Process for fusing a toner image to a substrate using a wicking agent

A process for fusing a toner image to a substrate includes applying to a fuser member a replenishable layer containing a controlled amount of a wicking agent; the fuser member surface sites reactive to binding with Si--H functional groups included in an organopolysiloxane. The wicking agent have an organopolysiloxane having Si--H functional groups and at least about 1.times.10.sup.-6 weight percent of a metal compound that is effective for promoting reaction between the reactive sites on the fuser member surface and the Si--H functional groups of the organopolysiloxane. The toner image is contacted with a substrate at a temperature sufficient to fuse the toner image to the substrate.

FIELD OF THE INVENTION 
This invention relates in general to electrostatographic imaging and in 
particular to the fusing of toner images. More specifically, this 
invention relates to a process for fusing a toner image to a substrate by 
applying an improved wicking agent to a fuser member. 
BACKGROUND OF THE INVENTION 
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 receiver. The fusion step 
commonly involves directly contacting the substrate, such as a sheet of 
paper on which toner powder is distributed in an imagewise pattern, with a 
heated fuser member such as a fuser roller. 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 roller 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 fuser roller. Any toner remaining 
adhered to the heated surface can cause a false offset image to appear on 
the next sheet that contacts the fuser roller and can also degrade the 
fusing performance of the surface of the member fuser. 
To prevent toner offset, many expedients have been tried, for example, 
providing the fusing roller 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 wicking agents, e.g., 
polydiorganosiloxane compounds such as, for example, polydimethylsiloxane 
oils, have been applied to the fuser roller surface during the operation 
of the fusing member. U.S. Pat. Nos. 4,264,181 and 4,272,179 describe 
fuser rollers having surfaces comprising fluoroelastomers and 
metal-containing fillers and providing sites that react with 
functionalized polymeric wicking agents such as mercapto-functional 
polydiorganosiloxanes to form surfaces abhesive to toner materials, 
thereby reducing toner offset. Unfortunately, as such fuser rollers wear, 
fresh active sites that are exposed react not only with the functionalized 
polymeric agents but also with various components of the toner materials 
and the paper substrate. Such reaction builds up debris on the surface of 
the fuser roller, resulting in permanent damage to the surface and greatly 
reducing the life of the fuser roller. Additionally, the metal-containing 
filler particles are physically torn from the fuser surface during use, 
which also reduces the life of the fuser roll. Use of mercapto-functional 
polydiorganosiloxane wicking agents is also undesirable because of 
concerns relating to toxicity and unpleasant odors. 
U.S. Pat. Nos. 4,029,827, 4,101,686 and 4,185,140 also describe the use of 
functionalized polymeric wicking agents with heated fuser members. 
U.S. Pat. No. 5,401,570 discloses a fuser roller having a silicone rubber 
layer containing a filler component that reacts with a silicone hydride 
release oil. 
SUMMARY OF THE INVENTION 
In accordance with the invention, a process for fusing a toner image to a 
substrate comprises applying to a fuser member a replenishable layer 
containing a controlled amount of a wicking agent. The fuser member 
surface has sites that are reactive to binding with Si--H functional 
groups included in an organopolysiloxane. The wicking agent comprises an 
provides a wicking agent for application to a fuser member. The wicking 
agent comprises an organopolysiloxane having Si--H functional groups and 
at least about 1.times.10.sup.-6 weight percent of a metal compound that 
is effective for promoting reaction between the reactive sites on the 
fuser member surface and the Si--H functional groups of the 
organopolysiloxane. Pressure contacting a toner image with a substrate 
while heating fuses the toner image to the substrate. 
The metal compound promotes reaction between the Si--H functional groups of 
the organopolysiloxane and active sites on the surface of the fuser 
member. The reaction between the fuser member surface and the wicking 
agent organopolysiloxane improves the release performance of the fuser 
member, decreases toner offset, reduces wear, and extends the life of the 
fuser member while avoiding the odor problems associated with the use of 
mercapto-functionalized fluids. Further, unlike the prior art, it is not 
required to incorporate metal-containing fillers in the surface layer of 
the fuser member. 
DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A wicking agent is applied to fuser members present in the fusing system of 
an electrostatographic machine or the like. The wicking agent can be 
applied to the fuser member surface during copying, either continuously or 
discontinuously but preferably continuously, to provide a replenishable 
release layer to prevent toner offset and protect the surface layer of the 
fuser member. The preferred rate of application of the wicking agent to 
the fuser member is about 1 to 10 mg/copy, more preferably about 2 
mg/copy. 
The functionalized organopolysiloxane with Si--H functional groups included 
in the wicking agent of this invention can be represented by the formula: 
##STR1## 
wherein R.sup.1, R.sup.2, R.sup.3, R.sup.4, and R.sup.5, are independently 
selected from the group consisting of alkyl containing 1 to 10 carbon 
atoms, cycloalkyl containing 5 to 10 carbon atoms, alkoxy containing 1 to 
10 carbon atoms, and phenyl; R.sup.1, R.sup.2, R.sup.3, R.sup.4, and 
R.sup.5 are preferably alkyl containing 1 to 5 carbon atoms, most 
preferably methyl. A, B and C are independently selected from the group 
consisting of hydrogen, alkyl containing 1 to 10 carbon atoms, and alkoxy 
containing 1 to 10 carbon atoms, with the proviso that at least one of A, 
B or C is hydrogen, preferably, B being H and, more preferably, B being H 
and A and C each being alkyl. Also in the formula, m and n represent 
percentages, each in the range of 1 to 99 percent. 
Specific examples of commercially available Si--H functionalized 
polyorganosiloxanes of utility in this invention, all of which are 
available from Petrarch Systems, Bristol Pa., include: 
(1) polymethylhydrosiloxanes such as PS-119, PS-120 and PS-122; 
(2) hydride-terminated polydimethylsiloxanes such as PS-542, PS-543 and 
PS-545; and 
(3) organohydrosiloxane copolymers such as 
(a) PS-122.5, (50-55%)methylhydro-(45-50%)dimethylsiloxane, 
(b) PS-123, (30-35%)methylhydro-(65-70%)dimethylsiloxane, 
(c) PS-123.5, (15-18%)methylhydro-(82-85%)dimethylsiloxane, 
(d) PS-124.5, (3-4%)methylhydro-(96-97%) dimethylsiloxane, 
(e) PS-123.8, (0.5-1.0%)methylhydro-(99.0-99.5%)dimethylsiloxane, 
(f) PS-124, (40-60%)methylhydro-(40-60%)methylcyanopropylsiloxane, 
(g) PS-125, (40-60%)methylhydro-(40-60%)methyloctylsiloxane, 
(h) PS-125.5, (25-30%)methylhydro-(70-75%)methyloctylsiloxane, 
(i) PS-128, methyldimethoxy terminated methylhydrosiloxane, and 
(j) PS-129.5, dimethylsiloxy terminated (45-50%) 
methylhydro-(50-55%)phenyl-methylsiloxane. 
Preferred organopolysiloxanes include polymethylhydrosiloxanes and, more 
preferably, copolymers of at least two organohydrosiloxanes. 
The Si--H functional groups are preferably present at a concentration 
within the range from 0.1 to 60 mole percent, more preferably, within the 
range from 1 to 10 mole percent. The viscosity of the Si--H functionalized 
organopolysiloxane can range from about 20 to 200,000 centistokes at 
25.degree. C., preferably about 100 to 60,000 centistokes, and more 
preferably about 200 to 2000 centistokes. In carrying out the process of 
this invention, two or more Si--H functionalized organopolysiloxane fluids 
can be used in admixture so as to provide particular viscosity and Si--H 
content to meet the specific demands of the particular fusing system. 
Non-functionalized silicone fluids can also be blended with the Si--H 
functionalized organopolysiloxane fluids for the purposes of obtaining 
balanced physical properties, cost benefits, or both. 
The metal compound present in the wicking agent preferably comprises a 
metal salt, which may be complexed with an organic ligand. The metal is 
preferably selected from the group consisting of platinum, tin, zinc, and 
iron. Preferred metal salts include platinum perchlorate, platinum 
acetate, platinum octoate, tin perchlorate, tin acetate, tin octoate, zinc 
perchlorate, zinc acetate, zinc octoate, ferric perchlorate, ferric 
acetate, and ferric octoate, more preferably, platinum perchlorate, 
platinum acetate, platinum octoate, zinc octoate and tin octoate, and, 
most preferably, platinum perchlorate. Examples of useful organometallic 
complexes include platinum-divinyltetramethyldisiloxane complex, available 
from Petrarch Systems as Catalyst PC075, and 
platinum-cyclovinylmethylsiloxane complex, available from Petrarch Systems 
as Catalyst PC085. Examples of commercially available useful metal salts 
include zinc octoate, available from Petrarch Systems as Catalyst PC040, 
and tin octoate, available from Petrarch Systems as Catalyst PC050. As 
discussed in R. Anderson et al, Silicon Compound Register and Review, 
Petrarch Systems, 1987, pp 266-270, the disclosure of which is 
incorporated herein by reference, compounds of platinum, including 
organometallic complexes, are effective for promoting reaction between the 
Si--H groups of the organopolysiloxane included in the wicking agent and 
vinyl groups in the surface polymer of the fuser member. Metal compounds 
such as salts of iron, tin, and zinc are effective catalysts for the 
reaction of the organopolysiloxane Si--H groups with silanol groups on the 
fuser member surface. 
The affinity of the Si--H functionalized organopolysiloxane for the surface 
of the fuser member is substantially increased by incorporating the metal 
salt in the wicking agent at a concentration of at least about 
1.times.10.sup.-6 weight percent. Preferably, the amount of metal compound 
included in the wicking agent is about 2.times.10.sup.-6 to 
1.times.10.sup.-4 weight percent. 
The wicking agents of this invention can be applied to any fuser member 
surface. "Fuser member" is used herein to refer to components of an 
electrophotographic fusing system that engage a toner carrying receiver 
and fix the toner to the receiver by means of elevated temperature or 
pressure. Examples of fuser members include fuser and pressure rollers, 
fuser and pressure plates, and fuser belts. The term fuser member is also 
used herein to refer to similar components similarly employed in 
non-electrophotographic equipment. 
The fuser members typically comprise a support and a polymeric coating. The 
support can comprise metal, ceramic, or a polymeric material such as a 
thermoset resin, with or without fiber enforcement. The preferred fuser 
members are fuser and pressure rollers having a core for the support. The 
preferred core consists of a metal such as aluminum, nickel, or steel, 
most preferably, aluminum. The support can be coated with adhesion 
promoters, primers, and one or more polymeric layers. The fuser member 
polymeric surface material includes reactive sites such as, for example, 
hydroxyl and vinyl groups that undergo reaction with a Si--H functional 
group of an organopolysiloxane included in a wicking agent. Examples of 
materials that can be used to form the polymeric surface layers on the 
fuser members include fluoroelastomers, fluorosilicone rubbers, silicone 
rubbers, fluoropolymer resins, and interpenetrating networks of silicone 
polymers and fluoroelastomers. 
Silicone rubber layers may comprise polymethyl siloxanes, such as EC-4952, 
available from Emerson Cummings, and Silastic.TM. J or E, available from 
Dow Corning. Fluorosilicone rubber layers include 
polymethyltrifluoropropylsiloxanes, such as Sylon, Fluorosilicone FX11293, 
and FX11299, available from 3M. The polymer layer on the fuser member may 
also comprise an interpenetrating network containing separately 
cross-linked silicone polymer and fluoroelastomer. Interpenetrating 
networks are disclosed in U.S. application Ser. No. 08/122,754, filed Sep. 
16, 1993 as a continuation-in-part of U.S. application Ser. No. 
07/940,582, filed Sep. 4, 1992; and U.S. application Ser. No. 08/250,325, 
now U.S. Pat. No. 5,534,347, issued Jun. 9, 1996, which was filed May 27, 
1994 as a continuation-in-part of U.S. application Ser. No. 07/940,929, 
filed Sep. 4, 1992, the disclosures of all of which are incorporated 
herein by reference. 
The polymeric layer of the fuser member may comprise inert fillers or other 
addenda. Examples of useful fillers include particulate filler or pigments 
comprising, for example, metals such as tin and zinc, metal oxides such as 
aluminum oxide and tin oxide, metal hydroxides such as calcium hydroxide, 
silicates, carbon, and mixtures thereof. The filler can be present in the 
surface layer from 0 to about 50 percent of the total volume of the layer. 
In preferred embodiments of the invention, the surface layer contains no 
metallic fillers. 
The polymeric layer may be adhered to a metal component such as a core via 
a primer layer. The primer layer can comprise a primer composition that 
improves adhesion between the metal and the polymeric material. Primers 
for the application of fluoroelastomers, fluorosilicone rubbers and 
silicone rubbers to metal are known in the art. Such primer materials 
include silane coupling agents, which can be either epoxy-functionalized 
or amine-functionalized epoxy resins, benzoguanamine-formaldehyde resin 
crosslinker, epoxy cresol novolac, dianilinosulfone crosslinker, 
polyphenylene sulfide polyether sulfone, polyamide, polyimide and 
polyamideimide. Examples of commercially available primers for silicone 
rubbers and fluorosilicone rubbers include DC-1200, available from Dow 
Corning, and GE-4044, available from General Electric. Examples of 
commercially available primers for fluoroelastomers include Thixon 300 and 
Thixon 311, available from Morton Chemical Co. 
A preferred surface layer of the fuser member for the application of the 
wicking agent of this invention is a fluoroelastomer layer comprising a 
cured fluorocarbon random copolymer having subunits with the following 
general structures: 
##STR2## 
In these formulas, x, y, and z are mole percentages of the individual 
subunits relative to a total of the three subunits (x+y+z), referred to 
herein as "subunit mole percentages". (The curing agent can be considered 
to provide an additional "cure-site subunit", but the contribution of 
these cure-site subunits is not considered in subunit mole percentages.) 
In the preferred fluorocarbon copolymers, x is about 42 to 58 mole 
percent, y is about 26 to 44 mole percent, and z is about 5 to 22 mole 
percent. 
Preferred fluoroelastomers have subunit mole percentages in the ranges: x, 
from 47 to 56; y, from 21 to 39; z, from 10 to 22. More preferred 
materials have mole percentages in the ranges: x, from 50 to 55; y, from 
25 to 35; z, from 13 to 22. In the most preferred fluoroelastomers, x, y, 
and z are selected such that fluorine atoms represent between 69 and 74, 
more preferably, 70 to 72 percent of the total formula weight of the VF, 
HFP, and TFE subunits. The fluoroelastomer is preferably a terpolymer of 
VF, HFP, and TFE subunits, the weight ratio of vinylidene fluoride to 
hexafluoropropylene in the terpolymer being from 1.06 to 1.6. The uncured 
fluoroelastomer preferably has a number average molecular weight in the 
range of about 10,000 to 200,000. 
To form a fluoroelastomer layer, the uncured fluorocarbon polymer, 
crosslinking agent, and any other additives, for example, an accelerator 
or an acid acceptor type filler, are mixed to form a composite. The 
composite is applied over the support, with or without a base cushion 
layer, and cured. The crosslinking agent can be a basic nucleophile. Basic 
nucleophilic cure systems are well known and are discussed, for example, 
in U.S. Pat. No. 4,272,179, the disclosure of which is incorporated herein 
by reference. One example of such a cure system combines a bisphenol as 
the crosslinking agent and an organophosphonium salt, as an accelerator. 
Examples of bisphenol include 2,2-bis(4-hydroxyphenyl) hexafluoropropane, 
and 4,4-isopropylidenediphenol: 
##STR3## 
Examples of organophosphonium salts include halides such as benzyl 
triphenylphosphonium chloride: 
##STR4## 
The crosslinking agent is incorporated into the polymer as a cure-site 
subunit, for example, bisphenolic residues. Other examples of nucleophilic 
addition cure systems are sold commercially as DIAK No. 1 
(hexamethylenediamine carbamate) and DIAK No. 3 
(N,N'-dicinnamylidene-1,6-hexanediamine) by E. I. duPont de Nemours & Co. 
Nucleophilic addition-cure systems used in conjunction with fluorocarbon 
polymers can generate hydrogen fluoride, and thus acid acceptors are added 
as fillers. Suitable acid acceptors include Lewis bases such as metal 
oxides or hydroxides, for example, magnesium oxide, calcium hydroxide, 
lead oxide, copper oxide and the like. It is preferred to use 3 parts MgO 
and 6 parts Ca(OH).sub.2 per 100 parts of fluoroelastomer as acid 
acceptors in the fluoroelastomer layer composition. 
Other conventional cure or crosslinking systems containing free radical 
initiators may be used to cure fluoroelastomers, for example, organic 
peroxides such as dicumylperoxide and dichlorobenzoyl peroxide. 
2,5-Di-methyl-2,5-di-t-butylperoxyhexane with triallyl cyanurate may also 
be used; however, nucleophilic addition systems are preferred. 
Preferred solvents for the fluoroelastomer composites are the ketones, 
especially methyl ethyl ketone (MEK) and methyl isobutyl ketone. The 
preferred solvent is a blend of MEK and methanol, most preferably 85:15 by 
weight MEK:methanol. The composites are dispersed in the coating solvent 
at a concentration of between about 10 to 50 weight percent, preferably 
between about 20 to 30 weight percent, and coated on the fuser member to a 
thickness, after drying, of about 0.025 to 0.25 micron. The coated article 
is then cured. 
Curing of the fluoroelastomer layer is carried out according to the well 
known conditions for curing fluoroelastomers ranging, for example, from 
about 12 to 48 hours at temperatures between about 50.degree. C. and 
250.degree. C. Preferably, the coated fluoroelastomer layer is dried until 
solvent free at room temperature, then gradually heated to about 
230.degree. C. over 24 hours, and maintained at that temperature for 24 
hours. The thickness of the fluoroelastomer layer is preferably about 
0.025 to 0.25 micron if another polymeric layer is present on the support 
of the fuser member, and about 0.25 to 5 microns if the fluoroelastomer 
layer is applied to the support without the presence of another polymeric 
layer. 
The supports for the fuser members can be coated with the fluoroelastomer 
composite or other polymeric materials by conventional techniques, such as 
dip, spray, ring or blade coating. Coating solvents that can be used 
include polar solvents, for example, ketones, acetates and the like. 
Suitable uncured fluoroelastomers useful in this invention are available 
commercially. Fluorocarbon polymers useful for the surface layer include 
vinylidene fluoride-co-hexafluoropropylene-co-tetrafluoroethylene (x=52, 
y=34, z=14), available under the trade name Fluorel FX-9038 from Minnesota 
Mining and Manufacturing (3M), and vinylidene 
fluoride-co-hexafluoropropylene-co-tetrafluoroethylene (x=53, y=26, z=21), 
available under the trade name FE-5840Q from 3M. Other fluoroelastomers 
include VITON A and B, available from duPont, and Fluorel FX-2530, 
available from 3M. The wicking agent can be applied to a pretreated or 
untreated fuser member. The preferred pretreatment is described by Chen et 
al. in U.S. application Ser. No. 08/681,562 entitled, "Method of Fusing 
Heat Softenable Toner Images" filed Jul. 29, 1996, which is a 
continuation-in-part of U.S. application Ser. No. 08/216,200, having the 
same title, filed Mar. 22, 1994, abandoned, which is a 
continuation-in-part of U.S. application Ser. No. 07/919,669, having the 
same title, filed Jul. 27, 1992, abandoned, the disclosures of all of 
which are incorporated herein by reference. Prior to its installation in 
an electrostatographic machine, a fluoroelastomer outer layer of a fuser 
member is treated with a release agent that may have a composition the 
same as or similar to the wicking agent. The fuser member is then 
incubated, preferably for about 1 to 60 hours at a temperature of about 
100.degree. C. to 250.degree. C., more preferably for about 4 to 40 hours 
at about 125.degree. C. to 200.degree. C., and most preferably for about 8 
to 24 hours at about 160.degree. C. to 190.degree. C. 
In the electrostatographic machine, wicking agent is continuously or 
discontinuously applied to the pretreated fuser member. The wicking agent 
provides a replaceable layer that is at least partially removed by 
toner-bearing receivers as they pass through the fuser system to fix the 
toner to the receiver. The wicking agent is applied to at least one of the 
fuser members in the fusing system, preferably to the fuser roller that 
contacts the toner bearing side of the receiver. Any suitable method and 
devices known to a person of ordinary skill in the art can be used to 
apply the wicking agent to the fuser member. For example, wicking agent 
can be applied to the fuser member by oil donor rollers or rotating wick 
rollers and the like. The donor rollers can receive wicking agent from a 
metering roller, which in turn receives wicking agent from a wick or from 
a bath or reservoir of wicking agent. The amount of wicking agent supplied 
to the metering roller can be limited by a metering blade or by the 
characteristics of the wick. The wick can receive wicking agent from a 
wicking agent reservoir by capillary action or by the action of a pump. In 
alternative examples, the wicking agent can be supplied to the fuser 
member directly by a wicking roller. The preferred wicking roller has a 
wick that supplies wicking agent to a roller core that is permeable to the 
wicking agent. The preferred wick is a poly(methylphenylene isophtalate) 
NOMEX wick, available from DuPont. The wicking agent can also be supplied 
to the fuser member by pads or spraying devices. 
The wicking agent applied by the method of this invention preferably is 
present on the fuser member surface layer at a thickness of about 0.5 to 
40 nanometers (nm), more preferably about 2 to 15 nm, most preferably 
about 5 to 10 nm. 
The wicking agent present on the fuser member has a percentage atomic Si, 
as determined by X-ray photoelectron spectroscopy, of at least 10 percent, 
more preferably at least 15 percent, and most preferably at least 20 
percent. 
The wicking agent of this invention applied to fuser members is useful for 
fusing heat-softenable toner materials of all types having the physical 
properties required in dry electrostatographic toner materials. Such toner 
materials or particles can be thermally fixed or adhered to a receiver 
such as paper or plastic. These thermal fixing techniques are well known 
in the art. 
Many polymers have been reported in the literature as being useful in dry 
electrostatographic toners. Polymers useful in such toners include vinyl 
polymers, for example, homopolymers and copolymers of styrene, and 
condensation polymers such as polyesters and copolyesters. Fusible 
styrene-acrylic copolymers that are covalently lightly crosslinked with a 
divinyl compound such as divinylbenzene, as disclosed in the patent to 
Jadwin et al, U.S. Reissue Pat. No. 31,072, are useful. Also useful are 
polyesters of aromatic dicarboxylic acids with one or more aliphatic 
diols, such as polyesters of isophthalic or terephthalic acid with diols 
such as ethylene glycol, cyclohexanedimethanol 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 500.degree. C. to 2000.degree. C. so they can 
readily be fused to paper receivers. Preferred toners are fusible in the 
range of about 65.degree. C. to 120.degree. C. If the toner transfer is 
made to receivers that can withstand higher temperatures, polymers with 
higher fusing temperatures can be used. 
Toner particles can comprise simply the polymeric particles, but it is 
often desirable to incorporate addenda such as waxes, colorants, release 
agents, charge control agents, and other addenda well known in the art in 
the polymeric particles. 
Suitable colorants selected from a wide variety of dyes and pigments such 
as disclosed, for example, in U.S. Reissue Pat. No. 31,072 can be used. A 
particularly useful colorant for toners is carbon black. Colorants in the 
amount of about 1 to about 30 percent of the weight of the toner can be 
used. Preferably, about 1 to 8 weight percent 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; and 4,323,634; and in 
British Patent Nos. 1,501,065 and 1,420,839. Charge control agents are 
generally employed in small quantities, about 0.1 to about 3 percent, 
preferably about 0.2 to 1.5 percent, based on the weight of the toner. 
Toners 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, as disclosed, for 
example, in U.S. Pat. Nos. 3,850,663 and 3,970,571. Especially useful in 
magnetic brush development schemes are iron particles, for example, porous 
iron particles having oxidized surfaces, steel particles, and other "hard" 
or "soft" ferromagnetic materials such as gamma ferric oxides or ferrites, 
for example, 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 weight percent of toner 
particles and from 60 to 99 weight percent, by weight, of 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 microns, generally about 30 to 300 microns. 
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 microns, diameters of about 2 to 20 microns being 
particularly useful in many current copy machines. 
The invention is further illustrated by the following examples.

EXAMPLES 
The affinity of the wicking agents of this invention to heated fuser member 
surfaces in the process of the present invention can be assessed from the 
results of applying wicking agents comprising polyorganosiloxanes and 
metal compounds to a fuser member surface comprising, for example, a 
fluoroelastomer, incubating the fuser member for 8 hours at 170.degree. C. 
in contact with the wicking agent, and then subjecting the fluoroelastomer 
surface to repeated washings with dichloromethane to remove unreacted 
wicking agent. Quantitative measurements of the attachment of the 
polyorganosiloxane to the surface of the fluoroelastomer were carried out 
by X-ray photoelectron spectroscopy. 
The fluoroelastomer surface was a VITON A copolymer composition prepared as 
follows: One hundred parts of VITON A copolymer 
(copolyhexafluoropropylenevinylidene fluoride) having a number-average 
molecular weight of 100,000 (available from E. I. duPont & Co.), 20 parts 
of lead monoxide, 20 parts of carbon black (Stainless Thermax N 990 from 
R. T. Vanderbilt Co.), 6 parts of the cross-linking agent 
hexafluoroisopropylidenediphenol, and 2.5 parts of the cure accelerator 
triphenylbenzylphosphonium chloride were thoroughly compounded on a 
two-roll mill until a uniform and smooth sheet was obtained. Part of the 
sheet was cut into small pieces and dissolved in methyl ethyl ketone to 
form a 20% coating dispersion, which was hand-coated on a 2-mil stainless 
steel shim, air dried for 24 hours, ramped to 232.degree. C. over a 
24-hour period, and cured at 232.degree. C. for 24 hours. 
The coated stainless steel was cut into small pieces and a drop of wicking 
agent was applied to each piece and uniformly spread over the surface 
thereof. After incubation at 170.degree. C. for 8 hours, followed by 
washing with dichloromethane, the values for atomic percent silicon and 
atomic percent fluorine were determined by X-ray photoelectron 
spectroscopy. 
The results obtained are reported in Table I below which also describes the 
polyorganosiloxane fluid(s) used and the amount of metal compound included 
in the wicking agent. 
TABLE I 
______________________________________ 
(Metal 
Compound* 
Example Organopolysiloxane 
Weight %) % Si % F 
______________________________________ 
Control 1 
None 0 2.7 40.2 
Control 2 
Silicone Fluid DC-200** 
0 8.1 27.1 
Control 3 
Silicone Fluid F655B*** 
0 20.8 5.5 
Control 4 
PS-542 0 11.9 19.5 
Control 5 
PS-123.8 0 24.4 2.2 
Control 6 
PS-124.5 0 13.7 17.2 
1 PS-123.8 1.2 .times. 10.sup.-6 
24.9 1.6 
2 PS-123.8 6.0 .times. 10.sup.-7 
24.3 2.4 
3 PS-123.8 1.2 .times. 10.sup.-7 
24.0 3.1 
4 PS-124.5 1.2 .times. 10.sup.-6 
16.1 13.5 
5 PS-124.5 6.0 .times. 10.sup.-7 
13.3 17.9 
6 PS-124.5 1.2 .times. 10.sup.-7 
13.4 17.1 
______________________________________ 
*The metal compound was PC075, a platinum organometailic complex catalyst 
available from Petrarch Systems 
**Silicone Fluid DC200 is a nonfunctionalized trimethylsiloxaneterminated 
polydimethylsiloxane fluid available from DowCorning Chemical Co. 
***Silicone Fluid F655B is a mercaptofunctionalized polydimethylsiloxane 
(0.089% SH by weight) available from StaufferWacker Silicone Corp. 
For a surface totally covered with polydimethylsiloxane, the calculated 
percentage of atomic Si is 25%. Referring to Table I, the 
non-functionalized polyorganosiloxane DC-200 provided a percentage of 
atomic Si of only 8.1%. Use of the Si--H functionalized polyorganosiloxane 
PS-123.8 (M.sub.w 63,000, viscosity 10,000 cSt) with 1.2.times.10.sup.-6 
weight percent of metal compound provided an increase in the percentage of 
atomic Si from 24.4 to 24.9%, as shown by the results for Example 1 and 
Control 5 in Table 1. The mercapto-functionalized polyorganosiloxane 
F-655B provided a percentage atomic Si value of 20.8% (Control 3), but 
this material suffers from the disadvantages of unpleasant odor and 
toxicity, as previously described. Thus, results as good or better than 
those obtained with the mercapto-functionalized polyorganosiloxane can be 
obtained by use of a wicking agent comprising a Si--H functionalized 
polyorganosiloxane and a suitable metal compound, in accordance with the 
invention. 
The use of a reaction-promoting metal compound in the wicking agent is 
especially beneficial with lower molecular weight Si--H functionalized 
organopolysiloxanes. A substantial improvement in the Si percentage, 16.1% 
vs 13.3%, resulted when an effective amount of the metal compound catalyst 
was used with PS-124.5 fluid (M.sub.w 13,000, viscosity 250 cSt), as shown 
by the results for Example 4 and Control 6. The beneficial effect 
attainable with wicking agents containing low molecular weight, low 
viscosity organopolysiloxanes is important because it facilitates the 
pumping and metering of the wicking agent to the fuser member surface. 
The high affinity of Si--H functionalized organopolysiloxanes containing at 
least 1.times.10.sup.-6 weight percent of a reaction-promoting metal 
compound for fuser member surfaces provides excellent release of fused 
toner images. The process of the invention provides a highly effective way 
of meeting the need for excellent release characteristics without 
excessive wear of the fuser member and without encountering the problems 
of odor and toxicity associated with prior use of mercapto-functional 
polydiorganosiloxanes. 
The invention has been described in detail with particular reference to 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention.