Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~74~66
BACKGROUND OF THE INVENTION
_
This invention relates to imaging ~ystems, and
more particularly, to improved xerographic developing
materials, thair manufacture, and use.
Electrostatography, that branch of the imaging
art which relates to the formation and utilization of
latent electrostatic charge patterns to record and
reproduce patterns in visible form is well known in the art.
When a photoconductor is employed to form these electrostatic
latent images by first charging and then selectively
exposing the photoconductive layer, this imaging method
is referred to as electrophotography and more commonly
known as xerography, the basic techniques of which are
disclosed in U. S. Patent 2,297,691. The latent electro-
static images thus formed may be developed or rendered
visible by deposition of a finely divided electroscopic
material referred to in the art as tonerO The image thus
obtained may be utilized in a number of ways t for example,
the image may be fused or fixed in place or transferred
and then fixed to a second surface.
Electrography, the other broad general branch
of electrostatography, generally divided into two broad
sectors which are referred to as xeroprinting and electro-
graphic or TESI recording, does not employ a photoresponsive
medium, the c:harging and selective discharging thereof to
form its latent electxostatic image. Xeroprinting, the
electrostatis~ analog of ordinary printing is more fully
described in U. S. Patent 2,576,047 to Schaffert. TESI
imaging or transfer of electxostatic images, more fully
described in U. S. Patent 2,285,814, involves the formation
~ ,.
--2--
,
~7~66
o an electrostatic charge pattern conforming to a desired
reproduction on a uniform insulating lay~r by means of an
electrical dischaxge between two or more electrodes on
opposite sides of the insulating medium. The lines of force
generated by the latent electrostatic image are employed to
control the deposition of the toner material to form an image.
Various developers both powder and liquid and developing
systems are well known to those skilled in the art including
cascade development as disclosed in U. S. Patent 2,618,552 to
E. N. Wise; magnetic brush development as generally described
in U. S. Patent 2,874,063; powder cloud development as generally
described in U. S. Patent 2,784,109; touchdown development
descri~ed in U. S. Patent 3,166,432; and liquid development
as described in U. S. Patent 2,877,133 among others. These
development systems, though they enjoy widespread use for
black and white reproductions may also be employed in
other colors and combinations of colors for example, a
trichromatic color system of either the additive or
subtractive color formation types. In full color systems
at least three different colors must be employed to synthesize
any other desired color which involves generally the formation
of at least ~hree color separation images and their combination
in registration with each other to form a color reproduction
of the original. Thus, in any o the electrostatographic
recoxding systems at least three diferent latent electro-
static images must be foxmed, developed with different color
toners and combined to orm the final image. For example,
in color xerography an electrostatic latent image resulting
from exposure to a first primary color may be formed on the
~7~6
photoconductive layer and developed with a toner complementary
to the primary color. In a s:imilar fashion, succeeding
developments of electrostatic latent images corre~ponding
to primary colors are accomplished with complementary toners.
When exposing through color separation negatives, the toner
is the complament of the radiation of exposure.
In a three color electrophotographic system which
amploys superimposed color images it is necessary that the
toners be quite transparent except for the underlying one
so as not to ob~cure the different colored toner images
below it and that each toner have sufficient color saturation
at the same time and brightness to satisfy the colorimetric
requirements for three color synthesis of natural color
images. As can be àppreciated, these requirements are
virtually diametrically opposed and are further complicated
by the additional requirement that when all the toners are
com~ined, they must produce a deep black. It has been found
that in order to produce deep blacks in a color system it is
required to superpose four different colored images including
a black registered image. Additional problems generally
arise when inorganic pigments are used as the coloring
material either in printing inks or electrophotographic
toners since it is difficult to achieve proper color balance
and saturation while at the same time keeping the colors
transparent. When employing inorganic pigments, the range
of colors available is relatively narrow and these pigments
are found to impart opacity to the materials to which they
are added even in relatively small amounts.
Bartoszawicz et al in U. S. Patent 3,345,293
teaches colored electrophotographic toners comprising
-4-
.. .. . . , . . , : .. .
~74~66
substantially transparent resin particles containing organic
dye pigments. These materials are stated to be advantageous
in their use over prior art materials in that they are more
resistant to bleeding of color upon toner fusing and they
are specifically adaptable for use in three color electro-
photographic processes since their colors are yellow, cyan,
magenta and their mixtures in pairs produce blue, red and
green while the three toners together produce a black.
Notwithstanding the apparent advantages of the Bartoszewicz
et al toners, there are nevertheless disadvantages connected
with these specific toners, specifically in the case of the
yellow toner when employed in an automatic electrophoto-
graphic machine. The yellow colorant as ad~anced by
Bartoszewicz et al consists essentiall~ of from about .92
to about 1.08 parts by weight of 3,3'-dichloro, 4'-bis
(2"-acetyl-2l'-azo-o-acetotoluidide)biphenyl per 10 parts by
weight of a substantially transparent resin. The problem in
employing this colorant residas in its inability to disperse
substantially uniformly in transparent resin materials and
more significantly the undersirable triboelectric properties
which result from its use causing poor images of low contrast
and low machine life. It is found that the triboelectric
properties of the resulting toner material are not maintained
under conditions where the toner is exposed to mechanical
abrasion, high temperatures, and high ambient humidity conditions,
all of which are common in electrophotographic machines~ This
results in a number of problems includin~ poor transfers from
the drum surface to the cop~ sheet as well as maintaining
~37~ 6
cleanliness of the drum. More specifically, it is Eound that
in electrophotographic machine use this toner imp~cts on its
carrier further degrading the already existing undesirable
triboelectric relationship and thereby adversely effecting
machine performance.
SUMMARY OF THE INVENTION
In accordance with one aspect of this invention there
is provided an electrostatographic material for developing
electrostatic latent images comprising a resin material and
a colorant, said colorant sa~isfying the formula:
o7 C~3 CH3 ~
C~ll C6Hll
.. . :
In accordance with anothèr aspect of-this invention
there is provided an electrostatographic imaging process
comprising establishing an electrostatic latent image on a
surface and contacting said surface with an electrostatographic
material-comprising a resin material and a colorant, the
colorant having the formula indicated above.
In accordance with another aspect of this invention
there is provided a color electrophotographic imaging process
comprising charging a photoconductive member, exposing said
photoconductive member to an original to be reproduced through
a filter of one color thereby selectively discharging said
photoconductive member, developing the electros*atic image
formed thereby with a developer of a complementary color, said
developer being one member of the group consisting of copper
tetra-4-(octadecylsulfonamido) phthalocyanine pigment, cyan
toner and a methyl terpolymer coated steel carrier; 2,9-dimethyl-
. . ~'
- 6 - ~
. . . ~ .
~74~66
quinacridone identi~ied in the Colour Index as C.I. Pigment
Red 122, magenta toner and a nickel berry carrier; azo dye C.I.
21230 Solvent Yellow 29 yellow toner and a methyl terpolymer
coated steel carrier; charging said photoconductor for a
second time and selectively exposing said photoconductor to
the same image through a filter of another primary color,
developing the latent electrostatic image formed thereby with
a developer of a complementary color, said developer being
another member selected from the group consisting of copper
tetra-4-~octadecylsulfonamido) phthalocyanine pigment, cyan
toner and a methyl terpolymer coated steel carrier; 2,9-dimethyl-
quinacridone identified in the Colour Index as Pigment Red 122,
magenta toner and a nickel berry carrier; and azo dye C.I.
21230 Solvent Yellow 29 yellow toner and a methyl terpolymer
coated steel carrier; charging said photoconductive member for
a third time, exposing said photoconductor to the same imAge
through a filter of the remaining primary color and developing
the latent electrostatic image with a complementary developer,
said developer being the remaining developer of the group con-
sisting of copper tetra-4-(octadecylsulfonamido) phthalocyanine
pigment, cyan toner and a methyl terpolymer coated steel
carrier; 2,9-dimethylquinacridone identified in the Colour
Index as Pigment Red 122, magenta toner and a nickel berry
carrier; and azo dye C.I. 2I230 Solvent Yellow 29 yellow toner
and a methyl te:rpolymer coated steel carrier.
The colorant having the formula previously noted,
classified in the Colour Index as C.I. Solvent Yellow 29, C.I.
21230, is combined with an appropriate electrophotographic
resin, for example, a styrene-n-butyl-methacrylate resin to
form a toner and then combined with a conventional carrier
for example, methyl terpolymer coated steel carrier to provide
a highly desirable yellow developer ~or use in color electro-
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. . ~ ~. . - . .
~079~ 6
photography. These are hereinafter referred to as Solvent
Yellow 29 developers and Yellow 29 toners and are distinctly
different and superior to those yellow colorants taught by
Bartoszewicz et al and other conventional yellow developers
since they are ~ound to be transparent while other known
colorants are opaque. These developers unlike other yellow
developers are readily dispersible and have desirable
solubility properties in electrostatographic resins. The
most significant property of these developers, however, is
their superior triboelectric properties or tribo which allow
these developers to be employed very successfully in
electrophotographic developing applications. When employed
in an automatic electrophotographic imaging device where
developer is employed, it is found that the machine tends to
impact the toner and the carrier for both prior art yellow
colorants and Solvent Yellow 29 ~olorants; however, where as
in the case of prior art yellow colorants the triboelectric
property tends to degrade
~74166
and consequently machine performance is severel~ curtailed,
Solvent Yellow 29 developers maintain their triboelectric
properties and in some cases have been found to improve
upon continued impaction, thus providing superior machine
life and performance.
It has been found that upon continuous use in
a conventional àutomatic electrophotographic imaging device,
for example, a Xerox 720 Copier under controlled conditions
that a benzidine yellow toner as taught by Bartoszewicz et al
displayed a machine life of 1400 prints, two conventionally
employed black toners have useful lives of 4200 and 9000
prints whereas a Solvent Yellow 29 toner composition exhibited
a useful life in excess of 25,000 prints with no apparent
adverse effects. It is, therefore, demonstrated that prior
art colorants including the yellow colorant of Bartoszewicz
et al when combined with suitable resins to optimize their
respective performances and employed in the same machine
under identical conditions do not in any way begin to compare
with the useful life and performance of the toner compositions
of the instant invention. Further upon extended use in machine
testing, conventional black toners tend to drop tribo-
electrically in steps until they reach a final failure level
after which imaging is difficult if not impossible. These
steps are not evident in prior art yellow toner life studies
such as the Bartoszewicz et al yellow toner, since these
toners exhibit a steady and extreme drop in tribo, resulting
in shortened m,achine life and poor machine performance.
Yellow 29 toner compositions, much the same as diarylide
yellow compositions, exhibit very stable tribo values within
a well defined range with acceptable copy quality and
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operational characteristics over a test run o~ over 25,000
prints. In addition, the impac:tion rating exhibited by this
yellow toner and a developer is actually less than generated
by conventionally employed blac:k developers over an equilvalent
test period. From the table below, Table I, developer
compositions employing Solvent Yellow 29 colorants, it can
be seen that developer compositions employing Solvent Yellow 29
colorants are capable of achieving at least 25,000 print cycles
o~ acceptable copy quality and development characteristics.
Impaction was not found to be a problem so that this parameter
ic not at all reported. In addition, it may seem
that Solvent Yellow 29 pigment itself when employed as reci~ed
above exhibits high triboelectric characteristics far superior
-to tho~e found in the prior art as may be seen by the following
table.
TABLE I
TONER OF EXAMPLE I Carrier-Methylterpolymer coated
steel beads, 100 ~ particle size
Toner
Conc. Tribo Tribo Background
Prints (%)(Uc/qm) Product Densit~ Avera~e _
2~% RHInitial 2.43 12.42 30.181.16 .010
500 3.09 12.22 37.76 .92 .01~
l.OK 3.09 12.65 39.72 .87 .010
1.5R 3.07 12.50 38.38 .94 .010
2.OK 2.78 13.42 37.31 .93 .010
2.5R 2.81 13.11 36.83 .97 .010
3.OK 2.'71 14.48 39.25 .94 .010
3.5K 2.49 14.64 36.45 .89 .010
4.OK 2.';1 14~06 35.66 .81 .010
4.5K 2.04 15.81 32.26 .84 .010
5.OK 2.;26 15.12 34.17 .84 .010
5.5K 2.:37 14.57 34.53 .89 .010
6.OK 2.59 13.29 34.42 .92 .010
--10--
~9~74~66
TABLE I (Continued)
Toner
Conc.Tribo Tribo Background
Prints (%)(~c/qm) Product Density Average
6.5K 2.4013.98 33.55 .82 .010
7.OK 2.5312.50 31.63 1.06 .010
7.5K 2.3213.16 30.53 1.02 .010
8.5K 2.3514.66 34.46 1.04 .010
9.5R 2-.8714.83 42.56 .88 .010
lO.OK 2.2614.90 33.67 .98 .010
ll.OK 2.2513.99 31.49 .92 .010
12.OK 2.0311.54 23.42 .85 .010
13.OK 2.0612.42 25.59 .93 .010
13.5K 1.9511.00 21.45 .85 .010
14.OK 2.2411.14 24.96 1.34 .010
15.OK 2.2112.94 27.94 1.01 .010
16.OK 2.0512.33 2~.28 .92 .010
16.5K 1.9711.89 23.28 .84 .010
17.OK 2.2412.50 28.00 1.11 .010
- 18.OK 2.0914.75 30.83 .66 .010
l9.OK 2.0615.14 31.18 .72 .010
8~/o RH
19.5~ 2.2410.42 23.35 .98 .010
20.0K 2.178.71 18.90 1.05 .010
2a.5K 2.2710.42 23.35 .98 .010
21~ OK 1.59lD.93 17.38 .86 .010
21.5K 2.117.89 16.66 1.04 .010
22.OK 2.028.40 16.97 1.04 .010
22.5K 2 .139. 36 19.93 .94` .010
23. OK 1. 828.45 15.36 .82 - .010
24.OK 1.549.58 14.76 .54 .010
25.OK 1.6110.26 16.51 .94 .010
26.OK 1.727.91 13.61 .92 .010
Structurally the Solvent Yellow 29 yellow colorants
satisfying the following formula: --
OH CH CH3 OH
C6Hll C6Hll
.
differ from the diarylide yellow colorants listed in the Colour ::
Index as C. I. 21090 Pigment Yellow 12 and disclosed in
Canadian Patent No. 986~767~ issued April 6~ 1976~ Warren E.
Solodar, satisfying the formula:
-11-
~741~6
IH3 l H3
COH Cl Cl HOC
~MEI-OC~C--N=~N=~--C-CO ~
and from the benzidine yellow colorants as disclosed by
Bartoszewicz et al listed in the Colour Index as C.I. 21095
Pigment Yellow 14 and satisfying the following formula:
c~3 CH3
CH3 1 0H C1 C1 C_OH H3C
~lHOC- ~ _ I_CO~I~
Any suitable resin material may be used for the
toner compositions of the present invention. As previously
stated, substantially transparent resins are preferred when
the toner is to be used in a three color electrophotographic
system. Although any substantially transparent resin
material may be utilized as the resin component of this toner,
it is preferable that resins having other desirable properties
be utilized in this invention. Thus, for example, it is
desirable that a resin be used which is a non-tacky solid
at room temperature so as to facilitate handling and use
in the most common electrophotographic processes. Thermal
plastics are Idesirable with melting points significantly
above room temperature, but below that of which ordinary
paper tends to char so that once the toner images form
-12-
~ ~ 7 ~ ~ 6
thereon or transfer to a paper copy sheet it may be employed
and fixed to paper copy sheets by other techniques, such as,
subjecting the paper copy sheet bearing the powder image to
vapors of a solvent for the resin as generally described in
U. S. Patent 2,776,907. The resins selected should desirably
have good triboelectric properties and have sufficient
insulating properties to hold charge so that they may be
employed in a number of development systems.
While any suitable transparent resin possessing
the properties as above described may be employed in the
system of the present invention, particularly good results
are obtained with the use o~ vinyl resins and polymeric
esterification products of a dicarboxylic acid and a diol
comprising a diphenol. Any suitable vinyl resin may be
employed in the toners of the present system including homo-
polymers or copolymers of two or more vinyl monomers.
Typical such vinyl monomeric units include: styrene;
p-chlorostyrene; vinyl naphthalene; ethylenically unsaturated
mono-olefins such as ethylene, propylene, butyIene, isobutylene
and the like; vinyl esters such as vinyl chloride, vinyl
bromide, ~inyl fluoride, vinyl acetate, vinyl propionate,
vinyl benzoate, vinyl butyrate and the like; esters of
alphamethylane aliphatic monocarboxylic acids such as
methyl acrylate, ethyl acrylate, n-butylacrylate, isobutyl
acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl
acrylate, phenyl acrylate, methyl-alpha~chloroacrylate,
methyl methacrylate, ethyl methacrylate, butyl methacrylate
and the like; acrylonitrile, methacrylonitrile, acrylamide,
vinyl ethers such as vinyl methyl ether, vinyl isobutyl
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74~6
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 compounds such as N-vinyl pyrrole, N-vinyl carbazole,
N-vinyl indole, N-vinyl pyrrolidene and the like; and
mixtures thereof.
It is generally found that toner resins containing
a relatively high percentage of styrene are preferred since
greater image definition and density is obtained with their
use. The styrene resin employed may be a homopolymer of
styrene or styrene homologs or 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 typical 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 embraces
known polymerization techniques such as free radical,
anionic and cationic polymerization processes. Any of
these vinyl resins may he blended with one or more other
resins if desired, preferably other vinyl resins which
insure good t:riboelectric stability and uniform resistance
against physi.cal degradation. However, non-vinyl type
thermoplastic: resins may also be employed including rosin
modified phenol formaldehyde resins, oil modified epoxy
resins, polyurethane resins, cellulosic resins, polyether
resins and mixtures thereof.
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~IL074~6
Polymeric esterification products of a dicarboxylic
acid and a diol comprising a diphenol may also be used as a
preferred resin material for the toner compositions of the
instant invention. The diphenol reactant has the general ormula:
X X'
H(OR')n10 ~ R ~ O(OR")n2H
wharein R represents substituted and unsubstituted alkylene
radicals having from 2 to 12 carbon atoms, alkylidene radicals
having from 1 to 12 carbon atoms and cycloalkylidene radicals
having from 3 to 12 carbon atoms; R' and R" represent substi-
tuted and unsubstituted alkylene radicals having from 2 to
12 carbon atoms, alkylene arylene radicals having from 8 to
12 carbon atoms, and arylene radicals; X and X' represent
hydrogen or an alkyl radical having from 1 to 4 carbon atoms;
and nl and n2 are each at least 1 and the average sum of n
and n2 is less than 21. Diphenols wherein R represents an
alkylidene radical having from 2 to 4 carbon atoms are
preferred because greater blocking resistance; increased
definition of xerographic characters and more complete
transfer of toner images are achieved. Optimum results are
obtained with diols in which R' is an isopropylidene radical
and R' and R'l are selected from the group consisting of propylene
and butylene radicals because tha resins formed from these diols
possess higher agglomeration resistance and penetrate extremely
rapidly into paper receiving sheets under fusing conditions.
Dicarboxylic acids having from 3 to 5 carbon atoms are
-15-
~L~74~66
preferred because the resulting toner resin possesses
greater resistance to film formation on reusable imaging
surfaces and resist the formation of fines under machine
operation conditions~ Optimum results are obtained with
alpha unsaturated dicarboxylic acids including fumaric
acid, maleic acid or maleic acid anhydride because maximum
resistance to physical degradation of the tonar as well as
rapid melting properties are achieved. Any suitable-
diphenol which satisfies the above formula may be employed.
Typical such dipenols include: 2,2-bis(4-beta hydroxyl
ethoxy phenyl)-propane, 2,2-bis(4-hydroxy isopropoxy
phenyl) propane, 2,2-bis(4-beta hydroxy ethoxy phenyl)
pentane, 2,2-bis(4-beta hydroxy ethoxy phenyl)-butane,
2,2-bis(4-hydroxy-propoxy-phenyl)-propane, 2,2-bis(4-hydroxy
-propoxy-phenyl) propane, 1,1-bis(4-hydroxyl-ethoxy-phenyl)
-butane, 1,1-bis(4-hydroxyl isopropoxy-phenyl) heptane,
2,2-bis~3-methyl-4-beta-hydroxy ethoxy-phenyl) propane,
1,1-bis(4-beta hydroxy ethoxy phenyl)-cyclohexane, 2,2'-bis
~4-beta hydroxy ethoxy phenyl)-norbornane, 2,2'-bis(4-beta
hydroxy ethoxy phenyl) norbornane, 2,2-bis(4-beta hydroxy
styryl oxyphenyl) propane, the polyoxyethylene ether of
isopropylidene diphenol in which both phenolic hydroxyl
groups are oxyethylated and the average number of oxy~thylene
groups per mole is 2.6, the polyoxypropylene ether of
2-butylidene cliphenol in which both the phenolic hydroxy
groups are oxyalkylated and the average number of oxypropylene
groups per mo]e is 2.5, and the like. Diphenols wherein
R represents zm alkylidene radical having from 2 to 4
carbon atoms and R' and R" represent an alkylene radical
-16-
~ 7~6~
having from 3 to 4 carbon atoms are preferred because
greater blocking resistance, increased deinition of
xerographic characters and more complete transfer of toner
images are achieved. Optimum xesults are obtained with
diols in which R is isopropylidene and R' and R" are
selected from the group consisting of propylene and butylene
because the resins formed from these diols possess higher
agglomeration resistance and penetrate extremely rapidly
into paper receiving sheets under fusing conditions.
Any suitable dicarboxylic acid may be reacted
wi~h a diol as described above to form the toner compositions
of this invention either substituted or unsubstituted,
saturated or unsaturated~ having the general formula:
HOOC R~n COOH
wherein R''`' represents a substituted or unsubstituted alkylene
radical having from 1 to 12 carbon atoms, arylene radicals
or alkylene arylene radicals having from 10 to 12 carbon
atoms and n3 is lass than 2. Typical such dicarboxylic
acids including their existing anhydrides are: oxalic acid,
malonic acid, succinic acid, glutaric acid~ adipic acid,
pimelic acid, suberic acid, azelaic acid, sebacic acid,
phthalic acid, mesaconic acid, homophthalic acid, isophthalic
acid, terephthalic acid, o-phenyleneacetic-beta-propionic
acid, itaconic acid, maleic acid, maleic acid anhydride,
fumaric acid, phthalic acid anhydride, traumatic acid,
citraconic acid, and the like. Dicarboxylic acids having
from 3 to 5 carbon atoms are preferred because the resulting
toner resins possess greater resistance to film formation
-17-
~74~ 6
on reusable imaging surfaces and resist the formation o~
fines under machine operation conditions. Optimum results
are obtained wit~ alpha unsaturated dicarboxylic acids
including fumaric acid, maleic acid, or maleic acid anhydride
because maximum resistance to physical degradation of the
toner as well as rapid melting propexties are achieved. The
polymerization esterification ]products may themselves be
copolymerized or blended with one or more other thermoplastic
resins, preferably aromatic resins, aliphatic resins, or
mixtures thereof. Typical thermoplastic resins include
rosin modified phenol formaldehyde resins, oil modified
epoxy resins, polycarbonate, polysulfone, polyphenylene
oxide, polyurethane resins, cellulosic resins, vinyl
type resins and mixtures thereof. When the resin component
of the toner contains an added resin, the added component
should be present in an amount less than about 50 percent
by weight ba3ed on the total weight of the resin present
in the toner. A relatively high percentage of the polymeric
diol and dicarboxylic acid condensation product in the
resinous component of the toner is preferred because a
greater reduction o fusing temperatures is achieved with a
given quantity of additive material. Further, sharper images
and denser images ar~ obtained when a high percentage of
the polymeric diol and dicarboxylic acid condensation product
is present in the toner. Any suitable blending technique
such as hot melt, solvent, and emulsion techniques may be
employed to incorporate the added resin into the toner
mixture. The resulting resin blend is substantially
homogeneous and highly compatible with pigments and dyes~
Where suitable, the colorant may be added prior to,
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~7~66
simultaneously with or subsequent to the blending or
polymerization step.
Preferred electrophotographic results with the
Solvent Yellow 29 colorant of the instant invention are achieved
with styrene-butyl methacrylate copolymers, styrene-vinyl-
toluene copolymers, styrene-ac:rylate copolymers, polystyrane
resins, predominantly sty.rene or polystyrene based resins
as generally described in U. S. Reissue Patent 25,136 to
Carlson, and polys~yrene blends as described in U. S. Patent
2,788,288 to Rheinfrank and Jones~ Optimum results are
achieved with the Yellow 29 of the instant invention and
styrene-n-butylmethacrylate copolymer resins to form a toner
of long life and low impaction.
Any well known toner mixing and comminution
technique may be employed to provide the toner compositions
of the instant invention. For example, the ingredients
may be thoroughly mixed by blending, ex rusion and milling
and thereaft~r micropulverized. In addition, spray drying
a suspension of tha ingreaients, a hot melt or a solution of
the toner composition may also be employed.
The toners of the invention may be any size which
will result in a satisfactorily developed image, Toners of
the invention suitable for use with a carrier in cascade
or magnetic aevelopment generally have an average particle
size of about 5 microns to about 45 microns. A preferred
average particle size range is about 10 microns to about
19 microns to result in a print of maximum density.
Where carrier materials are employed in connection
with the toner compositions of the instant invention in
cascade and magnatic brush development, the carrier particles
employed may be electrically conductive, insulating, magnetic
--19--
.. . . . .. .
~ ~74~66
or non-magnetic, as long as the carrier particles are capable
of triboelectrically obtaining a charge of opposite polarity
to that of the toner particles so that the toner particles
adhere to and surround the carrier particles. In developing
a positive reproduction of an lelectrostatic imaga, the carrier
particle is selected so that the toner particles acquire a
charge having a polarity opposite to that of the electrostatic
latent image so that toner deposition occurs in image areas.
Alternatively, in reversal reproduction of an electrostatic
latent image, the carriers are selected so that the toner
particles ac~uire a charge having the same polarity as that
of the electrostatic latent image resulting in toner deposition
in the non-image are~s. Typical carrier materials include:
sodium chloride, ammonium chloride, aluminum potassium
chloride, Rochelle salt, sodium nitrate, aluminum nitrate,
potassium chlorate, granular zircon, granular silicon, methyl
methacrylate, glass, steel, nickel, iron, ferrites, ferro-
magnetic materials, silicon dioxide and the like. The
carriers may be employed with or without a coating. Many of
the foregoing and typical carriers are described by
L. E. Walkup in U. S. Patent 2l618,551; L. ~. Walkup
et al in U. S. Patent 2 r 638,416; E. N. Wise in U. S. Patent
2,618,552; R. H. Hagenbach et al in U. S. Patent 3,591,503
and 3,533,835 directed to electrically conductive carrier
coatings, and B. J. Jacknow et al in U. S. Patent 3,526,533
directed to polymer coated carriers and nodular carriers
having pe~bled surface as disclosed in Serial No. 357,988,
filed May 7, 1973, now U. SO Patent 3,847,604, a divisional
of Serial No. 151,995, filed June 10, 1971, now U. S. Patent
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~L~74~6~
3,767,568. An ultimate coated carrier particle diameter
between about 50 microns to about 1,000 microns is suitable
because the carrier particles 1:hen possess sufficient density
and inertia to avoid adherence to the electrostatic images
during the cascade development process. A preferred particle
size is between about 75 and 4()0 microns. Optimum performance
with the toner of the instant invention is about 100 microns
for best density images and long life. The carrier may be
employed with the toner composition in any suitable combination,
generally satisfactory results have been obtained when about 1
part toner is used with about 10 to about 200 parts by weight
of carrier.
Preferrad carriers or use with toner compositions of
the instant invention are th-ose of nickel berry and terpol~ner
coated steal. Nickel berry carriers are a mem~er of a group of
nodular carrier beads disclosed in U. S. Patents 3,847,604
and 3,767,568, characterized by a pebbled sur~ace with
recurring recesses and protrusions giving the particles a
relati~ely large external surface area and composed of nickel.
Such nodular carrier beads have high surface-to-mass ratio
as compared with substantially smooth-surfaced carriar beads
o~ the same mass. Using the nodular carrier materials, one
can obtain the benefits o both large and small carrier beads
while avoiding their shortcomings. Nodular carrier particles
present a plurality of small spherical surfaces with recesses
defining pochets for toner particles.
The nodular carrier beads are three dimensional
solids approximately 50 to 1,000 microns in size of roughly
berry, cuboid,al, rounded, irregular or spheroidal shape, and
with surface irregularities formed by numerous nodules and
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.
1~7~:~L66
recesses. Though the beads may have randomly spaced voids or
a slight d~gree of porosi~y, they should have predominantly
solid cores. Preferred carrier beads have generally rounded
nodules and are generally sphe:roidal in shape thus giving an
appearance reminiscent of a raspberry or cluster of grapes.
Terpolymer carriers '~re disclosed in U. S. Patent
3,526,533. The terpolymer carriers comprise a core
coated with a composition which is formed from the addition
polymerization reaction between monomers or prepolymers of
styrene, methylmethacrylate and unsaturated organo silanes,
silanols or siloxanes having from 1 to 3 hydrolyzable groups
and an organic group attached directly to the silicon atom
containing an unsaturated carbon to carbon linkage capable of
addition polymerization. Optimum with the toner of the instant
invention is~a steel carrier core coated with the composition
of Example XIII of U. S. Patent 3,526,533 to form a methyl
terpolymar carrier which provides a developer composition
which results in good density coverage and long life~
The electrostatic latent images developed by the
toner compositions of the instant invention may reside on
any surface capable of retaining charge. In electrophoto-
graphic applications a photoconducti~e m mber is employed
to form the electrostatic lat~nt Lmage. The photoconductive
layer may comprise an inorganic or an organic photoconductive
matPrial. Typical inorganic materials include: sulur,
selenium, zinc sulfide, zinc oxidet zinc cadmium sulide,
zinc magnesium oxide, cadmium selenide, zinc silicate,
calcium strontium sulfide, cadmium ~ulfide, mercuric iodide,
mercuric oxide, mercuric sulfide, indium trisulfide, gallium
selenide, arsenic disulfide, arsenic trisulfide, arsenic
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,: . .
~7~166
triselenide, antomony trisulfide, cadmium sulfoselenide and
mixtures thereof. Typical organic photoconductors include:
triphenylamine; 2,4-bis(4,4'-diethylamino-phenol)-1,3,4
-oxidiazol; N-isopropylcarbazole; triphenylpyrrol; 4,5
-diphenylimidazolidione; 4,5-diphenylimidazolidinethione;
4,5-bis-(4l-amino-phenyl)-imidazolidinone; 1,5-dicyanonaphthalene;
l,~-dicyanonaphthalene; aminophtha]Lodinitrile; nitrophthalo-
dinitrile; 1,2,5,6-tetraazacyclooctatetraene-(2,4,6,8);
2-mercaptobenzothiazole-2-phenyl-4-diphenylidene-oxazolone;
6-hydroxy-2,3-di(p-methoxy-phenyl)-benzofurane; 4-dimethylamino
-benzylidene-benzhydrazide; 3,benzylidene-amino-car~azole;
polyvinyl carbazole; (2-nitro-benzylidene)-p-bromo-aniline;
2,4-diphenyl-quinazoline; 1,2,4-triazine; 1,5-diphenyl-3
-methyl-pyra~oline 2-(~'-dimethyI-amino phenyl)-benzoxazole;
3-amino-carbazole; polyvinylcarbazole-trinitro-Eluorenone
charge transfer complex; phthalocyanines and mixtures thereof.
The toner of the instant invention is particularly
suitàble for use as in the yellow toner in the color electro-
photographic imaging processes disclosed in U. S. Patent
3t804,619 and U. 5. Patent 3,909,259, issued September 30,
1975, Joseph Mammino et al. The process disclosed in the ~ -
above-referenced patent specifications are multiple develop-
ment techniques capable of producing color reproductions employ-
ing multiple sequencing of electrophotographic charging,
exposing through ~Eilters and developing steps with three
different color toners. The toners of magenta, cyan and yellow
colors are developed after exposure through green, red and
blue filters, respectively.
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~7416~
In development and transfer of the three colored
toner images, it is necessary that the relationship of the
toners with each be such that they cooperate to produce an
image of good quality. It is apparent ~hat any one of a
number of variables could cause incomplete J improper, or
inadequate development so that color balance is thereby
shifted resulting in an unaccep1:able color print.
A use of the toners oi. the instant invention is
for a sequential three color development proces~ when combined
with a methyl terpolymer coated steel carrier and utilized
in combination with a copper phthalocyanine pigment identified
in the Colour Index as C.I. 74160, C.I. Pigment Blue lS cyan
toner and a mathyl terpolymer coated steel carrier and
anthraquinone dye identified in the Colour Index as C.I.
607lO, C.I. Disperse Red 15 magenta toner and a nickel berry
carrier.
The toners of the instant invention have been found
to be optimum for a sequential three color development
process when combined with a methyl terpolymer coated s~eel
carrier and utilized in combination with a copper tetra-4-
(octadecylsulfonamido~ phthalocyanine pigment available from
GAF Corporation under the designation of Sudan Blue OS, cyan
toner and a methyl terpolymer coated steel carrier; and
2,~-dimethylquinacridone identified in the Colour Index as
C.I. Pigment Red 1?2, magenta toner and a nickel berry carrier.
A sequential color electrophotographic process is
performed by charging a photoconductive member, exposing said
photoconductive~ member to an original to be reproduced through
a filter of one! color thereby selectively discharging said
photoconductive! member, developing the electrostatic image
-2~-
- ~ :
7~ 6
formed thereby with a developer of a complementary color,
said developer being one member of the group consisting of
copper t~tra-4-(octadecylsulfonamido) phthalocyanine pigment,
cyan toner and a methyl terpol~mer coated steel carrier;
Colour Index Pigment Red 122, magenta toner and a nickel
berry carrier; the toner of the instant invention and a
methyl terpolymer coated steel carrier; charging said
photoconductor for a second time and selectively expo~ing
said photoconductor to the same image through a filter
of another primary color, developing the latent electrostatic
image formed thereby with a developer of a complementary color,
said developer being another member selected from the group
consisting of copper tetra-4-(octadecylsulfonamido~
phthalocyanine pigment, cyan toner and a methyl terpolymer
coated steel carrier; Colour Index Pigment Red 122,
magenta toner and a nickel berry carrier; and the toner
of the instant invention and a methyl terpolymer coated
steel carrier; charging said photoconductive member for
a third time, exposing said photoconductor to the same image
through a filter of the remaining primary color and developing
the latent electrostatic image with a complementary developer~
said developer bsing ~he remaining developer of the group
consisting of copper tetra-4-(octadecylsulfonamido)
phthalocyanine pigment, cyan toner and a methyl terpolymer
coated steel carrier; Colour Index Pigment Red 122, magenta
toner and a nickel berry carrier; and the yellow toner of
the instant invention and a methyl terpolymer coated steel
carrier.
The preferred order of development and method
formation of the magenta and cyan toners is as disclosed
~74166
in Example I of aforementioned U. S. Patent No. 3,909,259.
However, any sequence of development of the cyan, magenta
and yellow toners may be used to produce satisfactory prints.
To further define the specifics of the present
invention, the following examples are intended to illustrate
and not limit the particulars of the present system. Parts
and percentages are by weight unless otherwise indicated.
EXAMPLE I
A styrene-n-butylmethacrylate copolymeric
resin is employed with Colour Index Solvent Yellow 29 colorant
so that the colorant comprises three percent of the toner
composition by weight. The mixture is blended in a drum
tumbler for about an hour at about 10 rpm. The material
is then poured into a screw feeder and extruded until
machine equilibrium is established. The extruded strands
are taken up at the rate of about 50 feet per minute and cooled
in a water bath at about 120F followed by forced air drying.
The strands are then cut by a knife device to make pellets
having a diameter in the range of from 1/16 to 1/8 of an
inch. These pellets are then jetted to about 15 microns
average particle size. This toner is then combined with a
methyl terpolymer coated steel carrier as before described,
to provide an electrostatographic developer. The developer
thus produced is employed in an automatic imaging device,
a Xerox Model 720 copier, having a magnetic brush develop-
ment system. The selenium photoconductor is charged,
selectively exposeld, and developed with the yellow developer.
After 25,000 prints are obtained, images continue to be
produced which possess good contrast, high image density
-26-
3L~7~66
and a desirable appearance. The tribo of ~he developer
continues to maintain a high level similar to that as obtained
in Table I.
EXAMPLE II
.
The process as outlined in Example I is again
employed with the exception that 5 p~rcent dye
concentration is employed.
EXAMPLE III
The process as outlined in Example I is again
employed with the exception that a 7 percent dye
loading is employed.
E~MPhE IV
._
The process as outlined in Example I is again
employed with the exception that a styrene resin is
employed.
- EXAMPLE V
.
The process as outlined in Example I is again
parformed with the exception that the nodular nickel
carrier having a pebbled surface commonly referred to as
~ickel berry is ~mployed as described in the above-
re~erenced U. S. Patentc 3,847,604 and 3,767,568.
EXA~ær~ VI
The process as described in Example I is a~ain
performed with the exceptiQn that the yellow developer
obtained is applied to a mylar transparent substrate to
produce a yellow imaged transparency.
EXAMPLE VII
.
A yellow developer as produced in Example I is
substituted for the yellow developer employed in trichromatic
tr~er~ ~r~
-2~-
. ' . . ' , : .
- , . ~ .. . . . . ..
; . .
. ~ . . .. ... . . . .. . . . . .
~C~7~16~
electrophotographic imaging process as described in
Example I of U. S. Patent 3,804,619.
EXAMPLE VIII
A yellow developer as produced in ~xample V is
substituted for the yellow developer employed in trichromatic
electrophotographic imaging process as described in Example I
-of aforementioned U. S. Patent No. 3,909,259.
Although the present examples were specific in
terms of conditions and materials used, any o~ the above
listed typical materials may be substituted when suitable
in the above examples with similar results. In addition to
-the steps used to carry out the process of the present
invention, other steps or modifications may be used if
desirable. In addition, other materials may be incorporated
in the system of the present invention which will enhance,
synergize or otherwise desirably affect the properties of
the systems for ~heir present use.
Anyone skilled in the art will have other modifications
occur to him based on the teachings of the present invention.
These modifications are intended to be encompassed within the
scope of this invention.
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