U.S. patent number 3,849,165 [Application Number 05/387,875] was granted by the patent office on 1974-11-19 for liquid electrographic development process.
This patent grant is currently assigned to Eastman Kodak Company. Invention is credited to Stewart H. Merrill, Frederick A. Stahly.
United States Patent |
3,849,165 |
Stahly , et al. |
November 19, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
LIQUID ELECTROGRAPHIC DEVELOPMENT PROCESS
Abstract
Liquid developers for electrography are made using addition
polymers containing a polar moiety and at least one additional
moiety having predetermined solubility characteristics with respect
to the carrier liquid. Mixtures of these polymers may also be
used.
Inventors: |
Stahly; Frederick A. (August,
NY), Merrill; Stewart H. (Rochester, NY) |
Assignee: |
Eastman Kodak Company
(Rochester, NY)
|
Family
ID: |
26847094 |
Appl.
No.: |
05/387,875 |
Filed: |
August 13, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
149851 |
Jun 3, 1971 |
3788995 |
|
|
|
Current U.S.
Class: |
430/119.1;
430/114; 430/112 |
Current CPC
Class: |
G03G
9/131 (20130101) |
Current International
Class: |
G03G
9/12 (20060101); G03G 9/13 (20060101); G03g
009/04 (); G03g 013/10 () |
Field of
Search: |
;117/37LE ;96/1LY
;355/10,17 ;118/637,DIG.23 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Sofocleous; Michael
Attorney, Agent or Firm: Rosenstein; A. H.
Parent Case Text
This is a continuation of application Ser. No. 149,851, filed June
3, 1971, and now U.S. Pat. No. 3,788,995.
Claims
We claim:
1. The process of developing electrostatic charge patterns carried
on the surface of an electrographic element comprising the steps of
forming said electrostatic charge patterns on said electrographic
element and contacting said charge patterns with a liquid developer
comprising an electrically insulating carrier liquid having a
dielectric constant less than about 3 and a volume resistivity
greater than 10.sup.10 ohm-cm. and at least one polymer to develop
said charge patterns, said polymer containing at least two
monomeric moieties, at least one of said monomeric moieties being a
polar moiety present in an amount of at least about 1.5 .times.
10.sup.-.sup.4 moles/g. of said polymer and at least one other of
said monomeric moieties being a moiety soluble in said carrier
liquid, said polymer containing a sufficient amount of said soluble
moiety to yield a dispersibility ratio for said polymer in the
liquid carrier greater than about 0.825, and said polar moiety
being selected from the group consisting of:
a. sulfoalkyl acrylates;
b. sulfoalkyl methacrylates;
c. metal salts of sulfoalkyl acrylates;
d. metal salts of sulfoalkyl methacrylates;
e. amine salts of sulfoalkyl acrylates;
f. amine salts of sulfoalkyl methacrylates;
g. metal salts of acids selected from the group consisting of
acrylic and methacrylic acids; and
h. amine salts of acids selected from the group consisting of
acrylic and methacrylic acids;
and mixtures thereof.
2. The process of claim 1 wherein the liquid developer further
comprises a colorant and said polymer contains at least about 35
weight percent of the soluble moiety and less than about 20 percent
by weight of the polar moiety.
3. The process of claim 2 wherein the soluble moiety is selected
from the group consisting of:
a. alkyl styrenes having from about 3 to about 10 carbon atoms in
the alkyl moiety;
b. alkoxy styrenes having from about 3 to about 10 carbon atoms in
the alkyl moiety;
c. alkyl acrylates having from about 8 to about 22 carbon atoms in
the alkyl moiety;
d. alkyl methacrylates having from about 8 to about 22 carbon atoms
in the alkyl moiety;
e. vinyl alkyl ethers having from about 8 to about 22 carbon atoms
in the alkyl moiety; and
f. vinyl esters of aliphatic acids having from about 6 to about 22
carbon atoms in the alkyl moiety;
and mixtures thereof.
4. The process of claim 2 wherein said polar moiety is selected
from the group consisting of:
a. sulfoalkyl acrylates having from 1 to about 4 carbon atoms in
the alkyl moiety thereof;
b. sulfoalkyl methacrylates having from 1 to about 4 carbon atoms
in the alkyl moiety thereof;
c. metal salts of sulfoalkyl acrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof, the metals forming said
salts being selected from the group consisting of metals in Groups
I, IIa, IIb and VIII of the Periodic Chart;
d. metal salts of sulfoalkyl methacrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof, the metals forming said
salts being selected from the group consisting of metals in Groups
I, IIa, IIb and VIII of the Periodic Chart;
e. amine salts of sulfoalkyl acrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof;
f. amine salts of sulfoalkyl methacrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof;
g. metal salts of acids selected from the group consisting of
acrylic and methacrylic acids, the metals forming said metal salts
being selected from the group consisting of metals in Groups I,
IIa, IIb and VIII of the Periodic Chart;
h. amine salts of acids selected from the group consisting of
acrylic and methacrylic acids;
and mixtures thereof.
5. The process of claim 4 wherein the metal is selected from the
group consisting of sodium, lithium, potassium, copper, barium,
zinc, cobalt, iron and magnesium.
6. The process of claim 3 wherein said soluble moiety is selected
from the group consisting of:
a. alkyl styrenes having from about 5 to about 10 carbon atoms in
the alkyl moiety thereof;
b. alkyl acrylates having from about 12 to about 22 carbon atoms in
the alkyl moiety thereof;
c. alkyl methacrylates having from about 12 to about 22 carbon
atoms in the alkyl moiety thereof;
d. vinyl esters of aliphatic acids having from about 10 to about 22
carbon atoms in the alkyl moiety thereof;
and mixtures thereof.
7. The process of claim 2 wherein the polymer contains at least one
substantially insoluble moiety.
8. The process of claim 7 wherein said insoluble moiety is selected
from the group consisting of:
a. a styrene compound selected from the group consisting of
styrene, methyl styrene, methoxy styrene and a halogenated
styrene;
b. alkyl acrylates having from about 1 to about 4 carbon atoms in
the alkyl moiety;
c. alkyl methacrylates having from 1 to about 4 carbon atoms in the
alkyl moiety;
d. vinyl alkyl ethers having from 1 to about 4 carbon atoms in the
alkyl moiety; and
e. vinyl esters of aliphatic acids having from about 1 to about 4
carbon atoms in the alkyl moiety;
and mixtures thereof.
9. The process of claim 8 wherein said insoluble moiety is selected
from the group consisting of:
a. styrene;
b. .alpha.-methyl styrene;
c. alkyl acrylates having from 1 to about 4 carbon atoms in the
alkyl moiety thereof;
d. alkyl methacrylates having from 1 to about 4 carbon atoms in the
alkyl moiety thereof; and
e. vinyl esters of aliphatic acids having from 1 to about 4 carbon
atoms in the alkyl moiety thereof;
and mixtures thereof.
10. The process of claim 9 wherein said polymer contains from about
35 to about 68.5 weight percent of said soluble moiety, from about
30 to about 63.5 weight percent of said insoluble moiety and from
about 1.5 to about 16 weight percent of said polar moiety.
11. The process of developing electrostatic charge patterns carried
on the surface of an electrographic element comprising the steps of
forming said electrostatic charge patterns on said electrographic
element and contacting said charge patterns with a liquid developer
comprising an electrically insulating carrier liquid having a
dielectric constant less than about 3 and a volume resistivity
greater than about 10.sup.10 ohm-cm, said carrier liquid containing
at least a first and second polymer, said first polymer containing
at least three monomeric moieties comprising a polar moiety, a
soluble moiety, and a substantially insoluble moiety as
follows:
a. at least about 1.5 .times. 10.sup.-.sup.4 moles/1 g. of said
first polymer being a polar moiety selected from the group
consisting of:
1. sulfoalkyl acrylates having from 1 to about 4 carbon atoms in
the alkyl moiety thereof;
2. sulfoalkyl methacrylates having from 1 to about 4 carbon atoms
in the alkyl moiety thereof;
3. metal salts of sulfoalkyl acrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof, the metals forming said
salts being selected from the group consisting of metals in Groups
I, IIa, IIb and VIII of the Periodic Chart;
4. metal salts of sulfoalkyl methacrylates having from 1 to about 4
carbon atoms on the alkyl moiety thereof, the metals forming said
salts being selected from the group consisting of metals in Groups
I, IIa, IIb and VIII of the Periodic Chart;
5. amine salts of sulfoalkyl acrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof;
6. amine salts of sulfoalkyl methacrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof;
7. metal salts of acids selected from the group consisting of
acrylic and methacrylic acids, the metals forming said metal salts
being selected from the group consisting of metals in Groups I,
IIa, IIb and VIII of the Periodic Chart; and
8. amine salts of acids selected from the group consisting of
acrylic and methacrylic acids; and mixtures thereof;
b. a sufficient amount of the soluble moiety to yield a
dispersibility ratio for said first polymer in the liquid carrier
greater than about 0.825, the soluble moiety selected from the
group consisting of:
1. alkyl styrenes having from about 5 to about 10 carbon atoms in
the alkyl moiety thereof;
2. alkyl acrylates having from about 12 to about 22 carbon atoms in
the alkyl moiety thereof;
3. alkyl methacrylates having from about 12 to about 22 carbon
atoms in the alkyl moiety thereof; and
4. vinyl esters of aliphatic acids having from about 10 to about 22
carbon atoms in the alkyl moiety thereof; and mixtures thereof;
and
c. the substantially insoluble moiety selected from the group
consisting of:
1. styrene;
2. .alpha.-methyl styrene;
3. alkyl acrylates having from 1 to about 4 carbon atoms in the
alkyl moiety thereof;
4. alkyl methacrylates having from 1 to about 4 carbon atoms in the
alkyl moiety thereof; and
5. vinyl esters of aliphatic acids having from 1 to about 4 carbon
atoms in the alkyl moiety thereof; and mixtures thereof,
and said second polymer containing at least three monomeric
moieties comprising a polar moiety, a soluble moiety, and a
substantially insoluble moiety as follows:
a. from about 0.5 to about 20 weight percent of a polar moiety
selected from the group consisting of:
1. sulfoalkyl acrylates having from 1 to about 4 carbon atoms in
the alkyl moiety;
2. sulfoalkyl methacrylates having from 1 to about 4 carbon atoms
in the alkyl moiety;
3. metal salts of sulfoalkyl acrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof, the metals forming said
salts being selected from the group consisting of metals in Groups
I, IIa, IIb, and VIII of the Periodic Chart;
4. metal salts of sulfoalkyl methacrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof, the metals forming said
salts being selected from the group consisting of metals in Groups
I, IIa, IIb, and VIII of the Periodic Chart;
5. amine salts of sulfoalkyl acrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof;
6. amine salts of sulfoalkyl methacrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof;
7. acids selected from the group consisting of acrylic and
methacrylic acids;
8. metal salts of acids selected from the group consisting of
acrylic and methacrylic acids, the metals forming said metal salts
being selected from the group consisting of metals in Groups I,
IIa, IIb and VIII of the Periodic Chart;
9. amine salts of acids selected from the group consisting of
acrylic and methacrylic acids;
10. aminoalkyl acrylates having from 1 to about 4 carbon atoms in
the alkyl moiety thereof, the amino group being an alkyl-amino
having from 1 to about 4 carbon atoms in the alkyl moiety thereof,
and
11. aminoalkyl methacrylates having from 1 to about 4 carbon atoms
in the alkyl moiety thereof, the amino groups being an alkylamino
having from 1 to about 4 carbon atoms in the alkyl moiety thereof;
and
mixtures thereof; and
b. from about 10 to about 25 weight percent of a moiety soluble in
said carrier liquid and selected from the group consisting of:
1. alkyl styrenes having from about 5 to about 10 carbon atoms in
the alkyl moiety thereof;
2. alkyl acrylates having from about 12 to about 22 carbon atoms in
the alkyl moiety thereof;
3. alkyl methacrylates having from about 12 to about 22 carbon
atoms in the alkyl moiety thereof; and
4. vinyl esters of aliphatic acids having from about 10 to about 22
carbon atoms in the alkyl moiety thereof; and mixtures thereof;
and
c. from about 60 to about 85 weight percent of a moiety
substantially insoluble in said carrier liquid and selected from
the group consisting of:
1. styrene;
2. .alpha.-methyl styrene;
3. alkyl acrylates having from 1 to about 4 carbon atoms in the
alkyl moiety thereof;
4. alkyl methacrylates having from 1 to about 4 carbon atoms in the
alkyl moiety thereof; and
5. vinyl esters of aliphatic acids having from 1 to about 4 carbon
atoms in the alkyl moiety thereof; and mixtures thereof.
12. The process of claim 11 wherein said developer contains a
colorant.
13. The process of claim 12 wherein said polar moiety in said first
polymer is a moiety selected from the group consisting of
sulfoalkyl methacrylates having from 1 to about 4 carbon atoms in
the alkyl moiety thereof, metal salts of sulfoalkyl methacrylates
having from 1 to about 4 carbon atoms in the alkyl moiety thereof,
the metals forming said salts being selected from the group
consisting of metals in Groups I, IIa, IIb and VIII of the Periodic
Chart and metal salts of acrylic acid, the metals forming said
metal salts being selected from the group consisting of metals in
Groups I, IIa, IIb and VIII of the Periodic Chart, the polar moiety
in said second polymer is a moiety selected from the group
consisting of sulfoalkyl methacrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof, metal salts of sulfoalkyl
methacrylates having from 1 to about 4 carbon atoms in the alkyl
moiety thereof, the metals forming said salts being selected from
the group consisting of metals in Groups I, IIa, IIb and VIII of
the Periodic Chart, acrylic acid, metal salts of methacrylic acid,
the metals forming said metal salts being selected from the group
consisting of metals in Groups I, IIa, IIb and VIII of the Periodic
Chart and amino alkyl methacrylates having from 1 to about 4 carbon
atoms in the alkyl moiety thereof, the amino group being an alkyl
amino having from 1 to about 4 carbon atoms in the alkyl moiety
thereof, said soluble moiety in each of said first and said second
polymers is a moiety selected from the group consisting of alkyl
methacrylates having from about 12 to about 18 carbon atoms in the
alkyl moiety and alkyl acrylates having from about 12 to about 18
carbon atoms in the alkyl moiety, and said substantially insoluble
moiety in each of said first and second polymers is a moiety
selected from the group consisting of styrene, an alkyl acrylate
having from 1 to about 4 carbon atoms in the alkyl moiety and an
alkyl methacrylate having from 1 to about 4 carbon atoms in the
alkyl moiety.
14. The process of claim 12 wherein said first polymer contains at
least a polar moiety selected from the group consisting of
sulfoethyl methacrylate and its partial sodium salt, sulfopropyl
methacrylate and ts its sodium salt, the lithium salt of sulfoethyl
methacrylate and the lithium salt of methacrylic acid, a soluble
moiety selected from the group consisting of lauryl methacrylate
and octadecyl methacrylate and a substantially insoluble moiety
selected from styrene, and said second polymer contains at least a
polar moiety selected from the group consisting of sulfoethyl
methacrylate, the lithium salt of sulfoethyl methacrylate,
dimethylaminoethyl methacrylate, acrylic acid, and the barium,
lithium, zinc and cobalt salts of methacrylic acid, a soluble
moiety selected from the group consisting of lauryl methacrylate
and octadecyl methacrylate, and a substantially insoluble moiety
selected from the group consisting of ethyl acrylate, ethyl
methacrylate and butyl methacrylate.
Description
This invention relates to electrography and more particularly to
novel liquid developer compositions and their use in the
development of electrostatic charge patterns.
Electrophotographic imaging processes and techniques are based on
the discovery that certain materials which are normally insulating
become conductive during exposure to electromagnetic radiation of
certain wavelengths after being electrically charged. Such
materials, which may be either organic or inorganic, are termed
photoconductors. They are conveniently formed into useable
image-forming elements by coating a layer of the photoconductive
composition, together with an electrically insulating resinous
binder where necessary or desirable, onto a suitable support. Such
an element will accept and retain an electrostatic charge in the
absence of actinic radiation. In use, the surface of the element is
uniformly charged in the dark, typically by placing it under an ion
source, such as a corona charger, and exposed to an imagewise
pattern of actinic radiation, which selectively reduces the
potential of the surface charge to produce a charge pattern
corresponding to the radiation pattern. The resultant charge
pattern or electrostatic latent image may be developed by
contacting it with suitably charged marking particles which adhere
in accordance with the charge pattern or it may be transferred to
another insulating surface upon which it is developed. The marking
particles can be in the form of a dust, i.e., powder, or a pigment
in a resinous carrier, i.e., toner, as described, for example, in
Giaimo U.S. Pat. No. 2,786,440, dated Mar. 26, 1957. The particles
may be used or fixed to the surface by known means such as heat or
solvent vapor, or they may be transferred to another surface to
which they may similarly be fixed, to produce a permanent
reproduction of the original radiation pattern.
Dry development systems suffer from the disadvantage that
distribution of the powder on the surface of the element is
difficult to control. They can have the further disadvantages that
excessive amounts of dust may be generated and that high resolution
is difficult to attain due to the generally relatively large size
of the powder particles. Many of these disadvantages are avoided by
the use of a liquid developer of the type described, for example,
in Metcalfe et al U.S. Pat. No. 2,907,674, issued Oct. 6, 1959.
Such developers usually comprise an electrically insulating liquid
which serves as a carrier and which contains a dispersion of
charged particles comprising a pigment such as carbon black,
generally associated with a resinous binder such as, for example,
an alkyd resin. A charge control agent is often included in order
to stabilize the magnitude and polarity of the charge on the
dispersed particles. In some cases, the binder itself serves as a
charge control agent.
Many resins used in prior art liquid developers are derived from
naturally occurring fats and oils such as soybean oil, linseed oil,
and the like. As a consequence, such developers may have a highly
variable initial composition. Furthermore, since these natural
products typically contain oxidizable or polymerizable groups,
developer compositions prepared therefrom are subject to
unpredictable change, and the developer is frequently useable for
only a very short period of time after preparation. Replenishment
of such an aged developer gives inconsistent and unreliable
results.
Liquid developers are also frequently used in toner transfer
systems. When so used, they must give consistently high uniform
density not only on the element on which the image is initially
formed but also on the transfer or receiver sheet. Liquid
developers of the prior art, including some made with styrene and
acrylic esters such as alkyl esters of acrylic and methacrylic
acids and their derivatives such as amine derivatives, do not meet
the transfer requirement, as image transfer to the receiver sheet
is typically spotty, nonuniform and subject to variation with
developer age. Developers showing such uncontrollable and
unpredictable variations in developed and transferred density do
not meet the requirements for stability and consistency demanded in
a high volume electrophotographic process.
Accordingly, there is a need in the art for binders for liquid
developer compositions which are chemically well characterized and
which are not subject to aerial oxidation. There is a further need
for liquid developer compositions which can be made reproducibly
and which retain their properties for extended periods after
preparation.
It is, therefore, an object of this invention to provide novel
compositions for the liquid development of electrostatic charge
patterns.
It is another object of this invention to provide new, stable
liquid developer compositions which retain their charge and
dispersion stability for extended periods, and which do not
deteriorate with age or upon exposure to the atmosphere.
It is yet another object of this invention to provide liquid
developer compositions which are readily replenished after becoming
depleted with use.
It is still another object of this invention to provide
reproducible liquid electrophotographic developers containing well
characterized synthetic resin constituents.
It is a further object of this invention to provide a process for
the development of electrostatic charge patterns using the novel
liquid developer compositions of this invention.
These and other objects and advantages are accomplished in
accordance with this invention by the preparation and use of liquid
developer compositions containing certain random copolymers. The
term copolymer as used herein has reference to an addition polymer
containing at least two randomly recurring monomeric units. The
term thus encompasses polymers containing three, four, or
occasionally even more randomly recurring monomeric units. The
copolymers are more particularly characterized in that they contain
as component groups units derived from monomers each of which bears
a predetermined relationship to the carrier liquid with which the
liquid developer is ultimately prepared. At least one of the
monomeric moieties of the copolymer is a polar moiety and at least
one other of the monomeric moieties of the copolymer is a moiety
soluble in the carrier liquid. The soluble moiety is present in an
amount sufficient to yield a dispersibility ratio for the copolymer
in the liquid carrier greater than about 0.825. The polar moiety is
present in an amount of at least about 1.5 .times. 10.sup.-.sup.4
moles/gm. of polymer. The polar moiety is a moiety selected from
the following group:
a. sulfoalkyl acrylates such as compounds having the formula:
##SPC1##
where R is an alkylene group;
b. sulfoalkyl methacrylates such as compounds having the formula:
##SPC2##
where R is an alkylene group;
c. metal salts of sulfoalkyl acrylates such as compounds having the
formula: ##SPC3##
where R is an alkylene group and M.sup..sym. is a metal cation;
d. metal salts of sulfoalkyl methacrylates such as compounds having
the formula: ##SPC4##
where R is an alkylene group and M.sup..sym. is a metallic
cation;
e. amine salts of sulfoalkyl acrylates such as compounds having the
formula: ##SPC5##
where R.sup.1 is an alkylene group and .sup..sym.R.sup.2 is a
cation formed from an amine;
f. amine salts of sulfoalkyl methacrylate such as compounds having
the formula: ##SPC6##
where R is an alkylene group and .sup..sym.R.sup.2 is a cation
formed from an amine;
g. metal salts of acrylic and methacrylic acids such as compounds
having the formula: ##SPC7##
where R.sup.1 is H or methyl and M.sup..sym. is a metallic cation;
and
h. amine salts of acrylic and methacrylic acid such as compounds
having the formula: ##SPC8##
where R.sup.1 is H or methyl and .sup..sym.R.sup.2 is a cation
formed from an amine;
and mixtures thereof.
As used in the present specification the dispersibility ratio of a
particular copolymer in a particular developer carrier liquid is
defined by the following test. A 4.0 gram quantity of copolymer to
be tested is admixed into one liter of a particular developer
carrier liquid using a Waring or Polytron Blender operating within
the range of 10,000 to 18,000 rpm. This mixture is then centrifuged
at 34,000 G forces for about 60 minutes. At the end of this time,
the mixture is analyzed to determine the amount of polymer which
has precipitated. To form the stable developers of the present
invention, it has been determined that useful polymers should be
dispersible to the extent that at least about 3.3 grams of the
original 4.0 gram quantity of polymer remain suspended or dissolved
in the carrier liquid after centrifuging. The dispersibility ratio
is then calculated as the amount of polymer which remains suspended
in the carrier liquid divided by the 4.0 grams of polymer
originally mixed into the carrier liquid. A dispersibility ratio of
0.825 is equivalent to 3.3 divided by 4.0.
As used in the present specifications, "soluble" monomeric moieties
which can be copolymerized with the polar moieties to form the
copolymers used in the liquid developer of the invention are
generally those moieties which, when polymerized, are capable of
forming a homopolymer having an inherent viscosity as hereinafter
defined of from about 0.4 to about 0.5 in chloroform at room
temperature (about 25.degree.C.) and a solubility (at 25.degree.C)
in the carrier liquid to the extent that at least 5 parts by weight
of polymer are soluble in 95 parts by weight of carrier liquid. In
contrast, the term "insoluble" has reference to a monomeric moiety,
a homopolymer of which, under the same conditions, is soluble in
the carrier liquid to the extent of less than about 1 part by
weight of polymer per 99 parts by weight of carrier liquid.
Representative soluble moieties which generally can be
copolymerized with the polar moieties set forth to form the
copolymers used in the liquid developers of the invention may be
selected from the group comprising of:
a. alkyl styrenes such as compounds having the formula ##SPC9##
where R is an alkyl having from about 3 to about 10 carbon atoms in
the alkyl moiety;
b. alkoxy styrenes such as compounds having the formula
##SPC10##
where R is an alkyl having from about 3 to about 10 carbon atoms in
the alkyl moiety, for example, p-amyloxystyrene;
c. alkyl acrylates such as compounds having the formula
##SPC11##
where R is an alkyl having from about 8 to about 22 carbon atoms in
the alkyl moiety;
d. alkyl methacrylates such as compounds having the formula
##SPC12##
where R is an alkyl having from about 8 to about 22 carbon atoms in
the alkyl moiety;
e. vinyl alkyl ethers such as compounds having the formula
CH.sub.2 = CH -- O -- R
where R is an alkyl having from about 8 to about 22 carbon atoms in
the alkyl moiety; and
f. vinyl esters of aliphatic acids such as compounds having the
formula: ##SPC13##
where R is an alkyl having from about 6 to about 22 carbon atoms in
the alkyl moiety;
and mixtures thereof. Other soluble moieties may also be used.
Generally, it has been found that if the soluble moiety is present
in the copolymer to the extent of at least about 35 weight percent
of the polymer, a copolymer is obtained capable of forming a
substantially stable dispersion in a typical carrier liquid.
Generally, the polar moiety is present in an amount not in excess
of about 20 weight percent of the polymer. If no further monomer
moiety is present, then, it is preferred that the soluble moiety be
present to the extent of at least about 84 weight percent of the
polymer.
Preferred polar moieties contained in the copolymers used in the
preparation of the liquid developers of the invention generally
include the following groups:
Group A. sulfoalkyl acrylates and sulfoalkyl methacrylates having
from 1 to about 4 carbon atoms in the alkyl moiety thereof;
Group B. metal salts of sulfoalkyl acrylates and sulfoalkyl
methacrylates having from 1 to about 4 carbon atoms in the alkyl
moiety thereof, the metals forming the metal salts being generally
those from Groups I, IIa, IIb and VIII of the Periodic Chart;
Group C. amine salts of the said sulfoalkyl acrylates and
sulfoalkyl methacrylates; and
Group D. metal salts and amine salts of acrylic and methacrylic
acids, the metals forming the metal salts being generally those
from the above-noted Groups of the Periodic Chart;
and mixtures thereof. Partial metal and amine salts of the esters
and acids can also be used, as can mixtures of the complete or
partial salts with the salt-free form of the esters and acids.
Typical polar groups representative of Groups A-D set forth
hereinabove which can be used in the preparation of the copolymers
comprising the liquid developers of the present invention include
the following:
Group A
sulfoethyl methacrylate
sulfoethyl acrylate
sulfopropyl methacrylate
sulfobutyl methacrylate
Group B
sulfoethyl methacrylate, sodium salt
sulfoethyl methacrylate, partial sodium salt
sulfopropyl methacrylate, sodium salt
sulfobutyl methacrylate, potassium salt
sulfoethyl methacrylate, lithium salt
sulfoethyl methacrylate, copper salt
Group C
sulfopropyl methacrylate, dimethylammonium salt
sulfoethyl methacrylate, diethylammonium salt
sulfomethyl acrylate, dimethylammonium salt
Group D
sodium methacrylate
sodium acrylate
lithium methacrylate
potassium acrylate
barium methacrylate
zinc methacrylate
cobalt methacrylate
ferrous acrylate
magnesium methacrylate
zinc acrylate
and mixtures thereof.
Preferred soluble moieties contained in the copolymers used in the
preparation of the liquid developers of the invention generally
include the following:
a. alkyl styrenes having from about 5 to about 10 carbon atoms in
the alkyl moiety;
b. alkyl acrylates and methacrylates having from about 12 to about
22 carbon atoms in the alkyl moiety; and
c. vinyl esters of aliphatic acids having from about 10 to about 22
carbon atoms in the alkyl moiety;
and mixtures thereof. Typical soluble moieties or groups which can
be so used include the following:
4-pentyl styrene
4-hexyl styrene
4-octyl styrene
lauryl acrylate
hexadecyl methacrylate
octadecyl methacrylate
eicosyl acrylate
docosyl methacrylate
vinyl caprate
vinyl laurate
vinyl palmitate
vinyl stearate
vinyl eicosate
vinyl docosate
and mixtures thereof.
The term "inherent viscosity," as used herein, is defined by the
following formula:
.nu. .sub.I = 1n .nu. solution/.nu. solvent / C
wherein .nu. solution is the viscosity of the solution, .nu.
solvent is the viscosity of the solvent and C is the concentration
in grams per 100 ml. of the polymer solvent. The determination is
made at a concentration of 0.25.degree. grams of polymer in 100 ml.
of chloroform at a temperature of 25.degree.C.
Preferred copolymers used in the preparation of the liquid
developers of the invention also contain at least one insoluble
moiety or group copolymerized with the aforementioned polar and
soluble moieties. Representative insoluble moieties which may be
suitable for being so copolymerized include the following:
a. styrenes selected from the group of styrene, methyl styrene,
methoxy styrene and a halogenated styrene;
b. alkyl acrylates having from about 1 to about 4 carbon atoms in
the alkyl moiety;
c. alkyl methacrylates having from 1 to about 4 carbon atoms in the
alkyl moiety;
d. vinyl alkyl ethers having from 1 to about 4 carbon atoms in the
alkyl moiety; and
e. vinyl esters of aliphatic acids having from about 1 to about 4
carbon atoms in the alkyl moiety;
and mixtures thereof.
Preferred insoluble moieties contained in the copolymers used in
the preparation of the subject liquid developers generally include
the following:
a. styrene and methyl styrene;
b. alkyl acrylates having from 1 to about 4 carbon atoms in the
alkyl moiety;
c. alkyl methacrylates having from 1 to about 4 carbon atoms in the
alkyl moiety; and
d. vinyl esters of aliphatic acids having from 1 to about 4 carbon
atoms in the alkyl moiety;
and mixtures thereof. Typical insoluble moieties or groups which
can be so used include the following:
styrene
.alpha.-methyl styrene
ethyl acrylate
methyl acrylate
butyl acrylate
ethyl methacrylate
propyl methacrylate
butyl methacrylate
vinyl acetate
vinyl propionate
vinyl butyrate
and mixtures thereof.
It will be apparent that the choice of particular soluble,
insoluble and polar monomeric moieties is determined by a number of
factors. The degree of solubility in the carrier liquid may be
controlled by proper adjustment of the ratio of soluble moiety to
insoluble moiety. In addition, the nature of the particular soluble
monomeric moiety, such as the degree of solubility of a homopolymer
comprising it, will influence the particular insoluble monomeric
moiety chosen to copolymerize with it to give the final polymer.
For example, if the soluble monomer is one having a relatively long
alkyl group attached to it, rendering a polymer containing it
relatively soluble, the insoluble monomer is desirably one having a
relatively short alkyl group attached to it, to balance the
properties. On the other hand, a relatively short alkyl group on
the soluble monomer in general requires a somewhat longer alkyl
group on the insoluble monomer. Generally, as indicated above,
useful polymers of the present invention are dispersible in the
carrier liquid to the extent that if a 4.0 gram quantity of polymer
is added to one liter of carrier, at least about 3.3 grams will
remain dispersed therein after centrifuging the mixture at 34,000 G
forces for about 60 minutes.
In general, the polymers comprising the liquid developers of the
invention are prepared by an addition polymerization reaction
wherein all of the component monomers are combined in a reaction
vessel in a reaction medium, such as dioxane, and a suitable free
radical initiator. The vessel containing the solution is then
flushed with an inert gas, such as nitrogen, and heated to a
temperature sufficient for the polymerization reaction to proceed
at a reasonable rate. The temperature, in general, is above room
temperature and preferably about 40.degree. to 80.degree.C. After
the polymer has formed, it is removed from the reaction mixture and
purified as necessary. Polymers produced according to this
procedure typically have an inherent viscosity, as hereinbefore
defined and measured, in the range of from about 0.1 to about 0.8.
The resultant polymers contain recurring units of one or more
moieties derived from soluble monomers, one or more moieties
derived from insoluble monomers, and one or more moieties derived
from polar monomers. In general, a typical polymer used in the
liquid developers of the invention contains from about 35 to about
70 weight percent of soluble moieties, from about 30 to about 65
weight percent of insoluble moieties and from about 1.5 to about 20
weight percent of polar moieties. Preferred polymers of the
invention contain from about 40-55 weight percent soluble moiety,
from about 35-55 weight percent of insoluble moiety and from 1.5-16
percent polar moiety. The dispersibility of the polymer can be
adjusted as desired by proper balancing of the relative abundance
of the soluble and insoluble moieties. The relative amount of polar
moiety can be varied to provide polymers having different charge
properties when incorporated into a liquid developer. Mechanical
properties such as abrasion resistance, and fixability of the
resultant toner image can also be adjusted at will by properly
balancing the ratio of the components in the polymer.
It should be noted that the relative abundance of the various
starting monomers in the polymerization medium is not always
indicative of the percentage composition to be expected in the
resultant polymer. When acrylic monomers are used as starting
materials, for example, it is found that the composition of the
polymer bears a very close correlation to the relative abundance in
the starting solution, whereas when styrenes are used as starting
materials, the correlation is not so close. Such deviations are
well known to the polymer chemist, and one skilled in the art
should readily be able to produce such variations in composition as
may be desired to meet particular requirements.
As has been mentioned, a wide variety of salts of the polymers can
be used. Useful salts include those of metals chosen from Groups I,
IIa, IIb and VIII of the Periodic Chart of the Elements (see, for
example Handbook of Chemistry and Physics, 51st Edition, 1970-1971,
p. B-3). Preferred salts are those of lithium, sodium, potassium,
copper, magnesium, barium, calcium, zinc, cadmium, iron and cobalt,
with those of lithium, sodium, potassium, copper, barium, zinc and
cobalt being particularly preferred. The salts may be complete or
partial salts of the polymer, and may be made by any of several
procedures. As an example, a polymer containing the desired
moieties may be made first and converted to the salt form by mixing
with a suitable metal compound in the proper reaction medium.
Useful compounds for this purpose are, for example, the hydroxides
or carbonates of the metal. Alternatively, the appropriate monomer
may be converted to the salt form before polymerization, by
treating it with a base or basic salt of the metal, followed by
polymerization of the salt form into the desired polymer. Partial
salts can also be formed by using as starting materials a blend of
converted and unconverted monomers in the polymerization medium.
The proportion of the salt form present is determined by the
relative quantities of the two forms present when polymerization is
initiated.
Liquid developers containing the novel polymers described herein
typically comprise a dispersion of the polymer in a suitable
carrier liquid. A common method of preparing such a dispersion is
solvent milling. A quantity of the polymer is dissolved in a
suitable solvent and the solution placed in a ball mill. Pigments
and other additives which may be necessary or desirable are added
to the mix and the whole milled for a suitable time, typically up
to a week. Alternatively, a viscous solution of the polymer is
placed on compounding rolls having chilled (5.degree. to
10.degree.C.) water passing through the cooling system. Pigments
and other additives are then placed on the rolls and thoroughly
mixed and blended with the polymer. The pigment is generally
present in an amount of from about 200 to about 10 percent of the
weight of the resin. After passing the complete mix through the
mill several times to completely blend the ingredients, the mix is
removed.
Liquid developers are made from the toner concentrate formed as
above by dispersing the concentrate in a suitable electrically
insulating carrier liquid. Carrier liquids which may be used to
form such developers can be selected from a wide variety of
materials. Preferably, the liquid has a low di-electric constant
and a very high electrical resistance such that it will not disturb
or destroy the electrostatic charge pattern being developed. In
general, useful carrier liquids should have a dielectric constant
of less than about 3, should have a volume resistivity greater than
about 10.sup.10 ohm-cm and should be stable under a variety of
conditions. Suitable carrier liquids include halogenated
hydrocarbon solvents, for example, fluorinated lower alkanes, such
as trichloromonofluoromethane, trichlorotrifluoroethane, etc.,
having a boiling range typically from about 2.degree.C. to about
55.degree.C. Other hydrocarbon solvents are useful, such as
isoparaffinic hydrocarbons having a boiling range of from about
145.degree.C. to about 185.degree.C., such as Isopar G (Humble Oil
and Refining Co.) or cyclohydrocarbons such as cyclohexane.
Additional carrier liquids which may be useful in certain
situations include polysiloxanes, odorless mineral spirits, octane,
etc.
Although it is possible to use the resinous copolymers to prepare
liquid developers without further addenda, as in situations in
which a colorless image is desired, it is customary to add a
colorant to give the image optical density. Useful colorants can be
selected from a variety of materials such as dyestuffs or pigments.
Virtually any of the compounds mentioned in the Color Index, Second
Edition, 1956, Vols. I and II, may, in principle, be used. Included
among the vast number of useful colorants would be such materials
as Hansa Yellow G (C.I. 11680), Nigrosine Spirit soluble (C.I.
50415), Chromogen Black ETOO (C.I. 14645), Rhodamine B (C.I.
45170), Solvent Black 3 (C.I. 26150), Fuchsine N (C.I. 42510), C.I.
Basic Blue 9 (C.I. 52015), etc. Another useful class of colorants
is comprised of nigrosine salts of mono- and difunctional organic
acids having from about 2 to about 20 carbon atoms such as
chloroacetic acid, stearic acid, sebacic acid, lauric acid, azelaic
acid, adipic acid, abietic acid and the like. Nigrosine salts of
this type are disclosed in copending application of Olson, U.S.
Ser. No. 770,122, filed Oct. 23, 1968, entitled UNIFORM POLARITY
RESIN ELECTROSTATIC TONERS.
Other colorants suitable for use in preparing liquid developers
from the polymers described herein include salts of water-soluble
acid dyes, more particularly the metal, alkali metal and ammonium
salts of dyes having sulfonic and/or carboxylic acid groups
contained thereon. Exemplary of these are the lead salt of copper
phthalocyanine tetrasulfonic acid and the magnesium salt of
1-(p-sulfophenyl-3-phenyl)-4-(2,5-dichloro-4-sulfophenylazo)-5-pyrazolone.
These colorants are more particularly described in copending
application of Chechak, U.S. Ser. No. 864,299, filed Oct. 3, 1969,
entitled LIQUID DEVELOPER AND METHOD. Particularly useful colorants
are pigments prepared from the reaction of a strongly acid dye with
a strongly basic dye to form a highly insoluble precipitate having
essentially no color dilution. These pigments and their method of
preparation are more fully disclosed in copending application of
Chechak, U.S. Ser. No. 58,190, filed July 24, 1970, entitled NOVEL
PIGMENTS AND THEIR PREPARATION AND USE.
As has been indicated, the polymers described herein are very
useful for preparing liquid developers which are stable and which
produce permanent images of high quality. However, under certain
image-forming conditions, improved results may be obtained when at
least one additional polymer is added to the composition forming a
liquid developer. The use of two or more copolymers in this way
permits much greater flexibility in the formulation of developers
designed especially for toner transfer, for example. Thus, it is
found that preparation of liquid developers having the capability
of producing an image which cleanly transfers to a receiver sheet
to form thereon an image having high uniform density free from
background, and which developer is at the same time readily
replenishable, is greatly facilitated by the use therein of two or
more polymers of the general type herein disclosed. At least one of
these polymers (Type A) is of the type and has a composition as
already described in detail, while at least one other of these
polymers (Type B) may be of the type hereinafter more particularly
set forth. The Type B polymer is a copolymer containing at least an
insoluble moiety, as hereinbefore defined, which is present in an
amount of at least about 55 weight percent of the polymer, and a
polar moiety which is present in an amount within the range of 0.5
to 20 weight percent of the polymer. The polar moiety is selected
from the group comprising:
a. sulfoalkyl acrylates;
b. sulfoalkyl methacrylates;
c. metal salts of sulfoalkyl acrylates;
d. metal salts of sulfoalkyl methacrylates;
e. amine salts of sulfoalkyl acrylates;
f. amine salts of sulfoalkyl methacrylates;
g. metal salts of acrylic and methacrylic acids;
h. amine salts of acrylic and methacrylic acids;
i. acrylic and methacrylic acids;
j. amino substituted alkyl methacrylates and acrylates such as
compounds having the formula ##SPC14##
where R.sup.1 is H or methyl, R is an alkylene, and R.sup.2 is H or
alkyl, and mixtures thereof.
Insoluble moieties which can be copolymerized with the polar moiety
or moieties are generally those from the same group indicated
hereinbefore with reference to the Type A copolymer. Although it
has been indicated that the amount of insoluble monomer is at least
about 55 weight percent of the Type B polymer, best results are
obtained if the polar moiety is present in an amount of not in
excess of about 16 weight percent of the polymer. Thus, if no
further monomeric moiety is present, it is preferred that the
insoluble moiety be present to the extent of at least about 84
weight percent of the polymer.
Preferred polar moieties contained in said Type B polymer generally
include the following:
A. sulfoalkyl acrylates and sulfoalkyl methacrylates having from 1
to about 4 carbon atoms in the alkyl moiety thereof;
B. metal salts of sulfoalkyl acrylates and sulfoalkyl methacrylates
having from 1 to about 4 carbon atoms in the alkyl moiety thereof,
the metals forming the metal salts being generally those from
Groups I, IIa, IIb and VIII of the Periodic Chart;
C. amine salts of the said sulfoalkyl acrylates and sulfoalkyl
methacrylates, including substituted amine salts;
D. metal salts and amine salts of acrylic and methacrylic acids,
the metals forming the metal salts being generally those from the
above-noted Groups of the Periodic Chart;
E. aminoalkyl methacrylates and acrylates having from 1 to about 4
carbon atoms in the alkyl moiety thereof, preferred amino groups
including an alkylamino group having from 1 to about 4 carbon atoms
in the alkyl moiety thereof including a dialkylamino group;
F. acrylic and methacrylic acids;
and mixtures thereof. The polar group of the Type B polymer can
also comprise partial metal salts and partial amine salts of the
esters and acids and mixtures thereof with each other and with free
form of the esters and acids. Typical polar groups which can be
used include all those set forth as suitable for the Type A polymer
and, in addition, groups such as those set forth hereinafter:
acrylic acid
methacrylic acid
diethylaminoethyl methacrylate
dimethylaminoethyl methacrylate
ethylpropylaminoethyl acrylate
dibutylaminoethyl methacrylate
diethylaminobutyl acrylate
dibutylaminoethyl acrylate
Preferred copolymers used as the Type B polymer in the liquid
developers of the invention also contain at least one soluble
moiety or group copolymerized with the aforementioned polar and
insoluble moieties. Suitable soluble moieties are selected from the
group generally as those which are suitable for incorporation in
the Type A copolymer. When a copolymer containing at least three
monomeric moieties of the types described is prepared for use as
the Type B polymer, it is preferred that the polar moiety be
present in an amount of from about 0.5 to about 16 weight percent,
the insoluble moiety be present in an amount of from about 60 to 85
weight percent, and the soluble moiety be present in an amount of
from about 10 to about 25 weight percent. If more than three
distinct monomeric entities are included in the polymer, the above
weight composition applies generally to the type of moiety involved
and not necessarily to the presence of a distinct chemical species.
As is evident, wide variations in composition within these broad
ranges may be made to adapt developer compositions to meet the
requirements of particular situations.
A number of advantages are realized through the use of two or more
polymers of the type described in the liquid developer compositions
of the invention. These advantages relate to density control,
transfer characteristics and replenishment. These three properties
are particularly important in those situations in which the
developers are to be used in preparing images in a three-color
transfer process.
Density control refers to a property desirable in multicolor
reproduction processes in which separate color images are
superimposed to produce a copy of an original. In such processes
each transferred image to be superposed should bear a predetermined
tonal relationship to the original from which it is derived. To a
certain extent, the tonal relationships can be controlled by
electrical parameters, such as the relationship connecting surface
potential of the photoconductive element used to produce the image
and the exposure received by the element, that is, the "electrical
H and D" curve. The translation of this electrical curve into the
corresponding visual curve, however, is controlled predominantly by
the charge characteristics of the toner particles. Developers in
which density is not sensitive to changes in binder-to-pigment
ratio or to changes in polar group concentration are considered,
for purposes of this invention, to have poor density control, while
developers in which density is quite sensitive to these parameters
are considered to have good density control.
Another aspect of the preparation of multiple-use developers
involves their transfer characteristics. In transfer processes such
as the above, it is desirable that each colored image transfer
substantially completely, thereby duplicating consistently on the
receiver member the tonal scale that is developed on the
photoconductive element. Developers that give images which transfer
completely and therefore duplicate the developed tone scale are
considered, for purposes of this invention, to have good transfer
characteristics. Developers which give images which transfer only
partially or which do not duplicate the tone scale on the element
are considered to have poor transfer characteristics.
A further aspect of the preparation of developers for multiple use
involves replenishment. In such processes, it is desirable that the
composition of the developer remain essentially constant with use
and that thee reproduction quality of many successive transferred
images is not affected by such use. To prevent change in transfer
reproduction characteristics, the developer components removed must
be replenished at regular intervals. If the various components,
such as binder, pigment, etc., deposit on the image in such
proportions that they can be satisfactorily replenished in the
remaining developer, the developer is considered to have good
replenishment characteristics for the purposes of this invention.
If, however, they deposit on the image in such proportions that
they cannot be replenished totally, the developer is considered to
have poor replenishment characteristics.
Developers containing a mixture of at least two polymers of the
types herein described are found to have unexpectedly enhanced
characteristics. The resultant developers are stable and well
dispersed, have excellent replenishment characteristics, produce
images having excellent density control, and yield complete and
uniform transfer. The advantage of such a mixed polymer developer
over a developer containing only a Type A polymer relates
principally to the transfer and replenishment aspects of multiple
use. A mixed polymer developer shows greatly improved performance
in these respects over a developer containing only a Type A
polymer. A developer containing only a Type B polymer, on the other
hand, either will not disperse or has poor replenishment
characteristics and yields images having poor density control. Both
types of single-polymer developers yield images which do not
transfer cleanly and completely; however, this is not a problem in
those situations where transfer is not necessary. In such
situations, that is, in cases in which the toner image is produced
directly on the element which will bear the final image, uniform
and complete transfer is obviously not a requirement to be met.
Polymers of the two types described hereinbefore may be combined
over a wide range of weight ratios. In general, the weight ratio of
the two polymers is determined by several factors including the
optical density desired or the quantity of polymer to be deposited
for a given charge level, the physical and transfer properties of
the image and developer stability. Charge per particle is, in
general, controlled by the total quantity of polar groups present
in both polymers. The less polar group present, the higher the
density or quantity of polymer deposited per given charge level. If
high densities are desired, it is generally desirable to use
polymers with a relatively small number of polar groups; or, if one
of the polymers utilized contains a relatively high level of polar
groups, then the other polymer(s) should contain a low level of
polar groups. In the case where low densities are desired, it is
usually desirable to use a relatively high level of polar groups in
both polymers; or, if the level of polar groups in one of the
polymers utilized is relatively low, then the level of polar groups
in the other polymer(s) should be relatively high. Similarly, the
relative abundance of soluble and insoluble moieties contained in
the Type A and Type B polymers can be varied to obtain the optimum
balance between the various properties desired. Generally, the
weight ratio of Type B polymer to Type A polymer may be varied
between 0.1 to 3, preferably between 0.25 to 1.5. If a pigment is
used, in general, the Type B polymer is present in an amount of
from about 0.2 to about 2.5 times the weight of the pigment, with
from about 0.5 to 2.0 being preferred. The Type A polymer may be
present in an amount of from about 0.1 to about 5.0 times the
weight of the pigment, with from about 0.3 to about 2.5 being
preferred.
Developer concentrates containing two or more polymers of the types
described herein are usually prepared by initially dissolving the
Type B polymer in a suitable solvent and milling the solution with
the pigment for a suitable period of time. Alternatively, however,
developers can be prepared by milling the pigment into the Type A
polymer and later adding a solution of the Type B polymer, or the
pigments can be milled in mixtures of two or more polymers. In the
case where no pigment is used, Type A and Type B polymers are
usually dissolved separately, combined in the desired proportions
and then dispersed in the carrier liquid. The time is determined by
the amount of milling required to reduce the pigment particle size
to less than one micron, preferably 0.1 to 0.2 micron. Typical
times range up to ten days. A predetermined portion of the
dispersion thus obtained is combined with a solution of the Type A
polymer, and the mixed resin dispersion mixed or milled for a
period of time ranging typically from one-half hour to an hour to
ensure complete and uniform blending. Alternatively, in the case of
both pigmented and unpigmented concentrates, it is sometimes
preferable to dilute the concentrates with approximately an equal
volume of carrier liquid before dispersion of the concentrates in
the liquid carrier to form the working developer.
Because the developers of this invention have a unique combination
of charge and solubility properties, they generally do not require
addition of compounds such as cobalt naphthenate and the like to
supplement the charge conferred by the polymers themselves. In
general, a single polymer of the type described herein or at least
a mixture of that polymer with another provides adequate charge and
stability.
The amount of polymer used in the developer of the present
invention may vary within a fairly wide range. Typically, there is
present an amount of polymer within the range of from about 0.01 to
about 15 percent by weight of the total developer composition. The
carrier liquid represents the bulk of the developer; typically from
about 85 to about 99 percent by weight of the developer comprises
the carrier liquid, typically 93 to about 99 percent of developer
comprises the carrier liquid.
The following examples are included for a further understanding of
the invention:
EXAMPLE 1
Preparation of Poly(styrene-co-lauryl methacrylate-co-2-sulfoethyl
methacrylate)
The following materials are dissolved in 25 ml of 1,4-dioxane:
Styrene 25 g. Lauryl methacrylate 23 g. 2-Sulfoethyl methacrylate 2
g. Azoisobutyronitrile 0.4 g.
The solution is flushed with nitrogen and heated at 60.degree.C.
for 24 hours. The polymer is precipitated by pouring the mixture
into water. The liquid is decanted from the soft product, and the
polymer washed by allowing it to stand in fresh water for several
hours. The water is poured off, and the product dried in vacuum at
40.degree.C. There is obtained a 45 gram quantity of product having
an inherent viscosity in chloroform of 0.32.
EXAMPLE 2
Preparation of Poly(styrene-co-lauryl methacrylate-co-sodium
acrylate)
The procedure of Example 1 is followed with the exception that 4
grams of acrylic acid is substituted for the sulfoethyl
methacrylate in the first step. After washing and drying, there
results 45 g. of the free acid form of the polymer, which has an
inherent viscosity of 0.29. A 10.5 g. portion of this polymer,
dissolved in 200 ml of chloroform, is shaken well with 0.48 g. of
sodium carbonate dissolved in 25 ml of water, forming an emulsion.
Stirring the mixture into isopropanol precipitates the sodium salt
form of the polymer. It is washed in water and vacuum dried as in
Example 1.
EXAMPLE 3
Preparation of Poly(styrene-co-lauryl methacrylate-co-3-sulfopropyl
methacrylate, sodium salt)
A one-liter polymerization flask fitted with a mechanical stirrer
and a nitrogen inlet tube is charged with 125 g. of styrene, 115 g.
of lauryl methacrylate, 10 g. of methacrylic acid, 125 g. of
1,4-dioxane and 1.25 g. of 2,2'-azo-bis(2-methylpropionitrile).
Nitrogen gas is bubbled through the mixture for several minutes,
then the mixture is heated with stirring for 16 hours at
70.degree.C. To the clear, colorless dope resulting is added 50 ml
of a 16 weight percent aqueous sodium hydroxide solution, while
stirring is continued at 75.degree.C for 10 minutes. To the
solution containing poly(styrene-lauryl methacrylate-methacrylic
acid, sodium salt) is then added 20 ml. of 1,3-propane sultone with
stirring at 75.degree.C. for 1 hour. To the thickened dope is added
125 ml of 1,4-dioxane, and stirring continued at a temperature of
80.degree.C. The white emulsified dope is poured into 3 l. of hot
tap water. The polymerization flask is then rinsed with 125 ml. of
dioxane, which is poured into the water. The polymer is kneaded,
the water drained, the polymer kneaded again in hot tap water,
separated, kneaded twice in cold tap water, separated and dried for
16 hours at 80.degree.C. under vacuum. There results a 245.5 g.
yield of white solid having an inherent viscosity of 0.28.
Alternatively, the sodium salt form of the polymer may be prepared
by first forming the monomeric sodium sulfopropyl methacrylate and
substituting it for the methacrylic acid in the starting
solution.
EXAMPLE 4
A developer concentrate is prepared by milling in a ball mill a 1
g. portion of the sodium salt of poly(styrene-co-lauryl
methacrylate-co-3-sulfopropyl methacrylate), 46:50:4 by weight,
with 0.5 g. each of Rhodamine Y (C.I. 45160) and Permanent Cerise T
(C.I. 45160) in 30 ml of Solvesso 100. Solvesso 100 is a
cyclohydrocarbon having a major armoatic component and having a
boiling range of from about 150.degree. to about 185.degree.C, sold
by Humble Oil and Refining Co. A 6 ml portion of the concentrate is
added dropwise to 244 ml of Isopar G under conditions of high
shear. The resultant developer is stable and does not settle upon
storage on the shelf for a period of 180 days. When used to develop
a negatively charged image on a photoconductive element comprising
an organic photoconductor-containing layer carried by a conductive
support, the developer produces a good reproduction of the image,
having a maximum density of 1.5. A similar developer prepared from
a polymer containing dimethylaminoethyl methacrylate in place of
the 3-sulfopropyl methacrylate sodium salt does not give the same
high density and settles upon standing in a much shorter period of
time.
EXAMPLE 5
A developer concentrate is prepared by milling 1 g. of
poly(styrene-co-lauryl methacrylate-co-sulfoethyl methacrylate),
46:50:4 by weight, with 0.5 g. of each of the dyes of Example 4 in
15 ml of Solvesso 100. After 2 days milling, an additional 15 ml of
Solvesso 100 are added. A developer is prepared as in Example 4,
adding 12 ml of the concentrate to 492 ml of Isopar G. The
stability of the developer is comparable to that of the developer
of Example 4. When used to develop an electrostatic charge pattern
as in Example 4, the developer gives a faithful reproduction and
high density.
EXAMPLE 6
A developer concentrate is prepared by milling together 1 g. of the
sodium salt of poly(styrene-co-lauryl methacrylate-co-acrylic
acid), 50:46:4 by weight, with 0.5 g. of each of the colorants of
Example 4, in 15 ml of Solvesso 100, as in the previous Examples.
After two days of milling, 2 g. of additional polymer and 30 ml of
Solvesso 100 are added to produce a concentrate having a
binder:pigment ratio of 3:1. A developer is formed by adding
dropwise 10.5 ml of the concentrate to 240 ml of Isopar G in a high
speed blender which produces high shear, as previously. There
results a stable, positively charged developer having particles in
the range under 1 to 2 microns in size. When used to produce an
image on a charged organic photoconductive element as in the
previous Examples, the developer yields an image having high
contrast and having a density to green light of in excess of 2.0. A
developer prepared in the identical manner which uses, instead, as
the polymer, poly(styrene-co-lauryl methacrylate-co-acrylic acid),
as taught by the prior art, is not stable, as the pigments will not
disperse in the carrier liquid.
EXAMPLE 6A
A developer is prepared as in Example 6 except the lithium salt of
poly(styrene-co-lauryl methacrylate-co-methacrylic acid) 50:46:4 is
used. This developer performs in the same manner as the developer
described in Example 6.
EXAMPLE 6B
A developer is prepared as in Example 6A except the concentrate is
milled in 20 ml. of Isopar G. This developer performs in the same
manner as the developer described in Example 6.
EXAMPLE 7
A developer concentrate is prepared by milling together 1 g. of
copper phthalocyanine pigment (Monastral Fast Blue B, C.I. 74160,
Imperial Chemical Industries, Ltd.) and 1 g. of poly(butyl
methacrylate-co-lauryl methacrylate-co-2-sulfoethyl methacrylate),
40:50:10 by weight, in 20 ml of Solvesso 100. A developer is
prepared by dispersing 3.2 g. of the concentrate in 330 ml of
Isopar G in the manner previously described. There results a very
stable developer which yields images of high density on a
charge-bearing organic photoconductive element. Similar results are
obtained by using as the starting monomers ethyl methacrylate and
octadecyl methacrylate in place of the butyl methacrylate and
lauryl methacrylate, respectively.
EXAMPLE 8
A developer concentrate is prepared by milling together 1 g. of the
sodium salt of poly(styrene-co-lauryl methacrylate-co-methacrylic
acid, 46:50:4 by weight and 1 g. of the diazo dye Permanent Yellow
HR (C.I. Pigment Yellow 83, Farbwerke Hoechst, AG) in 20 ml of
Solvesso 100. A 3.4 ml portion of the concentrate is added to 3.4
ml of Isopar G, shaken for one minute, and the combination added to
326 ml of Isopar G under conditions of high shear. There results a
very stable developer having positive charge with which an
electrostatic charge pattern on an organic photoconductive element
is developed. The developed image has a maximum density of 2.0. No
settling of the developer occurs within six days after preparation.
A developer made from a concentrate similarly prepared with the
exception that the polymer contains the free acid instead of the
sodium salt is also used to develop a charge pattern as above. When
used immediately, the developer gives an equivalent maximum
density; however, dispersion stability is poor, as the developer
settles virtually completely within 24 hours.
EXAMPLE 9
Concentrate 9 is prepared by milling in a ball mill a 1 g. portion
of poly(butyl methacrylate-co-lauryl methacrylate-co-2-sulfoethyl
methacrylate, 77:15:8 by weight, 20 ml. of Solvesso 100, and 1 g.
of red pigment, the 50:50 phosphotungstic; phosphomolybdic acid
salt of C.I. 48070 red dye. Solution 9 is prepared by dissolving 1
g. of poly(styrene-co-lauryl methacrylate-co-2-sulfoethyl
methacrylate), 38:52:10 by weight, in 20 ml. of Solvesso 100. A
liquid developer is made by combining 3.2 g. of Concentrate 9 with
3.4 ml. of Solution 9 using gentle agitation, and adding the
mixture dropwise to 326 ml. of Isopar G in a high speed blender. A
second liquid developer is made in the same manner, except that the
amount of Solution 9 is one-half of that used above. Two identical
organic photoconductive compositions are treated as follows: Each
is given a uniform positive charge and exposed through a negative
original to produce an electrostatic charge pattern of positive
polarity such that the unexposed areas have a maximum positive
polarity and the exposed areas have a differential positive charge
proportional to the exposure. When the two developers made, as
described above, are flowed over the respective surfaces of these
two photoconductive compositions bearing these charge patterns in
the presence of a facing electrode having a positive charge
slightly lower than the maximum charge on the organic
photoconductor, positive images are produced from negative
originals. The density of the images obtained may be varied to an
extent by varying the level of charge on the organic photoconductor
and facing electrode and by varying the exposure level. Both
developed images transfer cleanly to a paper receiving sheet by the
application of an electrostatic charge to the rear surface of the
paper. The transferred images are clean, free from smudging and of
high, uniform density. A developer prepared as above except that
Solution 9 and its dissolved resin are omitted agglomerates
immediately upon addition of the Isopar G, and no image can be
formed therefrom. If concentrate 9 is instead prepared with the
second named resin above and a solution containing the first resin
only is not added, an image is formed, but it does not transfer
cleanly to the receiver sheet. A developer prepared as first set
forth but with the order of addition of the resins reversed also
produces a stable developer which transfers cleanly and
completely.
EXAMPLE 10
Concentrate 10 is preparesd as set forth in Example 9 except that
the polymer is a 1 g. portion of poly(butyl methacrylate-co-lauryl
methacrylate-co-2-sulfoethyl methacrylate), 77:15:8 by weight, the
pigment is copper phthalocyanine tetrasulfonate, cadmium salt, and
the solvent is 20 ml of Solvesso 100. Solution 10 is prepared by
dissolving 1 g. of the sodium salt of poly(styrene-co-lauryl
methacrylate-co-3-sulfopropyl methacrylate), 47:43:10 by weight, in
20 ml. of Solvesso 100. A 3.2 g. portion of Concentrate 10 and a
3.4 ml. portion of Solution 10 are gently mixed together and added
dropwise to 3.4 ml. of Isopar G, to produce a liquid developer. A
second liquid developer is made in the same manner, except that the
amount of Solution 10 is one-half of that set forth above. When
used to develop an electrostatic charge pattern as in Example 9, a
dense blue image is obtained, which transfers completely and
uniformly to a transfer sheet. A developer prepared by omitting
Solution 10 from the mixture agglomerates upon addition of the
Isopar.
EXAMPLE 11
A 1 g. portion of poly(butyl methacrylate-co-lauryl
methacrylate-co-sulfoethyl methacrylate), 80:16:4 by weight, is
dissolved in 20 ml of Solvesso 100, and 0.25 g. of copper acetate
added to the mill and the whole milled for 8 hours to convert the
polymer to the copper salt. A 1 g. portion of the pigment of
Example 9 is next added to the mill, and milling continued for 64
hours. A 3.2 g. portion of Concentrate 11 thus formed is mixed with
3.4 ml. of Solution 10 of Example 10 using gentle agitation, and
the combination added dropwise to 326 ml of Isopar G to form a
liquid developer. An electrostatic charge pattern developed with
this developer yields a high density image having good density
control. The image transfers uniformly and completely to a transfer
sheet when transfer is carried out as in the previous Examples.
EXAMPLE 12
Concentrate 12 is prepared by milling in a ball mill a 1 g. portion
of poly(butyl methacrylate-co-ethyl methacrylate-co-lauryl
methacrylate-co-2-sulfoethyl methacrylate), 26:50:16:8 by weight,
20 ml. of Solvesso 100, and 1 g. of the pigment of Example 7.
Solution 12 is prepared by dissolving 0.5 g. of
poly(styrene-co-lauryl methacrylate-co-2-sulfoethyl methacrylate),
38:52:10 by weight, in 20 ml. of Solvesso 100, and adding thereto
0.5 g. of its partial sodium salt. A liquid developer is made by
gently mixing together a 3.2 g. portion of Concentrate 12 and a 3.4
ml. portion of Solution 12, and adding the mixture dropwise under
shearing conditions to 326 ml. of Isopar G. When used to develop an
electrostatic charge pattern as in the previous Examples, the
developer produces a very high density image which transfers
uniformly and completely to a paper receiver sheet. A developer
made using the resin of Concentrate 12 alone without the resin of
Solution 12 agglomerates promptly upon preparation.
EXAMPLE 13
Concentrate 13 is prepared by milling together in a ball mill a 1
g. portion of poly(ethyl methacrylate-co-lauryl
methacrylate-co-2-sulfoethyl methacrylate), 76:16:8 by weight, 1 g.
of the pigment of Example 7 and 20 ml. of Solvesso 100. Solution 13
is prepared by dissolving 0.5 g. of poly(styrene-co-lauryl
methacrylate-co-2-sulfoethyl methacrylate) and 0.5 g. of its
partial sodium salt, both 46:46:8 by weight, in 20 ml. of Solvesso
100. A liquid developer is made by combining 3.2 g. of Concentrate
13 with 6.8 ml. of Solution 13, and adding the mixture to 323 ml of
Isopar G dropwise, under conditions of high shear. When used to
develop an electrostatic charge pattern, the developer produces a
high density image which transfers well to a paper receiving sheet.
The developer has excellent replenishment characteristics. If the
resin of Concentrate 13 is used alone to prepare the liquid
developer, and the resin of Solution 13 is not used, the developer
is unstable.
EXAMPLE 14
Concentrate 14 is prepared by milling in a ball mill a 1 g. portion
of poly(butyl methacrylate-co-lauryl
methacrylate-co-dimethylaminoethyl methacrylate-co-acrylic acid),
78:16:4:2 by weight, 1 g. of the pigment of Example 9 and 20 ml. of
Solvesso 100. Solution 14 is prepared by dissolving 1 g. of
poly(styrene-co-lauryl methacrylate-co-2-sulfoethyl methacrylate,
38:52:10 by weight, in 20 ml. of Solvesso 100. A liquid developer
is made by combining 3.2 g. of Concentrate 14 with 3.4 ml. of
Solution 14, and adding the mixture dropwise to 326 ml. of Isopar G
under conditions of high shear. When used to develop an
electrostatic charge pattern as in the previous Examples, the
developer gives a high density image and has good density control.
When transferred as previously indicated, the image has high,
uniform density on the transfer sheet. A developer made using
Concentrate 14 alone, in the absence of Solution 14, agglomerates
in the mixing container. Similar results are obtained by using 5.1
ml. of the following Solution 14a in place of the 3.4 ml. of
Solution 14 and mixing with Concentrate 14 to form the developer.
Solution 14a contains 1 g. of poly(styrene-co-lauryl
methacrylate-co-2-sulfoethyl methacrylate), 46:46:8 by weight
dissolved in 20 ml. of Solvesso 100.
EXAMPLE 15
Concentrate 15 is prepared by milling in a ball mill a 1 g. portion
of the lithium salt of poly(butyl methacrylate-co-lauryl
methacrylate-co-sulfoethyl methacrylate), 76:16:8 by weight, 1 g.
of the pigment of Example 5, and 20 ml. of Solvesso 100. Solution
15 is prepared by dissolving 1 g. of the partial sodium salt of
poly(styrene-co-lauryl methacrylate-co-2-sulfoethyl methacrylate),
38:52:10, in 20 ml. of Solvesso 100. A liquid developer is made by
combining 3.2 g. of Concentrate 15 with 3.4 ml. of Solution 15, and
adding the mixture dropwise as in the previous Examples to 326 ml.
of Isopar G. The resulting developer has good marking
characteristics and good density control. A developer made using
Concentrate 15 alone and not containing Solution 15 is not stable
and agglomerates very shortly after preparation.
EXAMPLE 16
Concentrate 16 is prepared by milling in a ball mill a 1 g. portion
of poly(ethyl acrylate-co-ethyl methacrylate-co-lauryl
methacrylate-dimethylaminoethyl methacrylate-co-acrylic acid),
36:30:16:12:6 by weight, 1 g. of the pigment of Example 9, and 20
ml. of Solvesso 100. Solution 16 is prepared by dissolving 1 g. of
the lithium salt of poly(styrene-co-lauryl
methacrylate-co-2-sulfoethyl methacrylate), 48:48:8 by weight, in
20 ml. of Solvesso 100. A liquid developer is made by combining 3.2
g. of Concentrate 16 with 3.4 ml. of Solution 16, and adding the
mixture dropwise to 326 ml. of Isopar G by the technique of the
previous Examples. When used to develop an electrostatic charge
pattern by the method of the previous Examples, the developer
produces a high density image which transfers uniformly and
completely to a transfer sheet. After extended use, when developed
density falls off, the developer is readily replenished to its
initial condition by adding an amount of Concentrate 16 and
Solution 16 corresponding to the amount of pigment and resin which
has deposited on the image-bearing members which have been
developed.
EXAMPLE 17
Concentrate 17 is prepared by milling as in the previous Examples a
1 g. portion of the lithium salt of poly(ethyl acrylate-co-ethyl
methacrylate-co-lauryl methacrylate-co-2-sulfoethyl methacrylate),
46:26:16:12 by weight, 1 g. of the pigment of Example 7, and 20 ml.
of Solvesso 100. Solution 17 is the same as Solution 16 of the
previous Example. A liquid developer is made by combining 3.2 g. of
Concentrate 17 with 5.1 ml. of Solution 16, and adding the
resultant mixture to 324 ml. of Isopar G, dropwise. The developer
has good density control, and forms a dense image on an
electrostatic charge pattern carried on an electrophotographic
imaging member. Transfer of the toner image to a paper transfer
sheet gives virtually complete and uniform transfer.
EXAMPLES 18, 19, 20 and 21
Concentrates 18 - 21 are prepared from the lithium, barium, zinc
and cobalt salts, respectively, of poly(ethyl acrylate-co-ethyl
methacrylate-co-lauryl methacrylate-co-acrylic acid), 46:34:16:4 by
weight. Each contains 1 g. of the polymer dissolved in 20 ml. of
Solvesso 100, and also 1 g. of the pigment of Example 8. The salts
are prepared by dissolving the polymer in water, adding a molar
excess of the acetate of the appropriate metal, and isolating the
polymer. Solutions 18 - 21 each contain 1 g. of the lithium salt of
poly(styrene-co-lauryl methacrylate-co-methacrylic acid) dissolved
in 20 ml. of Solvesso 100. Liquid developers are made by combining
3.2 g. of the appropriate concentrate with 5.1 ml. of one of the
Solutions, after milling the ingredients of the Concentrates to
form the concentrate, and dispersing the mixture under high shear
into 323 ml. of Isopar G. The resulting developer is used to
develop an electrostatic charge pattern on an organic
photoconductive element, and the resultant image transfers well to
a receiving element. Each of the developers has excellent
replenishment characteristics.
EXAMPLE 22
Concentrate 22 is prepared by milling as in previous Examples a 1
g. portion of poly(butyl methacrylate-co-lauryl
methacrylate-co-2-sulfoethyl methacrylate), 76:16:8 by weight, 1 g.
of the pigment of Example 7, and 20 ml. of Solvesso 100. Solution
22 is prepared by dissolving 1 g. of poly(lauryl
methacrylate-co-2-sulfoethyl methacrylate), 92:8 by weight, in 20
ml. of Solvesso 100. A liquid developer is made by mixing 3.2 g. of
Concentrate 22 with 5.1 ml. of Solution 22 and adding the mixture
thus prepared to 324 ml. of Isopar G under conditions of high
shear. When used to develop electrostatic charge patterns, the
developer gives high density and good marking characteristics. The
image transfers cleanly and completely to a transfer sheet.
Replenishment of the developer with addition of a suitable amount
of Concentrate 22 and Solution 22 after some depletion has occurred
restores the initial condition of the developer.
Type A polymers of the type hereinbefore described are also useful
for stabilizing polymers known in liquid developers of the prior
art. Such polymers may be of types chemically well characterized,
or they may be trade-named polymers which may, in certain
situations, have variable compositions. It has been found that in
those situations in which the stability is marginal or poor, the
Type A polymers herein described greatly enhance the stability and
their use results in developers having exceptionally long life and
good marking and transfer properties.
EXAMPLE 23
Concentrate 23 is prepared in two separate parts by milling
together, for each part, 16 g. of pigment, 14.4 g. of Beckosol 7,
53.2 g. Amberol ST-137 and 86.4 g. of Solvesso 100. The first part
contains Rhodamine Y as pigment; the second, Cerise T (see Example
4 for a characterization of the pigments). Beckosol 7 is a soya
modified alkyd sold by Reichold Chemicals, Inc. Amberol ST-137 is a
reactive unmodified phenol formaldehyde resin sold by Rohm and Haas
Company. The two parts are combined into a single concentrate.
Solution 23 is prepared by dissolving 1 g. of the partial sodium
salt of poly(styrene-co-lauryl methacrylate-co-3-sulfopropyl
methacrylate), 46:50:4 by weight, in 100 g. of Solvesso 100. A 3.3
ml. portion of Concentrate 23 is mixed with a 25 ml. portion of
Solution 23, and a liquid developer made therefrom by slowly adding
the mixture to 472 ml. of Isopar G under high shear. An
electrostatic charge pattern formed by exposing a charged organic
photoconductive element to a continuous-tone image is then
developed with the developer. A good reproduction of the image
results. A developer prepared as above but without the terpolymer
agglomerates immediately upon dispersion into the Isopar. When
poly(styrene-co-lauryl methacrylate-co-dimethylaminoethyl
methacrylate-co-2-sulfoethyl methacrylate), 44:43:6:7 by weight, is
used in preparing Solution 23, a stable developer with negatively
charged particles results. Carbon black may be used in place of
colored pigments.
EXAMPLE 24
Concentrate 24 is prepared by milling together 1 g. of poly(butyl
methacrylate-co-lauryl methacrylate), 70:30 by weight, 1 g. of
yellow pigment (C.I. 21100) and 20 ml. of Solvesso 100. Solution 24
is prepared by dissolving 1 g. of the sodium salt of
poly(styrene-co-lauryl methacrylate-co-3-sulfopropyl methacrylate),
47:43:10 by weight, in 20 ml. of Solvesso 100. Concentrate 24 and
5.1 ml. of Solution 24 are mixed together and the mixture added
gradually to 324 ml. of Isopar G under high shear, as before. There
results a stable developer dispersion having good density control
and capable of producing a dense image on an organic
photoconductive element bearing an electrostatic charge pattern. If
a developer is prepared not using Solution 24, the resultant
mixture agglomerates immediately upon addition of the Concentrate
to the Isopar.
EXAMPLE 25
Three concentrates are prepared by milling together, for each
concentrate, 1 g. of the pigment of Example 7 with 1 g. of polymer
as follows and 20 ml. of Solvesso 100:
Concentrate Polymer ______________________________________ 25A
poly(butyl methacrylate-co- lauryl methacrylate-co- acrylic acid),
80:16:4 by weight 25B same; 76:16:8 by weight 25C same; 72:16:2 by
weight ______________________________________
Three solutions are prepared, each containing 1 g. of the partial
sodium salt of poly(styrene-co-lauryl methacrylate-co-3-sulfopropyl
methacrylate), 50:46:4. One of the solutions is combined with one
of Concentrates 25A, 25B and 25C, and each of the remaining two
with one of the remaining Concentrates. A 3.2 g. portion of
Concentrate and a 1.7 ml. portion of Solution is used in each
instance. The resulting mixture is slowly added to 328 ml. of
Isopar G under high shear conditions as before to produce, for each
concentrate, a separate liquid developer. Each of the developers
thus obtained is used to develop an electrostatic charge pattern. A
good reproduction of the pattern results in each case. Each image
transfers cleanly and uniformly to a transfer sheet. Developers
made using the concentrates alone in the absence of the resins
contained in the solutions agglomerate immediately upon addition of
the concentrate to the Isopar.
EXAMPLE 26
Solution 26A is prepared by dissolving 1 g. of the lithium salt of
poly(butyl methacrylate-co-2-sulfoethyl methacrylate) 88:12 by
weight in 19.2 ml. of Solvesso 100. Solution 26B is prepared by
dissolving 1 g. of the lithium salts of poly(styrene-co-lauryl
methacrylate-co-methacrylic acid) 50:46:4 by weight in 19.2 ml.
Solvesso 100. A developer is prepared by combining 3.2 g. each of
solutions 26A and 26B and diluting the combination with 326 ml. of
Isopar G while stirring with a magnetic stirrer.
When flowed over the surface of an organic photoconductor element
bearing an electrostatic charge pattern of negative polarity, the
developer produces a virtually colorless image which can be inked
and used as a lithographic printing plate or the image can be
transferred to a hydrophilic surface and then inked.
EXAMPLE 27
Preparation of Poly(styrene-co-lauryl methacrylate-co-lithium
methacrylate)
In 80 ml. of dimethylformamide is dissolved 4 g. of lithium
methacrylate followed by 50 g. of styrene, 46 g. of lauryl
methacrylate and 1 g. of azobisisobutyronitrile. The solution is
flushed with nitrogen and heated at 70.degree.C. for 20 hours. The
resultant polymer solution is diluted with 100 ml. of dioxane and
poured into cold water with vigorous agitation to precipitate the
product which has an inherent viscosity in chloroform of 0.3.
EXAMPLE 28
Preparation of Poly(ethyl acrylate-co-ethyl methacrylate-co-lauryl
methacrylate-co-sulfoethyl methacrylate, lithium salt)
Into 12 g. of sulfoethyl methacrylate in 200 ml. of
dimethylformamide is stirred 2.6 g. of lithium hydroxide
monohydrate until solution occurs. To the solution is added 46 g.
of ethyl acrylate, 26 g. ethyl methacrylate, 16 g. of lauryl
methacrylate and 2 g. of azobisisobutyronitrile. The solution is
flushed with nitrogen and heated at 70.degree.C. for 20 hours to
form the polymer. Evaporation of the solvent gives a product which
has an inherent viscosity in chloroform of 0.2.
Liquid developers can be prepared using the polymer and polymer
mixtures described above without adding any colorant material such
as pigment. In such case, solvent milling to blend together the
pigment and the polymer is unnecessary. This type of liquid
developer free from colorant may be used to develop permanent
images from electrostatic charge patterns, which permanent images
have little or no color. If one is interested simply in producing
an ink-receptive image or forming a substantially colorless,
patterned overcoat, this type of colorant-free liquid developer is
quite useful.
The invention has been described in detail with particular
reference to preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *