Note: Descriptions are shown in the official language in which they were submitted.
6~
APPARATUS, PROCESS FOR CHARGIN~ INSULATING TON~R PARTICLES
BACKGRC)UND OF THE INVENTION
This invention is generally directed to an irnproved apparatus, and
an improved process for charging insulating toner particles. More specifically,
the present invention is direeted to an improved apparatus for charging
insulating toner particles to an appropriate charge level, and a desired charge
polarity~ that is, either positive or negative, utilizing a charge injecting
electrode. The resulting charged toner particles can be utilized as single
component developers, that is, developers containing no carrier particles, for
developing images in electrostatographic imaging systems.
The formation and development of electrostatographic images, and
more specifically xerographic images, is well known in the art as described for
example in U. S. Patent 2,297,691. In one known method for causing the
development of such images, a developer composition comprised of toner
particles and carrier particles is cascaded over an image bearing member,
wherein the toner particles which are triboelec~rically charged to a certain
polarity and magnitude deposit in regions of the imaging surface where there
is a preponderence of charge of opposite polarity. In another form of
development known as magnetic brush development, magnetic carriers are
employed, reference IJ. S. Patent 3,641,980, ~vherein magnetic forces are
employed for the purpose of causing toner particles to deposit on the imaging
member. In addition to providing for the superior development of solid image
areas, magnetic brush development systems are more compact than cascade
development systems, and do not depend on gravity for causing the toner
particles to deposit on the imaging member surface, a factor which allows
more freedom in locating the developer station.
In developer mixtures used in conventional cascade development
systems, there is a triboelectric charging relationship between the toner
particles and the carrier particles, thus ~or example, the toner particles are
charged negatively, and the carrier particles are charged positively, accord-
ingly, positively and negatively charged images cannot easily be rendered
visible with the same developer. Also, the triboelectric properties of the
toner composition while necessary for development can cause problerns, for
example, uneven charging of the toner causes background deposits, as the
forces between the carrier and toner particles result in various threshold
--2--
levels from toner particle to toner particle. Further, since the toner particlesretain their charge for extended periods of time, any toner that escapes the
development ~one and enters into other parts of the electrostatographic
apparatus can eause mechanical problems. While magnetic brush development
5 overcomes some of the problems encountered with cascade development, it is
in some instances less efficient in that it requires triboelectrically charged
toners.
There has also been described in the prior art magnetic develop-
ment systems and materials wherein carrier particles are not utilized, that is,
one component developer compositions. One such system is described in U. S.
Patent 2,846,333, which patent diseloses the use of a magnetic brush to apply
toner particles formed of magnetite and resin materials. One difficulty
encountered with this process is that the relatively high electrical con-
ductivity of the toner partieles renders electrostatic transfer rather difficult.
15 ~lso there is described in U. S. 3,909,258 electrostatic development utili~ing
magnetic brush and no carier particles. The developing composition used in
such systems is comprised of toner particles, reference U.S. 3,639,245. One
d;sadvantage of such a toner composition is that it does not transfer
efficiently from a photoconductive substrate to plain bond paper.
Most single component development systerns eontrol background
deposition with magnetic forces, and as such forces are generally weaker than
eleetrostatic forces, background development from single component systerns
is typically inferior to electrosta$ic systems employing two component
developer compositions. Additionally, many single component development
25 systems use conductive toner eharged by induetion, however, conductive toner
usually requires special papers and the like.
The utilization of insulating toner particles is thus important for
background control, and also such particles can be transferred rather
efficiently and effeetively from a photoresponsive surface to plain paper.
30 While many different suitable methods are known for eharging toner particles,there continues tc be a need for an effective simple method for charging
insulati7re toner particles, to a desired charge magnitude and a desired positive
or negative charge polarity.
Other development methods include powder cloud development as
35 described in U. S. Patent 2,217,776 and touchdown development as described inU. S. Patent 3,166,432. In the '432 patent there is disclosed the use of a
3r7i5i
--3--
conductive c~ne component developer (toner and no carrier
particles) for developing electrostatic charge patterns by
bringing a conductive support member containing a layer of
conductive toner particles into contact with the charge
pattern. The toner particles are held to the support
member primarily by Vander Waals forces, and the conductive
support is maintained at a biased potential during develop-
ment.
SUMMARY OF THE lNv~NllON
It is a feature of an aspect of the present inven-
tion to provide an apparatus and process for charging
insulative toner particles.
A feature of an aspect of the present invention
is the provision of an improved apparatus and improved
process for charging insulative uncharged toner particles
utilizing a charging electrode~
A feature of an aspect of the present invention is
the provision of a process for charging uncharged toner
particles to a positive polarity, or a negative polarity.
2Q A feature of an aspect of the present invention is
the provision of a process for charging insulative tone;
particles while simultaneously controlling background
drvelopment7 and providing for the efficient and ef~ectjve
transfer of such toner particles from an image bearing
surface to plain paper.
These and ot~er ~eatures o~ the present invention
are general~y accomplished by the provision o~ an improved
process and an improved apparatus for charging insulating
toner particles, which comprises providing in operative
relationship ~ ton~r supply means, a roller means contain-
ing thereon uncharged insulating toner particles, a
charge injection means in close proximity to the roller
means~ and self-spaced from said roller means by insulating
toner particles, a voltage means or the charge injection
~4--
means, and a voltage means for the roller means. The
roller means generally contains a coating thereon as indi-
cated hereinO
In one embodim~nt, the presen~ invention is direct-
ed to an improved apparatus for charging uncharged insulating toner particles, which apparatus comprises in operative
relationship a roller means containing a coating thereon, a
toner supply means containing therein uncharged insulating
toner particles, a charge injecting means, a voltage source
means for the charge injecting means, and a voltage source
means for the roller means, wherein charges are injected
from the charge injecting means into the uncharged insula-
ting toner particles deposited on the roller means, the
injection being accomplished in a charging zone encompassed
by the roller means and the charge injecting means.
In another embodiment the pre~ent invention is
directed to a process for charging insulating uncharged
toner particles contained on a roller means, to a positive
or negative polarity by injecting the appropriate charges
thereon, or therein from charges originating from a charge
injecting electrode means which contacts toner particles
contained in a zone between the roller means and the
electrode means, the polarity of the charges contained on
the insulating toner particles being dependent on the
polarity of the charges supplied to the charging electrode
by a voltage source means. The thus charged insulating
toner particles can be employed in electrostatographic
imaging systemsr particularly xerographic imaging systems.
Accord_ngly, in accordance with the process o~ the present
invention and the apparatus thereof, toner particles can
be charged to the desired polarity without the utilization
of carrier particles as is customarily practiced in the
prior art.
-4a~
In accordance with another feature of the present
invention, there is provided an improved electrostato-
graphic imaging apparatus comprising a charging means, an
imaging means, a development means, a transfer means, a
fusing means, an optical cleaning means and a fixing
means, the improvement residing in the development means
which comprise in operative relationship a roller means,
containing a coating thereon, a toner supply means contain-
ing therein uncharged insulating toner particles, a charge
injecting means, a voltage sou.rce means~ for said charge
injecting means, a voltage source means for said roller
means, wherein charges are injected from said charge inject-
ing means into the uncharged insulating toner particles
deposited on said roller means, said injection accomplished
in a charging zone encompassed by said roller means and
said charge injecting means, and wherein the resulting
charged insulating toner particles are deposited on an
imaging member.
Other aspects of this invention are as follows:
An improved apparatus for charying uncharged insu-
lating toner particles which apparatus comprises an opera-
tive relationship a roller means containing a coating
thereon, a toner supply means containing therein uncharged
insulating toner particles, a charge injecting means, a
voltage source means for said charge injecting means, a
voltage source means for said roller means, wherein charges
are injected from said charge injecting means into the un-
charged insulating toner particles deposited on said roller
means, said injection accomplished in a charging zone encom-
passed by said roller means and said charge injecting meansO
An improved electrostatographic imaging apparatuscomprising a charging means, an imaging means, a develop-
ment means, a tranfer means., a fusing means, and a fixing
means, the improvement residing in the development means
r
-~b-
which comprises in operative relationship a roller means
containing a coating thereon, a toner supply means con^tain~
ing therein uncharged insulating toner particles, a charge
injecting means, a voltage source means for said charge
injecting means, and a voltage source means for said roller
means, wherein charges are injected from said charge inject-
ing means into uncharged insulating toner particles deposit-
ed on said roller means, said injection accomplished in a
charging 7one encompassed b~ said roller means and said
charge injecting means, and wherein the resulting charged
insulating toner particles are deposited on an imaging
member contained in said imaging apparatus.
An improved process for charging ~mcharged insula-
ting toner particles which comprises providing uncharged
insulating toner particles on a roller con~aining a coating
thereon, contacting said toner particles with a charge
injecting electrode, in a charging ~one encompassed by said
roller and said injecting electrode, providing a voltage
source for said charge injecting electrode, and providing
a voltage source for said rollerJ whc~rein charges are
injected into the uncharged insulating toner particles.
An improved apparatus ~or charging insulating
toner particles comprised in operative relationship of a
means for transporting insulating toner particles, and a
means for injecting charges into the insulating toner
particles, the means for transporting and the means for
injecting being charged to a predetermined potential.
An improved electrostatographic imaging apparatus
comprising a charging means, an imaging means~ a develop-
ment means, a trans~er meansr a ~using means7 and a fixingmeans, the improvement residing in the development means
which comprises in operative relationship a means for
transporting insulating toner particles, and a means for
~ ! \
s
~4c~
injecting charges into the insulating toner particles, the
means for transporting and the means for injecting being
charged to a predetermined potential, wherein the result-
ing charged insulating toner particles are deposited on an
imaging member contained in said imaging apparatus.
An improved process for charging insulating toner
particles which comprises providing uncharged insulating
toner particles on a transporting means, contacting said
insulating toner particles with a means for injecting
charges into the insulating toner paxticlesr the means for
transporting and 1-he means for injecting being charged to
a predetermined potential r wherein charges are injected
into the uncharged insulating toner particles.
DEgCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention and various alternative
embodiments thereof will now be described with reference
to the Figures wherein:
Figure l is an elevational view illustrating the
development apparatus and development process of the
present invention.
Figure 2 illustrates t~e use of the apparatus and
process of the present invention in a conventional electro-
statographic imaging system.
.,., .
., ,, ~ .
7~S
--5--
Illustrated in Figure 1 is the apparatlls and process of the present
invention generally designated 7 comprising an imaging member means 10, a
roller means 12, containing thereon coating 13, toner supply reservoir means 14,containing therein uncharged insulating toner particles 24, a charging
electrode means 16, a pressure blade means 17, a voltage source means 18, a
voltage source means 20, and charging zone 19. The uncharged insulating toner
particles 24 are metered onto the roller means 12 as the roll moves in the
direction illlJstrated by the arrow, the amount of toner partieles being
depos;ted on said roll dependent primarily on the spacing between the toner
supply reservoir 14 and roller 12. ~he toner supply resersloir thus functions
similar to a doctor blade and is maintained at a specific angle and at a
sufficient pressure so as to provide uncharged insulating toner particles on theroller means 12 in a thickness of from about 0.5 mils to about 2 mils, and
preferably from about 0.5 mils to about 1 mil, or preferably about 1 layer of
toner particles. The insulating toner particles are adhered to the roller means
12 by electrostatic attraction forces, the roller being caused to rotate by a
motor not shown. As the insulating toner particles 24 migrate on the roller
means 12, they eventually contact the charge injecting electrode means 16 in
charging zone 19 wherein charges of a positive polarity as illustrated, or a
2~ negative polarity not illustrated, are injeeted into the toner particles;
accordingly, the toner partieles exiting from the charging zone 19 contain
thereon positive charges 24'. The charging electrode means 16 is self-spaced
from the roller means 12 by the toner particles situated therebetween, and the
voltage source, 18, Vc, supplies the charge to the electrode 16, which charge inthe embodiment shown is of a positive polarity. The positively charged toner
particles continue to migrate on the roller means 12~ until they contact the
latent image contained on the imaging member means 10, wherein they are
electrostatically attracted to the image, causing development. Unused
charged toner particles are returned to the toner supply reservoir 14 on the
roller means 12 as shown. The doctor blade 17 provides sufficient pressure to
the imaging member means 10 so as to cause said imaging mermber means to be
in constant contact with the charged insulating toner particles as shown.
Voltage, 20, VB, also assists in providing for attraction between the charged
toner particles and the image contained on the imaging member 10.
An important feature of the present invention resides in the
charging electrode means 16, which electrode injects positive charges, or
--6--
negative charges into the insulating toner particles 24 contained on the roller
means 12. The polarity of the charge, and the magnitude of charge injected is
controlled by the voltage source Vc 18, thus if a positive polarity is desired on
the toner particles, a positive voltage source is applied to the inJecting
5 contact means 16, while if a negative polarity is desired on the insulating toner
particles, a negative voltage Vc is applied to the charging electrode means 16.
Charges of the appropriate polarity and magnitude are injected into and
accepted by the insulating toner particles as a result of the contact between
such particles and the injecting electrode means 16, which is self-spaced from
10 the roller means 1~ by the insulating toner particles situated in the charging
zone 19. As indicated herein, generally only one layer of toner particles is
contained on the roller means 12, although less or more than one layer of toner
particles can be present on rol1er 12, however, if several layers of uncharged
toner particles are contained on the roller means 12, difficulties can be
15 encountered in completely charging all the layers of toner particles, since the
charge being injected by the electrode 16 cannot usually penetrate more than a
few layers of toner particles. The resulting charged insulating toner particles
can easily be transferred to plain bond paper subsequent to development as
contrasted with conductive toner particles which contain conducting agents
20 therein, and are very difficult to transfer to plain bond paper.
The roller means 12 is comprised of a core which can be hollow or
solid and is comprised of numerous known suitable materials including for
example, aluminum, steel, iron, polymeric materials, ~md the like~ providing
they are of sufficient strength to be operable in the system, with the preferred25 core material being aluminum. (~enerally, this roll has a diameter of from
about 1 inch to about 3 inches and preferably has a diameter of from 1 inch to 2inches. This roll can be of a larger or small diameter providing it accom-
plishes the objectives of the present invention.
The roller means 12 contains thereon a resistive textured coating
30 layer 13 such as aluminized ~aylar overcoated with carbon black, Krylo~ultra
flat black paint, commercially available as Krylon 1602, and various other
similar resistive materials. The thiclcness of the coatin@; can vary over a widerange and is dependent on many factors including economical considerations,
however, generally the thickness of this coating is from about 0.1 mils to about35 5 mils and preferably is from about 1 mil to about 3 mils. While it is not
desired to be limited by theory~ it is believed that the coating assists in
c~ rk5
~a~
--7--
increasing the efficiency of charge injection from the charge injecting
electrode 16, in that for example, negative charges, which would tend to
neutrali~e the positive charges of the charged toner particles contained on the
charging roll 12 are prevented from being attracted to the positively charged
5 toner particles. Similarly, when a negative charge is injected into the
insulating toner particles, a corresponding positive charge results on the roller
means 12, and it is desired to prevent such a charge from migrating to the
negatively charged toner particles.
The amount of charge applied to the uncharged insulating toner
10 particles is primarily dependent on the voltage source 18 Vc, which charge
generally ranges from about lûO volts to about 500 volts3 and preferably from
about 200 volts to about 300 volts when a positive polarity is desired on the
insulating uncharged toner particles. When a negative polarity is desired on
the uncharged insulating toner particles, the voltage Vc 18 is from about a -10015 volts to about a-500 volts, and preferably erom about a -200 volts to about a -300 volts.
The charge injected into the uncharged toner particles is not onl~J
dependent on the voltage source 18 Vc but on a number of other factors
including for e~ample, the number of layers of particles charged, the material
20 utilized as coating 13, and the like. lIowever, generally the uncharged tonerparticles acquire a charge of from about 10 microcoulombs per ~ram to about
35 microcoulombs per gram, and preferably from about 11) microcoulombs per
gram to about 20 microcoulombs per gram. Such toner particles are thus of
sufficient conductivity so as to be attracted to the image contained on the
25 imaging member means 10, but yet sufficiently insulating in order that they
may be easily transferable to plain bond paper.
The voltage source 20, VB, which is primarily employed for
background control in the image areas in that it prevents deposition of the
charged insulating toner particles in the background areas ranges from about
30 -75 volts to about -200 volts and preferably ranges from about a -75 volts to about a -150 volts.
The injecting eleetrode means 16 can be comprised of various
suitable materials providing it is capable Oe accepting charge from the voltage
source 18 Vc, and furthera such electrode means 16 should be comprised of a
35 material that will enable the injection of positive or negative charges erom the
injecting source means 16 into the uncharged insulating toner particles in
7~i5
--8--
accordance with the features of the present invention. C~enerally, the
injecting or ~harging electrode can be comprised of metallic substances such
as aluminum, steel, iron and the like, with aluminum being preferred. The
eharging electrode means 16 is usually not maintained in a fixed position,
5 rather it generally contains thereon a foam backing which is not shown7 so as
to allow it to contact the roller means 12, which contact is usually prevented
by the layer of insulating uncharged toner particles contained between the
charge injecting means 16 and the roller means 12. Thus, the charging
electrode means 16 is self-spaced from the roller means 12, such self-spacing
10 being dependent on the number of layers of toner particles contained in the
charging zone l9. The length of the charging zone 19 ean vary providing the
objectives of the present invention are accomplished, generally however, this
length is from about 5 millimeters to about 30 millimeters9 and preferably
from about lD millimeters to about 20 millimeters.
The direction of movement of the roller means 12 and the imaging
member means 10 can be as shown, that is, in the same direction, or in a
dire~tion opposite to each other, that is, roUer 12 can move in the direction
opposite to that of the direction of movement of imaging member means 10.
~enerally, roller means 12 is moving at a rate o speed that is faster than the
20 rate of speed OI movement of the irnaging member means 10, thus the speed
ratio of the charging roll 12 to the imaging member means 10 varies from about
4 to about 1 and is preferably from about 2 to about 3. Accordingly thus, in
this embodiment, the roller 12 is moving at a higher speed (d~) than the speed of
the imaging member means 11~.
The pressure blade 17 can be comprised of numerous suitable
materials including plastics, nylon, steel, aluminum and the like with the forcebeing exerted by such blade being of sufficient value so as to maintain the
imaging member 10 in contact with the charged insulflting toner particles, such
force ranging generally from about 0.3 pounds per inch to about 3 pounds per
30 inch and preferably from about 0.5 pounds per inch to about 1 pound per inch.The process and apparatus of the present invention can be utilized
in various imaging systems including electrostatic latent imaging systems as
shown for example in Figure 2. In Figure 2 there is illustrate~ a xerographic
imaging system employing an imaging member 1, which corresponds to the
35 imaging member 10 of Figure 1. In this embodiment of the present invention
the imaging member 1 can be comprised of a substrate, overcoated with a
3r7~j
_9_
transport layer containing N,~,N',N'-tetraphenyl-[l,lt-biphenyl] ~4'-diamine,
or similar diamines dispersed in a polycarbonate, which in turn is overcoated
with a generating layer of trigonal selenium. Imaging member 1 moves in the
direction of arrow 27 to advance successive portions of the imaging member
5 sequentially through the various processing stations disposed about the path of
movement thereof. The imaging member is entrained about a sheet-stripping
roller 2~, tensioning means 29, and drive roller 30. Tensioning means 29
includes a roller 31 having Ilanges on opposite sides thereo~ to define a path
through which member 1 moves, with roller 31 being mounted on each end of
10 guides attached to springs. Spring 32 is tensioned such that roller 31 presses
against the imaging belt member 1. In this manner, member 1 is placed under
the desired tension. The level of tension is relatively low permitting member 1
to be easily deformed. With continued reference to Figure 2, drive roller 30 is
mounted rotatably and in engagement with member 1. Motor 33 rotates r oller
15 30 to advance member 1 in the direction of arrow 27. Roller 30 is coupled to
motor 33 by suitable means such as a belt drive. Sheet-stripping roller 2g is
freely rotatable so as to readily permit member 1 to move in the direction of
arrow 27 with a minimum of friction.
Initially, a portion of imaging member 1 passes through charging
2~ station H. At charging station H, a eorona generating device, indicated
generally by the reference numeral 34, charges the photoconductive surface of
imaging member 1 to a relatively high, substantially uniform potential.
The charged portion of the photoconductive surface is then
advanced through exposure station I. An original document 35 is positioned
25 face down upon transparent platen 36. Lamps 37 flash light rays onto originaldocument 35, and the light rays reflected from original document 35 are
transmitted through lens 38 forming a light image thereof. Lens 3~ fc~cuses
the light image onto the charged portion of the photoconductive surface to
selectively dissipate the charge thereon. This records an electrostatic latent
30 image on the photoconductive surface which corresponds to the informational
areas contained within original document 35.
Thereafter, imaging member 1 advances the electrostatic latent
image recorded thereon to station J wherein it is contacted with positively
charged insulating toner particles 24', station J including a roller means 12,
35 coating 13, a charging injecting means 16, a toner supply reservoir 1~, pressur
bladel7, charging zone 19, and insulating toner particles 24. The details of the
~3~ 5
-ln
charging of the toner particles and deposition thereon on the imaging member
are illustrated with reference to Figure 1.
Imaging member 1 then advances the toner powder image to
transfer station K. At transEer station K, a sheet of support maierial 44 is
5 moved into contact with the ts~ner powder image. The sheet of support
material 44 is advanced to transfer station K by a sheet feeing apparatus (not
shown)O Preferably, the sheet feeding apparatus includes a feed roll contacting
the uppermost sheet of a stack of sheets. The feed roll rotates so as to
advance the uppermost sheet from the stack into a chute, which chute directs
10 the advancing sheet of support material into contact with the photoconductivesurface of member 1 in a timed sequence in order that the toner powder image
developed thereon contacts the advancing sheet of support material at
transfer station K.
Transfer station K incluc!es a corona generating device 46 which
15 sprays ions onto the backside of sheet 44, allowing for the attraction of the torler powder image from the photoconductive surface to sheet 44. After
transfer, sheet 44 moves in the direction of arrow 48 onto a conveyor (not
shown) which advances sheet 44 to fusing station L.
Fusing station L includes a fuser assembly, indicated generally by
20 the reference numeral S0, which permanently affixes the transferred toner
powder image to sheet 44. Preferably, fuser assembly 50 includes a heated
fuser roller 52 and a back-up roller 54. Sheet 44 passes between fuser`roller
52 and back-up roller 54 with the toner powder image contacting fuser roller
52. In this mannerl the toner powder image is permanently affixed to sheet
25 44~ After fusing, a chute guides the advancing sheet 44 to a catch tray for
subsequent removal from the printing machine.
Invariably, after the sheet of support material is separated from
the photoconductive surface of imaging member 1 some residual particles
remain adhering thereto. These residual particles are removed from the
30 photoconductive surface at cleaning station M. Cleaning station L includes a
rotatably mounted fibrous brush 56 in contact with the photoconducti-le
surface. The particles are cleaned from the photoconductive surface by the
rotation of brush 56 in contact therewith. Subsequent to cleaning, a discharge
lamp (not shown) floods photoconductive surface 12 with light to dissipate any
35 residual electrostatic charge remaining thereon prior to the charging thereof for the next successive imaging cycle.
'7g~
It is believed that the foregoing description is suff icient for
purposes of the present invention to illustrate the general operation of an
electrophotographic printing machine incorporating the features of the present
invention therein.
nlustrative examples of the imaging member 1 or 1~1 includes
inorganic and organic photoresponsive materials such as a~orphous selenium,
selenium alloys, including alloys of selenium-tellurium, selenium arsenic,
selenium antimony, selenium-tellurium-arsenic, cadmium sulfide, zinc oxide,
polyvinylcarbazole, layered organic photoreceptors, such as those containing as
an injecting contact, carbon dispersed in a polymer, overcoated with a
transport layer, which in turn is overcoated with a generating layer, and
finally an overcoating of an insulating organic resin, reference U.S. Patent
4,251,612, overcoated layers comprised of a substrate, a charge transport layer,and a charge generating layer, reference U.~. Patent 4,265,990 and the like.
Other organic photoreceptor materials include, ~dimethyl-
aminobenzylidene, ben2hydrazide; 2-benzylidene-amino-carbazole, 4-dimethyl-
amino-benzylidene, 2-benzylidene-amino-carbazole, (2-nitro-benzylidene)-p-
bromo-aniline; 2,4-diphenyl quinazoline; 1,2,~-triazine; 1,5-diphenyl-3-methyl
pyrazoline 2-(4'-dimethyl-amino phenyl)benzoxazole; 3-amino-carbazole; poly-
20 vinylcarbazole-trinitr~luorenone charge transfer complexes; phthalo-
cyanines, mixtures thereof, and the like. Generally, positively charged toner
compositions are employe~ when the photoreceptor is charged negatively as is
the situation withmost organic photoreceptors, while negatively charged toner
particles are employed when the photoreceptor is charged positively9 as is the
25 situation with most inorganic photoreceptors such as selenium.
Illustrative examples of insulating toner resin materials that can be
utilized include for example polyamides, epoxies, polyurethanes, vinyl resins
and polymeric esterification products of a dicarboxylic acid and adiol com-
prising a diphenol. Various suitable vinyl resins can be employed in the toners
30 o-f the present system including homopolymers or copolymers of two or more
vinyl monomers. Typical of such vinyl monomeric units include: styrene, ~
chlorostyrene vinyl naphthalene, ethylenically unsaturated mon~olefins such
as ethylene, propylene, butylene, isobutylene and the lilce; vinyl esters such as
vinyl chloride, vinyl bromide, vinyl fluoride, vinyl acetate, vinyl propionate,
35 vinyl benzoate, vinyl butyrate and the like; esters ot alphamethylene aliphatic
~3~'7~i~
-12-
monocarboxylic acids such asmethyl acrylate, ethyl arylate, n-butylacrylate,
isobutyl arylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylte,
phenyl acrylate, methylalphachloroacrylate, methyl metharylate, ethyl
met~arylate, butyl methacrylate and the like; acrylonitrile, methacrylonitrile,
5 acrylamide, vinyl ethers such as vinyl methyl ether, vinyl isobutyl ether, vinyl
ethyl ether, and the like; vinyl ketones such as vinyl methyl ketone, vinyl hexyl
ketone, methyl isopropenyl ketone and the like; vinylidene halides such as
vinylidene chloride, vinylidene chlorofluoride and the like; and N-vinyl indole,N-vinyl pyrrolidene and the like; and mixtures thereoI.
Generally toner resins containing a relatively high percentage of
styrene are preferred since greater image definition and density is usually
obtained with their use. The styrene resin employed rnay be a homopolymer of
styrene or styrene homologs of copolymers of styrene with other monomeric
groups containing a single methylene group attached to a carbon atom by a
double bond. Any of the above typic~l monomeric units may be copolymerized
with styrene by addition polymerization. Styrene resins may also be formed by
the polymerization of mixtures of two or more unsaturated monomeric
materials with a styrene monomer. The addition polymerization technique
employed emhraces known polymerization techniques such as free radical,
anionic and cationic polymerization processes. Any of these vinyl resins may
be blended with one or more resins if desired, preferably other vinyl resins
whicll insure good triboelectric properties and uniform resistance a~ainst
physical degradation. However, non-vinyl type thermoplastic resins may also
be employed including resin modified phenolformaldehyde resins, oilmodiIied
epo~y resins, polyurethane resins, cellulosic resins, polyether resins and
mixtures thereoE.
~Nso esterification products of a dicarboxylic acid and a diol
comprising a diphenol may be used as a preferred resin material for the toner
composition of the present invention. These materials are illustrated in U.S.
3,655,374, the disclosure of which is totally incorporated herein by reference,
the diphenol reactant being of the formula as shown in column 4, beginning at
line S of this patent and the dicarboxylic acid being of the formula as shown incolumn 6 of the above patent.
Optimum electrophotographic resins result from styrene butyl-
methacrylate copolymers, styrene vinyl toluene copolymers, styrene acrylate
copolymers, polyester resins, predominantly styrene or polystyrene based
6~
--13--
resins as generally described in U.S. Reissue 24,136 and polystyrene blends as
described in U.SO 29788,288.
The toncr resin particles can vary in diameter, but generally range
from about 5 microns to about 30 microns, and preferably from about 10
5 microns to about 20 microns. The toner resin is present in an amount so that
the total of all ingredients total about lOa percent, thus when 5 percent by
weight of an alkyl pyridinium compound is present and 10 percent by weight of
pigment such as carbon black is present, about 85 percent by weight of resin
material is used.
Various suitable pigments or dyes may be employed as the colorant
for the toner particles, such materials being well known, and including for
example, carbon black,nigrosine dye, aniline blue, calco oilMude, chrome
yellow, ultramarine blue, DuPont oil red, methylene blue chloride, phthalo-
cyanine blue and mixtures thereof. The pigment or dye should be present in
15 sufficient quantity to render it highly colored so that it will form a clearly
visibleimage on the recording member. For example, where conventional
xerographic copies ofdocuments are desired9 the toner may comprise a black
pigment such as carbon black or a black dye such flS amaplast black dye
available from the National Aniline Products Inc. Preferably the pigment is
20 employed in various amounts from about 3 pereent to about 20 percent by
weight based on the to$al weight of toner, however7 if the toner colorant
employed is a dye, substantially smaller ~uantities may be used.
Additionally, the toner resin may contain a magnetic material,
such as the magnetite Mapico Black, as a substitute for the colorant, or in
25 addition thereto, thereby resulting in a magnetic toner. Generally, the
magnetite is present in an amount of from about 40 percent by weight to about
80 percent by weight, and preferably from about 50 percent by weight to about
70 percent by weight.
In another feature of the present invention, the insulating toner
30 particles can contain charge enhancing additives, such as quaternary ammonim
compounds, alkyl pyridinium compounds, like cetyl pyridinium chloride9 and
the like. The charge enhancing additives, which are present in an amount of
from about 0.5 percent by weight to about 10 percent by weight, generally
impart a positive charge to the toner resin, and thus are primarily useful only
35 in those situations where the toner particles are being positively charged by the injecting electrode.
-14--
Other modifications of the present invention will occur to those
skilled in the art upon a reading of the present disclosure. These are intended
to be encompassed within the scope of the present invention. Thus also
envisioned within the scope of the present invention is a process and apparatus
5 for charging insulating toner particles comprised in operative relationship ofmeans for transporting insulating toner particles, and a means for injecting
charges into the insulating toner particles, the means for transporting, and themeans for injecting being charged to a predetermined potential. Subsequently
the charged toner particles can be deposited on a flexible or rigid imaging
10 member contained in an electrostatographic imaging device, as illustrated
herein.
