Roll useful in electrostatography

Rolls with improved properties having an outer layer comprising cured fluoroelastomer containing pendant polydiorganosiloxane segments that are covalently bonded to the backbone of the fluoroelastomer. The outer layer provides a release surface that is abhesive to heat-softenable toner material.

FIELD OF THE INVENTION 
This invention relates to a roll that is useful in electrostatography. In 
one aspect, the invention concerns a fusing roll having an outer layer 
comprising cured fluoroelastomer in which pendant polydiorganosiloxane 
segments are covalently bonded to the backbone of the fluoroelastomer to 
provide a release surface abhesive to heat-softenable toner material. 
BACKGROUND 
In certain electrostatographic imaging and recording processes such as 
electrophotographic copying processes, an electrostatic latent image 
formed on a photoconductive surface is developed with a thermoplastic 
toner powder which is thereafter fused to a substrate. The fusion step 
commonly involves directly contacting the substrate, such as a sheet of 
paper on which toner powder is distributed in an imagewide pattern, with a 
heated roll. In most instances as the powder image is tackified by heat, 
part of the image carried by the sheet sticks to the surface of the roll 
so that as the next sheet is advanced, the tackified image partially 
removed from the first sheet partly transfers to the next sheet and at the 
same time part of the tackified image from the next sheet adheres to the 
heated roll. Any toner remaining adhered to the heated surface can cause a 
false offset image to appear on the next sheet that contacts the fusing 
roll and can also degrade the fusing performance of the fusing surface. 
To prevent toner offset, many expedients have been tried such as providing 
the fusing roll with an abhesive surface such as a thin coating of an 
elastomer, e.g., a fluoroelastomer, or a silicone polymer of low surface 
energy. Also polymeric release oils, e.g., polydiorganosiloxane release 
oils such as polydimethylsiloxane release oils have been applied to the 
fuser roll surfaces. With such materials, however, problems can occur. One 
problem is that the elastomers and silicone polymers are difficult to wet 
with polymeric release oils and the application of excessive amounts of 
such oils to the surfaces of fuser rolls in order to achieve sufficient 
surface wetting can cause oil stains on the paper to which toner is being 
fused. 
U.S. Pat. Nos. 4,264,181 and 4,272,179 describe fuser rolls having surfaces 
comprising fluoroelastomers and metal-containing fillers that provide 
sites that react with functionalized polymeric release agents such as 
mercapto-functional polydiorganosiloxane release agents to provide a 
surface abhesive to toner materials and reduce toner offset. 
Unfortunately, as such fuser rolls wear, fresh active sites that are 
exposed react not only with the functionalized polymeric release agents 
but also react with various components of the toner materials and the 
paper substrate. Such reaction builds up debris on the surface of the 
fuser roll which results in permanent damage to such surface. This greatly 
reduces the life of the fuser roll. Additionally, the metal-containing 
filler particles are physically torn from the fuser surface during use 
which also reduces the life of the fuser roll. It is evident, therefore, 
that there is a need in the prior art for a roll that is not subject to 
the problems described hereinbefore and exhibits improved resistance to 
offset and increased useful fusing life. An objective of this invention is 
to provide such a fusing roll. 
SUMMARY OF THE INVENTION 
The present invention provides a roll useful for fusing heat-softenable 
toner material to a substrate. The roll has an outer layer comprising 
cured fluoroelastomer having pendant polydiorganosiloxane segments that 
are covalently bonded to the backbone of the fluoroelastomer. Such 
segments have a number average molecular weight in the range of about 
1,000 to 20,000. 
The outer layer described provides a release surface which minimizes toner 
offset. This release surface is achieved without significant sacrifice in 
the desirable physical properties, for example, physical strength of the 
fluoroelastomer. Furthermore, as illustrated in the following Examples, 
incorporation of a relatively small concentration of the pendant 
polydiorganosiloxane segments into the fluoroelastomer in accordance with 
this invention achieves an increase in the life of a fuser roll well 
beyond that which could reasonably be expected for such a seemingly small 
modification. In addition, the incorporation of the pendant 
polydiorganosiloxane segments into the fluoroelastomer can serve as an 
internal lubricant that reduces the overall wear of the surface of a fuser 
roll, a potential initiating step to toner offset. Additional advantages 
will be described hereinafter. 
DESCRIPTION OF PREFERRED EMBODIMENTS 
The cured fluoroelastomers that are used in the practice of this invention 
are obtained by covalently bonding polydiorganosiloxane segments to the 
backbone of a non-cured fluoroelastomer. Such segments are appended to the 
backbone of the cured fluoroelastomer as opposed to being an integral part 
of that backbone as would be the case in a random or block copolymer 
comprising fluorocarbon moieties. Accordingly, these polydiorganosiloxane 
segments are frequently referred to herein as being pendant 
polydiorganosiloxane segments. The non-cured or non-crosslinked 
fluoroelastomer base polymers that are modified by the incorporation of 
the pendant polydiorganosiloxane segments are known materials and have 
been used in the preparation of fuser roll surfaces. See, for example, 
U.S. Pat. Nos. 4,257,699; 4,264,181; and 4272,179. The required 
diorganosiloxane segments can be conveniently appended to the backbone of 
the cured fluoroelastomer during curing of the fluoroelastomer base 
polymer by simply adding to the composition to be cured, a 
polydiorganosiloxane oligomer containing appropriate functional groups 
such as phenoxy or amino groups. At least one of these functional groups 
must be present on a polydiorganosiloxane chain in the oligomer to form 
the covalent bond the the fluoroelastomer backbone. Such groups react with 
the fluoroelastomer base polymer as a result of dehydrofluorination of the 
base polymer which take place during curing. Fluoroelastomer base polymers 
that can be used are polymers of ethylenically unsaturated 
fluorohydrocarbons. Fluoroelastomers derived from many of these 
fluorohydrocarbons, including vinylidene fluoride, hexafluoropropylene and 
perfluoroalkylvinyl ethers are commercially available from a number of 
suppliers and generally have glass transition temperatures (Tg) in the 
range of about 0.degree. to 10.degree. C. Useful fluoroelastomers are 
vinylidene fluoride-based fluoroelastomers which contain 
hexafluoropropylene as a comonomer. Two classes of suitable 
fluoroelastomers are (1) copolymers of vinylidene fluoride and 
hexafluoropropylene, known commercially as Viton A, and (2) terpolymers of 
vinylidene fluoride with hexafluoropropylene and tetrafluoroethylene, 
known commercially as Viton B. Viton A and Viton B are trademarks of E. I. 
duPont & Co. 
The fluoroelastomer base polymers can be cured using a basic nucleophile 
cure system of the type described in U.S. Pat. Nos. 4,257,699, 4,264,181, 
and 4,272,179 referred to previously herein. Such a cure system generally 
employs a bifunctional agent such as a bisphenol or a diamine carbamate to 
generate a covalently crosslinked polymer network formed by the 
application of heat following basic dehydrofluorination of the polymer. 
The basic dehydrofluorination reaction requires the presence in the 
formulation being cured of a basic metal oxide such as magnesium oxide, 
calcium oxide or lead oxide. The basicmetal oxide reacts with acidic 
by-products that are believed to include hydrogen fluoride and/or 
derivatives thereof, that are generated during curing of the 
fluoroelastomer. The incorporation of a polydiorganosiloxane oligomer 
containing appropriate reactive groups with the essential ingredients of a 
basic nucleophilic addition curing system results in covalently bonding 
pendant polydiorganosiloxane segments to the backbone of the 
fluoroelastomer base polymer while it is being cured. Depending upon the 
number of the reactive groups on the polydiorganosiloxane oligomer the 
pendant segments can form branches on the fluorocarbon backbone of the 
fluoroelastomer base polymer and/or enter into the crosslink network of 
the cured fluoroelastomer. The primary reactions involved in the basic 
nucleophile curing system described in the aforementioned three U.S. 
Patents are also disclosed and discussed in various journals and articles 
including a paper entitled "Viton Fluoroelastomer Crosslinking by 
Bisphenols" written by W. W. Schmiegel and presented at the South German 
Meeting of the Deutsche Dautshuk Und Gummi Gesellschaft, Apr. 28-29, 1977. 
One example of the nucleophilic addition cure system is the bisphenol 
crosslinking agent with organophosphonium salt accelerator. The 
phosphonium salt may be exemplified as: 
##EQU1## 
where .phi. represents phenyl groups, and the bisphenol is examplified as: 
##STR1## 
Another example of the nucleophilic addition cure system is crosslinking 
with a diamine carbamate type curing agent commonly known as DIAK 1. The 
following scheme showing three separate reactions represents the curing of 
copoly(vinylidene fluoride-hexafluoropropylene) with diamine carbamate as 
the curing or crosslinking agent: 
##STR2## 
where step 1 shows the loss of HF in the presence of a base; step 2 shows 
the insertion of the diamine carbamate agent; and step 3 shows post cure 
in the presence of heat. This mechanism is well known in the art as a 
crosslinking or curing system. Examples of diamine carbamate cure systems 
are hexamethylenediamine carbamate known commercially as DIAK No. 1 and 
N,N'-dicinnamylidene-1,6-hexanediamine known commercially as DIAK No. 3 
(DIAK is a trademark of E. I. duPont & Co.). 
A critical feature of the cured fluoroelastomers employed in the practice 
of this invention is that they comprise a backbone having pendant 
polydiorganosiloxane segments covalently bonded thereto. Such cured 
fluoroelastomers exhibit superior properties in fuser rolls in comparison 
to cured fluoroelastomers of the prior art that do not contain such 
segments. Thus, such segments provide an "internal lubricant" for the 
fuser surface which is abhesive to heat-softenable toner materials. Such 
an internal lubricant provides a relatively low surface energy coating for 
the fuser roll and facilitates uptake and wetting of release fluids that 
are applied to the fusing surface. The polydiorganosiloxane segments can 
be covalently bonded to the backbone of the cured fluoroelastomer by any 
method known to the prior art to be suitable for this purpose. However, 
using a basic nucleophilic addition curing system as previously described 
herein, is a very convenient method of incorporating the 
polydiorganosiloxane segments into the cured fluoroelastomer backbone. The 
desired cured fluoroelastomer can be synthesized by reacting a 
polyfunctional diorganosiloxane oligomer, for example, a 
diaminoalkyl-terminated oligomer with the non-cured fluoroelastomer during 
the cure cycle. Suitable polydiorganosiloxanes include the homo and 
copolymers that are well known and can be selected by those skilled in the 
art to provide the optimum release properties using at most, only minimum 
routine experimentation. Typically the organo groups in the oligomers are 
normally free of aliphatic unsaturation and include such radicals as 
alkyl, e.g., methyl, ethyl, propyl, octyl; cycloalkyl, e.g., cyclopentyl 
and cyclohexyl; aryl, e.g., phenyl; aralkyl, e.g., benzyl and halogenated 
derivatives of the aforementioned radicals, e.g., chloromethyl, 
trifluoromethyl, dibromophenyl and tetrachlorophenyl. Although the 
polydiorganosiloxane oligomer employed can be any oligomer that is 
compatible with the curing composition and which yields cured 
fluoroelastomer containing the desired polydiorganosiloxane segments, the 
preferred oligomers are .alpha.,.omega.- difunctional 
polydiorganosiloxanes such as bis(aminopropyl)terminated 
poly(dimethylsiloxanes). Such oligomers are available in a series of 
molecular weights as disclosed, for example, by Yilgor et al, "Segmented 
Organosiloxane Copolymers", Polymer, 1984, V. 25, pp. 1800-1806 and in a 
treatise entitled "Block Copolymers" by Noshay and McGrath, Academic Press 
(1977), pages 392-428. They are prepared, as described by McGrath et al by 
the ring opening equilibration of octamethylcyclotetrasiloxane in the 
presence of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and an initiator. 
A preferred class of polydiorganosiloxane oligomers, based upon 
availability, includes those having functional groups including amines, 
phenols and thiols which provide the covalent bonding with the backbone of 
the cured fluoroelastomer. Examples of such oligomers that can be used in 
the practice of this invention can be represented by the following general 
formula: 
##STR3## 
where 
R is lower alkyl or haloalkyl such as methyl, ethyl, fluoropropyl or aryl 
such as phenyl; 
R' is lower alkylene such as methylene, ethylene or isopropylene or arylene 
such as phenylene; 
X is a functional group having an active hydrogen such as --OH, --NH.sub.2, 
--NR"H, --SH, --NHCO.sub.2.sup.74, where R" is hydrogen or lower alkyl. 
n, m and o are positive integers such that n+m+0 provides a number average 
molecular weight (Mn) in the range of about 1,000 to 20,000, often about 
2,000 to 14,000. The number average molecular weight (Mn) of the uncured 
fluoroelastomer used in this invention is generally in the range of about 
75,000 to 125,000, often about 100,000. 
The number average molecular weight of the polydiorganosiloxane segments in 
the cured fluoroelastomer is, as previously indicated herein, about 1,000 
to 20,000. At lower molecular weights, no appreciable release effect is 
observed and at higher molecular weights, the physical strength of the 
elastomer shows significant deterioration. A suitable concentration of 
polydiorganosiloxane segments in the cured fluoroelastomer which provides 
the desired release surface on the roll is generally about 1 to 10, often 
3 to 7 weight percent. To achieve such weight percents, up to 15 percent, 
by weight, generally about 5 to 10 percent, by weight of the 
polydiorganosiloxane oligomer is added to the formulation to be cured. 
This latter concentration is based upon the total weight of the 
formulation, including non-cured fluoroelastomer, catalyst, filler and 
other materials present in the formulation. 
The outer layer of the roll of this invention can also contain a filler or 
mixture of fillers. Such fillers are well known in the prior art and are 
conventionally used with fluoroelastomers at concentrations in the range 
of about 10 to 100, often 25 to 75 weight percent, based on the weight of 
the cured fluoroelastomer. Suitable fillers include reinforcing fillers 
such as carbon that improve the physical or thermal properties of the 
layer. A particularly useful filler is a metal-containing filler such as a 
metal, metal alloy, metal salt or metal oxide that reacts with polymeric 
release agents that have functional groups and are applied to the fuser 
roll surface to provide a surface abhesive to heat-softenable toner 
materials. The interaction between the metal-containing fillers and such 
polymeric release agents which are in the form of a liquid or fluid 
provides an excellent surface for release coupled with a propensity of the 
release agent to remain upon the surface of the fuser roll. This 
interaction, the fillers and the polymeric release agents having 
functional groups are well known in the art and are described in detail in 
several U.S. Patents including U.S. Pat. Nos. 4,257,699, 4,264,181, and 
4,272,179. However, a description of such materials at this point may be 
useful to provide a better understanding of the invention. 
The metal oxide, metal salt, metal, metal alloy or other metal compound 
fillers which are used to provide active sites to interact with the 
release oils or fluids, will vary depending upon the particular polymeric 
release agent having functional groups used in a fusing assembly. The 
general classes of metals which are applicable include those metals of 
Groups 1b, 2, 3, 4, 5, 6b, 7b and 8 and the rare earth elements of the 
Periodic Table. In certain instances, especially in salts and alloys, 
certain metals of group 1a of the Periodic Table are also included. 
The metal oxide filler can be any metal oxide that can be incorporated into 
the cured fluoroelastomer without adverse effect upon the fluoroelastomer 
or upon the polymer release agent having functional groups. For example, 
the advantages described herein can be obtained when the metal oxide 
filler dispersed in the cured fluoroelastomer is an oxide of aluminum, 
copper, tin, zinc, lead, iron, platinum, gold, silver, antimony, bismuth, 
iridium, ruthenium, tungsten, manganese, cadium, mercury, vanadium, 
chromium, magnesium, nickel and alloys thereof. One skilled in the art can 
compare the release of various cured fluoroelastomers containing these 
metal oxides to determine the optimum metal oxide or combination thereof 
and concentrations thereof. For example, when the polymeric release agent 
is one having mercapto functional (thio functional) groups, the preferred 
metal-containing fillers, are those that interact with the sulfur in the 
mercapto-functional group to form metal sulfides. Metal oxide fillers such 
as lead oxide that also take part in the basic dehydrofluorination 
reaction during curing of the fluoroelastomer base polymer are often 
preferred because their use in the curable composition eliminates the need 
for a second filler that will interact with the polymeric release agents 
that have functional groups. In those embodiments where thermal 
conductivity is of significance, preferred metal oxide fillers are those 
which have greater thermal conductivity. Thus, more desirable metal oxide 
fillers dispersed in the cured fluoroelastomer may comprise copper, silver 
or gold. 
When metal fillers are used, any stable metal or metal alloy may be used as 
long as there is no adverse effect upon the cured fluoroelastomer or the 
polymeric release agent having functional groups and as long as the metal 
or metal alloy interacts with the functional group or groups of the 
polymeric release agent. Exemplary of the metal or metal alloy fillers 
useful in the present nvention are aluminum, copper, tin, zinc, lead, 
beryllium, iron, platinum, gold, silver, iridium, ruthenium, tungsten, 
vanadium, cadmium, chromium, manganese, magnesium, bismuth, antimony, 
nickel and alloys of the foregoing metals. 
Metal salts may also be used in accordance with the present invention. Any 
stable salt or salts of the metals discussed relative to their location in 
the Periodic Table of Elements capable of interacting with the functional 
group or functional groups of the polymeric release agent may be used as a 
filler as long as there is no adverse effect upon the cured 
fluoroelastomer or the polymeric release agent having functional groups. 
For example, when the functional group of the polymeric release agent is 
hydroxyl, then the metal salt must interact with the oxygen in the 
hydroxyl group to form a metal-oxygen interaction product. Exemplary of 
some of the metal salts useful in the present invention are the acetates, 
halides (chlorides, fluorides, iodides, and bromides), carbonates, 
sulfides, sulfates, phosphates, or nitrates of lithium, sodium, potassium, 
calcium, iron, nickel, copper, zinc, aluminum, cadmium, silver, lead, tin, 
gold, chromium, or tungsten. Preferred metal salts are the salts of heavy 
metals that are highly insoluble in the polymer release agent since there 
is less tendency for such salts to dissolve in such release agent and 
produce an adverse effect such as gelation. 
The rolls of this invention can be used with conventional release agents 
(oils or fluids) that are normally applied to the active surface of a 
fuser roll to enhance toner release. Such materials include, for example, 
silicone fluids of both low and high viscosity and poly(dimethylsiloxane) 
oils. The preferred class of release agents are polymeric release agents 
having functional groups since such release agents can be used in 
conjunction with fuser rolls containing the metal-containing fillers to 
achieve the advantages described previously herein. Suitable release 
agents include those described in U.S. Pat. Nos. 4,029,827, 4,078,285, 
4,011,362, 4,101,686, and 4,046,795, 4,257,699, 4,264,181 and 4,272,179. 
The outer layer that forms the working surface of the roll of this 
invention comprises the cured fluoroelastomer and optionally conventional 
addenda such as antioxidants, stabilizers and release agents that further 
reduce the adhesion of heat-softenable toner material to a fuser roll. 
Examples of such release agents are poly(tetrafluoroethylene), boron 
nitride and fluorinate graphite. Such release agents can be blended with 
the non-cured fluoroelastomer in a concentration of about 5 to 25 weight 
percent. This outer layer is generally about 15 to 75 .mu.m, often about 
20 to 30 .mu.m thick. 
The roll of this invention comprises a cylindrical core coated with one or 
more layers, including the outer layer or working surface of this 
invention. A suitable core comprises any rigid metal or plastic substance, 
including, for example, aluminum, steel, and various alloys and polymeric 
materials such as thermoset resins, with or without fiber re-enforcement. 
The fuser roll can be fabricated by first preparing a mixture of the 
non-cured fluoroelastomer and any other addenda such as fillers and 
release agents desired to be included in the working surface of the roll. 
The mixture is blended on compounding rolls to achieve a homogeneous 
blend. The resulting blend is then dispersed in a suitable solvent such as 
methylethylketone or methylisobutyl ketone. The polydiorganosiloxane 
oligomer in the form of a liquid or oil is added to the dispersion. 
The composition is then coated on a suitable substrate to form the outer 
layer of the fuser roll. The coating can be achieved using any convenient 
technique including gravure or spray coating. The substrate can be an 
aluminum or steel cylinder and it can comprise primer or other underlayers 
well known in the art. One skilled in the art can easily select one of the 
many well known adhesives or primers available for adhering particular 
fluoroelastomrs to substrates. Also, a wide variety of underlayers are 
well known for use in fuser rolls, for example, as resilient layers that 
aid in forming a suitable nip for the production of high quality copies. 
The outer layer is permitted to dry in air to remove volatile solvents and 
is then subjected to nucleophilic addition curing as described previously 
herein. It is during this curing period that the polydiorganosiloxane 
segments covalently bond to the backbone of the fluoroelastomer. The 
curing treatment is preferably carried out, at least in part, at 
temperatures of at least 230.degree. C. The curing treatment can be 
carried out in stages, for example, an initial state where the temperature 
of the composition is ramped (gradually raised) from about 20.degree. C. 
to about 230.degree. C. over a period of about 12 to 24 hours and then 
cured at that temperature or slightly higher, e.g., 232.degree. C. for 
about 24 hours. 
The outer layer comprising cured fluoroelastomer having pendant 
diorganosiloxane segments, as described herein, can be applied to a roll 
other than a fuser roll to provide a release surface that is abhesive to 
heat-softenable toner materials that may come into contact with such a 
roll. For example, fuser rolls of the type described herein are typically 
used in a pressure fusing system where the fuser roll and a pressure roll 
(also referred to as a backup roll) define a contact arc between the rolls 
wherein toner images are fused to a substrate. In such a system an 
applicator roll (also referred to as an oiling roll) may be used to apply 
release agent to the outer layer or working surface of the fuser roll to 
prevent toner offset. Such pressure or applicator rolls can comprise an 
outer layer of the cured fluoroelastomer having pendant 
polydiorganosiloxane segments to provide the desired release surface. 
Rolls of this invention have been used as fuser rolls and have also been 
tested to determine various physical properties thereof. When used as 
fuser rolls, with application of heat and various release fluids thereto, 
the rolls have exhibited good fusing performance and durability over long 
copy runs. Furthermore, it has been found that the type of 
polydiorganosiloxane segments that are covalently bonded to the backbone 
of the cured fluoroelastomer can be adjusted to make them structurally 
compatible with organosiloxane polymeric units present in many release 
oils so that the segments absorb a limited and controlled amount of 
release oil. The benefit of this is that the outer layer of the fusing 
roll serves as a reservoir for release oil in the event of any 
interruption in the normal supply of release oil to the surface of the 
roll. If such oil supply is interrupted, the oil retained by the fusing 
roll outer layer of this invention prevents any immediate image defects, 
which would normally occur when a non-absorbing polymer such as a prior 
art cured fluoroelastomer is used as a fusing surface. Also, the 
aforementioned compatibility allows the polymeric release agent to be more 
intimately bound to the surface of the fuser roll then would be the case 
where no polydiorganosiloxane segments are present in the cured 
fluoroelastomer. 
Likewise, because of its balanced polydiorganosiloxane segment content, the 
entire surface of the fuser roll is readily wetted by a reasonably small 
amount of release oil. In contrast, a covering such as a prior art 
fluoroelastomer which is more incompatible with release oil, requires an 
excessive amount of the oil to cover its surface. As a consequence of 
having to use so much oil to obtain release of the heat-softenable toner 
material, the oil stains the paper on which toner is being fused by the 
fuser roll. 
It is particularly advantageous to have polydiorganosiloxane segments 
present in the fuser rolls of this invention when such rolls also contain 
metal-containing fillers and are used in conjunction with polymeric 
release agents containing functional groups that interact with such 
fillers. Thus, the polydiorganosiloxane segments provide a boundary layer 
on the surface of the fuser roll which prevents toner material from 
contacting the high energy metal containing fillers to form reaction 
products that build up on the surface of the fuser roll and reduce its 
useful life. 
The fusing rolls of this invention are used for fusing heat-softenable 
toner materials of the type that are well known and have the physical 
properties required in dry electrostatographic toner materials. Such toner 
materials or particles can be thermally fixed or adhered to a receiving 
sheet such as paper or plastic. These termal fixing techniques are well 
known in the art. 
Many polymers have been reported in literature as being useful in dry 
electrostatographic toners. Polymers useful in such toners include vinyl 
polymers, such as homopolymers and copolymers of styrene and condensation 
polymers such as polyesters and copolyesters. Fusible styrene-acrylic 
copolymers which are covalently lightly crosslinked with a divinyl 
compound such as divinylbenzene, as disclosed in the patent to Jadwin et 
al, U.S. Re Pat. No. 31,072, are useful. Also useful are polyestes of 
aromatic dicarboxylic acids with one or more aliphatic diols, such as 
polyesters of isophthalic or terephthalic acid with diols such as ethylene 
glycol, cyclohexane dimethanol and bisphenols. Examples are disclosed in 
the patent to Jadwin et al. 
Fusible toner particles used in this invention can have fusing temperatures 
in the range from about 50.degree. C. to 200.degree. C. so they can 
readily be fused to paper receiving sheets. Preferred toners fuse in the 
range of from about 65.degree. C. to 120.degree. C. If the toner transfer 
is made to receiving sheets which can withstand higher temperatures, 
polymers of higher fusing temperatures can be used. 
Useful toner particles can simply comprise the polymeric particles but, it 
is often desirable to incorporate addenda in the toner such as waxes, 
colorants, release agents, change control agents, and other toner addenda 
well known in the art. 
If a colorless image is desired, it is not necessary to add colorant to the 
toner particles. However, more usually a visibly colored image is desired 
and suitable colorants selected from a wide variety of dyes and pigments 
such as disclosed for example, in U.S. Reissue Pat. No. 31,072 are used. A 
particularly useful colorant for toners to be used in black-and-white 
electrophotographic copying machines is carbon black. Colorants in the 
amount of about 1 to about 30 percent, by weight, based on the weight of 
the toner can be used. Often about 1 to 8 percent, by weight, of colorant 
is employed. 
Charge control agents suitable for use in toners are disclosed for example 
in U.S. Pat. nos. 3,893,935; 4,079,014; 4,323,634 and British Patent Nos. 
1,501,065 and 1,420,839. Charge control agents are generally employed in 
small quantities such as, about 0.1 to about 3, weight percent, often 0.2 
to 1.5 weight percent, based on the weight of the toner. 
Toners used with a roll of this invention can be mixed with a carrier 
vehicle. The carrier vehicles, which can be used to form suitable 
developer compositions, can be selected from a variety of materials. Such 
materials include carrier core particles and core particles overcoated 
with a thin layer of film-forming resin. Examples of suitable resins are 
described in U.S. Pat. Nos. 3,547,822; 3,632,512; 3,795,618; 3,898,170; 
4,545,060; 4,478,925; 4,076,857; and 3,970,571. 
The carrier core particles can comprise conductive, non-conductive, 
magnetic, or non-magnetic materials. See, for example, U.S. Pat. Nos. 
3,850,663 and 3,970,571. Especially useful in magnetic brush development 
schemes are iron particles such as porous iron particles having oxidized 
surfaces, steel particles, and other "hard" or "soft" ferromagnetic 
materials such as gamma ferric oxides or ferrites, such as ferrites of 
barium, strontium, lead, magnesium, or aluminum. See for example, U.S. 
Pat. Nos. 4,042,518; 4,478,925; and 4,546,060. 
A typical developer composition containing toner particles and carrier 
vehicle generally comprises about 1 to 20 percent, by weight, of 
particulate toner particles and from 80 to 99 percent, by weight, carrier 
particles. Usually, the carrier particles are larger than the toner 
particles. Conventional carrier particles have a particle size on the 
order of about 20 to 1200 micrometers, generally about 30 to 300 
micrometers. Alternatively, the toners can be used in a single component 
developer, i.e., with no carrier particles. 
Typical toner particles generally have an average diameter in the range of 
about 0.1 to 100 .mu.m, a value of about 2 to 20 .mu.m being particularly 
useful in many current copy machines. 
The following preparations and examples are included to illustrate the 
preparation and superior properties of rolls made in accordance with this 
invention. Parts and percentages are by weight unless otherwise specified. 
Roll Preparation 
Cylindrical aluminum cores were cleaned, washed to remove contaminants and 
coated with a conventional silicone priming agent. the primed cores were 
dried and coated with a layer of polydimethylsiloxane elastomer which was 
then cured to provide a resilient underlayer having a dry thickness of 2.5 
millimeters. The roll was surface ground, and cured again. After curing, 
the underlayer was treated to improve adhesion of the outer layer that 
forms a fusing surface according to this invention. 
The outer layer or fusing surface was prepared using a 
fluoroelastomer-based composition described in the following Examples. The 
composition comprising uncured fluoroelastomer base polymer, 
polydiorganosiloxane oligomer, pigment, fillers and curing agents was 
compounded on a 2-roll mill until a uniform blend was obtained. 
The blend was then dispersed in methyl ethyl ketone solvent with stirring 
for a minimum of 2 hours. The dispersion was stirred slowly to avoid 
settling, kept sealed to prevent solvent loss and exposure to atmosphere 
moisture, and then roll coated on the resilient underlayer at a 
temperature of 21.degree. C. (Relative Humidity 50%), to form an outer 
layer having a dry thickness of 30 micrometers. This outer layer was cured 
using the following conditions: 
Air dry 24 hours 
24 hours ramp to 232.degree. C. 
24 hours at 232.degree. C. 
The fuser rolls were "preconditioned" before they were used to thermally 
fix toner particles. This preconditioning was achieved by rotating the 
fuser roll in contact with an aluminum pressure roll. These rolls were 
coated with a silicone release oil Silicone Fluid F655B, a mercapto 
functional polydimethylsiloxane having a viscosity of 10,000 centistokes 
at 25.degree. C. (available from Stauffer-Wacker Silicone Corp.) by means 
of a rotating wick for 10 minutes. The wick was disengaged and the fuser 
roll was rotated in contact with the pressure roll for 4 hours at 
188.degree. C. The fuser roll was ready to use. 
The following examples further illustrate the invention.

EXAMPLE 1 
As previously indicated, the fuser rolls of this invention exhibit 
excellent fuser life and resistance to offset. To illustrate these 
features, the following composition was prepared, coated and cured to form 
the outer layer of a fusing roll according to the Roll Preparation 
procedure described hereinbefore. 
______________________________________ 
Component Grams 
______________________________________ 
Copoly(hexafluoropropylene-vinylidene 
100 
fluoride) number average molecular weight 
100,000 (available from E. I. duPont & Co. 
as Viton A) 
Benzyltriphenylphosphonium chloride curing 
4.5 
agent (available from E. I. duPont & Co. as 
Cure 20) 
4,4'-(2,2,2-trifluoro-1-(trifluoromethyl)- 
6 
ethylidene)bisphenol curing agent 
(available from E. I. duPont Co. as Cure 30) 
Magnesium oxide 3 
Calcium hydroxide 6 
Carbon black (available as 
45 
Thermax MT from R. T. Vanderbilt Co.) 
.alpha.,.omega.-aminopropyl terminated polydimethyl- 
5 
siloxane oligomer, number average molecular 
weight 8,000 
Methyl ethyl ketone 994 
______________________________________ 
The fuser roll was used in the fuser assembly of an Ektaprint 250 
Duplicator (trademark of Eastman Kodak Company) to fix an image of dry 
toner particles comprising yellow pigment, charge agent and polyester 
binder (a polyester of terephthalic acid/glutaric acid (87/13, weight 
percent) and 1,2-propanediol/glycerol (95/5, weight percent). The fusing 
conditions and release oil were as follows: 
______________________________________ 
Fuser roll temperature 
171.degree. C. 
Pressure roll temperature 
171.degree. C. 
Release oil mercapto-functional 
polydimethylsiloxane oil 
(1.4 .times. 10.sup.-4 equivalents 
mercapto/gram fluid), 
viscosity 275 centistokes 
at 25.degree. C. 
______________________________________ 
Approximately 10,000 copies were fused with no evidence of hot offset. This 
illustrates the excellent offset resistance of fuser rolls of this 
invention. 
After 45,000 copies, the fuser roll surface was analyzed for polyester 
buildup. Such buildup is evidence of reaction between the roll surface and 
the polyester binder resin in the toner. A Fourier Transform Infrared 
analysis technique was used to determine carbonyl absorption on the roll 
surface. With this technique, values are reported in terms of units of 
infrared absorption per square millimeter of roll surface, i.e., the 
negative log of the reciprocal of light transmission. The larger the 
number, the greater the concentration of carbonyl on the roll surface and 
the shorter the usable life of the roll. The infrared absorption per 
square millimeter for the fuser roll of this invention was 2. In contrast, 
a roll identical in all respects except that the 
.alpha.,.omega.-aminopropyl terminated polydimethylsiloxane oligomer was 
omitted from the composition, had an infrared absorption per square 
millimeter of 7. This reduction in polyester buildup clearly illustrates 
that the use of cured fluoroelastomers having pendant polydiorganosiloxane 
segments covalently bonded to the backbone of the fluoroelastomer in fuser 
rolls of this invention significantly increases the useful life of such 
rolls. 
EXAMPLE 2 
As indicated previously, metal-containing fillers such as lead oxide can be 
used in the practice of this invention. To illustrate, Example 1 was 
repeated with the following composition. 
______________________________________ 
Component Grams 
______________________________________ 
Copoly(hexafluoropropylene vinylidene 
100 
fluoride) number average molecular weight 
100,000 (available from E. I. duPont & Co. 
as Viton A) 
Benzyltriphenylphosphonium chloride curing 
2.5 
agent (available from E. I. duPont & Co. as 
Cure 20) 
4,4'-(2,2,2-trifluoro-1-(trifluoromethyl)- 
6 
ethylidene)bisphenol curing agent 
(available from E. I. duPont & Co. 
as Cure 30) 
Lead monoxide 15 
Carbon black (available as 
20 
Thermax MT from R. T. Vanderbilt Co.) 
.alpha. ,.omega.-aminopropyl terminated polydimethyl- 
5 
siloxane oligomer, number average molecular 
weight 8,000 
Methyl ethyl ketone 994 
______________________________________ 
After 45,000 copies the fuser roll prepared according to this invention 
showed no evidence of hot offset and the infrared absorption per square 
millimeter was 0. Furthermore, a fuser roll prepared according to this 
procedure but without .alpha.,.omega.-aminopropyl terminated 
polydimethylsiloxane oligomer, had an infrared absorption per square 
millimeter of 1. This clearly demonstrates the superiority of fuser rolls 
containing cured fluoroelastomers having pendant polydiorganosiloxane 
segments according to this invention. 
EXAMPLE 3 
Example 2 was repeated except that a .alpha.,.omega.-aminopropyl-terminated 
dimethylsiloxane oligomers of varying molecular weight and concentrations 
were used to form the fusing rolls. 5 grams of an 
.alpha.,.omega.-aminopropyl polydimethylsiloxane oligomer having a number 
average molecular weight of 14,000 was used to form one roll while an 
.alpha.,.omega.-aminopropyl polydimethylsiloxane oligomer having a number 
average molecular weight of 8,000 was used at concentrations of 2.5, 5, 
7.5, 10 and 15 grams in five other rolls. The six fuser rolls exhibit 
excellent toner release and the life of each of the rolls is comparable to 
the roll described in Example 2 which was prepared according to this 
invention. 
EXAMPLE 4 
The outer layer on a fuser roll of this invention exhibits low surface 
energy which provides a surface that is abhesive to toner materials. To 
illustrate this feature of the invention, fluoroelastomer compositions 
were prepared according to Example 2 using 
.alpha.,.omega.-aminopropyl-terminated polydimethylsiloxane oligomers of 
different number average molecular weight and at varying concentrations. 
Each of the compositions were spray coated on a flat surface and water 
contact angle measurements were made on the coatings after curing. The 
results are set forth in the following table. 
TABLE 
______________________________________ 
Concentration 
Water Contact 
Molecular of Oligomer Angle, Degrees 
Weight of (weight %, Relative to 
Composition 
Oligomer Composition) 
Control 
______________________________________ 
Control none none -- 
1 8,000 1 +15 
2 8,000 5 +40 
3 8,000 10 +51 
4 2,500 5 +45 
5 14,000 5 +40 
______________________________________ 
The above data shows that the incorporation of the oligomer segments into 
the fluoroelastomer according to this invention, provides a surface having 
improved release properties. Thus, the higher the contact angle, the lower 
the surface energy of the coating, and the better its surface release 
properties. 
The coatings prepared with the Control Composition and Compositions 1 and 2 
were also evaluated for toner release. This was done by placing 
approximately 0.5 grams of the yellow toner particles described in Example 
1 on the cured coatings prepared from the aforementioned three 
compositions. The toner particles were baked for one hour at 175.degree. 
C. (the fusing temperature of the particles), cooled and peeled from the 
coatings. The fused toner was much more difficult to peel from the coating 
prepared from the Control in comparison to those coatings prepared from 
Compositions 1 and 2. 
Although the invention has been described in detail with particular 
reference to certain preferred embodiments thereof, it should be 
appreciated that variations and modifications can be affected within the 
spirit and scope of the invention.