U.S. patent number 3,900,587 [Application Number 05/431,279] was granted by the patent office on 1975-08-19 for imaging process employing treated carrier particles.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to Myron James Lenhard, Joseph Mammino.
United States Patent |
3,900,587 |
Lenhard , et al. |
August 19, 1975 |
Imaging process employing treated carrier particles
Abstract
A carrier for electrostatographic developers comprising carrier
particles comprising metals, metal alloys, metal compounds and
mixtures thereof treated with a strongly adhering adsorbable
organic dye. This carrier is used with toner particles to develop
electrostatic latent images.
Inventors: |
Lenhard; Myron James (Penfield,
NY), Mammino; Joseph (Penfield, NY) |
Assignee: |
Xerox Corporation (Stamford,
CT)
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Family
ID: |
26912491 |
Appl.
No.: |
05/431,279 |
Filed: |
January 7, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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218014 |
Jan 14, 1972 |
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Current U.S.
Class: |
430/123.58;
430/111.34; 430/111.1 |
Current CPC
Class: |
G03G
9/1138 (20130101) |
Current International
Class: |
G03G
9/113 (20060101); G03g 013/08 () |
Field of
Search: |
;117/17.5,1B,1M,1S,27
;96/1R,1SD ;252/62.1 ;355/3,4,17 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Russian Patent Abstracts, Vol. 1, No. 1, Textiles Dying, No.
144460, Applying Colored Designs to Textiles by Kunova. .
Surface Chemistry by Osipow, Reinhold Publishing Co., (1962), pp.
540-555..
|
Primary Examiner: Sofocleous; Michael
Parent Case Text
This application is a divisional application of copending
application Ser. No. 218,014, filed Jan. 14, 1972.
Claims
What is claimed is:
1. An electrostatographic imaging process comprising the steps of
forming an electrostatic latent image on an imaging surface and
developing said electrostatic latent image by contacting said
electrostatic latent image with an electrostatographic developer
mixture comprising finely divided toner particles electrostatically
clinging to the surface of larger, dye-treated carrier particles,
said carrier particles comprising solid metallic particles selected
from the group consisting of metals, metal alloys, metal compounds,
and mixtures thereof coated with an adsorbed layer of an organic
dye wherein said dye-treated carrier particles are characterized as
being resistant to fluctuations in triboelectric properties,
whereby at least a portion of said finely divided toner particles
are attracted to and held on said imaging surface in conformance to
said electrostatic latent image.
2. An electrostatographic imaging process comprising the steps of
forming an electrostatic latent image on an imaging surface and
developing said electrostatic latent image by contacting said
electrostatic latent image with an electrostatographic developer
mixture comprising finely divided toner particles electrostatically
clinging to the surface of dye-treated carrier particles, said
dye-treated carrier particles comprising metallic carrier particles
coated with an adsorbed layer of an organic dye and wherein said
dye-treated carrier particles are characterized as being resistant
to fluctuations in triboelectric properties, said carrier particles
having an average particle diameter from between about 1 micron and
about 1,000 microns and having been selected from the group
consisting of metals, metal alloys, metal compounds, and mixtures
thereof, said dye having been selected in accordance with its
triboelectric properties with respect to said toner particles so
that when said toner particles are mixed or brought into contact
with said treated carrier particles either said treated carrier
particles or said toner particles are charged positively if said
toner particles are below said treated carrier particles in a
triboelectric series and negatively if said toner particles are
above said treated carrier particles in said triboelectric series,
whereby at least a portion of said finely divided toner particles
are attracted to and held on said imaging surface in conformance to
said electrostatic latent image.
3. An electrostatographic imaging process according to claim 2
wherein said metallic carrier particles are selected from aluminum,
cobalt, copper, iron, lead, magnesium, nickel, tin, zinc, gold,
silver, antimony, beryllium, bismuth, cadmium, calcium, manganese,
selenium, titanium, tungsten, vanadium, zirconium, metal oxides,
refractory nitrides, carbides, and mixtures thereof.
4. An electrostatographic imaging process according to claim 2
wherein said organic dye is selected from the group consisting of
azo dyes, azoic dyes, azine dyes ketone dyes, phthalocyanine dyes,
and mixtures thereof.
5. An electrostatographic imaging process according to claim 2
wherein said organic dye comprises Oil Red dye and said metallic
carrier particles comprise iron filings.
Description
BACKGROUND OF THE INVENTION
This invention relates in general to imaging systems and, more
particularly, to improved developing materials, their manufacture
and use.
The formation and development of images on the surface of
photoconductive materials by electrostatic means is well known. The
basic electrostatographic imaging process, as taught by C. F.
Carlson in U.S. Pat. No. 2,297,691, involves placing a uniform
electrostatic charge on a photoconductive insulating layer,
exposing the layer to a light and shadow image to dissipate the
charge on the areas of the layer exposed to the light and
developing the resulting electrostatic latent image by depositing
on the image a finely divided electroscopic material referred to in
the art as "toner." The toner will normally be attracted to those
areas of the layer which retain a charge, thereby forming a toner
image corresponding to the electrostatic latent image. This powder
image may then be transferred to a support surface such as paper.
The transferred image may subsequently be permanently affixed to
the support surface as by heat. Instead of latent image formation
by uniformly charging the photoconductive layer and then exposing
the layer to a light and shadow image, one may form the latent
image by directly charging the layer in image configuration. The
powder image may be fixed to the photoconductive layer if
elimination of the powder image transfer step is desired. Other
suitable fixing means such as solvent or overcoating treatment may
be substituted for the foregoing heat fixing step.
Many methods are known for applying the electroscopic particles to
the electrostatic latent image to be developed. One development
method, as disclosed by E. N. Wise in U.S. Pat. No. 2,618,552 is
known as "cascade" development. In this method, a developer
material comprising relatively large carrier particles having
finely divided toner particles electrostatically clinging to the
surface of the carrier particles is conveyed to and rolled or
cascaded across the electrostatic latent image bearing surface. The
composition of the toner particles is so chosen as to have a
triboelectric polarity opposite that of carrier particles. As the
mixture cascades or rolls across the image bearing surface, the
toner particles are electrostatically deposited and secured to the
charged portion of the latent image and are not deposited on the
uncharged or background portions of the image. Most of the toner
particles accidentally deposited in the background are removed by
the rolling carrier, due apparently, to the greater electrostatic
attraction between the toner and the carrier than between the toner
and the discharged background. The carrier particles and unused
toner particles are then recycled. This technique is extremely good
for the development of line copy images. The cascade development
process is the most widely used commercial xerographic development
technique. A general purpose office copying machine incorporating
this technique is described in U.S. Pat. No. 3,099,943.
Another technique for developing electrostatic images is the
"magnetic brush" process as disclosed, for example, in U.S. Pat.
No. 2,874,063. In this method, a developer material containing
toner and magnetic carrier particles is carried by a magnet. The
magnetic field of the magnet causes alignment of the magnetic
carriers in a brushlike configuration. This "magnetic brush" is
engaged with an electrostatic image bearing surface and the toner
particles are drawn from the brush to the electrostatic image by
electrostatic attraction.
While ordinarily capable of producing good quality images,
conventional developing materials suffer serious deficiencies in
certain areas. The developing materials must flow freely to
facilitate accurate metering and even distribution during the
development and developer recycling phases of the
electrostatographic process. Some developer material though
possessing desirable properties such as proper triboelectric
characteristics, are unsuitable because they tend to cake, bridge
and agglomerate during handling and storage. Adherence of carrier
particles to reusable electrostatographic imaging surfaces causes
the formation of undesirable scratches on the imaging surfaces
during image transfer and surface cleaning steps. The coatings of
most carrier particles deteriorate rapidly when employed in
continuous processes which require the recycling of carrier
particles by bucket or screw conveyors partially submerged in the
developer supply. Deterioration occurs when portions of or the
entire coating separates from the carrier core. The separation may
be in the form of chips, flakes or entire layers and is primarily
caused by fragile, poorly adhering coating materials which fail
upon impact and abrasive contact with machine parts and other
carrier particles. Carriers having coatings which tend to chip and
otherwise separate from the carrier core must be frequently
replaced thereby increasing expense and consuming time. Print
deletion and poor print quality occur when carriers having damaged
coatings are not replaced. Fines and grit formed from carrier
disintegration tend to drift and form unwanted deposits on critical
machine parts. Many carrier coatings having high compressive and
tensile strength either do not adhere well to the carrier core or
do not possess the desired triboelectric characteristics. The
triboelectric and flow characteristics of many carriers are
adversely affected when relative humidity is high. For example, the
triboelectric values of some carrier coatings fluctuate with
changes in relative humidity and are not desirable for employment
in electrostatographic systems, particularly in automatic machines
which require carriers having stable and predictable triboelectric
values. Thus, there is a continuing need for a better system for
developing electrostatic latent images.
SUMMARY OF THE INVENTION
It is, therefore, an object of this invention to provide developing
materials which overcome the above noted deficiencies.
It is another object of this invention to provide developing
materials which flow freely.
It is a further object of this invention to provide carrier coating
materials which tenaciously adhere to carrier cores.
It is still a further object of this invention to provide carrier
coatings which are resistant to chipping, flaking and the like.
It is another object of this invention to provide developers having
physical and chemical properties superior to those of known
developer materials.
The above objects and others are accomplished, generally speaking,
by providing dye treated metallic carrier particles having improved
properties. In general, the carrier treating materials of this
invention are organic dyes which are adsorbable on the outer
surface of metallic carrier particles. The adsorbed organic dye
adheres to the carrier surface through a mechanism which is not
clearly understood. The adsorbed organic dye may consist of
monolayers, multilayers, concentrations of dye material in tiny
capillaries of the adsorbent carrier surface or a combination of
these forms. The dye may be physically and/or chemically adsorbent
to the surface of the metal carriers.
Any suitable dye which is adsorbable on a metal surface may be
employed. Typical adsorbable dyes include: azo dyes such as Oil Red
(C.I. 258), Luxol Fast Blue AR, Solvent Blue 37 (C.I. 13390), Sudan
Red BV (C.I. 1125), and Sudan Orange RA New (C.I. 12055); azoic
dyes such as Napthol As-LT (C.I. 37540) and Fast Black LB Base
(C.I. 37205); acridine dyes such as Flaveosine (C.I. 46060) and
Acridine Orange R (C.I. 46055); azine dyes such as Safranine T
(C.I. 50240) and Rhoduline Violet (C.I. 50215); ketone amine dyes
such as Helindon Yellow (C.I. 5600) and Helindon Brown CR (C.I.
56045); methine dyes such as Astro Violet FF extra C.I. 48080) and
Astro Violet FN extra (C.I. 48075); nitro dyes such as Picric Acid
(C.I. 10305) and Brilliant Yellow (C.I. 10317); nitroso dyes such
as Dioxine L (C.I. 10015) and Gambine R (C.I. 10010); oxazine dyes
such as Ultracyanine (C.I. 51130) and Meta Celestine Blue (C.I.
51170); quinoline dyes such as Supra Light Yellow GGL (C.I. 47020)
and Quinoline Yellow (C.I. 47005); thiazine dyes such as
Indochromogen S (C.I. 52050) and Methylene Blue A (C.I. 52015);
thiazole dyes such as Primuline (C.I. 49000) and Thioflavin (C.I.
49005); triarylmethane dyes such as Wool Fast Violet FB (C.I.
44500) and Wool Fast Blue FGL (C.I. 44505); dioxazine dyes such as
Sirius Supra Blue FFB (C.I. 51305) and Sirius Light Blue FFGL (C.I.
51320); xanthene dyes such as Fanal Red 6BM (C.I. 45175) and Spirit
Fast Violet K (C.I. 45185); sulfur dyes such as Sulphur Brown 42
(C.I. 53030) and Sulphur Brown 35 (C.I. 53035); anthraquinone dyes
such as Alizarin Orange G (C.I. 58250) and dinitroanthrachrysone
disulfonic acid (C.I. 58510); indigoid dyes such as Soluble Vat
Blue 2B (C.I. 73066) and Indigo Yellow 3G (C.I. 73100);
phthalocyanine dyes such as Sirius Supra Green FFGL (C.I. 74320)
and Solvent Blue 24 (C.I. 74380), and mixtures thereof. Preferably,
the carrier particles are treated with a solution of the adsorbable
dye because greater control over uniform treatment of the carrier
particles is achieved. Satisfactory results are achieved with
solutions containing from about 0.5 to about 25 parts by weight of
dissolved adsorbable dye. Surprisingly, no free dye material is
observed with carrier particles treated with solutions containing a
dye concentration as high as 25 parts by weight dye. Generally, the
quantity of dye adsorbed on the carrier surfaces decreases per unit
time as the concentration of dissolved dye decreases. Various
additives may be added to the dye solution to promote adsorption of
the dye onto the carrier surface. For example, surface active
agents such as toluene, methyl ethyl ketone and methanol; surface
tension reducing agents such as ethoxylated nonyl phenols, for
example, Triton X-100, available from Rohm & Haas Company,
neutral detergents such as Sulframin DR, available from Ultra
Chemical Works, and dioxtyl sodium sulfosuccinate, for example,
Aerosol OT, available from American Cyanamid Company, as well as
core oxidation inhibitors such as amonium thiocyanate and cerric
sulfate may be employed in the dye solution. The rate of adsorption
of the dye is often improved by imparting vibratory energy to the
dye solution. Satisfactory results are achieved with vibratory
frequencies of from about 1700 to about 2,100 cycles per minute.
After the carrier particles are treated with the dye solution, the
solvent and excess dye may be removed by any suitable technique
such as by exposure to infrared heat lamps, oven drying, drying in
ambient air, forced air drying and the like. The amount of dye
adsorbed by a carrier depends upon numerous factors such as the
magnesium combination of materials employed, the length of contact
time, the temperature of the solution, the presence of additives
(e.g., surface active agents) the use of agitation, and other
conditions. The carrier need not be treated to the extent that
maximum dye adsorption is achieved. However, it is desirable to
remove all unadsorbed dye from the treated carrier mixture. Removal
of excess unadsorbed dye, if any, may be effected by any suitable
process such as by washing with a solvent, air separation, or
screening. Removal of unadsorbed dye is preferred to avoid
undesirable contamination of reusable photoreceptor surfaces and
variation in print quality as the unadsorbed dye material is
depleted from a reusable developer. Sufficient dye is adsorbed on
the carrier surface of this invention when a carrier core is merely
immersed in a solution of dye having a concentration of about 1/2
percent by weight, based on the weight of the solvent, at
70.degree. F. until completely wetted and thereafter removed and
dried. Complete wetting occurs when the observed color change of
the carrier surface stabilizes. Carrier surfaces comprising
aluminum, nickel, zinc, iron and alloys thereof treated with azoic,
azine, ketone, phthalocyanine dyes or mixtures thereof are
preferred because of the marked effect on the triboelectric value
of the carrier per given quantity of dye. Optimum results are
achieved with porous carrier surfaces treated with adsorbed dyes
because of the improved adherence and greater life of the adsorbed
dye.
Any suitable carrier particle containing a metal, metal compound,
metal alloy or mixture of metals which will adsorb organic dyes may
be employed. Typical metals include: aluminum, cobalt, copper,
iron, lead, magnesium, nickel, tin, zinc, gold, silver, antimony,
beryllium, bismuth, cadmium, calcium, manganese, selenium,
titanium, tungsten, vanadium, zirconium and mixtures and alloys
thereof. Many metallic compounds will also absorb dyes. Typical
metallic compounds include metal oxides such as aluminum oxide,
oxidized steel, nickel oxide, and zirconium oxide; refractory
oxides such as titanium oxide and magnesiud oxide; refractory
nitrides such as vanadium nitride and chromium nitride; carbides
such as tungsten carbide and silica carbide and the like. Typical
combinations of metal containing carrier and an adsorbable dye
include: aluminum or steel particles having an oxidized outer
surface treated with Alizarin Cyanin RR, Alizarin Green S,
Nigrosine 2 Y and Naphthalene Blue RS; iron particles and Oil Red
or Luxol Fast Blue MDSN; nickel and Dupont Oil Red or Luxol Fast
Blue Ar; zirconium and Luxol Fast Blue AR or Dupont Oil Red and the
like.
The carriers of this invention may be treated with an adsorbable
dye by any suitable means. Generally, the carriers are treated with
an adsorbable dye dissolved in a solvent. The carrier may be
treated with the dye solution by spraying, dipping, or any other
suitable technique. An ultimate treated carrier particle diameter
between about 1 and about 1,000 microns performs satisfactorily.
For a magnetic brush development process, the treated carrier
particles should have a diameter between about 1 to about 250
microns. In addition, carrier particles for use in magnetic brush
development systems should be attractable by a magnet. For cascade
development processes, the treated carrier particles should have a
diameter between about 30 microns and about 1,000 microns. Further,
carrier particles for cascade development should possess sufficient
density and inertia to avoid adherence to electrostatic images
during development. Adherence of carrier beads to a reusable
electrostatographic imaging surface is undesirable because of the
formation of deep scratches on the imaging surface during the image
transfer and drum cleaning steps, particularly when cleaning is
accomplished by a web cleaner such as the web disclosed by W. P.
Graff, Jr. et al. in U.S. Pat. No. 3,186,838.
The carrier particles may have a smooth, porous or rough surface
and may have a spherical, regular, or irregular configuration. For
cascade development processes, the carrier particles are preferably
selected to have a spherical shape for maximum control over copy
quality including control over image density, image definition, and
reduction of background deposits.
Any suitable pigmented or dyed electroscopic toner material may be
employed with the treated carriers of this invention. Typical toner
materials include: gum, copal, gum sandarac, rosin, cumaroneindene
resin, asphaltum, gilsonite, phenolformaldehyde resins, rosin
modified phenolformaldehyde resins, methacrylate resins,
polystyrene resins, polypropylene resins, epoxy resins,
polyethylene resins and mixtures thereof. The particular toner
material to be employed obviously depends upon the separation of
the toner from treated carrier beads in the triboelectric series.
Among the patents describing the electroscopic toner compositions
are U.S. Pat. Nos. 2,659,670 to Copley; 2,753,308 to Landrigan;
3,079,342 to Insalaco; Re 25,136 to Carlson; and 2,788,288 to
Rheinfrank et al. These toners generally have an average particle
diameter between about 1 and about 30 microns.
Any treated carrier particle may be employed in combination with
any suitable toner particle by selecting an adsorbable dye material
which will permit the carrier particles to acquire a charge having
an opposite polarity to that of the toner particles when brought in
close contact with the toner particles so that the toner particles
adhere to and surround the carrier particles. When a positive
reproduction of an electrostatic image is desired, the adsorbable
dye is selected so that the toner particles acquire a charge having
a polarity opposite to that of the electrostatic latent image.
Alternatively, if a reversal reproduction of the electrostatic
image is desired, the adsorbable organic dye is selected so that
the toner particles acquire a charge having the same polarity as
that of the electrostatic image. Thus, the adsorbable dye for the
carrier particles is selected in accordance with its triboelectric
properties in respect to the electroscopic toner so that when mixed
or brought into mutual contact, either the adsorbable dye component
or electroscopic toner component of the developer is charged
positively if the other component is below the first component in
the triboelectric series and negatively if the other component is
above the first component in the triboelectric series. By proper
selection of materials in accordance with their triboelectric
effects, the polarities of their charge when mixed are such that
the electroscopic toner particles adhere to and are coated on the
treated surfaces of carrier particles and also adhere to that
portion of the electrostatic image bearing surface having a greater
attraction for the toner than the carrier particles. Generally
speaking, satisfactory results are obtained when about 1 part by
weight of toner is used with about 10 to about 200 parts by weight
of treated carrier.
Surprisingly, the adsorbed dyes of this invention adhere extremely
well to carrier particle surfaces without the aid of a resin
binder. Thus, the problems encountered with resinous carrier
coatings such as carrier particle agglomeration during and
subsequent to coating, coating deterioration through chipping and
flaking, and print deletion due to loose carrier coating particles
are eliminated with the carriers of this invention. In addition,
carriers treated with adsorbed organic dyes possess greater
resistance to fluctuations in triboelectric properties for greater
periods of time.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following examples further define, describe and compare
exemplary methods of preparing the development system components of
the present invention and of utilizing them in a development
process. Parts and percentages are by weight unless otherwise
indicated. The examples, other than the control examples, are also
intended to illustrate the various preferred embodiments of the
present invention.
EXAMPLE I
About 1000 grams of iron filings having an average particle size of
about 100 microns is dispersed in a dye solution consisting of
about 1 gram of Oil Red dye (available from E. I. duPont de Nemours
& Company, Incorporated) dissolved in about 300 milliliters of
acetone. After the resulting slurry is stirred for about 5 minutes,
the excess dye solution is removed by decantation. The treated iron
filings are then loosely scattered in a shallow pan and dried in an
oven heated to about 140.degree.F. About 97 grams of the dried iron
particles are mixed with about 3 grams of toner particles
comprising a carbon black pigmented blend of polystyrene and
polybutylmethacrylate having a particle size of about 14 microns to
form a magnetic brush developer. The resulting magnetic developer
is then formed into a magnetic brush as described in U.S. Pat. No.
2,874,063 and employed to develop a positively charged
electrostatic latent image on a selenium photoreceptor surface. The
deposited toner image is electrostatically transferred to a paper
sheet. The transferred image is dense, very sharp and very little
background discoloration is observed.
EXAMPLE II
The process described in Example I is repeated with about 1 gram of
Luxol Fast Blue AR dye (available from E. I. duPont de Nemours
& Company, Incorporated) substituted for the Oil Red dye. The
toner particles deposit in the discharged areas of the positively
charged electrostatic latent image bearing selenium photoreceptor
surface to form a dense, sharp, reversal image.
EXAMPLE III
The process described in Example I is repeated with untreated iron
filings substituted for the treated iron filings. The resulting
toner image is characterized by extremely heavy background
discoloration caused by toner deposits in the charged as well as
discharged areas of the selenium photoreceptor surface. This
control example clearly illustrates that the same unsuitable
metallic carrier may easily be adapted to form either positive or
reversal toner images by employing the simple dye treatment of this
invention.
EXAMPLE IV
The developer described in Example III is formed into a magnetic
brush as described in U.S. Pat. No. 2,874,063 and employed to
develop a negatively charged electrostatic latent image bearing
zinc oxide binder plate surface. The toner particles deposit in the
charged areas to form clearly defined direct images devoid of
visible background toner deposits.
EXAMPLE V
The process described in Example IV is repeated with the developer
employed in Example I. The toner particles deposit in the
discharged areas to form dense reversal toner images.
EXAMPLE VI
The process described in Example IV is repeated with untreated iron
filings substituted for the dye treated iron filings. The resulting
toner image is characterized by poorly defined low density direct
and reversal images. Thus, the results described in Examples IV, V
and VI clearly demonstrate the rapid conversion of normally
unsuitable or marginal carrier material to excellent carriers by
treating the carrier materials with an adsorbable organic dye.
EXAMPLE VII
About 450 grams of zirconium oxide particles having an average
particle size of about 600 microns is dispersed in a dye solution
consisting of Safranine T dissolved in about 400 milliliters of
methyl ethyl ketone. After the resulting slurry is stirred for
about 5 minutes, the excess dye solution is removed by decantation
and the treated particles are dried. About 150 grams of the dried
treated carrier particles are mixed with about 1 gram of carbon
black pigmented styrenebutylmethacrylate copolymer toner particles
having a particle size of about 10-15 microns to form a developer
composition. The developer composition is employed in a Xerox Model
D electrostatic copying machine to develop a reversal charged
electrostatic latent image on a selenium photoreceptor surface. The
deposited toner image is sharp and clear with very little
background discoloration.
EXAMPLE VIII
About 450 grams of nickel particles having an average particle size
of about 450 microns is dispersed in a dye solution consisting of
Monastrol Green GNS dissolved in about 450 milliliters of toluene.
After the resulting slurry is stirred for about 5 minutes, the
excess dye solution is removed by decantation and the treated
particles are dried. About 100 grams of the dried treated carrier
particles are mixed with about 1 gram of carbon black pigmented
styrene-butyl methacrylate copolymer toner particles having a
particle size of about 16 microns to form a developer composition.
The developer composition is employed in a Xerox Model D
electrostatic copying machine to develop a positively charged
electrostatic latent image on a selenium photoreceptor surface. The
deposited toner image is dense, sharp and clear with no visible
discoloration due to background toner deposits.
EXAMPLE IX
About 450 grams of aluminum shot particles having an average
particle size of about 250 microns is dispersed in a dye solution
consisting of Monastrol Blue RFS dissolved in about 400 milliliters
of toluene. After the resulting slurry is stirred for about 5
minutes, the excess dye solution is removed by decantation and the
treated particles are dried. About 200 grams of the dried treated
carrier particles are mixed with about 1 gram of carbon black
pigmented styrenebutylmethacrylate copolymer toner particles having
a particle size of about 15 microns to form a developer
composition. The developer composition is employed in a Xerox Model
D electrostatic copying machine to develop a positively charged
electrostatic latent image on a selenium photoreceptor surface. The
deposited toner image is sharp, clear and dense with very little
discoloration due to background toner deposits.
EXAMPLE X
About 450 grams of aluminum-zinc shot particles having an average
particle size of about 250 microns is dispersed in a dye solution
consisting of Monastrol Blue BXS dissolved in about 450 milliliters
of toluene. After the resulting slurry is stirred for about 5
minutes, the excess dye solution is removed by decantation and the
treated particles are dried. About 150 grams of the dried treated
carrier particles are mixed with about 1 gram of toner particles
described in Example IX to form a developer composition. The
developer composition is employed in a flat plate type
electrostatic copying machine to develop a positively charged
electrostatic latent image on a selenium photoreceptor surface. The
deposited toner image is clear, sharp and dense with a very slight
coloration of background areas.
EXAMPLE XI
About 300 grams of iron shot particles having an average particle
size of about 100 microns is dispersed in a dye solution consisting
of Monastrol Blue GS dissolved in about 450 milliliters of toluene.
After the resulting slurry is stirred for about 5 minutes, the
excess dye solution is removed by decantation and the treated
particles are dried. About 100 grams of the dried treated carrier
particles are mixed with about 1 gram of toner particles described
in Example IX to form a developer composition. The developer
composition is employed in a flat plate type electrostatic copying
machine to develop a positively charged electrostatic latent image
on a selenium photoreceptor surface. The deposited toner image is
sharp, clear and dense with a slight coloration of the background
areas.
EXAMPLE XII
A control sample containing about one part colored toner particles
having an average particle size of about 10 to about 20 microns and
about 99 parts coated carrier particles available in the Xerox 813
Developer sold by the Xerox Corporation is cascaded across a
reusable electrostatic image bearing selenium surface. The
resulting developed toner image is electrostatically transferred to
a sheet of paper whereon it is fused by heat. After the copying
process is repeated 2,000 times, the developer mix is examined for
the presence of carrier coating chips and flakes. Numerous carrier
coating chips and flakes are found in the developer mix.
EXAMPLE XIII
The process of Example XII is repeated with the carrier described
in Example IX substituted for the Xerox 813 carrier. An examination
of the developer mix after test termination reveals substantially
no loose dye material abraded from the carrier surfaces.
EXAMPLE XIV
The process of Example XII is repeated with the carrier described
in Example X substituted for the Xerox 813 carrier. An examination
of the developer mix after test termination reveals substantially
no loose dye material abraded from the carrier surfaces.
EXAMPLE XV
The process of Example XII is repeated with the carrier described
in Example XI substituted for the Xerox 813 carrier. An examination
of the developer mix after test termination reveals substantially
no loose dye material abraded from the carrier surfaces.
EXAMPLE XVI
The process of Example XII is repeated with the carrier described
in Example VIII substituted for the Xerox 813 carrier. An
examination of the developer mix after test termination reveals
substantially no loose dye material abraded from the carrier
surfaces.
EXAMPLE XVII
The process of Example XII is repeated with the carrier described
in Example VII substituted for the Xerox 813 carrier. An
examination of the developer mix after test termination reveals
substantially no loose dye material abraded from the carrier
surfaces.
EXAMPLE XVIII
The process of Example XII is repeated with the carrier described
in Example II substituted for the Xerox 813 carrier. An examination
of the developer mix after test termination reveals substantially
no loose dye material from the carrier surfaces.
Although specific materials and conditions are set forth in the
above exemplary processes in making and using the treated carriers
of this invention, these are merely intended as illustrations of
the present invention. Various other toners, organic dyes,
carriers, additives, substitutes and processes such as those listed
above may be substituted for those in the Examples with similar
results.
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 included within the scope of this invention.
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