FIELD OF THE INVENTION AND RELATED ART
[0001] The present invention relates to a toner, particularly a negatively chargeable toner,
for developing electrostatic images in image forming methods, such as electrophotography,
and electrostatic printing. The present invention also relates to an image forming
method and a-process cartridge using the toner.
[0002] Hitherto, a large number of electrophotographic processes have been known, as disclosed
in U.S. Patent Nos. 2,297,691; 3,666,363; 4,071,361 and others. In these processes,
an electric latent image is formed on a photosensitive member comprising a photoconductive
material by various means, then the latent image is developed and visualized with
a toner, and the resultant toner image is, after transferred onto a transfer-receiving
material, such as paper, as desired, fixed by heating, pressing, heating and pressing,
etc., to obtain a copy or a print. In the case of including the step of transferring
a toner image, a step of removing a residual toner remaining on the photosensitive
member is ordinarily also included.
[0003] Known developing methods for visualizing electrical latent images with a toner may
include, e.g., the magnetic brush method described in U.S. Patent No. 2,874,063, the
cascade developing method disclosed in U.S. Patent No. 2,618,552, the powder cloud
method disclosed U.S. Patent No. 2,221,776, and a method using an electroconductive
magnetic toner disclosed in U.S. Patent No. 3,909,258.
[0004] As for the step of fixing the toner image onto a sheet material such as paper which
is the final step in the above process, various methods and apparatus have been developed,
of which the most popular one is a heating and pressing fixation system using hot
rollers.
[0005] In the heating and pressing system, a sheet carrying a toner image to be fixed (hereinafter
called "fixation sheet") is passed through hot rollers, while a surface of a hot roller
having a releasability with the toner is caused to contact the toner image surface
of the fixation sheet under pressure, to fix the toner image. In this method, as the
hot roller surface and the toner image on the fixation sheet contact each other under
a pressure, a very good heat efficiency is attained for melt-fixing the toner image
onto the fixation sheet to afford quick fixation.
[0006] Recently, in place of hot rollers, there has been commercialized a fixing apparatus
comprising a heating member and a pressing member which is disposed opposite to the
heating member and presses a recording medium (such as paper) to contact the heating
member via a film.
[0007] On the other hand, in recent years, there have been also desired high-quality copy
or print images in accordance with the use of digitalized copying machines and fine
toner particles.
[0008] More specifically, it has been desired to obtain a photographic image accompanied
with characters, so that the character images are clear while the photographic image
is excellent in density gradation faithful to the original. Generally, in a copy of
a photographic image accompanied with characters, if the line density is increased
so as to provide clear character images, not only the density gradation characteristic
of the photograph image is impaired, but also the halftone part thereof are roughened.
[0009] Further, resolution failure (collapsion) of line images and scattering are liable
to be caused at the time of fixation as described above, so that the image qualities
of the resultant copy images are rather liable to be deteriorated.
[0010] Further, in case where the line image density is increased, because of an increased
toner coverage, a thick toner image is pushed against a photosensitive member to be
attached to the photosensitive member in the toner transfer step, so that a so-called
transfer failure (or a hollow image), i.e., a partial lack toner image (line images
in this case), in the transferred image, is liable to be caused, thereby providing
poor quality of copy images. On the other hand, in case where the gradation characteristic
of a photographic image is intended to be improved, the density of characters or line
images is liable to be lowered, thus providing unclear images.
[0011] In recent years, there has been obtained some improvement in density gradation characteristic
by a system including image density readout and digital conversion. However, a further
improvement has been desired.
[0012] Regarding density gradation characteristic, it is impossible to obtain a linear relationship
between a developing potential (difference between a photosensitive member potential
and a developer-carrying member potential) and a resultant (copy) image density. In
a halftone region, a slight change in developing potential leads to a remarkable change
in image density. This provides a complexity in obtaining a satisfactory density gradation
characteristic.
[0013] Generally, copied images appear clearer because of an edge effect of attracting an
increased amount of toner so that clear line images can be retained in case where
a maximum density of ca. 1.30 is attained at a solid image part which is less affected
by the edge effect.
[0014] In case of a photographic image, however, the maximum density of a photograph appears
less at a glance because of its surface gloss but actually amounts to a very high
level of 1.90 - 2.00. Accordingly, in a copy of a photographic image, even if the
surface gloss is suppressed, a solid part image density of ca. 1.4 - 1.5 is required
since a density increase due to the edge effect cannot be expected because of a large
image area.
[0015] Accordingly, in providing a copy of a photographic image accompanied with characters,
it becomes very important to obtain a developing potential-image density relationship
which is close to the first order (linear) one and also a maximum image density of
1.4 - 1.5.
[0016] Further, the density gradation characteristic is liable to be remarkably affected
by the saturation charge and the charging speed of a developer used. In case where
the saturation charge is appropriate for the developing conditions, a developer showing
a slow charging speed provides a low maximum image density, thus generally thin and
blurred images in the initial stage of copying. In this case, however, non-problematic
images can be obtained if the maximum image density is ca. 1.3, as described above,
thus being able to obviate an adverse effect of the slow chargeability. Even in case
of the slow charging speed, the initial copy image density is increased if the saturation
charge is increased. However, on continuation of copying, the charge of the developer
is gradually increased to finally exceed an appropriate charge for development, thereby
resulting in a lower copy image density. Also in this case, no problem occurs in line
images if the maximum image density is ca. 1.3
[0017] From the above, it is understood that a photographic image is more remarkably affected
by the saturation charge and the charging speed of a developer than a line image.
[0018] In case where a smaller particle size toner is used, the dispersion state of a charge
control agent and a colorant remarkably affects the chargeability of the toner.
[0019] A toner for developing electrostatic images may generally contain a dye called a
charge control agent for controlling the chargeability of the toner. In order to provide
a toner with a negative chargeability, chromium complex compounds have been principally
used.
[0020] Japanese Laid-Open Patent Application (JP-A) 60-170864, describes that, among such
chromiun complex compounds, those having a good mutual solubility with a binder resin
show a uniform negative chargeability and provide clear copy images but are liable
to be accompanies with difficulties, such remaining of a toner residue on a photosensitive
member due to cleaning failure and filming, and those being insoluble within a binder
resin (particularly in a polyester resin) show good chargeability and also good anti-filming
characteristic.
[0021] However, a metal complex salt compound insoluble or incompatible with a binder resin
shows a poor dispersibility. Accordingly, when a toner containing such a metal complex
salt compound is formulated into fine particles, the toner is liable to be charged
excessively particularly in a low-humidity environment, thus leading to fog or a density
lowering. This is because a fine particle size fraction and a coarse particle size
fraction formed through a pulverization step of toner production are caused to have
remarkably different contents (weight ratios) of the charge control agent (i.e.,so-called
localization of a charge control agent), so that toner particles are caused to have
different chargeabilities.
[0022] In case where a fine powder fraction and a coarse powder fraction recovered from
the classifying step are re-utilized as a material for toner production, the above-mentioned
liability of localization of a charge control agent is further promoted to cause difficulties,
such as a lowering in image density and fog due to a toner electrification insufficiency
under a low-humidity condition. For this reason, it has been hitherto difficult to
reutilize both fine powder and coarse powder by-produced in the classification step
for toner production, and coarse powder alone has been reutilized as proposed in JP-A
3-209266. JP-A 61-155464 and JP-A 62-177561 have proposed an azo-type iron complex
as a charge control agent showing good dispersibility within a binder resin. A toner
containing the azo-type iron complex is, however, accompanied with difficulties, such
as a slow rate of electrification and a lowering in image density after a long period
of standing or in a high humidity environment. In recent years, a smaller particle
size (at most 9 µm in terms of a weight-average particle size (diameter)) is recommended
for providing high-quality images. A small particle size toner is liable to have a
remarkably high charge under a low-humidity condition and cause difficulties, such
as thinning of line images, a lowering in image density and occurrence of reversal
potential fog caused by a toner charged to an opposite polarity due to charging failure
on a developer-carrying member, such as a developing sleeve, due to the copresence
of the excessively charged toner.
[0023] In order to improve the chargeability of a toner containing such an azo-type iron
complex, JP-A 1-306862 has proposed a silicone resin-coated carrier which has a high
chargeability-imparting effect, and JP-A 2-153362 has proposed a developing apparatus
including an improved toner layer thickness-regulating member and an improved toner
replenishment-assisting member. In these proposals, the developing performance of
the toner is retained by charge-imparting or -assisting members and it is difficult
to retain good image quality for a long period due to deterioration or soiling of
the charge-imparting or -assisting member.
SUMMARY OF THE INVENTION
[0024] An object of the present invention is to provide a toner for developing electrostatic
images having solved the above-mentioned problems and capable of retaining a high-quality
image forming performance for a long period.
[0025] An object of the present invention is to provide a toner having a good dispersibility
of a charge control agent and a uniform chargeability, capable of retaining a high
image density for a long period and capable of providing images free from fog and
with a high resolution.
[0026] Another object of the present invention is to provide a toner which can be quickly
charged and can provide good toner images similarly as before standing even after
standing for a long period or in a high-humidity environment.
[0027] Another object of the present invention is to provide a toner which can provide high-quality
images without using a charge-assisting member.
[0028] Another object of the present invention is to provide a fine particle size toner
which can provide satisfactory developed images for a long period under various environmental
conditions even in case of providing high-resolution developed images.
[0029] Another object of the present invention is to provide a toner which allows re-utilization
of fine powder and coarse powder by-produced in the classification step in toner production.
[0030] Another object of the present invention is to provide a toner highly suitably adapted
to an electrophotographic process not adversely affecting a photosensitive member
or a developer-carrying member.
[0031] A further object of the present invention is to provide an image forming method and
a process cartridge using such a toner as described above.
[0032] According to the present invention, there is provided a toner for developing electrostatic
images, comprising:
(a) a binder resin,
(b) a long-chain alkyl compound represented by the following formula (1), (2) or (3):
wherein x denotes an average value in the range of 35 - 150,
wherein x denotes an average value in the range of 35 - 150; z denotes an average
value in the range of 1 - 5, and R denotes H or an alkyl group having 1 - 10 carbon
atoms,
wherein y denotes an average value in the range of 35 - 150; and
(c) an azo-type iron complex compound represented by the following formula (4);
wherein X
1 and X
2 independently denote hydrogen atom, lower alkyl group, lower alkoxy group, nitro
group or halogen atom; m and m' denote an integer of 1 - 3; R
1 and R
3 independently denote hydrogen atom, C
1-18 alkyl or alkenyl, sufonamide, mesyl, sulfonic acid group, carboxy ester group, hydroxy,
C
1-18 alkoxy, acetylamino, benzoylamino or halogen atom; n and n' denote an integer of
1 - 3; R
2 and R
4 denote hydrogen atom or nitro group; and A
+ denotes a cation including 75 - 98 mol. % of ammonium ion and another ion selected
from the group consisting of hydrogen ion, sodium ion, potassium iron and mixtures
thereof.
[0033] According to another aspect of the present invention, there is provided an image
forming method, comprising:
a charging step of supplying a voltage to a charging means in contact with a member
to be charged to charge the member to be charged,
a step of forming an electrostatic image on the charged member to be charged,
a developing step of developing the electrostatic image with a toner as described
above to form a toner image on the member to be charged,
a transfer step of transferring the toner image to a transfer-receiving material directly
or via an intermediate transfer member, and
a fixing step of fixing the toner image onto the transfer-receiving material.
[0034] According to a further aspect of the present invention, there is provided a process-cartridge,
comprising at least a developing means and a photosensitive member,
the developing means and the photosensitive member being integrated into a cartridge
which is detachably mountable to a main body of an image forming apparatus,
wherein the developing means contains a toner as described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] Figure 1 is a schematic illustration of an image forming apparatus used in Examples
of the present invention.
[0036] Figure 2 is an exploded perspective view of essential parts of a fixing apparatus
used in Examples of the invention.
[0037] Figure 3 is an enlarged sectional view of a fixing apparatus including a film in
a non-driven state used in Examples of the present invention.
[0038] Figure 4 is a partial illustration of a checker pattern for evaluating the developing
performance of a toner.
[0039] Figure 5 is a schematic illustration of an embodiment of the process-cartridge according
to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0040] As a result of our study, it has been found possible to provide a toner capable of
forming stable images while retaining a high development performance and without being
affected by an environmental change.
[0041] An azo-type iron complex, when used as a charge control agent for an electrophotographic
toner, provides a toner which shows an insufficient charging speed under a high-humidity
condition and fails to provide a sufficient image density at an initial stage or a
long period of standing under a high-humidity condition. Under a low-humidity condition,
in a long period of continual use, the toner is liable to cause an accumulation of
an excessive triboelectric charge (charge-up), thus resulting in images with a low
image density and noticeable fog.
[0042] In contrast thereto, a chromium or aluminum complex compound insoluble in a binder
resin alleviates the above-mentioned problems and has been therefore widely used.
A toner using such a chromium or aluminum complex compound is accompanied with a problem
that classified fine powder and classified coarse powder thereof cannot be readily
re-utilized. This is because the chromium or aluminum complex compound is contained
in different weight ratios in the classified fine powder, classified medium powder
(used as a toner) and classified coarse powder, so that a toner produced by re-utilization
of the classified fine powder and the classified coarse powder is liable to cause
a lowering in image density and fog during a long period of continual use in a low-humidity
environment.
[0043] We have noted in combination that an azo-type iron complex compound shows little
localization in classified powders and that a binder containing an azo-type chromium
complex compound insoluble in a binder resin shows a good developing performance,
whereby we have succeeded in improving the charge controllability of an azo-type iron
complex compound while retaining the non-localizability of the azo-type iron complex
compound, by forming micro-domains (aggregations) of the azo-type iron complex compound
in toner particles.
[0044] The formation of an azo-type iron complex compound is accomplished by the presence
of a long-chain alkyl compound in toner particles. This is considered because the
OH groups or carboxyl groups in the long-chain alkyl compound respectively form an
associated state and, under the influence of the associations, the azo-type iron complex
compound forms microdomain. As a result, the azo-type iron complex compound can be
provided with an improved charge controllability while maintaining the non-localizability.
[0045] The localization of an azo-type metal complex in classified fine powder, classified
medium powder (used as a toner) and classified coarse powder resultant after a classification
step in a toner production process using the azo-type metal complex is evaluated in
the following manner. Each powder fraction is weighed in a prescribed amount within
a range of 1.0 - 3.0 g and is dispersed in 200 ml of ethyl alcohol under stirring
for 48 hours, followed by filtration to recover a filtrate. Then, the absorption spectrum
in the visible range of the filtrate is obtained and a relative absorbance at a wavelength
showing an absorption, e.g., λ = 480 nm, attributable to the metal complex is measured.
The localization characteristic of the metal complex is evaluated by factors (ratios):
OD
F/OD
M and OD
C/OD
M, wherein OD
F denotes an absorbance of a filtrate obtained from classified fine powder, OD
M denotes an absorbance of a filtrate obtained from classified medium powder and OD
C denotes an absorbance of a filtrate obtained from classified coarse powder.
[0046] An azo-type iron complex compound represented by the above-mentioned formula (4)
wherein A
+ comprises 75 - 98 mol. % of ammonium ions, has been found to exhibit a preferred
performance in forming stable toner images. An azo-type iron complex compound having
cations consisting solely of ammonium ions tends to provide a toner showing an image
density which slowly increases after standing in a high-humidity environment. On the
other hand, an azo-type iron complex compound having cations consisting only of protons
or alkali metal ions tends to provide a toner showing a low image density in a high-humidity
environment.
[0047] As a result of our study, the use of cations including both ammonium ions and alkali
metal ions and/or protons provides a compound giving a toner showing a good performance
after a long period of standing. The inclusion of ammonium ions at 75 - 98 mol. %
provides particularly good results regarding image density increasing speed and image
density level after the increase.
[0048] When the ammonium ion content is below 75 %, the image density is lowered and, above
98 %, the image density tends to increase slowly.
[0049] As a result of further study of ours, the azo-type iron complex compound used in
the toner according to the present invention may preferably have a solubility in methanol
of 0.1 - 8 g/100 ml, more preferably 0.3 - 4 g/100 ml, further preferably 0.4 - 2
g/100 ml.
[0050] In case where the solubility is below 0.1 g/100 ml, the charge control agent (azo-type
iron complex compound) shows a low dispersibility in the toner even if the long-chain
alkyl compound is used in combination, thus providing a toner which has an unstable
triboelectric chargeability and is liable to cause image fog and scattering.
[0051] On the other hand, in case where the solubility exceeds 8 g/100 ml, the toner performances
are liable to be affected by the temperature and humidity during a long period of
standing in a high temperature - high humidity environment, so that the toner chargeability
is impaired and it becomes difficult to obtain a sufficient image density.
[0052] The charge control agent may preferably be used in a proportion of 0.2 - 5 wt. parts
per 100 wt. parts of the binder resin.
[0053] The solubility of the charge control agent may be measured in the following manner.
<Solubility measurement of charge control agent>
[0054] 2 g of a charge control agent is weighed and placed in a 300 ml Erlenmeyer flask
to which 100 ml of methanol is added. The system is heated to 50 °C under stirring
and the stirring is further continued for 1 hour (when all the charge control agent
is dissolved, the charge control agent is further added successively at an increment
of 2 g each under continued stirring). Then, the system is cooled to room temperature
and the insoluble charge control agent is removed by a 0.1 µm-filter to measure the
absorbance (A) of the solution at a maximum absorption wavelength by using a spectrophotometer.
[0055] On the other hand, a standard solution of the charge control agent (at a concentration
Co (= 0.02 g/
l (= 20 ppm)) is prepared, and the absorbance (Ao) thereof is measured. From these
data, the solubility of the charge control agent (C (g/l)) is calculated by A/Ao =
C/Co based on the Lambert-Beeis low represented by the following formula:
wherein I denotes a transmitted light intensity through a solution, I
0 denotes a transmitted light intensity through a solvent (= methanol), ε
0 denotes an absorption coefficient, C denotes the concentration of the charge control
agent, and d denotes the thickness of the solution for the absorbance measurement.
[0056] The azo-type iron complex compound used in the present invention has a structure
represented by the following general formula (4):
wherein X
1 and X
2 independently denote hydrogen atom, lower alkyl group, lower alkoxy group, nitro
group or halogen atom; m and m' denote an integer of 1 - 3; R
1 and R
3 independently denote hydrogen atom, C
1-18 alkyl or alkenyl, sufonamide, mesyl, sulfonic acid group, carboxy ester group, hydroxy,
C
1-18 alkoxy, acetylamino, benzoylamino or halogen atom; n and n' denote an integer of
1 - 3; R
2 and R
4 denote hydrogen atom or nitro group; and A
+ denotes a cation including 75 - 98 mol. % of ammonium ion and another ion selected
from the group consisting of hydrogen ion, sodium ion, potassium iron and mixtures
thereof.
[0057] The above azo-type iron complex which is suitably used as a negative charge control
agent may be synthesized according to a known process.
[0058] The negative charge control agent may be used singly or in combination of two or
more species or in combination with another negative charge control agent.
[0060] In the toner for developing the electrostatic images the azo-type ion complex may
preferably be used in an amount of 0.1 - 10 wt. parts, more preferably 0.1 - 5 wt.
parts, per 100 wt. parts of the binder resin.
[0061] The long-chain alkyl compound used in the present invention may be represented by
the following formula (1), (2) or (3).
wherein x denotes an average value in the range of 35 - 150; z denotes an average
value in the range of 1 - 5, and R denotes H or an alkyl group having 1 - 10 carbon
atoms.
[0062] The long-chain alkyl compound of the above formulae may for example be produced as
follows. Ethylene is polymerized in the presence of a Ziegler catalyst and, after
the polymerization, oxidized to provide an alkoxide of the catalyst metal and polyethylene,
which is then hydrolyzed to provide an objective long-chain alkyl compound of formula
(1). By reacting the long-chain alkyl alcohol of formula (1) with an epoxy group-containing
substance, it is possible to obtain a long-chain alkoxy alcohol of formula (2). The
thus prepared long-chain alkyl alcohols have little branching and a sharp molecular
weight distribution and are suitably used in the present invention.
wherein y denotes an integer of 35 - 150.
[0063] The long-chain alkyl compound of formula (3) may be obtained by oxidizing the long-chain
alkyl compound of formula (1).
[0064] For the compound represented by the above formula (1), (2) or (3), x and y may preferably
be 35 - 150. If x and y are below 35, the resultant toner is liable to cause melt-sticking
onto the photosensitive member or a lower storage stability. If x and y are larger
than 150, the above-mentioned contribution to toner chargeability (i.e., promoting
the formation of microdomains of the azo-type iron complex) is lowered, thus being
unsuitable for accomplishing the object of the present invention. z is preferably
at most 5. If z is larger than 5, the resultant toner is liable to cause melt-sticking
onto the photosensitive member. For similar reasons, it is preferred that R is H or
a C
1 - C
10 alkyl group.
[0065] The long-chain alkyl compound used in the present invention may suitably be a mixture
of compounds having different molecular weights and can further contain at most 30
wt. %, preferably at most 25 wt. % of hydrocarbon compounds free from functional groups
such as hydroxyl and carboxyl group as by-produced through the above-mentioned production
processes of the compounds of the formulae (1) - (3). The long-chain alkyl compound
may preferably have a number-average molecular weight (Mn) of 150 - 2500, a weight-average
molecular weight (Mw) of 250 - 5000, and an Mw/Mn ratio of at most 3.
[0066] In case where Mn is below 150 or Mw is below 250, the toner is liable to cause melt-sticking
onto the photosensitive member or a lower storage stability. In case where Mn exceeds
2500 or Mw exceeds 5000, the contribution to toner chargeability is lowered, thus
being liable to cause problems, such as fog.
[0067] The long-chain alkyl compound of formula (1) or (2) used in the present invention
may preferably have an OH value of 2 - 150 mgKOH/g, more preferably 10 - 120 mgKOH/g.
If the long-chain alkyl compound has an OH value below 2 mgKOH/g, the dispersibility
thereof in the binder resin is lowered to result in ununiform toner chargeability
leading to a density decrease, fog, and inferior image quality in copy images. In
case where the long-chain alkyl compound has an OH value exceeding 150 mgKOH/g, the
localization of the OH group charge density is increased to exceed the charge density
localization of the OH groups in the binder resin, so that copy images in the initial
state of image formation are liable to have a low density and a poor image quality.
Alternatively, even if the initial density is high, the density is liable to be lowered
gradually on continuation of copying. Further, in case where the OH value exceeds
150 mgKOH/g, the long-chain alkyl compound is caused to contain a large amount of
low-molecular weight molecules so that the resultant toner is liable to cause a melt-sticking
onto the photosensitive member and lower the storage stability.
[0068] The long-chain alkyl compound of formula (3) used in the present invention may preferably
have an acid value of 2 - 150 mgKOH/g, more preferably 5 - 120 mgKOH/g. If the long-chain
alkyl compound has an acid value below 2 mgKOH/g, the dispersion thereof in the binder
resin becomes worse, thereby resulting in inferior image qualities of copy images.
Further, as the carboxyl groups do not sufficiently associate each other, the environmental
characteristic is liable to be impaired. Further, the resultant toner is liable to
show a low charging velocity, to result in a lower density at the initial stage of
copying. In case where the acid value of the long-chain alkyl compound exceeds 150
mgKOH/g, it contains a large amount of low-molecular weight molecules, the resultant
toner is liable to cause melt-sticking onto the photosensitive member and lower the
storage stability.
[0069] The long-chain alkyl compounds, when used singly, may preferably be contained in
an amount of 0.1 - 30 wt. parts, particularly 0.5 - 20 wt. parts, per 100 wt. parts
of the binder resin.
[0070] In case where the long-chain alkyl compounds are used in combination, the total amount
thereof may preferably be 0.1 - 30 wt. parts, more preferably 0.5 - 20 wt. parts,
per 100 wt. parts of the binder resin.
[0071] It is preferred for the toner according to the present invention to contain 3 - 90
% by number of toner particles having a particle size of 5 µm or smaller. Hitherto,
it has been considered difficult to control the charge imparted to toner particles
of 5 µm or smaller. Further, such fine toner particles are considered to impair the
fluidity of the toner, soil the carrier and developing sleeve, cause cleaning failure
and filming onto the drum and scatter to soil the interior of an image forming apparatus.
Thus, it has been considered necessary to remove or decrease toner particles of 5
µm or smaller.
[0072] As a result of our study, however, in case of a toner containing a specific long-chain
alkyl compound and an azo-type iron complex of the above-mentioned formula, it has
been found that toner particles of 5 µm or smaller are very effective for providing
images of a fine definition and a high resolution.
[0073] In the toner used in the present invention, it is also preferred that toner particles
of 6.35 - 10.08 µm constitute 1 - 80 % by number and the toner has a weight-average
particle size of 4.0 - 10 µm, more preferably 4.5 - 9.0 µm.
[0074] Toner particles of 5 µm or smaller are able to strictly cover and faithfully reproduce
an electrostatic image, but an electrostatic image per se has a higher electric field
intensity at the peripheral edge than the middle or central portion. As a result,
toner particles are attached to the central portion in a smaller thickness than to
the peripheral part, so that the inner part is liable to be thin in density. We have
found that this problem can be solved to provide a clear image by using toner particles
of 6.35 - 10.08 µm in a proportion of 1 - 80 % by number. This may be attributable
to a fact that toner particles of 6.35 - 10.08 µm are supplied to an inner part having
a smaller intensity than the edge of a latent image presumably because they have a
moderately controlled charge relative to toner particles of 5 µm or smaller, thereby
to compensate for the less coverage of toner particles and result in a uniform developed
image. As a result, a sharp image having a high density and excellent in resolution
and gradation characteristic can be attained.
[0075] Further, it is most preferred that the contents of the toner particles of 5 µm or
smaller in terms of % by number (N %) and % by volume (V %) satisfy the relationship
of N/V = -0.05N+k , wherein 3 ≤ k ≤ 12, and 5 ≤ N ≤ 90. The toner having a particle
size distribution satisfying the relationship in combination with the other characteristic
features according to the present invention accomplishes a better developing performance
with respect to a digital latent image composed of minute spots.
[0076] We have found a certain state of presence of fine powder accomplishing the intended
performance satisfying the above formula during our study on the particle size distribution
with respect to particles of 5 µm or smaller. For a certain value of N, a large N/V
value is understood to mean that a large proportion of particles smaller than 5 µm
are present with a broad particle size distribution, and a small N/V value is understood
to mean that particles having a particle size in the neighborhood of 5 µm is present
in a large proportion and particles smaller than that are present in a small proportion.
A further better thin-line reproducibility and high resolution in a large quantity
of copying or printing are accomplished when the N/V is in the range of 1.0 - 7.45,
N is in the range of 5 - 90 and the above formula relationship is satisfied.
[0077] Toner particles of 12.7 µm or larger are suppressed to be not more than 2.0 % by
volume. The fewer, the better.
[0078] The particle size distribution of the toner used in the present invention is described
more specifically below.
[0079] Toner particles of 5 µm or smaller may be contained in a proportion of 5 - 90 % by
number, further preferably 9 - 75 % by number, of the total number of particles. If
the content of the toner particles of 5 µm or smaller is below 5 % by number, a portion
of the toner particles effective for providing a high image quality is few and particularly,
as the toner is consumed during a continuation of copying or printing-out, the effective
component is preferentially consumed to result in an awkward particle size distribution
of the toner and gradually deteriorates the image quality. If the content is above
90 % by number, mutual agglomeration of the toner particles and charge-up are liable
to occur, thus leading to difficulties, such as cleaning failure, a low image density,
and a large difference in density between the contour and interior of an image to
provide a somewhat hollow image.
[0080] It is preferred that the content of the particles in the range of 6.35 - 10.08 µm
is 1 - 80 % by number, further preferably 5 - 70 % by number. Above 80 % by number,
the image quality becomes worse, and excess of toner coverage is liable to occur,
thus resulting in a lower thin-line reproducibility and an increased toner consumption.
Below 5 % by number, it becomes difficult to obtain a high image density in some cases.
[0081] For similar reasons as N, V may preferably be 0.5 - 70 % by volume.
[0082] The
k value may preferably be 3 - 12, more preferably 4 - 10.
[0083] If
k < 3.0, toner particles of 5.0 µm or below are insufficient, and the resultant image
density, resolution and sharpness decrease. When fine toner particles in a toner,
which have conventionally been considered useless, are present in an appropriate amount,
they are effective for achieving closest packing of toner in development and contribute
to the formation of a uniform image. Particularly, these particles fill thin-line
portions and contour portions of an image, thereby to visually improve the sharpness
thereof. On the other hand, if k > 12, an excess of fine powder is present, whereby
the balance of particle size distribution can be disturbed during successive copying
or print-out, thus leading to difficulties such as a somewhat lower image density
and filming.
[0084] The amount of toner particles having a particle size of 12.7 µm or larger should
be 2.0 % by volume or smaller, preferably 1.0 % by volume or smaller, more preferably
0.5 % by volume or smaller. If the above amount is larger than 2.0 % by volume, these
particles are liable to impair thin-line reproducibility.
[0085] The toner used in the present invention may have a weight-average particle size of
4 - 10 µm, more preferably 4.5 - 9 µm. This value cannot be considered separately
from the above-mentioned factors. If the weight-average particle size is below 4 µm,
the toner is liable to cause soiling of the interior of an apparatus with scattered
toner, a lowering in image density in a low-humidity environment and cleaning failure
of the photosensitive member. If the weight-average particle size exceeds 9 µm, a
minute spot of 100 µm or smaller cannot be developed with a sufficient resolution
and noticeable scattering to non-image part is observed, thus being liable to provide
inferior images.
[0086] Examples of the binder resin used in the toner of the present invention may include
polyester resins, vinyl resins and epoxy resins. Among these, polyester resins or
vinyl resins may preferably be used in view of charging characteristic and fixing
characteristic.
[0087] A polyester resin preferably used in the present invention may have a composition
that it comprises 45 - 55 mol. % of alcohol component and 55 - 45 mol. % of acid component.
[0088] Examples of the alcohol component may include: diols, such as ethylene glycol, propylene
glycol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene
glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-ethyl-1,3-hexanediol,
hydrogenated bisphenol A, bisphenols and derivatives represented by the following
formula (A):
wherein R denotes an ethylene or propylene group, x and y are independently a positive
integer of at least 1 with the proviso that the average of x+y is in the range of
2 - 10; diols represented by the following formula (B):
wherein R' denotes -CH
2CH
2-,
x' and y' are a positive integer of at least 1 with the proviso that the average
of x'+y' is in the range of 1 - 10.
[0089] Examples of the dibasic acid constituting at least 50 mol. % of the total acid may
include benzenedicarboxylic acids, such as phthalic acid, terephthalic acid and isophthalic
acid, and their anhydrides; alkyldicarboxylic acids, such as succinic acid, adipic
acid, sebacic acid and azelaic acid, and their anhydrides; C
6 - C
18 alkyl or alkenyl-substituted succinic acids, and their anhydrides; and unsaturated
dicarboxylic acids, such as fumaric acid, maleic acid, citraconic acid and itaconic
acid, and their anhydrides.
[0090] An especially preferred class of alcohol components constituting the polyester resin
is a bisphenol derivative represented by the above formula (A), and preferred examples
of acid components may include dicarboxylic acids inclusive of phthalic acid, terephthalic
acid, isophthalic acid and their anhydrides; succinic acid, n-dodecenylsuccinic acid,
and their anhydrides, fumaric acid, maleic acid, and maleic anhydride.
[0091] The polyester resin may preferably have a glass transition temperature of 40 - 90
°C, particularly 45 - 85 °C, a number-average molecular weight (Mn) of 1,000 - 50,000,
particularly 1,500 - 20,000, and a weight-average molecular weight (Mw) of 3x10
3 - 5x10
6, particularly 4x10
3 - 1.5x10
6.
[0092] Examples of a vinyl monomer for providing the vinyl resin may include: styrene; styrene
derivatives, such as o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene,
p-phenylstyrene, p-chlorostyrene, 3,4-dichlorostyrene, p-ethylstyrene, 2,4-dimethylstyrene,
p-n-butylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene,
p-n-decylstyrene, and p-n-dodecylstyrene; ethylenically unsaturated monoolefins, such
as ethylene, propylene, butylene, and isobutylene; unsaturated polyenes, such as butadiene;
halogenated vinyls, such as vinyl chloride, vinylidene chloride, vinyl bromide, and
vinyl fluoride; vinyl esters, such as vinyl acetate, vinyl propionate, and vinyl benzoate;
methacrylates, such as methyl methacrylate, ethyl methacrylate, propyl methacrylate,
n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate,
2-ethylhexyl methacrylate, stearyl methacrylate, phenyl methacrylate, dimethylaminoethyl
methacrylate, and diethylaminoethyl methacrylate; acrylates, such as methyl acrylate,
ethyl acrylate, n-butyl acrylate, isobutyl acrylate, propyl acrylate, n-octyl acrylate,
dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, 2-chloroethyl acrylate,
and phenyl acrylate, vinyl ethers, such as vinyl methyl ether, vinyl ethyl ether,
and vinyl isobutyl ether; vinyl ketones, such as vinyl methyl ketone, vinyl hexyl
ketone, and methyl isopropenyl ketone; N-vinyl compounds, such as N-vinylpyrrole,
N-vinylcarbazole, N-vinylindole, and N-vinyl pyrrolidone; vinylnaphthalenes; acrylic
acid derivatives or methacrylic acid derivatives, such as acrylonitrile, methacryronitrile,
and acrylamide; the esters of the above-mentioned α,β-unsaturated acids and the diesters
of the above-mentioned dibasic acids.
[0093] Examples of a carboxy group-containing vinyl monomer may include: unsaturated dibasic
acids, such as maleic acid, citraconic acid, itaconic acid, alkenylsuccinic acid,
fumaric acid, and mesaconic acid; unsaturated dibasic acid anhydrides, such as maleic
anhydride, citraconic anhydride, itaconic anhydride, and alkenylsuccinic anhydride;
unsaturated dibasic acid half esters, such as mono-methyl maleate, mono-ethyl maleate,
mono-butyl maleate, mono-methyl citraconate, mono-ethyl citraconate, mono-butyl citraconate,
mono-methyl itaconate, mono-methyl alkenylsuccinate, monomethyl fumarate, and mono-methyl
mesaconate; unsaturated dibasic acid esters, such as dimethyl maleate and dimethyl
fumarate; α,β-unsaturated acids, such as acrylic acid, methacrylic acid, crotonic
acid, and cinnamic acid; α,β-unsaturated acid anhydrides, such as crotonic anhydride,
and cinnamic anhydride; anhydrides between such an α,β-unsaturated acid and a lower
aliphatic acid; alkenylmalonic acid, alkenylglutaric acid, alkenyladipic acid, and
anhydrides and monoesters of these acids.
[0094] It is also possible to use a hydroxyl group-containing vinyl monomer: inclusive of
acrylic or methacrylic acid esters, such as 2-hydroxyethyl acrylate, and 2-hydroxyethyl
methacrylate; 4-(1-hydroxy-1-methylbutyl)styrene, and 4-(1-hydroxy-1-methylhexyl)styrene.
[0095] The vinyl resin may have a glass transition point of 45 - 80 °C, preferably 55 -
70 °C, a number-average molecular weight (Mn) of 2.5x10
3 - 5x10
4, and a weight-average molecular weight (Mw) of 1x10
4 - 1.5x10
6.
[0096] In the present invention, it is also possible to use a mixture binder resin including
a vinyl homopolymer or copolymer, a polyester, polyester, epoxy resin, polyvinyl butyral,
rosin, modified rosin, terpene resin, phenolic resin, aliphatic or alicyclic-hydrocarbon
resin or aromatic petroleum resin, in addition to the above-mentioned binder resin.
[0097] In case of using a mixture binder resin including two or more resins of the same
or different types, the two or more resins may preferably have different molecular
weights and may be mixed with each other in appropriate ratios.
[0098] The toner according to the present invention may be either a magnetic toner or a
non-magnetic toner. In order to constitute a magnetic toner, it is preferred to use
a magnetic material as described below.
[0099] Examples of the magnetic material contained in the insulating magnetic toner used
in the present invention may include: iron oxides, such as magnetite, hematite, and
ferrite; iron oxides containing another metal oxide; metals, such as Fe, Co and Ni,
and alloys of these metals with other metals, such as Al, Co, Cu, Pb, Mg, Ni, Sn,
Zn, Sb, Be, Bi, Cd, Ca, Mn, Se, Ti, W and V; and mixtures of the above.
[0100] Specific examples of the magnetic material may include: triiron tetroxide (Fe
3O
4), diiron trioxide (γ-Fe
2O
3), zinc iron oxide (ZnFe
2O
4), yttrium iron oxide (Y
3Fe
5O
12), cadmium iron oxide (CdFe
2O
4), gadolinium iron oxide (Gd
3Fe
5O
12), copper iron oxide (CuFe
2O
4), lead iron oxide (PbFe
12O
19), nickel iron oxide (NiFe
2O
4), neodymium iron oxide (NdFe
2O
3), barium iron oxide (BaFe
12O
19), magnesium iron oxide (MgFe
2O
4), manganese iron oxide (MnFe
2O
4), lanthanum iron oxide (LaFeO
3), powdery iron (Fe), powdery cobalt (Co), and powdery nickel (Ni). The above magnetic
materials may be used singly or in mixture of two or more species. Particularly suitable
magnetic material for the present invention is fine powder of triiron tetroxide or
γ-diiron trioxide.
[0101] The magnetic material may have an average particle size (Dav.) of 0.1 - 2 µm, preferably
0.1 - 0.3 µm. The magnetic material may preferably show magnetic properties when measured
by application of 10 kilo-Oersted, inclusive of: a coercive force (Hc) of 20 - 150
Oersted, a saturation magnetization (as) of 50 - 200 emu/g, particularly 50 - 100
emu/g, and a residual magnetization (σr) of 2 - 20 emu/g.
[0102] The magnetic material may be contained in the toner in a proportion of 10 - 200 wt.
parts, preferably 20 - 150 wt. parts, per 100 wt. parts of the binder resin.
[0103] The toner according to the present invention may optionally contain a colorant, inclusive
of arbitrary pigments or dyes.
[0104] Examples of the pigment may include: carbon black, aniline black, acetylene black,
Naphthol Yellow, Hansa Yellow, Rhodamine Lake, Alizarine Lake, red iron oxide, Phthalocyanine
Blue, and Indanthrene Blue. It is preferred to use 0.1 - 20 wt. parts, particularly
1 - 10 wt. parts, of a pigment per 100 wt. parts of the binder resin. For similar
purpose, there may also be used dyes, such as azo dyes, anthraquinone dyes, xanthene
dyes, and methine dyes, which may preferably be used in an amount of 0.1 - 20 wt.
parts, particularly 0.3 - 10 wt. parts, per 100 wt. parts of the resin.
[0105] In the present invention, it is also possible to incorporate one or two or more species
of release agent, as desired, within a toner.
[0106] Examples of the release agent may include: aliphatic hydrocarbon waxes, such as low-molecular
weight polyethylene, low-molecular weight polypropylene, microcrystalline wax, and
paraffin wax, oxidation products of aliphatic hydrocarbon waxes, such as oxidized
polyethylene wax, and block copolymers of these; waxes containing aliphatic esters
as principal constituents, such as carnauba wax, montanic acid ester wax, and partially
or totally deacidified aliphatic esters, such as deacidified carnauba wax. Further
examples of the release agent may include: saturated linear aliphatic acids, such
as palmitic acid, stearic acid, and montanic acid; unsaturated aliphatic acids, such
as brassidic acid, eleostearic acid and parinaric acid; saturated alcohols, such as
stearyl alcohol, behenyl alcohol, ceryl alcohol, and melissyl alcohol; polyhydric
alcohols, such as sorbitol; aliphatic acid amides, such as linoleylamide, oleylamide,
and laurylamide; saturated aliphatic acid bisamides, methylene-bisstearylamide, ethylene-biscaprylamide,
and ethylene-biscaprylamide; unsaturated aliphatic acid amides, such as ethylene-bisolerylamide,
hexamethylene-bisoleylamide, N,N'-dioleyladipoylamide, and N,N'-dioleylsebacoylamide,
aromatic bisamides, such as m-xylene-bisstearoylamide, and N,N'-distearylisophthalylamide;
aliphatic acid metal salts (generally called metallic soap), such as calcium stearate,
calcium laurate, zinc stearate, and magnesium stearate; grafted waxes obtained by
grafting aliphatic hydrocarbon waxes with vinyl monomers, such as styrene and acrylic
acid; partially esterified products between aliphatic acids and polyhydric alcohols,
such as behenic acid monoglyceride; and methyl ester compounds having hydroxyl group
as obtained by hydrogenating vegetable fat and oil.
[0107] The particularly preferred class of release agent in the present invention may include
aliphatic hydrocarbon waxes because of good dispersibility within the binder resin
(preferably one having an acid value of 5 - 50), thus providing not only a good fixability
of the resultant toner but also a minimum abrasion of an organic photoconductor when
used in combination with the toner according to the present invention.
[0108] Specific examples of the release agent preferably used in the present invention may
include e.g., a low-molecular weight alkylene polymer obtained through polymerization
of an alkylene by radical polymerization under a high pressure or in the presence
of a Ziegler catalyst under a low pressure; an alkylene polymer obtained by thermal
decomposition of an alkylene polymer of a high molecular weight; and a hydrocarbon
wax obtained by subjecting a mixture gas containing carbon monoxide and hydrogen to
the Arge process to form a hydrocarbon mixture and distilling the hydrocarbon mixture
to recover a residue. Fractionation of wax may preferably be performed by the press
sweating method, the solvent method, vacuum distillation or fractionating crystallization.
As the source of the hydrocarbon wax, it is preferred to use hydrocarbons having up
to several hundred carbon atoms as obtained through synthesis from a mixture of carbon
monoxide and hydrogen in the presence of a metal oxide catalyst (generally a composite
of two or more species), e.g., by the Synthol process, the Hydrocol process (using
a fluidized catalyst bed), and the Arge process (using a fixed catalyst bed) providing
a product rich in waxy hydrocarbon, and hydrocarbons obtained by polymerizing an alkylene,
such as ethylene, in the presence of a Ziegler catalyst, as they are rich in saturated
long-chain linear hydrocarbons and accompanied with few branches. It is further preferred
to use hydrocarbon waxes synthesized without polymerization because of their structure
and molecular weight distribution suitable for easy fractionation.
[0109] As for the molecular weight distribution of the wax, it is preferred that the wax
shows a peak in a molecular weight region of 400 - 2400, further 450 - 2000, particularly
500 - 1600. By satisfying such molecular weight distribution, the resultant toner
is provided with preferable thermal characteristics.
[0110] The release agent may preferably be used in an amount of 0.1 - 20 wt. parts, particularly
0.5 - 10 wt. parts, per 100 wt. parts of the binder resin.
[0111] The release agent may be uniformly dispersed in the binder resin by a method of mixing
the release agent in a solution of the resin at an elevated temperature under stirring
or melt-kneading the binder resin together with the release agent.
[0112] A flowability-improving agent may be optionally blended with the toner to improve
the flowability of the toner. Examples thereof may include: powder of fluorine-containing
resin, such as polyvinylidene fluoride fine powder and polytetrafluoroethylene fine
powder; titanium oxide fine powder, hydrophobic titanium oxide fine powder; fine powdery
silica such as wet-process silica and dry-process silica, and treated silica obtained
by surface-treating such fine powdery silica with silane coupling agent, titanium
coupling agent, silicone oil, etc.
[0113] A preferred class of the flowability-improving agent includes dry process silica
or fumed silica obtained by vapor-phase oxidation of a silicon halide. For example,
silica powder can be produced according to the method utilizing pyrolytic oxidation
of gaseous silicon tetrachloride in oxygen-hydrogen flame, and the basic reaction
scheme may be represented as follows:
[0114] In the above preparation step, it is also possible to obtain complex fine powder
of silica and other metal oxides by using other metal halide compounds such as aluminum
chloride or titanium chloride together with silicon halide compounds. Such is also
included in the fine silica powder to be used in the present invention.
[0115] It is preferred to use fine silica powder having an average primary particle size
of 0.001 - 2 µm, particularly 0.002 - 0.2 µm.
[0116] Commercially available fine silica powder formed by vapor phase oxidation of a silicon
halide to be used in the present invention include those sold under the trade names
as shown below.
AEROSIL (Nippon Aerosil Co.) |
130 |
200 |
300 |
380 |
TT 600 |
MOX 170 |
MOX 80 |
COK 84 |
Cab-O-Sil (Cabot Co.) |
M-5 |
MS-7 |
MS-75 |
HS-5 |
EH-5 |
Wacker HDK (WACKER-CHEMIE GMBH) |
N 20 |
|
V 15 |
N 20E |
T 30 |
T 40 |
D-C Fine Silica (Dow Corning Co.) |
|
Fransol (Fransil Co.) |
|
[0117] It is further preferred to use treated silica fine powder obtained by subjecting
the silica fine powder formed by vapor-phase oxidation of a silicon halide to a hydrophobicity-imparting
treatment. It is particularly preferred to use treated silica fine powder having a
hydrophobicity of 30 - 80 as measured by the methanol titration test.
[0118] Silica fine powder may be imparted with a hydrophobicity by chemically treating the
powder with an organosilicone compound, etc., reactive with or physically adsorbed
by the silica fine powder.
[0119] Example of such an organosilicone compound may include: hexamethyldisilazane, trimethylsilane,
trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane,
allyldimethylchlorosilane, allylphenyldichlorosilane, benzyldimethylcholrosilane,
bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane,
chloromethyldimethylchlorosilane, triorganosilylmercaptans such as trimethylsilylmercaptan,
triorganosilyl acrylates, vinyldimethylacetoxysilane, dimethylethoxysilane, dimethyldimethoxysilane,
diphenyldiethoxysilane, hexamethyldisiloxane, 1,3-divinyltetramethyldisiloxane, 1,3-diphenyltetramethyldisiloxane,
and dimethylpolysiloxane having 2 to 12 siloxane units per molecule and containing
each one hydroxyl group bonded to Si at the terminal units. These may be used alone
or as a mixture of two or more compounds.
[0120] The flowability-improving agent used in the present invention may have a specific
surface area of at least 30 m
2/g, preferably 50 m
2/g, as measured by the BET method according to nitrogen adsorption. The flowability-improving
agent may be used in an amount of 0.01 - 8 wt. parts, preferably 0.1 - 4 wt. parts,
per 100 wt. parts of the toner.
[0121] In case where the toner according to the present invention is used for constituting
a two-component type developer, the toner is blended with a carrier. Examples of the
carrier used in the present invention may include: surface-oxidized or -unoxidized
powder of metals, such as iron, nickel, copper, zinc, cobalt, manganese, chromium
and rare earth metals, particles of alloys of these metal, oxide particles, and ferrite
particles.
[0122] A coated carrier obtained by coating the above carrier particles with a resin may
preferably be used particularly in a developing method wherein a developing bias is
supplied with an AC bias voltage. The coating may be performed according to known
methods inclusive of a method applying a coating liquid obtained by dissolving or
suspending a coating material such as a resin into a solvent onto the surface of carrier
core particles, and a method of powder blending carrier core particles and a coating
material.
[0123] Examples of the coating material firmly applied onto the core particles may include:
polytetrafluoroethylene, monochlorotrifluoroethylene polymer, polyvinylidene fluoride,
silicone resin, polyester resin, styrene resin, acrylic resin, polyamide, polyvinyl
butyral, aminoacrylate resin, basic dyes and lakes thereof, silica fine powder and
alumina fine powder. These coating materials may be used singly or in combination
of plural species.
[0124] The coating material may be applied onto the core particles in a proportion of 0.1
- 30 wt. %, preferably 0.5 - 20 wt. %, based on the carrier core particles. The carrier
may preferably have an average particle size of 10 - 100 µm, more preferably 20 -
70 µm.
[0125] A particularly preferred type of carrier may comprise particles of a magnetic ferrite
such as Cu-Zn-Fe ternary ferrite surface-coated with a fluorine-containing resin or
a styrene-based resin. Preferred coating materials may include mixtures of a fluorine
containing resin and a styrene copolymer, such as a mixture of polyvinylidene fluoride
and styrene-methyl methacrylate resin, and a mixture of polytetraluforoethylene and
styrene-methyl methacrylate resin. The fluorine-containing resin may also be a copolymer,
such as vinylidene fluoride/tetrafluoroethylene (10/90 - 90/10) copolymer. Other examples
of the styrene-based resin may include styrene/2-ethylhexyl acrylate (20/80 - 80/20)
copolymer and styrene/2-ethylhexyl acrylate/methyl methacrylate (20 - 60/5 - 30/10
- 50) copolymer. The fluorine-containing resin and the styrene-based resin may be
blended in a weight ratio of 90:10 - 20:80, preferably 70:30 - 30:70. The coating
amount may be 0.01 - 5 wt. %, preferably 0.1 - 1 wt. % of the carrier core.
[0126] The coated magnetic ferrite carrier may preferably include at least 70 wt. % of particles
of 250 mesh-pass and 400 mesh-on, and have an average particle size of 10 - 100 µm,
more preferably 20 - 70 µm. A sharp particle size distribution is preferred.
[0127] The characteristic values of a binder resin and a long-chain alkyl compound and the
particle size distribution of a toner referred to herein may be measured according
to the following methods.
(1) Glass transition temperature Tg
[0128] Measurement may be performed in the following manner by using a differential scanning
calorimeter ("DSC-7", available from Perkin-Elmer Corp.).
[0129] A sample in an amount of 5 - 20 mg, preferably about 10 mg, is accurately weighed.
[0130] The sample is placed on an aluminum pan and subjected to measurement in a temperature
range of 30 - 200 °C at a temperature-raising rate of 10 °C/min in a normal temperature
- normal humidity environment in parallel with a blank aluminum pan as a reference.
[0131] In the course of temperature increase, a main absorption peak appears in the temperature
region of 40 - 100 °C.
[0132] In this instance, the glass transition temperature is determined as a temperature
of an intersection between a DSC curve and an intermediate line pressing between the
base lines obtained before and after the appearance of the absorption peak.
(2) Molecular weight distribution (for binder resin)
[0133] The molecular weight (distribution) of a binder resin may be measured based on a
chromatogram obtained by GPC (gel permeation chromatography).
[0134] In the GPC apparatus, a column is stabilized in a heat chamber at 40 °C, tetrahydrofuran
(THF) solvent is caused to flow through the column at that temperature at a rate of
1 ml/min., and 50 - 200 µl of a GPC sample solution adjusted at a concentration of
0.05 - 0.6 wt. % is injected. The identification of sample molecular weight and its
molecular weight distribution is performed based on a calibration curve obtained by
using several monodisperse polystyrene samples and having a logarithmic scale of molecular
weight versus count number. The standard polystyrene samples for preparation of a
calibration curve may be available from, e.g., Pressure Chemical Co. or Toso K.K.
It is appropriate to use at least 10 standard polystyrene samples inclusive of those
having molecular weights of, e.g., 6x10
2, 2.1x10
3, 4x10
3, 1.75x10
4, 5.1x10
4, 1.1x10
5, 3.9x10
5, 8.6x10
5, 2x10
6 and 4.48x10
6. The detector may be an RI (refractive index) detector. For accurate measurement,
it is appropriate to constitute the column as a combination of several commercially
available polystyrene gel columns in order to effect accurate measurement in the molecular
weight range of 10
3 - 2x10
6. A preferred example thereof may be a combination of µ-styragel 500, 10
3, 10
4 and 10
5 available from Waters Co.; a combination of Shodex KF-801, 802, 803, 804, 805, 806
and 807 available from Showa Denko K.K.
(3) Molecular weight distribution (for long-chain alkyl compound)
[0135] The molecular weight (distribution) of a long-chain alkyl compound may be measured
by GPC under the following conditions:
Apparatus: "GPC-150C" (available from Waters Co.)
Column: "GMH-HT" 30 cm-binary (available from Toso K.K.)
Temperature: 135 oC
Solvent: o-dichlorobenzene containing 0.1 % of ionol.
Flow rate: 1.0 ml/min.
Sample: 0.4 ml of a 0.15 %-sample.
[0136] Based on the above GPC measurement, the molecular weight distribution of a sample
is obtained once based on a calibration curve prepared by monodisperse polystyrene
standard samples, and recalculated into a distribution corresponding to that of polyethylene
using a conversion formula based on the Mark-Houwink viscosity formula.
(4) Measurement of acid values and OH values
1) re: Acid value
[0137] A sample material is accurately weighed and dissolved in a mixture solvent, and water
is added thereto. The resultant liquid is titrated with 0.1N-NaOH by potentiometric
titration using glass electrodes (according to JIS K1557-1970).
2) re: Hydroxyl value (OH value)
[0138] A sample is accurately weighed into a 100 ml-volumetric flask, and 5 ml of an acetylating
agent is accurately added thereto. Then, the system is heated by dipping into a bath
of 100
oC ± 5 °C. After 1 - 2 hours, the flask is taken out of the bath and allowed to cool
by standing, and water is added thereto, followed by shaking to decompose acetic anhydride.
In order to complete the decomposition, the flask is again heated for more than 10
min. by dipping into the bath. After cooling, the flask wall is sufficiently washed
with an organic solvent. The resultant liquid is titrated with a N/2-potassium hydroxide
solution in ethyl alcohol by potentiometric titration using glass electrodes (according
to JIS K0070-1966).
(5) Particle size distribution measurement
[0139] Coulter Multisizer II (available from Coulter Electronics Inc.) is used as an instrument
for measurement, to which an interface (available from Nikkaki K.K.) for providing
a number-basis distribution, and a volume-basis distribution and a personal computer
PC 9801 (available from NEC K.K.) are connected.
[0140] For measurement, a 1 %-NaCl aqueous solution as an electrolytic solution is prepared
by using a reagent-grade sodium chloride. Into 100 to 150 ml of the electrolytic solution,
0.1 to 5 ml of a surfactant (preferably an alkylbenzenesulfonic acid salt) is added
as a dispersant, and 2 to 20 mg of a sample is added thereto. The resultant dispersion
of the sample in the electrolytic liquid is subjected to a dispersion treatment for
about 1 - 3 minutes by means of an ultrasonic disperser, and then subjected to measurement
of particle size distribution in the range of 2 - 40 µm by using the above-mentioned
Coulter Multisizer II with a 100 micron-aperture to obtain a volume-basis distribution
and a number-basis distribution. Form the results of the volume-basis distribution
and number-basis distribution in the range of 2 - 40 µm, a weight-average particle
size (D4) is calculated with a central value of each channel taken as a representative
value of the channel.
[0141] Next, an embodiment of the image forming method according to the present invention
will be described with reference to Figures 1 - 3. Figure 1 shows an electrophotographic
apparatus usable as an example of a copying machine or a printer for practicing the
image forming method according to the present invention. The apparatus includes a
developing means 1 containing a toner 13 according to the present invention. The toner
may be a magnetic toner or a non-magnetic toner. In an image forming apparatus other
than the one shown in Figure 1, it is possible to use a developing means including
a two-component type developer comprising a toner and a carrier.
[0142] Referring again to Figure 1, the surface of a photosensitive member 3 (e.g., an OPC
photosensitive drum, an amorphous silicon photosensitive drum or a polysilicon photosensitive
drum) is charged by a charging means 11 (e.g., a contact charging means such as a
charging roller as shown, a charging brush or a charging blade) supplied with a voltage
from a bias voltage application means 34. Then, the charged surface of the photosensitive
member 3 is irradiated with light 5 (e.g., laser light or light from a halogen lamp)
carrying image data to form an electrostatic image on the photosensitive member. The
electrostatic image is developed with a magnetic toner 13 (in this embodiment) on
a developing sleeve 6 enclosing a magnetic field generating means 15 (e.g., a magnet)
of the developing means 1 also equipped with a toner applicator blade 8 (e.g., an
elastic blade or a magnetic blade) for applying the toner 13 onto the developing sleeve
6. The development is performed by either the normal development scheme or the reversal
development scheme to form a toner image on the photosensitive member 3. At the developing
station, the developing sleeve may be supplied, as desired, with an alternating, a
pulse, and/or a DC bias voltage from a bias voltage application means 12. When the
toner image on the photosensitive member 3 arrives at a transfer station to which
also a transfer material is conveyed, the back side (side opposite the photosensitive
member 3) of the transfer member P is pressed and charged by a transfer means 4 (e.g.,
a transfer roller as shown or a transfer belt) to which a voltage is applied from
a bias application means 33, to electrostatically transfer the toner image on the
photosensitive member 3 onto the transfer material P. As the case may be, the toner
image on the photosensitive member 3 can be transferred onto an intermediate transfer
member (not shown, such as an intermediate transfer drum or an intermediate transfer
belt) and then to the transfer material P.
[0143] The toner image on the transfer material P separated from the photosensitive member
3 may be fixed onto the transfer material P by a heat-and-pressure application means
35 (e.g., a fixing means as shown wherein a pressure roller 23 is pressed against
a fixed heat-generating member 21 via a heat-resistant sheet 22; or a heat-pressure
roller fixing means). A portion, if any, of the toner remaining on the photosensitive
member 3 after the transfer step may be removed, as desired, from the surface of the
photosensitive member 3 by a cleaning means 7 (e.g., a cleaning blade as shown, a
cleaning roller or a cleaning brush). The photosensitive member 3 after the cleaning
is again subjected to an image forming cycle as described above starting from the
charging step by the charging means 11.
[0144] The photosensitive member 3 as a member to be charged and also an electrostatic image-bearing
member generally comprises a photosensitive layer and an electroconductive substrate
and is rotated in the direction of an arrow as indicated. The developing sleeve 6
comprising a non-magnetic cylinder as a toner carrying member is rotated in the same
direction as the photosensitive member 3 at the developing station. Inside the developing
sleeve 6, a multi-polar permanent magnet (magnet roll) 15 as a magnetic field-generating
means is fixedly disposed. The magnetic toner 13 contained inside the developing means
1 is applied by the applicator blade 8 onto the surface of the developing sleeve,
and the toner particles constituting the toner are triboelectrically charged by friction
with the applicator blade 8 and/or the developing sleeve 6. The toner may be uniformly
applied by the applicator blade 8 in a layer of e.g., 10 - 300 µm on the surface of
the developing sleeve 6. At the developing station, the developing sleeve 6 may be
supplied with an AC bias voltage of f = 200 - 4000 Hz and Vpp = 500 - 3000 V.
[0145] At the developing station, toner particles are transferred onto the electrostatic
image on the photosensitive member due to the electrostatic force of the photosensitive
member surface and the action of an AC or pulse bias voltage.
[0146] Incidentally, in Examples described hereinafter, an image forming apparatus having
structure as shown in Figures 1 to 3 was used, of which the included members are denoted
by reference numerals as shown below.
[0147] That is, reference numeral 3 denotes an electrostatic image-bearing member (photosensitive
drum); 11, a charger (charging roller); 2, a process-cartridge; 7, a cleaning means;
5, an exposure means; 15, a developer container; 6, a developer-carrying member (developing
sleeve); 15, a magnetic field generating means; 8, a layer thickness-regulating elastic
member; 4, a transfer means (transfer roller); 20, a stay; 21, a heating member; 21a,
a heater substrate; 21b, a heat-generating member; 21c, a surface protective layer;
21d, a temperature-detecting element; 22, a fixing film; 23, a pressing roller; 24,
a coil spring; 25, a film edge-regulating member; 26, an electricity-supplying connector;
27, an electricity interrupting member; 28, an inlet guide; and 29, an outlet guide
(separation guide).
[0148] Further, Figure 5 is a schematic sectional view of a process-cartridge detached from
a main body of an image forming apparatus as described above. The process-cartridge
at least includes a developing means and an electrostatic image-bearing member which
are integrated into a cartridge, so as to be detachably mountable to a main body of
an image forming apparatus, such as a copying machine or a laser beam printer.
[0149] In this embodiment shown in Figure 5, the process-cartridge integrally includes a
developing means 1, a drum-shaped electrostatic image bearing member (photosensitive
drum) 3, a cleaner including a cleaning blade 7, and a primary charger (charging roller)
11.
[0150] In this embodiment, the developing means 1 includes a toner layer thickness-regulating
member 8 and a toner vessel containing a magnetic toner 13. At the time of development,
a prescribed bias electric field is applied between the photosensitive drum 3 and
the developing sleeve 6 carrying the magnetic toner 13 to effect a development of
an electrostatic image formed on the photosensitive drum 3.
[0151] Hereinbelow, the present invention will be described based on specific Examples.
Resin Production Example 1
[0152]
Terephthalic acid |
12 mol. % |
Fumaric acid |
18 mol. % |
Adipic acid |
10 mol. % |
Trimellitic anhydride |
12 mol. % |
Bisphenol derivatives of the above-described formula (A) |
|
(R = propylene, x + y = 2.2) |
15 mol. % |
(R = ethylene, x + y = 2.2) |
33 mol. % |
[0153] The above ingredients were subjected to polycondensation to obtain a polyester (called
"Resin A") having Mn = 5,000, Mw = 57,000, Tg = 60 °C, acid value = 20, OH value =
20.
Resin Production Example 2
[0154]
Styrene |
87 wt.parts |
Butyl acrylate |
13 " |
Di-tert-butyl peroxide |
3 " |
[0155] The above ingredients were added dropwise in 4 hours to 200 wt. parts of xylene heated
to the reflux temperature. Further, the polymerization was completed under xylene
reflux (138 - 144 °C), followed by heating to 200 °C under a reduced pressure to remove
the xylene. The thus-obtained resin is called "Resin B".
Styrene |
75 wt.part (s) |
Butyl acrylate |
25 " |
2,2-Bis(4,4-di-tert-butylperoxycyclohexyl)propane |
0.1 " |
Benzoyl peroxide |
0.1 " |
[0156] To a mixture liquid comprising the above ingredients, 170 wt. parts of water containing
0.12 wt. part of partially saponified polyvinyl alcohol was added, and the system
was vigorously stirred to form a suspension liquid. The suspension liquid was added
to a reaction vessel containing 50 wt. parts of water and aerated with nitrogen, and
was subjected to suspension polymerization at 80 °C for 8 hours. After the reaction,
the product was washed to obtain Resin C.
[0157] The above Resin B and Resin C at a weight ratio of 70:30 were dissolved in xylene
and uniformly mixed, followed by removal of xylene to obtain Resin D, which showed
a molecular weight distribution providing peaks at molecular weights of 1.2x10
4 and 8x10
5, Mn (number-average molecular weight) = 0.7x10
4 and Mw (weight-average molecular weight) = 2.5x10
5, and Tg = 61 °C.
Resin Production Example 3
[0158]
Styrene |
80.0 wt.parts |
Butyl acrylate |
10.0 " |
Monobutyl maleate |
10.0 " |
Di-tert-butyl peroxide |
6.0 " |
[0159] Resin E was prepared from the above ingredients otherwise in the same manner as in
production of Resin B in Resin Production Example 2 above.
Resin E |
40.0 wt.part(s) |
Styrene |
45.0 " |
Butyl acrylate |
15.0 " |
Divinylbenzene |
0.5 " |
Benzoyl peroxide |
0.5 " |
[0160] A mixture liquid comprising the above ingredients was subjected to suspension polymerization
in the same manner as in production of Resin C in Resin Production Example 2 to obtain
Resin F, which showed Tg = 60 °C, Mn = 1x10
4 and Mw = 1x10
5.
Example 1
[0161]
Resin A |
100 wt.parts |
Magnetic iron oxide (average particle size (Dav.) = 0.15 µm, Hc = 115 oersted, σs = 80 emu/g, σr = 11 emu/g) |
90 wt.parts |
Long-chain alkyl alcohol of Formula (1) (x = 48 as an average value, Mn = 440, Mw
= 870, Mw/Mn = 1.98, OH value = 66) |
3 wt.parts |
Azo-type iron complex (1) (A+ = 90 %:NH4, 10 %:Na+ and H+ mixture; SMeOH (solubility in methanol) = 0.87 g/100 ml) |
2 wt.% |
[0162] The above ingredients were pre-mixed by a Henschel mixer and melt-kneaded through
a twin screw extruder at 130 °C. After cooling, the melt-kneaded product was coarsely
crushed by a cutter mill, pulverized by a jet stream pulverizer, and classified by
a pneumatic classifier to obtain a magnetic toner (1) having a weight-average particle
size (D
4) of 6.6 µm, content of ≦ 5 µm particles: 49.3 % (N, % by number), 9.6 % (V, % by
volume). The characterizing data of the toner are summarized in Table 1.
[0163] The localization factors of the azo-type iron complex in the fine and coarse power
fractions were OD
F/OD
M = 1.012 and OD
G/OD
M = 0.998.
[0164] 100 wt. parts of the magnetic toner (1) and 1.0 wt. part of hydrophobic silica surface-treated
with hexamethyldisilazane were blended in a Henschel mixer to obtain Developer No.
1.
[0165] The thus-obtained Developer No. 1 was charged in a commercially available digital
copying machine ("GP-55", available from Canon K.K.) and subjected to image formation
of 5x10
4 sheets under normal temperature/low humidity (N/L = 23.5 °C/5 %RH) conditions and
further 3x10
4 sheets under high temperature/high humidity (H/H = 32.5 °C/80 %RH) conditions. Further,
Developer No. 1 was also charged in a commercially available analog copying machine
("NP-9800", available from Canon K.K.) and subjected to image formation of 2x10
5 sheets under the normal temperature/low humidity (N/L) conditions and further 1x10
5 sheets under the high temperature/ high humidity (H/H) conditions. The results of
the image formation tests are shown in Tables 3 and 4.
[0166] In Tables 3 and 4, the evaluation results are indicated by symbols respectively indicating
the following performances.
- ⓞ:
- Very good
- o:
- Good
- oΔ:
- Practically of no problem
- Δ:
- Slightly problematic
- x:
- Practically unacceptable
[0167] Further, a commercially available laser beam printer ("LBP-SX", available from Canon
K.K.) was remodeled as shown in Figure 1 (schematic view). More specifically, the
process cartridge 2 was equipped with a urethane rubber-made elastic blade 8 and a
charging roller 9. Further, the main body was equipped with a charging roller 4 and
the heat-fixing apparatus was remodeled into an apparatus 35 shown in Figure 1, Figure
2 (exploded perspective view) and Figure 3 (sectional view). Image formation was performed
by using Developer No. 1 under the following conditions.
[0168] An OPC photosensitive member 3 was primarily charged at a potential of -600 volts
and exposed to form an electrostatic latent image thereon having a light part potential
V
L of -150 volts. At the developing station, the photosensitive drum 3 and the developing
sleeve 6 (enclosing a magnet 15) were disposed with a gap of 300 µm so that the developer
layer on the sleeve 6 did not contact the photosensitive member 3, and an AC bias
(f = 1800 Hz, Vpp = 1500 V and a DC bias (V
D = -400 V) were applied in superposition from a bias application means 12 to the developing
sleeve 6, thereby developing the electrostatic latent image by a reversal development
scheme to form a toner image on the OPC photosensitive member 3. The thus-formed toner
image was transferred onto plain paper by applying a positive transfer potential and
the plain paper carrying the toner image was applied through the heat fixing apparatus
35 to fix the toner image onto the plain paper. In the heat-fixing apparatus, the
surface temperature detected by a sensor element 21d of a heating member 21 was set
to 130 °C, and a total pressure of 6 kg was applied between the heating member 21
and a pressing roller 23 with a nip of 3 mm between the pressing roller 23 and a fixing
film 22. The fixing film 22 comprised a 50 µm-thick heat-resistant polyimide film
coated, on its side contacting the transfer material P, with a low-resistivity release
layer comprising polytetrafluoroethylene with an electroconductive substance dispersed
therein.
[0169] Under the above set conditions, an image formation test (a printing test) was performed
continuously for 7000 A4-sheets at a rate of 8 A4-sheets/min. while replenishing the
developer as required under normal temperature/normal humidity (N/N = 25 °C/60 %RH)
conditions.
[0170] Similar image formation tests were performed under high temperature/high humidity
(H/H = 32.5 °C/90 %RH) conditions and low temperature/low humidity (L/L = 10 °C/15
%RH) conditions. In the high temperature - high humidity environment, after a 6500
sheets image formation test, the apparatus and developer were left standing for 5
days in the same environment and then further subjected to a 500 sheet image formation
test.
[0171] The results are shown in Tables 5 and 6.
Examples 2 - 21 and Comparative Examples 1 - 4
[0172] Toners having particle size distributions respectively shown in Table 1 were prepared
in the same manner as in Example 1 except that prescriptions also shown in Table 1
were used. (In Table 1, values x, y and z are average values.) The localization factors
of the metal complex compounds (inclusive of azo-type iron complex compound used in
Examples) for the respective toners are shown in Table 2. From these toners, Developers
Nos. 2 - 21 and Comparative Developers Nos. 1 - 4 were prepared in the same manner
as in Example 1.
[0173] The resultant developers were respectively evaluated by the same image formation
as in Example 1. The results are summarized in Tables 3 - 6.
[0174] The evaluation items listed in Tables 3 - 6 are supplemented hereinbelow.
<Evaluation by Digital copier GP-55 and Analog copier NP-9800 (Tables 3 and 4)>
[0175] The image resolution was evaluated as follows. An original image was prepared so
as to comprise 12 types of resolution images including different number of thin lines
per mm, i.e., 2.8, 3.2, 3.6, 4.0, 4.5, 5.0, 5.6, 6.3, 7.1, 8.0, 9.0 and 10.0 lines/mm,
respectively, each type including 5 thin lines spaced regularly so as to have a line
width and a spacing which were equal to each other. A copy image was prepared by reproducing
the original image under the respective image forming conditions and observed through
a magnifying glass, whereby the largest number of lines/mm at which the adjacent lines
could be observed clearly separately was taken as a resolution.
[0176] Higher number means a higher resolution.
<Evaluation by Laser beam printer LBP-SX (Tables 5 and 6)>
[0177] The evaluation was performed in the following manners for the respective items.
(1) Image density
[0178] The density of an image formed on an ordinary plain paper for copying machine (75
g/m
2) after printing 7000 sheets was evaluated by a MacBeth Reflection Densitometer (available
from MacBeth Co.) as a relative density against a density of 0.00 allotted to a printed
white background portion.
(2) Fog
[0179] Image fog (%) was evaluated as a difference between the whiteness of a white background
portion of a printed image and the whiteness of an original transfer paper by measurement
with "Reflectometer" (available from Tokyo Denshoku K.K.). A fog value exceeding 4
% is practically problematic.
(3) Image quality
[0180] A checker pattern shown in Figure 4 was printed out and the dot reproducibility was
evaluated by counting the number of lacked dots. The results were evaluated according
to the following standards:
ⓞ (very good): lack of 2 dots or less/100 dots
o (good): lack of 3 - 5 dots/100 dots
△ (fair): lack of 6 - 10 dots/100 dots
x (poor): lack of 11 dots or more/100 dots
(4) Fixability
[0181] A fixed image was rubbed with a soft tissue paper under a load of 50 g/cm
2, and the fixability was evaluated by a lowering (%) in image density after the rubbing.
The results were evaluated according to the following standards.
ⓞ (excellent): 5 % or below
o (good): at least 5 % and below 10 %
△ (fair): at least 10 % and below 20 %
x (poor): at least 20 %
(5) Anti-offset characteristic
[0182] A sample image having an image percentage of about 5 % was printed out, and the anti-offset
characteristic was evaluated by the degree of soiling on the image after printing
of 3000 sheets. The results were evaluated by the following standards.
ⓞ: Very good (non-observable)
o: Good (substantially non-observable)
Δ: Fair
x: Poor
(6) Sleeve soiling
[0183] After the printing test, the state of residual toner sticking onto the developing
sleeve surface and the influence thereof on the printed images were evaluated by observation
with eyes. The results were evaluated according to the following standards.
ⓞ: Very good (not observable)
o: Good (substantially non-observable)
Δ: Fair (sticking was observed but did not affect the images)
x: Poor (much sticking was observed and resultant in image irregularity)
(7) Film soiling
1. Toner für die Entwicklung elektrostatischer Bilder mit
(a) einem Bindemittelharz,
(b) einer langkettigen Alkylverbindung, die durch die folgende Formel (1), (2) oder
(3) wiedergegeben wird:
worin x einen Mittelwert im Bereich von 35 bis 150 bezeichnet,
worin x einen Mittelwert im Bereich von 35 bis 150 bezeichnet; z einen Mittelwert
im Bereich von 1 bis 5 bezeichnet und R H oder eine Alkylgruppe mit 1 bis 10 Kohlenstoffatomen
bezeichnet,
worin y einen Mittelwert im Bereich von 35 bis 150 bezeichnet; und
(c) einer Eisenkomplexverbindung vom Azotyp, die durch die folgende Formel (4) wiedergegeben
wird:
worin X
1 und X
2 unabhängig Wasserstoffatom, niedere Alkylgruppe, niedere Alkoxygruppe, Nitrogruppe
oder Halogenatom bezeichnen; m und m' eine ganze Zahl von 1 bis 3 bezeichnen; R
1 und R
3 unabhängig Wasserstoffatom, C
1-18-Alkyl oder -Alkenyl, Sulfonamid, Mesyl, Sulfonsäuregruppe, Carbonsäureestergruppe,
Hydroxy, C
1-18-Alkoxy, Acetylamino, Benzoylamino oder Halogenatom bezeichnen; n und n' eine ganze
Zahl von 1 bis 3 bezeichnen; R
2 und R
4 Wasserstoffatom oder Nitrogruppe bezeichnen und A
⊕ ein Kation bezeichnet, das 75 bis 98 Mol% Ammoniumion und ein anderes Ion, das aus
der Gruppe ausgewählt ist, die aus Wasserstoffion und Alkaliionen und Mischungen davon
besteht, einschließt, wobei sich durch Dazurechnen der Menge des erwähnten anderen
Ions oder der erwähnten Ionenmischung eine gesamte Kationenmenge von 100 Mol% ergibt.
2. Toner nach Anspruch 1, bei dem die erwähnte langkettige Alkylverbindung einen langkettigen
Alkylalkohol umfaßt, der durch die Formel (1) wiedergegeben wird.
3. Toner nach Anspruch 1, bei dem die erwähnte langkettige Alkylverbindung einen Alkoxyalkohol
mit langkettiger Alkylgruppe umfaßt, der durch die Formel (2) wiedergegeben wird.
4. Toner nach Anspruch 1, bei dem die erwähnte Eisenkomplexverbindung vom Azotyp eine
Löslichkeit in Methanol von 0,1 bis 8 g/100 ml hat.
5. Toner nach Anspruch 4, bei dem die erwähnte Eisenkomplexverbindung vom Azotyp eine
Löslichkeit in Methanol von 0,3 bis 4 g/100 ml hat.
6. Toner nach Anspruch 5, bei dem die erwähnte Eisenkomplexverbindung vom Azotyp eine
Löslichkeit in Methanol von 0,4 bis 2 g/100 ml hat.
7. Toner nach Anspruch 1, bei dem die erwähnte langkettige Alkylverbindung eine anzahlgemittelte
Molmasse Mn von 200 bis 2500, eine massegemittelte Molmasse Mw von 400 bis 5000 und
ein Verhältnis Mw/Mn von höchstens 3 hat.
8. Toner nach Anspruch 2, bei dem die erwähnte langkettige Alkylverbindung eine OH-Zahl
von 2 bis 150 mg KOH/g hat.
9. Toner nach Anspruch 8, bei dem die erwähnte langkettige Alkylverbindung eine OH-Zahl
von 10 bis 120 mg KOH/g hat.
10. Toner nach Anspruch 1, bei dem die erwähnte langkettige Alkylverbindung eine Säurezahl
von 2 bis 150 mg KOH/g hat.
11. Toner nach Anspruch 10, bei dem die erwähnte langkettige Alkylverbindung eine Säurezahl
von 5 bis 120 mg KOH/g hat.
12. Toner nach Anspruch 1, wobei der erwähnte Toner eine massegemittelte Teilchengröße
von 4,0 bis 10 µm hat und Tonerteilchen von 5 µm oder weniger in einem auf die Anzahl
bezogenen prozentualen Anteil (N %) und in einem auf das Volumen bezogenen prozentualen
Anteil (V %) enthält, die N/V = -0,05·N + k erfüllen, worin k eine Zahl von 3 bis
12 ist.
13. Toner nach Anspruch 12, wobei der erwähnte Toner eine massegemittelte Teilchengröße
von 4,5 bis 9 µm hat und Tonerteilchen von 5 µm oder weniger in einem auf die Anzahl
bezogenen prozentualen Anteil (N %) und in einem auf das Volumen bezogenen prozentualen
Anteil (V %) enthält, die N/V = -0,05·N + k erfüllen, worin k eine Zahl von 4 bis
10 ist.
14. Toner nach Anspruch 1, der negative triboelektrische Aufladbarkeit zeigt.
15. Bilderzeugungsverfahren mit
einem Aufladeschritt, bei dem eine Aufladeeinrichtung (11), die mit einem aufzuladenden
Element (3) in Kontakt ist, mit einer Spannung versorgt wird, um das aufzuladende
Element (3) aufzuladen,
einem Schritt der Erzeugung eines elektrostatischen Bildes auf dem aufzuladenden Element
(3), das aufgeladen ist,
einem Entwicklungsschritt, bei dem das elektrostatische Bild mit einem Toner entwickelt
wird, um auf dem aufzuladenden Element (3) ein Tonerbild zu erzeugen,
einem Übertragungsschritt, bei dem das Tonerbild direkt oder über ein Zwischenübertragungselement
auf ein Übertragungs-Bildempfangsmaterial übertragen wird, und
einem Fixierschritt, bei dem das Tonerbild auf dem Übertragungs-Bildempfangsmaterial
fixiert wird,
wobei der erwähnte Toner wie in einem der Ansprüche 1 bis 14 definiert ist.
16. Bilderzeugungsverfahren nach Anspruch 15, bei dem die erwähnte Aufladeeinrichtung
(11) eine Aufladewalzeneinrichtung umfaßt, die mit einer Spannung versorgt wird.
17. Bilderzeugungsverfahren nach Anspruch 15, bei dem die erwähnte Aufladeeinrichtung
(11) eine Aufladebürsteneinrichtung umfaßt, die mit einer Spannung versorgt wird.
18. Bilderzeugungsverfahren nach Anspruch 15, bei dem die erwähnte Aufladeeinrichtung
(11) eine Aufladerakeleinrichtung umfaßt, die mit einer Spannung versorgt wird.
19. Bilderzeugungsverfahren nach Anspruch 15, bei dem das Tonerbild, das sich auf dem
aufzuladenden Element (3) befindet, durch eine Übertragungswalzeneinrichtung (4),
die mit einer Spannung versorgt wird, auf das Übertragungs-Bildempfangsmaterial übertragen
wird.
20. Bilderzeugungsverfahren nach Anspruch 15, bei dem das Tonerbild, das sich auf dem
aufzuladenden Element (3) befindet, durch eine Übertragungsbandeinrichtung, die mit
einer Spannung versorgt wird, auf das Übertragungs-Bildempfangsmaterial übertragen
wird.
21. Bilderzeugungsverfahren nach Anspruch 15, bei dem das Tonerbild, das sich auf dem
aufzuladenden Element (3) befindet, auf das Zwischenübertragungselement übertragen
wird und das Tonerbild, das sich auf dem Zwischenübertragungselement befindet, durch
eine Übertragungswalzeneinrichtung (4), die mit einer Spannung versorgt wird, auf
das Übertragungs-Bildempfangsmaterial übertragen wird.
22. Bilderzeugungsverfahren nach Anspruch 15, bei dem das Tonerbild, das sich auf dem
aufzuladenden Element befindet, auf das Zwischenübertragungselement übertragen wird
und das Tonerbild, das sich auf dem Zwischenübertragungselement befindet, durch eine
Übertragungsbandeinrichtung, die mit einer Spannung versorgt wird, auf das Übertragungs-Bildempfangsmaterial
übertragen wird.
23. Betriebskassette, die mindestens eine Entwicklungseinrichtung (1) und ein lichtempfindliches
Element (3) umfaßt,
wobei die Entwicklungseinrichtung (1) und das lichtempfindliche Element (3) zu einer
Kassette zusammengefaßt sind, die am Hauptkörper eines Bilderzeugungsgeräts abnehmbar
angebracht werden kann,
wobei die Entwicklungseinrichtung (1) einen Toner enthält, wie er in einem der Ansprüche
1 bis 14 definiert ist.
24. Betriebskassette nach Anspruch 23, bei der das erwähnte lichtempfindliche Element
(3) eine lichtempfindliche Trommel umfaßt.
25. Betriebskassette nach Anspruch 23, bei der eine Kontaktaufladeeinrichtung (11) in
Kontakt mit der lichtempfindlichen Trommel angeordnet ist.
26. Betriebskassette nach Anspruch 25, bei der die Kontaktaufladeeinrichtung (11) eine
Aufladewalze umfaßt.
27. Betriebskassette nach Anspruch 25, bei der die Kontaktaufladeeinrichtung (11) eine
Aufladebürste umfaßt.
28. Betriebskassette nach Anspruch 25, bei der die Kontaktaufladeeinrichtung (11) eine
Aufladerakel umfaßt.
29. Betriebskassette nach Anspruch 23, bei der eine Reinigungseinrichtung (7) in Kontakt
mit dem lichtempfindlichen Element angeordnet ist.
30. Betriebskassette nach Anspruch 29, bei der die erwähnte Reinigungseinrichtung (7)
eine Reinigungsrakel umfaßt.
1. Toner pour le développement d'images électrostatiques, comprenant :
(a) une résine servant de liant,
(b) un composé alkylique à chaîne longue représenté par la formule (1), (2) ou (3)
suivante :
dans laquelle x a une valeur moyenne de 35 à 150,
dans laquelle x a une valeur moyenne de 35 à 150 ; z a une valeur moyenne de 1 à
5 et R représente H ou un groupe alkyle ayant 1 à 10 atomes de carbone,
dans laquelle y a une valeur moyenne de 35 à 150 ; et
(c) un complexe de fer de type azoïque représenté par la formule (4) suivante :
dans laquelle X
1 et X
2 représentent indépendamment un atome d'hydrogène, un groupe alkyle inférieur, un
groupe alkoxy inférieur, un groupe nitro ou un atome d'halogène ; m et m' représentent
un nombre entier de 1 à 3 ; R
1 et R
3 représentent indépendamment un atome d'hydrogène, un groupe alkyle ou alcényle en
C
1 à C
18, un groupe sulfonamide, un groupe mésyle, un groupe acide sulfonique, un groupe ester
carboxylique, un groupe hydroxy, un groupe alkoxy en C
1 à C
18, un groupe acétylamino, un groupe benzoylamino ou un atome d'halogène ; n et n' représentent
un nombre entier de 1 à 3 ; R
2 et R
4 représentent un atome d'hydrogène ou un groupe nitro ; et A
+ représente un cation comprenant 75 à 98 moles % d'ion ammonium et un autre ion choisi
dans le groupe consistant en ion hydrogène et des ions de métaux alcalins ainsi que
leurs mélanges, la quantité de cet autre ion ou de ce mélange d'ions étant ajoutée
jusqu'à ce qu'on atteigne 100 moles % de la quantité totale de cations.
2. Toner suivant la revendication 1, dans lequel le composé alkylique à chaîne longue
comprend un alcool alkylique à chaîne longue représenté par la formule (1).
3. Toner suivant la revendication 1, dans lequel le composé alkylique à chaîne longue
comprend un alkoxyalcool alkylique à chaîne longue représenté par la formule (2).
4. Toner suivant la revendication 1, dans lequel le complexe de fer de type azoïque a
une solubilité dans le méthanol de 0,1 à 8 g/100 ml.
5. Toner suivant la revendication 4, dans lequel le complexe de fer de type azoïque a
une solubilité dans le méthanol de 0,3 à 4 g/100 ml.
6. Toner suivant la revendication 5, dans lequel le complexe de fer de type azoïque a
une solubilité dans le méthanol de 0,4 à 2 g/100 ml.
7. Toner suivant la revendication 1, dans lequel le composé alkylique à chaîne longue
a une moyenne numérique du poids moléculaire Mn de 200 à 2500, une moyenne pondérale
du poids moléculaire Mw de 400 à 5000 et un rapport Mw/Mn d'au plus 3.
8. Toner suivant la revendication 2, dans lequel le composé alkylique à chaîne longue
a un indice de OH de 2 à 150 mg de KOH/g.
9. Toner suivant la revendication 8, dans lequel le composé alkylique à chaîne longue
a un indice de OH de 10 à 120 mg de KOH/g.
10. Toner suivant la revendication 1, dans lequel le composé alkylique à chaîne longue
a un indice d'acide de 2 à 150 mg de KOH/g.
11. Toner suivant la revendication 10, dans lequel le composé alkylique à chaîne longue
a un indice d'acide de 5 à 120 mg de KOH/g.
12. Toner suivant la revendication 1, qui a une moyenne pondérale du diamètre de particules
de 4,0 à 10 µm et qui contient des particules de toner de 5 ou moins de 5 µm en termes
de pourcentage en nombre (N %) et de pourcentage en volume (V %) satisfaisant la relation
N/V = -0,05N + k, dans laquelle k représente un nombre de 3 à 12.
13. Toner suivant la revendication 12, qui a une moyenne pondérale du diamètre de particules
de 4,5 à 9 µm et qui contient des particules de toner de 5 ou moins de 5 µm en termes
de pourcentage en nombre (N %) et de pourcentage en volume (V %) satisfaisant la relation
N/V = -0,05N + k, dans laquelle k représente un nombre de 4 à 10.
14. Toner suivant la revendication 1, présentant une capacité de chargement triboélectrique
négatif.
15. Procédé de formation d'images, comprenant :
une étape de chargement consistant à fournir une tension à un moyen de chargement
(11) en contact avec un élément (3) à charger pour charger cet élément (3),
une étape de formation d'une image électrostatique sur l'élément (3) chargé,
une étape de développement consistant à développer l'image électrostatique avec un
toner pour former une image de toner sur l'élément (3) chargé,
une étape de transfert consistant à transférer l'image du toner à une matière réceptrice
de transfert directement par, ou en passant par, un élément de transfert intermédiaire,
et
une étape de fixage consistant à fixer l'image de toner sur la matière réceptrice
de transfert,
dans lequel ledit toner répond à la définition suivant l'une quelconque des revendications
1 à 14.
16. Procédé de formation d'images suivant la revendication 15, dans lequel le moyen de
chargement (11) comprend un moyen muni d'un rouleau de chargement alimenté avec une
tension.
17. Procédé de formation d'images suivant la revendication 15, dans lequel le moyen de
chargement (11) comprend un moyen muni d'une brosse de chargement, alimenté avec une
tension.
18. Procédé de formation d'images suivant la revendication 15, dans lequel le moyen de
chargement (11) comprend un moyen muni d'une lame de chargement, alimenté avec une
tension.
19. Procédé de formation d'images suivant la revendication 15, dans lequel l'image de
toner sur l'élément (3) à charger est transférée à la matière réceptrice de transfert
par un moyen muni d'un rouleau de transfert (4) alimenté avec une tension.
20. Procédé de formation d'images suivant la revendication 15, dans lequel l'image de
toner sur l'élément (3) à charger est transférée à la matière réceptrice de transfert
par un moyen muni d'une courroie de transfert, alimenté avec une tension.
21. Procédé de formation d'images suivant la revendication 15, dans lequel l'image de
toner sur l'élément (3) à charger est transférée à l'élément de transfert intermédiaire,
et l'image de toner sur l'élément de transfert intermédiaire est transférée à la matière
réceptrice de transfert par un moyen muni d'un rouleau de transfert (4) alimenté avec
une tension.
22. Procédé de formation d'images suivant la revendication 15, dans lequel l'image de
toner sur l'élément à charger est transférée à l'élément de transfert intermédiaire,
et l'image de toner sur l'élément de transfert intermédiaire est transférée à la matière
réceptrice de transfert par un moyen muni d'une courroie de transfert, alimenté avec
une tension.
23. Cartouche de traitement, comprenant au moins un moyen de développement (1) et un élément
photosensible (3),
le moyen de développement (1) et l'élément photosensible (3) étant intégrés à une
cartouche qui peut être montée de manière amovible sur un corps principal d'un appareil
de formation d'images,
dans laquelle le moyen de développement (1) contient un toner répondant à la définition
suivant l'une quelconque des revendications 1 à 14.
24. Cartouche de traitement suivant la revendication 23, dans laquelle l'élément photosensible
(3) comprend un tambour photosensible.
25. Cartouche de traitement suivant la revendication 23, dans laquelle un moyen de chargement
par contact (11) est placé en contact avec le tambour photosensible.
26. Cartouche de traitement suivant la revendication 25, dans laquelle le moyen de chargement
par contact (11) comprend un rouleau de chargement.
27. Cartouche de traitement suivant la revendication 25, dans laquelle le moyen de chargement
par contact (11) comprend une brosse de chargement.
28. Cartouche de traitement suivant la revendication 25, dans laquelle le moyen de chargement
par contact (11) comprend une lame de chargement.
29. Cartouche de traitement suivant la revendication 23, dans laquelle un moyen de nettoyage
(7) est placé en contact avec l'élément photosensible.
30. Cartouche de traitement suivant la revendication 29, dans laquelle le moyen de nettoyage
(7) comprend une lame de nettoyage.