JP3525627B2 - Pigment composition for liquid toner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] TECHNICAL FIELD The present invention relates to a pigment for a liquid toner.
The present invention relates to a method for producing a composition. [0002] 2. Description of the Related Art According to a wet electrophotographic printing method, a printing speed is high.
Degree is less than commercial offset rotary press, but general dry type
Much larger than copiers, with commercial web offset presses
Differently, with no plate replacement, reduced printing cost, and
High image quality equivalent to a photograph (resolution of 800 DPI or more)
Can be obtained. For this type of development,
So-called liquid toner is used, which is electrically insulating
It consists of a liquid and pigment fine particles dispersed therein. here
The above resin is used for dispersing and fixing pigment fine particles.
It is used by being dissolved in an insulating liquid. [0003] SUMMARY OF THE INVENTION
When the zeta potential is low, insufficient print density or halftone dot
Therefore, how to solve this problem is important.
This is one of the key issues. [0004] Accordingly, the present inventor has set forth the above
Seeds to obtain a pigment composition for liquid toner
After various investigations, the present invention has been reached. That is, the present invention
The point is that carbon black and resin are dissolved in a non-aqueous solvent.
Dispersed as carbon black.
The value obtained by dividing the total oxygen content obtained by the volatile composition at ℃ by the specific surface area
Is 0.20 to 0.40 mg / m^TwoIs a carbon bra
And a pigment composition for liquid toner using a liquid. [0005] BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, in the toner pigment composition of the present invention, carbon
As black, the total determined by the volatile matter composition at 1500 ° C.
The value obtained by dividing the amount of oxygen by the specific surface area is 0.20 to 0.40 mg.
/ M^TwoIt is necessary to use carbon black
You. The surface of carbon black particles has hydroxyl groups.
And carbonyl and carboxyl oxygen functional groups
However, depending on the amount, the resistance when blended with resin etc. is large
Changes to Usually, the oxygen functional group is measured by volatile composition,
The amount of hydroxyl group or carbonyl group is CO or carboxyl group
Amount of CO_TwoAnd the total oxygen content is CO and
CO _TwoIt is the amount converted from In the present invention,
The value obtained by dividing the total oxygen amount by the specific surface area is 0.20 to 0.40 m
g / m^TwoIt is necessary to be. [0007] The volatile component composition is a fixed amount of dry car
Pour Bon Black into a heat-resistant sample tube.^-2mmHg
After reducing the pressure to 1,500 ° C, it was installed in an electric furnace.
Then, volatile components were removed for 30 minutes. Collect this in the tank
After mixing, gas chromatography
Measure composition and amount_Two/ CO ratio (weight ratio) and
Calculate the total oxygen content / specific surface area. [0008] The specific surface area was measured by the BET method.
It is. That is, the low-temperature nitrogen adsorption device
1800 "(Italy, manufactured by Carlo Elba)
Measures the amount of nitrogen adsorbed on carbon black by the warm nitrogen adsorption method.
Was calculated by the multipoint method using the BET equation.
Things. Total oxygen determined from the volatile content at 1500 ° C
The amount is divided by the specific surface area and called the total oxygen amount per unit specific surface area
Attributes are specified for the following reasons. Generally, carbon black is acidified by various methods.
The oxygen functional groups increase as the specific surface area increases.
Is given. However, when compounded with resin, rubber, etc.
Physical properties are determined not by the absolute amount of oxygen functional groups but by the unit surface.
It correlates with the number of oxygen functional groups present. As a result of research, this attribute
Deeply involved in the dispersibility and zeta potential of liquid toner compositions
I found that. When the value of total oxygen content / specific surface area is 0.20 [mg
/ M^Two] Less than the amount when kneading the resin at high temperature
It is excellent in dispersibility, but in the next step of dispersing in a solvent,
Poor compatibility with the solvent results in a well-dispersed liquid toner
Not only cannot be obtained, but also the ratio of carbon black itself
Due to the low resistance, the specific resistance of the liquid toner tends to be low.
is there. The value of (total oxygen content / specific surface area) is 0.40.
[Mg / m^Two], Most of the carbon black surface
Is covered with an oxygen functional group, so the compatibility with the resin is poor,
A composition with a large amount of carbon black undispersed lumps results.
As a result, a liquid toner having a low print density is obtained. Carbo of the present invention
No matter what the production method, oil black
Furnace method, gas furnace method, acetylene exothermic decomposition method, etc.
Either is acceptable. As a production method by the oil furnace method,
Is, for example, a carbon black handbook (April 1, 1995)
5th, issued by Carbon Black Association of Japan) 278-285
The method described on the page can be used. Car with low PAH component
When manufacturing Bon Black, raise the temperature inside the production furnace.
Means such as prolonging the reaction time are used. Further, the total oxygen content / carbohydrate having a large specific surface area
To produce black, the carbohydrate produced from the production furnace
Air that reacts black black with air in a high-temperature atmosphere
Oxidation and nitrogen oxides at normal temperature, ozone, hydrogen peroxide, nitric acid, etc.
And can be achieved by reacting The resin of the present invention is preferably a thermoplastic resin.
Suitable. For example, vinyl chloride resin, vinylidene chloride
Resin, vinyl acetate resin, polyvinyl acetal resin,
Tylene resin, methacrylic resin, polyethylene tree
Fat, polypropylene resin, fluorine resin, polyamide
Resin, polyacetal resin, saturated polyester resin, etc.
But particularly preferably a carboxyl group or an ester
An olefin resin having a group, for example, ethylene
Vinyl acetate copolymer, ethylene-vinyl acetate copolymer
Partially saponified, ethylene / (meth) acrylic acid copolymer
Body, ethylene / (meth) acrylate copolymer,
(Meth) acrylic ester resin, styrene / (meth)
Acrylic acid copolymer, styrene / (meth) acrylic acid
And steal copolymers. One of these
Alternatively, two or more kinds can be used in combination. Further, the pigment composition for a liquid toner of the present invention
May contain a charge control agent and / or a dispersant. Electrification
As a control agent, conventionally used for controlling the charge of the developer
Such as nigrosine dyes, manganese naphthenate
, Calcium naphthenate, zirconium naphthenate,
Cobalt naphthenate, iron naphthenate, lead naphthenate, naphthenate
Nickel phthenate, chromium naphthenate, sodium naphthenate
Lead, magnesium naphthenate, manganese octylate,
Calcium octylate, zirconium octylate, octy
Iron luate, lead octylate, cobalt octylate, octyl
Chromic acid, zinc octylate, magnesium octylate,
Manganese dodecylate, calcium dodecylate, dodecyl
Zirconium, iron dodecylate, lead dodecylate, dodecyl
Cobalt luate, nickel dodecylate, chromatododecylate
Metals, zinc dodecylate, magnesium dodecylate, etc.
Soap, calcium dodecylbenzenesulfonate, dodeci
Sodium rubenzenesulfonate, dodecylbenzenes
Alkylbenzenesulfonates such as barium rufonate,
Lecithin, phospholipids such as seharin, n-decylamine, etc.
Organic amines, etc., alone or in combination of two or more.
Can be The amount of charge control agent added depends on the charge control effect.
The minimum amount that indicates
0.5 to 50% by weight, preferably 1 to 30% by weight
Is good. Next, as a dispersant used in the present invention, hydrophilic
Surfactants with ethylene oxide added as a group are preferred.
Suitable. Specifically, among anionic surfactants,
Higher alcohol ethylene classified as acid ester salt
Phosphate ester salts of oxide adducts and the like,
For nonionic surfactants, higher alcohol ethyl
Oxide adduct, alkylphenol ethylene oxide
Side adduct, fatty acid ethylene oxide adduct, polyvalent
Alcohol fatty acid ester ethylene oxide adduct,
Higher alkylamine ethylene oxide adducts, fatty acids
Amide ethylene oxide adducts, ethylene oxide of fats and oils
Side adduct, polypropylene glycol ethylene oxide
Side adducts, etc., alone or in combination of two or more.
Can be used. The amount of these dispersants added is usually
0.5 to 80% by weight based on the solid content of the liquid toner, preferably
The content is preferably 1 to 50% by weight. In the present invention, for example,
Knead carbon black and resin. When kneading,
It is preferable to grind the resin in advance to remove coarse particles.
is there. Resin and carbon black, preferably charge control
Mixing agent and / or dispersant, Henschel mixer,
Roller mixer, Nauta mixer, drum mixer,
After mixing using a tumbler, etc., the Banbury mixer
ー, kneader, two roll mill, three roll mill, one
It is kneaded by a screw extruder, a twin screw extruder or the like. Resin and car
The blending ratio of Bon Black is 50 to 99.9% by weight of the resin,
The pigment is preferably 50 to 0.1% by weight. The obtained kneaded material is preferably a frozen powder
Crushed. For example, cool sufficiently with dry ice or liquid nitrogen.
After cooling, or in an atmosphere with these refrigerants flowing,
Jet mill, Jet-O-Mizer, Counter
Using a wet mill and a super hammer mill.
It is frozen and pulverized to 0 μm or less, preferably 500 μm or less.
Also, after grinding, micron separator, turbo classif
With a classifier such as fire, micron classifier, etc.
By classifying to the desired particle size and removing coarse particles
It is preferable because the dissolution / dispersion efficiency of the next process can be further improved.
No. Next, it is dissolved and dispersed in a non-aqueous solvent. Non
Examples of the aqueous solvent include straight-chain or branched-chain fats.
Aromatic hydrocarbons, halogenated aliphatic hydrocarbons, aromatic hydrocarbons
Hydrogen, aliphatic alcohols, ethers and the like. Ingredient
Physically, non-aqueous solvents that do not dissolve resin
"ISOPAR G", "ISOPAR H", "A"
"Isopar K", "Isopar L", "Isopar M",
“Isoper V”, “Shellsol 7” manufactured by Shell Sekiyu KK
1, "IP1620" and "IP2" manufactured by Idemitsu Petrochemical Co., Ltd.
028 "," IP2835 "and the like. Also, resin
Non-aqueous solvents that dissolve benzene, toluene,
Methyl ethyl ketone, acetate, ethyl ether,
Tetrahydrofuran and the like are preferable, and these can be used alone or
Two or more can be used in combination. Dissolution during dispersion
The mixing ratio of the medium and the above-mentioned kneaded / crushed material is
The medium is added in an amount of 3 to 8 times by weight, preferably 4 to 7 times by weight.
It is good to scatter. In the dispersion, for example, the resin is dissolved.
And heated to 60-80 ° C to reduce viscosity.
Put the finely ground kneaded material in the medium and stir gently
It is preferably carried out after complete dissolution. As a dispersing machine
, Ball mill, pebble mill, attritor, sand
Grinders (vertical and horizontal) can be used.
Inomill "and" Cobra Mill "
Sand grinders are preferred. The temperature of the solution during dispersion depends on the type of resin and solvent.
It is usually preferably about 60 to 80 ° C. one
On the other hand, the dispersing time should be measured with a grind gauge or microscope every hour.
The dispersibility is tracked, and aggregates of 5 μm or more, preferably
Perform until there is substantially no aggregate of 3 μm or more.
Is good. Then, do not dissolve the resin in the resulting dispersion.
After adding an aqueous solvent to the desired carbon black concentration,
Method to precipitate carbon black and resin particles
Liquid toner. [0022] The present invention will be described in more detail with reference to the following examples.
Will be described. In the examples, parts are parts by weight, and% is% by weight.
Respectively. [Example 1] Carbon black is a conventional oil fur
Manufactured by the Loess method. However, as raw material oil, Na, C
a, Combustion using ethylene bottom oil with small S content
Used coke oven gas. Furthermore, as reaction stop water
Was manufactured using pure water treated with an ion exchange resin. [0023] 500 g of this CB is 50 cm in inner diameter and 1 in length.
Put into a 00cm cylindrical kiln and rotate at 25rpm
Air and NO_TwoGas mixture (NO_TwoConcentration 12000
ppm), A is 16 hours, B is 12 hours, C is 1 hour
Treatment was performed for 9 hours, D for 8 hours, and E for 24 hours. Next,
Put these carbon blacks separately in an external heat kiln and empty
Heat treatment at 200 ° C for 30 minutes while flowing air, and cool completely
A sample for evaluation after removal was obtained. [Example 1] Supermarket having a capacity of 20 liters
Mixer (Kawata "SMV-20") with ethylene
・ Partially saponified product of vinyl acetate copolymer “Dumilan C-2”
280 "(manufactured by Takeda Pharmaceutical Co., Ltd.) 2400g and carbon black
A (Table 1), 600 g, and nigrosine (Orient
30 g of "Bontron N-09" manufactured by Kagaku Co., Ltd.
8 "(Daiichi Kogyo Seiyaku Co., Ltd.) 300g, 2000r
Mix for 5 minutes at pm. The mixture is then brought to a maximum temperature of 15
Twin screw extruder set at 0 ° C (“TEM-3 manufactured by Toshiba Machine Co., Ltd.”
5B "), and after kneading, about 1-2 mm diameter with a strand cutter
To obtain a kneaded pellet. Next, the pellet is immersed in liquid nitrogen and cooled sufficiently.
After the rejection, a jet mill (“STJ-20” manufactured by Seishin Enterprise Co., Ltd.)
0 "). The ground product was set at 70 ° C
It dried for 10 hours with a vacuum dryer. Also, the average grain of the crushed product
The diameter was 120 μm. Then, "Isoper G"
48% (manufactured by Esso Oil), toluene (manufactured by Katayama Chemical)
32%, 20% ethanol (Katayama Chemical Co., Ltd.) mixed solution
2550 g and 450 g of the above crushed product in a stainless steel container
And gradually increase the temperature while stirring at 100 rpm.
Then, the mixture was dissolved at 70 ° C. for 30 minutes. Then, the melt was kneaded to a volume of 1.4 liters.
"Dino Mill" (Shinmaru Enterprises, Inc.)
3.5 sold 70 ℃ solution to KDL-pilot type)
It flowed in at a rate of liter / min and dispersed for 3 hours.
A part of the dispersion liquid is thinly applied to a glass plate, and an optical microscope 400
As a result of observing the dispersibility at 2 times, there was no aggregate of 1 μm or more.
there were. Next, a stirrer, a thermometer and a reflux condenser are provided.
In a container, 2.0 parts of the dispersion and 150 parts of the mixed solvent
Part, “MRB-8” 0.24 part, “Dumilan C-22”
80 ”and stirred at 70 ° C. for 30 minutes.
After completely dissolving "Milan C-2280", 30
It was allowed to cool to ℃ to precipitate pigment resin particles. This pigment tree
Replace the mixed solvent of the fat particle dispersion with “Isopar G”,
Positive charge by adding zirconium naphthenate as charge control agent
Liquid toner. Evaluation of Physical Properties and Image Quality of Liquid Toner
The results are shown in Table 1. The toner particle size was measured by Horiba, Ltd.
The diffraction / scattering particle size distribution analyzer LA-700, zeta potential is
Otsuka Electronics Co., Ltd. Laser Zeta Electrometer "LEZA-6"
00 ". Evaluation of toner particle dispersibility
Measure the viscosity of 10% particle concentration toner with a B-type viscometer
(Rotor rotation speed 6 rpm). The image quality is "Mitsubishi Electronic Printing
Printed on coated paper using the
Valued. Image density was measured using a Macbeth densitometer. [Embodiment 2] and [Embodiment 3] Instead of the carbon black of Example 1, B and C of Table 1
All in the same manner as in Example 1 except that carbon black was used.
Was carried out. The evaluation results of physical properties and image quality are shown in Table 2.
It is on the street. Instead of carbon black of Example 1,
Performed all except using carbon black of D and E of 1.
It carried out similarly to Example 1. Evaluation results of physical properties and image quality
It is as shown in Table 2. [0030] [Table 1] [0031] [Table 2][0032] According to the present invention, an image having a sufficient print density can be obtained.
Obtain a pigment composition for a liquid toner capable of obtaining characteristics
be able to.

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasuharu Suda 4-6-22 Kanon Shinmachi, Nishi-ku, Hiroshima City Inside the Hiroshima Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Hiroaki Kuno 4-2-2 Kannon Shinmachi, Nishi-ku, Hiroshima City No. Mitsuishi Heavy Industries, Ltd. Hiroshima Laboratory (56) References JP-A 8-320589 (JP, A) JP-A 4-181514 (JP, A) JP-A 5-178604 (JP, A) JP 9-286938 (JP, A) JP-A-9-165512 (JP, A) JP-A-10-17808 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 9/12 G03G 9/08 C09C 1/48

Claims (1)

(57) [Claim 1] Carbon black and a resin are dissolved and dispersed in a non-aqueous solvent.
A pigment composition for a liquid toner, comprising carbon black having a value obtained by dividing the total amount of oxygen determined by the volatile composition at 500 ° C. by the specific surface area to be 0.20 to 0.40 mg / m ² .