Note: Descriptions are shown in the official language in which they were submitted.
WU 92/O5a76 PCf/US90/06837
-1-
SOLVATION-BASED CHARGE DIRECTION OF
LIOUID ELECTROPHOTOGRAPHIC DEtIELOPER COMPOSITIONS
Description
Technical Field
The present invention relates generally to the
field of colar electrophotography, and more~particularly
relates to an improved method for charge directing liquid
electrophotographic developer compositions, and to novel
toner and developer compositions produced thereby.
Back round
Preparation of printed images by
electrophotograptxic, or "xerographic'°, processes involves
coating a selected substrate, or xerographic plate
(typically comprised of metal, glass or plastic), with a
photoconductive insulating material such as selenium, and
then providing an electrostatic charge on the
photoconductive surface, e.g., by ionization from a
corona discharge. A light image is then focused onto the
charged surface, which discharges or lowers the potential
of the irradiated areas, while leaving the remainder of
~he surface charged. The electrostatic image so formed
is then made visible by application of a suitable
developing composition, which may be in either dry or
liquid form.
W~3 92/0547b p~/~~gp/~1~,g3~7
-2-
Conventional liquid developer compositions .
comprise a dispersion of pigment particles in an
insulating carrier liquid. Application of such a ,
composition to the substrate carrying the electrostatic
image results in migration of charged pigment particles
to the substrate surface and deposition thereon in
conformance with the electrostatic image. The developed
image is then transferred to another substrate such as
paper. (In some cases, it is desirable to eliminate the
intermediate step of image transfer, i.e., so that the
developed image is directly produced upon the final
surface; see, e.g., U.s. Patent No. 3,052,539 to Greig.)
Liquid developers for use in multicolor image
development are relatively recent, and are comprised of
colorant embedded in a thermoplastic resin core. These
"toner" particles are then dispersed in an insulating
carrier medium as above. Like compositions used in
black-and-white electrophotography, these developer
compositions additionally contain '°charge directors", or
"charge control agents", to control the charge acquired
by the toner particles in the insulating liquid.
When a color image is to be produced
electrophotographically, the above-described charging,
exposure, and development steps are carried out
separately in succession for each of the constituent
colors of the image using a correspondingly colored
toner. In same color printing processes, each of the
color images is transferred from the electrophotographic
member to a print substrate after development and prior
to formation of the next color image. This process,
however, requires extremely accurate registration of the
successive color images on the substrate to which they
are transferred in order to obtain a high-quality
composite image.
~~0 92eosa7~ Pcreus~oeo~s3;
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-3-
Another color printing process, and the process
currently in use commercially, is a four-color liquid
electrophotographic process known as "consecutive color
toning" or "consecutive multicolor image development".
This process involves: (1) charging a photoconductive
("pc") surface; (2) impressing a first latent image on
the surface by exposure through a colored transparency;
(3) developing the image by contacting the pe with a
liquid developer composition of a first color, typically
l0 yellow; and (4) discharging the pc surface. The steps
are then repeated in sequence, typically using magenta,
cyan, and black developer compositions, i.e., the cyclic
process is repeated until the colored image is complete.
There are a number of problems which are
frequently encountered in electrophotographic color
processes. These include: toner instability; background
staining, i.e., the appearance of taper in uncharged,
non-image areas (a problem which. is ubiquitous in zinc
oxide and other positive toner systems); poor image
resolution (i.e., poor edge acuity); poor image density
resulting from insufficient deposition of toner particles
in intended image regions; and "image" or "character"
staining, where a second process color overtones the
first image in regions where portions of the first image
should have been discharged but were not. An additional
problem with current electrophotographic color
development processes is the need for multiple washing
and drying steps during development, e.g., as described
by Alexandrovich et al. in U.S. Patent No. 4,701,387.
3o The inventors therein propose a solution wherein the
developed surface is rinsed with a polar liquid after
each development step. Tt is suggested that applicatiow
of a polar rinse liquid neutralizes and solvates residual
counterions deriving from charge directors and
stabilizers present in the liquid developer. The method
9~V0 92/05A76 PCT/LJ~90/06$37
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is somewhat time-consuming and unwieldy (it is
recommended in the '387 patent that "after each
development step and before the next developer is
applied, the developed image is rinsed.... After
rinsing, the rinse liquid is removed from the
photoconductive element by drying, wiping or other
method..."; see column 2, lines 62-67).
The in~~ention herein now provides a novel
method for charge directing liquid electrophotographic
developer compositions which addresses the aforementioned
problems. The invention is premised on the generation of
an extremely stable charge director/toner complex, which
in turn provides a very stable developer composition of
exceptionally high particle-mediated conductivity and
charge. The present method and associated compositions
provide for a streamlined development process and enable
preparation of a final electrophotographic print of unex-
pectedly high quality.
2 0 ' Backc rt ound Art
Electro~ahotocrrat~hic x~rocessinrl~enerally:
R.M. Schaffert, Electro~hotoc~rat~hy (London: Focal Press,
1975), provides a comprehensive overview of
electrophotographic processes and techniques.
Representative references which relate to the field of
color electrophotography, specifically, include U.S.
Patent Nos. 3,060,021 to Greig, 3,253,913 to Smith et
al., 3,2$5,837 t0 Neber, 3,337,340 to Matkan, 3,553,093
to Putnam et al., 3,672,887 to Matsumoto et al.,
3,687,661 to Sato et al., and 3,849,165 to Stahly et al.
References which describe electrophotographic toners and
developers include U.S. Patent Nos. 4,659,640 to Santilli
(which describes a developer composition containing
dispersed wax), 2,986,521 to Wielicki, 3,345,293 to
w~ ~z~o~476 gcrms~am~s3;
l f
2092'07
Bartoszewicz et al., 3,406,062 to Michalchik, 3,779,924
to Chechak, and 3,788,995 to Stahly et al.
Charge directors: References which relate to
charge directors include U.S. Patent Nos. 3,012,969 to
van der Minne et al. (polyvalent metal organic salts in
combination with an oxygen-containing organic compound),
3,411,936 to Rotsman et al. (metallic soaps), 3,417,019
to Beyer (metallic soaps and organic surface active
agents), 3,788,995 to Stahly et al. (various polymeric
i0 agents), 4,170,563 to Merrill et al. (phosphonates),
4,229,513 (quaternary ammonium polymers), 4,762,764 to Ng
(polybutene succinimide, lecithin, basic barium petroleum
sulfonates, and mixtures thereof), and Research
Disclosure, May 1973, at page 66.
Image staining in consecutive color toning:
U.'S. Patent No. 4,701,387 to Alexandrovich et al.,
discussed in the preceding section, and U.S. Patent No.
3,337,340 to Matkan, are relevant insofar as each of
these references relates to the problem of image staining
in~consecutive color toning.
'toner resins: U.S. Patent No. 3,806,430 to
Sato et al. describes the use of thermosetting binder
resins such as polyisocyanate-cured alkyd resins, epoxy
ester resins and copolymers of a vinyl monomer and
styrene, acrylic and methacrylic esters or the like,
alkyd resins cured with melamine formaldehyde, or
benzoguanimine formaldehyde, drying oil modified alkyd
resins, and epoxy ester resins cured with a catalyst.
U.S. Patent No. 3,779,924 to Chechak describes alkyd and
modified alkyd resins (e.g., soya oil-modified and
linseed oil-modified alkyds) and phenolic and modified
phenolic resins (phenol formaldehyde resins and
derivatives thereof). U.S. Patent No. 4,845,003 to Kiriu
et al. describes the use of acrylic, styrene-butadiene,
epoxy, and polyester resins. U.S. Patent No. 3,345,293
° WO 92/05475 PCT/t,'S~9U106~3;
_6-
to Bartoszewicz et al. describes a rosin-modified phenol- .
formaldehyde resin, a polystyrene-based resin, and an
epoxy resin. U.S. Patent No. 3,411,936 to Roteman et al.
describe resinous binders that are preferably
"substantially uncharged" (col. 2, line 70). U.S. Patent
No. 3,788,995 to Stahly et al. describe toner resins
containing polar moieties such as sulfoalkyl acrylate,
sulfoalkyl methacrylate, and the like. U.S. Patent No.
4,229,513 to Merrill et al. describes halogenated
polymers designed to serve as negatively charged binder
resins. U.S. Patent No. 4,762,764 to Ng et al. describe
thermoplastic toner resins such as poly(methyl
methacrylate), poly(methyl acrylate), poly(ethyl
methacrylate), and the like.
Surface-bound golvmers: U.S. Patent No.
4,925,766 to Elmasry et al. describes a developer
composition in which ion exchange polymers are bound to
the surface of the dispersed toner particles, and wherein
the chelation sites on the polymers are apparently
designed to complex with a charge director present in thle
carrier liquid. U.S. Patent No. 4,946,753 to Elmasry et
al. also describes such ion exchange resins used in
conjunction with toner.
Disclosure of the Lnvention
Accordingly, it is a primary object of the
invention to address the above-mentioned deficiencies of
the prior art.
It is another object of the invention to _
provide a solvation-based method of providing charge on
toner particles in a liquid electrophotographic developer
composition.
It is still another object of the invention to
provide a solvation-based method for charging toner
particles in a liquid electrophotographic developer'
Wt5 92/0547b Pf'T/ US90/0683
-7-
composition which involves incorporating into the
resinous phase of the toner particle a material
containing specific solvation sites effective to solvate
a selected metal salt used as the charge director.
It is a further object of the invention to
provide toner fox incorporation into a liquid electro-
photographic develaper composition, wherein the toner is
formulated with a resinous phase containing a material
having such specific salvation sites.
It is still a further object of the invention
to provide a liquid eiectrophotographic developer
composition containing such a toner and charge director
dispersed in an insulating carrier liquid.
Additional objects, advantages and novel
features of the invention will be set forth in part in
the description which follows, and in part will become
apparent to those skilled in the art upon examination of
the following, or may be learned by practice of the
invention.
The above objects are accomplished in
accordance with the present invention by providing a
salvation-based method for charging toner particles in a
liquid electrophotographic developer composition. The
method is premised on the importance of a highly stable,
solvated toner particle/charge director complex. In
contrast to prior art methods wherein toner particles are
charged via simple adsorption of the charge director
(see, e.g., Schaffert, supra, at pages 564-566), proton
transfer, or ion exchange, the present method involves
salvation, that is, charged toner particle complexes are
formed by salvation. This is accomplished by
incorporating a material containing specific solvazion
sites into the resinous phase of the toner. The
salvation sites and the metal salt which serves as the
charge director are both selected so that very stable,
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charged toner complexes are formed, i.e., complexes of
(i) the cationic, metal component of the charge director
and (ii) the toner particle itself.
By way of background, solvation of cations such
as metal ions is characterized by the formation of well-
known aquo-complexes as
+n
M + (r) H2p .= M+n (H2p) r ( 1)
The exothermicity of complex formation and therefore the
formation constant is related to the enthalpies of
hydration (see Table 1, in Part (B) of the Detailed
Description). Although precise thermodynamic values are
not readily available for alcohols, carboxylic acids, and
the like, a parallel correlation exists. As a
consequence, when toner particles are interfaced with
specific charge directors, the following equilibrium
relationships are believed to be applicable:
2 0 I MX := M+ + X- ( 2 )
H
T-OH + M+ ~ T - O : M+ (3)
where X- is the counterion and T the toner particle.
This reaction is the equivalence of hydration of metal
ions from tlhe gas phase. That is, the complexation
(i.e., charge direction) reaction is driven in solvents
of low dielectric by solvation with sites on the toner
particle surface. The most preferred solvation reactions
should be quite exothermic and are characterized by large
negative enthalpy. From inspection of the equation
1~VO 92/05476 YC1'/~IS90/f7683;
2~9~~0~
T.'S - ~1H
log K = - (4)
2.3 RT
as the enthalpy of solvation becomes increasingly
negative, the equilibrium constant K for the solvation
reaction becomes larger. In other words, the formation
of the solvated complex becomes increasingly favorable.
Where ionizable sites are employed on the toner
l0 particle, the reaction described in Equation (3) may
indeed proceed according to the equation
H
T - O : M+ ~ T - OM + H+ ( 5 )
1
loss of particle charge
and result in a loss in developer conductivity and
consequent instability. As will be described in further
detail hereinbelow, addition of the conjugate acid of the
counterion suppresses this event and thus stabilizes the
developer.
In a preferred embodiment, the resinous phase
of the toner is formulated so that it contains a polymer
having the aforementioned solvation sites, which are then
present on the surface of the tenet particle and thus
exposed to and available to solvate charge director in
the liquid developer, Tn an alternative embodiment, the
resinous phase of the toner is formulated such that it
contains monomeric species with such solvation sites,
which may or may not be present in combination with a
solvating polymer. Whether the solvation sites are
present on a manomsric species, a polymeric species, or
both, it must be emphas~.zed that preferred solvating
materials are those which will exothermically solvate the
cationic component of the charge director so as to
CA 02092707 1999-11-19
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maximize the stability of the resulting charged toner complex and minimize the
presence of free, unassociated charge director in solution. Solvation may take
place without any significant ionization of the solvation sites.
In another aspect of the invention, toner is provided which contains,
in its resinous phase, a material containing specific solvation sites as just
described.
In still another aspect of the invention, a developer composition is
provided which contains such toner particles dispersed in an insulating
carrier
liquid together with a selected metal salt to serve as the charge director.
l0 Other .aspects of the invention include: processes for manufacturing
the above-described toner and developer compositions; consecutive color toning
processes making use of solvation-based charge direction; and an
electrophotographic image constituting a composite color print prepared using
the
methods and compositions which will be described in detail herein.
According to a first aspect of the invention, there is provided a
process for providing positive surface charge on toner particles for use in a
liquid
electrophotographic developer composition, comprising preparing, in an
oleophilic, electrically insulating carrier liquid, a dispersion of: (a) toner
particles
comprising a resinous phase containing a colorant, the particles being formed
by
admixing the resinous phase and the colorant at a temperature in the range of
about 70°C to 200"C followed by comminuting the admixture, and (b) a
charge
director comprising a metal salt having a metal ion selected from aluminum,
chromium and ferric and including as a counterion, the anion of an ortho-
hydroxy
aromatic acid, wherein the resinous phase comprises a monomeric or a polymeric
CA 02092707 1999-11-19
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material having specific polar group solvation sites that complex with metal
ions of
the metal salt and comprise solvation sites consisting of hydroxyl groups, and
wherein said charge director and the specific solvation sites are selected
such
that solvation thereof by the material is an exothermic reaction with a 0H
that is
more negative than about -50 kJ/mole, whereby to form by solvation complexes
of
the metal ions with the hydroxyl group solvation sites of the material.
The polymer may be selected from the group consisting of ethylene-
vinyl alcohol copolymers, styrene-allyl alcohol copolymers, cellulose acetate-
butyrate copolymers, hydroxyalkyl acrylate copolymers, and ionomers and
l0 mixtures thereof.
The charge director may be selected such that solvation thereof by
the material is an exothermic reaction with a DH that is more negative than
about
-100 kJ/mole or more negative than about -500 kJ/mole.
The charge director may further comprise a salicylic acid anion or a
salicylic acid derivative anion in which the salicylic acid is substituted
with one to
four substituents independently selected from the group consisting of lower
alkyl
having from 1 to 6 carbons, lower alkoxy having from 1 to 6 carbons, halogen,
amino, hydroxy, nitro and sulfonate.
The charge control agent may have the formula (RO-)XM+n(AA-)Y in
which: M is a metal atom selected from aluminum, chromium and iron; AA-
represents an ortho-hydroxy aromatic acid anion; R is selected from the group
consisting of R'CO--, C,-C,4 alkyl, and a 1-3 ring aryl moiety optionally
substituted
with 1-6 carbon atonn alkyl substituents, where R' is C,-C,4 alkyl; n is 2 or
3 where
M is chromium and n is 3 where M is aluminum or iron; and x and y are integers
CA 02092707 1999-11-19
- l Ob
the sum of which is equal to n.
According to a second aspect of the invention, there is provided
positively charged toner complexes comprising: (a) toner particles of a
resinous
phase containing colorant, the particles being formed by admixing the resinous
phase and the colorant at a temperature in the range of about 70°C to
200°C
followed by comminuting the admixture, associated with (b) a charge director
comprising a metal salt having a metal ion selected from aluminum, chromium
and
ferric and including, as a counterion, the anion of an ortho-hydroxy aromatic
acid,
wherein the resinous phase comprises a polymeric or a monomeric material
l0 having specific polar group solvation sites that complex with metal ions of
the
metal salt and comprise solvation sites consisting of hydroxyl groups, and
wherein
the charge director and the specific solvation sites are selected such that
solvation of the charge director by the material is an exothermic reaction
with a
0H that is more neclative than about -50 kJ/mole and the charge director metal
ions form complexes with the hydroxyl group solvation sites of the material.
The charge director may be selected such that solvation thereof by
the material is an e~c:othermic reaction with a DH that is more negative than
about
-100 kJ/mole or more negative than about -500 kJ/mole.
According to a third aspect of the invention, there is provided an
2o electrophotographic image constituting a composite colour print,
comprising,
deposited on a substrate in a predetermined pattern, a toner complex as
described above.
The charge director may further comprises a salicylic acid anion or a
salicylic acid derivative anion in which the salicylic acid is substituted
with one to
CA 02092707 1999-11-19
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four substituents independently selected from the group consisting of lower
alkyl
having from 1 to 6 carbons, lower alkoxy having from 1 to 6 carbons, halogen,
amino, hydroxy, nitro and sulfonate.
The charge director may have the formula (RO-)XM+n(AA-),, in which:
M is a metal atom selected from aluminum, chromium and iron; AA- represents an
ortho-hydroxy aromatic acid anion; R is selected from the group consisting of
R'CO--, C,-C,s alkyl, and a 1-3 ring aryl moiety optionally substituted with 1-
6
carbon atom alkyl substituents, where R' is C,-C,a alkyl; n is 2 or 3 where M
is
chromium and n is 3 where M is aluminum or iron; and x and y are integers the
sum of which is equal to n.
According to a fourth aspect of the invention, there is provided a
positively charged electrophotographic developer composition comprising,
dispersed in an oleophilic, electrically insulating carrier liquid, (a) toner
particles
of a resinous phasE~ containing colorant, the particles being formed by
admixing
the resinous phase and the colorant at a temperature in the range of about
70°C
to 200°C followed by comminuting the admixture, and (b) a charge
director
comprising a metal ion selected from aluminum, chromium and ferric and
including, as a counterion, the anion of an ortho-hydroxy aromatic acid,
wherein
the resinous phase is comprised of a polymeric or a monomeric material having
specific polar group solvation sites that complex with metal ions of the metal
salt
and comprise solvation sites consisting of hydroxyl groups, and wherein the
charge director and the specific solvation sites are selected such that
solvation of
the charge director by the material is an exothermic reaction with a DH that
is
more negative than about -50 kJ/mole and the charge director metal ions form
CA 02092707 1999-11-19
- lOd -
complexes with the hydroxyl group solvation sites of the material.
The polymer may be selected from the group consisting of ethylene-
vinyl alcohol copolymers, styrene-allyl alcohol copolymers, cellulose acetate-
butyrate copolymers, hydroxyalkyl acrylate copolymers, and ionomers and
mixtures thereof.
The colorant may comprise an organic dye or a colored pigment.
The metal ion may be present in the form of a metal salt having the
formula (RO-)XM+n(,AA-),, in which: M is a metal atom selected from aluminum,
chromium and iron; AA- represents an ortho-hydroxy aromatic acid anion; R is
l0 selected from the group consisting of R'CO--, C,-C,s alkyl, and a 1-3 ring
aryl
moiety optionally substituted with 1-6 carbon atom alkyl substituents, where
R' is
C,-C,4 alkyl; n is 2 or 3 where M is chromium and n is 3 where M is aluminum
or
iron; and x and y arE; integers the sum of which is equal to n.
M may be aluminum and AA- may be diisopropyl salicylate.
The charge director may further comprises a salicylic acid anion or a
salicylic acid derivative anion in which the salicylic acid is substituted
with one to
four substituents independently selected from the group consisting of lower
alkyl
having from 1 to 6 carbons, lower alkoxy having from 1 to 6 carbons, halogen,
amino, hydroxy, nitro and sulfonate.
The amount of solvation sites which do not ionize during normal
storage and use may constitute at least 90% of said solvation sites.
Accorcling to a fifth aspect of the invention, there is provided a
process for developing an electrostatic charge pattern using a consecutive
color
toning system, comprising: (a) forming an initial negative electrostatic
charge
CA 02092707 1999-11-19
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pattern on a substrate and developing the initial pattern with a positively
charged
liquid developer composition comprising, dispersed in an oleophilic,
electrically
insulating carrier liquid, (i) toner particles of a resinous phase containing
a first
colorant, the particles being formed by admixing the resinous phase and the
colorant at a temperature in the range of about 70°C to 200°C
followed by
comminuting the admixture, and (ii) a charge director comprising a metal ion
selected from aluminum, chromium and ferric and including, as a counterion,
the
anion of an ortho-hydroxy aromatic acid, (b) forming a second electrostatic
charge
pattern on the substrate and developing the second pattern with a positively
charged liquid developer composition comprising, dispersed in an oleophilic,
electrically insulating carrier liquid, (i) toner particles of a resinous
phase
containing a second colorant, the particles being formed by admixing the
resinous
phase and the colorant at a temperature in the range of about 70°C to
200°C
followed by comminuting the admixture, and (ii) a charge director comprising a
metal ion selected from aluminum, chromium and ferric and including, as a
counterion, the anion of an ortho-hydroxy aromatic acid, wherein steps (a) and
(b)
are conducted in immediate succession without any additional processing steps
therebetween, wherein the resinous phase comprises a polymeric or a monomeric
material having specific polar group solvation sites that complex with metal
ions of
the metal salt and comprise solvation sites consisting of hydroxyl groups, and
wherein the charge director and the specific solvation sites are selected such
that
solvation of the charge director by the material is an exothermic reaction
with a
0H that is more negative than about -50 kJlmole and the charge director metal
ions form complexes with the hydroxyl group solvation sites of the material.
CA 02092707 1999-11-19
- 1 Of -
The process may further comprise repeating steps (a) and (b) with
third and fourth colorants to provide a developed image.
The process may further comprise transferring the developed image
to a surface of a selected substrate so as to give rise to an
electrophotographic
color print thereon.
According to a sixth aspect of the invention, there is provided a
process for providing positive surface charge on toner particles for use in a
liquid
electrophotographic developer composition, comprising preparing, in an
oleophilic, electrically insulating carrier liquid, a dispersion of: (a) toner
particles
to comprising a resinous phase containing a colorant; (b) a charge director
comprising a metal salt having a metal ion selected from aluminum, chromium
and
ferric, wherein the resinous phase comprises a monomeric or a polymeric
material
having a plurality of specific polar group solvation sites that complex with
metal
ions of the metal salt and comprise solvation sites consisting of the
carboxylic acid
moiety -COOH, and wherein said charge director and the specific solvation
sites
are selected such that solvation thereof by the material is an exothermic
reaction
with a 0H that is more negative than about -50 kJ/mole; and (c) an organic
acid in
an amount effective to force the equilibrium of ionization of the carboxyl
groups
substantially toward the non-ionized form.
The anion of said acid may comprise the same anion as an anion of
the charge director.
According to a seventh aspect of the invention, there are provided
positively charged toner complexes comprising: (a) toner particles of a
resinous
phase containing colorant, associated with (b) a charge director comprising a
CA 02092707 1999-11-19
- l Og -
metal ion selected from aluminum, chromium and ferric, wherein the resinous
phase comprises a polymeric or a monomeric material having specific polar
group
solvation sites that complex with metal ions of the metal salt and comprise
solvation sites consisting of the carboxylic acid moiety -COOH, and wherein
the
charge director and the specific solvation sites are selected such that
solvation of
the charge director by the material is an exothermic reaction with a 0H that
is
more negative than about -50 kJ/mole and (c) an organic acid in an amount
effective to force the equilibrium of ionization of the carboxyl groups
substantially
toward the non-ionized form.
l0 The anion of said acid may comprise the same anion as an anion of
the charge director.
According to an eighth aspect of the invention, there is provided a
positively charged electrophotographic liquid developer composition
comprising,
dispersed in an oleophilic, electrically insulating carrier liquid, (a) toner
particles
of a resinous phase containing colorant, (b) a charge director comprising a
metal
ion selected from aluminum, chromium and ferric, wherein the resinous phase is
comprised of a polymeric or a monomeric material having specific polar group
solvation sites that complex with metal ions of the metal salt and comprise
solvation sites consisting of the carboxylic acid moiety -COOH, and wherein
the
charge director and the specific solvation sites are selected such that
solvation of
the charge director by the material is an exothermic reaction with a 0H that
is
more negative than about -50 kJ/mole and (c) an organic acid in an amount
effective to force the equilibrium of ionization of the carboxyl groups
substantially
toward the non-ionized form.
CA 02092707 1999-11-19
- l Oh -
The anion of said acid may comprise the same anion as an anion of
the charge director.
The charge control agent may have the formula (RO-)xM+n(AA-),, in
which: M is a metal atom selected from aluminum, chromium and iron; AA-
represents an ortho-hydroxy aromatic acid anion; R is selected from the group
consisting of R'CO--, C,-C,5 alkyl, and a 1-3 ring aryl moiety optionally
substituted
with 1-6 carbon atom alkyl substituents, where R' is C,-C,4 alkyl; n is 2 or 3
where
M is chromium and n is 3 where M is aluminum or iron; and x and y are integers
the sum of which is equal to n.
l0 The charge director may further comprise a salicylic acid anion or a
salicylic acid derivative anion in which the salicylic acid is substituted
with one to
four substituents independently selected from the group consisting of lower
alkyl
having from 1 to 6 carbons, lower alkoxy having from 1 to 6 carbons, halogen,
amino, hydroxy, nitro and sulfonate.
Modes for Carrying Out the Invention
A. Definitions
"Toner" as used herein is intended to denote the resinous, colored
particles (referred to~ sometimes herein as "toner particles") which
ultimately form
the electrophotographic image on the photoconductive (pc) surface.
By "developer composition" as used herein is meant a dispersion of
toner and charge director in a selected insulating carrier liquid. The
developer
composition may contain a number of additional components as will be described
below.
WC) 92/054?6 PC1'/~J~9t31f~683?
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"Particle-mediated" conductivity and charge is
intended to mean that virtually all of the conductivity
and charge in a developer composition derive from the
charged toner particles and not fram free, unassociated
salts which may be present in solution (i.e., from
unassaciated charge director or other ionizable species).
The developer compositions of the invention display very
high partials-mediated conductivity and charge and very
low continuous phase conductivity.
"Consecutive color toning°° as used herein is
intended to mean an electrophotographic development
process involving repetition of charging and development
steps with more than one color (as outlined in the
Background Section abave) so as to provide a multicolor
final image. The process is also sometimes referred to
herein as "consecutive multicolor image development°°.
"Background staining" is a problem which can
arise in any electrophotographic process. As used herein
the term has its art-recognized meaning and refers to the
problem wherein toner appears in unintended, uncharged, i
non-image areas.
"Image staining" is a problem which is specific
to consecutive color toning, and similarly has its art-
recognized meaning as used herein. The problem involves
overtoning by a second or subsequent process color of an
earlier color image in regions where portions of the
earlier image should have been discharged but were not.
"Image staininr~°' is also sometimes referred to herein and
in the art as "character staining".
By ''specific solvation sites" is meant moieties
present in a material contained within the toner resin
and effective to solvate the metal salt or salts which
will serve as the charge director. "Salvation" is used
according to its conventional meaning, i.e., to indicate
the association or combination of a salute unit (the
wc~ ~ziosa7s p~-ri~sgo>o6s~7
zo~~~o~
-12-
charge director, in the present case) with a solvent
species (the solvation sites on the toner surface
herein). See, e.g., The McGraw-Hill Encyclovpedia of
Science and Technoloc~y, New Xork: McGraw-Hill, 1987. As
discussed therein, solvation may involve chemical or
physical interaction, or both, and may vary in degree
from a loose complex to a distinct, tightly complexed
structure. In the present invention, the solvation sites
in the charge director are preferably selected such that
solvation of the charge director is a highly exothermic
process and gives rise to a very stable, charged toner
particle.
By "carboxyl" as used herein is meant the
carboxylic acid moiety -COOH.
B. Overview of the Novel Method:
As noted above, the focus of the present
invention is on a solvation-based mechanism for providing
charge on toner particles contained in a liquid
electropho~ographic developer composition.
The present invention thus involves a novel
method of creating very stable charge director/taner
complexes. As explained in co-pending, commonly assigned
U.S. Patent Application Serial No. 07/464,896,
incorporated by reference above, the stability of the
charge director/toner complex has been found to be of the
utmost importance in liquid electrophotography. In the
'896 application, the focus was on the use of toners
containing surface ion exchange sites effective to form
extremely stable, ionic complexes with the metal salts
that serve as the charge director. In the present
application, the focus is on a solvation interaction,
i.e, the cationic, metal component of the charge director
is complexed via solvation to the surface of the toner
particle. As explained in the '896 application, if the
WVO 92JOS~i76 PCf/ US9f)/Ub83 7
-13-
2~92'~~~
toner and the cationic component of the charge director
are such that complexation between the two components is
heavily favored, as here, virtually all of the charge
director will be present in complexed form, and there
will be substantially no unassociated charge director in
solution. In the present case, the solvation sites and
the charge director are selected such that solvation is a
highly exothermic process, giving rise to an extremely
stable complex. Examples of particular toner materials
and charge directors which may be used in this manner, to
provide an extremely stable charged toner particle, are
set out in Part (C) of this section.
In general, the solvation sites may derive from
one or more polymers and/or one or more monomeric species
incorporated into the toner resin. Indeed, the toner
resin itself may be a polymer containing the~desired
solvation sites. Exceptional solvation sites are those
which, as noted above, will not ionize to any significant
degree under the conditions of ordinary storage and use.
of the liquid electrophotographic developer. If
ionizable solvation sites are present, e.g., carboxyl
groups, it is preferred that 'the charge director be
either a pH-neutral salt (i.e., a metal salt of a strong
acid) or a salt that contains a self-stabilized
counterion, as will be described in the next section.
Also, if such ionizable moieties are used as solvation
sites, it is preferred that a small amount of acid,
preferably the acid form of the charge director's
counterion, be added into the developer composition to
force equilibrium towards the non-ionized form of the
specie] (in the case of a carboxyl group, the added acid
will thus give rise to cOOH groups as opposed to the
ionized COO- species).
The charge director should also be selected
with a view towards maximizing the stability of the
W~ 92/05476 fCI'/~1590/0683~
-14-
"solvated" charged toner particle complex. More
specifically, the charge director should be a metal salt
containing a metal ion which will give rise to a highly
exothermic solvation interaction with the aforementioned
solvation sites. The preferred metals are generally
those which have large negative enthalpies of hydration.
The following table illustrates the enthalpies of
hydration of some ions:
Enthalpies of H~dration* of Some Tons (kJ mol-1~~
H~ -1091 Ca2~ °1577 Cd2~ -1807
Li+ -519 Sr2~~ -1443 Hg2+ -1824
Na+ -406 Ba2+ -1305 Sn2+ -1552
K+ -322 ~ Cr2+ -1904 Pb2+ -1481
Rb+ -203 Mn2+ -1841 A12~ -4665
Cs~ -264 Fa2~ -1946 Fe3~ -4430
Ag+ °473 Co2* -1996 F -515
Tl+ -326 Ni2+ -2105 C1 -381
Be2~ -2494 Cu2~' -2100 Br -347
Mg2+ -1921 Zn2+ -2046 I- -305
*Absolute values are based an the assignment of -1091 ~
10 kJ mol 1 to H~ (cf. H.F. Halliwell and S.C. Nyburg,
Trans. Faraday Soc., 1963, X9:1126). Each value probably
has an uncertainty of at least lOn kJ mol 1, where n is
the charge of the ion.
(F. A. Cotton and G. Wilkinson, Advanced Inorganic
Chemistry, New York: John Wiley & Sons, 1972.)
The present invention involves solvation by '
materials other than water, and thus does not involve
hydration as such. Enthalpies of solvation will,
however, typically correlate with these enthalpies of
W(J 92/~S~b76 PCT/U590/06837
-15-
hydration. The enthalpy of solvation here (i.e., of the
cationic, metal component of the charge director by the
solvation sites) is generally a large negative value
(i.e., the solvation reaction involves an enthalpy of
solvation that is more negative than about -50 kJ/mole,
preferably mare negative than about -100 kJ/mole, most
preferably more negative than about -500 J/mole). As may
be deduced from the above table, small, highly charged
metal ions give rise to the most exothermic hydration or
solvation reactions. (See the CRC Handbook of Chemistry
and Physics, 6?th Ed., at page F-157.) Such metals are,
accordingly, preferred charge directors for use in
conjunction with the present invention.
Selection of toner salvation sites and a charge
director that will give rise to a very stable toner/
charge director complex in turn enables preparation of a
liquid developer composition in which (1) virtually all
of the solution's conductivity and charge derives from
the toner particles, (2) the toner is highly charge-
stabilized, i.e., will retain charge over a prolonged
period of time, and (3) the toner particles are
themselves highly charged. As emphasized throughout this
application, these features yield a final image of
exceptionally high quality, i.e., with respect to image
density, edge acuity, and the like, and also enable use
of the toner in a consecutive color process without need
for intermediate processing steps which have heretofore
been necessary to remove residual toner in unwanted,
"non-image" areas.
C. Novel Toner and Develouer Com~aositions:
In addition to the aforementioned method, the
present invention encompasses novel toner and developer
compositions. The novel toner is useful for formulating
a liquid developer composition in which conductivity and
.
~U ~ziosa~~ P~ri~~~r~ioss3;
-16-
charge are both substantially particle-mediated, as .
explained above. As with currently available toner
compositions, the toner of the invention includes two ,
basic components: (a) resin; and (b) colorant. In
contrast to the toners of the prior art, however, the
present invention involves, as noted above, the
incorporation of a material containing specific solvation
sites into the rsainous phase of the toner particle.
Materials which may be incorporated into the
resinous phase of the toner particle, as discussed in the
preceding section, may be either monomeric or polymeric
or both. ,
Preferred monomeric species are those which
contain polar moieties as the solvation sites, e.g.,
sulfhydryl groups, amines, or oxygenic moieties such as
hydroxyl groups, carboxyl groups, ketones, amides, and
ethers. Most exceptional, however, are hydroxyl
containing monomeric species. Examples of monomeric
species which may be incorporated into the toner resin to
provide such specific solvation sites include sugars,
e.g., mannitol, sorbitol, xylitol and the like.
It is generally preferred herein that the
material containing specif is solva.tian sites be
polymeric. Preferred polymers,~l'_ke preferred monomers,
are those which contain as the specific solvation sites
hydroxyl groups, sulfhydryl groups, carboxyl groups,
ketones, amides, ethers, and/or amines. An example of a
class of polymers useful herein which contain ketone
moieties as the specific solvation sites are acrylates.
3.0 An example of an amide-containing polymer is nylon, while
an exemplary ether-containing polymer is polyethylene
oxide. An example of an amino-containing polymer for use
herein is polyvinyl pyridine. Examples of particularly
preferred polymers for use. herein are ethylene-acrylic
acid copolymers, ethylene-vinyl alcohol copalymers,
~w ~zia~a~~ pc-rius~aia~s3%
2~~~'~0'~
styrene-allyl alcohol copolymers, cellulose acetate-
butyrate copolymers, hydroxyalkyl acrylate copolymers,
and ionomers and mixtures thereof. It will be
appreciated by those skilled in the art, however, that a
wide range of polymeric materials may be used herein, so
long as the selected material enables solvation of the
charge director to give a highly stable toner/charge
director complex, and does not interact in a deleterious
manner with any of the other components of the developer
composition.
It is generally preferred that the materials
containing specific solvation sites be noel-ionized under
the conditions used in electrophotographic development,
i.e., such that at least about 80%, more preferably at
least about 90%, and most preferably at least about 95%,
of the solvation sites are not ionized during ordinary
conditions of storage and use. Where the solvation sites
are readily ionizable species, such as carboxyl groups,
again, as noted above, it is preferred that additional
acid be included in the developer composition so that the
ionization of the carboxyl groups is suppressed.
Typically, this will involve adding the acid form of the
charge director counterion. For example, where the
charge director counterion is diisopropylsalicylate
z5 (DIPS), one would add a sufficient quantity of
diisopropylsalicylic acid to force the equilibrium to the
point where the carboxylic acid groups are in
substantially un-ionized form.
As will be pointed out below, it is also
desirable, to ensure the formation of a stable toner/
charge director complex, that the metal ion which serves
as the cationic component of the charge director is one
that will be solvated exothermically by aforementioned
material, e.g., aluminum; magnesium, chromium, iron, or
the like. Preferred metals are those which have very
CA 02092707 1999-11-19
-18-
negative enthalpies of hydration and thus, herein, give
rise to an enthalpy of solvation that is more negative
than about -500 kJ/mol, more preferably more negative
than about -1000 kJ/mol. Such values will give rise to a
charged toner complex which is extremely stable, in turn
enabling preparation of a liquid developer composition
having a virtually indefinite shelf-life. This aspect of
the invention represents a tremendous advantage relative
to currently available developer compositions, which can
be relatively unstable and have a finite shelf-life.
The colorants which may be used in the toner
can include virtually any pigments, dyes or stains which
may be incorporated in the toner resin and which are
effective to make visible the electrostatic latent image.
Examples of suitable colorants include: Phthalocyanine
blue (C. I. 74160), Diane blue (C. I. 21180), Milori blue
(an inorganic pigment equivalent to 1 ramarine) as cyan
colorants; Brilliant carmine 6B (C. I. 15850), Quina-
cridone magenta (C. I. Pigment Red 122) and Thio indigo
2o magenta (C. I. 73310) as magenta colorants; benzidine
yellow (C. I. 21090 and C.I. 21100) and Hansa Yellow (C. I.
11680) as yellow colorants; organic dyes; and black
materials such as carbon black, charcoal and other forms
of finely divided carbon, iron oxide, zinc oxide,
titanium dioxide, and the like. It should also be noted
that the polymers for use in conjunction with the present
invention tend to dissolve the aforementioned pigments
and dyes readily and are thus quite advantageous in that
regard.
The developer compositions of the invention
contain the aforementioned toner, together with a
selected charge director, as described above, dispersed
in an insulating carrier liquid.
One class of metal salts useful as charge
directors
CA 02092707 2000-07-31
-19-
include as a counterion the intramolecularly stabilized
anion of an ortho-hydroxy aromatic acid, e.g., salicylic
acid or a derivative thereof. By a salicylic acid
"derivative" applicant intends to include salicylic acid
substituted with one to four, typically one to two,
substituents independently selected from the group
consisting of lower alkyl (1-6C), lower alkoxy (1-6C),
halogen, amino, hydroxy, nitro and sulfonate.
These charge directors may typically be
represented by the formula (RO )xM+n(AA )y in which M is
a metal atom, AA represents the anion of the ortho-
hydroxy aromatic acid, and R is selected from the group
consisting of R'CO-, C1-C15 alkyl, n is 2, 3 or 4, and x
and y are integers the sum of which, clearly, is n. The
metal atom "M" may be divalent, trivalent or tetravalent,
with those metal atoms that will coordinate most strongly
with the toner resin being preferred. (In one
particularly exemplary embodiment, AA is diisopropyl
salicylate (DIPS), R is C10H21C0- (i.e., R' is C10H21)' n
is 3, x is 1 or 2, and y is 1 or 2.)
A second class of charge directors useful
herein
are of the formula
(X )aM+n(AA )b in which M is a metal atom as described
above, AA represents the anion of an ortho-hydroxy
aromatic acid
, X represents the
anion of an a,~-diketone, n is 2, 3 or 4, and a and b are
integers the sum of which is equal to n, with the proviso
that neither a nor b is 0.
CA 02092707 1999-11-19
-20-
The
anion X represents the anion of an a,8-diketone, one
which preferably has the formula:
O
R1_ IC_CH2 _ IC_R2
wherein R1 and R2 are independently selected from the
group consisting of hydrogen, alkyl, alkenyl, alkynyl,
cycloalkyl, haloalkyl, aryl, alkaryl, and haloaryl. If
alkyl, alkenyl, alkynyl, cycloalkyl, or haloalkyl, the
substituent preferably contains from about 1 to about 12
carbon atoms, more preferably from about 1 to about 6
carbon atoms (wherein the latter type of moiety is
sometimes referred to herein as "lower" alkyl, akenyl,
alkynyl, etc.). If aryl, alkaryl, or haloaryl, the
substituent preferably contains one to about three rings,
more preferably, one to two rings, and most preferably is
monocyclic. An example of a particularly preferred a,B-
diketone is acetyl acetone, i.e., wherein R1 and R2 are
both methyl.
The developer compositions of the invention
contain toner and developer dispersed in an electrically
insulating carrier liquid as well-known in the art. The
liquid is typically oleophilic, stable under a variety of
conditions, and electrically insulating. That is, the
liquid has a low dielectric constant and a high
electrical resistivity so as not to interfere with
development of the electrostatic charge pattern. Pref-
erably, the carrier liquid has a dielectric constant of
less than about 3.5, more preferably less than about 3,
and a volume resistivity greater than about 109 ohm-cm,
more preferably greater than about 1010 ohm-cm. Examples
of suitable carrier liquids include halogenated
hydrocarbon solvents such as carbon tetrachloride,
trichloroethylene, and the fluorinated alkanes, e.g.,
~'~ ~z~~~~7~ ~crms~oiubs~;
-21-
trichloromonofluoromethane and trichlorotrifluoroethane
(sold under the trade name "Freon" by the DuPont
Company); acyclic or cyclic hydrocarbons such as
cyclohexane, n-pentane, isooctane, hexane, heptane,
a decane, dodecane, tetradecane, and the like; aromatic
hydrocarbons such as benzene, toluene, xylene, and the
like; silicone oils; molten paraffin; and the paraffinic
hydrocarbon solvents sold under the names Isopar G,
Isopar H, Isopar K and Isopar 1. (trademarks of Exxon
y0 Corparation). The foregoing list is intended as merely
illustrative of the carrier liquids which may be used in
conjunction with the present invention, and is not in any
way intended to be limiting.
15 C. Toner and Developer Manufacture:
Toner is prepared by admixing resin and
colorant at an elevated temperature, followed by dry
camminution. The intermediate particles so provided are
then subjected to liquid attrition to give the final
20 toner particles. The'following exemplifies such a
process:
Resin and colorant are admixed at a temperature
in the range of about 70°C to 200°C. A two-roll mill, an
extruder, an intensive mixer or the like; is used to
25 ensure complete mixing. The admixture is then comminuted
dry., i.e., without addition of liquid, to give
intermediate particles typically averaging 30 mils in
diameter or less. This dry comminution step is carried
out in a jet mill, a hammer mill, or the like. The
30 intermediate particles so obtained are then subjected to
liquid attrition in a selected attrition liquid to give
the final toner particles. The liquid used for attrition
is typically selected from the same class of liquids
useful as the carrier liquid for the developer
35 composition, as will be described below.
CA 02092707 1999-11-19
-22-
The developer compositions of the invention
-- prepared by dispersion of toner and charge director in
the insulating carrier liquid -- can contain additional
materials, e.g., an incompatible phase such as a wax,
which is preferably incorporated into the toner at the
initial stage of manufacture, i.e., admixed with the
colorant, resin, etc., in step (a)
The developer can
also contain an antistain agent to reduce the problem of
background staining, as discussed in the parent
application hereto; again, the antistain agent is
preferably incorporated into the composition at the stage
of toner manufacture. The developer composition can also
contain other materials as known in the art, e.g.,
dispersants, stabilizers and the like.
D. Consecutive Multicolor Imaae Develon~ment:
Briefly, a consecutive multicolor image
development process (or a "consecutive color toning"
process) using the materials of the invention may be
carried out a.s follows.
The: surface of a photoconductive insulating
layer on a relatively conductive substrate is charged,
and an initial electrostatic charge pattern (or "latent
image") is formed on that surface~by exposure through a
colored transparency. This latent image is then
developed with a liquid developer composition of a first
color, i.e., comprising toner formulated with a first
colorant, typically yellow. The photoconductive layer is
then discharged, either optically or non-optically, i.e.,
via a corona. These steps are then repeated in sequence
with developer compositions of different colors,
typically (in order) magenta, cyan and black, at which
point the developed image may, if desired, be transferred
to another substrate, e.g., paper. Using the toner and
~3~0 92/04?G PCl'/U~'90/~b83?
~0~270'~
_23_ _
developer compositions of the invention, i.e.,
compositions which involve a solvation interaction
between the surface of the toner particles and the
incorporated charge director, it is possible to carry out
.. the aforementioned sequence of steps without any
intermediate processing steps, i.e., rinsing, drying or
the like. These steps have typically been necessary in
the prior art, as exemplified by the Alexandrovich et al.
patent, cited supra, to address the problem of image
staining.
As illustrated by the above disclosure and the
examples which follow, the compositions and processes of
the invention address and overcome a number of
significant obstacles heretofore present in color
electrophotographic image develogment.
The following examples illustrate preparation
and use of materials in conjunction with the compositions
and processes of the invention.
WO 92/x5476 P~.'T/~IS90/06f337
2~~-2'~ ~"~ -24-
Example 1
Two hundred and twenty-five g of RJ-100 (a
styrene-allyl alcohol copolymer obtained from Allied
Chemical Corp., Morristown, New Jersey) were melted at
95°C on a two-roll mill. To the polymer melt was added
32 g of Heliogen Blue, 3 g of Pigment Green 7 and 0.9 g
of Sicofast Yellow D-1155. Mixing was done in 30
minutes, at which time 10 g of carnauba wax was added.
After an additional 15 minutes of mixing the mill was
cooled and the resultant product was removed. This
mixture was cryogenically comminuted an a hammer mill.
Thirty g of this powder were charged into an attritor
with 130 g of Isopar G (Exxon). After 45 minutes, the
attrition was terminated, discharged from the attritor
and diluted with 130 g of Isopar to give a l0%
concentrate.
Forty g of the above concentrate was diluted to
40o g with Isopar G to give 1% ~.aorking developer. To the
latter was added 0.4 g of a 1%~ solution of aluminum
diisopropyl salicylate. The developer thus prepared
exhibited a stable conductivity of 4.1 pmhas, and also
exhibited an excellent shelf-life. This positively
charged developer produced sharp, dense images an Zn0
photoconductors.
Example 2
The procedure of Example 1 was repeated, except
that RJ-100 was replaced with ACX 260, an ethylene vinyl
acetate/vinyl alcohol copolymer (obtained from Allied
Chemical Carp.). Substantially the same results -- with
respect to stable conductivity, shelf-life, and image
quality -- were obtained.
WC) X2/05476 PCT/LJS90/06837
-25-
Example 3
The procedure of Example 1 was repeated, except
that the charge director used, instead of aluminum
diisopropyl salicylate, was chromium octoate.
Substantially the same results -- with respect to stable
conductivity, shelf-life, and image quality -- were
obtained.
Example 4
The procedure of Example 1 was repeated, except
that the charge director used, instead of aluminum
diisopropyl salicylate, was aluminum tri-neodecanoate
(Mooney Chemical). Substantially,the same results
-- with respect to stable conductivity, shelf-life, and
image quality -- were obtained.
Example 5
The procedure of Example 1 was repeated, except
that the charge directar used, instead of aluminum
diisopropyl salicylate, was copper octoate (Mooney
Chemical). Substantially the same results
--. with respect to stable conductivity, shelf-life, and
image quality -- were obtained.
WO 92/0 s47b PCI'/USiO/~6$37
-2b-
Example 6
The procedure of Example 1 was repeated, except
that the charge director used, instead of aluminum
diisopropyl salicylate, was ferric octoate (Mooney
Chemical). Substantially the same results -- with
respect to stable conductivity, shelf-life, and image
quality -- were obtained.
Example 7
The procedure of Example 1 was repeated, except
that the charge director used, instead of aluminum tri-
neodecanoate, was aluminum dinonylnaphthalene sulfonate. '
Substantially the same results -- with respect to stable
conductivity, shelf--life, and image quality -- were
obtained.
Example 8
The procedure of Example 1 was repeated, except
that the charge director used, instead of aluminum
diisopropyl salicylate, was Al(AcAc)(DTPS)2, wherein
"AcAc°' represents acetyl acetonate, and "DIPS" represents
diisopropyl salicylate.
This charge director was prepared as follows.
Aluminum acetyl acetonate (Aldrich Chemical Co., 6.4 g;
0.2 mh) and 8.88 g of diisopropyl salicylic acid (Aldrich
Chemical Co.) were dissolved in 100 g of toluene. The
resultant solution was heated at 95-100°C for 2 hours.
The solvent was removed at 95°C (steambath) in vacuo,
leaving 11.3 g of a viscous glass. The latter was
dissolved in 25 mL of hot acetone. Upon removal of the
Va~~ 92/OS476 fCT/U$9a/Ob837
-27-
acetone in vacuo, a brittle foayn resulted which was dried
at 70°C for 24 hours. For the product C31H4108A1,
[A1(AcAc)(DIPS)2), the theoretical percentage of A1 is
4.75, whale 4.73 was found. The product was readily
soluble in Isopar and conferred a positive charge to
toners at the rate of 10 7-10-5 mole/g toner.
When used in the process described in Example
1, substantially the same results -- with respect to
stable conductivity, shelf-life, and image quality --
were obtained.
Example 9
1S One hundred seventy-five g of ACX 251 (an
ethylene-vinyl alcohol polymer obtained from Allied
Chemical) was melted at 90°C on a two-roll mill. To the
polymer melt was added 31.4 g of Heliogen Blue L 7080,
2.9 g of Heliogen Green (Pigment Green 7), 0.8 g of
Sicofast D-1155, and 6.6 g of WB-11, a cationic wax
dispersant (Petrolite). Mixing was continued for 30
minutes. The mill was cooled and the product removed and
processed to a 10% concentrate as described in Example 1.
To 400 g of 1% working developer was added 0.6
g of a 1% solution of aluminum tri-neodecanoate (Mooney
Chemical). The conductivity was 7.8 pmhos. As in
Example 1, the shelf-life of the developer was quite
superior. This positively charged developer yielded
excellent, dense, high resolution images on Zn0
photoconductors.
WC) 92/0546 f'CT/US90/Ob837
-28-
Example 10
The procedure of Example 9 was repeated, except
that the charge director used, instead of aluminum tri-
neodecanoate, was aluminum diisopropyl salicylate.
Substantially the same .results -- with respect to stable
conductivity, shelf-life, and image quality -- were
obtained.
Exam 1P a 1 ~.
The procedure of Example 9 was repeated, except
that the charge director used, instead of aluminum tri-
neodecanoate, was zirconium di-neodecanoate (P~iooney
Chemical). Substantially the same results --.with
respect to stable conductivity, shelf-life, and image
quality -- were obtained.
Example 12
The procedure of Example 9 was repeated, except
that the charge director used, in:~tead of ~.lumiraum tri-
neodecanoate, was ferric tri-naphLhenate (Nuodex).
Substantially the same results -- with respect to stable
conductivity, shelf-life, and image quality -- were
obtained.
Examble 13
The procedure of Example 9 was repeated, except
that the charge director used, instead of aluminum tri-
neodecanoate, was A1(AcAc)(DIPS)2, wherein '°AeAc°' and
wo 9zio5a7s ~crius9aiass3~
-29-
"DIPS" are defined above. The charge director was
prepared as described in Example 8.
When used in the process described in Example
8, substantially the same results --- with respect to
stable conductivity, shelf-life, and image quality --
were obtained.
Example 14
One hundred twenty g of AC 201 resin (Allied
Chemical) were placed onto a two-roll mill at 100°C. To
the polymer melt was added 52 g of Sicofast D-1155.
After 30 minutes of mixing, 60 g of AC 540 resin (Allied)
and 60 g of AC 7 (Allied) were added. After 15 minutes
of mixing, l0 g of Ethomid HT 60 dispersant (obtained
from Akxo) and 13 g of WB-17 dispersant (Petrolite) ware
added. Mixing was continued far 20 minutes and the
product was discharged and processed to give a 10%
developer as described in Example~l.
To 400 g of 1% developer was added 1 g of 0.05%
aluminum diisopropyl salicylate and 2 g of a 1% solution
of diisopropyl salicylic acid. The conductivity was 3.7
pmhos. This developer -- which, like the developer
z5 compositions of the preceding examples, exhibited a
superior shelf-life -- produced sharp, dense images on
zn0 photoconductors.
w~ gziosa76 ~~rius~oios~3~
--3 0-
Exami7le 15
The procedure of Example 14 was repeated,
except that the charge director used, instead of aluminum
diisopropyl salicylate, was Al(AcAc)(DIPS)2~ wherein
"AcAc'° and "DIPS" are defined above. The charge director
was prepared as described in Example 15.
When used in the process described in Example
30, substantially the same results.
Example 16
The procedure of Example 14 is repeated, except
that Sicofast D-1155 is replaced with Hostaperzn Red E5B-
02. Substantially the same results -- with respect to
stable conductivity, shelf-life, and image quality --
were obtained.
Example 17
The procedure of Example 14 is repeated, except
that Sicofast D-1155 is replaced with Heliogen Blue L-
7080. Substantially the same results -- with respect to
stable conductivity, shelf-life, and image quality --
were obtained.
Example 18
The procedure of Example 14 is repeated, except
that Sicofast D-1155 is replaced with Novaperm Yellow
F~L. Substantially the same results -- with respect to
wo yziosa76 ~crius9oioss3~
2U~2 ~0 l
~31- ... . .
stable conductivity, shelf-life, and image quality --
were obtained.
Example 19
The procedure of Example 14 is repeated, except
that Sicofast D-1155 is replaced with Indofast Brilliant
Scarlet R-6335. Substantially the same results -- with
respect to stable conductivity, shelf-life, and image
quality -- were obtained.
Examz~le 20
The procedure of Example 14 is repdated, except
that Sicofast D-11.55 is replaced with Quindo Magenta
RV6832. Substantially the same results -- with respect
to stable conductivity, shelf-life, and image quality --
were obtained.
Examule 21
The procedure of Example 14 .is repeated, except
that Sicofast D-1155 is replaced with Quindo Red 6713. w
Substantially the same results -- with respect to stable
conductivity, shelf-life, and image quality -- were
obtained.
