Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to a liquid developer
for use in a liquid developing method as in electrophotography
or the like. An object of an aspect of this invention is to
provide a liquid developing method in which the degree of
charge of the toner particles and the charge polarity of the
toner particles may be altered in a controlled way.
In accordance with one aspect of this invention
there is provided a liquid developer comprising a highly
insulating carrier li~uid; toner particles comprising pigment
particles coated with resin soluble in the carrier liquid,
resin insoluble in the carrier liquid and dye functioning as
a polarity imparting agent; and a crude rubber of opposite
polarity to the polarity of the dye, said toner particles
and crude rubber being mixed in said carrier liquid.
The resin soluble in the carrier liquid and the
dye of the liquid developer thus constituted are solved in the
toner surface from the interior of the toner particles so as
to impart the polarity of the dye to the toner particles. On
the other hand, the crude rubber is dissolved in the carrier
liquid to surround the circumference of the toner particles
because the crude rubber has an opposite polarity to that of
the dye. As a consequence~ the degree of charge and the
charge characteristic of the toner particles can be altered
arbitrarily under control by controlling the amounts of dye
and crude rubber employed. For e~ample, if the amount of
crude rubber is maintained constant, while the amount of the
dye is increased, the toner particles will adopt the charge
characteristic imparted by the dye, whereas if the amount
of the dye is decreased, the toner particles will adopt the
charge characteristic imparted by the crude rubber. If the
~2- ~
1~3~;5
difference between the amount of rubber and the amount of
dye is increased, the charge of the toner particles will become
~;; larger, while if the difference therebetween is decreased, the
charge of the toner particles will become smaller.
The manufacturing process of the liquid develop-
er of this invention now will be described.
The pigment particles, resin soluble in the
carrier liquid, resin insoluble in the carrier liquid and dye
` are dissolved in a solvent consisting of liquid soluble in
water for solving them and liquid insoluble in water for solvin~
them.
; The toner solution thus produced is poured into
water or 5 to 10% v/v aqueous isopropyl alcohol solution, and
~` the mixture solution then is stirred.
Toner particles in small spherical state are
formed in the liquid due to the hydrophobic property of the
liquid that is insoluble in waterO The solution is filtered so
as to remove these spherical toner particles which are pigment
particles coated with resin soluble in carrier liquid, resin
insoluble in carrier liquid and dye.
The toner particles and the crude rubber are
mixed in the carrier liquid so as to form a liquid developer.
The carrier liquid is highly insulating and thus
may have a high electric resistance of the order of greater
than 1014 ~ cm. The carrier liquid also dissolves crude
rubber and may employ liquid of fatty or alicyclic hydrocarbon
group. For example, the carrier liquid may include
*
ISOPAR-H (Esso S.A.F.)
ISOPAR-G ( "
CHELLSOL (Shell Oil Company)
* trade marks
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:
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PEGASOL ~Mobil Oil Corp.)
~ *
SWASOL (Maruzen Oil Co., Ltd.)
The pigment may be carbon black coated with
resin insoluble in the carrier liquid. The pigment may be,for
example, graphitic carbon and the like. Specifically, the pig-
ment may include
MICROLITH C-K (Ciba-Geigy AG)
MICROLITH C-T ( "
As a resin functioning to accelerate the bonding
of the pigment to the crude rubber is a substance soluble in
the carxier liquid such as, for example, acrylic resins.
; Specifically, the resin may include
ACRYBASE MM 2005 (Fujikura Kasei Co., Ltd.)
ACRYBASE MS 2008
As to the dye, there may be selected a substance
exhibiting opposite polarity to that of the crude rubber in the
carrier liquid. For example, the dye may include oil soluble
dye such as:
oil black,
nigrosine,
crystal violet,
Fast Black, etc.
The crude rubber may be the type called "pale
crepe".
Some Examples now will be described by way of
illustration only.
Example 1
( 1) MICROLITH C--K 10 g
(2) ACRYBASE MM 2005 0.6 g
30 (3) oil black 0.06 g
~4) crude rubber 0.2 g
* trade marks
z~L~s
* *
-~ (1) MICROLITH C-K, (2) ACRYBASE MM 2005, and
.~ .
: (3) oil black were dissolved in a mixed solution of 15 g of
` trichloroethylene and 300 g of tetrahydrofuran. Approximately
100 ml of the resulting solution was dispersed in a mixer
containing 1,600 ml of 10% aqueous isopropyl alcohol solution.
The solution thus dispersed was poured into 2,000 ml of 10~
a~ueous isopropyl alcohol solution and agitated for approximate-
ly l hour.
After agitation the solution was applied to a
centrifugal separator and was centrifugally separated at an
acceleration of 3,000 g for approximately 3 minute~. The
supernatant liquid of the solution was removed, and the precip-
` itate thereof was vacuum dried for several hours.
- The powder thus obtained by vacuum drying was
kneaded with a spatula in OSOPAR-H liquid and crude rubber
and was dispersed in the ISOP~R-H liquid to obtain a liquid
developer.
The polarity of the developer thus obtained was
negative. The curve of the surface potential versus the image
2-0 concentration showed a substantially rectilinear relationship
between 0 and 100 volts. When the picture image was developed
under conditions of distance between the opposi'ce developing
electrodes o~ l mm and developing time of 10 sec., the image
concentration or density was in high transmitting density,
such as 0.8 in latent image of +50 volts and l.9 of +100 volts
on the Mylar of 100 microns. The volumetric resistance of
the image also exhihited high resistance, such as 1 X 10 ~cm
- of the resistance value at one minute after 100 volts were
applied thereto.
* trade marks
2~S
In addition, using a chamber employing CC14
liquid as an X-ray absorbent, the image was projected with X-ray
of aluminum echelon grating of 1 mm. difference and 10 stages.
The chamber was composed of an aluminum electrode and an
` aluminum plate disposed oppositely to the aluminum electrode
*
at an interval of 1 ~n coated with a Mylar film of 100 microns
as an image receiving film together with CC14 liquid filled in
the space of 1 mm. therebetween.
The aluminum electrode was grounded, and a high
voltage of -8 KV was applied to the image receiving film. Then
75 KVP of tube voltage was applied to 1 m. from line voltage
supply, and X-rays in the amo~nt of 10 MAS were projected to the
~ilm so as to produce a positive image of aluminum echelon
grating on the film. When this latent image was developed with
- the liquid developer produced according to this invention, the
concentration difference of 10 stages could clearly be observed.
In addition, PET film 15 microns thick was
provided on an electroconductive substrate, and 500 volts was
applied between a needle electrode and the substrate. Thus,
~- 20 the image was investigated in recording with the needle
electrode so that the image was developed with the above devel-
oper with the result that the portion o~ the image of 150 volts
as the image potential obtained 1~8 of optical image con~entra-
tion with this developing.
Example 2
*
(1) MICROLITH C-K 10 g
; (2) ACRYBASE MM 2005 0u6 g
(3) oil black 0.3 g
(4) crude rubber 0.1 g
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* trade marks
L6
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-
The liquid developer was produced in the same manneras that disclosed in the aforementioned Example 1 using the
; above components so as to obtain a developer of positive
polarity. The properties of the developer thus produced also
were measured by producing a negative image according to the
method similar to that disclosed in Example 1, and substantial-
ly the same results as those in Example 1 were obtained.
It should be understood from the foregoing descrip-
tion that the degree of charge and the charge characteristic
of the toner particles can be altered arbitrarily under control
by increasing or decreasing the amounts of the dye and the
crude rubber.
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