Note: Descriptions are shown in the official language in which they were submitted.
- ~ ~~
1 4~23
SPEC IFICATION
TONER RES IN
TECHNICAL FIELD
~his invention relates to a resin suitable for
use in an electrophotographic toner which is adapted to
develop electrophotographic latent images in electro-
photography, electrostatic recording, electrostatic
printing and the like.
BACKGROUND ART
In electrophotography, the copying speed tends
to increase further in recent years to meet the ever
increasing quantity of information to be dealt with.
On the other hand, it is desired in electrophotography
that copied marks have the ~ame quality from the first
copy to the several ten thousandth copy.
In order to obtain vivid marks even in high-
speed copying, it has conventionally attempted to
improve toner resins by placing importance on heat-
melting characteristics;~such as low-temperature fixing
property and offsetting resistance as well as the
electrification stability of toners.
With a view toward attaining such a goal, the
present inventors have already developed a new
- 2 - I 3 ~ 4 ~ 2;~
technique in which a styrene resin having ~ lower
molecular weight (Mn: 1,OO0 - 5,000) is used as a toner
resin (Canadian patent application serial no. 552,738).
Hcwever, polyvinyl chloride (PVC) resistance has
recently come to the surface as a new problem. When a
sheet of paper bearing a price or the like copied
thereon by way of example is left over under a load on
a PVC sheet for one week, some of the marks copied is
caused to transfer to the PVC sheet and for example,
one zero ~0) disappears from the copied paper sheet.
This will certainly causes a serious problem because
the price has been reduced by one figure. Further, the
PVC sheet has been smeared by the sticky toner
deposited thereon, thereby causing another problem.
As a result of a follow-up test, it was found
that the above-mentioned technique developed by the
present inventors is not fully satisfactory in PVC
resistance although it is extremely good in low-
temperature fixing property, offsetting resistance,
mark vividness and other properties. As possible
reasons for this insufficiency, it may be mentioned
that since the styrene-base resin has strong absorbing
capacity for a plasticizer such as dioctyl phthalate in
the PVC sheet, the plasticizer is caused to migrate
into the toner and the toner is plasticized as a
result.
~'
3 1 31 4423
DISCLOSURE OF THE INVENTION
An object of an aspect of this invention is to
provide a toner resin, which has excellent fixing
property and also significantly-improved PVC resistanee,
by dissolving a low molecular polymer in a monomer,
dispersing the resultant mixture in an aqueous system
and then polymerizing same.
An aspect of the invention is as follows:
A toner resin comprising as a principal component a
polymer obtained by mixing 20 - 80 parts by weight of a
low molecular weight polymer having a number average
molecular weight of 1,000 - 5,000 and a glass transition
temperature (Tg) of 40 - 75C, wherein said low
molecular weight polymer is prepared by polymerizing
monomers selected from the group consisting of acrylic
esters, methacrylic esters, aromatic vinyl monomers,
dialkyl esters of unsaturated dibasic acids, vinyl
esters, nitrogen-containing vinyl monomers, unsaturated
carboxylic acids,
monoesters of unsaturated diearboxylie acids,
styrenesulfonic aeid, acrylamide, methacrylamide, N-
substituted acrylamides, N-substituted methacrylamides,
and acrylamide propanesulfonic acid, 80 - 20 parts by
weight of a vinyl monomer, the sum of said low molecular
weight polymer and vinyl monomer being 100 parts by
weight, 0.01 - 5 parts by weight of a polymerization
initiator and 0 - 3 parts by weight of a crosslinking
agent, dispersing the resultant mixture in water and
then polymerizing the same.
BEST MODE FOR CARRYING OUT THE INVENTION
The low molecular polymer useful in the praetiee of
this invention may preferably be that produeed by
feeding a vinyl monomer, a polymerization initiator and
-
~ 4 ~ 131~423
a solven~ continuously into a system of 190 - 230C
and polymeri~ing them in a liquid state by solution
polymerization. Illustrative examples of the vinyl
monomer include acrylic esters such as methyl acrylate,
S ethyl acrylate, propyl acrylate, butyl acrylate, octyl
acrylate, cyclohexyl acrylate, lauryl acrylate, stearyl
acrylate, benzyl acrylate, furfuryl acrylate, tetra-
hydrofurfuryl acrylate, hydroxyethyl acrylate, hydroxy-
butyl acrylate, dimethylaminomethyl acrylate and
dimethylaminoethyl acrylate; methacrylic esters such as
methyl methacrylate, ethyl methacrylate, propyl
methacrylate, butyl methacrylate, octyl methacrylate,
lauryl methacrylate, stearyl methacrylate, cyclohexyl
methacrylate, benzyl methacrylate, furfuryl methacryl-
ate, tet.rahydrofurfuryl methacrylate, hydroxyethylmethacrylate, hydroxypropyl methacrylate, hydroxybutyl
methacrylate, dimethylaminomethyl methacrylate and
dimethylaminoethyl methacrylate; aromatic vinyl
monomers such as vinyltoluene, ~-methylstyrene, chloro-
styrene and styrene; dialkyl esters of unsaturateddibasic acids, such as dibutyl maleate, dioctyl
maleate, dibutyl fumarate and dioctyl fumarate î vinyl
esters such as vinyl acetate and vinyl propionate;
nitrogen-containing vinyl monomers such as acrylo-
nitrile and methacrylonitrile; unsaturated carboxylicacids such as acrylic acid, methacrylic acid and
- 5 ~ ~ 2J
cinnamic acid; unsaturated dicarboxylic acids such as
maleic acid, maleic anhydride, fumaric acid and
itaconic acid; monoesters of unsaturated dicarboxylic
acids, such as monomethyl maleate, monoethyl maleate,
monobutyl maleate, monooctyl maleate, monomethyl
fumarate, monoethyl fumarate, monobutyl fumarate and
monooctyl fumarate; st~renesulfonic acid; acrylamide;
methacrylamide; N-substituted acrylamides; N-
substituted methacrylamides; acryamide propanesulfonic
acid; etc. At least one of these monomers is used.
Among these, acrylic esters, methacrylic esters,
styrene, dialkyl Eumarates, acrylonitrile, methacrylic
acid, cinnamic acid, the ~umaric monoesters,
acrylamide, methacrylamide are particularly preferred.
A polymerization initiator is usually employed
when the low molecular polymer is produced by poly-
merizing the vinyl monomer in the present invention.
~s exemplary polymerization initiators use~ul in the
practice of this invention, may be mentioned azo type
initiators such as 2,2'-azobisisobutylonitrile, 2,2'-
azobis~4-methoxy-2,4-dimethylvaleronitrile), 2,2'-
aæobis(-2,4-dimethylvaleronitrile), 2,2l-azobis(-2-
methylbutylonitrile), dimethyl-2,2'-azobisisobutylate,
l,l'-azobis(l-cyclohexanecarbonitrile), 2-~carbamoyl-
azo)-isobutylonitrile, 2,2'-azobis(2,4,4-trimethyl-
pentane), 2-phenylaæo-2,4-dimethyl-4-methoxyvalero-
- 6 - 13~423
nitrile and 2,2'-azobis(2-methylpropane); ketone
peroxides such as methyl ethyl ketone peroxide, acetyl
acetone peroxide and cyclohexanone peroxide; peroxy
ketals such as l,l-bis(t~butylperoxy)-3,3,5-trimethyl-
cyclohexane, l,l-bis(butylperoxy)cyclohexane and 2,2-
bis(t-butylperoxy)butane; hydroperoxides such as
t-butyl hydroperoxide, cumene hydroperoxide and
1,1,3,3-tetramethylbutyl hydroperoxide; dialkyl
peroxides such as di-t-butyl peroxide, t-butyl cumyl
peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-
butylperoxy)hexane and ~,a'-bis(t-butylperoxyiso-
propyl)benzene; diacyl peroxides such as isobutyryl
peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl
peroxide, 3,5,5-trimethylhexanoyl peroxide, benæoyl
peroxide and m-toluoyl peroxide; peroxy d.icarbonates
such as di-isopropylperoxy dicarbonate, di-2-ethyl-
hexylperoxy dicarbonate, di-n-propylperoxy dicarbonate,
di-2-ethoxyethylperoxy carbonate, di-methoxyisopropyl-
peroxy dicarbonate and di(3-methyl-3-methoxybutyl)-
peroxy dicarbonate; sulfonyl peroxides such as acetyl-
cyclohexylsulfonyl peroxide; peroxy esters such as
t-butyl peroxyacetate, t-butyl peroxyisobutylate,
t-butyl peroxyneodecanoate, cumyl peroxyneodecanoate,
t-butyl peroxy-2-ethylhexanoate, t-butyl peroxylaurate,
t~butyl peroxybenzoate, t-butyl peroxyisopropyl-
~ 7 ~ l 3 1 4 4 23
carbonate and di~t-butyl diperoxyisophthalate; and so
on. It is particularly preferred to use a polymeriza-
tion initiator of the dialkyl peroxide type such as
di-t-butyl peroxide, t-butyl cumyl peroxide or dicumyl
peroxide among the above-exemplified polymerization
initiators. The polymerlzation initiator may generally
be used in an amount of 0.01 - 10 parts by welght per
100 parts by weight the vinyl monomer charged, although
it varies depending on the reaction temperature.
As a process for producing the low molecular
polymer by polymerizing the vinyl monomer with the
polymerization initiator in the present invention,
solution polymerization is preferred as mentioned
above. As a solvent useEul in the practice of the
polymerization, may be mentioned an aromatic
hydrocarbon such as benzene, toluene, ethylbenzene,
orthoxylene, metaxylene, paraxylene or cumene, ethyl
TM
acetate, Solvesso ~lO0 (trade mark ; product of Esso
TM
Kaga~u K.K.), Solvesso #150 (trade mark ; product of
Esso Ragaku K.K.), or the like. They may generally be
used either singly or in combination. It is also
possible to choose other solvents in order to regulate
the molecular welght.
Taking the production of a low molecular weight
polymer by solution polymerization by way of example, a
further detailed description will hereinafter be made.
~.
~ 8 - I 3 1 ~ 4 ~3
As an exemplary process, a vinyl monomer is subjected
to single-stage or multi-stage polymerization by
continuously charging a homogeneous solution of the
vinyl monomer, a solvent and a polymerization initiator
into a pressure reactor filled up with a mixed solvent
and heated to 190 - 230C in advance while maintaining
constant the internal pressure of the reactor. ~ere,
it is suitable to provide a pressure control valve,
which detects the internal pressure and either opens or
closes as needed, with a discharge outlet for the
polymerization mixture so as to maintain the internal
pressure constant. Then, while maintaining at the
polymerization temperature the temperature around the
outl~t, the polymerization mixture is flashed
continuously into a vacuum system of about 0 - 200 mmHg
so that the solvents and the like are allowed to
evaporate. ~s a result, the resultant low molecular
polymer and the mixed solvent are separated from each
other, thereby obtaining the low molecular polymer in a
solid form. As another process exemplary process, a
homogeneous solution of a vinyl monomer, a solvent and
a polymerization initiator is continuously charged into
a pressure vessel, which has been charged with a small
amount o~ the solvent in advance, while maintaining the
internal pressure constant. When the vessel has been
filled up substantially, the feeding is stopped and the
1 31 4423
solution of the resultanL low molecular polymer is
flashed into a vacuum system. Thereafter, the low
molecular polymer is collected in the same manner.
The low molecular polymer obtained in the above
manner is supposed to have a number average molecular
weight of 1~000 ~ 5,000, with 1,500 - 2,800 being
preferred. If it is greater than 5,000, it is
di~icult to achieve fixing with a smaller heat
quantity. If it is smaller than 1,000 on the contrary,
it is impossible to obtain a glass transition tempera-
ture (Tg) of at least a predetermined level, leading to
poor blocking resistance. Further, the glass transi-
tion temperature (Tg) oE the above low molecular
polymer is required to be 40 - 75C, preferably, 45 -
70C~ Any glass transition temperatures lower than40C result in resins, the blocking resistance of
which is so poor that the resins are unsuitable for the
production of toners. I the glass transition tempera-
ture is higher than 75C on the other hand, the fixing
property under a smalle.r heat quantity is deteriorated,
thereby failing to obtain any resin intended for use in
the present invention.
In the present invention, the ratio of the low
molecular polymer to the vinyl monomer in which the
polymer is diRsolved is 20/80 - 80/20, preferably,
30/70 - 70/30 in terms of weight ratio. If the low
- lo - ~ 3 1 ~2~
molecular polymer is used in an amount smaller than
20/80, it is impossible to exhibit fixing property
under a smaller heat quantity. If its ratio is greater
than 80/20 on the other hand, the strength of the
resulting resin is reduced, and a toner making use of
such a resin is easily rubbed off for the lack of
sufficient strength even when the toner can be fixed.
Moreover, the toner undergoes offsetting to impair the
quality of marks.
In the present invention, the low molecular
polymer obtained in the above-described manner is
dissolved in the vinyl monomer, followed by further
polymerization. ~s a polymerization process, solution
polymerization, emulsion polymerization or suspension
polymerization is employed generally. Suspension
polymerization which is carried out in a state
dispersed in an a~ueous system is however used in the
present invention. Solution polymerization is not
considered to be preferable, because this process is
difficult to achieve any high molecular weight due to a
chain transfer by a solvent and even if a high
molecular weight should be achieved, the resulting
resin is too viscous to permit easy handling. Emulsion
polymerization is not applicable on the other hand,
because the low molecular polymer is contained in the
- 11 - I 3 1 ~423
vinyl monomer and emulsification is hence not ~easible.
Accordingly, the simplest suspension polymerization is
used. Namely, the aforementioned low molecular polymer
is mi~ed and dissolved under stirring in the vinyl
monomer described above. After addition and
dissolution of the crosslinking agent and a small
amount of the polymerization initiator, water and a
dispersion stabilizer such as polyvinyl alcohol or
gelatin are addedO The system is then converted into a
suspended state, followed by polymerization under heat.
It is preerable to use a crosslinking agent in
suspension polymerization. The PVC resistance can be
improved significantly by using a crosslinking agent.
As usable crosslinking agents, may be mentioned
compounds copolymerizable with the vinyl monomer
described above. It is possible to use, for example,
divinylbezene, ~poly)ethylene glycol diacrylate,
(poly)ethylene glycol dimethacrylate or the like. As
the crosslinking agent is used in a greater amount, the
gel content increases and the PVC resistance becomes
better. It is preferable to use the crosslinking agent
in an amount of 0~05 - 3 parts by weight, more
preferably, 0.05 - 1 part by weight per 100 parts by
weight of the sum of the low molecular polymer and
vinyl monomer. Any amounts smaller than 0.05 part by
weight are too little to bring about substantial
- 12 - 1 31 ~42:3
effects. On the other hand, any amounts greater than 3
parts by weight result in an increase to the viscosity,
whereby the flow characteristics under heat are
deteriorated and more difficulties are encountered in
achieving the fixing under a smaller heat quantity.
Incidentally, the term "gel content" as used herein
means the content of an insoluble matter which occurs
upon dissolution of a resultant polymer in tetrahydro-
furan (THY). The content of such an insolu~le matter
may preferably be 2 - 4~ wt.%.
As a polymerization initiator useful in the
above suspension polymerization, the above-exemplified
polymerization initiators are all usable. Preferable
polymeriæation initiators are also identical to those
mentioned above. ~s khe polymerization initiator, it
is preferable to use at least two polymerization
initiators in combination, one being an ordinary
polymerization initiator employed to promote the
polymerization reaction and the other a polymerization
initiator used for reducing any remainin~ portion of
the monomer. ~s the latter polymerization initiator, a
polymerization initiator having a half--life decomposi-
tion temperature higher than that of the former poly-
merization initiator is employed usually. Regarding
their amounts, it is preferable to use the former in an
amount of 0.01 - 4.0 parts by weight and the latter in
- 13 - ~ 3 1 ~ 4 23
an amount o 0 - 1.0 part by weight, both, per 100
parts by weight of the sum of the low molecular polymer
and vinyl monomer. They may hence be used in a total
amount of 0.01 - 5 parts by weight per 100 parts by
S weight of the sum of th~ low molecular polymer and
vinyl monomer. Any total amounts smaller than 0.01
part by weight re~uire too much time for the polymeri-
zation, whereas any to-tal amounts greater than 5 parts
by weight encounter difficulties in increasing the
molecular weight of the polymer and moreover lead to
more cleavage residue of the polymerization initiators
so that adverse effects are given to certain electrical
characteristics.
When the vinyl monomers with the low molecular
polymer, crosslinking agent and polymerizat.ion
initiator dissolved therein is dispersed in an aqueous
system in the present invention, it is possible to use
a dispersion stabilizer such as polyvinyl alcohol or
gelatin, a surfactant, a pH modiEier, and an inorganic
additive such as calcium phosphate or magnesium
carbonate in order to stabilize particles to be
suspended.
The resulting aqueous dispersion is then heated
to 60 90C, at which polymeri~ation is allowed to
proceed. The polymerization is thereafter conducted at
80 - 120C in order to remove any remaining portion of
- 14 - 1 31 ~412
the monomer. After completion of the polymerization,
the polymerization mixture is washed thoroughly to
remove the dispersion stabilizer. Subsequent filtra-
tion and drying can provide a toner resin according to
this invention.
A toner, to which the resin of this invention is
applied, 15 a powder-like dry toner basically. The
above-described resin as a principal component of the
toner is hence required to be solid at xoom
temperature. It is also required that after formulation
into a toner, the resin does not cause blocking even
when left over for a long period of time. From such
viewpoints, the glass transition temperature of the
resin may pre~erably be at least 40C, with at least
50C being more preferred. From the standpoint of
low-temperature fixing property, it is pre~erable that
the resin softens at a temperature as low as feasible.
In view of this preferable requirement, the glass
transition point may preferably be not higher than
90C, notably, 80C or lower.
Within ranges not impairing effects of the
present invention, the resin of this invention may be
added with one or more o~ blending resins - such as
polyvinyl chloride, polyvinyl acetate, polyolefins,
polyesters, polyvinyl butyral, polyurethanes. poly-
- lS - 1 3 1 ~ 4 2:~
amides, rosin, modi~ied rosin, terpene resins, phenol
re~ins, aliphatic h~drocarbon resins, aromatic
petroleum resins, paraffin wax and polyolefin waxes -
and one or more additives as needed.
The resin o~ this invention may be formulated
into a toner by mixing it with a coloring agent. As
usable exemplary coloring agents, may be mentioned
black pigments such as carbon black, acetylene black,
lamp black and magnetite; as well as organic pigments
and other inorganic pigments known in the art, such as
chrome yellow, yellow iron oxide, Hansa Yellow G,
quinoline yellow lake, Permanent Yellow NCG, molybdenum
orange, Vulcan Orange, Indanthrenes, Brilliant Orange
GK, red iron oxide, Brilliant Carmine 6B, alizarin
lalce, methyl violet lake, Fast Violet B, cobalt blue,
alkali blue lake, phthalocyanin blue, Fast Sky Blue,
Pigment Green B, malachite green lake, titanium oxide
and zinc white. They may each be used in an amount of
5 - 250 parts by weight per 100 parts by weight of the
resin.
The toner resin of this invention may be selec-
tively added, for example, with nigrosine, a known
charge control agent led by a metal-containing azo dye,
a pigment dispersant, an offset inhibitor and the like
and may then be converted into a toner by a method
known per se in the art. Name~y, the resultant
- 16 - I 3 1 4 ~ 23
resin mixture with the above various additives
incorporated therein is premixed in a powdery form,
kneaded in a heated and melted state by a kneader such
as hot roll, Banhury mixer or extruder, cooled,
comminuted finely by means of a pulverizer, and then
classified by a pneumatic classifier to collect
particles, generally, in a range of 8 - 20 ~m as a
toner.
The present invention will hereinafter be
described in further detail by the following Examples,
in which all designations of "part" or "parts" and "%"
mean part or parts by weight and wt.% unless otherwise
specifically indicated.
The measurement of each number average molecular
weight by gel permeation chromatography (GPC) was
conducted under the following conditions:
GPC apparatus: JASCO TWINCLE HPLC
Detector: SHODEX RI-SE-31
Column: SHODEX GPCA-80M x 2 + KF-802 x 1
Solvent: Tetrahydrofuran (T~F)
Flow Rate: 1.2 m~/min
Sample: 0.25% T~F solution
Copying characteristics were determined under
the following conditions by using a photographic
TM
copying machine EP~70 (trade mark ; manufactured by
- 17 - I 3 1 ~t423
MINOLTA CAMERA CO., LTD.) which was equipped with a
TEFLON(trade mark)-coated hot roll.
Fixing~prc~erty:
An eraser ("MONO", trade mark; plastic eraser
produced by K.K. Tombo Enpitsu) was reciprocated 20
times under a constant load between a solid black area
and the white background of each copy. The degree of
separation of the toner from the solid black area and
the extent of smear of the white background were
observed. The following evaluation standard wa~
followed.
: Not separated at all; excellent.
: Separated very little; good.
Q: Separated slightly; fair.
X: Separated, substantial smear; poor.
Background smear-
.
In a continuous copying operation, the white
background of the 100th copy and that of the 10,000th
copy were compared. The background smear was evaluated
in accordance with the degree of smear of the white
background of the latter copy worsened due to scattered
toner and the like. Results were ranked in accordance
with the following standard.
: Good.
Q : Smear was noticeable through a magnifier of
x30 magnification, fair.
- 18 - l 3l ~ a 2 3
X: Smear was noticeable by the naked eyes, poor.
Offsetting resistance:
The term l'offsetting" as used herein means a
phenomenon or problem that a toner adheres partly on a
fixing roll and after full single rotation of the roll,
the toner then adheres the white background of the
paper sheet thereby to smear the paper sheet. The
offsetting resistance upon continuous copying of 10,000
sheets was ranked in accordance with the following
standard.
: No offsetting.
X: Offsetting occurred.
_locking resistance:
-
Toners were left over at 50~C for 1 week.
Their blocking resistance was evaluated in accordance
with the following standard.
: Blocking not occurred at all.
~: Some blocking occurred but disintegrated by
a slight force.
20X: ~locking occurred and not disintegrated by
a slight force.
PVC resistance:
A PVC sheet was placed over each copied paper
sheet and a weight of lO0 g/cm2 was placed further on
the upper side of the PVC sheet. After allowing them
- 19 - 1314423
to stand at ~0C for 1 week, the PVC sheet was peeled
off. It was observed how the PVC was peeled off. The
extent o~ toner adhesion was also observed.
Observation results were ranked in accordance with the
S following standard.
~: No reslstance was experienced at all upon
peeling off PVC sheet from its correspond-
ing copied paper sheet. No changes were
observed at all on both PVC sheet and copied
paper sheet.
o: PVC sheet was free from deposition of its
corresponding toner but was loudly peeled
off. A portion of the toner became viscous.
~: Some toner was transferred to PVC sheet but
lS most of the toner still remained on the
copied paper sheet.
X: A ma~ority of toner moved to PVC sheet.
Example 1:
A homogeneous solution containing 0.5 part of
di-t-butyl peroxide per 100 parts of styrene in a mixed
solvent composed of 70 parts of styrene and 30 parts of
a mixed solvent of xylene and ethylbenzene was charged
continuously at a rate of 750 cc/hr into a 5-~ reactor
whose internal temperature and pressure were maintained
at 210C and 6 kg/cm2 respectively, whereby polymeriza-
131~423
tion was carried out. The polymerization mixture was
Elashed into a vessel of 200C and 10 mmHg so as to
distill off the solvent.
The number average molecular weight of a low
molecular polymer (A) thus obtained was 2,100, while
its Tg was 57C.
Fifty parts of the thus-obtained low molecular
polymer (A) were dissolved together with 30 parts of
styrene in 20 parts of n-butyl methacrylate, followed
by further addition of 0.5 part of benzoyl peroxide,
0.2 part of PERBUTYL I (trade mark ; t-butyl peroxy-
isopropylcacbonate produced by Nippon Oil and Fats Co.,
Ltd.) and 0.1 part of ethylene glycol dimethacrylate.
They were dissolved uniformly. The resultant mixture
was poured into 1,000 cc of water which contained 1
part of poly~inyl alcohol and 5 parts of calcium
hydrogenphosphate, so that the mixture was dispersed
into a suspended state. The dispersion was heated to
80C, at which polymerization was allowed to proceed
for 8 hours. The polymerization mixture was then
heated to 120C under pressure, at which the remaining
monomer was polymerized for 3 hours. Water was
filtered off, and the resultant resin was washed twice
with water and was then dried.
The thus-obtained resin (100 parts) ~as dispers-
- 21 - 1 31 ~,2 7`
ed and mixed with 7 parts of carbon black (MA-100,
trade name; product of Mitsubishi Chemical Industries,
Ltd.), 2 parts of a charge control agent (Spiron Black
TM
TRH, trademark ; product of Hodogaya Chemical Co.,
Ltd.) and S parts of polypropylene wax (Viscohol 550P,
trade mark ; product of Sanyo Chemical Industries, Ltd.)
in a Henschel mixer to obtain a toner in the form of a
lump. After grinding it coarsely into about 1 mm
granules, the granules were comminuted finely in a jet
mill and then classified by a pneumatic classifier, so
that toner particles of 5 - 20 ~m (average particle
size: about 11 ~m) were obtained.
In a twin-shell blender, 4 parts of the above
TM
toner, 100 parts of a ferrite type carrier (F-150,
5 trade ~rk; product oE Nihon Teppun K.K.) and 0.2 part
TM TM
of Aerosil ~trade mar~, type: R-972 (trade mark );
product of Japan Aerosil Co., Ltd.] were blended
together into a two-component developer.
The copying applicability of the developer was
investigated. Results are shown in Table 1.
Examples 2 - 5 & Comparative Examples 1 and 2:
Toners were separately produced in the exactly
same manner as in Example 1 except that the polymeriza-
tion temperature of the low molecular polymer was
25 chang~d to 190, 200, 220, 230, 180 and 240C respec~
- 22 - 1 3 ~ ~ 4 23
tively. Their copying applicability was thereafter
investigated. Results are summarized in Table 1.
Comparative Example 3:
Suspension polymerization was conducted in
exactly the same manner as in Example 1 except that the
low molecular polymer (A) was not dissolved in Example
1. A resin thus obtained was washed with water and
then dried. Using a mixture composed of 50 parts of
the thus-obtained resin ~B) and 50 parts of the low
molecular polymer (A), a developer was obtained in
exactly the same manner as in Example 1. The copying
applicability of the developer was investigated.
Results are also shown in Table 1.
Examples 6 and 7 & Comparative Examples 4 and S:
Toners were separately produced in exactly the
same manner as in Example 1 except that the ratio oE
the low molecular polymer ~) to the vinyl monomer,
which were subjected subsequently to suspension
polymerization, was changed to 70/30, 30/70, 90/10 and
10/90 respectively. Their copying applicability was
investigated. Results are summarized in Table 2.
Comparative Example 6:
A toner was produced in e~actly the same manner
as in Example 1 except that 56 parts of styrene and 14
parts of butyl acrylate were used in lieu of 70 parts
of styrene. Its copying applicability was investigat-
- 23 - ~31~23
~d. Results are also shown in Table 2.
Examples 8 - 11 & Comparative Examples 7 and 8:
Toners were separately produced in exactly the
same manner as in Example 1 except that the conditions
for suspension polymerization were changed to those
respectively shown in Table 3-1. Their copying
applicability was investigated. Results are summarized
in Table 3-2.
- 24 - 1 ~ 1 4~ 23
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