JPH10186734A - Liquid developer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of an image run on a transfer body to enhance the printing density in a liquid developer in which a toner grain containing at least a binder resin and a coloring agent is dispersed in a dispersing medium, SOLUTION: In a liquid developer in which a toner grain containing at least a binder resin and a coloring agent is dispersed in a dispersing medium, AC conductivity IA, toner charge Q/M per unit weight, and weight average grain size DV satisfy IA>5 (pS/cm), Q/M>30 (μC/g), and 0.1<DV<5 (μm), respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid developer used in an image forming method for developing an electrostatic latent image on an electrostatic latent image carrier with a liquid developer. The present invention relates to a developer used in an image forming method used for a printer.

[0002]

2. Description of the Related Art A latent image formed on an electrostatic latent image carrier such as a photoreceptor can be developed using fine toner particles dispersed in a carrier solvent. A solvent in which such toner particles are dispersed is known as a liquid toner or a liquid developer. A liquid developer can make toner particles finer than a dry developer, so that a higher definition image can be formed. The toner particles are generally composed of a resin component as a binder and a pigment or dye as a colorant. As the resin component, a thermoplastic resin is often used. As the colorant, a pigment excellent in light resistance, solvent resistance and the like is often used.

As a carrier solvent, a non-polar solvent having a high volume resistivity of generally 10 ⁹ ohm-cm or more and a low dielectric constant of less than 3.0 is used. Examples of such a liquid developer include, for example, JP-A-5-50694.
1 and the like are known.

Using such a liquid developer, an electrostatic latent image on an electrostatic latent image carrier is developed, and a developed image (an image formed by toner) developed by the development is transferred. When transferred to the body, there is a problem that an image flow in which a visual image flows in the process direction is likely to occur. In particular, when the print density is increased, this phenomenon occurs when a small particle size toner is used to obtain a high-definition image. Since such an image flow significantly lowers the image quality of a printed matter, a developer which does not cause the image flow used in the above-described image forming method has been desired.

[0005]

The following items are required for the liquid developer used in the above-described image forming method.

(1) No image flow occurs on the transfer object.

(2) The print density on the transfer medium is high.

(3) A high-definition image can be formed.

The present invention has been made by studying a developer satisfying such conditions, and an object of the present invention is to provide a liquid developer satisfying the above conditions.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
In the liquid developer formed by dispersing toner particles containing at least a binder resin and a colorant in a dispersion medium, 1) an AC conductivity I _A is _{I A> 5 (pS / cm} ) 2) Toner charge per unit weight Q / M> Q / M> 20 (μC / g) 3) It is achieved by the liquid developer, wherein the weight average particle diameter Dw of the toner particles satisfies all of 0.1 <Dw <5 (μm). You.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

The liquid developer of the present invention is obtained by dispersing 0.1 to 20% by weight of toner particles mainly containing a pigment, a dye and a resin in an insulating non-polar solvent. Preferably, it is 0.5 to 5% by weight. When the developer concentration is less than 0.1% by weight, it is difficult to obtain a sufficient print density. On the other hand, if the developer concentration exceeds 20% by weight, it becomes difficult to electrically and physically remove the toner image on the white background, so that white background staining occurs.

The toner particles are mainly composed of a pigment or a dye and a resin, but are preferably toner particles in which a pigment having excellent light resistance and solvent resistance is dispersed in a resin. The proportion of the pigment in the particles is preferably from 5% by weight to 30% by weight. More preferably, the content is 10% by weight or more and 25% by weight or less. When the proportion of the pigment is less than 5% by weight, the coloring power of the toner is low and the print density is low. On the other hand, when the proportion of the pigment exceeds 30% by weight, the fixability is deteriorated and the gloss is reduced because the proportion of the binder resin is low.

The average particle diameter D _W of the toner particles of the present invention is
Preferably, it is larger than 0.1 μm and smaller than 5 μm. More preferably, it is larger than 0.1 μm and smaller than 1.5 μm.

If the weight average particle diameter is 0.1 μm or less, white background stains are liable to occur due to unstable fine particles. When the weight average particle size is 5 μm or more, image roughness occurs and high resolution cannot be obtained. Here, the weight average particle size of the toner particles is SHIMADZU SA-CP3.
It was measured by a centrifugal particle size analyzer. in this case,
The liquid toner is diluted with a dispersion medium so as to match the absorbance measurement range of the measuring instrument, and this sample is subjected to 2400 RPM /
The particle distribution was measured from the change in absorbance in the acceleration rotation mode for one minute. The weight average particle diameter was calculated by the median diameter.

As described above, when a visible image (image formed by toner) is formed on an electrostatic latent image carrier using such a liquid developer and transferred to a transfer-receiving member, the visible image is There is a problem that an image flow flowing in the process direction is likely to occur. In particular, this phenomenon is more likely to occur when the print density is increased or when a small particle size toner is used. One of the causes of image deletion is that when the developed image is transferred onto the transfer target, the physical transfer between the electrostatic latent image carrier and the transfer target occurs because the visible image contains a carrier solvent and the packing is poor. May be disturbed.

In order to prevent such image deletion, the amount of electric charge Q of the toner particles is increased to increase the force F (= QE) applied to the toner particles in the electric field (E), thereby reducing the electrostatic charge. The packing of the toner image on the latent image carrier may be strengthened, and the amount of the carrier solvent on the electrostatic latent image carrier may be reduced. There is a possibility that the transfer rate from the carrier to the transfer target may be deteriorated.

In the present invention therefore, it was carried out an extensive study about conditions to strengthen the packing of the toner image on the electrostatic latent image bearing member, the alternating conductivity I _A is 5 (pS / cm)
And the toner charge Q / M per unit weight is 20
When ([mu] C / g) exceed, preferably, I _A is 10 (p
S / cm) and the toner charge Q /
When M exceeds 50 (μC / g), the small particle size toner (0.
It has been found that even when 1 <D _W <5) is used, no image deletion occurs. Also, when I _A is less than 5, it may issue a high printing density for the toner developability is poor difficult. Even AC conductivity when I _A is greater than 5, when Q / M is less than 20, less charge the toner particles have an electric field force applied to the toner particles in (E) F (= QE) Is weak, the packing of the toner image on the electrostatic latent image carrier becomes poor, and an image flow occurs.

The AC conductivity I _A is 1.5 wt% of the toner developing solution CONDUCTIVITY METER MODEL627 (Scientifica, Inc.)
Measure using Further, the value obtained as follows is used as the value of Q / M. 1.4 g of a 1.5 wt% liquid toner is put into a liquid cell LP-5 (manufactured by Kawaguchi Electric Co., Ltd.), and HI
A (current)-(time) curve (FIG. 1) is obtained by applying a voltage of 1000 V for 1.5 minutes using GH MEGOHM METER TR 8601 (Takeda Riken: currently manufactured by Advantest). Further, the sum of the weights of all the toner particles is determined by measuring the weight of the solid content in the electrode adhesion component. The solid content weight M of the electrode attachment component is determined by the following equation.

M = (dried at 120 ° C. for 1.5 hours,
The electrode weight after voltage application) − (electrode weight before voltage application) Then, assuming that the area of the hatched portion in FIG. 1 is the sum Q of the charges of all the toner particles included in the sample, Q / M is obtained from Expression 1.
Is calculated.

[0021]

(Equation 1) Note that, in the above measurement, the voltage application time to the electrode of the liquid cell was 1.5 minutes, but if the current flowing through the electrode after a lapse of 1.5 minutes after applying the voltage is a value that cannot be ignored,
The above-described measurement is performed while voltage application is continued until time t when the value becomes negligible. Here, the time t at which the current flowing through the electrode becomes a negligible value is the area S of the hatched portion in FIG. 1 and the time t + 30 in the case where the voltage is continuously applied until the time t.
Difference from the area S ′ of the hatched portion in FIG. 1 in seconds ΔS = S ′
-Defined by the time t at which S becomes 1/100 of S.

When the concentration of the liquid developer is different from 1.5 wt%, the concentration is adjusted to 1.5 wt% by means such as dilution with a dispersion medium or concentration of the liquid developer. And As the carrier solvent (insulating non-polar solvent) used in the liquid developer of the present invention, for example, n-hexane, n-heptane, n-octane, n-nonane, n
-Decane, n-undecane, n-dodecane, n-tridecane, n-tetradecane, n-pentadecane, n-hexadecane, n-heptadecane, 2-methyloctane, 2
Petroleum aliphatic hydrocarbons such as -methylnonane, 2-methyldecane, 2-methylundecane, 2-methyldodecane, ligroin, and mixtures thereof ("Christol" 52, 352 manufactured by Esso Oil Co., Ltd., JWS 894 as a commercial product)
7, "Norpearl" 12, 13 manufactured by Exxon Chemical Co., Ltd., "Isopar" E, G, H, L, M, ", Shell Sol 71 manufactured by Shell Sekiyu, Solvesso 150, etc.) are used.

Examples of the resin include alkyd resin, styrene resin, phenol resin, acrylic resin, styrene-acryl resin, polyester resin, ethylene-vinyl acetate resin, methacryl resin, epoxy resin, amide resin, carbonate resin, rosin-modified maleic acid Resins, rosin-modified phenolic resins and the like can be mentioned, and it is preferable to use rosin-modified maleic resin having good pigment dispersibility.

As pigments and dyes, general ones are used. If the pigment is a black pigment, carbon black (for commercial products, for example, # 30, # 40, # 50, MA-1 manufactured by Mitsubishi Chemical Corporation) is used.
1, MA-100, MONARCH70 manufactured by Cabot Corporation
0,900, REGAL300,400,600R, M
ogul-1) can be mixed with carbon black.

In the case of yellow, fast yellow, disazo yellow, tartrazine yellow, condensed azo yellow, quinoline yellow, thioflavin lake, flavantron yellow, isoindolinone yellow, quinophthalone yellow, isoindoline yellow, nickel nitroso yellow, copper Azomethine yellow, toluidine red, pyrazolone red, lake red if reddish,
Phloxine lake, condensed azo red, rhodamine lake, dianthraquinolyl red, thioindigo bordeaux, verinone red, berylen scarlet, quinacridone red, isoindolinone red, madder lake,
For indigo, dianisidine blue, phthalocyanine blue, Beacock Blue Lake, Victoria Pure Blue, Indanthrone Blue, alkali blue, phthalocyanine green, oil violet, methyl orange, methyl violet and the like are used.

The toner particles are mainly composed of a pigment and a resin, but polyethylene glycol, polypropylene glycol or the like may be added for adjusting the softening point.

Furthermore, a charge control agent may be added to the surface of the particles for controlling the charge. The toner particles contained in the present liquid developer can be positively or negatively charged by appropriately selecting a charge control agent. The charge control agent is not particularly limited, for example, low molecular weight lecithin, barium petronate, sodium alkyl succinate, cobalt naphate, aluminum stearate, cobalt octate, zirconium naphthate,
In addition to quaternary ammonium salts, tertiary amines, and the like, a polymeric charge control agent can be used. The content of the charge control agent in the developer is not particularly limited.
It is contained in an amount of about 01-5% by weight.

Since the polymer type charge control agent can function not only as a charge control function but also as a dispersant, it is possible to improve not only the developing characteristics of the developer but also the storage characteristics. By using an appropriate amount thereof, the toner particles are provided with a sufficient charge, the dispersibility of the toner particles in the developer is improved, and the aggregation of the toner particles during long-term storage or high-temperature storage is suppressed. Examples of the polymer-type charge control agent include polyacryl methacrylate, polyhydroxy compounds, polycarboxylic acids, polycarboxylic esters, polyamides, polyhydroxycarboxylic acids, and polyhydroxycarboxylic esters. A graft-type amphiphilic polymer having a site having good compatibility with each resin is preferable because the charge is stable. Examples of the portion soluble in the carrier solvent include, for example, higher fatty acid vinyl ester, vinyl alkyl ether, alkyl acrylate,
Polymers polymerized from alkyl methacrylate and the like can be mentioned. Further, as a portion soluble in the resin, for example, vinyl acetate, vinyl chloride, methacrylic acid,
Examples include, but are not limited to, polymers polymerized from methyl acrylate, methyl methacrylate, acrylonitrile, dialkylaminoalkyl acrylate, and the like. In addition, as examples of such amphiphilic polymers, those shown on page 2, line 3 to page 3, line 6 of JP-B-60-15063 are known.

When the above-mentioned polymer type charge control agent is used not only as a charge control agent but also as a dispersant, an appropriate amount differs from that of a normal charge control agent. As a result of intensive studies on the appropriate amount, 0.1 to 3 parts by weight, more preferably 0.1 to 1 part by weight, of the polymer type charge control agent per 1 part by weight of the toner particles was determined. It was found that when was included, the dispersion characteristics could be improved without impairing the development characteristics.

When the amount of the polymeric charge control agent is 0.1 parts by weight or less, sufficient dispersibility cannot be obtained due to the low concentration of the polymeric charge control agent around the toner particles. In some cases, toner particles may aggregate. Further, when the amount of the polymer type charge control agent is 3 parts by weight or more, the amount of the dispersant in the toner image after development becomes too large, the packing of the toner image becomes poor, and the image may flow.

When the polymer type charge control agent is used as a dispersant as described above, the above-described charge control agent may be used in order to balance the charge characteristics and the dispersion characteristics of the toner particles.

Further, wax may be added for improving dispersibility. Examples of the wax include synthetic waxes such as polyethylene wax and polypropylene wax, and natural waxes such as montan wax and carnauba wax. The content of the wax in the developer is not particularly limited, but is usually 0.001 to 10% by weight.

In the preparation of the liquid developer of the present invention, the resin and the colorant are melt-kneaded by applying heat with a twin-screw extruder, a kneader or the like, and after coarsely pulverized, a charge control agent,
The dispersing is preferably performed by using a ball mill, a vibration mill, an attritor or the like in an insulating non-polar solvent together with an additive such as a wax, but the method is not limited to this method.

Next, the image forming method of the present invention will be described.

The toner of the present invention is used for developing an electrostatic latent image on an electrostatic latent image carrier to visualize the toner. Paper, selenium-based photoconductors, organic photoconductors, amorphous silicon photoconductors, and the like. When a photoreceptor is used as the electrostatic latent image carrier, a visualized image on the photoreceptor that has been visualized by development is transferred to a transfer target such as paper and fixed. When a multicolor image is formed using a multicolor toner, for example, the electrostatic latent image on the electrostatic latent image carrier is developed with a liquid toner, and the visualized image visualized by this development is developed. A multicolor image is formed on the transfer object by repeating a process of electrostatic transfer to the transfer object,
There is a method of fixing an image finally formed on a transfer medium.

The transfer material referred to in the present invention includes:
Any kind of paper, plastic film, metal, cloth, board, etc. can be used as long as it can be printed normally.

Further, when developing the electrostatic latent image, an image forming method in which a liquid developer is supplied to the electrostatic latent image on the electrostatic latent image carrier through a developing roller to develop the electrostatic latent image is preferable.

These image forming methods are used, for example, in copying machines and laser beam printers.

[0039]

EXAMPLES Next, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 1400 g of rosin-modified maleic resin (FGM310, acid value 100, softening point 120 ° C., manufactured by Arakawa Chemical Co., Ltd.), 400 g of Lionol red 6B FG4213 (manufactured by Toyo Ink Co., Ltd.), polyethylene glycol (PEG6)
2,000, manufactured by Sanyo Kasei Co., Ltd.) was premixed with a mixer, and then melt-kneaded using a twin-screw extruder.
(Amount: 2 kg / hr, temperature: 100 ° C.). After cooling the obtained melt-kneaded material, a particle size of about 50 μ
m of coarse powder. 200 g of this coarse powder and 1000 g of an acrylic polymer type charge control agent solution (US Pat. No. 3,900,
No. 412, column 24, lines 20-36, the procedure described in Example XI, ie "400 g of petroleum ether is placed in a 1 liter flask and gently refluxed with stirring. A mixed solution of 194 g of methacrylate, 6 g of glycidyl methacrylate, and 3 g of benzoyl peroxide was added dropwise over 3 hours using a dropping funnel, and after refluxing for 40 minutes, 0.5 g of lauryl dimethylamine was added.
Reflux for hours. Hydroquinone 0.1 g, methacrylic acid 3.0 g
And refluxed under a nitrogen atmosphere to esterify about 25% of the glycidyl groups to obtain a precursor polymer solution. Next, after mixing 27.5 g of the precursor polymer solution, 30 g of methyl methacrylate, 0.5 g of methacrylic acid, 0.4 g of AZBN, 134 g of petroleum ether, and 29.5 g of Isopar G, the mixture is gently refluxed for 20 minutes. 1.4 g of Isopar K solution (10% solution) of n-octyl mercaptan is added to the above solution. After stirring the obtained solution for 2.5 hours or more, gently reflux for 1.5 hours and return to room temperature to obtain the desired polymer solution. , 14 g of solid content), 15 g of montan wax, and 400 g of JWS 8947 (manufactured by Esso Oil Co., Ltd.), and pulverized by a vibration mill for 7 hours to obtain a liquid toner. This stock solution was adjusted to JWS89 so that the solid content concentration became 3%.
47 (manufactured by Esso Oil Co., Ltd.) to obtain a developer. The average particle size D _W of the toner in this developer was 0.7 μm. Further, the AC conductivity I _A of the developer 35 (pS
/ Cm), and the charge amount per unit weight Q / M is 60
(ΜC / g).

The liquid developer obtained as described above is developed on an organic photoreceptor, an image is electrostatically transferred onto art paper supported on a transfer drum, and the image is heated at a temperature of a pressure roller. Was 200 ° C., and a good printed matter without image deletion was obtained.

Example 2 1400 g of rosin-modified maleic resin (FGM310, acid value 100, softening point 120 ° C., manufactured by Arakawa Chemical Co., Ltd.), 400 g of KET YELLOW405 (manufactured by Dainippon Ink and Chemicals, Inc.), polyethylene glycol 200 g (PEG 6000, manufactured by Sanyo Kasei Co., Ltd.) was preliminarily mixed with a mixer, and then melt-kneaded using a twin-screw extruder (feed amount 2 kg / hr, temperature 100 ° C.). After cooling the obtained melt-kneaded material, a coarse powder having a particle size of about 50 μm was obtained using a sample mill. 200 g of the coarse powder and 1000 g of an acrylic polymer type charge control agent solution (U.S. Pat. No. 3,900,412, column 24, lines 20 to 36,
Made by the method described in Example XI, solids 14
%) 15 g of carnauba wax and 400 g of JWS 8947 (manufactured by Esso Oil Co., Ltd.) were mixed and pulverized with a vibration mill for 7 hours to obtain a toner stock solution.

This stock solution was diluted to a solid concentration of 3% to prepare a developer. The average particle size D _W of the toner in this developer was 0.8 μm. Further, the AC conductivity I _A of the developer is 29 (pS / cm), the charge amount Q / M per unit weight was 70 (μC / g).

When the same evaluation as in Example 1 was performed using this developer, a good printed matter free of image deletion could be obtained.

Example 3 1400 g of rosin-modified maleic resin (FGM310, acid value 100, softening point 120 ° C., manufactured by Arakawa Chemical Co., Ltd.), 400 g of KET YELLOW405 (manufactured by Dainippon Ink and Chemicals, Inc.), polyethylene glycol- 200 g (PEG 6000, manufactured by Sanyo Kasei Co., Ltd.) was preliminarily mixed with a mixer, and then melt-kneaded using a twin-screw extruder (feed amount 2 kg / hr, temperature 100 ° C.). After cooling the obtained melt-kneaded material, a coarse powder having a particle size of about 50 μm was obtained using a sample mill. 200 g of this coarse powder and 110 g of an acrylic polymer type charge control agent solution (US Pat.
No. 900,412, column 24, lines 20-36, produced by the method described in Example XI, solid content 14
%), 15 g of carnauba wax and 1250 g of JWS 8947 (manufactured by Esso Sekiyu KK) were mixed and pulverized with a vibration mill for 7 hours to obtain a stock toner solution.

50 g of this stock solution, 50 g of an acrylic polymer type charge control agent solution, JWS8947 (manufactured by Esso Oil Co., Ltd.)
A developer was prepared from 250 g. The average particle size D _W of the toner in this developer was 0.8 μm. Further, the AC conductivity I _A of the developer is 31 (pS / cm),
The charge Q / M per unit weight was 67 (μC / g).

When the same evaluation as in Example 1 was performed using this developer, a good printed matter free of image deletion could be obtained.

Example 4 As a coloring agent, Finess Yello
w G-20 S-2 (Toyo Ink Co., Ltd .: yellow pigment), Li
Same as Example 1 using onol red 6B FG4213 (manufactured by Toyo Ink Co., Ltd .: magenta pigment), Lionol Blue SM (manufactured by Toyo Ink Co., Ltd .: cyan pigment), and Mogul-l (manufactured by Cabot Corporation: black pigment) Using the above method, four kinds of liquid developers (solid content was 3%) were prepared.

[0049] These yellow, magenta, cyan, alternating conductivity I _A Each of the black liquid developer "30,
35, 31, 28 (pS / cm), and the charge Q / M per unit weight of the toner particles is 63, 60, 67, 7
3 (μC / g).

The weight average particle diameter D _W of the toner particles was 0.9, 0.7, 0.8, 1.3 (μm).

Next, a process of developing the liquid developer on an organic photoreceptor and electrostatically transferring an image onto art paper supported on a transfer drum is performed in the order of cyan, magenta, yellow, and black. After forming a multicolor image on art paper, the multicolor image is
When the image was fixed under the condition of 0 ° C., a good printed matter without image deletion could be obtained.

Example 5 Ket Yellow 4 was used as a colorant.
05 (manufactured by Dainippon Ink and Chemicals, Inc .: yellow pigment), lionol red 6B FG4213 (manufactured by Toyo Ink Co., Ltd .: magenta pigment), No. 700-10S Cyanine Blue (manufactured by Toyo Ink Co., Ltd .: cyan pigment) , Mogul-l (Cabot Corporation:
Using a black pigment), four types of liquid developers (solid content was 3%) were prepared in the same manner as in Example 1.

[0053] These yellow, magenta, cyan, AC conductivity I _A black liquid developer, respectively 29,3
5, 30, 28 (pS / cm), and the charge amount Q / M per unit weight of the toner particles is 70, 60, 67, 73.
(ΜC / g).

The weight average particle diameter D _W of the toner particles was 0.8, 0.7, 0.7, 1.3 (μm).

Next, a process of developing the liquid developer on an organic photoreceptor and electrostatically transferring an image onto art paper supported on a transfer drum is performed in the order of cyan, magenta, yellow, and black. After forming a multicolor image on art paper, the multicolor image is
When the image was fixed under the condition of 0 ° C., a good printed matter without image deletion could be obtained.

Example 6 Ket Yellow 40 was used as a colorant.
5 (Yellow pigment, manufactured by Dainippon Ink and Chemicals, Inc.), K
et Red 309 (manufactured by Dainippon Ink and Chemicals, Inc .: magenta pigment), No. 700-10S Cyanine Blue (Toyo Ink Co., Ltd.)
Four kinds of liquid developers (solid content: 3%) were prepared by using the same method as in Example 1 by using the same method as that of Example 1 using Cog (manufactured by Cyan Pigment) and Mogul-1 (Cabbot: black pigment).

[0057] These yellow, magenta, cyan, AC conductivity I _A black liquid developer, respectively 29,4
0, 30, and 28 (pS / cm), and the amount of charge Q / M per unit weight of the toner particles is 70, 73, 67, and 73.
(ΜC / g).

The weight average particle diameter D _W of the toner particles was 0.8, 1.0, 0.7, 1.3 (μm).

Next, a process of developing the liquid developer on an organic photoreceptor and electrostatically transferring an image onto art paper supported on a transfer drum is performed in the order of cyan, magenta, yellow, and black. After forming a multicolor image on art paper, the multicolor image is
When the image was fixed under the condition of 0 ° C., a good printed matter without image deletion could be obtained.

Comparative Example 1 1400 g of rosin-modified maleic resin (FGM310, acid value 100, softening point 120 ° C., manufactured by Arakawa Chemical Co., Ltd.), 400 g of Lionol red 6B FG4213 (manufactured by Toyo Ink Co., Ltd.), polyethylene glycol (PEG6)
After 200 g of 2,000 (manufactured by Sanyo Chemical Co., Ltd.) was preliminarily mixed by a mixer, the mixture was melt-kneaded using a twin-screw extruder (feed amount: 2 kg / hr, temperature: 100 ° C.). After cooling the obtained melt-kneaded material, a coarse powder having a particle size of about 50 μm was obtained using a sample mill. 200 g of this coarse powder and 110 g of an acrylic polymer type charge control agent solution (US Pat. No. 3,900,412)
No., column 24, lines 20 to 36, prepared by the method described in Example XI, solid content: 14%), montan wax 20 g, JWS8947 (manufactured by Esso Oil) 125
And 0 g, and crushed for 7 hours with an attritor to obtain a liquid toner stock solution. This stock solution was diluted with JWS8947 (manufactured by Esso Petroleum Corporation) so as to have a solid content concentration of 2% to obtain a developer. The average particle diameter D _W of the toner in this developer is 1.
0 microns. Also, the AC conductivity I of this developer is
_A was 4.9 (pS / cm), and the charge per unit weight Q / M was 14 (μC / g).

When the same evaluation as in Example 1 was performed using this developer, an image deletion occurred.

Comparative Example 2 1400 g of rosin-modified maleic resin (FGM310, acid value 100, softening point 120 ° C., manufactured by Arakawa Chemical Co., Ltd.), 400 g of Lionol red 6B FG4213 (manufactured by Toyo Ink Co., Ltd.), polyethylene glycol (PEG6)
After 200 g of 2,000 (manufactured by Sanyo Chemical Co., Ltd.) was preliminarily mixed by a mixer, the mixture was melt-kneaded using a twin-screw extruder (feed amount: 2 kg / hr, temperature: 100 ° C.). After cooling the obtained melt-kneaded material, a coarse powder having a particle size of about 50 μm was obtained using a sample mill. 200 g of this coarse powder and 10 g of an acrylic polymer type charge control agent solution (US Pat. No. 3,900,412)
No. 24, lines 20-36, prepared by the method described in Example XI, solid content 14%), lecithin
0g (solid content 14%), montan wax 15g, JW
S8947 (manufactured by Esso Oil Co., Ltd.)
The mixture was pulverized with an attritor for 7 hours to obtain a liquid toner stock solution. The undiluted solution is adjusted to JWS89 so that the solid concentration becomes 2%.
47 (manufactured by Esso Oil Co., Ltd.) to obtain a developer. The average particle size D _W of the toner in this developer was 1.4 μm. Further, the AC conductivity I _A of the developer 56 (pS
/ Cm), and the amount of charge Q / M per unit weight is
0.7 (μC / g).

When the same evaluation as in Example 1 was performed using this developer, an image deletion occurred.

[0064]

As described above, the liquid toner of the present invention is used.
By using a liquid developer, it is possible to obtain a liquid developer that satisfies no image deletion and high print density.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for calculating a sum of charges of all toner particles included in a sample.

Claims (4)

[Claims] 1. A least in binder resin and a colorant and a liquid developer obtained by dispersing toner particles containing a dispersion medium, 1) an AC conductivity I _A is _{I A> 5 (pS / cm} ) 2) units A liquid developer, wherein the toner charge per weight Q / M is Q / M> 20 (μC / g) 3) The weight average particle diameter Dw satisfies all of 0.1 <Dw <5 (μm). 2. A liquid developer in which toner particles containing at least a binder resin and a colorant are dispersed in a dispersion medium, wherein 0.1 to 3 parts by weight of a polymer is added to 1 part by weight of the toner particles. The liquid developer according to claim 1, further comprising a mold charge control agent. 3. A liquid developer in which toner particles containing at least a binder resin and a colorant and a polymeric charge control agent are dispersed in a dispersion medium, wherein the polymeric charge control agent is an amphiphilic polymer. 3. The liquid developer according to claim 2, wherein the liquid developer is provided. 4. A process for developing an electrostatic latent image on an electrostatic latent image carrier by using a liquid toner and repeating a process of electrostatically transferring a developed image visualized by the development to a transfer target. 4. The liquid developer according to claim 1, which is used in a process for forming a multicolor image on a body.