U.S. patent number 3,893,935 [Application Number 05/399,226] was granted by the patent office on 1975-07-08 for electrographic toner and developer composition.
This patent grant is currently assigned to Eastman Kodak Company. Invention is credited to Thomas A. Jadwin, Alec N. Mutz, Bruce J. Rubin.
United States Patent |
3,893,935 |
Jadwin , et al. |
July 8, 1975 |
Electrographic toner and developer composition
Abstract
The present invention relates to the use of certain quaternary
ammonium salts as useful charge control agents for an electrostatic
toner composition.
Inventors: |
Jadwin; Thomas A. (Rochester,
NY), Mutz; Alec N. (Rochester, NY), Rubin; Bruce J.
(Rochester, NY) |
Assignee: |
Eastman Kodak Company
(Rochester, NY)
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Family
ID: |
26946027 |
Appl.
No.: |
05/399,226 |
Filed: |
September 20, 1973 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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257524 |
May 30, 1972 |
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Current U.S.
Class: |
430/108.2 |
Current CPC
Class: |
G03G
9/09741 (20130101) |
Current International
Class: |
G03G
9/097 (20060101); G03g 009/00 () |
Field of
Search: |
;252/62.1
;117/DIG.4 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1,117,224 |
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Jun 1968 |
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GB |
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1,174,573 |
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Dec 1969 |
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GB |
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1,169,703 |
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Nov 1969 |
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GB |
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1,034,849 |
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Jul 1958 |
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DT |
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Primary Examiner: Farley; Richard A.
Assistant Examiner: Blum; T. M.
Attorney, Agent or Firm: Hilst; R. P.
Parent Case Text
This application is a continuation-in-part of U.S. Ser. No. 257,524
abondoned filed May 30, 1972.
Claims
We claim:
1. A dry particulate electroscopic toner composition for use in
developing electrostatic charge patterns comprising finely-divided
particles comprising a resin having incorporated therein a
quaternary ammonium charge control agent having the following
formula: ##EQU3## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4
represent an aliphatic hydrocarbon group having one to seven carbon
atoms and X.sup.- represents an anionic function.
2. A dry particulate electroscopic toner composition for use in
developing electrostatic charge patterns comprising finely-divided
particles having a particle size of from about 0.1 micron to about
100 microns, said particles comprising a resin having a melting
point within the range of from about 65.degree. to about
200.degree.C. and having incorporated in said resin a quaternary
ammonium charge control agent having the following formula:
##EQU4## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 represent an
aliphatic hydrocarbon group having one to seven carbon atoms and
X.sup.- represents an anionic function, said particles comprising
about 0.1 to about 6 parts by weight charge control agent per 100
parts by weight of said resin.
3. The invention as described in claim 2 wherein said toner
composition comprises a pigment or a dyestuff in an amount
effective to color said toner composition.
4. A dry particulate electroscopic toner composition for use in
developing electrostatic charge patterns comprising finely-divided
particles having a particle size of from about 1.0 to about 30
microns, said particles comprising a styrene-containing resin
having a melting point within the range of from about 65.degree.C.
to about 120.degree.C. and having incorporated in said resin (a) a
pigment or dyestuff in an amount effective to color said resin and
(b) a quaternary ammonium charge control agent having the following
formula: ##EQU5## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4
represent an aliphatic hydrocarbon group having one to seven carbon
atoms and where X.sup.- is an anionic function, said particles
comprising about 0.3 to about 3.0 parts by weight charge control
agent per 100 parts by weight of said resin.
5. The invention as described in claim 4 wherein R.sup.1, R.sup.2,
R.sup.3 and R.sup.4 represent an alkyl group having from 1 to about
7 carbon atoms and wherein X.sup.- is an anionic function selected
from the group consisting of halides, phosphates, acetates and
nitrates.
6. The invention as described in claim 4 wherein R.sup.1, R.sup.2,
R.sup.3, and R.sup.4 are straight-chain alkyl groups having from
about 3 to about 7 carbon atoms and wherein X.sup.- is a
halide.
7. The invention as described in claim 4 wherein R.sup.1, R.sup.2,
R.sup.3, and R.sup.4 are straight-chain alkyl groups having from
about 3 to about 7 carbon atoms and wherein X.sup.- is a
chloride.
8. A dry particulate electroscopic toner composition for use in
developing electrostatic charge patterns comprising finely-divided
particles of from about 0.1 micron to about 100 microns, said
particles comprising a polycarbonate-containing resin having a
glass transition temperature within the range of from about
60.degree.C. to about 120.degree.C. and having incorporated in said
resin (a) a dyestuff or pigment in an amount effective to color
said resin and (b) a quaternary ammonium charge control agent
having the following formula: ##EQU6## wherein R.sup.1, R.sup.2,
R.sup.3 and R.sup.4 represent an aliphatic hydrocarbon group having
one to seven carbon atoms and wherein X.sup.- is an anionic
function.
9. The invention as described in claim 8 wherein R.sup.1, R.sup.2,
R.sup.3 and R.sup.4 represent an aliphatic group having from 1 to
about 7 carbon atoms and wherein X.sup.- is an anionic function
selected from the group consisting of halides, phosphates, acetates
and nitrates.
10. The invention as described in claim 8 wherein R.sup.1, R.sup.2,
R.sup.3 and R.sup.4 represent an alkyl group having from about 3 to
about 7 carbon atoms and wherein X is a halide.
11. A dry particulate electroscopic toner composition for use in
developing electrostatic charge patterns comprising finely-divided
particles of from about 1.0 to about 30 microns, said particles
comprising a styrene-containing resin having a melting point within
the range of from about 65.degree.C. to about 120.degree.C., said
resin containing from about 40 to about 100 percent by weight of
styrene units, from 0 to about 45 percent by weight of alkyl
acrylate or alkyl methacrylate units having from 1 to about 3
carbon atoms in the alkyl moiety, and from about 5 to about 50
percent by weight of alkyl acrylate or alkyl methacrylate units
having from about 6 to about 20 carbon atoms in the alkyl moiety,
said resin having incorporated therein (a) a pigment or dyestuff in
an amount effective to color said resin and (b) a quaternary
ammonium charge control agent having the following formula:
##EQU7## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4 represent an
aliphatic hydrocarbon group having one to seven carbon atoms and
wherein X.sup.- is an anionic function, said particles comprising
about 0.1 to about 6 parts by weight charge control agent per 100
parts by weight of said resin.
12. The invention as described in claim 11 wherein R.sup.1,
R.sup.2, R.sup.3 and R.sup.4 represent an aliphatic group having
from 1 to about 7 carbon atoms and wherein X.sup.- is an anionic
function selected from the group consisting of halides, acetates,
phosphates, and nitrates.
13. The invention as described in claim 11 wherein said particles
contain carbon black as a pigment.
14. The invention as described in claim 11 wherein R.sup.1,
R.sup.2, R.sup.3 and R.sup.4 represent an alkyl group having from
about 3 to about 7 carbon atoms and wherein X is a halide.
15. An electrographic developing composition comprising particulate
magnetic carrier particles having electrostatically attractable
thereto a toner composition as described in claim 1.
16. An electrographic developer composition comprising
ferromagnetic carrier particles having a particle size within the
range of from about 30 to about 1200 microns and having
electrostatically attractable thereto dry, finely-divided toner
particles having a particle size within the range of about 1.0 to
about 30 microns, said toner particles comprising a resin having a
melting point within the range of from about 65.degree. to about
200.degree.C. and having incorporated in said resin (a) a dyestuff
or pigment in an amount effective to color said resin and (b) a
quaternary ammonium charge control agent having the following
formula: ##EQU8## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4
represent an aromatic or an aliphatic hydrocarbon group having one
to seven carbon atoms and wherein X.sup.- is an anionic function,
said toner particles comprising about 0.3 to about 3.0 parts by
weight of charge control agent per 100 parts by weight of said
resin.
17. The invention as described in claim 16 wherein said resin is a
styrene-containing resin having a melting point within the range of
about 65.degree. to about 120.degree.C. and wherein said toner
particles comprise carbon black as a pigment.
18. The invention as described in claim 16 wherein said resin is a
poly(carbonate)-containing resin having a glass transition
temperature within the range of from about 60.degree. to about
120.degree.C. and wherein said toner particles comprise carbon
black as a pigment.
Description
This invention relates to electrography and to a particulate toner
composition and a dry electrographic developer composition
containing such a toner useful in the development of latent
electrostatic charge images.
Electrographic imaging and developing processes, eg.
electrophotographic imaging processes and techniques, have been
extensively described in both the patent and other literature, for
example, U.S. Pat. No. 2,221,776 issued Nov. 19, 1940; No.
2,277,013 issued Mar. 17, 1942; No. 2,297,691 issued Oct. 6, 1942;
No. 2,357,809 issued Sept. 12, 1944; No. 2,551,582 issued May 8,
1951; No. 2,825,814 issued Mar. 4, 1958; No. 2,833,648 issued May
6, 1958; No. 3,220,324 issued Nov. 30, 1965; No. 3,220,831 issued
Nov. 30, 1965; No. 3,220,833 issued Nov. 30, 1965; and many others.
Generally these processes have in common the steps of forming a
latent electrostatic charge image on an insulating electrographic
element. The electrostatic latent image is then rendered visible by
a development step in which the charged surface of the
electrographic element is brought into contact with a suitable
developer mix. Conventional dry developer mixes include toner or
marking particles and may also include a carrier vehicle that can
be either a magnetic material such as iron filings, powdered iron
or iron oxide, or a triboelectrically chargeable, non-magnetic
substance like glass beads or crystals of inorganic salts such as
sodium or potassium fluoride. The toner or marking particles
typically contain a resinous material suitably colored or darkened,
for contrast purposes, with a colorant like dyestuffs or pigments
such as carbon black.
One method for applying a suitable dry developer mix to a charged
image-bearing electrographic element is by the well-known magnetic
brush process. Such a process generally utilizes an apparatus of
the type described, for example, in U.S. Pat. No. 3,003,462 issued
Oct. 10, 1961 and customarily comprises a non-magnetic rotatably
mounted cylinder having fixed magnetic means mounted inside. The
cylinder is arranged to rotate so that part of the surface is
immersed in or otherwise contacted with a supply of developer mix.
The granular mass comprising the developer mix is magnetically
attracted to the surface of the cylinder. As the developer mix
comes within the influence of the field generated by the magnetic
means within the cylinder, particles thereof arrange themselves in
bristle-like formations resembling a brush. The brush formations
that are formed by the developer mix tend to conform to the lines
of magnetic flux, standing erect in the vicinity of the poles and
laying substantially flat when said mix is outside the environment
of the magnetic poles. Within one revolution the continually
rotating cylinder picks up developer mix from a supply source and
returns part or all of this material to this supply. This mode of
operation assures that fresh mix is always available to the surface
of the charged electrographic element at its point of contact with
the brush. In a typical rotational cycle, the roller performs the
successive steps of developer mix pickup, brush formation, brush
contact with the electrographic element, eg. a photoconductive
element, brush collapse and finally mix release.
In magnetic brush development, as well as in various other types of
electrographic development wherein a dry triboelectric mixture of a
particulate carrier vehicle and a toner powder are utilized, e.g.,
cascade development such as described in U.S. Pat. Nos. 2,638,416
and 2,618,552, it is advantageous to modify the surface properties
of the toner powder so that a uniform, stable high net electrical
charge may be imparted to the toner powder by the particulate
carrier vehicle.
A variety of methods and material for modifying the surface
properties of particulate toner particles have been proposed. For
example, Olson, U.S. Pat. No. 3,647,696 issued Mar. 7, 1972
describes a uniform polarity resin electrostatic toner containing a
mono- or di-functional organic acid nigrosine salt. The nigrosine
salt described in U.S. Pat. No. 3,647,696 aids in providing a
relatively high uniform net electrical charge to a toner powder
containing such a nigrosine salt. However, subsequent testing and
development relating to the use of such organic acid nigrosine
salts has shown that such materials, when incorporated in a toner
composition, contribute to a decrease in the adhesion of the toner
particles to a suitable paper receiving sheet. For example, it has
been found that when a toner image is transferred from a charge
image-bearing electrographic element to a paper receiving sheet and
fixed to the receiving sheet, the image formed on the receiving
sheets tends to flake off when the sheet is bent or folded.
Other materials which have been employed as modifying agents for
dry toner compositions include various long-chain anionic or
cationic materials such as various surfactants. Typical of these
surfactant materials are the long chain quaternary ammonium
surfactants. The use of such materials is described for example in
British Pat. No. 1,174,573 published Dec. 17, 1969, at page 2,
column 2 through page 3. In addition, Jacknow et al., U.S. Pat. No.
3,577,345 issued May 4, 1971, describes a solid metal salt of a
fatty acid admixed with one of various other described solid
additives as a useful modifying combination for a dry toner
composition.
Other patents which describe various components for use in liquid
developers include Beyer, U.S. Pat. No. 3,417,019 issued Dec. 17,
1968, which describes, in part, the use of various metal soaps, for
example cobalt naphthenate, for use as a charge control agent in a
liquid developer toner composition.
In accordance with the present invention, it has been discovered
that certain quaternary ammonium salts incorporated in a dry,
particulate toner composition comprising a resin and, if desired, a
suitable colorant such as a pigment or dye, provide an effective
charge control agent for the toner composition. Typical of the
quaternary ammonium salts useful in the present invention are
materials having the following formula: ##EQU1## wherein R.sup.1,
R.sup.2, R.sup.3 and R.sup.4 which may be the same or different
represent an aliphatic hydrocarbon group having seven or less,
preferably 3 to about 7, carbon atoms, including straight-chain and
branched-chain aliphatic hydrocarbon groups, and X.sup.- represents
an anionic function.
The quaternary ammonium salt charge control agents, when
incorporated in the toner materials of the present invention, have
been found surprisingly effective in providing a particulate toner
composition which exhibits a relatively high, uniform and stable
net toner charge when admixed with a suitable particulate carrier
vehicle and which also exhibits a minimal amount of deleterious
toner throwoff. The charge control agent used in the present
invention has been found substantially more effective than the
somewhat related long-chain quaternary ammonium surfactant
materials which previously have been incorporated in toner
compositions. More specifically, the quaternary ammonium salts of
the present invention have been found to exhibit a substantially
higher net toner charge and a substantially lower toner throw-off
than long-chain quaternary ammonium salt surfactants (or wetting
agents as they are sometimes called). (See Example 1 set forth
hereinafter.) In addition, the quaternary ammonium charge control
agents used in the present invention have been found to have no
deleterious effect on the adhesion properties of the resultant
toner composition containing these charge control agents to
conventional paper receiving sheets.
A further indicia of the uniqueness of the toner compositions of
the present invention is the fact that these compositions
containing quaternary ammonium salts exhibit substantially better
"charge control" properties than toner compositions containing
other types of onium salts, e.g., sulfonium, phosphonium,
pyridinium, or quinolinium salts. (see Example 1 set forth
hereinafter.)
Moreover, it has been found that particulate resinous toner
particles containing an effective amount of the above-described
quaternary ammonium charge control agents generally result in good
to excellent electrographic developed images exhibiting increased
and uniform density with little or no background scumming.
The resins useful in the practice of the present invention can be
used alone or in combination and include those resins
conventionally employed in electrostatic toners. Useful resins
generally have a glass transition temperature within the range of
from 60.degree. to 120.degree.C. Preferably, toner particles
prepared from these resinous materials have relatively high caking
temperature, for example, higher than about 55.degree.C., so that
the toner powders may be stored for relatively long periods of time
at fairly high temperatures without having individual particles
agglomerate and clump together. The melting point of useful resins
preferably is within the range of from about 65.degree.C. to about
200.degree.C. so that the toner particles can readily be fused to
conventional paper receiving sheet to form a permanent image.
Especially preferred resins are those having a melting point within
the range of from about 65.degree.C to about 120.degree.C. Of
course, where other types of receiving elements are used, for
example, metal plates such as certain printing plates, resins
having a melting point and glass transition temperature higher than
the values specified above may be used.
As used herein the terms "melting point" refers to the melting
point of a resin as measured by Fisher Johns apparatus, Fisher
Scientific Catalog No. 12-144. Glass transition temperature (Tg) as
used herein refers to the temperature at which a polymeric material
changes from a glassy polymer to a rubbery polymer. This
temperature (Tg) can be measured by differential thermal analysis
as disclosed in Techniques and Methods of Polymer Evaluation, Vol.
1, Marcel Dekker, Inc., N.Y. 1966.
Among the various resins which may be employed in the toner
particles of the present invention are polystyrene containing
resins, polycarbonates, rosin modified maleic alkyd resins,
polyamides, phenol-formaldehyde resins and various derivatives
thereof, polyester condensates, modified alkyd resins and the like,
aromatic resins containing alternating methylene and aromatic units
such as described in Merrill et al., U.S. Ser. No. 168,389, now
Pat. No. 3,809,554 filed Aug. 2, 1971, and the like.
Typical useful toner resins include certain polycarbonates such as
those described in U.S. Pat. No. 3,694,359 issued Sept. 26, 1972,
and which includes polycarbonate materials containing an alkylidene
diarylene moiety in a recurring unit and having from 1 to about 10
carbon atoms in the alkyl moiety. Other useful resins having the
above-described physical properties include polymeric esters of
acrylic and methacrylic acid such as poly(alkylacrylate) including
poly(alkylmethacrylate) wherein the alkyl moiety can contain from 1
to about 10 carbon atoms. Additionally, other polyesters having the
aforementioned physical properties are also useful. Among such
other useful polyesters are copolyesters prepared from terephthalic
acid including substituted terephthalic acid, a bis(hydroxyalkoxy)
phenylalkane having from 1 to 4 carbon atoms in the alkoxy radical
and from 1 to 10 carbon atoms in the alkane moiety and including
such halogen substituted alkanes, and an alkylene glycol having
from 1 to 4 carbon atoms in the alkylene moiety.
Other useful resins are various styrene-containing resins. Such
polymers typically comprise a polymerized blend of from about 40 to
about 100 percent by weight of styrene, from about 0 to about 45
percent by weight of a lower alkyl acrylate or methacrylate having
from 1 to about 4 carbon atoms in the alkyl moiety such as methyl,
ethyl, isopropyl, butyl, etc. and from about 5 to about 50 percent
by weight of another vinyl monomer other than styrene, for example,
a higher alkyl acrylate or methacrylate having from about 6 to 20
or more carbon atoms in the alkyl group. A typical
styrene-containing resin prepared from a copolymerized blend as
described hereinabove are copolymers prepared from a monomeric
blend of 40 to 60 percent by weight styrene or styrene homolog,
from about 20 to about 50 percent by weight of a lower alkyl
acrylate or methacrylate and from about 5 to about 30 percent by
weight of a higher alkyl acrylate or methacrylate such as
ethylhexyl acrylate. A variety of other useful styrene containing
toner materials are disclosed in the following U.S. Pats. No.:
2,917,460 issued Dec. 15, 1959; Re. No. 25,136 issued Mar. 13,
1962; No. 2,788,288 issued Apr. 9, 1957; No. 2,638,416 issued Apr.
12, 1953; No. 2,618,552 issued Nov. 18, 1952 and No. 2,659,670
issued Nov. 17, 1953.
The toner particles of the present invention can be prepared by
various methods. One convenient technique for preparing these
toners is spray-drying. Spray-drying involves dissolving the
polymer and adding the toner colorant and charge control agent to a
volatile organic solvent such as dichloromethane. This solution is
then sprayed through an atomizing nozzle using a substantially
nonreactive gas such as nitrogen as the atomizing agent. During
atomization, the volatile solvent evaporates from the airborne
droplets, producing toner particles of the uniformly dyed or
pigmented resin. The ultimate particle size is determined by
varying the size of the atomizing nozzle and the pressure of the
gaseous atomizing agent. Particles of a diameter between about 0.1
micron and about 100 microns may be used, although in general
present day office copy devices typically employ particles between
about 1.0 and 30 microns. However, larger particles or smaller
particles can be used where desired for particular methods of
development or particular development conditions. For example, in
powder cloud development such as described in U.S. Pat. No.
2,691,345 issued Oct. 12, 1954, extremely small toner particles are
used.
Another convenient method for preparing the toner composition of
the present invention is melt-blending. This technique involves
melting a powdered form of polymer or resin and mixing it with
suitable colorants, such as dyes or pigments, and the charge
control agent. The resin can readily be melted on heated
compounding rolls which are also useful to stir or otherwise blend
the resin and addenda so as to promote the complete intermixing of
these various ingredients. After thorough blending, the mixture is
cooled and solidified. The resultant solid mass is then broken into
small particles and finely ground to form a free-flowing powder of
toner particles. These particles typically have an average particle
size or average diameter within the range of from about 0.1 to
about 100 microns.
As described hereinabove the quaternary ammonium charge control
agents of the invention are added to the resinous toner composition
in an amount effective to improve the charge properties of the
toner composition. The addition of a charge control agent improves
the charge uniformity of a particular toner composition, i.e. acts
to provide a toner composition in which all or substantially all of
the individual discrete toner particles exhibit a triboelectric
charge of the same sign (negative or positive) with respect to a
given carrier vehicle, increases the net electrical charge
exhibited by a specified quantity of toner particles relative to a
given carrier vehicle, and reduces the amount of "toner throw-off"
of a given toner composition. As used herein, the phrases "net
electrical charge exhibited by a toner powder" or "net toner
charge" are equivalent and are defined as the total electrical
charge exhibited by a specified amount of a particular toner when
admixed with a specified amount of a particular carrier vehicle.
Although the phenomenon by which such an electrical charge is
imparted is not fully understood, it is believed due in large to
the triboelectric effect caused by the physical admixture of toner
and carrier. As used herein, the term toner throw-off is defined as
the amount of toner powder thrown out of a developer mix as it is
mechanically agitated, e.g., in a development apparatus. Aside from
the extraneous contamination problems inherent with airborne toner
dust in the development apparatus, toner throw-off also leads to
imaging problems such as unwanted background and scumming of the
electrographic image-bearing element.
Generally, it has been found desirable to add from about 0.1 to
about 6 parts and preferably 0.3 to about 3.0 parts by weight of
the aforementioned quaternary ammonium salts per 100 parts by
weight of a resinous binder to obtain the improved toner
composition of the present invention. Although larger and smaller
amounts of a charge control agent may be added, it has been found
that if amounts much lower than those specified above are utilized,
the charge control agent tends to exhibit little or substantially
no improvement in the properties of the toner composition. As
amounts more than about 6 parts of charge control agent per 100
parts of resinous binder are added, it has been found that the net
toner charge exhibited by the resultant toner composition tends to
be reduced. Of course, it must be recognized that the optimum
amount of charge control agent to be added will depend, in part, on
the particular quaternary ammonium charge control agents selected
and the particular resinous binder to which it is added. However,
the amounts specified hereinabove are typical of the useful range
of charge control agent utilized in conventional dry toner
materials.
As indicated, the quaternary ammonium charge control agents
contemplated for use according to the present invention have the
formula: ##EQU2## wherein R.sup.1, R.sup.2, R.sup.3 and R.sup.4
which may be the same or different represent an aliphatic
hydrocarbon group having one to seven carbon atoms and X.sup.- is
an anionic function. R.sup.1, R.sup.2, R.sup.3 and R.sup.4 may be a
straight chain or branched chain aliphatic hydrocarbon groups
including allyl and alkyl moieties, e.g., methyl, ethyl, propyl,
butyl, pentyl, hexyl, heptyl, isopropyl, etc. Especially good
results have been obtained wherein R.sup.1, R.sup.2, R.sup.3 and
R.sup.4 are each an alkyl moiety having 3-7 carbon atoms and
wherein each of R.sup.1, R.sup.2, R.sup.3 and R.sup.4 represents an
identical alkyl moiety. As can be observed from the above list, a
variety of hydrocarbon substituents may be utilized in the
quaternary ammonium salt charge control agents of the present
invention. In addition, a variety of conventional anionic moieties
may be utilized such as the following: halides such as chloride,
bromide, iodide, phosphates; acetates; nitrates; benzoates; methyl
sulfate, perchlorate, tetrafluoroborate, benzenesulfonate, and the
like. Especially useful anionic moieties are the halides. Typical
of the quaternary salts useful in the invention are the
following:
Tetrapentylammonium chloride
Tetraheptylammonium chloride
Tetrapentylammonium hexafluorophosphate
Tetraethylammonium benzoate
Tetraethylammonium acetate tetrahydrate
Tetrapentylammonium bromide
Tetrabutylammonium iodide
Tetrabutylammonium nitrate
Triethylmethylammonium iodide
A variety of colorant materials selected from dyestuffs or pigments
may be employed in the toner materials of the present invention.
Such materials serve to color the toner and/or render it more
visible. Of course, suitable toner materials having the appropriate
charging characteristics can be prepared without the use of a
colorant material where it is desired to have a developed image of
low optical opacity. In those instances where it is desired to
utilize a colorant, the colorants used, can, in principle, be
selected from virtually any of the compounds mentioned in the
Colour Index Volumes 1 and 2, Second Edition.
Included among the vast number of useful colorants would be such
materials as Hansa Yellow G (C.I. 11680), Nigrosine Spirit soluble
(C.I. 50415) Chromogen Black ET00 (C.I. 45170), Solvent Black 3
(C.I. 26150), Fuchsine N (C.I. 42510), C.I. Basic Blue 9 (C.I.
52015), etc. Carbon black also provides a useful colorant. The
amount of colorant added may vary over a wide range, for example,
from about 1 to about 20 percent of the weight of the thermoplastic
resin. Particularly good results are obtained when the amount is
from about 2 to about 10 percent. In certain instances, it may be
desirable to omit the colorant, in which case the lower limit of
concentration would be zero.
The toners of this invention can be mixed with a carrier vehicle to
form developing compositions. The carrier vehicles which can be
used with the present toners to form new developer compositions can
be selected from a variety of materials. Suitable carrier vehicles
useful in the invention include various nonmagnetic particles such
as glass beads, crystals of inorganic salts such as sodium or
potassium chloride, hard resin particles, metal particles, etc. In
addition, magnetic carrier particles can be used in accordance with
the invention. In fact, the toner compositions of the present
invention are especially suited for use with magnetic carrier
particles as the problem of toner throw-off is especially
bothersome in magnetic brush development processes. Suitable
magnetic carrier particles are particles of ferromagnetic materials
such as iron, cobalt, nickel, and alloys and mixtures thereof.
Other useful magnetic carriers are ferromagnetic particles
overcoated with a thin layer of various film-forming resins, for
example, the alkali-soluble carboxylated polymers described in
Miller, U.S. Pat. No. 3,547,822 issued Dec. 15, 1970; Miller, U.S.
Pat. No. 3,632,512 issued Jan. 4, 1972; McCabe, U.S. Ser. No.
236,765, now Pat. No. 3,795,617 filed Mar. 21, 1972, entitled
"Electrographic Carrier Vehicle and Developer Composition -- Case
B"; Kasper et al., U.S. Ser. No. 236,584, now abandoned, filed Mar.
21, 1972, entitled "Electrographic Carrier Vehicle and Developer
Composition -- Case C"; and Kasper U.S. Ser. No. 236,614, now U.S.
Pat. No. 3,795,618 filed Mar. 21, 1972, entitled, "Electrographic
Carrier Vehicle and Developer Composition -- Case D". Other useful
resin coated magnetic carrier particles include carrier particles
coated with various fluorocarbons such as polytetrafluoroethylene,
polyvinylidene fluoride, and mixtures thereof including copolymers
of vinylidene fluoride and tetrafluoroethylene.
A typical developer composition containing the above-described
toner and a carrier vehicle generally comprises from about 1 to
about 10 percent by weight of particulate toner particles and from
about 90 to about 99 percent by weight carrier particles.
Typically, the carrier particles are larger than the toner
particles. Conventional carrier particles have a particle size on
the order of from about 30 to about 1200 microns, preferably 60-300
microns.
The toner and developer compositions of this invention can be used
in a variety of ways to develop electrostatic charge patterns or
latent images. Such developable charge patterns can be prepared by
a number of means and be carried for example, on a light sensitive
photoconductive element or a non-light sensitive
dielectric-surfaced element such as a receiver sheet. One suitable
development technique involves cascading the developer composition
across the electrostatic charge pattern; while another technique
involves applying toner particles from a magnetic brush. This
latter technique involves the use of a magnetically attractable
carrier vehicle in forming the developer composition. After
imagewise deposition of the toner particles, the image can be fixed
by heating the toner to cause it to fuse to the substrate carrying
the toner. If desired, the unfused image can be transferred to
another support such as a blank sheet of copy paper and then fused
to form a permanent image.
The following examples are included for a further understanding of
the invention.
EXAMPLE 1
A poly(4,4'-isopropylidene diphenyl-alt-ethylene carbonate) resin
as described in Ser. No. 34,557 filed May 4, 1970 is melted on a
rubber compounding mill at a temperature of between
125.degree.-150.degree.C. Cabot Corporation Sterling FT Carbon
Black is added to yield 5.7 parts of carbon black per 100 parts of
polymer. This carbon black-polycarbonate composition is then used
as a control toner. A variety of different materials are then added
to individual samples of the control toner as described below and
then the net toner charge and toner throw-off are measured for each
of the sample toner compositions to test the charge control
capabilities of the various materials added to the toner.
Each toner sample is prepared by blending all ingredients together
on the rubber compounding mill for approximately 20 minutes. Each
melt is then cooled to room temperature and ground in a laboratory
disk grinder to pass through a 20 mesh screen. Final grinding to a
particle size less than 30 microns is accomplished in a fluid
energy mill. The net toner charge is measured by mixing 6 percent
of the toner with an insulating polymer-coated particulate carrier
comprising an oxidized sponge iron core coated with a terpolymer of
acrylonitrile-vinylidene chloride-acrylic acid as described in
McCabe, U.S. Ser. No. 236,765, now U.S. Pat. No. 3,795,617 filed
Mar. 21, 1972, Case B. The mixing is accomplished by placing the
carrier and toner in a small paper cup which is then rolled on a
roll mill for 15 minutes. The net toner charge is measured using a
Faraday Cage in the following manner: a weighed portion of each of
the developers is placed in an iron tube that is covered at one end
with a 200 mesh screen that retains all carrier particles within
the tube. The iron tube is connected in series with a capacitor to
ground. An air stream is then directed through the tube, blowing
toner particles off the carrier, through the 200 mesh screen at the
exit end. The potential resulting on the capacitor is measured by
an electrometer. The potential obtained is converted to electrical
charge in microcoulombs and this figure is divided by the weight in
grams of the toner that is removed from the tube, providing the net
toner charge in microcoulombs per gram.
In addition to net toner charge, a test is devised to measure the
toner throw-off exhibited by each of the sample toners when admixed
with a particulate carrier vehicle as follows: A fixed quantity of
a well-mixed developer (i.e. mixture of toner and carrier
particles) is measured and placed in an open cup positioned in a
device oscillating laterally through a 0.75 inch distance at 6
cycles per second for a fixed period of time. The toner throw-off
of the developer mix due to the oscillation is collected on filter
paper via a vacuum and weighed. The amounts so weighed are reported
in Table I below in milligrams.
TABLE I
__________________________________________________________________________
Concentration (parts/100 Charge Throw-off Charge Agent (outside
invention) parts polycarbonate) (.mu.coul/g) (mg)
__________________________________________________________________________
Control (no charge agent) -- 0.4 350.7 6% cobalt naphthenate
solution 0.5 7.0 73.7 6% cobalt naphthenate solution 1.0 5.6 92.8
6% cobalt naphthenate solution 3.0 6.0 101.5 6% cobalt naphthenate
solution 6.0 5.5 169.6 Heptyldimethylsulfonium bromide (HDSB) 1.0
4.8 110.4 HDSB 3.0 3.5 91.5 Tetrabutylphosphonium bromide (TBPB)
1.0 9.0 39.3 TBPB 3.0 11.2 30.0 Ethylpyridinium chloride (EPC) 1.0
10.3 12.9 EPC 3.0 8.3 22.9 Butylpyridinium chloride (BPC) 1.0 12.6
13.0 BPC 3.0 10.7 Methylquinolinium chloride (MQC) 1.0 10.1 18.6
MQC 3.0 9.0 24.0 MQC 4.5 6.4 32.0 Acetoquat*cetyl trimethyl
ammonium bromide (CTAB) 0.5 8.6 9.7 Acetoquat*CTAB 1.0 9.0 7.9
Acetoquat*CTAB 3.0 8.9 9.0 Acetoquat*cetyl trimethyl ammonium
chloride (CTAC) 0.5 8.4 16.4 Acetoquat*CTAC 1.0 10.2 17.8
Dimethylphenylbenzylammonium chloride (DPBAC) 0.5 2.7 391.8 DPBAC
1.0 3.1 248.8 DPBAC 3.0 6.6 44.1 Triethylbenzylammonium chloride
(TBAC) 0.5 2.3 294.9 TBAC 1.0 1.1 448.5 TBAC 3.0 0.9 159.5
Trimethylphenylammonium chloride (TPAC) 0.5 1.2 21.6 TPAC 1.0 0.3
7.2 TPAC 3.0 -0.9 3.3 Tetraphenylammonium chloride (TPACL) 0.1 10.6
18.3 TPACL 0.3 12.4 14.4 TPACL 0.5 14.3 3.6 TPACL 1.0 13.0 4.2
TPACL 1.5 13.3 1.6 TPACL 3.0 12.5 5.2 TPACL 6.0 7.6 46.4 (Avg)
Tetraheptylammonium chloride (THACL) 0.3 10.1 Not available (N.A.)
THACL 0.5 14.6 N.A. THACL 1.0 11.6 N.A. Tetrapentylammonium
hexafluorophosphate (TPAFP) 0.5 8.9 N.A. TPAFP 1.0 9.8 N.A. TPAFP
2.0 7.9 N.A. Tetraethylammonium benzoate (TEAB) 1.0 11.4 4.0 TEAB
3.0 5.0 45.3 Tetraethylammonium acetate tetrahydrate (TEAAT) 0.5
7.7 2.6 TEAAT 1.0 11.4 3.4 Tetrapentylammonium bromide (TPAB) 0.25
12.2 N.A. TPAB 0.5 15.7 N.A. TPAB 1.0 12.3 3.7 TPAB 3.0 10.1 N.A.
Tetrabutylammonium iodide (TBAI) 0.5 13.5 8.6 TBAI 1.0 10.8 4.1
TBAI 1.5 11.5 4.9 TBAI 3.0 9.9 11.2 Tetrabutylammonium nitrate
(TBAN) 1.0 11.7 4.9 TBAN 3.0 10.2 6.3
__________________________________________________________________________
*Trademark of Aceto Chemical Co., Inc.
EXAMPLE 2
Toners are prepared and tested according to Example 1, except that
a polystyrene resin (Piccolastic D125) is substituted for the
polycarbonate and 6.0 parts of the carbon black are used per 100
parts of polymer. The results obtained are given in Table II.
TABLE II
__________________________________________________________________________
Concentration (parts/100 Charge Throw-off Charge Agent parts
Piccolastic D125) (.mu.coul/g) (mg)
__________________________________________________________________________
Control (no charge agent) -- 2.6 188.5 Tetrapentylammonium chloride
(TPAC) 0.1 6.6 20.7 TPAC 0.5 8.0 16.5
__________________________________________________________________________
These results indicate that the significant effect on charge
obtained with the charge control agents of our invention is
applicable to a variety of polymeric binders and is not restricted
to the use of polycarbonate binders.
Electrophotographic electrostatic charge patterns obtained in the
conventional manner and processed with developer compositions
containing the charge control agents of our invention provide
images that are dense and sharp with little or no coloration, i.e.
deposition of toner particles, in non-image background areas, toner
throw-off or dusting in magnetic brush processes is minimal and the
prints containing the transferred images can be handled repeatedly,
bent, folded and the like without causing undue flake-off of the
image thereon. (See Example 3).
EXAMPLE 3
A toner with one part tetrabutylammonium nitrate and 5.7 parts
Sterling FT carbon black per 100 parts resin is prepared according
to Example 1. The toner is mixed with a magnetic carrier as
described in Example 1 at 6% concentration. This resultant
developer is placed in a magnetic brush of the general type
described in U.S. Pat. No. 3,003,462. An organic
photoconductor-containing element bearing a latent electrostatic
charge image is passed over the magnetic brush. The toned image
thus formed on the photoconductor-containing element is
subsequently transferred to paper. The toned image is fused to
paper with an infrared lamp. Using the above-described developer,
the magnetic brush exhibits low toner throw-off. The images that
are formed are sharp, of high density, and advantageously exhibit
very low background coloration. The images, after fusing, exhibit
good adhesion to paper.
EXAMPLE 4
A toner with 0.5 parts tetrapentylammonium chloride and 5.7 parts
Sterling FT carbon black per 100 parts resin was prepared according
to Example 1. The toner was mixed with a carrier described in
Example 1 at 6% concentration. This resultant developer is placed
in a magnetic brush of the general type described in U.S. Pat. No.
3,003,462. An organic photoconductor-containing element bearing a
latent electrostatic charge image is passed over the magnetic
brush. The toned image thus formed on the photoconductor-containing
element is subsequently transferred to paper. The toned image is
fused to paper with an infrared lamp. Using the above-described
developer, the magnetic brush exhibits low toner throw-off. The
images that are formed are sharp, of high density, and
advantageously exhibit very low background coloration. The images,
after fusing, exhibit good adhesion to paper.
The invention has been described in detail with particular
reference to preferred embodiments thereof, but, it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *