Note: Descriptions are shown in the official language in which they were submitted.
I1~8~9(~ 201,417 CAN/JVL
--1--
Description
ONE-PART TONER POWDER COMPOSITION
Technical Field
This invention relates to dry powder composi-
tions suitable for use in elec~royraphic recording. Moreparticularly, it relates to heat-fusible and pressure-
fixable one part toner powders that have a surface treat-
ment comprisin~ a fluoroaliphatic compound attached to the
surface of the individual toner powder particles.
_ackground Art
One-part toner powder formulations ~sometimes
known as single- or mono-component toners) are known.
They differ Erom two-part or two component developing
powders in that they do no~ utilize a mixture oE carrier
particles and toner powder particles to make up the
developing powder composition. Rather, one-part toner
powders are magnetically responsive and do not utilize a
carrier to develop the electrostatic image.
One-part toner powders may he either heat-
~usible or pressure-Eixable. ~eat-fusible toner powders
are typically fixed after image formation by raising the
temperature of the powders to their melting or softening
point causing the powder particles to coalesce, flow
together and adhere to the substrate. Pressure-fixable
toner powders are typically fixed after image for~ation by
simply applying pressure to the powder particles causing
them to coalesce and adhere to the substrate.
Although both heat-fusible and pressure-ixable
toner powders have been widely used and have enjoyed com-
30 mercial succe~s, they often suffer from certain disadvan-
tages. For example, the images produced wi~h such powders
generally have poor resolution. Thus, they lack sharp
edge definition and openings in the images, such as in the
letters A, a, B, b, D, d, and O, suffer ~rom "fu~zy-fill~
. ., , ' .
~ 1~80g()
-2-
ln" ~i.e., ther~ is slgnificant toner deposited in such
openings ~herebv rendering the~ indistinct). Addition-
ally, there is a substantial deposition oE toner ln
non-image areas, i.e., ~ackground, particularly ~ne areas
5 between letters. Consequently, tne resultant photocopies
are messy in appearance and frequently are difficult to
read.
Additionally, the flow properties and developing
characteristics of such one-part toner powders are o~ten
10 adversely affected by conditions of high humidity. Thus,
they may resist flow, e.g., by caking or forming clumps,
resulting in streaking on the finis~led copy. Such caking
or clumping may also cause clogging in the development
station leading to poor development and transfer of the
toner powder and, consequently, poor copy quality.
The foregoing disadvantages are overcome in the
present invention by surface treating the toner powder
particles with a composition comprising a fluoroaliphatic
compound.
Although the use of fluorochemical materials has
been disclosed previously, see U.S. Patents 3,798,167,
4~002r570j 4,073,~80; 4,139,483, 4,198,477; British Patent
2,034,907; and copending U.S. application serial number
84,607 filed October 15, 1979 and now U.S. Patent
~5 4,268,598, applicant is aware of no disclosure of the use
of a treatment composition comprising a fluoroaliphatic
compound as a surface treatment for a one-part toner
powder.
Of the above-mentioned patents, all except the
British Patent and the copending United States application
disclose the use of fluorochemical materials with two
component developing powder compositions. For example,
U.S. Patent 3,798,167 discloses the application of a
coating of a fluoropolymer, or optionally, a mixture of a
fluoropolymer and a modifying resin, to a carrier
material. U.S. Patent 4,002,570 discloses a three
component developer composition that comprises carrier
1 15809()
particles, toner par~icles) ~nd a lubricant comprising a particulate, cross-
linked polyvinylidene fluoride. The polyvinylidene fluoride particles are said
to lubricate and act as effective photoreceptor cleaning materials. United
States Patent 4,073,980 discloses a two component developing composition wherein
the carrier particles have a mixture of a perfluoroacid and molybdenum disulfide
coated on their surface. United States Patents 4,139,483, and 4,198,477 dis-
close tt~o-part developer compositions wherein a fluorinated surface active
additive is dispersed throughout, rather than coated on, the binder of the
toner portion of the composition.
~luorochemical materials have also been previously utilized
with one-part toner powders. Thus, British Patent 2,034,907 A ~published
June 11, 1980) discloses a toner powder having a magnetic material distributed
throughout a binder resin. A low molecular weight fluorine-containing surface
active agent is applied to the surface of the magnetic material before the
magnetic material is distributed throughout the binder.
Copending United States applica~ion 84,607, filed October
15, 1979, now United States Patent 4,268,598, describes a mixture of a sulfona-
mido surface active material and a toner powder. The resultant mixture has two
discrete components, i.e., the surface active material and the toner powder.
~0 Summary of the Invention
In accordance with one aspect of the present invention, there
is provided a one-part, flowable, dry, electrostatically attractable toner
powder comprising
(a) particles each comprising a blend of from about 30 to 80
parts by weight thermoplastic binder and, correspondingl~ from about 70 to 20
parts b~ weight magnetically responsive material; and
--3-
09(1
~ b) a layer of a surface treatment composition attached to each
of said particles at or near the ou~er surface of said par~icles, said surface
treatment composition comprising from about 0.1 to 2 parts by weight fluoro-
aliphatic compound per 100 parts by weight of said particles.
According to another aspect of the present invention there is
provided a method of electrographic recording comprising: forming a differen-
tial image pattern of a one-part, flowable, dry, electrostatically attractable
toner powder comprising ~a) particles each comprising a blend of from about
30 to 80 parts by weight thermoplastic binder and, correspondingly, from about
70 to 20 parts by weight magnetically responsive material, and ~b) a surface
treatment composition comprising from about 0.1 to 2 parts by weight fluoro-
aliphatic compound per 100 parts by weight of said particles, s~aid surface
treatment composition being attached to the surface of said particles, thereby
adhering said toner powder to said electrostatic image area and thereby develop-
ing said electrostatic image area; and fixing said toner powder by means of
heat, pressure, or heat and pressure.
According to a further aspect of the present invention there is
provided a process of preparing a one-part flowable, dry, electrostatically
attractable toner powder comprising: providing a pluTality of particles each
~0 comprising a blend of from about 30 to 80 parts by weight thermoplastic binder
and, correspondingly, from about 70 to 20 parts by weight magnetically respon-
sive material; providing a surface treatment composition comprising from about
0.1 to 2 parts by weight fluoroaliphatic compound per 100 parts by weight of
said particles; mixing said particles and said surface treatment composition
together at a ten~erature less than the softening point of said thermoplastic
binder for a time sufficient to at least loosely attach said surface treatment
composition to the surface of said particles; heating said particles with at-
P~
1 1~809()
tached surface treatment composition to a temperature of about the glasstransitioll temperature of said thermoplastic binder with continued mixing;
and maintaining said heating with continued mixing ~or a time su~ficient to
substantially permanently attach said surface treatment composition to said
particles as a layer at or near the outer surface of said particles, thereby
providing said toner composition.
The toner powder o the present invention produced ~inal images
with sharply defined edges, substantially reduced "fuzzy fill-in'1, and substan-
tially reduced background, even in the areas between images. The most preferred
toner of the invention virtually eliminates "fuzzy fill-in", and background!
Additionally, the toner of the invention possesses improved flow properties in
high humidity conditions. Thus, it does not significantly cake or clump under
suel~ conditions and the images produced therefrom have sharp edge definition~
e~hibit reduced "fuzzy fill-in", and reduced background.
Still further, the toner powder of the invention tends to be less
sensitive to changes in the size of the developing gap utilized than are the
previously known one-part toners. Thus, there generally is less decrease in
image density as the gap is widened with the instant toners than with such prior
art toners. This permits the use of more generous process conditions and machine
~0 tolerc~nces, such as doctor blade gap, may be relaxed. The toner of the invention
also permits the use of smooth surface developer rolls in place of the more ex-
pensive rough surface developer rolls.
The toner powder of the invention also possessess a less positive
triboelectric characteristic than does a correspondingly non-surface treated
toner powder. It is believed that this property accounts at least in part for
the ability of the developing powder compositions of the invention to provide
such high resolution images.
~4a-
~1~81~
Det~iled Descri~tion of the Invent;on
The po~der of the present invention preferably comprises essen-
tially spherical particles wherein at least 95 number percent of the particles
have a maximum dimension in the range of about 4 to 30 microns. Preferably
-4b-
~, .~ .
- --5--
the particles each comprise a blend of from about 35 to 45
~arts by weight thermoplastic binder, and correspondingly,
from about 65 to 55 parts by weight .~agnetically respon-
sive material. Most pre~erably the particles each com-
prise a homogeneous blend of the binder and magneticallyresponsive material.
The surprising improvements in copy quality
obtained by using the toner powder oE the invention is the
result or treating the surface thereof so that the treat-
ment composition is attached to the surface of theindividual particles. Although the exact mechanism of
attachment is not completely understood, it is believed
that attachment is achieved by at least partially
embedding the mixture into the surface of the particles to
provide a layer or zone of the treatment around the
particles.
The fluoroaliphatic compound useful as the
surface treatment composition may be monomeric or
polymeric and, preferably, contains in the same molecule
both a fluoroaliphatic group and a group which may contain
an aliphatic group, an aromatic group, or both and which
is attracted to the thermoplastic binder used in the toner
powder of the invention. The particular structure of the
fluoroaliphatic compound is not critical to the invention.
However, the preferred fluoroaliphatic compound may be
represented as RfQm2 where R~ is a fluoroaliphatic group,
~m is a linking group, and Z is a terminal group.
The fluoroaliphatic group, may be generally
described as a fluorinated, monovalent, non-aromatic group
3 of at least 3 carbon atoms. The alphatic chain may be
saturated, unsaturated, straight, branched, or, if
sufficiently large, cyclic and may include oxygen or
trivalent nitrogen atoms bonded only to carbon atoms. A
fully luorinated group is preferred, but hydrogen or
chlorine atoms may be present as .substituents provided
that not more than one atom of either is present for every
two carbon atoms, and preferably, the group contains at
` 11~80~()
--6--
least a terminal perfluoromethyl group. While fluoro-
aliphatic groups containing a larger number of carbon
atoms will function adequately, tho~e containing not more
~han about 20 car~on a~oms are preferLed since larger
groups usually represent a less efficient utilization of
fluorine than is possible with shorter chains. Fluoro-
aliphatic groups containing about 5 to 12 carbon atoms are
most preferred.
In the linking group Qm~ m is an integer ~rom 0
to 2, and Q represents a direct bond between Rf and Z when
m is zero, or a multifunctional, generally difunctional,
linking group such as alkylene, arylene, sulfonamido
alkylene, carbonamido alkylene and the like. In some
instances more than one R~ group may attach to a single Q
group and in other instances, a single Rf group may be
linked to more than one Q group, or may be linked by a
single Q group to more than one Z group.
The Z groùp represen~s an anionic, a cationic, a
non-ionic or an ampholytic moiety or combinations thereof.
Typical anionic groups would include -CO2M, -SO2M~ -SO3~,
-OPOOM, and -OP(OM)2, where M is hydrogen or a metallic
ion, such as sodium, potassium, calcium, etc. Typical
cationic groups would include -NH2, -NHR, where R is a
lower alkyl group such as methyl, ethyl or butyl, -NR3~A~,
where Rl is a lower alkyl group or hydrogen and A is an
anion, such as iodide, chloride, sulphate, phosphate,
hydride, etc. Typical non-ionic groups would include
-NR2-~0 and those derived from polyethylene oxide and
mixed polye~hylene oxide-polypropylene oxide polyols.
3 Typical mixed or ampholytic groups would include
-N(C2H4OH)2~ -N~C2H4NHC2H4NH2~ -N(cH3)2c2H
-N(CH3)(C2H4CO2H)2 -~ O, and the like.
Specific examples of useful ~luoroaliphatic
compounds include
CH3
C8F17Sa2N ( C2H5 ) C2H40CoNH~$1
C8F17S2N ~ C2H5 ) C2H40CONH
., ~
~ 1580g()
--7---
~C8~l7so?NHc3Hs~(cH3)3)I3
C8~17S2N(C~3)H
C8F17S2N ( C2H5 ) CH2COOH
C8F17S3K
Cg~l7SO2NHC2H4NHC2H4NH2
(cgFl7so2N(c~Hs)c2H4o)2pooH
C8Fl7so2w(c2Hs)c2H~opo(oH)2
Other specific examples of useful
fluoroaliphatic compounds include
CF3C(C2Fs)2C(CF3)-C(CF3)O - ~ SO3M
where M is as described above, available as "MD 31" from
ICI, Ltd.,
(CaF2a+1C2H4O)2P(o)(ONH~), where a is an integer of from
A about 5-25, available as "Zony ~ FSP from E. I. duPont
deNemours), and
CaF2a+lC2H4SCIHCOOM
CH2COOM,~where a and M are as described above
available as "Lodyne~ S100 from Ciba-Geigy.
Polymeric fluoroaliphatic compounds are also
useful in the invention. For example, the copolymer (95/5
by weight) of CgF17SO2N(C2Hs)C2HsOCOC(CH3~-CH2 and
butylacrylate is a useful surface treatment material.
Fluoroaliphatic compounds and methods for their
preparation are further described in, for example, United
States Patents, 2,559,751; 2,559,749, 2,559,754;
2,559,629; 2,597,702; 2,732,398; 2,759,019; 2,803,615;
f~,o~e ~)~1L
1 lssosn
8--
2,80~,999; ~,915,554; 3,129,254; 3,282,905; 3,39~,182;
3,911,0So; 4,171,282; British Speciications 1,270,662,
1,130,822, and Organic Fluorine Chemis~ry, L~lilas Hudlicky,
Plenum Press, ~.Y. (1971).
The fluoroaliphatic compound is preferably
blended with one or more other ingredients before being
applied to the surface of the particles. Thus, the
surface treatment may further comprise from about 0.1 to
2.5, preferably 0.5 to 2.5, parts by weight silicon
dioxide per 100 parts by weight particles; from about 0.1
to 2, preferably 0.5 to 1, parts by weight carbon per 100
parts by weight particles; or both.
~lost preferably the treatment composition
comprises a mixture of said fluoroaliphatic compound, said
silicon dioxide, and said carbon. In ~his instance the
treatment composition preferably comprises from about 0.
to 1 part by weight silicon dioxide, 0.4 to 0.7 part by
weight fluoroaliphatic compound, and 0.7 to 0.8 part by
weight carbon per 100 parts by weight particles when
heat-fusing toners are made; and from about 1 to 2.5 parts
by weight silicon dioxide, 0.6 to 1.2 parts by weight
fluoroaliphatic compound, and 0.7 to 0.8 part by weight
carbon per 100 parts by weight particles when pressure-
fixing toners are made.
The silicon dioxide useful in the surface treat-
ment comprises a powder having an average particle size
(i.e., average diameter) smaller than that of the toner
powder particles but whose exact size is otherwise not
critical to the invention. Preferably the silicon dioxide
is a pyrogenic silica in the form of spherical particles
having an average diameter in the range of 5 to 50 milli-
microns (most preferably in the range of 10 to 20 milli-
microns).
Silicon dioxide particles per se are known and
may be prepared by, for example, the hydrolysis o~ silicon
tetrachloride in an oxygen-hydrogen flame. Py~ogenic
silicon dioxide is hydrophilic as prepared. However, it
~ 1~809~
g
can be rendered hydrophobic, if desired, by reacting the
silanol groues on tne particle surface with chlorosilane.
E~amples of use~ul silicon dioxides include
"~erosil~" 20C (a hydrophilic, pyrogenic, white fluffy
powder, 99.8% SiO~, average primary particle si~e o, 12
millimicron, bulk density of 200 m2/g, and BET surface
area of ~00 ~ 25 m2/G), and "AerosilO" R972 (a hydro-
phobic, pyrogenic, white fluffy powder, 98.3% SiO2,
average primary particle size of 16 millimicron, bulk
density of 60 g/1, and BET surface area of 120 ~ 20 m2/g).
These materials are available from Degussa, Incorporated.
The carbon useful in the surface treatment i5
also a powder whose average particle size (i.e., average
diameter~ is smaller than that of the toner powder
particles but whose exact size is otherwise not critical
to the invention. Particularly useful carbons have an
average diameter below about lO0 millimicrons and
preferably one below about 40 millimicrons. It is also
preferred that the carbon be conductive, i.e., that it
have a static electrical conductivity of at least 10-2
reciprocal ohm-cm in a 10,000 v/cm electrical ield.
Static electrical conductivity may be measured as
described in U.S. Patent 3,639,245 at column 3, line 47 -
column 6, line 46.
E~amples of useful carbon materials include
A carbon blacks such as "Vulcan~ XC-72R, a conductive carbon
black with a maximum particle size of 30 millimicron sold
by Cabot Corporation; "Conducte~" 9S0, maximum particle
si~e of 21 millimicron sold by Cities Service; "Rave
1800, maximum particle size of 1~ millimicron sold by
Columbia ~hemicals; "Ketjenblackr' EC sold by Noury; and
"Thermax" MT sold by R. T. Vanderbilt.
When a conductive carbon is employed in the
surface treatment, the resulting ton~r powder preferably
has a dynamic conductivity in the range of 2-15 (most
preferably 6-9) microamperes (~A) in an electric field of
1,000 D.C. volts. The dynamic conductivity referred to
t~d~e ~
..
t 1580g()
--10--
here is measured according to the technique described
hereinafter.
~ he thermoplastic binder useful in the present
inven~io~ may be any thermoplastic material although
or~anic materials are preferred. ~ost preferably the
binder is selected from the group consisting of ~a) waxes
that have a melting point in the range of 45C to 150C as
measured according to ASTM:D-127, (b) organic resins that
have a ring and ball softening point above about 60C as
measured according to AST~:E-128, and mixtures of the two.
Waxes useful in the binder include aliphatic
waxes (e.g., natural or synthetic), fatty acids and
derivatives thereof, metal salts of fatty acids,
hydroxylated fatty acids or amides, low molecular weight
ethylene homopolymers, or mixtures of such materials.
Other useful waxes include aromatic and polymeric wax~ e
materials.
Representative examples of useful aliphatic
waxes include paraffin wax, microcrystalline wax,
caranauba wax, montan wax, ouricury wax, ceresin wax,
candellila wax, and sugar cane wax. Representative
examples of useful fatty acids include stearic acid,
palmitic acid, and behenic acid. Representative examples
of useful metal salts of fatty acids include aluminum
stearate, lead stearate, barium stearate, magnesium
stearate, zinc stearate, lithium stearate, and zinc
palmitate. Representative examples of useful fatty acid
derivatives include castor wax (glyceryl tris-12-hydroxy
stearate), methyl hydroxystearate (commercially avaiIable
A 30 under the trade name "Paracin~l"), ethylene glycol
monohydroxy stearate (commercially availabIe under the
trade name ~Paracin 15"), and hydroxystearic acid.
Representative examples of useful hydroxylated fatty acids
or amides include N(betahydroxyethyl)ricinoleamide
(commercially available under the trade name "Flexricin
115"), N,N'ethylene-bis-ricinoleamide (commercially
available under the trade name "Flexricin 185"),
L158~
N(2-hydroxylethyl)~12-hydroxystearami~e (commercially
available under the trade name "Paracin 220"), and
N,N'-ethylene-bis-12-hydroxystearamide (commercially
available under ~h~ trade name "Paracin 285").
Representative examples of ethylene homopolymers include
the low molecular weight polvyethylenes such as the Bareco
"Polywaxes", e.g., "Polywax~ 655, 1000, and 2000 sold by
the Bareco Division of Petrolite Corporation. Other
~thylene homopolymers include oxidized, high density, low
molecular weight polyethylenes such as "Polywax" E-2018
and E-2020 sold by Bar~eco Division oE Petrolite Corpora-
tion, and the "Epolene~' series of low molecular weight
polyethylene resins such as "Epolene" E-14 available ~rom
Eastman Chemical Products Incorporated. Representative
examples of useful aromatic wax-lilce materials include
dicyclohexylphthalate, diphenylphthalate and the "Be
S~uar~ series of waxes from thè Bareco Division of
Petrolite Corporation, such as "Be Square" 195. The "8e~
Square" waxes are high melting point waxes that consist of
paraffins and napthenic hydrocarbons.
Representative organic resins useful as the
thermoplastic binder are polyamides, polystyrenes (e.g.,
2000 mol. wt.); epoxy resins (e.g.l diglycidyl ether of
bisphenol-A such as "Epon~' 1004, commercially available
~5 from Shel~ Chemical Corp); acrylic resins (e.g.,
"Elvacite 2044, and N-butyl methacrylate commercially
available from E. I. duPont deNemours); vinyl resins such
as polyvinyl butyral (e.g., "~utva~" ~72-A, commercially
available fro~ Monsanto Company), polyvinyl acetate resins
3 ~e.g., "Gelva~' V-100, commercially available from Monsanto
Company); vinyl copo~ymers such as vinyl chloride/vinyl
acetate (e.g., "VY~H', commercially available from Union
Carbide Corp.), ethylene/vinyl acetate copolymersi
cellulose esters such as cellulose acetate butyrate (e.g.,
nEAB-171-25", commercialiy available from Eastman Ch~mical
Products, Inc.), cellulose acetate propionate; and
cellulose ethers.
t~
11~8~gn
-12-
When a heat-fusible developing powder is
desired, the thermopla~tic binder preferably comprises the
organic resin. Most preferably the organic resin is an
epoxy resin. However, some wax may also be incorporated
into the binder of a heat-fusible toner powder. The wax
is added to reduce the temperature necessary to achieve
satisfactory fusing of the toner to a desired surface.
Typically the weight ratio of the organic resin to the wax
is between about 4:1 and 20:1.
When a pressure fixable developing powder is
prepared, the thermoplastic binder comprises either the
wax alone or a combination of the wax and the organic
resin. When the binder comprises said combination~ the
weight ratio of wax to organic resin is between about 1:1
to 50:1, preferably between about 4:1 and 20:1. Most
preferably the binder consists essentially of the wax. In
either event, the wax preferably is selected from micro-
crystalline wax, low molecular weigh~ polyethylene resin,
or a combination thereof, while the organic resin, when
present, comprises an epoxy resin.
The magnetically responsive material employed in
the developing powder composition preferably is homo-
geneously distributed throughout the binder. Addition-
ally, it preferably has an average major dimension of one
micron or less. Representative examples of useful
magnetically responsive materials include magnetite,
barium ~errite, nickel zinc ferrite, chromium ox~de,
nickel oxide, etc.
Other binders useful for pressure-fixable ton~r
powders are known. Thus, for example, see U. S. Patent
3,965,022. This patent describes a binder that comprises
(a) about 74 to 98 parts by volume of a thermoplastic
component that has a softening point of at least about
60C, a 10-second shear creep compliance in the range of
about 1 x 10-9 cm2/dyne to 1 x 10-13 cm2/dyne at room
temperature, and a "heat deflection temperature" below
about 300C, and (b) about 2 to 26 parts by volume of a
5 8 ~
-13-
non-volatile component having a principal glass transition
temperature below about 0C as measured by differential
thermal analysis, and a 10-second shear creep compliance
in the range of about 50 cm2/dyne to 8 x 10 8 cm2/dyne
at room temperature, said non-volatile component preferably
being elastomeric.
Examples of useful -thermoplastic components
(i.e., low shear creep compliance materials) and of
non-volatile components (i.e., high shear creep compliance
materials) are disclosed in U.S. 3,965,022.
Other ingredients may be incorporated onto the
particles used in the toner powder of the invention.
Thus, fatty acid amides containing at least about 10
carbon atoms have been found to be useful in reducing the
time required to prepare the toner powders. Typically
from about 0.05 to 2~ ~y weight of the fatty acid amide
is satisfactory. Examples of useful fatty acid amides
include erucamide, stearamide, behenamide, oleamide,
N,N'-ethylene-bis(tall oil)amide, and N,N'-ethylene-bis-
oleamide.
The developing powders of the invention may be
readily prepared. Thus, a dry blend of the thermoplastic
binder and the magnetically responsive material is obtained
by melting the thermoplastic binder, stirring in
the magnetically responsive material, preferably until
a homogeneous mixture is provided, allowing the mixture
to cool, grinding the mixture to form particles, and
classifying the resulting solid particles to the desired
si2e (i.e., 1 to 40 microns maximum dimension).
The particles, which are irregularly shaped,
are then preferably formed into "prespheres" by first
aspirating them into a moving gas stream, preferably air,
thus creating an aerosol, and directing the aerosol at
an angle of about 90 * 5 through a stream of gas, again
preferably air, which has been heated to about 450C and
1 ~580~n
-14-
600C into a cooling chamber where the now substantially
spherical particles settle by gravity as they cool.
The surface treatment composition is then
applied to the "prespheres". ~hen the ~reattnent composi-
tion contains ingredients (e.g., silicon dioxide and/orcarbon) other than the fluoroaliphatic compound, a mixture
of the ingredients is first prepared by charging them to,
for example, a "Warin~" blender and mixing for about
one-half hour at a medium speed. The resulting preferably
homogeneous mixture is fluffy and black.
The prespheres and surface treatment composition
are then each added to a blenvder te.g., a twin shell
blender Erom "Patterson Kell~") and cold blended a
temperature less than the softening point of the thermo-
plastic binder (e.g., 2~-30C) until the surface treatment
is at least loosely adhered to the prespheres. Typically
this is accomplished within three hours. I~ desired, the
prespheres may be cold blended with one of the above
disclosed fatty acid amides before treating the prespheres
with the surface treatment composition.
In either event, the treated prespheres are then
"hot7' blended at about the glass transition tamperature of
the thermoplastic binder for a time sufficient to
substantially permanently attach the treatment composition
~5 to the particles. This is typically accomplished in from
two to six hours. Preferably the surface treatment
composition is attached as a layer or ~one at or near the
surface of the prespheres.
After hot blending, the resultant toner powder
is cooled for about one half hour, screened to remove
agglomerates, and classified so that 95% by weight of the
product is greater than 4 microns average diameter and
only 5% by weight is greater than 30 microns average
diameter.
The toner powder of the invention is useful in
electrographic recording processes where a differential
image pattern of the toner is formed and subsequently
,~ P ,6~
1 1~80~n
15-
fixed by means oE pressure, heat, or heat and pressure.
The diferential image pat~ern may be formed by, for
example, forming electrostatic image areas on a photocon-
ductive surface ad contacting the image areas with the
toner. Alternatively, the differential image pat~ern may
be formed by contacting a passive dielectric su~face with
the toner; forming the image pattern by, for example,
selectively exposing the uniformly toned surface to a
stylus which imagewise transmits an electrical potential
signal; and magnetically removing toner from uncharged
areas. See U.S. Patent 3,816,840 for further description
of this process. If desired, the toned image areas may be
transferred to another surface prior to fixing.
The present invention is further illustrated by
means of the following examples wherein the term "parts"
refers to parts by weight unless otherwise indicated.
In these examples, several physical character-
istics of the toner powders were measured. The techniques
for measuring these characteristics are described below.
a. Dynamic Conductivity.
This property simulates the electrical
conductivity of a toner powder when used in an electro-
static copying process. Dynamic conductivity is measured
on a test rig t~ at comprises the developing station o~ a
A 25 "Secretary III photocopier (available from the 3M
Company) except that the photoconductor drum is replaced
by an aluminum drum (12.5 cm dia). The developer roll
comprises a stainless steel shell (3.15 cm dia) around an
8 pole circular magnet. ~ doctor blade, a toner hopper,
and a lO00 volt power supply are also supplied. The gap
between the developer roll and the aluminum drum is set at
0.071 cm, the gap between the doctor blade and the toner
hopper at 0.05 cm; and the gap between the toner hopper
and the developer roll at 0.125 cm.
To measure conductivity, 16 ml of toner is
charged to the hopper, and the test rig is started so that
the developer roll and the aluminum drum are driven in
f~Zd J~
1 1~8U9()
--16--
opposing directions with tne developer roll having a
sur'ace speed of 61.3 cm/sec and the aluminum drum having
a surface speed of 19.5 cm/sec. The test rig is then run
for five minutes aft~r which the current passing through
toner is measured while the toner is in the development
gap and under a 1000 volt potential.
b. ~aximum Dengity (Dmax)
This property illustrates the optical output
density of an image produced from an original having an
optical input density of one. Preferably DmaX is at least
one.
~ max is measured by determining the diffuse
reflection optical density of the image using a conven-
tional diffuse reflection densitometer (e.g., Mac~eth
Quanta-Log Diffuse Reflection Densitometer, Model RD-100).
The optical density reading is taken as the DmaX for the
toner powder being tested.
c. Density Decay.
This property measures the sensitivity of a
toner powder to changes in the size of the development
gap. Generally speaking, the density of an image produced
from a given toner powder decreases as the siæe of the
development gap increases. Thus the larger the gap, the
lower the resultant image density. Larger decreases
indicate that the toner powder is more sensitive to such
changes and, therefore, requires narrower development
gaps.
Density decay is measured on a conventional
electrographic recording device (e.g., a "Secretary III")
as follows. The development gap is reduced to the point
at which image densities on an imaged and developed
photoconductive surface vary from bands of high and low
image density horizontally across said photoconductive
surface. The development gap is then opened by turning
the adjustment means two full turns from this point. A
copy is produced at this opening and its image density
measured using a conventional diffuse reflection densi-
0~1~
-17-
tometer such as is set Eorth above. The development gap
is then ~urther opened by turning the adjustment means
~our additional (to~al o~ six) turns ~rom said point. A
copy is produced at this opening and its image density
measured as described above~ The density decay i3 taken
as the decrease in image density from the narrower ko the
wider o the two development gaps.
d. Contrast (Gamma).
This property is a measure of a toner powder's
ability to distinguish between dif~ering image densities
on an original and reproduce those differences on a copy.
High contrast values, i.e., greater than 5, indicate the
toner powder's inability to distinguish and reproduce the
difference between varying image densities.
Contrast is measured according to the following
procedure. Copies of an original haviny a range of image
densities (i.e., a step wedge) are made on an electro-
graphic recording (e.g., a "Secretary III") machine. The
output image densities are measured as described above in
the DmaX test and plotted against the loglo of the input
image densities. The loglo of the input densities are
plotted as the horizontal axis and the output densities
are plotted as the vertical axis. The contrast (gamma) is
taken as the slope of the straight line portion of the
plot.
Examples 1-16
A series of examples of heat fusible toner
powders were prepared. In the examples, 95% by weight of
the toner powders were greater than 5 microns average
diameter and only 5% by weight were greater than 22
microns average diameter. Examples 1-15 were examples of
the invention while Example 16 was a toner powder that was
not surface treated.
In each example the prespheres were prepared as
described above from 40 parts epoxy resin ("Epon" 1004
~rom Shell Chemical Company) and 60 parts magnetite.
~ ~8~
-18-
Examples l-i~ the prespheres were separately surface
treated as described above using different treatment
cvmpositions. In example 15 the surface traatment
composition ~as cold blended with the prespheres for 15
5 hours prior to hot blending.
The following treatment compositions, with
quantities reported as parts, were used:
o~n
--19--
~O
O l l l I . l l l l l l l I
O l l l l l l l l
~ CO
Z I I I I . I I I I . I I I
O l l l l O
CO
I I I I I I I . . I I
O O
~ 1 1 1 1 1 1 1 . I . I . I
O l O l O
r
X I I I I I I . I I . I . I
o I I o I o
I I I I I I I I . .
I o I I I I o o
H ~ r
o I I I I I I o
I I I I o I I I I I o I o
~D CO r--
I I I . I I I I I. .
o I I I I Io o
~D CO r~
~ I I II o ~ I I I o I I o
E~ ~I I II . I I I I . I . I
H l l ll O l l l l O l O
U~
~D CO r-
~ C~I I I I I I I I . I . I
o I I IO I I I I I O I O I
c~ ~O a) r
~ I I ~I I I I I I ~ I .
E~ I I OI I I I I I o I o
U~ CO
alI . II I I I ~ I . I .
o I II I I I I o I o
~r; ~ . I I I I I I I I . I .
E~o I I I I I I I I o I o I
o
CD C ~ [~1 u
O ~
^ o o
O O ~ ~ O :~: Z
4 o o U
O O :C er o o _ _.
~r ~r ~ m ~ v -- C)
m 5 ~ ~ O U ~
_ _ ~9 In _ _ 5 ~~4 0 ~
~ ~ O ~ ~ S:: Z O = t-- ~
-- -- æ z -- -- -- ~ _ o
z ~; ~ ~ z æ z Y ~
o o U~ U~ o o o o + ~I ~ ~ ~
r r ,1 ,~ r r r r ~ c -- u~ I o o ~ ~
r~ ~ ~ r~ r~ ~ ~I ~ o t~ r~ ~
cr~ ~o ~ ~ ~ ~ 0 ~ ~ ~ O
O
~1 ~I N
,
1 1 ~ 8 ~
~20-
The non-surace treated toner powder (Example
1~) was prepared by combining 100 parts o~ the prespheres
with 0.6 parts o~ conductive carbon black (Vulcan XC-72R
Erom tAe Cabot Corporation) to form a mixture. The
mixture was dry blended at room temperature ~or 3 hours
and then hot blended at 65C for about 8 hours. The
carbon was then embedded into the prespheres as a layer or
~one at or near the surEace thereof by drawing the
particles of the mixture into an air stream at a rate of
36 kg/hr to form an aerosol; directing the aerosol at
90 + 5 into a hot (650C) air stream; allowing the
powder to settle; and collectiny the powder by filtration.
About 0.05% by weight SiO2 ("Aerosil" 372, Degussa,
Incorporated) was blended with the toner as a separate
component to aid its flow properties.
The powders were then used in a heat-fusing
copying process in a "Secretary III" copying machine
(available from the 3M Company) to provide images on plain
paper substrates. The exposure vol~ages are reported in
Table 1. The bias voltage was set at -200 DC volts.
The ~urface treatment compositions employed
together with the results obtained (i.e., dynamic
conductivity of the toner powders, the maximum density
(DmaX)~ the density decay, and the image contrast) are
given in Table 1.
1 1580~1
-21
~1
o o ~ o ~ ~ a~ O Ll~
C ~ ~ ~ ~ ~ ~ ~ r~- ~ ~ ~1 ~`3
o
c a~ ~ ~ ~ ~ ~ ~ ~ ~ '`.
a o o O O O O O O O O O O O O O O
O ~ _I ~ ~ ~ ~ ~ ~1 ~ O O O
~ ~1 0 ~/ ~1 ~ ~1 ~ ~1 ~ ~ ~1 ~ ~1 ~1 0 --
t)
.~, .~, ~
_1 ~ ~ O a~ 1 ~ 1` d' O a ~ ~ r~, o l~ ~r
~ a c ~
~: o -~ .
O ~ r~ In ~ ~ O~ 1-- ~ O ~ ~ O ~ I~ a~
o
~
; O
., C
E~ O
aJ
,~
L~ o U~ o
~ ~1 ~
1 1~8~9n
-22-
The toner powders of the invention, i.e., those
used in Examples 1-15 provided copies with images that
were more sharply defined than were the images provided by
,he toner us~d in Example 16. T'nus the edges o~ the
images produced in Examples 1-15 were sharp, ~he openings
in the images (letters) had substantially reduced "fuzzy
fill-in", and the spaces between the images (background)
had substantially reduced blurring caused by undesired
toner deposition. Furthermore, the toners used in
Examples 1, 2, 7, and 13 produced copies having virtually
no "fuzzy fill-in" and virtually no background. The
images produced from the toner used in Example 1~,
however, had blurry edges, substantial "fuzæy fill-in",
and substantial ~ackground.
Additionally, the toners of the invention
generally demonstrated less density decay than did the
non-surface treated toner used in Example 16. Thus, the
toners of the invention generally permit the use of less
stringent process conditions such as yap latitude.
The foregoing results are achieved without
adversely affecting other physical characteristics of the
toner powders. Thus, dynamic conductivity, Dma~, and
contrast all remain within acceptable limits.
EXAMPLE 17
A pressure-fixable toner powder according to the
invention was prepared as described above except that the
prespheres were prepared Erom 10 parts "Polywax" 1000 (a
low molecular weight, unmodified homopolymer of ethylene
having a Mw/Mm of 1.2 from Bareco Division of Petrolite
3 Corporation), 30 parts "Epolene" E-14 (an emulsifiable low
molecular weight polyethylene resin from Eastman Chemical
Products, Incorporated), and 60 parts Magnetite.
The prespheres were surface treated as described
above with a treatment composition comprising 0.6 parts
nVulcan" XC-72R, 2.4 parts "Aerosil" 200~ and 1.2 parts
C8F17S2N(C2Hs)CH~CH-
l ~80g(1
-23-
The resulting toner powder ~as used in a cold(room temperature) pr~ssure-fixing copying process to
provide images on a plain paper substrate. The exposure
voltage was ~ volts. The images on the copie~ produced
5 were sharp, the openings in the images had virtually no
"fuzzy fill-in", and there was virtually no background.
The toner powder had a dynamic conduc~ivity of
5.3 A/103V, a Dma~ f 1.47, and a contrast (gamma) of 4.3.
EXAMPLE 18
A heat-fusible toner powder according to the
invention was prepared as described in Examples 1-14
utilizing the following surface treatment composition:
CgF17SO2NHC2~4~HC2~4NH2 0.6 parts
"Aerosil" 200 0.8 parts
"Vulcan" XC-72R 0.7 parts
The resulting toner powder was used in a heat-
fusing copying process in a "Secretary" III copying
machine to provide images on plain paper substrates. The
exposure voltage was 75 volts and the bias voltage was 200
volts.
The images on the resultant copy were sharply
defined, had virtually no "fuzzy fill-in", and the copy
had virtually no background. Additionally, the toner
powder had a dynamic conductivity of 9.5 A/103V and
produced images having a DmaX f 0.62 and a contrast of
0.65. While the DmaX and contrast values of this example
are low, it still demonstrates improved edge sharpness,
"fuzzy fill-in" and background.
EXAMPLE 19
A heat fusible toner according to the invention
was prepared as described in Examples 1-14 except that the
surface treatment composition was prepared by the
following procedure.
A dispersion of a polymeric fluoroaliphatic
- 35 compound in solvent was provided. The fluoroaliphatic
Og()
~4-
compound was a 95/5 by weight copolymer of
C8F17SO2N(C2H5~C2H4OCOC(CH3)=CH2 and butyl acrylate.
Sufficient methyl alcohol was added to the dispersion to
~recipi.at2 the pGlymer. The polymer was dried in a
vacuum oven. The fluoroaliphatic compound was then ground
with a mortar and pestle to reduce it to a relatively fine
powder.
The surface treatment composition was then pre-
pared as described above by combining 0.6 part fluoro-
chemical, 0.8 part "Aerosil" 200, and 0.7 part "Vulcan"XC-72 R.
The resulting toner powder was used in a heat-
fusing copying process in a "Secretary" III copying
machine to provide images on plain paper substrate. The
exposure voltage was 78 volts and the bias voltage was 200
volts.
The images on on the resultant copy were sharply
defined, had virtually no "fuzzy fill-in", and the copy
had virtually no background. Additionally, the toner
powder had a dynamic conductivity of 8~A/103V and produced
images having a DmaX of 0.98 and a contrast of 1.53.
