Metal oxide free fluoroelastomer fusing member containing same

A fluoroelastomer composition free of metal or metal containing compounds, such as metal, metal alloys, metal salts or metal oxide suitable for the upper layer of a fuser roll which does not require the use of mercapto functional active release agents to prevent offset is provided. The fluoroelastomer compositions contain at least 23.4 mole percent hexafluoropropylene. They can be cured by electron beam treatment, fugitive base treatment or by the use of blocked/hindered bases.

BACKGROUND OF THE INVENTION 
The invention relates generally to metal oxide free fluoroelastomer 
compositions and to a fusing member having an outer layer of the 
fluoroelastomer for applying heat and pressure to fix toner particles to 
recording paper. 
A fuser roll is a roller designed to apply direct heat and pressure to a 
toner image. The fluoroelastomer surface permits toner to be fixed to the 
recording paper without adhering to the roller surface and can withstand 
continuous exposure to high temperatures, silicone oils, toners, toner 
additives and paper product residue without unacceptable physical 
degradation. 
In general, when forming images by xerographic processes, an image formed 
of a heat fusible toner powder is selectively disposed on a web-like 
surface of a recording medium, such as paper, by electrostatic forces. 
Toner powders are commonly formed of a mixture of thermoplastic and/or 
thermosetting resin carriers and additives such as amorphous carbon and 
magnetic particles. They are conventionally fixed to the recording paper 
by direct contact with a fuser roll which applies pressure and heat at 
temperatures between about 200.degree. to 400.degree. F. 
The fusing process is conventionally accomplished by feeding a recording 
medium having the toner image thereon between the nip where two mated 
rollers meet. One or both of the rollers are heated, typically by an 
internal heat source within the roller, so that the surface temperature of 
the roller will be above the softening point of the resinous carrier of 
the toner. 
The recording medium with the toner image thereon is fed between the two 
rollers which press towards each other to apply direct heat and pressure 
to the toner image. The amount of pressure and the length of time that the 
toner is heated determines the degree of fusing. The actual temperature 
range suitable for fixing toner images to recording paper is referred to 
as the "fusing window". The fusing window, TW can be defined by the 
formula: 
EQU TW=T.sub.OFF -T.sub.MIN 
wherein T.sub.OFF is the Hot Offset temperature and T.sub.MIN is the 
minimum fusing temperature. Hot Offset temperature is the temperature at 
which the cohesive forces within the molten toner layer are less than the 
adhesive forces between the toner and roll surface so that toner adheres 
to the fuser roll. T.sub.MIN is the minimum temperature at which toner can 
be acceptably fixed to the recording paper. This temperature range is 
dependent on the raw materials, type of toner, release agents and the 
pressure applied by the roller. It is important that the toner is fixed 
without "offset" occurring, in order to produce copies of acceptable 
quality. For commercial applications, a fusing window of at least 
30.degree. F. is acceptable for some applications. However, it is 
preferable to have as large a fusing window as possible. Thus, a 
60.degree. F. fusing window is desirable and a 100.degree. F. fusing 
window is particularly ideal. 
Conventional fusing systems have drawbacks. Softened toner generally has an 
affinity for the surface of the fuser roll it contacts. When toner adheres 
to the surface of a fuser roll, it can unintentionally be deposited on an 
unselected portion of the recording medium during the next rotation of the 
roll. This phenomenon is referred to as offset. 
To prevent offset, a thin coating of a release agent such as polysiloxane 
fluid is commonly spread over the surface of the fuser roll which contacts 
the surface of the toner image. The polysiloxane fluid reduces the surface 
free energy of the roll surface and decreases the affinity of the toner 
for the roll. Surface tension values for several conventional fuser roll 
materials are set forth below in Table I. 
TABLE I 
______________________________________ 
Surface Tension of Fuser Roll Materials 
Fuser Roll Surface Surface Tension nMn 
______________________________________ 
Polytetrafluoroethylene (PTFE) 
18.0-18.5 
Polyvinylidene fluoride (PVF.sub.2) 
21-22 
Polysiloxane Compounds 
28-29 
Polyfluorocarbon Elastomers 
35-37 
Polysiloxane Release Agents 
19-21 
______________________________________ 
When compounding or formulating fluorocarbon elastomers, metal oxides are 
typically included to act as an acid accepter, cure activator, reinforcing 
filler and/or as an additive to promote improved chemical resistance. It 
is believed that every commercially available fuser roll having a 
fluoroelastomer surface contains metal oxide particles in at least the 
fluoroelastomer surface layer. U.S. Pat. Nos. 4,257,699, 4,264,181 and 
4,272,179 describe fuser rolls in which additional metal oxide filler 
particles are added to the fluoroelastomer surface material to increase 
the metal oxide content of the surface of the fuser rolls beyond that 
needed to promote cure of the material. Fluoroelastomers described in U.S. 
Pat. No. 5,035,950 contain only so much metal oxide as is necessary to 
effect cure of the high fluorine content material. 
These patents describe that use of a polymer release agent having mercapto 
functional groups applied to the surface of a fuser roll having metal 
oxide filler decreases problems associated with offset. When the 
metal-containing filler in the elastomer surface layer is present in 
sufficient amount, it interacts with the polymeric release agent to 
produce an active release film. This active release film prevents the 
thermoplastic resin toner from contacting the elastomeric material itself 
and accordingly, offset is avoided. 
Although this active release construction has proven to be commercially 
acceptable, it nevertheless has drawbacks. Release agent fluids having 
mercapto functional groups are expensive. They can also present an 
unpleasant odor in the office environment and interfere with the ability 
to write or type on the copy sheet. 
Accordingly, it is desirable to provide an improved fusing system which 
overcomes the shortcomings of the conventional fuser systems described 
above. 
SUMMARY OF THE INVENTION 
Generally speaking, in accordance with the invention, fluoroelastomer 
compositions free of metal or metal containing compounds, such as metals 
or metal oxides, which are particularly well suited for the topcoat of a 
fusing member for applying heat and pressure to fix toner to a recording 
medium are provided. The fluoroelastomer composition can be cured by 
electron beam treatment, fugitive base treatment or the use of 
blocked/hindered amines. A fusing member having metal free fluoroelastomer 
surfaces have advantages over conventional fusing members because they do 
not require the use of expensive mercapto functional active release agents 
to prevent offset. 
Accordingly, it is an object of the invention to provide an improved 
fluoroelastomer composition free of metal or metal containing compounds, 
such as metal oxides. 
Another object of the invention is to provide an improved fuser roll having 
a topcoat of fluoroelastomer free of metal or metal containing compounds 
for fixing toner to a recording medium. 
A further object of the invention is to provide a fuser roll having a metal 
or metal containing compound free fluoroelastomer topcoat for fusing 
without the need to use mercapto functional release agents. 
Still other objects and advantages of the invention will in part be obvious 
and will in part be apparent from the specification and drawings. 
The invention accordingly comprises the several steps and the relation of 
one or more of such steps with respect to each of the others, and the 
composition possessing the features, properties and the relation of 
constituents and the article possessing the features, properties, and the 
relation of elements, which are all exemplified in the following detailed 
disclosure, and the scope of the invention will be indicated in the claims 
.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A fusing member constructed in accordance with an embodiment of the 
invention includes a fluoroelastomer topcoat surface that is substantially 
free of metal and metal containing compounds, such as metal or metal oxide 
particles. The fusing member can be a belt, a flat surface or another 
substrate having suitable shape for fixing toner images to a recording 
medium, such as paper, at elevated temperatures under pressure. A 
preferred fusing member is a fuser roll having a metal core that can be 
hollow, covered with the fluoroelastomer material. A heating element can 
be included within the metal core to heat the fluoroelastomer surface. The 
fuser roll can be used to fix toner powder to a recording medium, such as 
paper, without offset and without relying on the interaction between metal 
oxides and mercapto functional release agent fluids. 
The outer layer of the fusing member is of a fluoroelastomer composition 
having a greater molar content of hexafluoropropylene (HFP) than 
conventional fluoroelastomers. The fluoroelastomer compositions prepared 
in accordance with the invention include more than about 23.4 mole % HFP 
and more preferably more than about 30.0 mole % HFP. A preferred 
composition is a copolymer of vinylidene fluoride (VF.sub.2) and 
hexafluoropropylene (HFP) that includes more than about 69% total fluorine 
by weight, preferably 69 to 71% fluorine by weight. It is preferable to 
include as much HFP as is practical. The molar ratio of VF.sub.2 to HFP is 
preferably less than 2 and more preferably about 1.7 or less. An 
acceptable preferred range is between 1.25 and 1.75. 
The fluoroelastomer composition can also include cure additives, such as 
hexafluoropropylidine diphenol, triphenyl benzyl phosphonium 
chloride/bromide and acid acceptors (though not metal oxides). The 
effectiveness of including higher amounts of HFP than is conventional 
relates to the associated reduction in surface energy at the expense of 
other properties conventionally considered to be more important. 
Fuser rolls having a fluoroelastomer surface substantially free of metal 
containing compounds such as metal oxides can be cured by several methods. 
Crosslinking can be induced by using diamines, a combination of diamines 
and bisphenol or by other organic base treatments such as ammonia vapor 
deposition. Another method involves the use of radiation curing such as 
electron beam treatment. Such techniques are known for the use of curing 
various polymer systems, but are uniformly not employed in the production 
of commercially available fuser rolls, where the mechanical properties of 
polymers having metal oxide particles therein has been the accepted 
material of choice. Base treatment includes the use of blocked/hindered 
amines, "fugitive" bases which will leave the polymer system after attack 
on the polymer material to yield unsaturation sites and electron beam 
treatment. The fugitive base treatment can be conducted in the vapor or 
liquid phases. 
Metal oxide free curing can be accomplished with treatment by 
blocked/hindered amines. These include DIAK 3 (N, N'-D- Cinnamylidene-1, 
6-hexanediamine and DIAK 1 (hexamethylene - diaminecarbamate) which are 
commercially available curing agents sold by DuPont of Wilmington, Del. 
This type of curing is described in Example 1. 
Electron beam processing and methods for estimating the required 
specifications of the electron accelerator are discussed in Becker, R. C., 
"Accelerator Requirements For Electron Beam Processing", Radiat. Phys. 
Chem., vol 14, Pages 353-375 (1975), the contents of which are 
incorporated herein by reference. 
Typically, the fuser roll is conveyed into a chamber where it is bombarded 
by a highly energetic beam of electrons. Curing occurs during the brief 
interval during which the fuser roll is exposed to the electron beam, 
which is spread over the entire surface. 
Additional details regarding electron beam processing can be obtained from 
Radiation Dynamics, Inc., 151 Hartland Blvd., Edgewood, N.Y. 11717. See 
also Cleland, M. R., et al., "High Powered DC Electronic Accelerators For 
Industrial Applications", RDI Technical Information Series TIS 79-6 
presented at the 3rd All-Union Conference on a part accelerators, 
Leningrad, USSR, Jun. 26-28, 1979, the contents of which are incorporated 
herein by reference. Still further details can be found in Bly, J. H. 
"Radiation Curing of Elastomers" presented at the Education Symposium of a 
meeting of the Rubber Division, American Chemical Society, Philadelphia, 
Pa., May 3-6, 1982. 
The curing of elastomeric material by Electron Beam (EB) radiation 
generates carbon-carbon bonds between molecules without using cure agents 
such as metal oxide powders. Compounding for the electron beam is similar 
to that for other curing processes. Commercial applications are well 
developed in the manufacture of wire and cable, rubber tires, heat shrink 
products and others. However, it is believed that this technique has never 
been applied to curing polymer materials for fuser rolls in the absence of 
conventional care system including the use of metal oxides. 
Electron Beam (EB) dosages of 1-40 megarads are acceptable for many 
applications; 3-40 MRads is preferred and 5-20 MRads is more preferred. It 
is useful to include cross linking aids (co-agents) in the polymer 
composition at concentrations of about 1-10 parts by weight per 100 parts 
polymer. EB crosslinkable di or poly functional oligimers include: 1,6- 
Hexanediol Diacrylate, Trimethylol Propane Triacrylate, Bisphenol A Expoxy 
Diacrylate (EBECRYL 3700), TAC (2,4,6- Tris (Allyloxy) - S - Tri -azine 
and TAIC (Triallylisocyanurate). 
A fuser roll test assembly 100 is shown generally in FIG. 1 and applies 
heat and pressure to fuse a quantity of toner particles 12 on a sheet of 
paper 13 between a fuser roll 20 and a pressure roll 30. Fuser roll test 
assembly 100 also includes a release agent application unit 11 including a 
wick 15 for applying release agent to the surface of fuser roll 20. A 
stripper finger 16 facilitates the separation of paper 13 from roll 20. 
FIG. 2 is a cross-sectional view of a fuser roll 200 constructed in 
accordance with an embodiment of the invention. Fuser roll 200 includes a 
hollow middle core 201 covered with a fluoroelastomer surface layer 202. A 
second fuser roll 300 is shown in cross-sectional view in FIG. 3. Fuser 
roll 300 includes an insert 302 covered with a base coat 303 having a tie 
coat 304 disposed thereon and a topcoat 302 disposed on tie coat 304. Base 
coat 303 is preferably 0.5 to 5 mil thick and the overall coating (either 
surface layer 202 or combined layers 303, 304, and 302) should be about 
3-8 mils thick. 
The following Examples describe metal and metal oxide free fluoroelastomer 
compositions and fuser rolls having a topcoat of the composition prepared 
in accordance with the invention. These examples are presented for 
purposes of illustration only, and are not intended to be construed in a 
limiting sense. 
EXAMPLE 1 
A series of conventional fluoroelastomer compositions and metal oxide free 
fluoroelastomer compositions in accordance with the invention were made. 
The fluoroelastomer topcoat composition of five conventional fuser rolls 
having metal oxide therein (A-E) and two metal oxide free fluoroelastomer 
topcoat fuser rolls in accordance with the invention (F and G) are shown 
below in Table II. Compositions A through D contain metal oxide filler 
conventionally used to promote interaction with a mercapto functional 
release agent. Composition E contains no more than sufficient residual 
metal oxide to act as an activator and acid accepter for conventional 
cross-linking of the composition, but insufficient amount to react 
effectively with a mercapto functional release agent. 
The seven compositions A through G were prepared by mixing the components 
with a two roll mixing mill. The polymer was loaded between the two mill 
rolls to obtain a "bank". Cross-blending was obtained by cutting sheets 
off the mill roll until a uniform viscosity is achieved. The powdered 
ingredients were then added over the polymer bank and dispersed therein by 
cutting and cross-blending. The curatives are then added and the 
composition was cut and cross-blended to obtain thorough and uniform 
dispersion of all ingredients. The resulting material was cooled in the 
air, compound tested then used as the surface material for a fuser roll. 
The components can also be mixed with an internal mixer device known in 
the trade as a Banbury. When the fuser roller material is formed using a 
liquid state composition, the components can be effectively prepared by 
"in-situ" mixing techniques. In-situ mixing involves dissolving the 
polymer in a solvent, then adding the powdered ingredients including the 
activator and curatives. In compositions having a tendency to gel rapidly, 
it is preferable to employ a two or three component system to isolate the 
calcium hydroxide and/or the acceptor. 
In compounding or formulating fluorocarbon elastomers, metal oxides are 
conventionally added to act as an acid acceptor, cure activator, 
reinforcent filler and/or at times as an additive to promote improved 
chemical resistance. The use of lead oxide, for example, improves the 
steam and acid resistance of fluoroelastomer compounds and is well known 
in the art. Metal fillers are also added to provide actual release by 
interaction with mercapto functional compounds. However, it has been 
determined that metal and metal oxide free compositions provide advantages 
as a top coat surface in a fuser roll despite the diminished mechanical 
properties. 
TABLE II 
__________________________________________________________________________ 
Fuser Roll Surface Material Compositions 
COMISON METAL OXIDE CONTAING METAL OXIDE FREE 
FLUOROELASTOMER COMPOSITION FLUOROELASTOMER 
Composition A B C D E F G 
__________________________________________________________________________ 
Fluorel 2530 x x x x 100 100 x 
(copolymer of VF.sub.2 and 
HFP) 
L12176 x x x x x x 100 
(copolymer VF.sub.2 and HFP) 
Terpolymer VF.sub.2 HFP 
100 x x x x x x 
& TPE 
Copolymer VF.sub.2 & TPE 
x 100 x 100 x x x 
Terpolymer VF.sub.2, HFP 
x x 100 x x x x 
& TPE & Cure Site 
Monomer 
Cupric Oxide x x 15 15 x x x 
Lead Oxide 15 15 x x x x x 
Magnesium Oxide 
x x 2.0 3 3 x x 
Calcium Hydroxide 
x x 1.0 6 6 x x 
Curative 20 2.5 1.4 x 1.4 x x x 
Curative 30 3.5 2.8 x 2.0 x x x 
Curative 50 x x 5.0 x x x x 
DIAK No. 3 x x x x x 6.0 6.0 
Polymer Data Terpolymer 
Copolymer 
Tetrapolymer 
Copolymer 
Copolymer 
Copolymer 
Copolymer 
of VF.sub.2 HFP 
of VF.sub.2 & 
of VF.sub.2, HFP, 
of VF.sub.2 & 
of VF.sub.2 and 
of VF.sub.2 
of VF.sub.2 and 
& TPE HFP TPE & cure 
HFP HFP HFP HFP 
site monomer 
Total Fluorine (wt. %) 
68.5 66% 69.0% 66% 69.6% 69.6% 70 
HFP Content (molar %) 
18 21 22 21 37 37 44 
VF.sub.2 Content (molar %) 
61 79 55 79 63 63 56 
TFE Content (molar %) 
21 x 23 x x x x 
VF.sub.2 /HFP Ratio (molar) 
3.39 3.76 2.5 3.76 1.70 1.70 1.27 
__________________________________________________________________________ 
______________________________________ 
INGREDIENT DATA 
CHEMICAL MANU- 
COMPOSITION TRADE NAME FACTURER 
______________________________________ 
Terpolymer of VF.sub.2, HFP 
Viton B-50, Fluorel, 
DuPont, 3M 
& TPE with 68.5% 
FT 2430 
flourine 
Copolymer of VF.sub.2 and 
Viton E-45, Fluorel, 
DuPont, 3M 
HFP with 65.9% fluorine 
FC 2145 
Copolymer of VF.sub.2, HFP 
Viton E-60, Fluorel, 
DuPont, 3M 
with 66% fluorine 
FC 2230 
Tetrapolymer of FV.sub.2 and 
Viton GF, Fluorel, 
DuPont, 3M 
HFP TFE and cure site 
FLS 2690 
monomer with 69% 
fluorine 
Copolymer of VF.sub.2 and 
FC 2530 3M 
HFP containing 
phosphonium salt 
accelerator and 
bisphenol crosslinker 
with 69.6% fluorine 
33% dispersion of 
Curative 20 DuPont 
organophosphonium salt 
in Viton E-45 
50% dispersion of 
Curative 30 DuPont 
bisphenol (dihyroxy 
aromatic compound) in 
Viton E-45 
Proprietary accelerator 
Curative 50 DuPont 
and bisphenol curative 
system 
Copolymer of VF.sub.2 and HFP 
L-12176 3M 
containing phosphonium 
salt accelerator and 
bisphenol crosslinker 
with 70% fluorine 
N, N'-Di-cinnamylidene- 
DIAK No. 3 DuPont 
1, 6, hexanediamine 
______________________________________ 
Fuser roll samples were formed by covering a 1.5 inch standard aluminum 
insert with a 4 mil thick fluoroelastomer base coat covered with a 2 mil 
thick topcoat of the materials shown below in Table III. The sample fuser 
rolls were prepared by first mixing the base coat material and topcoat 
material in a two roll mixing mill. The base coat compound was formulated 
by combining 100 parts VITON E-60 (DuPont) fluoroelastomer, 30 parts 
thermal carbon black filler, 12 parts magnesium oxide (as an 
activator/acid accepter) and 5.5 parts blend CURATIVE 20 (DuPont) and 
CURATIVE 30 (DuPont). 
The mixed starting materials were dissolved in a 50:50 blend of methyl 
ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) solvents to 
approximately a 15% solid concentration. The aluminum insert was precured 
with a primer layer of THIXON 300/301 adhesive and then sprayed with the 
base coat solution to a thickness of about 5-6 mils. The coated sample was 
maintained at room temperature to permit residual solvent to evaporate and 
then cured in a circulating oven for up to 24 hours at a temperature of 
150.degree. to 450.degree. F. The sample was then ground to a base coat 
thickness of 3-4 mils. After washing the sample with solvent, it was over 
sprayed with a 15% solid topcoat solution to yield a coating having a 
thickness of 4 to 5 mils. Residual solvent was permitted to evaporate and 
the sample was subjected to final curing in a hot air circulating oven for 
up to 24 hours at 450.degree. F. The topcoat was then ground to a 
thickness of 2 to 3 mils. 
Fusing tests herein were carried out by passing an 8.5.times.11.5 inch 75 
g/m.sup.2 sheet of paper having toner particles thereon between fuser roll 
20 and pressure roll 30 to fuse toner 12 to paper 13. Fuser roll life is 
indicated by the number of sheets of paper that can be successfully fused 
before failure by either offset, mechanical failure or some other 
difficulty. Fuser rolls including metal free compositions F and G from 
Table II were found to be acceptable. 
The above procedure was followed for each of the following Runs 1-5, except 
that the topcoat composition was changed as set forth in Table III and the 
insert was a standard two inch insert. Fuser roll samples produced from 
Runs 1, 2, 3 and 5 were installed and tested in a Xerox 1065 copier. The 
results of each copy life test are shown in Table IV, which demonstrates 
the advantages of a high fluorine content and metal oxide free 
fluoroelastomer composition for fusing application. 
TABLE III 
______________________________________ 
FORMULATION OF TOPCOAT COMPOSITION 
RUN NUMBERS 
INGREDIENTS 1 2 3 4 5 
______________________________________ 
FC 2145 (66% F) 100 x x 100 x 
L 12176 (70% F) x 100 100 x 100 
MAGNESIUM OXIDE 2 2 2 x x 
CALCIUM HYDROXIDE 
4 4 4 X x 
DIAK No. 3 x x x 6 6 
CURATIVE 20 1.4 x x x x 
CURATIVE 30 2.8 x x x x 
______________________________________ 
FC 2145 Copolymer of VF.sub.2 and HFP containing 66% total fluorine by 
weight and a VF.sub.2 /HFP molar ratio of 3.76 
FC 2530 Copolymer of VF.sub.2 and HFP containing 69% total fluorine by 
weight and a VF.sub.2 /HFP molar ratio of 1.70; contains phosphonium salt 
accelerator and bisphenol crosslinker. 
L12176 Copolymer of VF.sub.2 and HFP containing 70% total fluorine by 
weight and a VF.sub.2 /HFP molar ratio of 1.27; contains phosphonium salt 
accelerator and bisphenol crosslinker. 
DIAK NO. 3 N, N.sup.1 -Dicinnamylidene 1, 6 Hexanediamine 
CURATIVE 20 33% dispersion of organophophonium salt in Viton E45 
CURATIVE 30 50% dispersion of bisphenol (dihydroxy aromatic compound) in 
Viton E45 
A comparison was made in Table IV below between fuser rolls having the 
compositions of Runs 1, 2, 3 and 5. 
TABLE IV 
______________________________________ 
Roll Life 
Material Type Release Agent 
Description Non-Functional 
Run # Polydimethysiloxane 
______________________________________ 
1 - 66% F with metal oxide 
6,000 
2 - 69% F with metal oxide 
12,000 
3 - 70% F with metal oxide 
21,000 
5 - 70% F no metal oxide 
115,000 
______________________________________ 
By comparing Examples 1 and 2, it can be seen that including a high HFP 
percentage is associated with 100% increase in roll life. Example 3 having 
70% F shows a 75% increase in roll life compared to Example 2 and a 250% 
increase over Example 1 with 66% F. However, the most dramatic results can 
be seen by comparing Examples 3 and 5. The elimination of metal oxide 
within the fuser roll surface material led to a 450% increase in roll life 
of 94,000 copies. Accordingly, it is preferred to provide a fuser roll 
without any metal oxide in the material. 
During conventional cross-linking, metal oxides are used to generate 
unsaturation in the polymer material. However, the reaction is generally 
not easy to control and accordingly, it is has been common to employ 
excess metal oxides to achieve acceptable results. However, this typically 
generates excess unsaturation. The unsaturation in the cured polymer 
material increases the surface energy and may decrease fuser roll life 
before offset occurs. The metal particles at the roll surface also 
increase the surface energy. 
It has been discovered that by carefully controlling the curing of 
metal-oxide free polymer material, sufficient cross-linking is achieved to 
cure the polymer and also provide acceptable mechanical properties, 
without creating excessive unsaturation and without any residual material 
to increase the surface energy of the fuser roll. Metal free compositions 
in accordance with the invention include sufficient sites for 
cross-linking, but not excessive sites which would oxidize, thereby 
increasing surface energy and impede toner release. Furthermore, without 
residual metal oxide particles, the composition will inherently yield a 
polymer surface having lower surface energy particularly well suited for 
fusing applications. 
EXAMPLE 2 
A fuser roll is prepared in accordance with Example 1, employing L-12176 as 
the surface material, which is sprayed onto a procured base layer having a 
4 mil thickness. The surface material is air dried and then positioned in 
an electron beam apparatus curing device and exposed to an energy dose of 
15 MRad. The resultant fuser roll will perform acceptably with 
polydimethylsiloxane release fluid having a viscosity of about 500 CSTKS 
and will exhibit excellent roll life and release properties, including 
adequate release at a temperature of about 185.degree. C. 
EXAMPLE 3 
A fuser roll is prepared as in Example 2, except that the top coat material 
is formed of 100 parts L-12176 together with five parts EBECRYL 3700. 
EBECRYL 3700 (available from RADCURE of Louisville Ky.) is a conventional 
metal-oxide free cross-linking aid (co-agent) that has been found to 
improve the efficiency of electrons beam cures. The roll is cured with an 
electron beam dosage of about 5 MRad's and will perform similarly to the 
roll of Example 2. 
EXAMPLE 4 
Curing without metal oxides can also be effected by treatment with a base 
in either the vapor or liquid phase. For example, ammonia, methylamine, 
ethylamine and dimethylamine gas can be passed over a fuser roll coated 
with metal oxide free fluoroelastomer material. The base will attack the 
polymer chain and create unsaturated sites for cross-linking. Subsequent 
heat treatment will cure the material and provide a fuser roll surface 
having exceptional release properties that does not require interaction 
with a mercapto functional release agent. 
Base treatment as described herein can also be accomplished in the liquid 
phase. The above-noted gaseous materials can be solved in a suitable 
solvent, such as ether or alcohols and the uncured fuser roll can be 
completely immersed therein. Propyl and butyl amines can also be employed, 
as well as combinations of the above bases. 
EXAMPLE 5 
A fuser roll is prepared as in Example 1, except that the surface layer is 
formed of L-12176 which is sprayed onto the precured base layer. The 
surface material is air dried and placed in a cylindrical stainless steel 
chamber equipped with a gas inlet and exhaust apparatus. A gaseous mixture 
of 5% anhydrous ammonia and 95% N.sub.2 (by volume) is allowed to flow 
over the roll surface until sufficient unsaturation is developed as can be 
evidenced by a change in surface color or through instrumental analysis. 
The roll is then removed and placed in a forced air oven at a temperature 
of about 200.degree. C. for about 24 hours. It will perform well with a 
polydimethylsiloxane release fluid having a viscosity of 500 CSTK at 
surface temperatures of about 185.degree. C. 
EXAMPLE 6 
A fuser roll is prepared as in Example 1, except that the surface layer is 
formed of Fluorel 2530 which is sprayed onto a precured base layer. The 
Fluorel layer is air dried and then placed in a cylindrical steel chamber 
equipped with gas inlets and outlets. A gaseous mixture of 5% anhydrous 
ammonia and 95% N.sub.2 (by volume) is allowed to flow over the roll 
surface. The roll is then removed and placed in a forced air oven at 
200.degree. C. for 24 hours. The roll will exhibit adequate release with a 
500 CSTK linear reactive polydimethylsilicone fluid copolymer containing 
0.1 wt % mercaptopropylmethylsiloxane modification at temperatures of 
about 185.degree. C. 
EXAMPLE 7 
A fuser roll is prepared as in Example 1, except that the surface layer is 
formed of L-12176. The material is cured by immersing the fuser roll in a 
10 wt % solution of butylamine in diethylether at 25.degree. C. until 
surface discoloration is apparent. The roll is then removed from the 
amine-ether solution and washed with ethyl alcohol and distilled water. It 
is then heat treated at 200.degree. C. for 24 hours. The roll will exhibit 
adequate release properties at temperatures of about 85.degree. C. with a 
500 CSTK liner polysiloxane release fluid. 
It will thus be seen that the objects set forth above, among those made 
apparent from the preceding description, are efficiently attained and, 
since certain changes may be made in carrying out the above method, and in 
the composition and article set forth without departing from the spirit 
and scope of the invention, it is intended that all matter contained in 
the above description and shown in the accompanying drawings shall be 
interpreted as illustrative and not in a limiting sense. 
It is also to be understood that the following claims are intended to cover 
all of the generic and specific features of the invention herein described 
and all statements of the scope of the invention which, as a matter of 
language, might be said to fall therebetween. 
Particularly it is to be understood that in said claims, ingredients or 
compounds recited in the singular are intended to include compatible 
mixtures of such ingredients wherever the sense permits.