U.S. patent number 3,900,412 [Application Number 05/355,567] was granted by the patent office on 1975-08-19 for liquid toners with an amphipathic graft type polymeric molecule.
This patent grant is currently assigned to Philip A. Hunt Chemical Corporation. Invention is credited to George E. Kosel.
United States Patent |
3,900,412 |
Kosel |
August 19, 1975 |
Liquid toners with an amphipathic graft type polymeric molecule
Abstract
A liquid toner with a number of solids less than those
conventionally used in a multi-component liquid toner, obtained by
combining the functional characteristics of plural previous
different kinds of solids into a complex molecule, thereby
obtaining better image fixation, improved resistance to
preferential depletion, improved image definition, clear
background, improved shelf life, improved functional life and a
broad color range.
Inventors: |
Kosel; George E. (Park Ridge,
NJ) |
Assignee: |
Philip A. Hunt Chemical
Corporation (Palisades Park, NJ)
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Family
ID: |
26676726 |
Appl.
No.: |
05/355,567 |
Filed: |
April 30, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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7253 |
Jan 30, 1970 |
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810841 |
Mar 26, 1969 |
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Current U.S.
Class: |
430/114; 430/115;
430/904 |
Current CPC
Class: |
G03G
9/1355 (20130101); C08F 2/08 (20130101); G03G
9/133 (20130101); Y10S 430/105 (20130101) |
Current International
Class: |
C08F
2/08 (20060101); C08F 2/04 (20060101); G03G
9/12 (20060101); G03G 9/13 (20060101); G03G
9/135 (20060101); G03g 009/04 () |
Field of
Search: |
;96/1LY ;117/37LE
;260/22,33.6 ;252/62.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Torchin; Norman G.
Assistant Examiner: Goodrow; John L.
Attorney, Agent or Firm: Kirschstein, Kirschstein, Ottinger
& Frank
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATION
This is a division of application Ser. No. 7,253 filed Jan. 30,
1970 now abandoned which is a continuation-in-part of application
Ser. No. 810,841 filed March 26, 1969 for LIQUID TONERS, now
abandoned.
Claims
Having thus described the invention, there is claimed as new and
desired to be secured by Letters Patent:
1. A liquid electrostatographic toner essentially comprising a
liquid solvent system, amphipathic polymeric molecules of the graft
type each having a polymeric backbone part and a polymeric graft
part on said backbone part, each of said molecules being composed
of two moieties of which at least one is thermoplastic, said first
moiety, which is one of said parts, being solvated by said system,
a portion of said first moiety being a dispersant and a fixative to
bond the molecules to a substrate, and a second moiety, which is
the other of said parts, being insoluble in said system, said
second moiety having a particle size between 25m.mu. and 25.mu., a
portion of said second moiety being a fixative to bond the
molecules to a substrate, so that there is provided a continuous
phase constituting the solvent system with the first moieties of
the molecules dissolved therein and a dispersed phase constituting
the non-solvated moieties of the molecules whereby said molecules
act as a mono-dispersed particle phase, a fixative and a
dispersant, and a charge director.
2. A liquid toner as set forth in claim 1 which further includes a
color agent.
3. A liquid toner as set forth in claim 1 wherein the charge
director imparts a resistivity to the toner of from 10.sup.14 to no
less than 10.sup.9 ohms cms.
4. A liquid toner as set forth in claim 1 wherein the charge
director imparts a resistivity to the toner of from 10.sup.13 to
10.sup.10 ohms cms.
5. A liquid toner as set forth in claim 1 wherein the charge
director imparts a resistivity to the toner of from 2 .times.
10.sup.12 to 10.sup.11 ohms cms.
6. A liquid toner as set forth in claim 2 wherein a color agent is
a moiety of the amphipathic molecule.
7. A liquid toner as set forth in claim 2 wherein the color agent
is a compound other than the amphipathic molecule.
8. A liquid toner as set forth in claim 1 wherein the amphipathic
molecule includes a solvated moiety selected from the class
consisting of crepe rubber; refined linseed oil; degraded rubber;
alkyd resins, polyisobutylene; polybutadiene; polyisoprene;
polyisobornyl methacrylate; homopolymeric vinyl esters of long
chain fatty acids; homopolymeric vinyl alkyl ethers; homopolymers
of the C.sub.4 -C.sub.22 alkyl esters of acrylic and methacrylic
acid in a molecular weight range of about 10.sup.3 to about
10.sup.6 ; copolymers of the aforesaid C.sub.4 -C.sub.22 alkyl
esters with one another; copolymers of the aforesaid C.sub.4
-C.sub.22 alkyl esters with one another and with methyl, ethyl,
isopropyl and propyl esters of acrylic and methacrylic acids;
copolymers of the C.sub.4 -C.sub.22 alkyl esters of acrylic and
methacrylic acids with monomers containing acrylic acid,
methacrylic acid, crotonic acid, maleic acid, atropic acid, fumaric
acid, itaconic acid, citraconic acid, acrylic anhydride,
methacrylic anhydride, maleic anhydride, acryloyl chloride,
methacryloyl chloride, acrylonitrile, methacrylonitrile, N-vinyl
pyrrolidone, acrylamide and derivatives thereof, methacrylamide and
derivatives thereof, hydroxyethyl methacrylate, hydroxyethyl
acrylate, hydroxypropyl methacrylate, hydroxypropyl acrylate,
dimethylaminomethyl methacrylate, dimethylaminomethyl acrylate,
dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate,
diethylaminomethyl methacrylate, diethylaminomethyl acrylate,
diethylaminoethyl methacrylate, diethylaminoethyl acrylate,
t-butylaminoethyl methacrylate, t-butylaminoethyl acrylate,
cyclohexyl acrylate, allyl alcohol and derivatives thereof,
cinnamic acid and derivatives thereof, styrene and derivatives
thereof, butadiene, methallyl alcohol and derivatives thereof,
propargyl alcohol and derivatives thereof, indene and derivatives
thereof, norbornene and derivatives thereof, vinyl ethers, vinyl
esters, vinyl derivatives other than vinyl ethers and vinyl esters,
glycidyl methacrylate, glycidyl acrylate, mono- and dimethyl
maleate, mono- and dimethyl fumarate, mono- and diethyl maleate and
mono- and diethyl fumarate; condensation polymers; copolymers of
butadiene, isoprene and isobutylene with C.sub.4 -C.sub.22 alkyl
esters of acrylic and methacrylic acids; polycarbonates;
polyamides; polyurethanes and epoxies, and the nonsolvated moiety
comprises homopolymers and copolymers formed from monomers selected
from the class consisting of vinyl acetate, vinyl chloride, methyl
acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate,
propyl acrylate, propyl methacrylate, isopropyl acrylate, isopropyl
methacrylate, hydroxy ethyl acrylate, hydroxy ethyl methacrylate,
hydroxy propyl acrylate, hydroxy propyl methacrylate,
acrylonitrile, methacrylonitrile, acrylamide, methacrylamide,
acrylic acid, acrylic anhydride, methacrylic acid, methacrylic
anhydride, mono methyl maleate, mono methyl fumarate, mono ethyl
maleate, mono ethyl fumarate, styrene, vinyl toluene, maleic acid,
maleic anhydride crotonic acid, crotonic anhydride, fumaric acid,
atropic acid, allylamine, vinyl amine, allyl alcohol, vinyl
pyridines and derivatives thereof, glycidyl acrylate, glycidyl
methacrylate, dialkylaminoalkyl methacrylate, dialkylaminoalkyl
acrylate, methacrylyl acetone, N-hydroxymethyl methacrylamides,
alkoxymethyl methacrylamides, acryloyl chloride, methacryloyl
chloride, vinyl isocyanate, cyanomethylacrylate, vinyl
.beta.-chloroethylsulphone, vinyl sulphonic acid and vinyl
phosphoric acid.
9. A liquid toner as set forth in claim 1 wherein the charge
director is selected from the class consisting of di-2-ethylhexyl
sodium sulfosuccinate; di-tridecyl sodium sulfosuccinate; aluminum,
chromium, zinc and calcium salts of 3, 5-dialkylsalicylic acid,
wherein the alkyl group is propyl, isopropyl, butyl, isobutyl,
tertiary butyl, amyl, isoamyl and other alkyl groups up to C-18;
aluminum, chromium, zinc and calcium salts of dialkyl
gamma-resorcylic acid, wherein the alkyl is as above;
isopropylamine salt of dodecylbenzene sulfonic acid; aluminum,
vanadium and tin dresinates; aluminum stearate; cobalt, iron and
manganese octoates; a partially imidized polyamine with
lubricating-oil-soluble polyisobutylene chains and free secondary
amines, gravity at 60.degree.F API 22.9, specific 0.92, flash point
by the Cleveland open cup method, 425.degree.F, viscosity at
210.degree.F, 400 SSU, color (ASTM D-1500) L55D, nitrogen,
percentage by weight 2.0, and alkalinity value, (SM-205-15) 43;
soya bean lecithin, an aluminum salt of 50/50 by weight mixture of
the mono- and di-2 ethylhexyl esters of phosphoric acid, and a
terpolymer consisting of 50 percent by weight octadecenyl,
methacrylate, 40 percent by weight styrene, and 10 percent by
weight diethylaminoethyl methacrylate.
10. A liquid toner as set forth in claim 1 wherein the amphipathic
molecule includes a backbone chain of comonomers and attached
chains having attached sites of a precursor monomer derived from
monomers selected from the affiliated monomer groups set forth
below:
11. A liquid toner as set forth in claim 1 wherein the solvent
system is a liquid petroleum fraction.
12. A liquid toner as set forth in claim 11 wherein the liquid
petroleum fraction has an electrical resistivity of at least
10.sup.9 ohm cm., a dielectric constant of less than three and
one-half, a TCC flash point of 100.degree.F. to 152.degree.F. and a
viscosity of 0.5 to 2.5 centipoises at room temperature.
13. A liquid toner as set forth in claim 2 wherein the chromophore
is selected from the class consisting of powdered metals, powdered
metal oxides, powdered metal salts, acetamine black CBS, nigrosine
base No. 424, Hansa Yellow G, spirit nigrosine SSB, Rubanox Red
CP-1495 and carbon black.
14. A liquid toner as set forth in claim 1 wherein the solvated
moiety is poly (lauryl methacrylate - glycidyl methacrylate-
methacrylic acid).
15. A liquid toner as set forth in claim 14 wherein the
non-solvated moiety is poly (vinyl acetate).
16. A liquid toner as set forth in claim 14 wherein the
non-solvated moiety is poly (vinyl
acetate/N-vinyl-2-pyrrolidone).
17. A liquid toner as set forth in claim 14 wherein the
non-solvated moiety is poly (vinyl acetate/crotonic acid).
18. A liquid toner as set forth in claim 14 wherein the
non-solvated moiety is poly (vinyl acetate/methyl hydrogen
maleate).
19. A liquid toner as set forth in claim 1 wherein the solvated
moiety is poly (isodecyl methacrylate-glycidyl methacrylate -
methacrylic acid).
20. A liquid toner as set forth in claim 19 wherein the
non-solvated moiety is poly (vinyl acetate).
21. A liquid toner as set forth in claim 1 wherein the solvated
moiety is poly (stearyl methacrylate - glycidyl methacrylate -
methacrylic acid).
22. A liquid toner as set forth in claim 1 wherein the solvated
moiety is poly (lauryl methacrylate - glycidyl methacrylate -
methacrylic acid - chromophore).
23. A liquid toner as set forth in claim 1 wherein the solvated
moiety is poly (lauryl methacrylate - N-1,1,3,3tetramethyl butyl
methacrylamide - glycidyl methacrylate - methacrylic acid).
24. A liquid toner as set forth in claim 1 wherein the non-solvated
moiety includes a polymer having recurring units of methyl hydrogen
maleate.
25. A liquid toner as set forth in claim 1 wherein the non-solvated
moiety is a poly (vinyl acetate/methyl hydrogen maleate).
26. A liquid toner as set forth in claim 6 wherein the chromophore
is a dye selected from the class consisting of Pontacyl Brilliant
Blue A (Dupont) (C.I. Acid Blue 7); Calcocid Brilliant Blue FFR
(American Cyanamid) (C.I. Acid Blue 104); Femazo Brown N (General
Aniline) (C.I. Acid Brown 14); Crocein Scarlet N (Dupont) (C.I. Red
73); Oxanal Yellow I (Ciba) (C.I. Acid Yellow 63); Benzyl Black 4BN
(Ciba) (C.I. Black 26A); Magenta (C.I. Solvent Red 41, C.I. No.
42510B); Crystal Violet (C.I. Solvent Violet 9, C.I. No. 42555B);
Bismarck Brown (C.I. Solvent Brown 12, C.I. No. 21010B); Victoria
Blue BA (C.I. Solvent Blue 4, C.I. No. 44045B); Victoria Blue R
(C.I. Solvent Blue 6, C.I. No. 44040R); Victoria Blue 4R (C.I.
Solvent Blue 2, C.I. No. 42563B); Copying Black SK (C.I. No.
11975); Janus Green B (C.I. No. 11050); Auramine 0 (C.I. Solvent
Yellow 34, C.I. No. 4100B); Victoria Green (C.I. Solvent Green 1,
C.I. No. 42000B); and Rhodamine (C.I. Solvent Red 49, C.I. No.
45170B).
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
A liquid toner including an amphiphatic molecule made up of various
polymeric moieties having different functions, of which one may be
to impart a color, that are desirable for toner use, at least one
of which is solvated and another non-solvated by a liquid carrier
system.
2. Description of the Prior Art
Prior art liquid toners as well as liquid toners of the present
invention can be used for several purposes which can be generally
grouped under the heading of selective deposition on a substrate.
For example, the toners can be employed to form on a sheet a
visible pattern which may be a picture, including a half-tone
picture, a line picture, or a photographic reproduction or a
symbol, or a digit, or a graph, or a letter of an alphabet. The
widest present-day use of liquid toners and the principal use of
the liquid toner of the present invention is as a liquid
electrostatographic developer for office copy apparatus. However,
it is to be understood that the liquid toners of the present
invention are not thus limited in their utility and may also be
employed for high speed print-outs and reproductions, ink jet
printing, enlarged reproductions of microfilms, facsimile printing,
instrument recording, etc.
Prior art liquid toners can, in general, be categorized into two
classes which for convenience will be referred to as conventional
liquid toners and liquid toners based on toner powders.
A conventional liquid toner constitutes a dispersion of pigments,
the dispersed phase, in a liquid hydrocarbon system, the continuous
phase. The liquid hydrocarbon system conventionally is
characterized by the attributes of: (a) quick evaporation, that is
to say, a thin film of this system will evaporate in a few seconds
at a temperature below the char point of paper, so as to permit
fast drying; (b) nontoxicity when applied to the human skin or
inhaled along with air; (c) low odor, so that it can be used in a
machine which is located in an ill-ventilated room; (d) full
drying, i.e., when employed with film forming agents, it will fully
escape from a deposited film, so as to leave the film liquid-free
and not subject to evaporation over protracted periods of time
after a deposited graphic representation is seemingly dry; (e)
sufficient fluidity to allow the particles of solid suspended
material which are to be attracted to a copy sheet for the
formation of a graphic representation to migrate therethrough with
ease, so that, particularly where such material is
electrostatographically attracted, it can be quickly attracted to
and coupled with the patterning of electrostatic charges which is
to be visibly reproduced by development with the toner; (f)
physical and chemical inertness to the coating binder used on copy
sheets, so that it will not attack the same; (g) the ability not to
bleed off the electrostatic charges on the copy sheet before the
graphic representation is visually formed, whereby to maintain any
desired degree of contrast; and (h) low cost.
Typically, the liquid hydrocarbon system has been a petroleum
fraction which inherently includes the aforesaid attributes. Such
fraction preferably has had certain specific physical
characteristics which are the same as those of a preferred liquid
carrier system used in the present invention and which, since the
same will be described in detail hereinafter, will not be listed at
this point.
The continuous phase (liquid system) of a conventional liquid toner
has had present therein, some dissolved in it and others suspended
in it, certain solids which have functional attributes that are
desirable for proper operation of the process involved, usually
electrostatographic development. These solids are: (a) pigment
particles; (b) a fixative which usually is a thermoplastic resin,
the ability to flow under heat being sometimes desirable to
increase the bond between the selectively deposited material and
the copy sheet by subjecting the substrate with deposited material
thereon to a temperature sufficiently high to fuse the deposited
material and thereby improve its interphase relationship with the
substrate; (c) a dispersant which usually is a long chain organic
compound such as a synthetic polymer with some oil soluble and some
polar groups, e.g., FOA 2, lube oil 564 and lecithin, these
substances being specifically identified in copending application
Ser. No. 767,031 filed Sept. 11, 1968 for LIQUID DEVELOPER FOR
ELECTROSTATOGRAPHY, now U.S. Pat. No. 3,669,886 issued June 13,
1972, the purpose of the dispersant being to disperse solid
particles present, e.g., the pigment particles, so as to prevent
them from settling, this lengthens the shelf life, prevents caking
and is believed to enhance the ability of the solid particles
present to migrate through the continuous phase, and (d) a charge
director which usually is a metallic derivative of a fatty acid or
a resin acid. Typical pigment particles, fixatives, charge
directors and dispersants are detailed in the aforesaid application
Ser. No. 767,031. The charge director is adsorbed by the individual
pigment particles and behaves in some manner, the physical
explanation for which is not fully comprehended but is believed to
be a surface phenomenon, to cause pigment aggregates to be formed
in the dispersed phase. The dispersion of these aggregates is
stabilized by the dispersant via an entropic repulsion mechanism.
The foregoing is an extremely condensed description of conventional
toners, very broadly considered and without detailing the many
sophisticated approaches that have been made in attempts to obtain
commercially acceptable conventional liquid toners.
The second type of liquid toner, to wit, the one based on toner
powders utilizes a preground dry toner powder, such as a finely
comminuted electroscopic colored material, for instance, a mixture
of carbon black and polystyrene, as the dispersed phase, and a
liquid hydrocarbon system, such as the one above described, as the
continuous phase. The toner powders of the second type of liquid
toner are distinguished from the pigments used in conventional
liquid toners in that the order of particle size of the toner
powders used in the second type of liquid toner is two to three
orders larger than the particle size of the pigments in a
conventional liquid toner. The continuous phase of liquid toners
based on toner powders usually contains a charge director which
commonly is dissolved or dispersed in the continuous phase and the
continuous phase generally is of a higher viscosity than is the
continuous phase of a conventional toner, so as to hinder, i.e.
impede, the settling of these large toner particles. The second
type of liquid toner also usually contains a fixative.
Both of these conventional types of liquid toners have certain
inherent defects which largely are caused by the fact that (a) the
solid components of the toners constitute several compounds, some
of which have overlapping functions, but each of which is highly
desirable or even necessary for different major functions, and (b)
unevenness of particle size of undissolved particles.
One defect is the particle size distribution of the dispersed
phase. In conventional toners not all of the pigment particles of
the dispersed phase are included in the aggregates formed under the
influence of the charge director. For reasons as yet undetermined
by physical chemists, some of these pigment particles are suspended
relatively free of other particles and of aggregates. These
unaggregated particles are of very small size, probably in the
millimicron size range, and sometimes are referred to as "fines".
They tend to be deposited in non-image areas and create an overall
light colored, e.g., grayish, background that distinguishes liquid
toners from dry toners. It is well recognized in the art that the
background discoloration is far less noticeable with dry toners
than with liquid toners and this is one of the principal reasons
that liquid toners have had great difficulty in making a deep
inroad in apparatuses employing toners.
With toner powder based liquid developers, with their larger
particle size, the particle size distribution of the dispersed
phase is more uniform so that the background areas are virtually
free of toner particle deposition; however, because of the very
largeness of the particle size, it has not been possible to develop
formulations which prevent the toner particles from settling out so
that the shelf life of these latter developers is relatively short
and the deposited particles tend to cake, making it difficult after
they have stored for any appreciable length of time to redisperse
them easily and quickly by shaking. Not only that but this large
particle size tends to lead to poor resolution, so that small
details are lost or are obliterated, i.e., run together into larger
areas of a graphic representation. It would be ideal, although this
has not been accomplished before the present invention, to have a
mono-dispersed particle size distribution, i.e., a substantially
identical particle size of the dispersed phase which is larger than
that present in a conventional toner, so as to eliminate fines, but
smaller than that of the toner powder based liquid developers, so
as to secure satisfactory resolution and inhibit settling unless
the settling can be otherwise controlled.
Another defect of previous liquid toners arises from the fact that
the liquid toner is used in an apparatus that is in continuous
operation. As the apparatus functions on a minute to minute, hour
to hour and day to day basis, the liquid toner is being used up and
must be replenished. Superficially, this might seem to be a simple
matter. It would appear that all one would have to do is add more
of the solids and/or more of the continuous phase, either in the
form of more liquid toner, more liquid system, or a concentrate of
liquid toner. However, due to various causes, the sundry components
of a liquid toner chemical system, and particularly of a liquid
electrostatographic system, deplete at different rates, the rates
fluctuating, for instance, as functions of the stress applied to
the liquid toner system, for example, more or less image area per
print, and more or less solvent carry-out per print, this latter
being dependent on developer tray configuration, roller tension,
bath volume, overflow, recirculation rate and paper velocity. Other
causes are the different volatilization rates of the different
compounds, the temperature of the developing stage, the different
rates of print pick up for the different compounds, and the
different potentials of different parts of the latent electrostatic
image. These causes are not intended to be a complete list of all
of the variables which causes the components to be depleted at
different rates.
Thus, as a practical matter, it is physically impossible to
replenish such a liquid toner system in a manner such as to
maintain it at its optimum capability even for the major part of
its life. The more components that are present a system, and as
will be realized from the aforesaid description of the prior art
liquid toners there are many components, the worse this problem of
preferential depletion and replenishment becomes. It simply is not
practical to replenish the various components at the different
rates at which they are depleted. To do this, even on one machine,
would be an economic waste. To do it generally on copy machines is
utterly impractical. Hence, as a tolerable practice, it has been
customary to replenish liquid toners with concentrates having
roughly the proportions of the solids in the original liquid
toners, whereby as the replenished toner in the apparatus is used
more and more, the quality of the patterned deposit progressively
is degraded until finally a point is reached where whatever liquid
toner is present in the equipment is discarded and a completely
fresh bath of liquid toner substituted for the same. Prior to the
present invention, it has not been possible to solve this problem
because the number of solid components could not be minimized.
Another problem which has seriously plagued various types of
electrostatic apparatuses that employ a liquid toner is slow fixing
speed. This becomes most noticeable and serious in equipment which
is required to deliver electrostatically developed material at
extremely high rates of speed. At the present time it requires
several minutes for an electrostatically developed image to be
sufficiently dried, in the absence of a separate heater, to be
handled in equipment, e.g., by rolling up or fanfolding, without
smearing the freshly developed print. To avoid this, resort often
has been had to extremely high output heaters which unnecessarily
complicate and raise the prices of the equipment and call for
considerable amounts of space as well as cooling mechanisms and
high-power electric lines. All of this has retarded the widespread
use of liquid toners. This initial smearability of
electrostatically developed image is not to be confused with the
smearability of fully dried images, e.g., copies in the hands of a
user to whom substrates such as paper bearing these images are
delivered possibly hours or days later.
Furthermore, the same problem of the inability of present liquid
toners to be rapidly initially fixed is present in computer
read-outs and like equipment which deliver information at very
rapid rates. A computer is capable of delivering literally billions
of characters per second. But there is no liquid toner which can
begin to approximate development thereof at an equivalent speed.
About the best that can be done with presentday equipment is 90 -
120 inches of copy per minute, or 9,000 sheets per hour, and often
this requires other types of printing, i.e., printing not using
electrostatic methods, e.g., impact printing. It would be extremely
desirable to provide an electrostatic liquid toner which is capable
of very rapid fixation, i.e., fixation which renders an image
virtually smear-proof to mechanical handling within 20 seconds
after leaving a development bath.
A further problem in the prior art in connection with liquid
electrostatic toners is the difficulty the art has had, despite
conscientious attempts to provide the same, to supply a liquid
toner which is capable of being efficiently issued as a jet and
electrostatically directed. To date the only such toners available
are subject to many drawbacks which, although indicating the
tremendous commercial feasibility of this new style of printing,
have not yet rendered it sufficiently acceptable for general
commercial use.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved and
unique liquid toner having a mono-dispersed phase of a particle
size which is intermediate those of the fines of conventional
toners and those of the pigment particles of toner based liquid
toner powders, i.e., in excess of 25m.mu. and not greater than
25.mu. and a reduced number of kinds of solid components present in
this mono-dispersed phase, whereby to reduce and to minimize the
preferential depletion of toners of the prior art types.
It is another object of the invention to provide a liquid toner of
the character described which has a superior fixation of the
selective deposition so that the same will be virtually
smear-proof.
It is another object of the invention to provide a liquid toner of
the character described which has a substantially improved
resistance to preferential depletion of component parts of the
liquid toner during its use, e.g., in a reproduction machine that
is employed in either continuous or intermittent operation.
It is another object of the invention to provide a liquid toner of
the character described having a selective deposition definition as
good as that of a conventional toner and yet with virtual
elimination of background color, that is to say, elimination of
non-image area deposition of colored particles.
It is another object of the invention to provide a liquid toner of
the character described which has an improved and, indeed, to all
intents and purposes, an indefinite, resistance to settling so that
there is a concomitant greatly increased shelf life.
It is another object of the invention to provide a liquid toner of
the character described having an improved functional life, that is
to say, a liquid toner which will provide more square inches of
selective deposition than previous toners per unit of solids with a
decreased frequency of replenishment and an improved economic and
efficient utilization of the toner.
It is another object of the invention to provide a liquid toner of
the character described which can be based upon any solvent system
that is useful in a liquid toner employing apparatus, that is to
say, any solvent system which is compatible with the apparatus
being employed and the demands of the selective deposition method,
as, for example, any solvent system that can be used to develop an
electrostatographic image.
It is another object of the invention to provide a liquid toner of
the character described which is capable of making visible
selective depositions of any desired color and any desired depth of
color.
It is another object of the invention to provide a liquid toner of
the character described which is particularly fast-setting in its
initial stages so as to rapidly leave an image which, although
still fresh, is smear-proof for machine handling, so that a
substrate on which this image has been deposited can, within a
comparatively short time, e.g., as little as 20 seconds, be safely
manipulated without fear of spoiling the image, as, for instance,
it can be rolled up or manifolded.
It is another object of the invention to provide a liquid toner of
the character described which, by virtue of its very fast initial
fixing, can be employed in electrostatic image development in
equipment which has extremely high speed outputs of substrates
bearing images, such, for instance, as computer read-outs or
cathode ray tube read-outs or facsimile read-outs or read-outs of
enlarged microfilms or read-outs of mirrordeflected light
beams.
It is another object of the invention to provide a liquid toner of
the character described which can be used with great facility in
ink jet recording; that is to say, a liquid toner which in a
dropleted jet-beam form is capable of being facilely manipulated by
electrostatic deflecting arrangements.
It is another object of the invention to provide a liquid toner of
the character described with which excellent results can be secured
outside of the office copy field, in particular in connection with
high speed electrostatic developing, although the toner is capable
of efficiently handling all normal slower speed electrostatic
developing.
It is another object of the invention to provide a liquid toner of
the character described which functions in an excellent manner with
all types of substrates and all types of latent electrostatic image
recordings, e.g., which will function well with substrates
including any kind of electrographic materials; examples of various
types are conventional zinc oxide resin substrates, organic
photoconductive substrates, titanium dioxide resin substrates and a
substrate constituting a terephthalate dielectric sheet having a
latent electrostatic image thereon imparted by a cathode ray pin
tube. The substrates embraced within the scope of those which can
be employed with the toner of the present invention may either be
actinically sensitive or non-actinically sensitive, that is to say,
the charged substrates can be sensitive to discharge by exposure to
light or may not be thus sensitive.
Other objects of the invention in part will be obvious and in part
will be pointed out hereinafter.
The invention accordingly consists in the compositions of matter
and series of steps which will be exemplified in the materials and
processes hereinafter described and of which the scope of
application will be indicated in the appended claims.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In general, the several objects of the present invention are
accomplished by providing a liquid toner which essentially consists
of a solvent system, a color agent and a complex molecule including
plural polymeric moieties of which at least one is solvated by the
solvent system and at least one is non-solvated by the solvent
system, the color agent optionally being in the form of a moiety of
the molecule in the nature of a chromophore. At least one of the
moieties is of a resinous nature and serves as a fixative. A
non-solvated moiety provides a solid particle in the solvent system
(the continuous phase) enabling the desired size of particles to be
formed and permitting electrophoretic deposition to take place in
the formation of a patterned deposit on a substrate, e.g., enabling
electrostatic attraction to take place between a particle and a
latent electrostatic image on a copy sheet. The solvated moiety
functions to maintain the complex molecule in suspension, that is
to say, to prevent settling of the molecule and hence, in effect,
operates as a dispersing agent. Thus, in the complex molecule,
several functions of previously different solid compounds are
amalgamated. It should be observed that the moiety or moieties
which impart the resinous characteristic to the complex molecule
may be either the solvent solvated moiety or the solvent
non-solvated moiety or both. This complex molecule is a so-called
"tailored" molecule, that is to say, it is an artificially created
molecule which in a single compound provides plural functions
heretofore requiring the presence of plural separate solids which
resulted in preferential depletion and non-uniform or gross pigment
particle size. A charge director is an additional most desirable
component of the liquid toner.
The basic building block of the novel liquid toner of the present
invention is the solvent system. The term "basic building block" is
not used in the sense that the solvent system is the core of the
complex molecule which is employed pursuant to the present
invention, but rather that the nature of the solvent system
influences the particular type complex molecule that is to be
employed. Once the solvent system has been chosen, certain
parameters of the liquid toner developer solid components, and
specifically of the complex molecule, are indicated, Any type of
solvent system can be used which is compatible with the particular
apparatus and method using any specific form of a liquid toner
embodying the present invention. For instance, the liquid toner of
the present invention could be based upon a non-polar solvent
system such as is conventionally employed in the creation of most
patterned deposits and is widely used in electrostatographic
toners. Nevertheless, the present invention is not limited to a
non-polar solvent system and can be equally well used with a polar
solvent system, where such a system is practical in any specific
apparatus or method that can make use of such a toner. Because the
present large-scale commercial use of liquid toners is with
apparatuses and methods that utilize non-polar solvents, the
following description of the invention as to the particular
examples and compositions stresses solids used with a non-polar
continuous phase, i.e., solvent system.
Such a non-polar solvent system includes an organic non-polar
liquid having the characteristics of those previously mentioned
above and referred to in particular under subdivisions (a) - (h)
which are incorporated here by reference. An excellent and
conventional solvent which is well known and widely used in liquid
electrostatographic toners is a petroleum fraction, this having the
attributes just mentioned. The petroleum fraction, i.e., the
solvent system, in addition to having the aforesaid generalized
physical attributes, has an evaporation rate at least as fast as
that of kerosene, but slower than that of hexane. Thereby, the
evaporation of the liquid from a film will be rapid, e.g., two
seconds, at a temperature slightly below the char point of paper,
it being customary to raise the temperature of the film of liquid
toner to this level for the purpose of evaporating the toner
solvent after the patterned deposition has been formed by
attraction to an electrostatically charged image. The petroleum
fraction has a low K.B. (Kauri-butanol) number, to wit, less than
35, and preferably between 26 and 35. This low K.B. number
minimizes the possibility that the petroleum fraction will attack
the coating binder, e.g., the binder for the zinc oxides used in
electrostatography, or will attack any sizing on the sheet, e.g.,
paper, upon which the coating is applied. The petroleum fraction
also is substantially free of aromatic liquid constituents, e.g.,
is substantially aromatic-liquid-free. This term, as used herein,
connotes that the proportion of aromatic liquids in the organic
liquid carrier is not in excess of two per cent by weight. The
aromatic liquids have a strong tendency to attack the coating
binders, e.g., the coating binders for zinc oxide, but in
concentrations of less than two per cent this tendency is so
negligible as to be unnoticeable. The petroleum fraction has a high
electrical resistivity, e.g., in the order of at least 10.sup.9 ohm
centimeters, and a dielectric constant of less than three and
one-half, so that the liquid carrier will not dissipate the pattern
of electrostatic charges which are to be developed in
electrostatography. The TCC (Tagliabue closed cup) flash point of
the liquid carrier is at least 100.degree.F. and preferably about
120.degree.F. to 152.degree.F., whereby under the conditions of use
the liquid is considered non-flammable. The paraffinic solvent also
is nontoxic. It possesses no objectionable odor and preferably is
odor-free, this being denoted by the term "low odor". Consonant
with its low dielectric constant and high resistivity, the liquid
carrier is non-polar. The liquid carrier has a low viscosity for
the purpose of permitting rapid migration therethrough of
non-dissolved particles and moieties which are to be attracted in
large number to the electrostatically charged image which is to be
developed. Such viscosity is between 0.5 and 2.5 centipoises at
room temperature. The petroleum fraction also is inexpensive.
Examples of petroleum fraction non-polar organic liquid carriers
having such physical characteristics are Shell Sol 71, manufactured
by Shell Oil Company; Isopar H, Isopar K and Isopar L, manufactured
by Humble Oil and Refining Company; Amsco OMS, Amsco 460 Solvent
and Amsco Odorless Insecticide Base, manufactured by American
Mineral Spirits Company; and odorless kerosene. All of the
foregoing are low odor paraffinic solvents. The dielectric constant
of Shell Sol 71 is 2.06 at room temperatures. The other solvents
have dielectric constants of the same order of magnitude. Other
physical characteristics of Shell Sol 71, Isopar H, Isopar K,
Isopar L, Amsco OMS, Amsco 460 Solvent and Amsco Odorless
Insecticide Base which fingerprint these solvents and denote the
presence of several of the above listed attributes are set forth
below:
Distillation Flash Pt. IBP* Dry End .degree.F. K.B. Aniline Sp.Gr.
.degree.F. Pt..degree.F. TCC No. Pt..degree.F.
60.degree./60.degree.F.
__________________________________________________________________________
Shell Sol 71 345 398 121 26.5 183 0.7563 Isopar H 350 371 123 26.9
183 0.7571 Isopar K 349 383 126 26.5 185 0.7587 Isopar L 372 406
144 -- 187 0.7674 Amsco OMS 352 386 125 27.0 184.5 0.7608 Amsco 460
Solvent 375 456 150 34.5 146.5 0.8108 Amsco Odorless Insecticide
Base 375 482 152 26.5 175.0 0.7711
__________________________________________________________________________
*Initial Boiling Point ASTM D-1078
The nub of the invention consists in the use with the solvent
system of a complex molecule having the polymeric moieties
mentioned above. Hence, the liquid toner is basically a latex
toner, which is to say, a toner that looks like a natural latex in
that it constitutes a liquid continuous phase having the desired
attributes for use in a patterned deposition system, together with
a dispersed phase which is an amphipathic polymer. The term "latex"
as used herein refers to a colloidal suspension of a synthetic
polymer in any liquid, for instance, as prepared by emulsion or
suspension polymerization. An "amphipathic" substance is one that
has an affinity for two different materials, for instance, oil or
water, or two different phases, so that one polymeric moiety of the
amphipathic polymer, which is the foregoing complex molecule, will
be solvated by the phase for which it has an affinity, which, in
this instance, is the solvent system, and another polymeric moiety
will not be solvated by this same phase, that is to say, will be
insoluble in this phase, so that the phenomenon is created when the
amphipathic polymer is contained in the solvent system of at least
one moiety of the polymer being solvated by the solvent system and
at least one moiety being non-solvated by the solvent system. The
amphipathic polymer combines in one complex molecule the fixing
agent, which is one or more of the moieties, the dispersing agent,
which is one or more of the moieties, and optionally, a color
agent, which is one or more of the moieties. This complex molecule,
i.e., amphipathic polymer, by virtue of the fact that it is a
molecule rather than a composition including a mixture of pigment
particles, creates a narrow range of size distribution of the
nonsolvated particles which ultimately are deposited on a
substrate, e.g., a copy sheet, as by electrostatographic
development, to create a patterned deposition. Desirably the
particle size distribution of the non-solvated particles in the
liquid toner of the invention is within two orders of magnitude and
preferably is within about one order of magnitude. The foregoing
ranges are what is denoted by the term "mono-dispersed".
The liquid toner, which is to say the latex system of the present
invention, is created generally as follows. Firstly, the solvent
system is chosen, for example, a non-polar solvent such as a
petroleum fraction like the ones mentioned above, although as
previously observed, other solvents could be used, e.g., polar
solvents such as water.
It is appropriate to mention at this point that patterned
depositions utilizing electrostatic phenomena, e.g.,
electrophoresis, do not necessarily involve the use of non-polar
solvent systems. Thus an electrostatic method using water as the
carrier system in electrostatography is shown in U.S. Letters Pat.
No. 3,425,829, issued Feb. 4, 1969. Other suitable solvent system,
by way of example, i.e., solvent systems other than petroleum
fractions and water, include alcohols, e.g., those having 1 to 6
carbon atoms, such as ethylene glycol; ethers, including ethyl
isobutyl ether, methyl isopropyl ether, the (C.sub.1 -C.sub.4)
alkyl mono ethers of ethylene glycol, and dioxane; ketones,
including acetone, methyl ethyl ketone, methyl isopropyl ketone,
and ethyl isobutyl ketones; esters, including ethyl acetate, amyl
acetate, butyl propionate, and the acetates of the mono- (C.sub.1
-C.sub.4)- alkyl ethers of ethylene glycol; and halogenated
hydrocarbons, such as chloroform, ethylene dichloride, monochloro
benzene and certain Freons.
After selection of the solvent system a polymeric backbone molecule
is chosen, which is solvated by the selected solvent system, i.e.,
which is fully soluble to the limit of its solubility. Next a graft
or block polymerization or copolymerization is carried out in such
a manner, hereinafter described, that non-solvated polymeric
chains, which is to say, polymeric chains which are not solvated by
the chosen solvent system, are created in the solvent system and
are chemically joined with, i.e., to, the solvated polymeric
backbone molecule. For the purpose of the present invention, the
mechanism by which the chains are created and chemically joined is
not of critical importance. For example, the chains first can be
formed and then grafted onto the polymeric backbone molecule or a
molecule of a grafting monomer can be first reacted with the
polymeric backbone molecule and subsequently this first monomer can
be polymerized with the other grafting monomers present in the
solvent system.
The non-solvated polymeric moiety, i.e., fraction or chains,
originates as a monomer which usually and preferably is solvated by
the solvent system for convenience in carrying out the reaction and
to minimize the time required for the reaction and also to
eliminate the need for solublizers or multi-solvent systems.
However, as the reaction for the formation of the chains proceeds
the addition to the backbone polymer, which is to say, the newly
formed chains, become progressively non-solvated and eventually
becomes a non-solvated moiety (portion) which constitutes a
dispersed phase, this, despite the fact that the polymeric backbone
still is solvated by the solvent system. It is interesting to
observe that the reaction as it takes place initially causes a
transformation of the clear solution of the solvated backbone
polymer and of the solvated monomer first into a slightly hazy
stage and then becomes more turbid as the minutes pass until
ultimately a latex is formed.
It is also possible to use a reverse process in which a
non-solvated polymeric backbone is partially solvated by graft or
block polymerization.
As mentioned previously, the largest present-day commercial use for
liquid toners is in electrostatography such as is used in the
so-called "liquid" xerographic copying machines. The solvent system
used in liquid toners for such purpose is usually a petroleum
fraction such as described heretofore and, hence, in detailing
various process steps in the manufacture of the complex molecule
this particular solvent system will be employed, although it is
understood that the invention is not limited thereto and can employ
any solvent system whatsoever.
Assuming, then, that the solvent system is a petroleum fraction, a
polymeric backbone material is selected which is solvated by such
petroleum fraction. A popularly employed petroleum fraction is
odorless mineral spirits (hereinafter OMS). There are many
polymeric materials which are solvated by OMS. These include, e.g.,
polymeric materials derived from natural sources such as crepe
rubber; refined oxidized linseed oil and degraded rubber, and
synthetic polymers such as alkyd resins; polyisobutylene;
polybutadiene; polyisoprene; polyisobornyl methacrylate; acrylic
polymers of long chain esters of acrylic or methacrylic acid such
as stearyl, lauryl, osodecyl, octyl, 2-ethylhexyl and hexyl; butyl
esters of acrylic or methacrylic acids; polymeric vinyl esters of
long chain acids such as vinyl stearate, vinyl laurate, vinyl
palmitate and vinyl myristate; polymeric vinyl alkyl ethers,
including poly (vinyl ethyl ether) sold under the trademark
Bakelite EDBM by Union Carbide Corp., poly (vinyl isopropyl ether),
poly (vinyl isobutyl ether) and poly (vinyl n-butyl ether). As can
be seen from the examples given, the polymers chosen have a
structure similar to that of the solvent which is going to solvate
thme, i.e., the polymers and the solvent system have a similar
degree of polarity. As long as this similar polarity is maintained,
copolymers, e.g., lauryl methacrylate-butyl acrylate, t-octyl
methacrylate-butyl methacrylate, lauryl methacrylate-glycidyl
methacrylate, 2-ethyl hexyl acrylate-acrylic acid, isodecyl
methacrylate-diethylaminoethyl methacrylate and vinyl
toluene-butadiene; terpolymers, e.g., lauryl methacrylate-isodecyl
methacrylatemethyl methacrylate, stearyl methacrylate-cyclohexyl
acrylatemethacrylic acid, octyl acrylate-crotonic acid-dodecyl
methacrylate, glycidyl methacrylate-stearyl methacrylate-lauryl
methacrylate, lauryl methacrylate-octyl methacrylate-glycidyl
methacrylate and isodecyl methacrylate-stearyl methacrylateacrylic
acid; and tetrapolymers, e.g., N-vinyl pyrrolidone-butyl
acrylate-lauryl methacrylate-stearyl methacrylate and acrylic
acid-stearyl acrylate-methyl methacrylate-isodecyl acrylate, may be
used, as well as block and graft copolymers, block and graft
terpolymers, block and graft tetrapolymers and multi-type
monomer/polymers in general as the backbone structure.
If desired, the backbone structure with or without added polymers
chains can be created in a solvent other than that in which it is
ultimately to be used, i.e., in a solvent other than the solvent
system of the liquid toner. The original solvent in which the
backbone structure with or without added chains is created can
either be extracted or it can be part of a multi-solvent system in
the liquid toner. Many monomers which it might be desirable to
employ in building a backbone structure are not sufficiently
solvated by OMS or other solvent system of the liquid toner to
enable the polymerization of the desired structure to be effected
in OMS. In such a case, a copolymerization utilizing such
insufficiently solvated monomers may be carried out in a solvent of
higher K.B. number with another monomer which is solvated by OMS,
as long as the resultant copolymer contains enough of the second
monomer so that the backbone can be solvated by OMS. Such a
copolymerization, for example, could be carried out in benzene, the
resulting copolymer precipitated by the addition of methanol, freed
from solvent, and dissolved in OMS to function as the backbone
during the subsequent graft or block polymerization or graft or
block copolymerization.
The discussion above of synthetic polymeric materials suitable for
use as the backbone, also often hereinafter sometimes referred to
as the "precursor", in an OMS-based electrostatographic toner
system is not limited to addition polymers; synthetic condensation
polymers can also serve as the backbone or precursor in this system
as long as they can be solvated by the chosen solvent medium, e.g.,
the self-condensation polymer of 12-hydroxystearic acid.
Inasmuch as the present invention is not limited to any particular
solvent system, there is no limitation on the monomers that can be
used to fabricate the polymeric constituents of the system. In the
particular system being discussed, however, that based on OMS, the
following list of backbone polymers is exemplificative but not
exclusive:
a. the homopolymers of the C.sub.4 -C.sub.22 esters of acrylic and
methacrylic acid, such as polyhexyl methacrylate and acrylate,
polyisodecyl methacrylate and acrylate, polylauryl methacrylate and
acrylate, polytetradecyl methacrylate and acrylate, and polystearyl
methacrylate and acrylate, all in the molecular weight range of
about 10.sup.3 to about 10.sup.6, but preferably not smaller than
10.sup.4 ;
b. copolymers, with each other, of any of the above monomers used
to form the nomopolymers under (a), and also with the methyl,
ethyl, isopropyl and propyl esters of acrylic and methacrylic acid,
provided that the ratios of non-solvated to solvated monomers are
kept in a proportion such as to insure solvation of the resulting
copolymer by OMS:
c. copolymers of the above mentioned methacrylic and acrylic acid
esters with monomers containing other functional groups as, for
example, acrylic acid, methacrylic acid, crotonic acid, maleic
acid, atropic acid, fumaric acid, itaconic acid, citraconic acid,
acrylic anhydride, methacrylic anhydride, maleic anhydride,
acryloyl chloride, methacryloyl chloride, acrylonitrile,
methacrylonitrile, acrylamide and derivatives thereof,
methacrylamide and derivatives thereof, hydroxyethyl methacrylate
and acrylate, hydroxypropyl methacrylate and acrylate,
dimethylaminomethyl methacrylate and acrylate, dimethylaminoethyl
methacrylate and acrylate, dimethylaminoethyl methacrylate and
acrylate, diethylaminoethyl methacrylate and acrylate,
t-butylaminoethyl methacrylate and acrylate, allyl alcohol and
derivatives thereof, cinnamic acid and derivatives thereof, styrene
and derivatives thereof, methallyl alcohol and derivatives thereof,
propargyl alcohol and derivatives thereof, indene and derivatives
thereof, norbornene and derivatives thereof, vinyl ethers, vinyl
esters and other vinyl derivatives, glycidyl methacrylate and
acrylate, mono- and dimethyl maleate, mono- and dimethyl fumarate,
mono- and diethyl maleate and mono- and diethyl fumarate;
d. homopolymers of olefins such as polybutadiene, polyisoprene,
polyisobutylene, and copolymers of these monomers with any of the
monomers listed above consistent with the solvation limitation as
described under (b);
e. terpolymers and tetrapolymers of the above;
f. polycarbonates, polyamides, polyurethanes and epoxies.
With the backbone, i.e., precursor, chosen, there are added on to
this backbone polymeric chains of a different degree of polarity
from that of the solvent so that these chains, although grafted on
or block polymerized to the solvated backbone, will themselves be
non-solvated by the solvent system and, hence, form a dispersed
phase. This addition of such chains is carried out via either a
block or graft polymerization as just noted. Suitable monomers
which form polymers that are too polar to be solvated by the GMS
solvent medium are vinyl acetate, methyl acrylate and methacrylate,
ethyl acrylate and methacrylate, propyl acrylate and methacrylate,
isopropyl acrylate and methacrylate, hydroxy ethyl acrylate and
methacrylate, hydroxy propyl acrylate and methacrylate,
acrylonitrile, methacrylonitrile, acrylamide, methacrylamide,
acrylic acid and anhydride, methacrylic acid and anhydride, mono
methyl maleate, mono methyl fumarate, mono ethyl maleate, mono
ethyl fumarate, styrene, vinyl toluene, maleic acid and anhydride
and crotonic acid and its anhydride. The invention is not limited
to homopolymers in this further polymerization procedure;
copolymers and terpolymers or polymers of greater degrees of
complexity, but of the proper polarity, could be joined to the
chosen solvated backbone structure to form the latex.
When a grafting procedure is chosen for the latex forming step, and
there are no ethylenic or other unsaturated bonds available in the
backbone for accepting the graft, polymeric chains can be grafted
onto a saturated backbone, nevertheless, through the use of
activating methods known to those skilled in the art. This method,
however, although useful, leads to a haphazard activation by the
initiator employed of a site or sites in the backbone molecule
which subsequently serve to initiate the polymerization of the
grafting monomer. A preferred method, rather than haphazard
activation, is to construct the backbone molecule in such a way as
to produce ethylenically unsaturated double bonds or other
unsaturated bonds containing pendant moieties to serve as sites to
be activated by the initiator for in situ graft polymerization.
Thus, there may be employed an OMS solvated backbone molecule
consisting of a copolymer of stearyl methacrylate-glycidyl
methacrylate of the proper (27:1) monomer ratio and molecular
weight, e.g., 10,000 to 150,000. Methacrylic acid can be reacted
with this polymer in the presence of a polymerization inhibitor to
provide ethylenically unsaturated double bond containing sites
through an esterification reaction for activation and subsequent in
situ polymerization or copolymerization. In such a manner,
precursors for a graft polymerization or copolymerization can be
made. The term "precursor" as used herein denotes a backbone such
as described, as well as a treated (activated) backbone, which is
to be used as the base for reaction to form a latex.
Many different reactions can be utilized to introduce these
ethylenically unsaturated double bond containing pendant groups
into the precursor. If the comonomer of the backbone chain is
called Monomer 1 (such "comonomer" is at least one of two monomers
which forms the backbone chain and which is present in a minority
proportion by weight and which includes an unsaturated bond before
copolymerization, said bond having been reacted in the formation of
the copolymer but still contains a reactive group) and the
precursor monomer is called Monomer 2 (the precursor is
specifically selected to be reactive with the reactive group of the
comonomer), the following are illustrative examples:
Monomer 1 Monomer 2 ______________________________________ Acrylic
acid Glycidyl methacrylate Methacrylic acid or acrylate Maleic acid
Fumaric acid Atropic acid Allylamine Vinyl amine Hydroxyethyl
methacrylate and acrylate Hydroxypropyl methacrylate Acryloyl or
methacryloyl and acrylate chloride Acrylamide Methacrylamide Allyl
alcohol Allylamine Vinyl amine Acrylic acid Vinyl pyridines
Methacrylic acid Glycidyl methacrylate Maleic acid Vinylamine
Crotonic acid Allylamine Alkyl hydrogen maleates Dialkylaminoalkyl
methacryl- Alkyl hydrogen fumarates ates and acrylates Allylamine
Vinyl isocyanate Vinylamine Methacrylyl acetone Cyanomethylacrylate
Vinylamine Allylamine Allylamine Vinyl .beta.-chloroethyl-
Vinylamine sulphone Allyl alcohol Hydroxyalkyl methacrylates
Glycidyl methacrylate Methacrylic anhydride Vinylamine Acrylic
anhydride Allylamine Maleic anhydride Hydroxyalkyl methacrylates
Allyl alcohol Vinyl sulphonic acid N-hydroxymethyl methacryl-
amides Vinyl phosphoric acid Alkoxymethyl methacrylamides
______________________________________
The reverse reactions can also be utilized, i.e., Monomer 2 can be
copolymerized into the backbone and subsequently condensed with
Monomer 1 to create the precursor.
With the precursor formed, the latex is prepared by carrying out,
in a liquid system wherein the precursor or additional fraction
(moiety) is fully solvated and the other fraction (moiety) not
fully solvated, the polymerization of the monomer or comonomers
chosen for the additional fraction which preferably is the
dispersed phase in the presence of and in conjunction with the
precursor. In the preferred form of the invention, the monomer or
monomers chosen polymerize to a material which is nonsolvated by
the solvent system employed. For example, in an OMS-based system
using the stearyl methacrylate-glycidyl methacrylate-methacrylic
acid precursor, typical useful monomers for the additional fraction
include methyl methacrylate, methylacrylate, ethyl methacrylate,
ethyl acrylate, isopropyl methacrylate, styrene, vinyl acetate,
vinyl chloride, vinyl toluene, acrylonitrile and methacrylonitrile,
as homopolymers or copolymers, or any one or more of the above with
maleic anhydride, crotonic acid, acrylic acid, mono methyl maleate,
mono methyl fumarate, mono ethyl maleate, mono ethyl fumarate,
methacrylic acid, dimethylaminomethyl methacrylate, or terpolymers
or tetrapolymers of any of the foregoing. When this polymerization
is carried out, part of the monomer polymerizes with the precursor
molecule (solvated backbone) to form a graft copolymer which is one
form of complex tailored molecule embodying the invention, and this
serves to stabilize any disperse polymer particles which are not
grafted.
It will be appreciated that the dispersed phase which, in
principle, is the non-solvated moiety of the complex amphipathic
resin molecule, also may include dispersed non-grafted non-solvated
polymer particles. Although the latter are not particularly
desirable by virtue of their non-solvation, they are aggregatable
and, moreover, are able to behave electrophoretically so that they
are capable of being selectively attracted to differentially
electrostatically charged areas, whereby to form a graphic
representation by electrostatography.
With a latex of the foregoing character constituting the complex
tailored amphipathic resin molecule as thus far described, the
fixative (substrate bonding) and dispersant functions are combined
into a single molecule which will behave properly in an
electrostatographic system. That is to say, this molecule, of which
there are a great number in any particular liquid toner, will be
capable of charge direction and fixation and yet will not, because
of the solvated moiety, tend to settle so that it has a "built-in"
dispersing ability. Moreover, because, in effect, the molecule
includes both an equivalent of a fixative agent and an equivalent
of a dispersing agent in a single molecule, the two will be
consumed (depleted) at fixed rates, depending upon their
proportions in the molecule. Hence, when they are to be
replenished, they do not have to be replenished at different rates
to bring back the original optimum conditions, nor will there be a
deviation from original optimum conditions and proportions because
of a differential rate of depletion. Thereby, at least as to the
dispersant and fixative functions, a substantial improvement over
the prior art has been obtained.
Of course, this complex tailored molecule, together with the
solvent system, is not capable, by itself, of use as a liquid
toner, that is to say, to form a visible selective deposition on a
differentially electrostatically charged substrate. It is
additionally necessary for the liquid toner to contain a color
ranging from black to white through all of the various hues.
Phrased differently, it is necessary to color the suspended latex
particles so that when they are preferentially attracted to
differentially electrostatically charged regions of a substrate and
deposited thereon, the film left by the deposit ("film" is here
used in a sense not of a broad continuous layer but, rather, of a
coating which may cover only a physically small portion of an area
and may have any type of peripheral configuration depending upon
the image that is to be produced) will likewise be colored so that
they can be readily visible and also, if desired, so that a
specific color can be created.
One way of imparting the color is by using either pigments or dyes
added to the latex and physically dispersing them therein as by
ball milling or high shear mixing.
The pigment employed can be any one of the many now known to the
art in connection with liquid electrostatographic developers. As is
well known, these pigments essentially constitute very fine solid
particles the size of which is in the submicron range and which are
opaque en masse. They are insoluble in the liquid system. So many
different kinds and species of pigments are known that only typical
representative examples will be mentioned. These are: powdered
metals, e.g., powdered aluminum; powdered metal oxides, e.g.,
powdered magnetic iron oxide, e.g., powdered metal salts, e.g.,
powdered cadmium selenide (CdSe), powdered lead iodide (PbI.sub.2),
powdered lead chromate (PbCrO.sub.4); Acetamine Black CBS
(Dupont)*; Nigrosine Base No. 424 (Dupont) (50415 B) **; Hansa
Yellow G (General Aniline) (11680); Spirit Nigrosine SSB (National
Aniline) (50415); Rubanox Red CP-1495 (Sherwin-Williams) (15630);
Raven 11 (Columbian Carbon) carbon black aggregates with a particle
size of about 25 .mu.; and chrome green.
When the dispersed phasse is colored by pigment, such preferably
are non-reactive with the amphipathic polymer. It is believed that
pigment particles are held to the non-solvated latex moiety by
second order forces only, i.e., are thus held to the dispersed
phase of the complex amphipathic resin molecule. It has been
observed that graphic representations, e.g., electrostatographic
images, formed by the use of the system above described, that is to
say, with the use of liquid toners of the invention, are
smear-resistant to a very substantial degree and considerably
superior in this and other respects (e.g., clarity of background
and easier replenishment) to liquid toners commercially available.
However, they are not smear-proof. Nevertheless, liquid toners
embodying pigment particles held in the foregoing manner have a
definite commercial utility. For instance, they can be used as
liquid toners to lay down a phosphor layer in color television
tubes.
In a preferred form of the invention, the images formed by the
liquid toner are smear-proof and this is accomplished, as will
later be pointed out, by employing pigments or dyes which are
chemically bonded to the latex, that is to say, which become
chemically bonded to and are part of the complex molecule. The
chemical bonding can be to the precursor before the graft or block
polymerization of the added chains or it can be to the chains added
by graft or block polymerization.
As to dyes, as distinguished from pigments, these may be used to
color the specific complex amphipathic resin polymer molecule and
specifically to color the dispersed non-solvated phase thereof be
being held thereto by second order or surface adsorption forces or
the dyes can be chemically reacted with the complex tailored
molecule, either after its formation, or to the precursor, or to
the chain as it is being or after it has been grafted or block
polymerized.
The dyes are incorporated in a liquid toner by second order or
surface adsorption forces, as by heating the latex and dye together
for a sufficient time, for example, one to twelve hours. One type
of example of such dyes is dispersed dyes for dyeing polyester and
copolymers of acrylonitrile and vinyl chloride where the dispersed
phase is a polyester or a copolymer of acrylonitrile and vinyl
chloride. Such dyes include: Latyl Orange 3R (Dupont ) (C.I.
Disperse Orange 26); Calcosperse Yellow GL (American Cyanamid)
(C.I. Disperse Yellow 57); Calcosperse Blue B (American Cyanamid)
(C.I. Disperse Blue 77); Foron Blue BGL (Sandoz Inc.) (C.I.
Disperse Blue 73); Latyl Brown MS (Dupont) (C.I. Disperse Brown 2);
and Latyl Violet BN (Dupont) (C.I. Violet 27). Other examples of
such dyes are basic dyes for polyacrylics, where the dispersed
phase is a polyacrylic. Typical of such dyes are: Sevron Blue BGL
(Dupont) (C.I. Basic Blue 35); Sevron Brilliant Red 3B (Dupont)
(C.I. Basic Violet 15); Deorlene Brilliant Red 3B (Ciba) (C.I.
Basic Red 26); Calcozine Arcylic Blue G (American Cyanamid) (C.I.
Basic Blue 38); Astrazon Yellow Brown GGL (Farbenfabriken Bayer)
(C.I. Basic Orange 30); and Astrazon Red 5BL (Farbenfabriken Bayer)
(C.I. Basic Red 24).
The use of a dye held by second order or surface adsorption forces
is suitable for many purposes because it has a good degree of
smear-resistance and is superior to present-day commercially
available liquid toners in such respect. However, as in the case of
similarly held pigments, the deposit on a surface is not
smear-proof. But such a dye-colored liquid toner has an excellent
commercial useage where the areas upon which deposits are made are
not exposed to abrasion, i.e., actions which cannot result in
smearing, e.g., a phorphor deposit on the inside face of a color
television tube, and, indeed, it is acceptable for graphic copy
work.
Nevertheless, a better approach and one which is preferred in a
more sophisticated form of the present invention is to create a
dispersed (non-solvated) phase of a copolymer containing reactive
groups which will react with reactive groups of a chromophoric
nature, for example, a dispersed phase of a copolymer containing
basic groups which can be reacted with acid dyes. An example of a
dispersed phase of a latex which can be used in the foregoing
manner is a terpolymer of acrylonitrile, 2-methyl-5-vinyl pyridine
and vinyl acetate. Such terpolymer can be reaction dyed with dyes
containing acid groups of which examples are: Pontacyl Brilliant
Blue A (Dupont) (C.I. Acid Blue 7); Calcocid Brilliant Blue FFR
(American Cyanamid) (C.I. Acid Blue 104); Femazo Brown N (General
Aniline) (C.I. Acid Brown 14); Crocein Scarlet N (Dupont) (C.I. Red
73); Oxanal Yellow I (Ciba) (C.I. Acid Yellow 63); and Benzyl Black
4BN (Ciba) (C.I. Black 26A).
Such a complex tailored molecule is tri-functional. It contains not
only the dispersant and fixative functions but also the coloring
functions, whereby the single sophisticated molecule has a fixed
depletion rate for all three of these functions and a liquid toner
containing this type of molecule can be replenished with a toner
containing identical molecules. Moreover, the liquid toner has an
essentially mono-dispersed phase, i.e., a small range of variation
of particle size. Thereby, the operating bath made up of this toner
will always operate with maximum efficiency.
It will be appreciated that a bath with a liquid solvent system and
the fixative/dispersant/color functions in a single molecule omits
only one function, to wit, that of charge direction. Accordingly,
the constitution of the bath is now far simpler; its operation is
far more efficient; and its replenishment is much easier.
Furthermore, because of the mono-dispersed phase, the toner yields
excellent resolution.
An alternate method of creating the more sophisticated complex
tri-functional amphipathic resin molecule which embodies the
aforesaid three functions of fixing, dispersing and coloring is to
create a dispersed phase of a copolymer containing acid groups
which then are reacted with basic dyes (instead of with the
aforesaid acid dyes). An example of a dispersed phase of such a
latex is a copolymer of vinyl acetate-maleic acid. This is dyeable
with dyes containing basic groups of which examples are: Magneta
(C.I. Solvent Red 41, C.I. No. 42510B), Crystal Violet (C.I.
Solvent Violet 9, C.I. No. 42555B), Bismarck Brown (C.I. Solvent
Brown 12, C.I. No. 21010B), Victoria Blue BA (C.I. Solvent Blue 4,
C.I. No. 44045B), Victoria Blue R (C.I. Solvent Blue 6, C.I. No.
44040R), Victoria Blue 4R (C.I. Solvent Blue 2, C.I. No. 42563B),
Copying Black SK (C.I. No. 11975), Janus Green B (C.I. No. 11050),
Auramine 0 (C.I. Solvent Yellow 34, C.I. No. 41000B), Victoria
Green (C.I. Solvent Green 1, C.I. No. 42000B), and Rhodamine (C.I.
SOlvent Red 49, C.I. No. 45170B).
Still another method of creating a tri-functional complex tailored
amphipathic resin molecule pursuant to the invention by virtue of a
chemical reaction for bonding the color agent to the block or graft
modified precursor is to create a dispersed phase of a copolymer
containing electron acceptor groups, for example, maleic acid or
crotonic acid which are Lewis acids and which are then reacted with
color precursors that are well known in the art. An example of this
latter tri-functional sophisticated complex molecule is a
terpolymer of maleic anhydride-vinyl acetate-styrene (on a solvated
backbone) and reacted with a color precursor such for instance as
bis (p-dimethylaminophenyl)-benzotriazyl methane. A liquid toner
embodying the foregoing complex molecule will produce a deep blue
colored deposit.
Where the pigment or dye is reacted with the added groups in the
dispersed phase, the amount of pigment employed can fluctuate from
as low as 5 percent to a theoretical 100% of the calculated
stoichiometric amount. Nevertheless, it is preferred to have the
amount of dye or pigment thus incorporated vary between about 10
and 50 percent of the stoichiometric amount, with best results
having been obtained at about 25 percent of the stoichiometric
figure.
There is yet another way, in accordance with the present invention,
for coloring latexes, i.e., liquid toners. This is to color the
precursor iteslf, which is to say, the backbone that is the
solvated phase rather than to color the dispersed unsolvated phase.
Although there could be used for coloring the precursor some of the
methods recited above to color the dispersed phase by chemical
reaction or by second order bonds or surface adsorption or even by
chemical reactions of chromophores with the precursor, a highly
preferred method is to employ a dye which is copolymerized into the
precursor itself, that is to say, the solvated backbone, before the
backbone is grafted or block polymerized with the non-solvated
moieties (chains). An example of such a process is set forth below
(EXAMPLE VIII) along with many other examples of methods of
manufacturing the complex amphipathic resin molecule of the present
invention.
It should be observed, moreover, that, if desired, both the
dispersed phase and the solvated precursor can be dyed by any of
the manners above discussed in detail.
As thus far described, there has been provided a stable latex which
constitutes practically all of the necessary ingredients of a
liquid toner, these including the liquid solvent system with the
complex amphipathic resin molecule having solvated and non-solvated
moieties and which is tri-functional as to the fixative, dispersant
and colorant or includes a separate (non-reacted) color agent. It
still is, nevertheless, extremely desirable to include in the
liquid toner a charge director or directors, the same adding
greatly to the depth of color obtained in electrostatographic
development and aiding in contrast. Hence, pursuant to the present
invention there preferably is included in the liquid toner as a
component over and above the solvent system, the complex molecule
and a separate colorant, if one is not included as a moiety of the
complex molecule, a charge director in the proper concentration to
permit the liquid toner to function effectively for the particular
use intended. In electrostatographic development a charge director
present in a suitable concentration is to all intents and purposes
a necessity.
Inasmuch as the present invention is capable of functioning with a
wide variety of solvent systems ranging from non-polar to polar,
and since there are a wide variety of charge directors which are
known to the art, the present specification does not hereinbelow
set forth an all-inclusive list of such materials. Indeed, even
restricting the solvent to a petroleum fraction, specifically OMS,
it would not be practical within the confines of this specification
to list every one of the known charge directors.
The charge directors in a conventional liquid electrostatographic
toner serve several purposes. In general, they are adsorbed by the
pigment particles and seem to act as bridges between the "ultimate
particle size" particles leading to an agglomeration or partial
flocculation of these very tiny particles to form the aggregates
which ultimately are deposited on an electrostatically charged
substrate such as the patterned electrostatically charged image
area of an electrostatic latent image, or on the non-image area in
the case of a reverse toner. The charge directors also appear to
create a molecular environment about these aggregates which is
responsive either via electrostatic and/or polarization effects to
the influence of the electric field. They also are able to modify
the conductance of the continuous phase which facilitates the
action of the field of an electrostatic latent image to either
attract or repel the suspended aggregates.
In the liquid toner system of the present invention, since the
particles that have been created are virtually monodispersed and
remain this way because of the entropic repulsion of the polymeric
precursor chains, the charge directors present in the new system
probably have only the two-fold purpose of creating the correct
molecular environment around the particles and of modifying the
conductance of the continuous phase. In other words, they are not
useful nor do they need to be of any assistance in connection with
flocculation (aggregation).
The various charge directors which are conventionally employed in
the commercial and patented liquid electrostatographic toners for
the development of electrostatographic images in office copy
machines and the like, are useful in the unique toner of the
present invention. Examples thereof are:
Aerosol OT which is di-2-ethylhexyl sodium sulfosuccinate;
Aerosol TR which is di-tridecyl sodium sulfosuccinate;
the aluminum, chrominum, zinc and calcium salts of 3,
5-dialkylsalicylic acid, wherein the alkyl group is propyl,
isopropyl, butyl, isobutyl, tertiary butyl, amyl, isoamyl and other
alkyl groups up to C-18;
the aluminum, chromium, zinc and calcium salts of dialkyl
gamma-resorcylic acid, wherein the alkyl is as above;
the isopropylamine salt of dodecylbenzene sulfonic acid;
aluminum, vanadium and tin dresinates (the metal dresinates are
prepared by adding a solution of the metal sulfate to a solution of
the sodium salt of Dresinate 731 manufactured by Hercules Powder
Co.);
aluminum stearate;
cobalt, iron and manganese octoates;
OLOA 1200 which is a product of the Oronite Division of California
Chemical Co., the same being a partially imidized polyamine with
lubricating-oil-soluble polyisobutylene chains and free secondary
amines, its specifications are: gravity at 60.degree.F API 22.9,
specific 0.92, flash point by the Cleveland open cup method,
425.degree.F, viscosity at 210.degree.F, 400 SSU, color (ASTM
D-1500) L55D, nitrogen, percentage by weight 2.0, and alkalinity
value, (SM-205-15) 43;
soya bean lecithin;
an aluminum salt of 50-50 by weight mixture of the mono- and di- 2
ethylhexyl esters of phosphoric acid; and
Alkanol DOA which is a product of E. I. duPont de Nemours &
Co., Inc. This product is a viscous light amber colored liquid
composed 50 percent by weight of a terpolymer in kerosene. The
terpolymer consists of 50 percent by weight octadecenyl
methacrylate, 40 parts by weight styrene and 10 parts by weight
diethylaminoethyl methacrylate. The specific gravity of the product
at 77.degree.F is 0.888. Its acid number (milligrams KOH/gram of
sample) is 0.2. Its total monomer content is 15.5 percent maximum
by weight. Its basic nitrogen content is 0.40 percent .+-. 0.03
percent by weight. Its base number (equivalent to milligrams
KOH/gram of sample) is 13.8.
Where charge directors are used they preferably are soluble in the
liquid solvent system (aluminum stearate is the sole insoluble one)
and the charge director employed (more than one can be employed if
desired) is a material which when present in the latex, i.e.,
dissolved in the latex solvent system, will reduce the resistivity
of the latex solvent system from 10.sup.14 to no less than 2
.times. 10.sup.9 ohm cms. and desirabley between 10.sup.13 to
10.sup.10 ohm cms. and preferably between 2 .times. 10.sup.12 and
10.sup.11 ohm cms. It is pertinent to observe that toner
resistivity is not per se the sole criterion of acceptable prints.
Frequently where two different charge directors adjust a toner
resistivity to the same value the prints obtained using the two
different toners will not be equally acceptable.
The amounts of the different solid constituents of the liquid toner
(amphipathic molecule, optimally a coloring material, and a charge
director) are capable of extremely wide variation, indeed, so wide
that assigning specific figures thereto of the extreme ranges which
function in accordance with the invention is largely meaningless.
For example, the amounts will vary with the type of machine,
climate, machine sseeds, types of paper and experience of the
operator, to mention but a few. Also, particularly in the case of
the coloring material, the amounts will vary with the intensity of
the dye or pigment and the desired degree of intensity of the
image. Generally speaking, moreover, the amounts of the individual
solids compounds will increase or decrease together, although not
in strict proportion. Bearing all of this in mind and in order to
assist workers in the art in the preparation of toners embodying
the present invention, the following represent approximately
maximum and minimum amounts of the various solids constituents per
liter of liquid toner.
For the complex amphipathic molecule where the same includes a dye
or pigment either chemically reacted therewith or bonded thereto or
affiliated therewith by surface adsorption forces from about 0.03
g. to about 30 g.
For the complex amphipathic molecule where the same does not
include a chromophore reacted or associated therewith from about
0.03 g. to about 30 g.
For the color agent where the same is not reacted or bound to the
complex amphipathic molecule from about 0.03 g. to about 30 g.
For the charge director from about 1 .times. 10.sup.-.sup.6 g. to
about 10 g.
Examples of different specific embodiments of the invention
follow:
The first nine examples are examples of precursors, i.e., examples
of the formation of the backbone, that is to say, the spine, of the
amphipathic molecule with which a subsequent reaction will later be
described in further examples which deal with the formation of the
latices from the precursors and toners from the latices.
EXAMPLE I
In a clean dry 8 oz. glass jar is placed 100 gs. of
2-ethylhexyl-acrylate and 1 g. of AZBN (azobisisobutyronitrile), a
polymerization initiator. The jar is placed in a water bath
maintained at 75.degree. .+-. 2.degree.C. After about 30 minutes an
exothermic polymerization takes place. The temperature reaches a
maximum of 120.degree.C. in about 5 minutes after the start of the
exotherm. After it cools down to 90.degree.C. the jar is removed
from the water bath loosely covered and placed in a hot air oven at
90.degree.C. overnight to complete the polymerization. The product
is a nearly water-white heavy syrup.
EXAMPLE II
Four hundred grams of petroleum ether (b.p.90.degree.-120.degree.C)
is placed in a 1 liter reaction flask equipped with a stirrer, a
thermometer, a reflux condenser, and a dropping funnel and heated
to a gentle reflux at atmospheric pressure. A solution of 1.2 g.
AZBN in 200 g. of 2-ethylhexyl-acrylate and 6 g. of glycidyl
methacrylate is placed in the dropping funnel and allowed to drip
into the reflux stream at such a rate that the addition takes 3
hrs. The mixture is refluxed at atmospheric pressure for an
additional 2 hrs. at which time 4 g. of acrylic acid, 0.14 g. of 2,
6-di-tertiary butylphenol and 1 g. of lauryl dimethyl amine is
added. The mixture is refluxed at atmospheric pressure for 12 more
hours uner a nitrogen blanket to esterify ca. 25 percent of the
glycidyl rings of the copolymer. The product is a straw-colored
somewhat viscous liquid.
EXAMPLE III
In a 500 ml. resin reactor equipped with a stirrer, a thermometer,
a reflux condenser and a dropping funnel is placed 250 gms. of
Isopar E. The solvent is heated to 93.degree. .+-. 1.degree.C. and
250 gs. of 2-ethylhexyl acrylate containing 1.5 gs. of AZBN is
added dropwise to the hot solvent over a period of 3 hrs. The
mixture is maintained at 93.degree. .+-. 1.degree.C. for 3
additional hours to complete polymerization. All reactions take
place in the reactor at atmospheric pressure. The product is a
slightly viscous straw-colored liquid.
EXAMPLE IV
In a 1 liter reaction flask equipped with a stirrer, a thermometer
and a reflux condenser is placed 400 gs. of petroleum ether
(b.p.90.degree.-120.degree.C.) and the same is then heated at
atmospheric pressure to a moderate rate of reflux. A solution is
made of 194 gs. lauryl methacrylate, 6.0 gs. of glycidyl
methacrylate and 3.0 gs. of benzoyl peroxide paste (60 percent by
wt. in dioctyl phthalate) and placed in a 250 ml. dropping funnel
attached to the reflux condenser. The monomer mixture is allowed to
drip into the refluxing solvent at such a rate that it requires 3
hrs. for the total amount to be added. After refluxing 40 minutes
at atmospheric pressure beyond the final addition of monomer, 0.5
gs. of lauryl dimethyl amine is added and the refluxing is
continued at atmospheric pressure for another hour. Then 0.1 g.
hydroquinone and 3.0 gs. methacrylic acid are added and refluxing
continued under a nitrogen blanket until ca. 52 percent
esterification of the glycidyl groups is effected (about 16 hours).
The resulting product is a slightly viscous straw-colored
liquid.
EXAMPLE V
EXAMPLE IV is repeated except that the final refluxing is concluded
when ca. 25 percent esterification of the glycidyl groups has been
effected.
EXAMPLE VI
In a 5 liter jacketed glass reactor open to the atmosphere and
equipped with a stirrer, a thermometer, a nitrogen bubbler and a
reflux condenser is placed 2400 gs. of Isopar G. The solvent is
heated to 110.degree. .+-. 1.degree.C. by circulating hot
triethylene glycol through the jacket. The temperature of the
glycol is controlled by a proportional heating unit with its
temperature sensor in a reservoir of the heating fluid from which
the hot liquid is pumped to the reactor and subsequently returned
to the reservoir for further heating. A three-way valve arrangement
allows the glycol heating system to be isolated from the jacketed
reactor so that cold water can be immediately supplied to the
jacketed reactor to keep the temperature constant during the
polymerization exotherm when necessary. When the solvent reaches
the foregoing temperature, a mixture of 1035.7 gs. isodecyl
methacrylate, 36.0 gs. glycidyl methacrylate and 18.0 gs. Luperco
ANS-50 (a paste consisting of 50 percent benzoyl peroxide by weight
in dioctyl phthalate) is added at a constant rate over a 3 hr.
period through a dropping funnel attached to the condenser. After
all of the monomer solution has been added, the reaction mixture is
held at 110.degree. .+-. 1.degree.C. for another 30 min. Then 3.0
gs. lauryl dimethyl amine is added and the reaction mixture again
held at said temperature for 1 hr. At this point 0.6 gs.
hydroquinone is added and the nitrogen bubbler is started to
provide a nitrogen blanket during the esterification. Then 18.0 gs.
of methacrylic acid is added and the reaction temperature is
maintained until an acid drop indicates that 25 percent of the
glycidyl rings have been esterified (ca. 8 hrs.). The product that
results is a slightly viscous straw-colored liquid.
EXAMPLE VII
Using the same apparatus as described in EXAMPLE VI, 1440 gs. of
Isopar G is warned to 110.degree. .+-. 1.degree.C. To this hot
solvent, a solution of 1278.6 gs. stearyl methacrylate, 32.4 gs.
glycidyl methacrylate, and 16.2 gs. Luperco ANS 50 in 720 gs. of
Isopar G is added through a dropping funnel attached to the
condenser over a 3 hr. period, the temperature being maintained at
110.degree. .+-. 1.degree.C. After all of the monomer solution has
been added, the reaction mixture is held at 110.degree. .+-.
1.degree.C. for another 40 mins. Then 2.8 gs. lauryl dimethyl amine
is added and the reaction mixture again held at said temperature
for 1 hour. At this point 0.54 gs. hydroquinone is added and the
nitrogen bubbler is started to provide a nitrogen blanket during
the esterification. Then 16.2 gs. methacrylic acid is added and the
reaction temperature is maintained until an acid drop indicates tha
t24 percent of the glycidyl rings have been esterified (ca. 7
hrs.). The product is a slightly viscous straw-colored liquid.
EXAMPLE VIII
In a 500 ml. 3-neck round-bottom reaction flask open to the
atmosphere and equipped with a stirrer, a thermometer, a
thermocouple for a thermoregulator and a reflux condenser, is
placed 197.8 g. Isopar G. The solvent is warmed to 110.degree. .+-.
1.degree.C. with stirring. A mixture of 96.0 g. lauryl
methacrylate, 3.0 g. glycidyl methacrylate, 0.74 gs. benzoyl
peroxide (99%), 50 mls. of benzene and 5.0 gs. of
p-phenylazoacrylanilide is prepared by stirring on a magnetic mixer
for 30 minutes at room temperature. Most but not all of the
p-phenylazoacrylanilide dissolves. This mixture is added in 5 ml.
increments at 5 min. intervals over a period of 3 hrs. to the
solvent in the flask. The mixture is kept well stirred so that each
addition will be indentical in composition. After the last
addition, the mixture is allowed to react at 110.degree. .+-.
1.degree.C. for 45 minutes and then 0.25 gs. lauryl dimethyl amine
is added. After one more hour of reaction time, 0.05 g.
hydroquinone is added and a nitrogen sparge is started. Then 1.49
g. methacrylic acid is added and the temperature of the reaction
mixture is maintained at 110.degree. .+-. 1.degree.C. until the
drop in acid value indicates that 25% of the glycidyl rings have
been esterified (ca. 6 hrs.). The batch is cooled to 50.degree.C.
and added slowly to 2700 mls. of methyl alcohol with continuous
vigorous agitation. The precipitated polymer is allowed to settle
for 24 hours and is recovered by decantation. The polymer is
airdried at room temperature for 48 hours and then for 4 hours at
50.degree.C. This polymer is then dissolved in 300 gs. of Isopar G
giving a deep clear orange solution to be used in latex
production.
EXAMPLE IX
In a 500 ml. resin reactor equipped with a stirrer, a thermometer,
a reflux condenser open to the atmosphere, a nitrogen bubbler and a
dropping funnel is placed 197.8 gs. Isopar K and warmed to
110.degree. .+-. 1.degree.C. A mixture of 86.0 gs. lauryl
methacrylate, 9.9 gs. N-1, 1, 3, 3-tetramethyl butyl
methacrylamide, 2.97 gs. glycidyl methacrylate and 0.74 gs. benzoyl
peroxide is placed in the dropping funnel and added to the hot
solvent at a constant rate over a 3 hr. period, the temperature
being maintained at 110.degree. .+-. 1.degree.C. The polymerization
is allowed to continue for 6 more hours after the last of the
monomer mixture has been added (a sample of the mixture analyzed at
this time reveals a 96.4 percent polymerization). Then 0.12 gs.
lauryl dimethyl amine is added to the mixture and it is heated for
another hour at which time 0.05 g. hydroquinone is added and a
nitrogen sparge begins. Next 1.49 gs. methacrylic acid is added and
the temperature of the mixture maintained at 110.degree. .+-.
1.degree.C. until a check of the acid content indicates that 25
percent of the glycidyl rings have been esterified (ca. 9 hrs.).
The product is a somewhat viscous, straw-colored liquid.
LATICES
The following are examples of latices prepared in accordance with
the present invention employing those of the foregoing precursors
which yield better results.
EXAMPLE X
In a 500 ml. resin reactor open to the atmosphere, and equipped
with a stirrer, a thermometer and a reflux condensor, is placed 360
g. Isopar K, 185 gs. vinyl acetate, 30 gs. of the precursor
prepared according to EXAMPLE IV, 15 gs. methyl hydrogen maleate
and 4 gs. AZBN. The temperature of the reaction mixture is raised
to 85.degree. .+-. 2.degree.C. and held there for 4 hours. An
additional 2 gs. of AZBN is then added to the mixure and the
polymerization is carried out for another 4 hours at 85.degree.
.+-. 2.degree.C. A thin blue white latex is obtained with a
particle size of 0.04 to 0.2 microns.
EXAMPLE XI
A mixture of 27.5 gs. of the precursor solution prepared according
to EXAMPLE V, 30 g. methyl methacrylate, 0.5 g. methacrylic acid
and 0.4 g. AZBN is charged along with 134 g. petroleum ether (b.p.
60.degree.-90.degree.C.) and 29.5 g. Isopar G into a 500 ml. resin
reactor open to the atmospher and is gently refluxed for 20
minutes. Then 1.4 g. of a 10 percent solution by weight of n-octyl
mercaptan in Isopar K is added to the reactor. A mixture of 166. g.
methyl methacrylate, 3.4 g. methacrylic acid 3.0 g. of the 10
percent solution of n-octyl mercaptan in Isopar K, and 0.4 g. AZBN
is dripped at a constant rate over a period of 21/2 hours. Gentle
reflux is continued for another one-half hour and the batch is then
cooled to room temperature. The resulting product is a smooth,
white, slightly viscous latex with a particle size of 0.4-1.0
microns.
EXAMPLE XII
In a 2 liter 3-neck round-bottom flask open to the atmosphere and
equipped with a stirrer, a thermometer, and a reflux condenser is
placed 848.5 g. Isopar K, 70.7 g. of the precursor solution
prepared according to EXAMPLE VIII, 471.4 g. vinly acetate and 9.4
g. AZBN. The reaction mixture is heated with constant agitationn to
86.degree.C. and the temperature is maintained for 4 hours. The
resulting product is a light lemon yellow latex with a particle
size less than 0.2 micron and a solids content of 31.7 percent.
EXAMPLE XIII
A mixture of 18 g. of the precursor solution prepared according to
EXAMPLE V, 110 g. hydroxypropyl methacrylate, 3 g. AZBN and 200 g.
Isopar K is placed into a 500 ml. resin reactor open to the
atmosphere and heated with constant agitation. The exotherm begins
at 78.degree.-80.degree.C. and the temperature rises to a maximum
of 120.degree.C. and then drops back to 80.degree.C. Polymerization
is complete in 30 minutes. A slight amount of over-size large
particle material is removed by pouring the mixture through a 200
mesh nylon screen. A white latex of 0.5 micron particle size is
obtained.
EXAMPLE XIV
A solution of 15 g. of Bakelite Union Carbide poly (vinyl ethyl
ether) (Vinylite EDBM, a poly(vinyl ethyl ehter) with a reduced
viscosity of 4.0 .+-. 0.5 as determined by using 0.1 g. polymer in
100 mls. benzene at 20.degree.C., Sp.Gr. 0.968 at 20.degree.C.) in
285 g. of Isopar G is made in a 500 ml. resin reactor open to the
atmosphere through a reflux condenser by shaving the resin into
small particles and agitating it in the solvent at 90.degree.C. for
20 hours. The solution is cooled to room temperature and 185 g.
vinyl acetate and 2.0 g. benzoyl peroxide (99%) is added. The batch
is heated until reflux occurs (ca. 95.degree.C.) and the
temperature is maintained for 4 hours. After 45 minutes of heating
at said temperature, the solution becomes turbid. After 1 hr. 15
mins. of heating at said temperature the batch becomes so viscous
that although the stirrer continues to run, no agitation is visible
and the product appears to be a thick white cream. After 2 hours of
heating at said temperature the batch begins to thin and at the end
of 3 hours of such continued heating it thins to the consistency of
heavy cream where it remains. At the end of the 4 hours, the
dropwise addition of a solution of 1.5 g. lauroyl peroxide in 30
gs. Isopar G is begun and completed over a 3 hour period while the
temperature of the system is maintained at 95.degree. .+-.
2.degree.C. The mixture is held at this temperature for 3 more
hours after the last of the lauroyl peroxide solution has been
added. The result is a white latex of 0.7-1.5 micron particle
size.
EXAMPLE XV
A mixture of 180 g. Isopar K, 100 gs. vinyl acetate, 15 gs.
precursor solution prepared according to EXAMPLE VI, and 2 gs. AZBN
is placed in a 500 ml. reaction flask equipped with a thermometer,
a stirrer, a reflux condenser and an internal cooling coil. The
reacting mixture is heated to and maintained at 86.degree. .+-.
2.degree.C. for 4 hours with continuous agitation. The flask is
open to the atmosphere through the cooled reflux condenser.
Occasionally it is necessary to cool the reacting mixture by
running water through the cooling coil during the early stages of
the reaction. The resulting product is a thin white to bluewhite
latex whose particles are too small to be viewed in an optical
microscope. The latex contains 33 percent solids.
EXAMPLE XVI
In a 5 liter jacketed glass reactor equipped with a thermometer, a
stirrer and a reflux condenser (the apparatus of EXAMPLE VI) is
placed 2160 gs. Isopar K, 180 gs. precursor prepared according to
EXAMPLE V, 1140 gs. vinyl acetate, 60 gs. N-vinyl-2-pyrrolidone and
24 gs. AZBN. The reaction mixture is heated to and maintained at 86
.+-. 2.degree.C. for 4 hours. The resulting product is a thin white
to blue-white latex whose particles are too small to be viewed in
an optical microscope.
EXAMPLE XVII
In a 500 ml. resin reactor open to the atmosphere and equipped with
a stirrer, a thermometer and a reflux condenser is placed 360 g.
Isopar K, 190 gs. vinyl acetate, 30 gs. of the precursor prepared
according to EXAMPLE V, 10 gs. crotonic acid and 4 gs. AZBN. The
temperature of the reaction mixture is raised to 85.degree. .+-.
2.degree.C. and held there for 4 hours. An additional 2 gs. of AZBN
is then added to the mixture and the polymerization is carried out
for another 4 hours at 85.degree. .+-. 2.degree.C. A thin white
latex is obtained.
EXAMPLE XVIII
In a 500 ml. resin reactor open to the atmosphere and equipped with
a stirrer, a thermometer, a thermoregulator, a reflux condenser and
an internal cooling coil is placed 40 gs. Lube Oil Additive 564
(Dupont, a 40 percent by weight solution of a 90:10 lauryl
methacrylate: diethylaminoethyl methacrylate copolymer in
kerosene), 284 gs. Isopar K and 2.2 gs. benzoyl peroxide (99%).
With continuous agitation, the batch is heated to 80.degree.C. and
maintained at that temperature for 2 hours. At this time a mixture
of 10 gs. crotonic acid and 190 gs. vinyl acetate is added all at
once to the reacted precursor which has become a dark amber. When
the temperature of the reaction mixture has returned to
80.degree.C., AZBN is added to the mixture in 0.2 g. increments at
10 min. intervals until a total of 4.6 gs. has been added (3 hrs.
40 min.). The reaction mixture is maintained at 80.degree. .+-.
2.degree.C. for 2 hours after the addition of the AZBN is complete.
A white latex is obtained of 35.7% solids with a particle size
<0.3 micron.
EXAMPLE XIX
An example of a dyeing procedure for a latex in which it is
believed that the dye does not react with the latex (although it is
possible that it may be associated therewith by hydrogen bonding)
is a mixture of 10% by weight Sudan Orange RA (Solvent Yellow 14,
C.I. No. 12055) in Isopar K the same being ball milled for 4 hours.
Twenty gs. of this dispersion is added to 100 gs. of the latex
prepared according to EXAMPLE XVII and the mixture is heated at
130.degree.-135.degree.F. for 8 hours with constant mechanical
agitation. The mixture is filtered through a 200 mesh nylon cloth
and allowed to cool to room temperature. A golden organge-colored
latex is obtained.
TONERS
The following are typical examples of working toners prepared in
accordance with the present invention and employing some of the
foregoing precursors.
EXAMPLE XX
One hundred gs. of the latex produced in EXAMPLE XVIII is placed in
a 500 ml. 3-neck round-bottom open top flask equipped with a
stirrer, a reflux condenser and a thermometer, and 2 gs. of
Victoria Blue Base BA (C.I. No. 44045B) is added to it. The
temperature is raised to 90.degree. .+-. 5.degree.C. and held there
for 2 hours. The blue latex which results is cooled and filtered
through a 200 mesh nylon cloth to remove residual dye. Four gs. of
this dyed latex is diluted with 2000 mls. Isopar K and 8 drops of a
1 percent solution of aluminum 3, 5-diisopropylsalicylate in Isopar
K is added. This latex is a complex molecule including in addition
to the solvated and non-solvated moieties (in the liquid solvent
system) a chromophore moiety. The charge director is a separate
compound. When used as a toner bath in a Dennison Standard Book
Copier, beautiful blue prints are obtained which are
background-free and smear-proof.
EXAMPLE XXI
To the batch of latex as prepared in EXAMPLE XVII is added 13.65
gs. Victoria Blue Base BA and the temperature of the mixture is
maintained at 85.degree. .+-. 2.degree.C. for 3 hours. The dark
blue latex is filtered through a 200 mesh nylon cloth and cooled to
room temperature. This toner likewise represents an example of a
chromophoric moiety which is part of a complex amphipathic
molecule. Four gs. of this latex is added to 2000 mls. Isopar G
along with 20 drops of a 1 percent solution of the aluminum salt of
3,5-di-t-butyl gamma resorcylic acid in Isopar G. This mixture,
when used as a bath in a Dennison Standard Book Copier, gives
intense, bright blue images which are background-free and
smear-proof.
EXAMPLE XXII
To the batch of latex as prepared in EXAMPLE X is added 6.8 gs.
Auramine O and 6.8 gs. Rhodamine and the temperature of the mixture
is maintained at 85.degree. .+-. 2.degree.C. for 3 hours. The now
bright yellow-orange latex is filtered through a 200 mesh nylon
cloth and cooled to room temperature. This toner likewise
represents an example of a chromophoric moiety which is part of a
complex amphipathic molecule. Ten gs. of this latex is added to
2000 mls. Isopar G along with 20 drops of a 1 percent solution of
the aluminum salt of 3,5-di-t-butyl gamma recorcylic acid in Isopar
G. This mixture, when used as a bath in a Scott 3 D Copier, gives
extremely bright orange images which are background-free,
smear-proof, and exhibit a bright orange fluorescence when exposed
to ultraviolet radiation.
EXAMPLE XXIII
To the batch of latex as prepared in EXAMPLE X is added 13.65 gs.
Victoria Green and the temperature of the mixture is maintained at
25 .+-. 2.degree.C. for 48 hours. The now dark bluish green latex
is filtered through a 200 mesh nylon cloth and cooled to room
temperature. This toner likewise represents an example of a
chromophoric moiety which is part of a complex amphipathic
molecule. Four gs. of this latex is added to 2000 mls. Isopar G
along with 20 drops of a 1 percent solution of the aluminum salt of
3,5-di-t-butyl gamm resorcylic acid in Isopar G. This mixture, when
used as a bath in a Dennison Standard Book Copier, gives intense,
bright bluish green images which are background-free and
smear-proof.
EXAMPLE XXIV
Three gs. of the latex prepared according to EXAMPLE XV are ground
together with 0.25 gs. of Raven 11 in a mortar and pestle. The
resulting paste is thinned with a little Isopar K and finally
diluted to a volume of 2000 mls. with Isopar K. To this suspension
is added 30 drops of a 1 percent solution of the aluminum salt of
3,5-di-t-butyl gamma resorcylic acid. When this suspension is used
as a toner bath in a Dennison Standard Book Copier, good prints
completely free from smearing are obtained.
EXAMPLE XXV
To the batch of latex as prepared in EXAMPLE XVII is added 13.65
gs. Crystal Violet (C.I. No. 42555B) and the temperature of the
reaction mixture is maintained at 85.degree. .+-. 2.degree.C. for 3
hours. This toner likewise represents an example of a chromophoric
moiety which is part of the complex amphipathic molecule. The
colored latex is filtered through a 200 mesh nylon cloth and cooled
to room temperature. Three gs. of this latex is added to 2000 mls.
Isopar K along with 0.05 gs. aluminum dresinate. This bath, when
used in an A-M Sunbeam 500 Copier, gives very good violet prints
with no background.
EXAMPLE XXVI
To the batch of latex as prepared in EXAMPLE XVII is added 13.65
gs. Magenta (C.I. No. 42510B) and the temperature of the reaction
mixture is maintained at 85.degree. .+-. 2.degree.C. for 3 hours.
The colored latex is filtered through a 200 mesh nylon cloth and
cooled to room temperature. This toner likewise represents an
example of a chromophoric moiety which is part of the complex
amphipathic molecule. Three gs. of this latex is added to 2000 mls.
Isopar G along with 0.05 gs. aluminum dresinate and 20 gs. of a 10
percent solution of Aerosol OT in Isopar K. When used as a toner
bath in a Dennison Standard Book Copier, magenta prints, virtually
smear-proof and background-free, are obtained.
EXAMPLE XXVII
This is an example of a reversal developer. To the batch of latex
as prepared in EXAMPLE XVII is added 13.65 of Victoria Blue (C.I.
No. 44045B) and the temperature of the reaction mixture is
maintained at 85.degree. .+-. 2.degree.C. for 3 hours. The colored
latex is filtered through a 200 mesh nylon cloth and cooled to room
temperature. This toner likewise represents an example of a
chromophoric moiety which is part of the complex molecule. Six gs.
of this latex is added to 2000 mls. Isopar K along with 0.6 gs.
OLOA 1200. This bath, when used in an A-M Sunbeam Copier, gives
good blue reversal prints.
EXAMPLE XXVIII
This is an example of a reversal developer. To the batch of latex
as prepared in EXAMPLE X is added 6.8 gs. Auramine O and 6.8 gs.
Rhodamine and the temperature of the mixture is maintained at
85.degree. .+-. 2.degree.C. for 3 hours. The now bright
yellow-orange latex is filtered through a 200 mesh nylon cloth and
cooled to room temperature. This toner likewise represents an
example of a chromophoric moiety which is part of the complex
molecule. 8.0 gs. of this latex are added to 2500 mls. of Isopar G
along with 100 .mu. liters of a 34.8 percent by weight solution of
the aluminum salt of a 50--50 by weight mixture of the mono- and
di-2 ethylhexyl esters of phosphoric acid in Isopar H and 10 mls.
of a 10% by weight solution of Alkanol DOA in Isopar H. This
mixture, when used as a bath in a Scott 30 Copier, gives extremely
bright orange reversal prints.
EXAMPLE XXIX
Four gs. of the latex produced according to the EXAMPLE XIX is
added to 2000 mls. Isopar K along with 20 drops of a 1 percent
solution of aluminum diisopropyl salicylate in Isopar G. This
mixture, when used as a bath in a Dennison Standard Book Copier,
gives yellowish-orange images which are background-free and
smear-proof.
The foregoing toner examples have each time mentioned but a single
color agent. Optionally, plural coloring agents may be used and it
is usually preferred to employ two or more color agents, the
conjoint action of which is to produce a deep color such, for
example, as a brown-black, blue-black or purple-black.
The present invention can be carried out in still another fashion,
although it still involves, of course, the use of a multifunctional
complex molecule having a polymeric moiety solvated by and a
polymeric moiety unsolvated by the liquid solvent system; this is
to form the amphipathic polymer molecule in a solvent in which such
molecule is completely solvated and then by adding another solvent
which is a nonsolvent for a moiety of the polymer but is miscible
with the first solvent, and desolvating this moiety of the
amphipathic polymer molecule while said desolvated moiety remains
bonded to the solvated moiety of the polymer, i.e., remains as a
part of the polymer. If desired, all or a part of the first solvent
can then be withdrawn. This is an extremely easy general way for
obtaining a block amphipathic polymer as the dispersed phase in
accordance with the present invention. As an example of the
foregoing a block polymer of polyisoprene-polystyrene-polyisoprene
is formed by anionic polymerization.
EXAMPLE XXX
9.2 gs. of styrene are added to 60 cc. of tetrahydrofuran
containing 3.3 .times. 10.sup.-.sup.4 mole of sodium naphthalene (a
catalyst) at -80.degree.C. in a three-neck round bottom flask
equipped with a mechanical stirrer, a thermometer and a nitrogen
inlet in a dry ice bath. The reaction is completed in 15 minutes,
resulting in the formation of a "living" polystyrene polymer. Upon
completion of polymerization 6.3 gs. of isoprene is added (still at
-80.degree.C.) and the isoprene polymerizes on the living ends of
the polystyrene to form a block polymer. The now living ends of
this block polymer, which block polymer is solvated by the
tetrahydrofuran, are then grafted on to a suitable backbone polymer
as by reacting at room temperature with 3 gs. of the precursor
solution of EXAMPLE VIII to form the amphipathic polymer. Said
backbone (precursor) polymer likewise is solvated by the
tetrahydrofuran and such polymer is made the solvated phase of a
nonsolvent for the block polymer of the system. Thereby the block
polymer moiety is desolvated. The non-solvent employed is OMS which
is added at room temperature to the solvated poly
(styrene/isoprene)/poly (lauryl methacrylate - glycidyl
methacrylate - methacrylic acid - p-phenolazoacrylanilide)
amphipathic polymer to form a latex. To transform this colored
(golden-yellow) latex into a working toner there is added to 15 gs.
of the latex 2000 ml. of OMS and 30 drops of a 1 percent solution
of the aluminum salt of 3,5-di-t-butyl gamma resorcyclic acid. When
this toner is employed as a bath in a Dennison Standard Book Copier
good prints are obtained.
There have been mentioned above various characteristics of the
toner of the present invention, and specifically the fact that it
provides a mono-dispersed particle size and makes use of an
amphipathic molecule which has the ability to be either
bifunctional or tri-functional. However, there are further
advantages to the unique toner which, like the ones just mentioned,
are of very substantial commercial importance. These include the
ability of the new toner to provide a very quick fixing of a
freshly developed image, as well as the ability to function in
widely diverse types of equipment wherein liquid electrostatic
toners are employed.
Referring to the fast-acting fixation chacteristic of the new
toner, the same is specially useful in high speed development. The
present toner can, of course, be employed in all conventional
electrostatographic copy machines, both office copy machines which
are found, e.g., in small offices, and somewhat higher speed copy
machines such as machines which produce 660, 2400 and 3600 printed
sheets per hour, which machines, as soon will be seen, are
relatively slow. There are other uses where a liquid electrostatic
toner could be widely employed if only the fixing were sufficiently
rapid. One such use is for computer read-outs. Computers as a class
have an ability to generate information at a tremendous rate. The
current generation of computers has the ability to generate as many
as a billion characters a second. This is far beyond the capability
of electrostatic development due, principally, to the comparatively
slow speed at which the initial fixing takes place. This initial
fixing occurs between the time that the electrostatic substrate
with the freshly developed image on it leaves the developer and the
time that the image is to be physically manipulated by equipment in
a manner such that the freshly developed image is touched by a
piece of equipment or a reverse side of another substrate or a part
of the same substrate. By this it is meant that the substrate with
the freshly electrostatically developed image, after passing
through a dryer which handles the substrate by its edges, has to be
compacted. The compaction usually will be by rolling up the
substrate into the form of a convoluted cylinder or manifolding it,
e.g., fan-folding it. If the freshly developed image at this time,
which, e.g., is 20 seconds after it has left the developing bath,
is not fully fixed, it will tend to smear or off-set, both of which
make the process economically undesirable. The toner of the present
invention, however, makes an initial fix of the freshly developed
image so quickly that this problem has been overcome. In other
words, the toner of the present invention will electrostatically
develop an image which, within as little as 20 seconds after
formation and even without the necessity of applying heat, will be
set to the point where the substrate bearing the image can be
handled by machine parts or pressed against a reverse face of
another substrate or another part of the substrate without causing
smearing. Accordingly, the new toner is particularly useful for
rapid development despite the fact that it is also very
advantageous to use in ordinary electrostatographic development at
lesser output rates.
It also should be observed that the new toner can be employed in
such widely diverse types of equipment as the enlarged reproduction
of microfilms, either at normal speeds or at high speeds. It
further can be used in the reproduction section of facsimile
receiving equipment and it forms an excellent electrostatic
developer for instrument recording, whether the instrument employs
as the moving element an electron beam or an actinic beam, which
may be caused to leave a trace on a statically charged substrate by
a mirror movable about plural axes.
An additional advantage of the new toner is that it can be used
with equal facility to develop both actinically sensitive and
actinically non-sensitive electrostatic types of substrates, so
that the same principle can be employed in making the toner
regardless of which end use is to be employed. Still another type
of equipment with which the new toner is fully compatible is
electrophotographic cathode ray apparatuses, such, e.g., as the
Stromberg Datagraphix. In this type of equipment an electrostatic
latent image is formed with the use of a cathode ray tube and is
printed off, i.e., transferred, to a uniformly charged zinc oxide
paper, the process essentially being an electrophotographic one.
Still another type of apparatus that can be employed with the new
toner is the A.B. Dick Videograph in which the latent image is
formed with the aid of a cathode ray pin tube. Nor should one
overlook the ability of the toner to be used with the Varian Statos
recorder. Furthermore, the novel toner of the present invention can
be utilized by direct application in the manufacture of printed
circuit boards.
In all of the foregoing uses mentioned just above the toner is
utilized to form a visible deposit or representation by
preferential attraction to a differentially electrostatically
charged substrate. However, the toner is not limited to this kind
of process and can be used in other processes where, in general,
the liquid toner is characterized by the presence of a liquid
solvent system carrying colored particles or coloring in general.
The toner of the present invention, thus, can be and has been
successfully employed in jet ink beam printing wherein the toner is
shaped into a moving fine stream which is projected from a portion
of the apparatus on to a graphic reception type of substrate which
need not be electrostatically charged. The jetted beam of ink,
preferably broken up into droplets, has its flight path controlled
by passage between pairs of electrostatic deflecting plates, these
plates altering the physical orientation of the parts of the beam
passing between them by varying the electrostatic charge thereon as
a function of certain intelligence which is fed into the plates.
Such method can be practiced only because the liquid solvent system
is highly non-conductive and, therefore, capable of being charged
so as to react properly with fluctuating electrostatic fields
through which it passes. The toner of the present invention is
particularly efficient in equipment of this character because of
its low viscosity which permits the jet to be formed into a very
fine beam and because of its high surface tension which facilitates
the subdivision of the beam into droplets so that the same can be
moved with greater celerity by electrostatic means.
Not to be overlooked in any of the foregoing is the fact that, in
addition to the quick initial fixing which avoids ready smearing
while the image is still fresh, the present toner has the decided
advantage that a fully dried image will not smear even when
deliberate efforts are made to distort the image as by rubbing a
finger across a developed image. It is believed that the initial
ability to resist smearing of a freshly developed image and the
subsequent ability to resist smearing of an image in handling by
people is largely due to the fact that, with an amphipathic
molecule of the character which predominates in the toner of the
instant invention, the liquid solvent system more readily
disassociates from the molecule so as to escape into the ambient
atmosphere and leave a quickly initially substantially, and
subsequently fully, dried developed visible area. Also the solvent
is able to escape more readily from a deposited film principally
constituted of such amphipathic molecules.
It thus will be seen that there are provided methods and
compositions which achieve the several objects of the invention and
which are well adapted to meet the conditions of practical use.
As various possible embodiments might be made of the above
invention and as various changes might be made in the embodiments
above set forth, it is to be understood that all matter herein
described is to be interpreted as illustrative and not in a
limiting sense.
* * * * *