Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to toner powder for the development
of latent electrostatic images. The invention relates in particular to a
toner powder which can be charged positively and substantially consists of
finely divided, coloured toner particles containing an insulating thermoplas-
tic resin, colouring materials and a polarity control agent. The present
invention also relates to a process for preparing such a toner powder and to
a two-component developer containing such a toner powder.
In electrophotography, latent electrostatic images are formed on a
suitable surface. To make these images visible, powder developers of the
so called two-component type are widely used. These are developers containing
fine, black or otherwise coloured toner particles and comparatively big
carrier particles. Upon contact with or friction against the carrier particles
the toner particles have an electrostatic charge, and as a result they adhere
to the carrier particles. In general, the composition of toner and carrier
particles is chosen such that the toner particles accept a charge of a polar-
ity opposite to that of the latent electrostatic image to be developed. When
the toner powder is brought into contact with this image, the toner particles
are released from the carrier particles by the electrostatic charge of the
image, and`are deposited on the latent image, as a result of which this be-
comes visible. In direct electrophotography the powder image is generally
fixed by heat onto the surface on which it has been deposited. In indirect
electrophotography the powder image is transferred to a receiving surface and
fixed thereon. Heating mostly occurs by radiant heat, in a so-called radia-
tion fusing device, or by bringing the powder image in a so-called contact-
fusing device into contact with a heated surface, such as a roller and/or a
belt, a combination of heat and pressure fixing thus being effected The two-
component powder developers may contain, as carrier particles, powdered mat-
erials of widely varying composition, They may consist, for example, of metal,
e.g. iron or nickel, metallic oxide, e,g. chromium oxide or alwninium oxide,
glass, sand or quart7. Metal carrier particles, especially iron particles,
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are frequently used in practice. ~n particular iron particles are frequently
used in powder developers for use in the so-called magnetic brush development,
in which technique the developer is carried by magnetic transport means to
the electrostatic image to be developed.
The toner particles in the two~component powder developers sub-
stantially consist of an insulating, thermoplastic resin, or a mixture of such
resins, and one or ~ore colouring materials. The conventional natural and
synthetic polymers are used as thermoplastic resins. Examples of thermoplastic
resins, which are extensively used, are poiystyrene, copolymers of styrene
with an acrylate and/or, methacrylate, polyamides, modified phenolformaldehyde
resins~ polyester resins and epoxy resins. Carbon black is generally added
as colouring material in black toner powders, and in coloured toner powders
employed, for example, in electrophotographic multi-colour reproduction pro-
cesses, organic dyes are added to the thermoplastic resin.
Generally, the above-mentioned resins themselves cannot be charged
positively to a sufficient extent. Most of them are charged negatively upon
contact with iron particles. Thus, the addition of a polarity control agent,
i.e. an agent making the triboelectric charge sufficiently positive, is re- ;
quired if a positively chargeable two-component powder developer suitable for
ZO magnetic brush development is desired. Polarity control agents that have
proved effective include amino compounds, quaternary ammonium compounds and
organic dyes, in particular basic dyes and their salts, such as the hydro-
chlorides. Examples of conventional polarity control agents are benzyl,
dimethyl-hexadecyl ammonium chloride and decyl-trimethyl ammonium chloride,
nigrosine base, nigrosine hydrochloride, Safranine T and Crystal Violet.
Especially nigrosine base and nigrosine hydrochloride are often used as polar-
ity control agent. ~ ;
The basic requirements which a toner powder in general, and a posi-
tively chargeable toner powder in particular must meet, are pronounced polar-
ity, good charging characteristics such as sufficient chargeability, uniform
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charge distribution, charge stability and low sensitivity to moisture andtemperature, good fusing properties that are also properly reproducible,
thermal stability and a good permanence during prolonged use. ~loreover, for
a toner powder to be used in an electrocopier with a contact-fusing device
the fusing range should desirably be as broad as possible. Por use in a
copying apparatus with a radiation fusing device the fusing range should pre-
ferably be as small as possible.
Though a number of the negatively chargeabl~ toner powders proposed
hitherto satisfy the above-mentioned properties to a fair degree, with the
positively chargeable toner powders this is the case to a far lesser degree.
This can be said in particular of their charge stability, reproducibility of
the fusing properties, thermal stability and, especially, of their uniform
chargeability and permanence. To obtain uniform chargeability with a good
permanence of the toner particles, the polarity control agent must be distri-
buted fully homogeneously throughout the resin. As is well known, toner pow-
ders are generally prepared by means of the so-called kneading method, the
extrusion method or the hot melt method. In these processes, the resin is
homogeneously mixed in a molten state with the colouring materials, the polar-
ity control agent and, if desired, other ingredients. After cooling down the
2~ solid mass so obtained is ground to particles of the desired degree of fine-
ness, and all these particles must have exactly the same composition, in order
to get a toner powder by which a good image quality can be obtained. However,
the positive acting polarity control agents whlch are preferably used often
do not or only sparingly dissolve in the the~moplastic resins or mixtures of
resins to be used for the toner powders, as a result of which the desired
homogeneity cannot be obtained. This can be said in particular of the highly
preferred nigrosine base and nigrosine hydrochloride.
In the ~ew cases where there are positive acting polarity control
agents that, for the purpose intended, do dissolve sufficiently in the thermo-
3~ plastic resin, as is the case with polyamides, e.g , the resin itself has
several not quite favourable yroperties, as a result of which toner yowdersprepared on that basis do not fulfill very well the aforementioned basic pro-
perties such as, for examyle, the sensitivity of the charye to moisture and
temperature.
I'he object of the present invention is to provide a positively
chargeable toner powder which in general meets the afore-mentioned ~asic
requirements and, in particular, largely meets the requirements that proved
hard to be realized, especially for positively chargeable toner powders, in
respect of uniform chargeability, charge stability and permanence, reproduci-
bllity of the fusing properties, thermal stability c~nd sensitivity to mois-
ture. A further object is -to provide a method by which the toner powder
according to the invention can be manufactured tailor-made in a simple and
economic way.
The present invention provides a positively chargeable toner
powder characterized by stability at temperatures up to 50C and a melting
point of about 65 to 150C, which comprises finely divided toner particles
containing an insulating thermoplastic resin, colouring materials, and a
polarity control agent, the thermoplastic resin including at least 50% by
weight of a modified epoxy resin having an epoxy molar mass ~grams resin/
grams equivalent of epoxy) of at least 10,000, at least 5% of epoxy gr~ups
of the mcdified epoxy resin modified with a monofunctional carboxylic acid
and/or a monofunctional phenol by reaction with the respective carboxyl or
hydroxyl groups thereof, and, optionally, no m~re than 95% of epoxy groups
of the modified epoxy resin modified by intermolecular reaction and/or by
cross-linking with a ~olyfunctional epoxy hardener.
In another aspect, the present invention comprises a process of
preparing the above defined toner powder, the process comprising the steps
of homogeneously mLxing the thermoplastic resin in a molten s-tate with the
polarity control agent and colouring materials
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cooling the mass ~lus obtained, 3nd grinding said cooled n~ss to the desired
degree of finen-ss, wherein epoxy groups of an epoxy resin oE lc~er epoxy
molar mass chosen as starting ma-terial are n~dified with the monofunctional
carboxylic acid and/or phenol durlng said mixing of the ingredients, and
optionally wherein modification during said mixing of the ingredients is
also achieved by inter-molec~ular reaction and/or cross-linking with the poly-
functional hardener.
sy epoxy resins are meant in the context of this invention conden-
sation products of a polyphenol, in particular a bisphenol, with a halohydrin
in particular epichlorohydrin.
The modiEied epoxy resin to be used in the toner pc~er a~cording
to the invention can be obtained, for example, by modifying in the way indi-
cated above one of the commercially available epoxy resins, or a mixture of
such resins, which, as .t is well knc~n, have an epoxy mol~r mass (herein-
after referred to as E.M.M.) being considerably below the minimum of 10,000
required in the present case. By epoxy n~lar mass is meant the mass of
resin in grams which contains one gram equivalent of epoxy :(see pages 4 14
Of "Hanc~ook of Epoxy Resins" by Lee and Neville, McGraw Hill sook Company,
- 1967). Epoxy molar mass was for~erly referred to in the art as epoxy
eqlivalent mass. The choice of the resin or resins to be used as starting
product for this purpose is mainly determined by the requirement that the
toner powder must be stable at temperatures up to 50C, and that it must
have a melting poin-t between 55 and 150C. m e first requirement is
connected with the aspect that, till the fusing step, temperatures up to
50C may occur in every stage, such as storing, staying and processing,
in the copying apparatus. me second requirement is especially connected
with the maximumallc~able temperature of the copying paper cluring fusing,
because utherwise discolouration or even burning may occur. In copying
apparatus in which a less inflammable substratum than paper, for exar~le,
glass or metal is employed, resins having a higher mel-ting point can, of
coarse, also be used for the toner powder.
EYamples of epoxy resins that are quite useful as starting product
for the preparation of the modified epoxy resin to be applied in -the toner
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powder according to the invention are Epikote 100~* ~melting point 90 - 100C,
E.M.M. 850 - 940, both data according to supplier~s specifications),
Epikote 1006* ~115 - 125C, E.M.M. 1~550 - 1,900), Epikote 1007* ~120 - 130C,
E.M.M. 1,700 - 2,050), and Epikote 100~* ~1~0 - 155C, E.M.M. 2,300 - 3,~00).
Howe~er, as will be explained hereafter in the specification, under certain
circumstances it is also possible to use epoxy resins having lower or higher
melting points than those mentioned above as starting product.
The toner powder according to the invention may contain epoxy
resin of which between 5 and 100% of the epoxy groups are modified with a
monofunctional carboxylic acid andjor phenol. The required E.M.M. of 10,000
or higher can be obtained by modifying approximately 80 to 100% of the epoxy
groups of the epoxy resin chosen as starting product with a monofunctional
carboxylic acid and/or phenol. However, it can also be achieved by modifying
at least approximately 80% of the epoxy groups of the epoxy resin partly
with a monofunctional carboxylic acid and/or phenol, and partly by inter-
molecular reaction. Of course, it must then be ensured during the modifica-
tion process that the conditions required for performing both kinds of
modifications are available. In general, these are satisfied if the tempera-
ture and duration of the modification process are properly selected. The
intermolecular reaction between the epoxy groups of the epoxy resin generally
proceeds satisfactorily at temperatures of between 150 and 250C and resi-
dence time of 120 secs. to 5 minutes. At the said tempe~atures modification by
means of the monofunctional carboxylic acid and/or phenol proceed considera-
bly faster than the intermolecular reaction.
The desired minimum E.M.M. can be obtained as well by combining
the modification by means of a monofunctional carboxylic acid and/or phenol
with a modification performed by cross-linking, using one of the polyfunctional
epoxy hardeners known per se. Examples of hardeners suitable for the purpose
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are succinic anhydride, maleic anhydride, succinic acid and bisphenol A. As
such cross-linking reactions generally proceed very quickly at 110 to 150C~
said combination leads to the desired result, already within several minutes,
when the modification takes place at temperatures between round 100 and 150Co
In all cases, however, at least 5% of the epoxy groups of the
epoxy resin chosen as starting product for the preparation of the toner pow-
der according to the invention must be modified with a monofunctional car-
boxylic acid and/or phenol, because otherwise the toner powder does not meet
the requirements made hereinbefore in respect of melting point and repro-
ducibility of the fusing behaviour.
Which percentage of the epoxy groups is modified with a mono-
functional carboxylic acid and/or phenol, and which by intermolecular reaction
and epoxy hardening, respectively, depends on the purpose the toner powder
according to the invention has to serve.
If the toner powder is intended for the preparation of a developer
for use in apparatus equipped with a radiation fusing device, it is advisable
to modify a percentage as high as possible but, in general, at least 50%,
and preferably at least 75% of the epoxy groups of the resin chosen as start-
ing product, with a carboxylic acid and/or phenol. The fact is that for
use in a radiation fusing device the toner powder should have a fusing range
as small as possible with an initial melting point as low as possible. By
modifying as high as possible a percentage of the epoxy groups with a mono-
functional carboxylic acid and/or phenol, and a percentage as low as possible
by intermolecular reaction or by epoxy hardening, the fusing range, mostly
being rather small itself, and the initial melting point of the epoxy resin
chosen as starting product for performing the modification, are only changed
*o a practically negligible extentO
An additional advantage of a modification almost exclusively with
a monofunctional carboxylic acid and/or phenol is that ~he modification can
be performed very quickly and at relatively low temperatures in a highly
reproducible way.
If the toner powder is intended $or the preparation of a developer
to be used in contact-fusing devices, which are preferred to radiation
fusing devices especially in copying apparatus which are to attain high
printing speeds, the best results will be obtained according to whether the
modification of the epoxy groups of the resin, chosen as starting product,
with a monofunctional carboxylic acid and/or phenol is closer in the neigh-
bourhood of the required minimum rate of 5%~ whereas the remaining modifica-
tion percentage, required for attaining the minimum epoxy molar mass of ~-
10,000, is obtained by intermolecular reaction between the epoxy groups
of the epoxy resin or by epoxy hardening. The resin so obtained and, thus,
the toner powder prepared therefrom has a large fusing range, which is a de-
sired property for toner powders for developers intended for use in apparatus
equipped with a contact-fusing device. In general, the fusing range of the
modified epoxy resin increases as the percentage of modification with a mono-
functional carboxylic acid and/or phenol is nearer to the minimum rate of 5%.
However, the melting point of the modified resin then shifts to a higher level,
so that it may be desired, in certain cases, to modify more than 5% of the
epoxy groups with a monofunctional carboxylic acid and/or phenol, because
otherwise the melting point of the resin obtained will be too high for proper
and economical fusing. However, within certain limits this drawback may be
met by starting from an epoxy resin having a relatively low melting point,
such as Epikote* 10049 1002 or 1001.
But for the carboxyl and hydroxyl group, respectively) the mono-
functional carboxylic acids and/or phenols to be used for the modification of
the epoxy resin chosen as starting product may not contain any further sub-
stituent that might react with the epoxy groups of the epoxy resin under the
` conditions prevailing during the modification process.
Particularly suitable are aliphatic and aromatic carboxylic acids
and phenols, as well as those which are substituted by one or more alkyl,
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aralkyl, cycloalkyl, aryl, alkylaryl, alkoxy or aryloxy groups, and which are
not volatile, or substantially not, under the conditions prevailing during
the modification process.
Examples of such carboxylic acids are benzoic acid, 2, 4-dimethyl-
benzoic acid, 4-~a,a-dimethylbenzyl)-benzoic acid, 4-phenylbenzoic acid and
4-ethoxybenzoic acid. Further, the satured aliphatic carboxylic acids;
heptanoic acid, nonanoic acid, dodecanoic and isododecanoic acid, hexadecanoic
acid and octadecanoic acid.
Examples of the above phenolic compounds are 4-n-butyl phenol, 4-n-
pentyl phenol, 2, 3, 4, 6-tetramethyl phenol, 2, 3, 5, 6-tetramethyl phenol,
4-~a,a-dimethyl) benzyl phenol, 4-cyclohexyl phenol, 3-methoxy phenol, 4-
methoxy phenol and 4~ethoxy phenol.
Of the compounds mentioned above octadecanoic acid, subs~ituted or
non-substituted benzoic acid and 4-~a,a-dimethyl) benzyl phenol are most
preferably used.
The modification of the epoxy resin chosen as starting product to ~;
become the modified epoxy resin for use in the toner powder according to the
invention preferably occurs during preparation of the toner powder itself.
Surprisingly it has appeared that in this way the modification process can
be performed well and be controlled satisfactorily, so that in thls way a
tailor-made toner powder of excellent quality can be obtained. Moreover, in
that case no special catalyst or other additive is required for performing
the modification with the monofunctional carboxylic acid and/or phenol
satisfactorily, which is an additional advantage.
Admittedly, it might also be possible to carry out the modification
of the epoxy resin, chosen as the starting product, in a separate process.
However, a number of difficulties are attached to that process and, conse-
quently, it is less advisable. ~or example, a special operation and, in most
cases, a catalyst for a correct controlling of the modification with the mono-
functional carboxylic acid and/or phenol are required. In most cases, this
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catalyst must entircly be rcmove~ again together with the solvcnts tllat may
have been used. This is no~ ollly onerous uu~ of~e~ uoes no; juccced in ~'
a sufficient de~ree, as a result of which the toner powder preparccl with the
resin thus modified will generally deteriorate quickly.
The toner powder according to thc invention can be prepared by
means of one of the methods generally kno~ for the preparations of toner
powders such as, for example, the kneadingJ extrusion or hot melt method.
According to the two fi.rst methods the resin, the polarity control agent, the
colouring materials andJ if desired, other inaredients are generally mixed
together at approximately 90 - 130C, according to the last-mentioned method
this mixing generally occurs at roulld 200C. After cooling, the resulting
mass is ground to particles of the deslred degree of fineness, in general
between 2 and50~m.
Of the three manufacturing methods mentioned above the hot melt
method has proved to be the most suitable one for the preparation of the
.
toner powder according to the invention. The toner powder prepared according
to that method even proves to be more satisfactory and to be reproducible to.
a higher degree, in particular with regard to its most essential properties
such as charge behaviour, sta~ility and fusing behaviour, than wllen the two
other methods are applied. Moreover, most polarity control agents and dyes
dissolve sufficiently in the resin at temperatures round 200C, so that the
homogeneous composition of the toner powder required foT the charge properties
can be attained without the necessity of ma~ing special arrangements.
; However, toner powder according to the invention of satisfactory
quality can also be obtained with the kneading and extrusion method, provided
certain provisions are observed. The fact is that at temperatures at which
these two mcthods generally are performed, namely, at approximately Y0 to
130C, the most conventional polarity control agents and dyes do not dissolve
sufficiently in the resin to cffect the desired homogelleous mi~ture. This
holds good in particular with regard to the preferred polarity control agents
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of the nigrosine type.
In such cases, successful use can be made of a sub-
stance capable of promoting,the dissolution of the polarity con-
trol agent, such as described in Applicant's-not pre~o~-~y ~ub-
~e~e~ Dutch Application No. 7415325.
In general, the amounts to be used range between a few
; per cent and some tens of per cents.
Advisable, in particular, is the use of the diphenyl-
phthalate or N-cyclohexyl-p-toluenesulphonamide referred to in
said patent application.
Moreover, since the modification by intermolecular re-
action of the epoxy groups of the epoxy resin chosen as a start-
ing product proceeds relatively slowly at said temperatures, it
is advisable, if the required modification of the epoxy groups is
desirably to be effected only partly with the monofunctional
- carboxylic acid and/or phenol, to combine the modification with
cross-linking by means of a polyvalent epoxy hardener.
Although the use of the compounds, described in said
Dutch Patent Application as dissolving accelerators, is in fact
superfluous if the toner powder according to the invention is
prepared by the hot melt method, for a number of reasons their
use may nevertheless be also advantageous in that case. For ex-
ample, their addition to the reaction mixture causes a decreased
melting point of the toner powder ultimately obtained, and by
that the possibility of also using, as starting product for the
preparation of the toner powder according to the invention, epoxy
resins of which the melting point is higher than 150C. It is
also possible to use this addition in order to restore the melting
; point of the toner powder to its desired level9 if this should
have become too high as a result of the major part of the epoxy
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groups of the epoxy resin being modified by intermolecular re-
action or cross-linking with a polyvalent epoxy hardener.
In addition to the modified epoxy resin or the mixture
of modified epoxy resins the finely divided, coloured toner part-
icles of the toner powder according to the present invention may
contain other ingredients. The modified epoxy resin can be
mixed, in particular, with a phenoxy resin such as, for example, ;~
Rutopox* 07-17, a product from Messrs. Bakelite. However, the ~
ratio modified epoxy resin: phenoxy resin should amount to at ~ m
least 1:1, preferably to at least 1.5-1.75:1.
The addition of phenoxy resins, a generic term for
amorphous poly (hydroxy-ethers) that have been derived from di- ;
phenols and epichlorohydrin and have a high molecular weight, ex-
tends the fusing range of the toner particles. This affords the
possibility, for example, of making a toner powder based on an
epoxy resin, being exclusively or predominantly modified with a
monofunctional carboxylic acid and/or phenol, also suitable for
use in an apparatus equipped with a contact-fusing device.
To prepare a powder developer of the two-component
type, the toner powder according to the invention is mixed,
either immediately after its preparation or in a later stage,
with the desired carrier particles. If the developer is intended
for magnetic brush development magnetic iron particles, which may
be provided with a surface layer, are used as carrier. The de-
sired particle size of the carrier are known to those skilled in
the art. In general, its dimensions range between 50 and 150 ~m.
Dependent on the particle size of the two components the two- ;
component developer generally contains from 1 to 8% by weight of
toner particles. ;
The developers thus ob-tained can be used satisfactorily
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for the development of latent electrostatic images having a neg-
ative charge, such as they are obtained, for example, on electro-
photographic elements based on zinc oxide.
The invention is further illustrated with reference
to the following Examples.
EXAMPLE 1
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In a vessel, provided with a stirrer and an oil bath
heating 468 g of the epoxy resin Epikote* 1006 (E.M.M.=1700, sup-
plied by Shell) were gradually added at 200 C to a mixture of 36
g of nigrosine base (Colour Index third ed. No. 50415:1), 60 g of
~-cyclohexyl-p-toluenesulphonamide and 30 g of benzoic acid.
After mixing, the ingredients were fully dissolved in one an-
other. Subsequently, 36 g of carbon were added and the whole was
stirred for two hours at 200C, a proper dispersion of the carbon
thus being achieved. The hot melt was then cooled down and
ground and sieved in a way known by itself to a toner powder hav- -
ing particles between 8 and 27 ~m. The E.M.M. oE the resin mod-
ified with benzoic acid in the toner powder, which was determined
in the way analogous to the method of analysis 2.3.2.7.2. prac-
tised by the Synthetic Materials Institute T.NØ, Delft, exceeded ~ ;
40,000. The content of unreacted benzoic acid in the toner pow-
der was smaller than 0.1%. Consequently, the resin had been mod- ~
ified for 90% with benzoic acid. The toner powder had a glass -
transition temperature (Tg) of 56C. The Tg was determined from
the D.S.C. thermogram recorded by a Du Pont 990 thermal analyzer.
Also after prolonged heating at 200C, a temperature which is well
over the temperatures usually applied in fusing devices, the Tg
remained constant at 56C, which shows that the toner thermally
was stable.
Four parts by weight of the toner powder thus prepared
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were properly mixed with 96 parts by weight of iron powder hav-
ing particles between approximately 55 and 130 ~m. The toner
powder in the developer so obtained had a pronounced positive
polarity. The triboelectric charge amounted to ~13~C per gram
toner powder. By means of this developer combined with a photo~
conductor based on zinc oxide as described in the Dutch Patent
Application 7217484, first-class copies on plain paper were ob-
tained in an automatically operating copying apparatus, permit-
ting wide tolerances in adjusting its functions and the concen-
tration of the toner. The toner powder also processed a verygood permanence during prolonged use in the copying apparatus.
In an endurance test, whereby the concentration of the toner in
the developer was kept constant by adding extra toner powder, in
order to compensate for the toner powder used in the copying
process, copies of good quality were still obtained after a run
of 40,000 prints. In a radiation fusing device
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as described in the Dutch Patent Application 7205491 the toner powder can be
fixed rapidly and well onto paper at a set temperature of approximately 150C.
The toner powder could also be fixed in a contact-fusing device. The contact-
fusing device used was fitted with a roller coated with silicone rubber, of
which the top layer had been previously aged in a prolonged copying process.
Fusing ranges which were shorter but which corresponded more to practice than
with the use of new silicone rubber were found. The effective contact time
of the copy with the heated roller amounted to 1.3 seconds. The toner pow-
der possessed a reasonable fusing range, namely, from 87 to 109C ~range
length 22C). In that case the lower limit was the temperature at which the
fusion of the toner powder was just sufficient, and the upper limit was the
temperature at which the transfer of the molten toner powder to the silicone
rubber set in.
EXAMPLE 2
The preparation according to Example 1 was repea*ed in batches of
630 g, 6.3 kg and 126 kg, respectively. The measuring and copying results of
the toner powders thus obtained were practically identical to those described
in Example 1, from which it may be concluded that the reproducibility of the
preparation is good.
EXAMPLE 3
In a powder mixer a ground mixture of nigrosine base, N-cyclohexyl-
p-toluenesulphonamide and benzoic acid was premixed at room temperature with
Epikote*1006 and carbon in the ratios mentioned in Example 1. This mixture
was then extruded in one operation in a laboratory double-screw extruder,
model Davo M.S. 2.1, at a temperature of 150C in the kneading zones. The
residence time was approximately 5 minutes. The cooled melt was processed
to toner powder and examined in the way described in Example 1, resulting
in practically equal results. These results, obtained after a preparation
whereby the residence time and *emperature conditions were clearly different
from those according to Example 1, illustrate a wide margin applicable in
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the useful preparing conditions.
EXAMPLE 4
According to the process described in Example 1, a hotmelt was prepared from 36 g of nigrosine base, 60 g of N-cyclo-
hexyl-p-toluenesulphonamide, 416.8 g of Epikote* 1006, 36 g of
carbon, but now with 51.2 g of the modification compound 4-(~
dimethylbenzyl) phenol (=p-cumylphenol, supplied by Fluka). After
cooling down, grindîng and sieving, a toner powder having a part-
icle size between 7 and 28 ~m was obtained. The E.M.M. of the
modified epoxy resin was higher than 40,000. The modification
rate was 100%. The Tg of the toner powder was 50C and remained
constant after prolonged heating at 200 C.
In a developer prepared as in Example 1, the toner
powder could be provided with a pronounced positive charge of 13
~C/g. The toner powder did hardly dust during use, which points
to a highly uniform charge distribution. An excellent image
quality was obtained. The toner powder was eminently permanent ;
and could be fixed in a radiation fusing device at a set temper-
ature of 145C. The contact fusing range was 81 to 107C (length
26C).
Using the above formula a toner powder was also pre-
pared in an A.M.K. kneading mixer at an equilibrium temperature
of appraximately 110C and a total residence time of 2 hours.
The E.M.M. of the modified resin thus obtained was 15,000. The
Tg was 54 C and was still nearly unchanged after heating for some
time at 200 C. The copying and fusing results were practically
equal to those of the toner powder prepared according to the hot
melt method.
EXAMPLE 5 `~
According to the process of Example 1, a hot melt was
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prepared from 36 g of nigrosine base, 30 g oE N-cyclohexyl-p-
toluenesulphonamide, 406.6 g o~ Epikote* 1006, 36 g of car~on,
but now with 61.4 g of the modification compound octadecanoic
acid (equivalent mass = 285). After cooling, grinding and siev-
ing a toner powder having a particle size between 8 and 32 ~Im was
obtained. The Tg was 43 C and remained constant, also after
heating for some time up to 200C. The E.M.M. of the modified
resin was 40,000. The modification rate was 90%. In a developer
prepared as in Example 1, the toner. powder could be provided with
a pronounced positive charge of 14 ~C/g. It dusted very slightly.
A very good image quality was obtained. The toner powder was
properly permanent, could be fixed in a radiation fusing device
at 135C, and had a contact-fusing range of 75-98C (length 23 C).
EXAMPLE 6
In a reaction vessel as described in Example 1, 528 g
of Epikote* 1004 (E.M.M. = 900), 36 g of nigrosine base and 66 g
of benzoic acid were mixed for one hour at 200C. The ingredients
thereby fully dissolved in one another. Subsequently, 36 g of
carbon were added and stirring was continued for another hour at
200C. The cooled melt was ground and sieved to a toner powder ;
having particles between 8 and 24 ~m. The E.M.M. was 40,000.
Before and after heating at 200C the toner powder had a constant
Tg value of 63 C. The charge of the toner powder in a 4 per cent
developer was 11 ~C/g. A good image quality was obtained. The
toner powder could be fixed onto paper at a temperature of 155C
in the radiant fusing device. The contact-fusing range was 87-
103C (length 16C).
EXAMPLE 7
Example 1 was reworked, but now wlth 36 g oE nigrosine
hydrochloride (Colour Index third ed. No. 50415) instead of the
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nigrosine base. The E.M.M. and constant Tg value of the toner
powder were 40,000 and 66C, respectively. Satisfactory copying
and fusing results were obtained.
EXAMPLE 8
Example l was reworked, but now with 31.9 g of 2-
hydroxybenzoic acid instead of the benzoic acid, and with 436.1 g
of Epikote* 1006. The modification rate was 90%. The E.M.M. and
constant Tg value were 40,000 and 57C, respectively. Satisfact-
ory copying and fusing results were obtained.
EXAMPLE 9
Example 1 was reworked, but now with 41.1 g of 3,4-
dimethoxybenzoic acid instead of the benzoic acid, and with 426.9
g of Epikote* 1006. The modification rate was 90%. The E.M.M.
and constant Tg value were 40,000 and 57 C, respectively. Good
copying and fusing results were obtained.
EXAMPLE 10 (Comparative Example)
The preparation according to Example 1 was repeated,
but now with the omission of the modification compound benzoic
acid. The cooled melt could be ground only with difficulty and
the toner powder obtained could not be fixed in the radiation
fusing device under the scorch limit of the paper.
EXAMPLE 11
.. ~
According to the preparing method of Exa~ple l, a hot
melt was prepared from 30 g of nigrosine base, 75 g of N-cyclo-
hexyl-p-toluenesulphonamide 12.5 g of (4-~ dimethylbenzyl`-
phenol, 352.5 g of Epikote* 1006 and 30 g of carbon. The E.M.M.
was 21,000. The rest of the unreacted modification compound was
<0.1%. The Tg was 54 C and did not change after heating for 30
minutes at 200 C.
The modification rate effected by the phenol amounted
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to 30%. In a developer prepared in the manner described in
Example 1 the toner powder prepared from the cooled melt and hav-
ing a particle size between 7 and 31 ~m acquired a pronounced
positive charge of 13 ~C/g. The toner powder yielded excellent
copies in a copying apparatus, permitting wide tolerances in ad-
justing its functions and the concentration oE the toner. In a
radiation fusing device the toner powder could be fixed at a
temperature of 155C. In the contact-fusing device described be-
fore the fusing range was 88-121 C (length 33 C).
EXAMPLE 12
Analogous to the process of Example 1 a hot melt was -
prepared from 36 g o~ nigrosine, 60 g of N-cyclohexyl-p-toluene-
sulphonamide, 51.6 g of benzoic acid and 372 g of Epikote* 1004.
After mixing for one hour, the E.M.M. of the resin increased from ;
900 to 40,000 (90æ modification). Subsequently, 36 g of carbon
and 96 g of Rutapox* 07-17 were added, and the stirring operation
was continued for one hour at 220 C (Rutapox* 07-17 is a bis-
phenol A-epichlorohydrin phenoxy resin with an average molecular
weight of 25-30,000, supplied by Bakelite). The Tg of the mix-
ture was 47C and remained constant after heating at 200C. The
toner powder prepared from this mixture had a particle size dis-
tribution between 9 and 28 ~m. The obtainable charge was 12
~C/g. Excellent copies were obtained. The toner powder could be ~ -
; fixed in a radiant fusing device at 145C, and had a wide contact-
fusing range, namely, 79-114C (length 35 C).
- A comparable toner powder which contained no Rutapox*
07-17 but only modified Epikote* 1004 as a resin, had a contact-
fusing range of 80-96 C (length 16 C).
EXAMPLE 13
In a powder mixer a ground mixture of 36 g of nigrosine `
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base, 60 g of N-cyclohexyl-p-toluenesulphonamide, 9.7 g of ben-
zoic acid and 9.3 g of succinic acid was premixed with 36 g of
carbon and 449 g of Epikote* 1006. This mixture was then ex-
truded at 160C. The residence time in the extruder was approx-
imately 5 minutes. The mixture had a constant Tg value of 61C.
The E.M.M. was higher than 40,000. The modification rate with
benzoic acid was 30%. The toner after being mixed with iron to a
4 per cent developer gave a good image quality, and had a wide
contact-fusing range of 89-129C (length 40C).
EXAMPLE 14
In the manner of Example 1, 36 g of nigrosine base,
60 g of N-cyclohexyl-p-toluenesulphonamide, 468 g of Epikote*
1006 and 36 g of carbon were mixed for two hours at 200 C. Sub-
sequently, a mixture of 6 g of nigrosine base, 10 g of N-cyclo-
hexyl-p-toluenesulphonamide, 5.0 g of benzoic acid, 79 g of
Epikote* 1006 and 6 g of carbon was added and stirred for another
30 minutes at 200 C. After cooling, grinding and sieving, a
toner powder was obtained which, upon examination in the manner
described in Example 1, gave a good copy quality with wide toler-
ances in the toner/iron ratio and in setting the apparatus. The
constant Tg value was 68 C; the E.M.M. was 40,000. The rate of
epoxy resin modified with benzoic acid in the toner was 15%. The
toner could be fixed well at a set temperature of 170 C in the
radiant fusing device.
In the arrangement described before, the contact-
fusing range was 99-148C (length 49 C).
EXAMPEE 15
Substantially in the same way as described in Example
1, a hot melt was prepared by heating, whilst continuously stir-
ring, during one hour and at 200C a mixture of 341.6 g Epikote*
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1001 (m.p. 60-70 C; Durrance; E.M.M. 450-500) 124.4 g (4-a,a-
dimethylbenzyl)-phenol, 48.0 g nigrosine Base G.B., 48.0 g
Printex G*.
The E.M.M. of the Epikote* 1001 appeared to have
increased to 16,300. Subsequently, 240 g Rutapox* 07-17 were
gradually added whilst maintaining the temperature at 200 C and
continuously stirring. After approximately another hour the
; mixture was found to be completely homogeneous.
Then the mixture was cooled down, g~ound and sieved
to a toner powder having particles between 8 and 25 ~m. The
contact fusing range of this toner powder was ~rom 83 to 140C,
which made it particularly useful for application in a developer
for use in a copier equipped with a contact fusing device.
t~
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