Note: Descriptions are shown in the official language in which they were submitted.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
- 1 -
DESCRIPTION
TONER FOR ELECTROSTATICALLY CHARGED IMAGE DEVELOPMENT
FIELD OF THE INVENTION
The present invention relates to a toner for
developing an electrostatically charged image in pressure
fixing type and heat roller fixing type (also referred to
hereinafter as "pressure heating type" or "pressure heating
system").
More specifically, this invention relates to a
practically applicable toner type developing agent of the
dry one-component magnetic type, dry one-component
nonmagnetic type, dry two-component type, liquid dried type,
or liquid type that can be pressure fixed onto film or other
substrates to be copied, has adequate fixing properties
(hereinafter referred to as "fixing ability"), toner spent
properties, and transparency to enable pressure fixing at a
low temperature of less than 100°C even in the case of heat
roller fixing, can form sharp images, and is excellent in
high-speed fixing ability and preservation stability,
thereby enabling to secure an adequate temperature range in
which offset phenomena will not occur (hereinafter referred
to as "offset-free temperature range").
This invention also concerns the above-mentioned
toner that can be applied widely in copiers, printers,
facsimile machines, color copiers, color laser copiers,
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
- 2 -
color laser printers, and high speed electrophotographic
printers.
BACKGROUND ART
With recent rapid spread of office automation,
there have been growing demands, in electrostatically
charged image developing copiers and printers, for higher
resistance to mechanical impact for accommodating to high-
speed printing and demands for high grade images, in other
words, sharpness, low-temperature fixing ability and
excellent light transmittance for accommodating to color
toners.
Such needs for high speed copying and high grade
images require to secure the necessary and adequate toner
particle strength and a wide offset-free temperature range
that enables practical applications at low temperatures.
Furthermore, it is expected to realize the oil-free type
copying methods, which do not require oil feeding to the
fixing roll and thus bring no problem of soiling the
substrates to be copied.
Under these circumstances, the present inventor
found and discloses in JP-A-2000-66438 that a toner for
developing a heat roller fixing type electrostatically
charged image comprising a polyolefin resin having a cyclic
structure as the binder resin and adopting a suitable
combination of fatty acid amide wax, oxidized polyethylene
wax, polyethylene wax and acid-modified polypropylene wax so
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
- 3 -
as to impart various functions,. can answer the above
demands.
This toner, however, has limits in terms of the
copying speed and fixing temperature in heat roller fixing
applications. Meanwhile, the market has recently been
demanding even higher copying speeds and adequate
accommodations for demands for low-temperature fixing due to
the need of saving electric power.
In forming full color images with three or four
colors (Y: yellow, M: magenta, C: cyan, B: blue) added and
mixed by the electrophotographic method, the process of
transfer onto the substrate to be copied needs a toner
particle which is infinitely close to sphere or true sphere
and has smooth surface conditions.
However, the conventional mechanical milling
method and. air impact milling method using a high-velocity
air flow could hardly be successful in preparing toners that
were spherical and had smooth surfaces.
In heat roller fixing systems which are currently
and generally used for fixing a full-color image onto paper,
OHP film, or other substrates to be copied, an excessive
amount of heat must be supplied to fix a three- or four-
color toner, and silicone oil or the like should also be
supplied to the fixing roller to prevent transfer of toner
onto the heat roller (so-called "offset phenomenon").
Performances required of a toner are diverse and
include charging properties, fixing ability, wear
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
- 4 -
resistance, conveyability, preservation stability (the
tendency of toner particles not to agglomerate mutually and
form lumps even after a long period of time), etc. However,
a toner obtained by dry mixing in a conventional compounding
method is not satisfactory in meeting all such needs.
In order to answer each of the above needs, a
toner must be provided with various conflicting functions.
In order to solve such problems, microcapsule toners having
a structure in which a core material (core substance)
particle called "core" is encapsulated with a shell material
(shell substance) called "shell" have been being proposed.
For example, a binder resin which has a good fixing ability,
but tends to give rise to the offset phenomenon due to poor
preservation stability may be used as the core material, and
a coating resin which has good preservation stability and
offset-free property may be used as the shell material,
thereby satisfying the conflicting demands.
Ideas have been proposed concerning such function-
separated type microcapsule toners. For example, JP-A-9
292735 discloses a film fixing heating type image forming
device that uses a microcapsule toner prepared by a
suspension polymerization method. JP-A-59-53856 and JP-A-
59-61842 disclose examples prepared by the similar method.
Also, JP-B-56-13945 proposes a preparation method
based on the spray drying method; JP-B-8-16793 proposes a
preparation method based on the water-drop phase separation
method; and JP-A-3-56970 proposes a preparation method in
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
- 5 -
which the shell layer is formed by an in situ polymerization
method and to get microparticles using a high-pressure
homogenizer.
Besides the above, interfacial polymerization
methods, coacervation methods, dry capsule methods, etc.
have also been introduced.
However, these prior art techniques, except for
the spray drying method, use water as a medium, thus
rendering the drying process troublesome. Therefore, they
were inadequate for.producing microcapsule toners at an
industrial scale.
Also, the spray drying method had a difficulty~in
obtaining uniform particulates of the desired average
particle diameter, usually of 10 ~,m or less.
DISCLOSURE OF THE INVENTION
An object of the present invention is to provide a
microcapsule toner which can be adequately used in a low-
temperature heat fixing system o.r in a pressure fixing
system that enables high speed copying, as well as in a heat
roller fixing system, solves the problems of prior-art
microcapsules, and yet is excellent in preservation
stability and prevention of the offset phenomenon.
The present inventor has completed this invention
upon finding that the above-described problems can be solved
by using two types of olefin copolymers, each having a
cyclic structure but differing in glass transition
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
- 6 -
temperature and number average molecular weight, one being
used as a binder resin for the core and the other as a resin
in the shell for coating the core (coating resin), of a
microcapsule toner particle.
More specifically, this invention provides a toner
for developing an electrostatically charged image which
comprises a microcapsule toner particle composed of a core
and a shell, the core comprising a colorant and a binder
resin containing an olefin copolymer having a cyclic
structure, said olefin copolymer having a glass transition
temperature ranging from -20°C to less than 60°C and a
number average molecular weight ranging from 100 to 20,000,
and the shell comprising a resin for coating the core.
The invention also provides a toner for developing
an electrostatically charged image which comprises a
microcapsule toner particle composed of a core comprising a
colorant and a binder resin; and a shell comprising a resin
for coating the core containing an olefin copolymer having a
cyclic structure, said olefin copolymer having a glass
transition temperature ranging from 60°C to 180°C and a
number average molecular weight ranging from 1,000 to
100,000.
The invention furthermore provides a toner for
developing an electrostatically charged image which
comprises a microcapsule toner particle composed of a core
and a shell, the core comprising a colorant and a binder
resin containing an olefin copolymer having a cyclic
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
structure, said olefin copolymer having a glass transition
temperature ranging from -20°C to less than 60°C and a
number average molecular weight ranging from 100 to 20,000,
and the shell comprising a resin for coating the core
containing an olefin copolymer having a cyclic structure,
said olefin copolymer having a glass transition temperature
range from 60°C to 180°C and a number average molecular
weight ranging from 1,000 to 100,000.
The present invention shall now be described more
in detail.
(A] Materials composing the core of the microcapsule
tonerparticle
The core comprises a binder resin and a colorant
as the essential components. It optionally contains
additives such as a function imparting agent, a charge
controlling agent and other additives.
(1) Binder resins
The below-mentioned binder resins for heat fixing
and for pressure fixing or olefin copolymers having a cyclic
structure are used as a binder resin which constitutes,
along with a colorant, the core of the microcapsule toner.
These resins have a lower melting point or softening point
and a higher fixing ability in comparison to the below-
mentioned coating resins which constitute the shell.
Examples of binder resins for heat fixing include
styrene polymers such as polystyrene, substituted
polystyrene, etc.; styrene copolymers such as styrene-
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
- $ _
acrylic ester copolymer, styrene-methacrylic ester
copolymer, styrene-acrylonitrile copolymer, etc.; acrylic
acid resins such as poly(meth)acrylic acid resin,
poly(meth)acrylic ester resin, etc.; polyester resins; and
epoxy resins. These resins can be used alone or in
combination of two or more.
Examples of binder resins for pressure fixing
include vegetable, animal, mineral, and petroleum waxes such
as carnauba wax, candelilla wax, lanolin, beeswax, montan
wax, paraffin wax, microcrystalline wax, etc.; higher fatty
acid derivatives such as polyvalent alcohol esters, e.g.,
with stearic acid, palmitic acid, oleic acid, lauric acid,
etc., and metal salts of higher fatty acids, e.g., calcium
stearate, zinc stearate, lead stearate, magnesium stearate,
etc.; polyolefin waxes such as polyethylene wax,
polypropylene wax, etc.; olefinic homopolymers and
copolymers such as ethylene-(meth)acrylic acid copolymer,
ethylene-(meth)acrylic ester copolymer, ethylene-vinyl
acetate copolymer, ionomer resin, etc.; styrene resins such
2Q as low molecular weight polystyrene, styrene-butadiene
copolymer, styrene-acrylonitrile copolymer, etc.; epoxy
resins, and polyester resins. These resins can be used
alone or in combination of two or more.
Employing a low-temperature fixing system to
enable high-speed copying and obtain a sharp, high-grade
image requires a reliable fixing ability that can
accommodate for a pressure heat fixing (heat pressure
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
_ g _
fixing) system. Therefore, the types and compositions of
the binder resins suitable for the fixing methods should be
selected.
In order to provide a high offset-free property by
broadening the offset-free temperature range in which the
offset phenomenon will not occur, it is preferable to use
the below-described olefin copolymer having a cyclic
structure (hereinafter Cyclic Olefin Copolymer; also
abbreviated as COC) as the binder resin of the core
material, in place of the above-mentioned binder resins for
heat fixing and pressure fixing.
In order to provide the cyclic olefin copolymer
used as the core with a more advanced fixing ability than
that of the shell, the olefin copolymer is required to have
a glass transition temperature (Tg) ranging from -20°C to
less than 60°C and a number average molecular weight (Mn)
ranging from 100 to 20,000. Tg of less than -20°C will
cause high viscoelasticity and render the printed image
sticky, while Tg of 60°C or higher will provide an
insufficient fixing property due to excess rigidity. Also,
Mn of less than 100 will not provide a sufficient fixation,
while Mn exceeding 20,000 will make a resin hardly soluble
in a solvent, thus being improper for practical use.
Here, the glass transition temperature (Tg) refers
to the temperature at the middle point of the displacement
showing the heat of transition as measured by the
differential scanning calorimetry method (DSC). The number
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-10-
average molecular weight (Mn) is the value measured by gel
permeation chromatography (GPC) and based on calibration by
standard polyethylene or polystyrene. More specifically,
the number average molecular weight is the value obtained by
measuring under the following conditions.
[Conditions]
Column used: JORDI-SAEULE 500 x 10 LINEAR
Mobile phase: 1,2-dichlorobenzene (135°C),
flow rate: 0.5 ml/min
Detector: Differential refractometer
The cyclic olefin copolymer (COC) shall now be
described in detail below.
The cyclic olefin copolymer (COC) is a copolymer
of a lower alkene with 2 to 12 carbons, preferably 2 to 6
carbons, such as an a-olefin (or more broadly, non-cyclic
olefins), e.g., ethylene, propylene, butylene, etc., and a
cyclic andlor polycyclic compound (cyclic (cyclo) olefin)
with 3 to 17 carbons, preferably 5 to 22 carbons having at
least one double bond, such as norbornene,
tetracyclododecene, dicyclopentadiene, cyclohexene, etc.,
preferably norbornene or tetracyclododecene. Such a
copolymer is colorless and transparent and has a high light
transmittance.
The COC is prepared by polymerization methods
using a metallocene catalyst system, a Ziegler catalyst
system, a catalyst for metathesis polymerization, that is, a
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
- 11 -
catalyst for a double bond opening and a ring opening
polymerization reaction.
Synthesis examples of olefin copolymers with the
above structure are disclosed in JP-A-5-339327, JP-A-5-9223,
JP-A-6-271628, EP-A-203799, EP-A-407870, EP-A-283164, EP-A-
156464, and JP-A-7-253315.
According to the above literatures, the cyclic
olefin copolymer can be prepared by copolymerizing one or
more types of monomers of the above, optionally with one
type of the above non-monomer, in the presence of
aluminoxane or other cocatalysts, and at least one type of
metallocene catalyst comprising for example zirconium or
hafnium, at a temperature of -78 to 150°C, preferably 20 to
80°C and at a pressure of 0.01 to 64 bars. EP-A-317262
describes other useful polymers. A hydrogenated polymer or
a copolymer of styrene and dicyclopentadiene may also be
used.
A metallocene catalyst is activated when dissolved
in an inert hydrocarbon, such as an aliphatic or aromatic
hydrocarbon. For example, a metallocene catalyst is
dissolved in toluene to be preactivated, whereby a reaction
is carried out in the solvent.
The important features of the cyclic olefin
copolymer reside in a softening point, a melting point,
viscosity, dielectric properties, offset-free temperature
range, and transparency. These can be adjusted by
effectively selecting a monomer/comonomer ratio, that is, a
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-12-
ratio of the monomer units in the copolymer, molecular
weight, molecular weight distribution, a hybrid polymer,
blending, and additives.
The molar ratio of the non-cyclic olefin and the
cyclic olefin charged for the reaction may be varied within
a wide range depending on the target cyclic olefin
copolymer, and is preferably adjusted to 50:1 to 1:50, and
especially preferably 20:1 to 1:20.
For example, when two components,.ethylene as a
non-cyclic olefin and norbornene as a cyclic olefin, are
used for the reaction to produce a cyclic olefin copolymer,
the glass transition temperature (Tg) of the reaction
product is largely influenced by the ratio of these
components used. When the norbornene content increases, the
Tg tends to increase as well. For example, a composition
wherein the norbonene content is 15 mole % or less (ethylene
content 85 mole % or more) can provide a copolymer whose Tg
is from -20°C to 60°C. On the other hand, a composition
wherein the norbonene content is 15 mole % or more can
provide a copolymer whose Tg is from 60°C to 180°C.
Physical properties such as the number average molecular
weight are adjusted according to the known methods in the
literatures.
The composition of the olefin copolymer having a
cyclic structure used in the present invention is as
follows.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-13-
The binder resin for the core is preferably
composed of an unmodified cyclic olefin polymer and an acid-
modified cyclic olefin polymer at a weight ratio of from
95:5 to 5:95.
The unmodified cyclic olefin polymer has a number
average molecular weight (Mn; measured as a standard
polyethylene based value by GPC, the same applies
hereinafter) of from 100 to 20,000, preferably from 1,000 to
10,000, a weight average molecular weight (Mw) of from 200
to 40,000, preferably from 6,000 to 30,000, and a glass
transition temperature (Tg) of from -20°C to less than 60°C,
preferably from 40°C to 59°C.
Meanwhile, the acid-modified cyclic olefin polymer
has a number average molecular weight (Mn) of from 100 to
20,000, preferably from 1,000 to 10,000, a weight average
molecular weight (Mw) of from 300 to 80,000, preferably from
3,000 to 40,000, and a glass transition temperature (Tg) of
from -20°C to less than 60°C, preferably from 40°C to
59°C.
In order to secure the fixing ability to be
required and broaden the offset-free temperature range for
practical use, the above cyclic olefin.copolymer preferably
comprises a low molecular weight polymer or polymer fraction
(A) of low viscosity and a high molecular weight polymer or
polymer fraction (B) of high viscosity, whose physical
properties are described below.
More specifically, the olefin copolymer of the
invention may be a mixture of polymer (A) and polymer (B);
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-14-
or may have a single-peak in a molecular weight distribution
with a polymer fraction of a number average molecular weight
of less than 7,500 and a polymer fraction of number average
molecular weight of 7,500 or more; or may have two or more
peaks in a molecular weight distribution wherein the polymer
fraction corresponding to at least one peak has a number
average molecular weight of less than 7,500 and the polymer
fraction corresponding to the other peaks has a number
average molecular weight of 7,500 or more.
The afore-mentioned composition of the olefin
copolymer serves to broaden the offset-free temperature
range at both the high and low temperature sides, thereby
improving the toner fixing ability in high-speed copying, as
well as the fixing properties at low temperatures and low
pressures.
The polymer or polymer fraction (A) (referred to
hereinafter as "component (A)") has
a number average molecular weight (as measured based on
standard polyethylene by GPC (gel permeation
chromatography), the same applied hereinafter) of less than
7,500, preferably 1000 to less than 7,500, and more
preferably 2,000 to less than 7,500;
a weight average molecular weight of less than 15,000,
preferably 1,000 to less than 15,000, and more preferably,
4,000 to less than 15,000;
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-15-
an intrinsic viscosity (i.v.; the intrinsic viscosity
at 135°C when 1.0 g of the polymer is dissolved uniformly in
100 ml of decalin) of less than 0.25 dl/g; and
a glass transition temperature (Tg) of preferably less
than 70°C.
The polymer or polymer fraction (B) (referred to
hereinafter as "component (B)") has
a number average molecular weight of 7,500 or more,
preferably 7,500 to 50,000;
a weight average molecular weight 15,000 or more,
preferably 15,000 to 500,000; and
an intrinsic viscosity (i.v.) of 0.25 dl/g or more.
Further, the content of component (B) is less than
50% by weight, preferably 5 to 35% by weight of the entire
binder resin.
Component (B) provides a toner particle with the
structural viscosity to enhance the offset preventing effect
and adhesion onto paper, film, or other substrates to be
copied. However, when the content of component (B) is 50%
by weight or more, the uniform kneading property becomes
drastically poor to damage the toner performance. In other
words, a high quality image or a sharp image with high
fixing strength and excellent heat response property becomes
difficult to form or the mechanical milling properties
become low, making it difficult to prepare a toner having
the required particle diameter.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-16-
By the way, the polymer or polymer fraction used
herein refers to polymer fractions of the cyclic olefin
copolymer; where the olefin polymer is composed of a mixture
of various components having different number average
molecular weight, etc., the polymer or polymer fraction
refers to each of the polymer components prior to mixing,
while the polymer or polymer fraction refers to the polymer
fractions obtained by separating the final synthesis product
by GPC or other suitable means. When the polymer fraction
is monodisperse or close to monodisperse, a number average
molecular weight (Mn) of 7,500 corresponds approximately to
a weight average molecular weight (Mw) of 15,000.
While the low-viscosity component (A) of the
olefin copolymer contributes to broadening the offset-free
temperature range at the low temperature side, the high
viscosity component (B) contributes to broadening of the
offset-free temperature range at the high temperature side.
Thus, a high viscosity component (B) with Mn of 20,000 or
more is desired to broaden the offset-free temperature range
more effectively at the high temperature side.
The contents of components (A) and (B) should be
0.5 or more part by weight, preferably 5 to 100 parts by
weight, respectively, based on the total amount of the
binder resin defined as 100 parts by weight. Less than 0.5
part by weight each of both the components will not provide
a broad offset-free temperature range suitable for practical
use.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-17-
The high viscosity (high molecular weight) and low
viscosity (low molecular weight) olefin copolymers having a
cyclic structure have the number average molecular weights
(Mn), weight average molecular weights (Mw), and intrinsic
viscosity (i.v.) as mentioned above, and thus have the
degree of dispersion of the molecular weight distribution
indicated by Mw/Mn as low as 1-2.5, are monodisperse or
close to monodisperse. This makes it possible to produce a
toner having a high heat response and a high fixing
strength, thereby enabling the fixing of toner at low
temperatures and low pressures. This also contributes to
preservation stability of the toner, spent toner properties,
uniformity of charge distribution, and electirical stability
by constant charge/discharge efficiency. It is especially
preferable for the low viscosity polymer or polymer fraction
to have monodispersity or substantail monodispersity,
because the toner will then have excellent, so-called heat
response properties, such as exhibition of instantaneous
melting and setting,, etc.
The olefin copolymer is also colorless,
transparent, and has a high light transmittance. Thus, the
olefin polymer can be applied adequately to color toners.
For example, it has been confirmed that excellent
transparency is obtained even when the azo pigment,
"Permanent Rubin F6B" (manufactured by Clariant Co.) is
added, followed by adequate kneading, and then sheets are
made by a press machine. Also, measurements by the DSC
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-18-
method (differential scanning calorimetry method) have shown
that the olefin copolymer has an extremely low heat of
fusion. Thus, significant reduction of the amount of energy
consumed for toner fixing can be anticipated.
Also, by introducing carboxyl groups in the olefin
copolymer, the compatibility with other resins can be
improved and the dispersion properties of the pigments in
the toner can be improved. The introduction of carboxyl
groups makes it possible to improve the adhesion of toner
onto paper, film, or other copying medium and the fixing
ability.
For introducing carboxyl groups, advantageously
employed is a two-step reaction method in which the olefin
copolymer having a cyclic structure is prepared first and
then carboXyl groups are introduced.
At least two methods may be given for introducing
carboxyl groups.
In one method, a methyl or other alkyl group at
the end of the copolymer is oxidized and converted into a
carboxyl group by the fusing air oxidation method. However,
in the case of an olefin polymer prepared by using a
metallocene catalyst, it is difficult to introduce many
carboxyl groups by this method because such a polymer has
only a few branches.
Another method is the method in which t-butanol
peroxide or other peroxide is used as an initiator to graft
polymerize malefic anhydride, acrylic acid, or methacrylic
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-19-
acid onto the olefin polymer having a cyclic structure so as
to attain a graft ratio of 1 to 5% by weight, preferably 3
to 5% by weight in terms of weight ratio with respect to the
olefin polymer.
The graft ratio of less than 1% by weight will be
insufficient to achieve the improvement in the compatibility
and the like. On the other hand, the graft ratio exceeding
5% by weight will raise intermolecular crosslinking in the
olefin polymer to increase the molecular weight. This makes
kneading and milling properties unsuitable~for practical
use. Further, a serious yellow discoloration and loss of
transparency will occur. Thus, the polymer is unsuitable
for a color toner that requires colorlessness and
transparency.
In the same manner, the compatibility with other
resins and the dispersion of the pigments in the toner can
be improved by introducing a hydroxyl group or an amino
group by a known method.
Also, a crosslinked structure can be introduced in
the olefin polymer to improve the toner fixing property.
One method of introducing a crosslinked structure
is terpolymerization of the non-cyclic olefin and the cyclic
olefin with cyclopentadiene, cyclohexadiene, norbornadiene,
tetracyclododecadiene, butadiene, or other dime monomer in
synthesizing the above-described olefin polymer.
As a result of this method, the olefin polymer has
a terminal showing an activity even without a crosslinking
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-20-
agent. A known chemical reaction such as oxidation or
epoxidation, or the addition of a crosslinking agent to form
a crosslinked structure results in the functioning of the
olefin polymer.
Another method is to add a metal such as zinc,
copper or calcium to the olefin polymer of a cyclic
structure having carboxyl groups introduced therein, and
then blend and melt the mixture with a screw to disperse the
metal as fine particles in the olefin polymer, thereby
forming an ionomer having a crosslinked structure.
Concerning a technology itself on such an ionomer, US-
4693941, for example, discloses a terpolymer of ethylene
containing carboxyl groups which may take the form of a
divalent metal salt upon partial or complete neutralization
in an attempt to ob=tain toughness.
JP-A-6-500348 reports a polyester resin molded
product containing an ionomer of an unsaturated carboxylic
acid prepared for the same purpose, in which approximately
to 80% of the carboxylic acid groups is neutralized with
20 zinc, cobalt, nickel, aluminum or copper (II).
A cyclic olefin polymer, to which an acid-modified
olefin polymer having a cyclic structure with carboxyl group
introduced has been added at 5 to 95% by weight, may be used
as the core material. This will be an effective means for
securing the fixing ability and the offset-free temperature
range.
(2) Colorants
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-21-
Carbon black, diazo yellow, phthalocyanin blue,
quinacridone, carmine 6B, monoazo red, perylene, or other
colorants used for conventional monochromatic or color
copier toners may be incorporated as the colorant in the
core material.
(3) Function imparting agents
Various types of waxes may be used as a function
imparting agent for broadening the offset-free temperature
range and improving the offset-free property. At least one
type of wax selected from polar waxes, such as amide wax,
carnauba wax, higher fatty acids and esters thereof, higher
fatty acid metal soaps, partially saponified higher fatty
acid esters, and higher fatty acid alcohols; and nonpolar
waxes, such as polyolefin waxes and paraffin wax, may be
used as a function imparting agent.
Among the various waxes, fatty acid amide waxes,
oxidized polyethylene waxes, and acid-modified polypropylene
waxes are preferable from the viewpoint of achieving a broad
offset-free temperature range.
In order to broaden the above-described offset-
free temperature range of the toner and improve the toner
performance, the wax is preferably used in the manner
described below.
That is, two or more types of waxes, which have
different melting points (the peak temperature in
differential scanning calorimetry (DSC) measurements) in the
range of 80 to 140°C, are preferably used in combination.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-22-
If the melting point is less than 80°C, blocking due to low
melting point substances will tend to occur. Meanwhile,
since a function imparting agent is required to melt
completely at the kneading temperature that exceeds the
softening point of the binder resin, the upper limit of the
wax is limited by the softening point (approximately 135 to
140°C) of the olefin polymer having a cyclic structure which
is the principal component of the binder resin and is
preferably I40°C.
More specifically, two or more types of waxes
selected from the fatty acid amide waxes and hydrocarbon
waxes given below are used.
(i) Waxes having polar groups
Waxes having polar groups include various fatty
acid amide waxes, for example, arachic acid monoamide
(melting point: 110°C), behenic acid monoamide (melting
point: 115°C), N,N'-dioleyl sebacic acid amide (melting
point: 115°C), N,N'-dioleyl adipic acid amide (melting
point: 119°C), and N,N'-distearyl isophthalic acid amide
(melting point: 129°C); oxidized olefin waxes, for example,
oxidized polyethylene wax (melting point: 116°C); acid-
modified polyolefin waxes, for example, acid-modified
polypropylene wax (melting point: 138°C); and carnauba wax
(melting point: approximately 80°C).
(ii) Nonpolar waxes (waxes without polar groups)
Nonpolar waxes include olefin waxes which are
hydrocarbon waxes, for example, polyethylene wax (melting
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-23-
point: 130°C), polypropylene wax (melting point: 120 to
150°C), paraffin wax (melting point: approximately 60 to
80°C), sazole wax (solidifying point: approximately 98°C),
and microcrystalline wax (melting point: 80 to 100°C).
A silicone oil having mold release characteristics
may be used as a function imparting agent for prevention of
the offset phenomenon, in combination with an above-
mentioned wax, as long as it does not adversely affect the
effect of the present invention.
(4) Charge control agent
Nigrosine dyes, fatty acid-modified Nigrosine
dyes, metallized Nigrosine dyes, metallized fatty acid-
modified Nigrosine dyes, chromium complexes of 3,5-di-t-
butylsalicylic acid, quaternary ammonium salts,
triphenylmethane dyes, azochromium complexes, and other
known charge control agents may be incorporated in the core
material.
(5) Other additives
In addition to the aforementioned toner
components, if desired, a flowing agent such as colloidal
silica (including fumed silica), aluminum oxide or titanium
oxide and a lubricant comprising a fatty acid metal salt
such as barium stearate, calcium stearate or barium laurate
may be incorporated in the core material, as long as they do
not adversely affect the effect of the present invention.
(6) Amount of components to be incorporated
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-24-
The amounts of the components to be incorporated
in the core material of the invention are similar to those
in the case of the toner for electrostatically charged image
developing copiers and printers, and are shown in Table 1.
Table l: General composition of toners (unit: wt.%)
BinderColorantCharge FunctionMagneticSolvent
resin controlimpartingpowder
agent agent
D two-com onent toner50-1000-20 0-10 0-20 - -
Dry nonmagnetic one-50-1000-20 0-10 0-20 -
com onent toner
Dry magnetic one-component0-100 0-20 0-10 0-20 0-60 -
toner
Dry polymerized toner50-1000-20 0-10 0-20 - -
Li uid dried toner 15-50 0-10 0-5 0-10 - 50-70
Liquid toner 15-50 0-10 0-5 0-10 - 50-70
[B] Materials constituting the shell material of the
microcapsule toner particles
The shell material comprises a coating resin as
the essential component and arbitrary additives such as a
function imparting agent, a charge control agent, or the
like. The coating resins used in the shell also have fixing
ability, thus perform as binder resins similar to the
aforementioned resins used in the core.
(1) Coating resin
A resin for fixing or an olefin polymer having a
cyclic structure described below is used as the coating
resin that constitutes the shell of the microcapsule toner
particles.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-25-
In comparison to the binder resin of the core
material, the coating resins has a higher melting point or
softening point and thus better preservation stability.
Examples of coating resins for fixing include
homopolymers and copolymers of styrene, substituted
styrenes, and derivatives thereof, (meth)acrylic acid,
(meth)acrylic esters, malefic anhydride, malefic anhydride
esters, and derivatives thereof, malefic anhydride amide,
nitrogen containing vinyl compounds, such as vinyl pyridine,
N-vinyl imidazole, etc., vinyl monomers, such as vinyl
acetal, vinyl chloride, acrylonitrile, vinyl acetate; etc.,
vinylidene monomers, such as vinylidene chloride, vinylidene
fluoride, etc., and olefin monomers, such as ethylene,
propylene, etc., condensation polymers, such as polyesters,
epoxy resins, polyearbonates, polyamides, polyurethanes,
polyureas, rosin, modified rosin, phenol resins, melamine
resins, polyphenylene oxides, and terpene resins, fatty
hydrocarbon resins, fatty cyclic hydrocarbon resins, and
petroleum resins, and such a resin may be used alone or in
combination of two or more types.
In order to prevent the offset phenomenon, in
which the toner is transferred onto the heat roller, and to
improve the preservation stability further, the olefin
polymer having a cyclic structure described below is
preferably used as the coating resin of the shell material.
An unmodified olefin having a cyclic structure is
preferable as the coating resin of the shell material.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-26-
Since the preservation stability of the toner will be
secured adequately as long as the glass transition
temperature (Tg) of the polymer used is 60°C or more, the
entire amount may be replaced by an acid-modified olefin
polymer having a cyclic structure whose Tg is 60°C or more.
Such an unmodified olefin polymer having a cyclic
structure has a number average molecular weight (Mn) ranging
from 1,000 to 100,000, preferably from 2,000 to 50,000, a
weight average molecular weight (Mw) ranging from 2,000 to
200,000, preferably from 4,000 to 100,000, and a glass
transition temperature (Tg) ranging from 60°C to 180°C,
preferably from 60°C to 80°C.
Meanwhile, the above-mentioned acid-modified
olefin polymer has a number average molecular weight (Mn)
ranging from 1,000 to 100,000, preferably from 2,000 to
50,000, a weight average molecular weight (Mw) ranging from
3,000 to 300,000, preferably from 6,000 to 200,000 and a
glass transition temperature (Tg) ranging from 60°C to
180°C, preferably from 60°C to 80°C.
If the glass transition temperature of the above-
described olefin polymer is less than 60°C, there will be
many problems in the preservation stability of the toner
particles, and when the glass transition temperature is in
the excess of 180°C, the melting point will be raised and
the fixing ability will tend to be poor. Also, when the
number average molecular weight of the above-described
olefin polymer is less than 1,000, an adequate fixing
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
_27-
strength cannot be obtained, while when the number average
molecular weight exceeds 100,000, the required solubility in
the solvent will be difficult to secure.
The modified substances, the crosslinked
substances, and the various characteristics besides the
glass transition temperature and number average molecular
weight of the above-described olefin polymer having a cyclic
structure are the same as those indicated above for the
olefin polymer having a cyclic structure used in the core
material., and descriptions thereof shall be omitted.
(2) Function imparting agents
In order to broaden the offset-free temperature
range and further improve the offset-free property of the
toner particle surface, the same function imparting agents
(wax, silicone oil) as used in the above-described core
material may also be incorporated in the shell material.
The above-described preferable forms of use, etc. also can
be applied to the function imparting agents to be
incorporated in the shell material.
(3) Charge control agents
The same charge control agents used in the above-
described core material may be incorporated in the shell
material.
(4) External additives
The surface of the shell material of the toner
particles may be coated by an external additive as
necessary.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-28-
Examples of external additives include flowing
agents, such as colloidal silica (including fumed silica),
aluminum oxide, titanium oxide, etc., and lubricants
comprising a fatty acid metal salt, such as barium stearate,
calcium stearate, barium laurate, etc., and such an external
additive may be used alone or in combination of two or more
types. It is preferable that these additives have been made
hydrophobic.
The amount of external additive used is 0.01 to
10, preferably 0.05 to 5 parts by weight per 100 parts by
weight of toner particles.
If the shell material is to be coated by an
external additive, a solution containing the external
additive is coated onto the surface of~the particles or the
external additive is adhered to the surface of the particles
by other methods.
(5) Amount of the components to be incorporated
The amounts of the above-mentioned components,
with the exception of the colorant to be incorporated, in
the shell material are as shown in Table 1 above.
[C~ Microcapsule toner particle
The microcapsule toner particle has a capsule-like
or so-called core-shell structure .i.n which the core material
is coated with the shell material.
The average particle size (diameter) of an entire
particle is preferably 3 to 10 ~,m, and the thickness of the
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-29-
outer shell ~[(outer diameter of capsule) - (diameter of
core material)] x 1/2} is preferably 0.1 to 0.5 ~,m.
According to this invention, there are the
following three modes of combination of resins for the core
material and the shell material.
(a) Core material: Olefin polymer having a cyclic structure
(-20°C s Tg < 60°C, 100 s Mn s 20,000)
Shell material: Coating resin for fixing
(b) Core material: Binder resin for heat fixing and binder
resin for pressure fixing
Shell material: Olefin polymer having a cyclic structure
(60°C s Tg s 180°C, 1,000 s Mn s 100,000)
(c) Core material: Olefin polymer having a cyclic structure
(-20°C s Tg < 60°C, 100 s Mn s 20,000)
Shell material: olefin polymer having a cyclic structure
(60°C s Tg s 180°C, 1,000 s Mn s 100,000)
A result of incorporating an olefin having a cyclic
structure in at least either of the shell material or the
core material in combination with the various crystalline
and non-crystalline resins given as examples of the above-
described fixing resins [A](1) and [B](1), which are
relatively compatible with the olefin polymer, the
transparency, low-temperature fixing ability, mechanical
impact resistance, and other characteristics of the olefin
polymer having a cyclic structure that are important in
terms of toner performance can be exhibited.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-30-
With the mode (c), in which olefin polymers having
a cyclic structure are used in both the shell material and
core material, the above-mentioned characteristics become
fully exhibited as toner performance.
The most preferable form of toner particles is one
in which the following olefin polymer having a cyclic
structure, that is, an ethylene-norbornene copolymer, with a
glass transition temperature (Tg) ranging from 40 to 59°C, a
number average molecular weight (Mn) ranging from 1,000 to
10,000, and a polydispersity (weight average molecular
weight (Mw) / number average molecular weight (Mn)) of 10 or
less and with which the copolymerization mole ratio of
ethylene to norbornene is from 85/15 to 95/5, is used as the
binder resin of the core material, and in which the
following olefin polymer having a cyclic structure, that is,
an ethylene-norbornene copolymer, which is soluble in methyl
ethyl ketone (MEK), has a glass transition temperature (Tg)
ranging from 60 to 80°C, a number average molecular weight
(Mn) ranging from 2,000 to 50,000, and a polydispersity
(Mw/Mn) ranging from 4 to 10 and with which the
copolymerization mole ratio of ethylene to norbornene is
from 75125 to 85/15, is used as the coating resin of the
shell material.
The microcapsule toner particle is preferably
prepared by reprecipitation method. More specifically, it
is the solvent reprecipitation method wherein a good solvent
solution having the binder resin and the colorant dissolved
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-31-
therein is dropped into a poor-solvent solution of the
coating resin of the shell material to cause the shell
material to precipitate around the core material.
Microcapsule toner particles may also be prepared
in accordance with a phase separation method as indicated
for example in JP-B-08-16793 and JP-B2-2631019.
(1) Method of preparation by the reprecipitation method
(Solvent reprecipitation method)
After adding and dissolving 16 to 20% by weight of
the olefin polymer having a cyclic structure that
constitutes the core material and 1 to 2% by weight of a
function imparting agent in 76 to 80% by weight of solvent
(mixed solvent of toluene and cyclohexane, etc.) at a
temperature of 25 to 30°C, 1 to 2% by weight of colorant is
dispersed using a bead mill, etc. to prepare a solution
(solution A).
On the other hand, a solution (solution B) is
prepared by dissolving 1.8 to 2.2% by weight of the olefin
polymer having a cyclic structure that constitutes the shell
material and 0.015 to 0.025% by weight of a charge control
agent in 98% by weight of MEK or other solvent.
In the next step, solution A is dropped from a
nozzle with numerous orifices of 20 to 30~,m diameter into
solution B with high velocity stirring to obtain a
precipitate, which is then passed through a multiple stage
filter of 2 ~,m, 0.5 ~,m, and 0.2 ~m and thereby separating
from the solvent. In the final stage, particles are formed
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-32-
by removing the residual solvent using a high-temperature
vacuum dryer.
Microcapsule toner particles are thus obtained
which are substantially spherical in shape, have an average
diameter of 4 to 10 ~,m and a particle size distribution of 2
to 12 um (corresponding to 3c~ where ~ = standard deviation),
and of which the thickness of the shell material is 0.2 to
0.5 ~,m (based on weight measurements by the solvent
separation method).
Hydrophobic silica is then externally added to be
rendered as a developer.
(2) Method of preparation by the phase separation method
An olefin polymer having a cyclic structure, acid-
modified olefin polymer having a cyclic structure, wax,
colorant, and charge control agent are melt kneaded. After
microdispersing hydrophilic silica as a protective colloid
with high-velocity stirring in hot water, solidification is
performed by cooling rapidly with a large amount of water.
The silica is then dissolved and removed by a basic aqueous
solution and the core material particles are obtained by
rinsing with water/methanol and then performing filtration.
Separately, an olefin polymer having a cyclic
structure, wax, and charge control agent are dissolved in a
ketone solvent, preferably MEK, a prescribed amount of the
above-mentioned core material particles is dispersed with a
homomixer, a prescribed amount of acetic acid is added, and
then under deep cooling, water is dropped in at a prescribed
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-33-
rate to reprecipitate the shell material onto the surface of
the core material particles.
Thereafter, rinsing with a mixed solution of water
and methanol, filtration, and drying are performed to obtain
microcapsule toner particles.
Hydrophobic silica is then externally added to be
rendered as a developer.
From a comparison of the above-described two
methods of preparation, it can be said that the
reprecipitation method excels in being more suitable for
industrial production in that a general purpose solvent of
low cost is used and drying is performed more readily due to
the difference in latent heat of the solvent and water, and
there is less mutual agglomeration of the toner particles.
BEST MODES FOR CARRYING OUT THE INVENTION
Though this invention shall be described more in
details by way of examples and comparative examples, these
examples and comparative examples do not limit the effective
scope of this invention at all.
Dry one-component toners and dry two-component
toners were prepared as described below.
Examples 1 to 4 are examples of preparation of
microcapsule toner by the reprecipitation method and Example
5 is an example of preparation of microcapsule toner by the
phase separation method.
Example 1
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-34-
Preparation of solution A (core material)
17% by weight of "Topas T-936" manufactured by
Ticona GmbH and having a glass transition temperature (Tg)
of 49°C and a number average molecular weight (Mn) of 2,000
was used as the olefin polymer having a cyclic structure, 1%
by weight of "Togas AG-07" manufactured by Ticona GmbH and
having a glass transition temperature (Tg) of 58°C and a
number average molecular weight (Mn) of 3,700 was used as
the acid-modified olefin polymer having a cyclic structure,
0.5% by weight of "BNT22H" manufactured by Nippon Seika and
0.5% by weight of "Ceridust 3715" (trade name) manufactured
by Clariant were used as a function imparting agent, and
these components were gradually added to and dissolved in
80% by weight of a mixed solvent of toluene and cyclohexane
(weight ratio: 50:50) at a temperature of 30°C and stirring
velocity of 200 rpm.
Beads (stainless steel powder manufactured by
Ashizawa, particle diameter: 500 ~,m) were then added to the
above solution, and 1% by weight of a black colorant
("Carbon Black MA-7" manufactured by Mitsubishi Chemical)
wa.s gradually added and dispersed with a stirring velocity
of 500 rpm to obtain solution A.
Preparation of solution B (shell material) .
2% by weight of "Togas AG-09" manufactured by
Ticona and having a glass transition temperature (Tg) of
67°C and a number average molecular weight (Mn) of 4,600 was
used as the olefin polymer having a cyclic structure, and
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-35-
this was dissolved along with 0.02% by weight of a charge
control agent ("Copy Charge NX" (trade name); manufactured
by Clariant) in approximately 98% by weight of methyl ethyl
ketone to obtain solution B.
Granulation process
The above-described solution A was dropped from a
nozzle with numerous orifices of 30 ~,m diameter .into
solution B with high-velocity stirring to form particles.
With regard to the rate of dropping, in the case
where the particles are to be made in a kettle of 500 liter
volume, 100 liters of solution A was gradually added by
dropping from 100 orifices at a rate of 5 liters/min. into
200 liters of solution B over 20 minutes to obtain a
precipitate.
The stirring velocity of solution B was set to
2000 rpm, and the stirring was continued for 10 minutes
after the completion of dropping of solution A. Thereafter,
the precipitate was passed through a multiple stage filter
of 2 ~u,m, 0.5 ~,m, and 0.2 ~,m and thereby separating from the
solvent, and then the residual solvent was removed by a
high-temperature vacuum dryer to obtain microcapsule toner
particles.
The average diameter of the toner particles
obtained was approximately 6 ~u,m and all particles were
distributed within a particle size classification of 2 to 12
~,m. Since size separation of coarse particles and very fine
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-36-
particles were not required, this method was found to be
excellent in terms of productivity.
Observations by a scanning microscope confirmed
that the particles have a substantially spherical shape,. and
the thickness of the shell material was calculated according
to the below-described weight measurements by the solvent
separation method to be 0.2 to 0.5 ~Zm.
With regard to the yield of the toner, the yield
after drying was 21.7 kg (yield of 92%) with respect to 100
liters (approximately 85.6 kg, of which the core material
polymer comprised 17.1 kg) of solution A and 200 liters
(approximately 162 kg, of which the shell material polymer
comprised 6.5 kg) of solution B (total solids 23.6 kg).
The yields of the toner by means of the
conventional mechanical milling method and the air impact
air flow method which uses a high-velocity air flow were
approximately 80% and approximately 75%, respectively, where
ultramicroparticles of 1 ~,m or less are formed. It was thus
found that the toner yield is improved significantly by the
above-described method.
The average particle diameter of the toner
particles was determined by a laser diffraction scattering
type particle size distribution measurement device ("LA-700"
manufactured by Horiba Seisakusho). The particle size
distribution was also measured by the same device, and
particles of 4 to 10 ~,m particle diameter were found to
share 95% on a volume basis and 75% on a number basis.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-37-
For the measurement of the thickness of the shell
material, 10 g of the toner particles were weighed out and
placed in 1 liter of methyl ethyl ketone, and after
dissolving the shell material by heating to 50°C and
stirring for 20 minutes, the solvent was removed by hot
filtration and the remaining weight was measured to
calculate the thickness of the shell material.
Example 2
Except for using the yellow colorant "Yellow HG"
(trade name) manufactured by Clariant as a colorant,
microcapsule toner particles were obtained in the same
manner as Example 1.
Example 3
Except for using the magenta colorant "Pink E02"
(trade name) manufactured by Clariant as a colorant,
microcapsule toner particles were obtained in the same
manner as the Example 1.
Example 4
Except for using the cyan colorant "Blue B02G"
(trade name) manufactured by Clariant as a colorant,
microcapsule toner particles were obtained in the same
manner as Example 1.
Example 5
Microcapsule toner particles were prepared as
described below by the phase separation method in reference
to JP-B1-8-16793 and JP-B2-2631019.
Preparation of core material particles
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-38-
85% by weight of "Togas T-936" manufactured by
Ticona was used as the olefin polymer having a cyclic
structure, 5% by weight of "Togas AG-07" manufactured by
Ticona was used as the acid-modified olefin polymer having a
cyclic structure, 2% by weight of a behenic acid amide wax
"BNT22H" (trade name) manufactured by Nippon Seika) and 2%
by weight of a mixed powder of oxidized and non-oxidized
polyethylene wax ("Ceridust 3715" (trade name) manufactured
by Clariant) were used as function imparting agents, and
these components, along with 5% by weight of a black
colorant ("Carbon Black MA-7" manufactured by Mitsubishi
Chemical) and 1% by weight of a charge control agent ("Copy
Charge NX" (trade name) manufactured by Clariant), were melt
kneaded at 120°C for 15 minutes with a kneader ("Rheomix
600" manufactured by Haake), and the mixture obtained was
transferred to a stainless steel container equipped with a
heater and maintained at 130°C.
Separately, water was placed in a homomixer
(manufactured by Tokushu Kika) and heated to and maintained
at approximately 95°C. 0.4% by weight of colloidal silica
("HDK N-30" manufactured by Wacker Chemie) were then added
and dispersed adequately by stirring.
The rotation speed of the homomixer was set to
8,500 rpm, and approximately 15 parts by weight (phr) of the
above-described melt mixture were added to the dispersion
medium of hot water and then stirring was continued for
approximately 15 minutes to form microparticles.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-39
Thereafter, the dispersion was poured onto the ice
prepared beforehand (of double the amount of the dispersion)
to rapidly cool and solidify the microparticles. An amount
of sodium hydroxide equivalent to the amount for
neutralization of the colloidal silica was then added to the
dispersion, stirring was performed with a propeller mixer
for 24 hours under room temperature to dissolve the
colloidal silica, and the basic solution and the solids were
separated by a centrifugal filter.
The slurry was then rinsed with a water/methanol
solution (50/50 wt.%), filtration was performed each twice,
and drying was performed with a hot air dryer set to 40°C to
obtain the core material particles.
The volume average particle diameter of these
particles was approximately 8 ~,m (measured with "LA-700"
manufactured by Horiba Seisakusho).
Preparation of shell material solution
A shell matexial solution for capsulation was
prepared using 95 parts by weight of the above-mentioned
"Topas AG-09" as the olefin polymer having a cyclic
structure, 2 parts by weight of a behenic acid amide wax
{"BNT22H" (trade name) manufactured by Nippon Seika) and 2
parts by weight of a mixed powder of oxidized and non-
oxidized polyethylene wax ("Ceridust 3715" (trade name)
manufactured by Clariant) as function imparting agents, 1
part by weight of a charge control agent ("Copy Charge NX"
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-40-
(trade name) manufactured by Clariant), and 2400 parts by
weight of methyl ethyl ketone.
A homomixer was equipped to a reaction tank with
jacket of 20 liter volume, 7.6 kg of the above-described
solution was fed into the reaction tank, and after cooling
to -25°C with stirring, 120 g of acetic acid were fed and
stirring was performed for 5 minutes.
2.0 kg of the above-described core material
particles were then fed into the reaction tank and after
dispersing adequately with a homomixer, and cold water of 0
to 5°C was dropped at a dropping rate of 10 g/minute. The
dropping rate was increased gradually to 100 g/minute at the
final stage, and approximately 3 kg of water were added
finally. The required time for this process was
approximately 2 hours.
Thereafter, the capsulation solution was separated
by a centrifugal filter and the capsule particles that were
separated by filtration were rinsed twice with
water/methanol (50/50% by weight), separated by filtration,
and dried at 40°C.
The volume average particle diameter of the
capsule particles was approximately 8.5 ~,m which was thus
clearly larger than that of the core material particles and
the diameter was enlarged due to capsulation.
A substantially similar thickness of shell
material (0.2 to 0.3 ~,m) was calculated by weight
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-41-
measurements by the above-described solvent separation
method.
0.5 parts by weight of hydrophobic colloidal
silica was added externally as a developer onto the
microcapsule toner thus obtained.
Comparative Example 1
A toner, which is a commercially available toner
prepared by the air impact milling method (jet milling
method) and to be more specific, is a toner for the copier
"FT-5520" manufactured by Ricoh was used and performance
evaluations were performed with the above-mentioned copier.
Comparative Example 2
A toner, which is a commercially available toner
prepared by the mechanical milling method, and to be more
specific is the toner for the printer "Magicolor 2CX" (trade
name) manufactured by QMS was used and performance
evaluations were performed with the copier "FT-5520"
manufactured by Ricoh.
Actual copies were made with the copier "FT-5520"
manufactured by using the microcapsule toners obtained in
the Examples 1 to 4 described above and the commercially
available toners of the Comparative Examples 1 and 2. The
results are as shown in Table 2.
(a) Anti-spent toner effect
Actual copying tests onto high-quality paper were
performed using the toner samples of the respective examples
and comparative examples. Copies were made until the toner
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-42-
components stuck to the developing sleeve and the
photoconductor reached to the allowable limit amount, and
comparisons were made with the number of sheets of paper
that had been copied onto at that point.
(b) Transfer properties
The efficiency of transfer from the photoconductor
onto high-quality paper, which is the substrate to be
copied, was measured based on the amount of toner recovered
after performing copying onto 10,000 sheets.
(c) Fixing ability
Imaging was formed on high-quality paper using
each toner, an unprinted paper of the same quality was
placed on the top of the printed paper and the printed image
was rubbed with a rubbing tester to be transferred forcibly
onto the unprinted paper.
The fixing rate for imaging was set to 150
. mm/second and the fixing temperature was set at 150°C.
The conditions of the rubbing test were set 20
reciprocations under a load of 2 pounds (approximately 907
g). After rubbing, the initial image density before rubbing
(A), the density of transfer onto unprinted paper (B), and a
density of a non-image area of paper (C) were measured using
a Macbeth type reflection densitometer, and the transfer
rate was determined by the formula, [(B-C)lA x 100(%)~. The
lower limit fixing temperature and lower limit fixing
pressure at which a transfer rate of 60% or more was
exhibited~were measured and compared.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-43-
(d) Image sharpness
The image sharpness of each toner was compared and
the gradation, thin-line resolution, and OHP light
transmittance were evaluated as follows.
Gradation
The gradation was evaluated by gray scale steps of
0 to 16 using image samples made by Dataquest Co.
Thin-line resolution
The thin-line resolving power was evaluated by a
thin line pattern of 0 to 600 dpi using image samples made
by Dataquest.
OHP light transmittance
An image was formed on an OHP film for PPC
manufactured by Fuji Xerox, the light transmittance at an
image area (A) and at a part without an image (B) were
measured, and the transmittance was indicated as A/B x
100(%)
(e) Preservation stability
After preserving the toner prepared by each
procedure for 8 hours under the conditions of 60°C and 50%RH
(relative humidity), the toner was passed through a mesh of
100 mesh for a fixed period of time, and the value obtained
by dividing the mesh residual with the amount of sample used
was indicated in %. Agglomeration of toner particles during
preservation will.render this value higher. The
agglomeration is caused mainly by the substances of low
melting point of 50°C or less contained in the toner
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-44-
composition. The symbol "o" indicates the mesh residual of
0.5% or less and "x" indicates the mesh residual exceeding
0.5%.
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-45-
a~
,5 O 01 O O 00 O N
X
'r1 O 01 O M O 01
N
.L~ O M r-I M
cCf
N
S-I O
ri
N
O
t~4'
U
W
N
o m o 0 00 0 0
'~I o o~ o ~r o o~ X
,-~
.+-1O d~ r1 M
(If
O
S-1 O
r1
(ti N
(2~
O
'n'
U
W
0 00 0 0 ~o o ~n
O N O r1 O 01
O 01 ,-i l0
O
W
Lf1
O O 00 O O l0 O Lt0
O N O rt O 01
O 01 e-I l0
O
W
d~
N
O O CO O O l0 O LC7
O N O r-I O 01
.O S~ O tr ~-1 l0
p1
H rti o
u~
W
M
O O O O O l0 O Ln
~ O N O ~-I O Q1
O 01 ~-i l0
C1
O
W
N
O O 00 O O l0 O Ln
O N O e-I O O1
O 01 r1 lfl
O
W
r-I
N
v
1-I .1.~U +~ ~ N s~
~ ~
s~ U '' ~ E~ ~ ~
_ ~ ~ O p '~ .~.1~
-I
~""I.I-~O O '~-II"IS,-Ir'IcCf ~ '~"'I'rI.I-~b~'~"'If~
N
tit ~-IU ~-i ''.~' ~-I C~.1,r-i''...1r-I~., O
.~r
J .I-~~ O 'r-I,~.atl1 f-1N i'-1ofI r-i r-IU1 'r1
U ~
.1-i .LlN U1 eUp., td''t~f~O f~ .h
w ~ 'r1
3 ~ 3 I~ .~rtt'~m pard
~ U W ~
o m ~ w x ~ '~~ '~ x s~ ~
== ~
.~ ~ ~ a~ a ~ H ~ o +~
, -
1 U7 ~ N N
U 'r-I
N H ~ ~ ~
+~ c ~ td N
~ 6 c
U
H H
~t',H W W
N in
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-46-
INDUSTRIAL APPLICABILITY
The toner for developing an electrostatically
charged image of the present invention is a microcapsule
toner particles composed of a core and a shell. Further, an
olefin polymer having a cyclic structure which is relatively
low in glass transition temperature and relatively low in
average molecular weight is used as the binder resin in the
core material and/or an olefin polymer having a cyclic
structure which is relatively high in glass transition
temperature and relatively high in number average molecular
weight~is used as the coating resin in the shell material.
Consequently the toner is applicable to pressure
heating fixing type copying equipment and it is good in
preservation stability, it produces sharp 'images of high
grade, and it is excellent in anti-spent toner effect,
transfer ability, fixing ability and offset-free properties.
Further, the toner of the present invention is
excellent in exhibiting a sufficient fixing ability even in
low-temperature heating type copying equipment.
Also, even with heat roller fixing type equipment,
the use of the toner of this invention enables significant
reduction of the heating calory to be achieved easily and
thus enables contributions to be made for the energy savings
of copying equipment.
Also, the supply of oil onto the heat roller
surface is not needed by incorporating a function imparting
CA 02407323 2002-10-22
WO 01/84248 PCT/JP00/02782
-47-
agent for mold release such as silicone oil or wax into the
shell material.
