Electrostatographic particulate toner and developer compositions

A toner composition comprised of resin particles, colorant material and an effect change controlling amount of at least one charge enhancing additive of the formula: ##STR1## wherein R.sub.1 and R.sub.2 are lower alkyl groups having 1 to 4 carbon atoms; R.sub.3 is a straight-chain alkylene group having from 1 to about 8 carbon atoms; and R.sub.4 is an alkyl group having from about 7 to about 24 carbon atoms. The toners of the present invention are resistant to smearing after fusing onto a suitable substrate, provide good adhesion of the fused image to the substrate, and provide uniform, stable, high net electrical charge on toner particles and work over a wide range of relative humidity.

The present invention relates to electrostatographic particulate toner and 
developer compositions. In particular, the present invention relates to 
electrostatographic particulate toner and developer compositions 
containing a specific class of charge control agents. 
Electrostatographic imaging processes have been described extensively in 
patents and other literature. These processes have in common the forming 
of an electrostatic charge pattern on an insulating photoconductor. The 
pattern, or latent electrostatic image, is made visible by contact with a 
developer containing electrostatically charged toner powder. Several 
methods of dry development are available, including the well-known 
magnetic brush and cascade development methods. 
Most dry developers are a mixture of toner particles and carrier particles. 
For magnetic brush development, the carrier particles can be a magnetic 
substance such as iron filings, powdered iron, or iron oxide. For cascade 
development and other methods, the carrier particles can be non-magnetic 
substances such as glass or ceramic beads. The toner particles become 
triboelectrically charged by frictional contact with the carrier 
particles. Then, when contacted with the oppositely charged image pattern 
on the photoconductor, they adhere to the charged area and make the image 
visible. In well-known office copying machines, the developed toner image 
is transferred from the photoconductor to a sheet of plain paper to which 
it is fixed by heat fusing or other known techniques. 
The major component of toners is usually a fusible polymeric material. A 
wide variety of fusible polymeric materials have been used as the polymer 
component of electrostatic toners. Such polymers include polystyrene, 
copolymers of styrene and a lower alkyl acrylate or methacrylate, 
polyesters and similar materials which can be heat-fused at temperatures 
generally above about 40.degree.C. Moreover, additives usually are 
dispersed in the polymer material. These additives can include one or more 
colorant agents such as pigments and dyestuffs which make the developed 
charge pattern visible. Also desirable as additives are ionic compounds 
which help to maintain a uniform, stable, high net electrical charge on 
the triboelectrically charged toner particles. These latter compounds are 
known as charge control agents or change enhancing additives. 
During the development step of an electrostatographic process, the toner 
particles become triboelectrically charged by frictional contact with the 
carrier particles. A charge control agent or charge enhancing additive 
improves the charge uniformity of a toner composition, that is, they 
insure that substantially all of the individual toner particles exhibit a 
triboelectric charge of the same sign (negative or positive) with respect 
to a given carrier; they increase the net electrical charge of the toner 
particles relative to a given carrier vehicle. 
Numerous charge enhancing additives have been proposed for 
electrostatographic toner compositions. For example, U.S. Pat. No. 
4,490,455, which issued to Hoffend, et al. on Dec. 25, 1984, teaches 
various amine acid salts such as stearyl dimethyl amine tosylate, lauryl 
dimethyl amine tosylate, and octyl dimethyl amine tosylate may be used as 
charge enhancing additives for toner compositions. 
U.S. patent No. 4,323,634, which issued to Jadwin on Apr. 6, 1982, teaches 
that quaternary ammonium salt surfactants comprising at least one amido 
group having 10 or more carbon atoms attached to the ammonium cation and 
an anion selected from a halide ion or an organosulfur-containing anion 
may be used as a charge control agent. 
U.S. Pat. No. 4,291,112, which issued to Lu on Sept. 22, 1981, teaches 
using colorant materials treated with a nitrogen-containing organic 
compound (i.e., quaternary ammonium salts, amines, amides, and alkyl 
pyridinium compounds) in toner compositions. The patent discloses that 
these nitrogen-containing organic compounds control both the polarity of 
charge as well as the magnitude of the charge of the toner. 
U.S. Pat. Nos. 4,683,188, and 4,780,553, which issued to Suzuki, et al. on 
July 28, 1987 and Oct. 29, 1988, respectively, teach that certain 
quaternary ammonium salts, having a molybdic acid anion, a tungstic acid 
anion, or a heteropolyacid anion containing molybdenum or tungsten atoms 
may be used as charge control agents for electrostatic toners. 
Other well-known charge control agents include nigrosine salts and organic 
salts such as cetyl pyridinium chloride and the like. 
It has been found that nigrosine salts when used as charge control agents 
in toners have the disadvantage of decreasing the adhesion of the toner 
particles to paper. 
Likewise, anionic charge control agents, such as those containing stearic 
acid moieties, do not impart a high net positive electrical charge to the 
toner particles when in the presence of the magnetic carrier particle. 
Also, non- surfactant, short-chain quaternary ammonium salts and 
alkoxylated amines, when used as charge control agents, provide high 
uniform net electrical charges, but are not as effective when the humidity 
of their operating environment is varied considerably. Still further, 
known charge control agents made from quaternary ammonium salts, having at 
least one long chain amido group attached to the ammonium cation, do 
maintain a high stable charge in a toner over a wide range of relative 
humidity; but the quantity of the charge with them depends upon the 
particular polymers or other ingredients also present in the toner 
composition. 
While these and other charge enhancing additives are suitable for their 
intended purposes, there still exists a need for toners containing a 
charge enhancing additive which maintain a uniform, stable high net 
electrical charge on toner particles without substantially adversely 
affecting adhesion of the toner to paper as well as being able to operate 
over a wide range of relative humidities. The present invention is 
believed to meet that need. 
Accordingly, the present invention provides for toner composition comprised 
of resin particles, colorant agent, and an effective charge controlling 
amount of at least one charge enhancing additive of the formula (I): 
##STR2## 
wherein R.sub.1 and R.sub.2 have lower alkyl groups having 1 to 4 carbon 
atoms; R.sub.3 is a straight-chain alkylene group from 1 to about 8 carbon 
atoms; and R.sub.4 is an alkyl group having from about 7 to about 24 
carbon atoms. 
The toners of the present invention may also contain other conventional 
toner components including plasticizers, lubricants, flow control agents, 
magnetic additives, additional charge control agents and like materials, 
and are adapted to be mixed with metallic or nonmetallic carrier particles 
to produce electrostatographic developer compositions. 
The toners of the present invention are resistant to smearing after fusion 
onto a suitable substrate, provide good adhesion of the fused image to the 
substrate, and provide a uniform, stable, high net electrical charge on 
toner particles and work over a wide range of relative humidity. 
The toner compositions of present invention contain three critical 
ingredients: at least one charge control agent of formula (I) above; at 
least one resin, and at least one colorant material. 
The preferred charge control agent agents of formula (I) are those where 
R.sub.1 and R.sub.2 are individually selected from either methyl or ethyl; 
R.sub.3 is a straight-chained alkylene having 2 to 5 carbon atoms; and 
R.sub.4 is an alkyl group having about 10 to 20 carbon atoms. The most 
preferred charge control agent agent within the scope of formula (I) is 
where R.sub.1 and R.sub.2 are both methyl; R.sub.3 is a trimethylene group 
(i.e., --CH.sub.2 --CH.sub.2 --) and R.sub.4 is a stearyl group (i.e., 
--C.sub.17 H.sub.35). This compound is known as stearylamidopropyl 
dimethylamine and is sold commerically as CYCLOMIDE SODI by Alcolac, Inc. 
of Baltimore, MD. This surfactant-type amine compound has previously been 
used as an emulsifier. 
In the toner compositions of the present invention, it has been found 
desirable to employ an amount of charge enhancing additive within the 
range of 0.01 to 5 weight percent and preferably 1 to 3 weight percent 
based on the total weight of the particulate toner composition. If much 
lower amounts are used, the charge control agent provides little or no 
effect. If much higher amounts are used, the net charge of the toner 
becomes unstable and is substantially reduced. The optimum amount will 
depend on the components selected for the particular toner composition and 
their respective amounts. 
The resin component of the toner compositions of the present invention is 
preferably a mixture of cross-linked vinyl aromatic copolymers, one of 
which has a gel content of greater than 15% up to about 50%, the other of 
which has a gel content of greater than 50% up to about 99%, said 
copolymers having respective gel contents which differ by at least about 
10% and said copolymers being present in a weight ratio with respect to 
one another ranging from about 10:90 to about 90:10. 
These preferred cross-linked polymeric material include copolymers and 
terpolymers containing at least about 40% by weight of one or more 
monovinyl aromatic compounds such as styrene; the halogenated styrenes 
such as mono- and dichlorostyrene; the alkyl styrenes such as the 
methylstyrenes, alpha-methyl styrene, dimethylstyrene, diethyl styrene, 
isopropyl styrene and the mixed alkylstyrenes; vinyl- naphthalenes; 
methylvinylnaphthalene, their halogenated derivatives, and mixtures of two 
or more of such monomers. 
In addition to the monovinyl aromatic monomer, these cross-linked 
copolymers and terpolymers preferably contain from about 5% to about 60% 
by weight of one or more vinylaryl or vinylalkyl acids or acid derivatives 
having vinyl or functional groups capable of undergoing covalent 
cross-linking with suitable cross-linking agents. Illustrative of such 
monomers are acrylic acid, and the alpha-alkyl substituted acrylic acids 
such as methacrylic acid, and esters of such acids with aliphatic 
alcohols; the amides of acrylic and methacrylic acids and derivatives 
thereof such as the methacrylamides, acrylamides, N-methylacrylamides, 
N,N-diethylacrylamide, N-ethylmethacrylamide, N,N-dimethylmethacrylamide; 
the nitriles such as acrylonitrile, methacrylonitrile, ethylacrylonitrile, 
chloroacrylonitrile, and other nitriles; the alkyl esters of 
alpha-ethylenic aliphatic dicarboxylic acids such as ethyl fumarate, ethyl 
maleate diethyl fumarate and diethyl itaconate; the unsaturated ketones, 
methyl vinyl ketone and methyl isopropenyl ketone, the vinylpyridines; the 
vinylquinolines; vinylfurane; vinylcarbazoles; the esters of vinyl 
alcohols such as vinyl acetate; acyl-amino substituted acrylic and 
methacrylic acids, the ethers of olefinic alcohols, especially the ethers 
of vinyl and allyl-type alcohols such as vinyl ethyl ether, vinyl butyl 
ether, vinyl tolyl ether, divinyl ether, methyl isopropenyl ether, 
methallyl ethyl ether, the unsaturated aldehydes such as acrolein and 
methacrolein; copolymerizable alkenyl chlorides including methallyl 
chloride, allyl chloride, vinyl chloride, vinylidene chloride, 
1-chloro-1-fluoroethylene, and 4-chlorobutene-1; and the vinylindenes. 
Typical copolymers and terpolymers which are especially useful in the 
present invention are prepared from blends of from about 40% to about 95% 
by weight styrene, from about 5% to about 60% by weight of acrylic or 
methacrylic acid or lower alkyl acrylates or methacrylates thereof having 
from 1 to about 4 carbon atoms in the alkyl moiety such as methyl, ethyl, 
isopropyl, butyl, and the like, or from about 5% to about 60% by weight of 
a higher alkyl acrylate or methacrylate having from about 6 to about 20 or 
more carbon atoms in the alkyl group such as ethylhexyl acrylate or 
methacrylate, or mixtures thereof. The most preferred copolymers are 
copolymers and terpolymers based on from about 50% to about 90% by weight 
vinyl aromatic monomer such as styrene and from about 10% to about 50% by 
weight of an acrylic or methacrylic monomer such as n-butyl acrylate, 
methyl methacrylate, n-butyl methacrylate, 2-ethylhexylacrylate, and 
mixtures thereof. 
The preferred vinyl aromatic copolymers used as the resin component of the 
present toners composition are cross-linked with a suitable cross-linking 
agent. The cross-linking agents useful for this invention include resinous 
cross-linkers such as melamine or urea formaldehyde resins or monomeric 
cross-linkers containing two or more ethylenically unsaturated groups such 
as divinylbenzene; allyl-containing compounds such as triallyl cyanurate 
and N,N-diallylmelamine; mixed allyl-vinyl compounds such as allyl 
acrylate, vinylidene compounds such as diethylene glycol diacrylate and 
ethylene glycol dimethacrylate; mixed allylvinylidene compounds such as 
allyl methacrylate; and mixed vinyl-vinylidene compounds such as mixed 
esters prepared from ethylene glycol and acrYlic and methacrylic acids. 
Other useful cross-linking compounds include the following: polyvinyl 
aromatic compounds, for example, divinylbenzene, divinyltoluene, 
divinylxylene, divinylethylbenzene, trivinylbenzene, divinylnaphthalene, 
divinYlmethylnaphthalenes; the cross-linking vinyl esters, allyl esters, 
and vinyl allyl esters of carboxylic and polycarboxylic acids including 
polymerizable ester monomers such as diallyl maleate, vinyl crotonate, 
divinyl succinate, divinyl adipate, vinyl acrylate, vinyl methacrylate; 
the aliphatic acetylenes such as vinylacetylene, and alpha-methyl 
vinylacetylene. 
The amount of cross-linking agent employed in the preferred cross-linked 
copolymer resins may vary substantially depending on the number of 
ethylenically unsaturated groups present in the compound, the reactivity 
of a specific cross-linking agent with a particular copolymer material, 
and the molecular weight of the particular cross-linking compound and 
copolymer material employed. Typically, amounts of cross-linking agent 
should be at least about 0.01 weight percent, preferably from about 0.01 
to about 5 weight percent, based on the total dry weight of the 
cross-linking agents blended with the copolymer binder materials. 
The copolymers may be prepared by any suitable process such as emulsion 
polymerization or a combination of emulsion and suspension polymerization 
such as disclosed in U.S. Pat. Nos. 3,938,992 and 4,652,511. Generally, 
the mixture of monomers and cross-linking agent or agents are dispersed 
into an aqueous medium containing an emulsifying agent, free radical 
catalyst such as azobisisobutyronitrile and a molecular weight regulating 
agent, and this mixture heated to about 60-90.degree.C. for a period of 
about 1 to 15 hours. Cross-linking normally occurs during polymerization. 
In suspension polymerization, an emulsion prepolymer prepared as above is 
dispersed in water, with or without the inclusion of additional monomer, 
using a dispersing agent such as hydrolyzed polyvinylalcohol or hydrolyzed 
polymethylmethyacrylate to hold the suspension, and polymerization 
continued. 
As indicated above, the toner of the present invention preferably contains 
a mixture of cross-linked vinyl aromatic copolymers prepared as described 
above, one of which has gel content of greater than 15 up to about 50% and 
the other of which has a gel content of greater than 50% up to about 99%. 
Preferably, the gel content of the vinyl aromatic copolymers differs by at 
least 10%, more preferably by at least 20%. Gel content may be controlled 
during polymerization largely as a function of the type and content of 
cross-linking agent used, initiator used, and the duration of the 
polymerization reaction, e.g., the higher the content of cross-linking 
agent and the longer the time of polymerization, generally, the higher the 
gel content. The skilled polymerization chemist can readily determine the 
degree of polymerization and the amount of cross-linking agent required to 
provide gel contents within the parameters herein given. In general, the 
molecular weight of the copolymers ranges from about 10,000 to 1,000,000 
as measured by gel permeation chromotography. 
The gel content of the copolymers is a ratio of the polymer portion which 
is insoluble in a solvent as a result of cross-linking and is defined as 
follows: 
##EQU1## 
wherein a sample of a particulate polymer (generally from 0.5 to 1 g.) is 
placed in an 80 mesh wire screen having a weight (W.sub.1) in grams and 
the total weight (polymer and screen) is established (W.sub.2) in grams, 
and then soaked in toluene at 20.degree.C. for 48 hours, followed by 
removal of the screen, drying and weighing (W.sub.3) the soaked polymer 
alone in grams. 
The most preferred cross-linked copolymers of the present invention have a 
softening temperature within the range of from about 40.degree.C. to about 
200.degree.C. so that the resultant toner particles can readily be fused 
to conventional receiving sheets to form a permanent image. Especially 
useful cross-linked binders are those having a softening temperature 
within the range of from about 40.degree.C. to about 65.degree.C. because 
toners containing these binders may be used in high speed electrographic 
copy machines employing plain paper as the receiving sheet to which the 
toned images are fused. Of course, where other types of receiving elements 
are used, for example, synthetic high melting point polymeric sheets, 
metallic sheets, and the like, cross-linked polymers having a softening 
temperature higher than the values specified may be used. 
As used herein the term "softening temperature" refers to the softening 
temperature of a polymer as measured by E.I. dupont de Nemours Model 941 
TMA (Thermal Mechanical Analyzer) apparatus using a probe pressure of 48 
p.s.i.a. and a heating rate of 5.degree.C./minute. 
The relative proportions in which the higher gel content and lower gel 
content copolymers of this invention are mixed generally ranges from about 
10:90 to 90:10, more preferably from 25:75 to 75:25 by weight. 
Suitable commercially available cross-linked vinyl aromatic polymer which 
may be used in the present invention are low gel copolymers of 80% by 
weight styrene and 20% by weight n-butyl acrylate such as are available 
from polytribo Corporation under the designations ZSR-1002 (25% gel), 
ZSR-1005 (25% gel), and ZSR-1007 (25% gel). An example of a higher gel 
copolymer useful for preparing the copolymer blends is Goodyear pliolite 
AC-4 which is composed of a terpolymer of 50 parts styrene, 30 parts butyl 
methacrylate, and 20 parts 2-ethylhexyl acrylate and has a gel content of 
90%. Other suitable higher gel content polymers include Hercules Res D-277 
and D-71, and other polymers such as disclosed in U.S. Pat. No. 4,806,635 
to the Hercules Corporation and Nippon ZEON S-111 and S-103. The latter 
resin is made from 75% by weight styrene, 20% by weight n-butyl acrylate, 
and 5% acrylonitrile and is cross-linked with divinylbenzene and has a gel 
content of about 70-90% by weight. 
Advantageously, these cross-linked fusible binder resins comprise 25% by 
weight or more of the toner particles used in the invention. In accordance 
with preferred embodiments of the invention where the toner particles of 
the invention are to be used in relatively high speed office copy devices, 
it has been found advantageous to use toner particles comprising at least 
50% by weight, and preferably 50-95% by weight of the cross-linked mixed 
polymer described above. 
A variety of colorant materials selected from dye-stuffs or pigments or 
both are advantageously employed in the toner materials of the present 
invention. Such materials serve to color the toner and/or render it more 
visible. The colorants used can, in principle, be selected from virtually 
any of the compounds mentioned in the Color Index, Volumes 1 and 2, Second 
Edition. 
Included among the vast number of useful colorants would be such materials 
as Hansa Yellow G (C.L. 11680), Nigrosine Spirit Soluble (C.I. 50415), 
Chromogen Black ETOO (C.I. 45170), Solvent Black 3 (C.I. 26150), Fuchsine 
N (C.I. 42510), C.I. Basic Blue 9 (C.I. 52015), and the like. Carbon black 
provides a particularly useful colorant. The amount of colorant added may 
vary over a wide range, for example, from about 1% to about 20% of the 
weight of the total toner. Particularly good results are obtained when the 
amount is from about 2% to about 10% by weight of the toner. 
When the toner of the present invention is to be used for Magnetic Image 
Character Recognition (MICR) applications, then finely divided magnetic 
particles such as gamma iron oxide or magnetite or ferrite materials may 
be included in the toner composition and at a level of from about 1% to 
about 60% by weight based on the total toner weight. Examples of suitable 
materials include commercially available acicular magnetites and cubical 
magnetites. Preferred magnetites are acicular magnetites such as available 
from pfizer under the designation MD 4131 and MO 4232, and cubical 
magnetites such as MO 7029, or circular magnetites from Magnox such as 
Magnox B-353. Other useful magnetites are Mapico Black available from 
Cities Service Company, and polyhedral magnetites available from Hercules 
Corporation as Ex 1601 and XMT 100. The preferred level of magnetite 
addition for the purposes of this invention is from about 10% to about 40% 
by weight based on the weight of the toner. 
The toner composition of this invention may also contain other polymeric 
components in addition to the cross-linked vinyl aromatic copolymers. 
Examples of such other polymeric components include smear inhibitors such 
as polyvinylbutyral resins and epoxy resins which tend to improve the 
smear resistant properties of the toner, and polymeric lubricants such as 
low molecular weight polyolefins, including oxidized and non-oxidized 
polyethylene or polypropylene which aid in the toners penetration of the 
substrate (e.g., paper). Other polymeric additives which may be included 
are silicone resins, polyvinylchloride, polyvinylacetate, polyesters, 
polyurethanes. polyamides, rosins, terpene resins, paraffin waxes, and the 
like. These classes of additives are generally each incorporated at a 
level of from about 0.05% to about 15% by weight, based on the total toner 
weight. 
The toner composition may also advantageously contain flow control agents 
such as polyvinylidene fluoride powder, or a finely divided silica or 
alumina powder. The silica fine powder may include anhydrous silicon 
dioxide and also silicates such as aluminum silicate, sodium silicate, 
potassium silicate, magnesium silicate, and zinc silicate. The amount of 
such flow control additives added to the toner composition generally 
ranges from about 0.5% to about 5.0% by weight, based on the total toner 
weight. 
A convenient method for preparing the toner is melt blending. This involves 
melting the binder polymer and mixing it with the colorant materials such 
as dyes or pigments and the other additives on heated compounding rolls. 
After thorough blending, the mixture is cooled and solidified. The solid 
mass is broken into small particles and finely ground to form a 
free-flowing power of toner particles which may then be further screened 
to remove large particles. 
Particles of mean diameter between 0.1 micron and 100 microns may be used, 
although present day office copying machines employ particles of mean 
diameter between 1 to 30 microns. Larger or smaller particles can be used 
for particular methods of development. For example, in powder cloud 
development, such as described in U.S. Pat. No. 2,691,345, extremely small 
toner particles can be used. 
The toners of this invention normally are mixed with a carrier to form a 
developer composition. In addition, magnetic carrier particles can be 
used. Suitable magnetic carrier materials include ferromagnetic materials 
such as iron, cobalt, nickel, alloys, and mixtures thereof, preferably 
steel shot. 
In developers for use in magnetic brush development, the carrier preferably 
comprises ferromagnetic particles overcoated with a thin or discontinuous 
layer of film-forming resin, for example, a fluorocarbon polymer such as 
polytetra- fluoroethylene, polyvinylidene fluoride, or a copolymer of 
vinylidene fluoride and tetrafluoroethylene or an alkali- soluble 
carboxylated polymer as described in Miller U.S. Pat. No. 3,547,822. Other 
useful resin-coated magnetic carrier particles are described in Miller 
U.S. Pat. No. 3,632,512, McCabe U.S. Pat. No. 3,795,617, and Kasper U.S. 
Pat. No. 3,795,618. preferably, the carrier comprises an iron or steel 
core which has been subjected to high temperature oxidation treatment in a 
fluidized bed as described in U.S. Pat. No. 3,767,477 to form a high 
resistant, durable, iron oxide layer thereon, followed by treatment of the 
resulting iron oxide-coated core in the bed with an inert atmosphere at 
elevated temperatures while a coating of a fluoropolymer layer is applied 
thereover. The resultant carrier may be preconditioned as described in 
Olsen, et al. U.S. Pat. No. 3,970,571, at least a portion of the toner 
removed and fresh toner added thereto before use. 
A typical developer composition containing the described toner and carrier 
particles comprises from about 1% to about 10% by weight of toner 
particles. The carrier particles can have a particle size of from about 30 
to about 1,200 microns, preferably 60-300 microns, and thus usually are 
larger than the toner particles. Developer compositions of the invention 
can also, however, employ smaller carrier particles, including those which 
are of about the same size as the toner particles, e.g., of 1 to 30 
microns average diameter. 
Developable charge patterns can be prepared by a number of well-known means 
and be carried, for example, on a light-sensitive photoconductive element 
or a nonlight sensitive dielectric-surfaced receiving element. Suitable 
dry development processes include cascading a developer composition across 
the electrostatic charge pattern as described in detail in U.S. Pat. Nos. 
2,618,551; 2,618,552; and 2,638,416. Another process involves applying 
toner particles from a magnetic brush developer composition as described 
in U.S. Pat. No. 3,003,462. Still another useful development process is 
powder-cloud development wherein a gaseous medium such as air is utilized 
as a carrier vehicle to transport the toner particles to the electrostatic 
charge pattern to be developed. This development process is more fully 
described in U.S. Pat. Nos. 2,691,345 and 2,725,304. Yet another 
development process is for brush development wherein the bristles of a 
brush are used to transport the toner particles to the electrostatic 
charge pattern to be developed. This development process is more fully 
described in Walkup, U.S. Pat. No. 3,251,706. 
As will be apparent from the above discussion, the improved electrographic 
development process of the present invention using the toner particles 
described herein can employ various types of carrier vehicles ranging from 
the conventional inorganic particles used in cascade development and 
metallic particles used in magnetic brush development to gaseous media and 
fur brushes used in powder cloud and fur brush development, respectively. 
After deposition of the toner particles in accordance with the process of 
the invention, the image can be fused as described earlier herein to 
adhere it to the substrate bearing the toner image. Radiant heaters or 
heated fuser rolls may be employed to provide fusion heat. If desired, the 
unfused image can be transferred to another support such as a blank sheet 
of copy paper and then fused to form a permanent image thereon. 
The following examples are included for a further understanding of this 
invention. All parts and percentages are by weight unless explicitly 
stated otherwise.

EXAMPLE 
PREATION OF TONER 
The following dry ingredients were premixed in a container: 
______________________________________ 
Ingredients Parts by Weight 
______________________________________ 
80% Styrene/20% Butyl Acrylate 
41.0 
Copolymer (20-30% gel content).sup.1 
75% Styrene/20% Butyl Acrylate 5% 
41.0 
Acrylonitrile Copolymer 
(70-90% gel content).sup.2 
Carbon Black.sup.3 7.5 
Polypropylene (nonoxidized).sup.4 
3.0 
Polypropylene (oxidized).sup.5 
1.0 
Epoxy Resin.sup.6 4.0 
Stearylamidopropyl Dimethylamine.sup.7 
2.5 
100.0 
______________________________________ 
.sup.1 ACRYBASE ZSR1005 available from Polytribo, Inc. of Philadelphia, 
PA. 
.sup.2 S103 available from Nippon Zeon Co., Ltd. of Tokyo, Japan. 
.sup.3 Regal 330R available from Cabot Corp. of Boston, Ma. 
.sup.4 Viscol 550P available from Sanyo Chemical Industries, Ltd., of 
Kyoto, Japan. 
.sup.5 Viscol TS200 available from Sanyo Chemical Industries, Ltd. of 
Kyoto, Japan. 
.sup.6 EPON 1007F available from Shell Oil Company of Houston, TX. 
.sup.7 CYCLOMIDE SODI available from Alcolac Inc. of Baltimore, MD. 
After the ingredients were thoroughly mixed, the mixture was added to a 
Banbury mixer and compounded therein for about 5 minutes. During this 
compounding, the mixture temperature raised up to 
200.degree.F.-250.degree.F. because of the shearing forces in the mixer. 
After this Banbury compounding step, the resulting molten mixture was added 
to a two-roll mill for further mixing. The mixture was passed through the 
two-roll mill ten times at a gap setting of 35 mils. The resulting 
slab-like mixture was then cooled to room temperature and then 
coarse-crushed by passing through a Fitz mill. This was followed by 
further pulverization by passing through a Sturtevant micronizer and 
Donaldson Classifier Acucut Model A-12. The resulting toner sample had its 
particle size distribution measured in a Coulter Counter. The measured 
mean particle size was 7.97 microns. The toner contained 12.2% by number 
of particles smaller than 5.04 microns and 1.8% by number of particles 
greater than 20.2 microns. 
PREATION OF DEVELOPER 
Three parts of the above toner were mixed with 100 parts by weight of an 
oxidized Hoeganaes EH sponge iron particles (particle size range of 
100-200 microns) coated with KYNAR fluorocarbon resin in a Twin Shell 
Blender for 15 minutes. Then the resulting developer was machine print 
tested in a Siemens 2200 laser printer having a floating development 
station. Before and during this machine testing, the resistance (ohm), 
Tribo (.mu.C/g) and toner concentration in the developer (% by weight) 
were measured. These results are shown in Table I below. 
MACHINE TESTING RESULTS 
The resistance data shown below is the developer nip resistance measured in 
this laser printer by using a stationary electrode on the bare aluminum 
developer drum in the printer. The developer nip resistance should stay 
relatively stable through the operation of the printer. If the developer 
nip resistance varies considerably, an undesirable background will appear 
in the printed image or the printed image will appear less dense. The 
"relative stable resistance" will vary from printer-to-printer. For the 
Siemens 2200 laser printer, the variance of resistance should be less than 
1.4 units (i.e., log of the maximum operating resistance minus the log of 
the minimum operating resistance should be less than 1.4). 
Tribo (or Q/M or triboelectric charge per mass) is the measure of the 
charge remaining on a toner particle after being activated by a carrier 
particle. Tribo was measured by the Faraday Cage "blow-off" technique as 
described in U.S. Pat. No. 3,526,533. Most laser printers have a Tribo 
operating window of from about -10 to about -30 .mu.C/gram of toner at a 
toner concentration range from about 1-3% by weight. 
TABLE I 
______________________________________ 
Resistance Tribo Toner Conc. 
Print Count 
(Ohm) (.mu.C/g) 
(% by Weight) 
______________________________________ 
1 3.88 .times. 10.sup.6 
-37.7 2.66 
18,000 1.34 .times. 10.sup.6 
-29.2 2.68 
30,000 1.33 .times. 10.sup.6 
-26.2 2.78 
45,000 1.4 .times. 10.sup.6 
-28.5 2.76 
60,000 1.2 .times. 10.sup.6 
-22.3 2.88 
75,000 1.53 .times. 10.sup.6 
-23.1 2.70 
90,000 1.9 .times. 10.sup.6 
-25.2 2.68 
120,000 2.82 .times. 10.sup.6 
-24.2 2.99 
150,000 4.46 .times. 10.sup.6 
-20.3 2.76 
______________________________________ 
These results indicate that developer resistance and Tribo were relatively 
stable during a machine test of 150,000 print copies made on this 
particular laser printer. Specifically, the resistance varied only 0.57 
units (i.e., log of 4.46.times.10.sup.6 minus log of 1.2.times.10.sup.6 
=6.65-6.08=0.57). Also, the Tribo varied only -29.2 to -20.3 .mu.C./gram 
since the initial -37.7 .mu.C./gram measurement may be disregarded as 
being part of the run-in period for this printer. 
These test results were also in the same range of resistance and Tribo 
values for a similar developer containing the same percentages of the 
above-noted toner ingredients, except for the charge control agent. That 
similar developer instead employed Hodogaya TP-415 as the charge control 
agent. 
While the invention has been described above with reference to specific 
embodiments thereof, it is apparent that many changes, modifications and 
variations can be made without departing from the inventive concept 
disclosed herein. Accordingly, it is intended to embrace all such changes, 
modifications and variations that fall within the spirit and broad scope 
of the appended claims. All patent applications, patents and other 
publications cited herein are incorporated by reference in their entirety.