducting materials; and (b) 
insulating materials such as polymer sheets, glass, or paper, to which a 
thin conductive coating, such as vapor coated aluminum, has been applied 
(e.g., aluminized polyethylene terephthalate). 
The photoconductive layer can be any type known in the art, including an 
inorganic photoconductor material in particulate form dispersed in a 
binder or, more preferably, an organic photoconductor material. The 
thickness of the photoconductor layer is dependent on the material used, 
but is typically in the range of 5 to 150 .mu.m. 
Photoreceptor elements having organic photoconductor material are discussed 
in Borsenberger and Weiss, Photoreceptors: Organic Photoconductors, Ch. 9 
Handbook of Imaging Materials, ed. Arthur S. Diamond, Marcel Dekker, Inc. 
1991. When an organic photoconductor material is used, the photoconductive 
layer can be a bilayer construction consisting of a charge generating 
layer and a charge transport layer. The charge generating layer is 
typically about 0.01 to 20 .mu.m thick and includes a material which is 
capable of absorbing light to generate charge carriers, such as a dyestuff 
or pigment. The charge transport layer is typically 10-20 .mu.m thick and 
includes a material capable of transporting the generated charge carriers, 
such as poly-N-vinylcarbazoles or derivatives of 
bis-(benzocarbazole)-phenylmethane in a suitable binder. 
In bilayer organic photoconductor layers in photoreceptor elements, the 
charge generation layer is typically located between the conductive 
substrate and the charge transport layer. Such a photoreceptor element is 
usually formed by coating the conductive substrate with a thin coating of 
a charge generation layer, overcoated by a relatively thick coating of a 
charge transport layer. During operation, the surface of the photoreceptor 
element is negatively charged. Upon imaging, in the light-struck areas, 
hole/electron pairs are formed at or near the charge generation 
layer/charge transport layer interface. Electrons migrate through the 
charge generation layer to the conductive substrate while holes migrate 
through the charge transport layer to neutralize the negative charge on 
the surface. In this way, charge is neutralized in the light-struck areas. 
Alternatively, an inverted bilayer system may be used. Photoconductor 
elements having an inverted bilayer organic photoconductor material 
require positive charging which results in less deterioration of the 
photoreceptor surface. In an inverted bilayer system, the conductive 
substrate is coated with a relatively thick coating (preferably, 
5-20.mu.m) of a charge transport layer, overcoated with a relatively thin 
(preferably, 0.01 to 5 .mu.m) coating of a charge generation layer. During 
operation, the surface of the photo-receptor is positively charged. Upon 
imaging, in the light-struck areas, hole/electron pairs are formed at or 
near the charge generation layer/charge transport layer interface. 
Electrons migrate through the charge generation layer to neutralize the 
positive charge on the surface while holes migrate through the charge 
transport layer to the conductive substrate. In this way, charge is again 
neutralized in the light-struck areas. 
Single layer photoconductive layers are also common. In a single-layer 
construction, a mixture of charge generation and charge transport 
materials are incorporated into one layer. This layer has both charge 
generating and charge transport capabilities. Examples of single-layer 
organic photoconductive layers are described in U.S. Pat. Nos. 4,853,310; 
5,087,540; and 3,816,118. A disadvantage of single layer constructions is 
that they tend suffer fatigue on repeated cycling and cannot be used in 
high speed systems. 
Suitable charge generating materials for use in a single layer 
photoconductor and/or the charge generating layer of a bilayer 
photoconductor include azo pigments, perylene pigments, phthalocyanine 
pigments, squaraine pigments, and two phase aggregate materials. The two 
phase aggregate materials contain a light sensitive filamentary 
crystalline phase dispersed in an amorphous matrix. 
The charge transport material transports the charge (holes or electrons) 
from the site of generation through the bulk of the film. Charge transport 
materials are typically either molecularly doped polymers or active 
transport polymers. Suitable charge transport materials include enamines, 
hydrazones, oxadiazoles, oxazoles, pyrazolines, triarylamines, and 
triarylmethanes. A suitable active transport polymer is polyvinyl 
carbazole. Especially preferred transport materials are polymers such as 
poly(N-vinyl carbazole) and acceptor doped poly(N-vinylcarbazole). 
Additional materials are disclosed in Borsenberger and Weiss, 
Photoreceptors: Organic Photoconductors, Ch. 9 Handbook of Imaging 
Materials, ed. Arthur S. Diamond, Marcel Dekker, Inc. 1991. 
Suitable binder resins for the organic photoconductor materials include 
polyesters, polyvinyl acetate, polyvinyl chloride, polyvinylidene 
chloride, polycarbonates, polyvinyl butyral, polyvinyl acetoacetal, 
polyvinyl formal, polyacrylonitrile, polymethyl methacrylate, 
polyacrylates, polyvinyl carbazoles, copolymers of monomers used in the 
above-mentioned polymers, vinyl chloride/vinyl acetate/vinyl alcohol 
terpolymers, vinyl chloride/vinyl acetate/maleic acid terpolymers, 
ethylene/vinyl acetate copolymers, vinyl chloride/vinylidene chloride 
copolymers, cellulose polymers and mixtures thereof. Suitable solvents 
used in coating the organic photoconductor materials include nitrobenzene, 
chlorobenzene, dichlorobenzene, trichloroethylene, tetrahydrofuran, and 
the like. 
Inorganic photoconductors such as, for example, zinc oxide, titanium 
dioxide, cadmium sulfide, and antimony sulfide, dispersed in an insulating 
binder are well known in the art and may be used in any of their 
conventional versions with the addition of sensitizing dyes where 
required. The preferred binders are resinous materials, including, but not 
limited to, styrenebutadiene copolymers, modified acrylic polymers, vinyl 
acetate polymers, styrene-alkyd resins, soya-alkyl resins, 
polyvinylchloride, polyvinylidene chloride, acrylonitrile, polycarbonate, 
polyacrylic and methacrylic esters, polystyrene, polyesters, and 
combinations thereof. 
The release layer of this invention comprises a perfluorourethane 
preferably having the following structure: 
EQU C--B--A--B--D!.sub.x --B--A!.sub.y --B--C, 
wherein A is derived from a di-functional perfluoroether, B is derived from 
a diisocyanate, C is derived from an amino functional silane, D is derived 
from a diol chain extender, x is an integer from 0 to 10, and y is an 
integer from 1 to 10. Preferably, x is 1 to 5 and y is 1 to 3. Preferably 
A has the formula 
EQU --O--R.sub.a --(R.sub.F).sub.m --R.sub.a --O-- 
wherein each R.sub.a is a divalent linking group, each R.sub.F 
independently is perfluorinated oxyalkylene group from 1 to 5, more 
preferably 1 to 2 carbon atoms, and m is an integer of from 5 to 50. More 
preferably A has the formula 
EQU --O--CH.sub.2 (CH.sub.2).sub.p CF.sub.2 (OCF.sub.2).sub.m (OCF.sub.2 
CF.sub.2).sub.n OCF.sub.2 --O-- 
wherein m is an integer of from 5 to 25; n, is an integer of from 5 to 25; 
and p is an integer of from 0 to 3. 
Preferably, B has the formula 
##STR1## 
wherein R.sub.b is a divalent organic linking group. Preferably, C has the 
formula 
##STR2## 
wherein, R.sub.1, R.sub.2, and R.sub.3 are independently hydrogen, alkyl 
groups, preferably of 1 to 5 carbon atoms, aryl groups, and alkoxy groups, 
preferably of 1 to 5 carbon atoms, provided that at least one of R.sub.1, 
R.sub.2, and R.sub.3, is a hydrogen or, more preferably an alkoxy group; 
R is an alkylene group, alkenylene group, or arylene group; 
R.sub.4 is a hydrogen, alkyl groups of 1 to 5 carbon atoms, or an aryl 
group, and 
d is an integer up to 10, preferably 1 to 5. 
Preferably, D has the formula 
EQU --O--R.sub.d --O-- 
wherein R.sub.d is a divalent organic linking group. 
The inventive release layer may be formed by initially reacting a 
di-functional perfluoroether, such as a perfluoroether diol with a 
diisocyanate. An amino silane is then added to the mixture and the 
reaction is completed. Preferably, the perfluoroether diol and 
diisocyanate are further reacted with a diol chain extender before the 
addition of the silane. Preferably, the equivalent ratios of the reactants 
are 1 equivalent of di-functional perfluoroether:2 equivalents of 
diisocyanate: 1.5-1.9 equivalents of aminofunctional silane:0.1-0.5 
equivalents of diol chain extender. 
Suitable perfluoroether diols include, but are not limited to, those having 
the formula: 
EQU HO--R.sub.a --(R.sub.F).sub.m --R.sub.a --OH 
wherein R.sub.a is a divalent linking group, preferably a substituted or 
unsubstituted alkylene group of 1 to 5 carbon atoms or a carbon to oxygen 
bond, each R.sub.F independently is perfluorinated oxyalkylene group from 
1 to 5, more preferably 1 to 2, carbon atoms, m is an integer of from 5 to 
50. One preferred class of perfluoroether diols have the formula 
EQU HO--CH.sub.2 (CH.sub.2).sub.p CF.sub.2 (OCF.sub.2).sub.m (OCF.sub.2 
CF.sub.2).sub.n OCF.sub.2 --OH 
wherein m is an integer of from 5 to 25; n, is an integer of from 5 to 25; 
and p is an integer of from 0 to 3. 
Any known diisocyante may be used. Suitable diisocyanates include but are 
not limited to 1,3-bis(1-isocyanato-1-methylethyl)-benzene; 
1,12-diisocyanato-dodecane; 4,4'-methylenebis(cyclohexyl isocyanate); 
4,4'-methylenebis(phenyl isocyanate); 4,4'-methylenebis(2,6-diethylphenyl 
isocyanate); 3,3'-dimethoxy-4,4'-biphenylenediisocyanate; 
3,3'-dimethyldiphenylmethane-4,4'-diisocyanate; 1,4-phenylene 
diisocyanate; 1,4-diisocyanatobutane; 1,3-phenylenediisocyanate; m-xylene 
diisocyanate; 1,8-diisocyanatooctane; trans-1,4-cyclohexylene 
diisocyanate; 1,6-diisocyanatohexane; toluene 2,6-diiscyanate; and 
1,5-diisocyanato-2-methylpentane. An especially preferred diisocyanate is 
2,4-toluenediisocyanate. 
Suitable silanes include those having the formula. 
##STR3## 
wherein, R.sub.1, R.sub.2, and R.sub.3 are independently hydrogen, alkyl 
groups, preferably of 1 to 5 carbon atoms, aryl groups, and alkoxy groups, 
preferably of 1 to 5 carbon atoms, provided that at least one of R.sub.1, 
R.sub.2, and R.sub.3, is a hydrogen or, more preferably an alkoxy group; 
R is an alkylene group, alkenylene group or arylene group; 
R.sub.4 is a hydrogen, an alkyl group of 1 to 5 carbon atoms, or an aryl 
group; 
d is an integer up to 10, preferably 1 to 5. 
Trialkoxysilyl-aminoalkanes are preferred. An especially preferred silane 
is 1 -triethoxysilyl-3-N-methylaminopropane. 
Suitable chain extending diols include alkylene diols, arylene diols, 
alkenylene diols. Alkylene diols of 1 to 10 carbon atoms are preferred. 
The above release layer is mechanically durable and very resistant to 
hydrocarbons which typically serve as toner carrier liquids. Preferably 
the thickness of the release layer is at least 0.1 .mu.m. The maximum 
thickness is dependent on the photoconductor material, but preferably is 
0.3 to 3 .mu.m, more preferably 0.5 to 1.0 .mu.m. 
Optionally, the photoreceptor element of this invention may further 
comprise a barrier layer between the photoconductor layer and the release 
layer. The barrier layer protects the photoconductor layer from the toner 
carrier liquid and other compounds which might damage the photoconductor. 
The barrier layer also protects the photoconductive layer from damage that 
could occur from charging the photoreceptor element with a high voltage 
corona. The barrier layer, like the release layer, must not significantly 
interfere with the charge dissipation characteristics of the photoreceptor 
element and must adhere well to the photoconductive layer and the release 
layer without the need for adhesives. The barrier layer may be any known 
barrier layer, such as those disclosed in U.S. Pat. Nos. 4,439,509; 
4,606,934; 4,595,602; 4,923,775; 5,124,220; 4,565,760; and WO95/02853. 
Other layers, such as primer layers, substrate blocking layers, etc. as are 
known in the art may also be included in the photoreceptor element. 
As is well understood in this area, substitution is not only tolerated, but 
is often advisable and substitution is anticipated on the compounds used 
in the present invention. As a means of simplifying the discussion and 
recitation of certain substituent groups, the terms "group" and "moiety" 
are used to differentiate between those chemical species that may be 
substituted and those which may not be so substituted. Thus, when the term 
"group," or "aryl group," is used to describe a substituent, that 
substituent includes the use of additional substituents beyond the literal 
definition of the basic group. Where the term "moiety" is used to describe 
a substituent, only the unsubstituted group is intended to be included. 
For example, the phrase, "alkyl group" is intended to include not only 
pure hydrocarbon alkyl chains, such as methyl, ethyl, propyl, t-butyl, 
cyclohexyl, iso-octyl, octadecyl and the like, but also alkyl chains 
bearing substituents known in the art, such as hydroxyl, alkoxy, phenyl, 
halogen atoms (F, Cl, Br, and I), cyano, nitro, amino, carboxy, etc. For 
example, alkyl group includes ether groups (e.g., CH.sub.3 --CH.sub.2 
--CH.sub.2 --O--CH.sub.2 --), haloalkyls, nitroalkyls, carboxyalkyls, 
hydroxyalkyls, sulfoalkyls, etc. On the other hand, the phrase "alkyl 
moiety" is limited to the inclusion of only pure hydrocarbon alkyl chains, 
such as methyl, ethyl, propyl, t-butyl, cyclohexyl, iso-octyl, octadecyl, 
and the like. Substituents that react with active ingredients, such as 
very strongly electrophilic or oxidizing substituents, would of course be 
excluded by the ordinarily skilled artisan as not being inert or harmless. 
By alkylene group is meant an alkyl group with two points of attachment 
formed by replacement of two hydrogen atoms with bonds (e.g. methylene 
from methane). By alkenylene group is meant an alkene group with two 
points of attachment formed by replacement of two hydrogen atoms with 
bonds (e.g. butenylene from butene). By arylene group is meant an aromatic 
group with two points of attachment formed by replacement of two hydrogen 
atoms with bonds (e.g. phenylene from benzene). By oxyalkylene group is 
meant a chain of atoms comprising alkylene groups and oxygen atoms. 
Reasonable modifications and variations are possible from the foregoing 
disclosure without departing from either the spirit or scope of the 
invention as defined by the claims. Objects and advantages of this 
invention will now be illustrated by the following examples, but the 
particular materials and amounts thereof recited in these examples, as 
well as other conditions and details, should not be construed to unduly 
limit this invention.

EXAMPLES 
All materials used in the following examples are readily available from 
standard commercial sources, such as Aldrich Chemical Co. Milwaukee, Wis., 
unless otherwise specified. All percentages are by weight unless otherwise 
indicated. The following additional terms and materials were used. 
FC-113 is a fluorochemical solvent available from 3M Company, St. Paul, 
Minn. 
Daracure 1173 catalyst is a UV photoinitiator and is available from Merck. 
Desoto 952 is a UV-curable multifunctional acrylate monomer and is 
available from Desoto Corporation, Ill. 
Dow Corning 176 is a tin catalyst and is available from Dow Corning Corp. 
1-Triethoxysilyl-3-N-methylaminopropane has the formula shown below and is 
the precursor for the C portion of the compounds described herein. It was 
obtained from Hul Company as catalog item No. M8620. 
##STR4## 
1,3-Butanediol and has the formula shown below and is the precursor for the 
D portion of the compounds described herein. 
##STR5## 
The perfluoroether diol used has a molecular weight of 1850 and has the 
structure shown below: 
EQU HO--CH.sub.2 CF.sub.2 (OCF.sub.2).sub.15 (OCF.sub.2 CF.sub.2).sub.13 
OCF.sub.2 --OH. 
The perfluoroether diester used has a molecular weight of 2000 and has the 
structure shown below: 
EQU C.sub.2 H.sub.5 OOCCH.sub.2 CF.sub.2 (OCF.sub.2).sub.15 (OCF.sub.2 
CF.sub.2).sub.13 OCF.sub.2 COOC.sub.2 H.sub.5. 
2,4-Toluenediisocyanate has the formula shown below: 
##STR6## 
Sample 1 release coat formulation as disclosed in U.S. Pat. No. 4,600,673 
based on Syl-Off.TM. 23 from Dow Corning. 
Synthesis of Comparative Fluoro-Urethane (Sample 2) 
As a comparative example, formulations incorporating an acrylate terminated 
fluorochemical polymer into a conventional UV-curable acrylate polymer 
were investigated. 
The following is a general procedure to prepare these UV-cured samples. A 
5% by weight solution of Desoto 952 (1.5 g), fluoro-modified acrylate 
urethane (3.5 g,), and 95 g of isopropyl alcohol was prepared. Daracure 
1173 catalyst (0.1 g) was then added to this stock solution. The solution 
was coated with a #8 Meyer bar onto a piece of 3M Digital Matchprint.TM. 
organic photoreceptor substrate (without its standard silicone overcoat). 
The coated samples were cured by passing at a speed of 100 ft/min (30.5 
m/min) under nitrogen using medium pressure mercury lamps. 
Synthesis of Compound B--A--B (Sample 3--Comparative) 
A solution of 20 g of fluorochemical solvent FC-113, 8.27 g of 
perfluoroether diol, 1.6 g of 2,4-toluenediisocyanate and one drop (0.02 
g) of dibutyl tin dilaurate was mixed and stirred overnight (ca. 15 hours) 
at room temperature to form Compound B--A--B as a 33% solids solution. It 
was saved for use in subsequent coatings. 
##STR7## 
Synthesis of Compound--(A--B).sub.x --(Sample 4--Comparative) 
A solution of 40 g of fluorochemical solvent FC-113, 16.54 g of 
perfluoroether diol, 1.6 g of 2,4-toluenediisocyanate and one drop (0.02 
g) of dibutyltin dilaurate was mixed and stirred overnight (ca. 15 hours) 
at room temperature to form polymer Compound--(A--B).sub.x -- as a 31.2% 
solids solution. IR spectral analysis of the solution indicated the 
absence of unreacted isocyanate groups. The solution was saved for use in 
subsequent coatings. 
##STR8## 
Synthesis of Compound C--A'--C (Sample 5--Comparative) 
A solution of 20 g of perfluoroether diester dissolved in 20 g of 
fluorochemical solvent FC-113 was slowly added to a solution of 3.86 g (2 
equivalents) of 1-triethoxysilyl-3-N-methylaminopropane dissolved in 20 g 
of FC-113. The addition was carried out at room temperature. The reaction 
mixture was allowed to stir overnight at room temperature to form Compound 
C--A'--C as a 37.5% solution. IR spectral analysis was used to determine 
the progress of the reaction and confirmed the total replacement of the 
ester group (.about.1800 cm.sup.-1) by the amide group (.about.1715 
cm.sup.-1). The solution was saved for use in subsequent coatings. 
##STR9## 
Synthesis of Perfluoroether Compound C--B--A--B--C (Sample 6) 
A solution of 15 g of fluorochemical solvent FC-113, 5.0 g of 
perfluoroether diol, 0.89 g of2,4-toluenediisocyanate, and one drop (0.02 
g) of dibutyltin dilaurate was prepared and stirred overnight (ca. 15 
hours) at room temperature. A solution of, 0.97 g of 
1-triethoxysilyl-3-N-methylaminopropane in 5.0 g of FC-113 was added to 
the solution. Stirring was continued for 1 hour. IR spectral analysis of 
the solution confirmed the absence of any unreacted isocyanate groups. The 
solution (25.54% solids) was saved for use in subsequent coatings. 
##STR10## 
Synthesis of Perfluoroether Compound C--B--A--B--D!.sub.X --B--A--B--C 
(Sample 7) 
As noted above, addition of 1,3-butanediol results in the formation of a 
chain-extended oligimer. A chain-extended oligomer was prepared with 
x=1-10. 
A solution of 20 g of fluorochemical solvent FC- 113, 8.27 g of 
perfluoroether diol, 1.6 g of 2,4-toluenediisocyanate, and one drop (0.02 
g) of dibutyltin dilaurate was prepared and stirred overnight (ca. 15 
hours) at room temperature. 1,3-Butanediol (0.07 g) was added to the 
cloudy solution. Stirring was continued for 0.5 hour after which 1.468 g 
of 1-triethoxysilyl-3-N-methylaminopropane was added to the solution. 
Stirring was maintained for another 1 hour. IR spectral analysis of the 
solution confirmed the absence of any unreacted isocyanate group. The 
solution (36.33% solids) was saved for use in subsequent coatings. 
Coating of Perfluoroether Solutions 
5% by weight solutions was prepared by diluting each of the above polymer 
stock solutions with the required amount of FC-113. One drop (0.01 g) of 
Dow Corning 176 tin catalyst was added to these 5% solutions. The 
solutions were then coated with a #8 Meyer bar onto a piece of organic 
photoreceptor. The photoreceptor (see U.S. Pat. No. 5,124,220) has an 
aluminized film base, a photoconductive layer having 
bis-5,5'-(N-ethyl-benzoa!carbazolyl)phenylmethane (BBCPM) in Vitel.TM. 
PE-207 polyester resin (Goodyear), and a heptamethine indocyanine dye. An 
intermediate layer of 
1,3-bis(3-2,2,2-triaryloyloxymethyl)ethoxy-2-hydroxypropyl!-5,5-dimethyl- 
2,4-imidixolidinedione, Irgacure.TM. 184 photoinitiator (Ciba-Geigy), and 
fluorocarbon surfactant in ethanol was coated over the photoconductive 
layer, dried and cured. The overcoated photoconductor sheets were 
thermally cured at 80.degree.-90.degree. C. for 5-10 minutes and allowed 
to age at room temperature for two days prior to testing. The calculated 
coating thickness was approximately 0.9 .mu.m 
The above made photoconductor constructions were subjected to the following 
tests: 
Isopar L Resistance 
To measure the durability of the release overcoats, an Isopar L soaked 
Q-tip was rubbed across the release overcoated organic photoconductor 
numerous times. The rubbed area was written on with a 3M non-permanent 
transparency pen. Dewetting of the pen's ink indicated the presence of 
release overcoat, while wetting indicated the overcoat had been rubbed off 
the organic photoconductor. 
Peel Force 
To evaluate the release property, 3M 202 masking tape, 1" (2.54 cm) wide, 
was applied to the surface of the release coated organic photoconductor 
constructions with a 15 lb. (6.8 kg) roller. The tape was peeled off at a 
rate of 20 inches/min (50.8 cm/min) for 10 sec. a 90 degree angle while 
the peel force between the tape and the release overcoat was being 
measured. 
Toner Transfer 
To study toner transfer to an intermediate transfer material, magenta toner 
was electroplated (500 Volts, 30 sec.) on 1.25".times.4' (3.175 
cm.times.10.16 cm) release overcoated organic photoconductor strips. The 
magenta toner was comprised of the solubilizing groups as described in the 
specification column 9, lines 49-56, U.S. Pat. No. 4,925,766 which is 
incorporated by reference. It was made at a charge direction level of 0.03 
g Zr HEXCEM/g pigment and an organosol/pigment ratio of 4 using Sun 
Pigment Red 48:2 magenta pigment. The organosol was made at core/shell of 
3 with PS 429 (Petrarch Systems, Inc., a polydimethylsiloxane with 
0.5-0.6% methacryloxypropylmethyl groups, which is trimethylsiloxy 
terminated) and a core comprised of 70% ethyl acrylate and 30% methyl 
methacrylate. The organosol mean diameter was 239 nm, and the organosal 
was made at 10% solids. Air dried strips were placed toner side down onto 
a previously coated surface of Dow Corning 730 fluorosilicone and hand 
pressed at room temperature. The overcoated organic photoconductor was 
then peeled off to observe the quality of toner transfer. 
The results shown in the Table below indicate that the release layers 
(Samples 6 and 7) of this invention have the desired combination good 
resistance to Isopar L, good durability, and good release properties. 
Sample 7 has the best combination of Isopar L rubbing resistance (high rub 
number), low peel force (good release) and good toner transfer. Sample 6 
has the second best combination of properties. In short, the 
perfluoroether-urethane-silane system of this invention have good release 
with better durability. 
Although the Isopar L rubbing resistance of the fluoro-urethane of Sample 2 
is an improvement over Sample 1, high peel force indicates poor release. 
Samples 1 and 5 have a low peel force (good release) but poor Isopar L 
rubbing resistance. Finally, two perfluoroether-urethane systems (Samples 
3 and 4) having similar composition and formulation to that described in 
U.S. Pat. No. 4,996,125 were evaluated. The results obtained for sample 4 
had a high peel force and corresponding poor toner transfer while sample 3 
had poor Isopar L rubbing resistance. 
______________________________________ 
Isopar L Resistance 
Peel (number of rubs 
Force required for ink 
Toner 
Sample 
Release Overcoat 
(oz/in) wetting) Transfer 
______________________________________ 
1 Syl-Off .TM. 23 
0.72 &lt;30 complete 
2 Fluoro-urethane; 
18.0 .about.80 not 
94692-19 available 
3 Perfluoroether; 
5.0 .about.10 complete 
A:B, 1:2 
4 Perfluoroether; 
13.2 &lt;50 none 
A:B:A, 1:2:1 
5 Perfluoroether; 
0.4 .about.10 not 
A:C, 1:2 available 
6 Perfluoroether; 
0.3.about.2.0 
.about.50 complete 
A:B:C, 1:2:2 
7 Perfluorether; 
0.5.about.2.0 
&gt;150 complete 
A:B:D:C, 
1:2:0.1:1.9 
______________________________________ 
*A = perfluoroether diol, A' = perfluoroether diester, B = 2,4toluene 
diisocyanate, D = 1,3butanediol, C = Nmethylaminopropyltriethoxysilane 
Reasonable modifications and variations are possible from the foregoing 
disclosure without departing from either the spirit or scope of the 
present invention as defined by the claims.