JPH10186733A - Liquid toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrostatic charge-image-developing liquid toner, which can improve "k-, developing density and provide a good-resolution image that is free of flowing and crushing, and in which toner particles composed chiefly of a resin and a coloring agent are dispersed in the carrier liquid of petroleum aliphatic hydrocarbon, by making the liquid toner contain a specific amount of water in relation to nonvolatile components. SOLUTION: An electrostatic charge-image-developing liquid toner, in which toner particles A composed chiefly of a resin and a coloring agent are dispersed in the carrier liquid of petroleum aliphatic hydrocarbon, contains not less than 0.1wt.% to not more than 3.0wt.% water in relation to nonvolatile components. The carrier liquid used in the liquid toner is preferably a petroleum aliphatic hydrocarbon solvent. The toner particles are composed chiefly of a resin and a pigment or dye, and are desirably colored particles in which the pigment is dispersed in the resin. The rate of the pigment in the particles is desirably not less than 5wt.% to not more than 30wt.%. Desirably, the resin has an acid number of not less than 20 to not more than 250.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid toner used in an image forming method for developing an electrostatic image on an electrostatic image carrier with a liquid toner, for example, a copying machine or a laser beam. The present invention relates to a liquid toner used in an image forming method used in a printer.

[0002]

2. Description of the Related Art As a liquid toner used in a wet electrophotographic image forming method such as a wet electrophotographic printer, resin and colored toner are disclosed as representatively disclosed in Japanese Patent Application Laid-Open No. 5-506941. A toner in which toner particles containing an agent as a main component are dispersed in a carrier liquid composed of a petroleum-based aliphatic hydrocarbon solvent is used. The toner particles are given a charge by a coexisting dispersant or charge control agent, so that the toner particles can be developed with respect to an electrostatic image.

[0003] In order to achieve improved image quality, high development densities are desirable properties. For this purpose, attempts have been made to increase the amount of charge of the toner particles by adjusting the dispersant and the charge control agent. On the other hand, however, increasing the charge amount of the toner particles reduces the cohesion between the particles due to electrostatic repulsion between the toner particles, and removes the liquid from the developed toner image or transfers the liquid to the transfer material. In the process, there is a problem that the flow of the image and the collapse of the image easily occur.

[0004]

[Problems to be Solved by the Invention] Published Patent Publication 5-5
When the liquid toner described in No. 06941 is used in a wet electrophotographic printer, under the condition that a sufficient development density can be obtained, it is difficult to obtain an image of good quality due to the thinned lines being thickened and the dots flowing. was there.

An object of the present invention is to provide a liquid toner capable of improving the development density and obtaining an image of good resolution without running or collapsing.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
In a liquid toner for developing an electrostatic image formed by dispersing toner particles containing a resin and a colorant as main components in a carrier liquid of a petroleum aliphatic hydrocarbon, the liquid toner is 0.1% by weight with respect to a nonvolatile component. % By weight, and at least 3.0% by weight of water.

[0007]

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

The liquid toner according to the present invention is a liquid toner for developing an electrostatic image, comprising toner particles containing a resin and a colorant as main components dispersed in a carrier liquid of petroleum aliphatic hydrocarbon. 0.1% by weight based on the nonvolatile content
A liquid toner containing at least 3.0% by weight of water.

The carrier liquid used in the liquid toner is preferably a petroleum aliphatic hydrocarbon solvent, for example, n-hexane, n-heptane, n-octane, n-nonane, isooctane, indodecane, ligroin and mixtures thereof. Petroleum aliphatic hydrocarbons ("Isoper" E, G, H, L, M, "Cristol" 52, 352 manufactured by Exxon Chemical Co., Ltd .; "Shersol" 71, "Solvesso" manufactured by Shell Chemical Co., Ltd.) 150 etc.) are used.

The toner particles contain a resin and a pigment or a dye as main components, and are preferably colored particles in which the pigment is dispersed in the resin. 5% by weight pigment in particles
It is preferably at least 30% by weight. More preferably, the content is 10% by weight or more and 25% by weight or less. 5% by weight pigment
If it is smaller, it is difficult to obtain the print density,
When the content is more than the weight percentage, the pigment is not completely bound by the resin, and a problem such as white background stain is likely to occur.

As the resin, a resin having an acid value of 20 or more and 250 or less is preferable. More preferably, it is 50 or more and 200 or less, and still more preferably 70 or more and 150 or less. If the acid value of the resin is less than 20, the chargeability becomes poor and 2
If it exceeds 50, dispersibility in the carrier liquid becomes poor.

The softening point of the resin is 70.degree.
It is preferable that the temperature is not higher than ° C. If the softening point is lower than 70 ° C., the storage stability becomes poor, and if it exceeds 150 ° C., the fixing performance becomes poor.

Specific examples of the above resin include alkyd resin, styrene resin, phenol resin, acrylic resin,
Styrene-acrylic resin, polyester resin. A rosin-modified phenol resin, a rosin-modified maleic resin, a rosin-modified fumaric acid resin, and the like. Preferably, it is a rosin-modified maleic resin or a rosin-modified fuma resin.

As pigments and dyes, general ones are used. If the pigment is black, carbon black (commercially available)
For example, Mitsubishi Kasei # 30, # 40, # 50, MA-1
1. MONARCH 700, 900, R manufactured by Cabot
EGAL 300, 400, 600R, etc.) are preferably used. Further, it is also possible to mix an alkali blue or the like with the carbon black. If it is yellow, benzidine yellow, if it is red, brilliant carmine, fast red, quinacridone red, if it is blue, it is phthalocyanine blue, else phthalocyanine green, oil violet, methyl orange,
Methyl violet and the like are preferably used.

Although the toner particles mainly contain a resin and a colorant, polyethylene glycol, polypropylene glycol and the like may be added for adjusting the softening point.

Further, a charge control agent, wax or the like may be added in the particles or on the surface of the particles for controlling the charge and improving the dispersibility.

The liquid toner of the present invention is dispersed in a petroleum hydrocarbon solvent together with additives such as a resin, a colorant, a charge control agent or a wax by using a ball mill, a vibration mill or an attritor. Can be manufactured. In addition, a resin and a colorant are melt-kneaded in advance using a twin-screw extruder, a kneader, or the like, to produce a colored resin in which the colorant is dispersed in the resin. It can also be produced by dispersing in a hydrocarbon solvent using a ball mill, vibration mill, or attritor.

The average particle size of the toner particles is preferably from 0.2 μm to 5.0 μm, more preferably from 0.5 μm to 2.5 μm. When the average particle size of the toner particles is larger than 5.0 μm, it is difficult to obtain a high-definition image which is a characteristic of the liquid toner.
Toner particles smaller than μm are not preferred because image deterioration such as crushing or flow is likely to occur during transfer from the electrostatic image carrier to the transfer material.

In the above liquid toner, 0.1% by weight or more and 3.0% by weight with respect to the nonvolatile components in the liquid toner.
It preferably contains the following water. More preferably,
It is not less than 0.2% by weight and not more than 2.0% by weight. When the water content is less than 0.1% by weight, the effect of improving the development density is hardly obtained, and the flow of the toner image is liable to occur at the time of transfer to the material to be transferred. When the content of water is more than 3.0% by weight, the developed image is soft, and the flow of the image or the collapse of the image is likely to occur during the transfer to the material to be transferred.

The liquid toner containing a predetermined amount of water is dispersed in a petroleum hydrocarbon solvent together with a resin, a colorant, a charge control agent or an additive such as a wax by adding a predetermined amount of water at the same time. Can be manufactured. At this time, it is preferable that water is previously mixed with the resin. Further, it is more preferable that water is absorbed in the resin by storing the resin in a humidified atmosphere.

In the step of dispersing a pulverized colored resin in which a coloring material is dispersed in a resin in advance in a petroleum hydrocarbon solvent together with an additive such as a charge control agent or a wax, a predetermined amount of water is simultaneously added. It may be manufactured by doing. At this time, it is preferable that water is previously mixed with the colored resin pulverized product. Further, it is more preferable that water is absorbed in the resin by storing the colored resin pulverized product in a humidity control atmosphere.

The reason that the presence of water in the liquid toner improves the development density and also improves the flow and collapse of the image is because part of the water is present on the resin surface,
It is considered to be to improve the charging characteristics of the toner particles. In particular, when the resin is a resin having an acid value of 50 or more and 250 or less, it is presumed that the effect is easily obtained by the interaction of the acidic site in the resin with water.

Next, an image forming apparatus using the liquid toner of the present invention will be described with reference to FIG. 1 taking an electrophotographic printer for color printing as an example.

As shown in FIG. 1, the electrophotographic printer 1 includes a photosensitive unit 10, a developing unit 20, an intermediate transfer unit 30,
The cleaning unit 40 includes a cleaning unit 40, a transfer / fixing unit 50, a cleaning roller 55, a pre-transfer charger 60, and an auxiliary squeezing unit 70. The exposure unit (not shown) emits light for exposure to the photosensitive unit 10.

First, residual charges are removed from the surface of the photosensitive drum 11 cleaned by the cleaning means 40 by the charge removing lamp 12, and the photosensitive drum 11 is uniformly charged by the primary charger 13.

Next, a laser beam is irradiated from the exposure means, and an electrostatic image based on the color-separated print information is sequentially formed on the surface of the photosensitive drum 11. The electrostatic charge image formed by the laser beam irradiation is formed four times in total corresponding to the hues of yellow, magenta, cyan and black.

Next, the developing means 20 disposed on the right side of the photosensitive drum 11 in the figure is moved horizontally to the photosensitive drum 11 side by a driving means (not shown), and the yellow toner image is formed by the first developing unit 21. Second developing unit 22
The magenta toner image is developed in the same manner, and cyan and black toner images are sequentially developed.

In this manner, the toner images developed by the respective developing units are sequentially transferred to the intermediate transfer drum 31, and a full-color toner image in which four color toner images are stacked is formed on the intermediate transfer drum 31. You.

When the transfer of the toner image developed by the fourth developing unit 24 to the intermediate transfer drum 31 is completed, the photosensitive drum 11 and the intermediate transfer drum 31 are separated from each other by a separating and pressing mechanism (not shown). Thereafter, the rotation speed of the intermediate transfer drum 31 decreases. After the rotation speed decreases, the heating rollers 51 and 52 are pressed against the intermediate transfer drum 31 by a pressing mechanism (not shown). As a result, the full-color toner image laminated on the intermediate transfer drum 31 is heated and pressed, and is transferred and fixed on the conveyed recording paper S at a time, thereby completing the process of recording a color image. .

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.

The form of the intermediate transfer member is formed on a separately prepared substrate such as aluminum, iron, or plastic film.
A belt in which at least a conductive layer and a transfer layer are laminated and this sheet is combined may be used, or a drum in which this sheet is wound around a cylindrical rigid body may be used. Also,
A drum in which at least a conductive layer and a transfer layer are directly laminated on a cylindrical rigid body may be used.

[0032]

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

[Method of Measuring Moisture Content] The moisture content was measured using a Karl Fischer moisture meter MKC-2 manufactured by Kyoto Electronics Industry Co., Ltd.
Performed using No. 10.

[Method of Measuring Acid Value] The acid value was measured according to the description in “Painting Handbook”, edited by Shinji Iwai, published by Sangyo Tosho, p. 635, page 635.

[Measurement Method of Softening Point] The softening point was measured according to a ring and ball method. For details of the measurement, see "Synthetic Resin Handbook" (edited by Synthetic Resin Industrial Technology Research Group, 1967, published in Sangyo Tosho), No. 5
The description on page 72 was followed. [Measurement Method of Average Particle Size of Toner Particles] The measurement was performed using a Shimadzu centrifugal sedimentation type particle size distribution analyzer SA-CP3. The liquid toner is diluted with the carrier liquid to match the absorbance range of the instrument. Further, the particle size distribution of this sample was measured from the absorbance change in the acceleration rotation mode at 240 rpm / min, and the average particle size was calculated as the median diameter.

Example 1 Rosin-modified maleic resin "Marquid" No. 32
(Acid value 130, softening point 135 ° C, manufactured by Arakawa Chemical Industries) 1
450 g, yellow pigment 400 g (Fineth Yellow G-20 S12E, manufactured by Toyo Ink Mfg. Co., Ltd.) and 150 g of polyethylene glycol (PEG 6000, manufactured by Sanyo Kasei Co., Ltd.) were twin-screw extruder PCM-30 manufactured by Ikegai Ironworks Co., Ltd.
Then, the kneaded product was pulverized using a sample mill KII-1 manufactured by Fuji Paudal Co., Ltd. to obtain a pulverized colored resin having an average particle size of about 50 μm. The colored resin pulverized product was put in a storage room at room temperature of 20 ± 5 ° C. and humidity of 70 ± 10 RH% and stored for 3 months.

200 g of the colored resin pulverized product and 110 g of an acrylic polymer type charge control agent solution (solid content: 14% by weight, column 24, column 20 of US Pat. No. 3,900,412)
(Prepared by the method described in Example XI described from line 36 to line 36), 15 g of carnauba wax (manufactured by Nikko Products), and 1250 g of "ISOPAR" M (manufactured by Exxon Chemical) as a carrier liquid. Then, a yellow liquid toner was prepared by pulverizing and dispersing for 5 hours with a vibration mill B-3 type manufactured by Chuo Kakoki Co., Ltd. The average particle size of the obtained liquid toner was 0.8 μm. As a result of measuring the water content in the liquid toner by the Karl Fischer method, it was 1.0% by weight with respect to the nonvolatile content. This liquid toner was diluted with Isopar M to a nonvolatile concentration of 2% by weight and used as a developer.

Example 2 A magenta liquid toner was prepared in the same manner as in Example 1 except that Lionol Red 6B FG4213 (manufactured by Toyo Ink Mfg. Co., Ltd.) was used as the magenta pigment instead of the yellow pigment. The particle size of the toner particles in these liquid toners was 0.9 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method.
% By weight.

Example 3 No. 3 was used as a cyan pigment in place of the yellow pigment. 70
A cyan liquid toner was prepared in the same manner as in Example 1, except that 0-10S cyanine blue (manufactured by Toyo Ink Mfg. Co., Ltd.) was used. The particle size of the toner particles in these liquid toners was 0.7 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method.
% By weight.

Example 4 A black liquid toner was prepared in the same manner as in Example 1, except that carbon black Mogal-L (manufactured by Cabot) was used as a black pigment instead of the yellow pigment. The particle size of the toner particles in these liquid toners was 0.9 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method.
% By weight.

As a result of printing using the toners of Examples 1 to 4, the print density was 1.2 or more in all cases. In addition, no thickening of lines and no flow of dots were observed, and a printed matter having good resolving power was obtained.

Comparative Example 1 Rosin-modified maleic resin "Marquid" No. 32
(Acid value 130, softening point 135 ° C, manufactured by Arakawa Chemical Industries) 1
450 g, yellow pigment 400 g (Fineth Yellow G-20 S12E, manufactured by Toyo Ink Mfg. Co., Ltd.) and 150 g of polyethylene glycol (PEG 6000, manufactured by Sanyo Kasei Co., Ltd.) were twin-screw extruder PCM-30 manufactured by Ikegai Ironworks Co., Ltd.
Then, the kneaded product was pulverized using a sample mill KII-1 manufactured by Fuji Paudal Co., Ltd. to obtain a pulverized colored resin having an average particle size of about 50 μm. This colored resin pulverized product was placed in a drying cabinet at room temperature of 20 ± 5 ° C. and a humidity of 10 RH% or less, and stored for 3 months.

200 g of the colored resin pulverized product and 110 g of an acrylic polymer type charge control agent solution (solid content: 14% by weight, column 24, column 20 of US Pat. No. 3,900,412)
(Prepared by the method described in Example XI described from line 36 to line 36), 15 g of carnauba wax (manufactured by Nikko Products), and 1250 g of "ISOPAR" M (manufactured by Exxon Chemical) as a carrier liquid. Then, a liquid toner was prepared by pulverizing and dispersing for 5 hours with a vibration mill B-3 manufactured by Chuo Kakoki Co., Ltd. The average particle size of the obtained liquid toner was 0.8 μm. As a result of measuring the water content in the liquid toner by the Karl Fischer method, it was 0.05% by weight based on the nonvolatile content. This liquid toner was used after being diluted with "Isopar" M to a concentration of 2% by weight of nonvolatile components.

Comparative Example 2 A magenta liquid toner was prepared in the same manner as in Example 1 except that Lionol Red 6B FG4213 (manufactured by Toyo Ink Mfg. Co., Ltd.) was used as the magenta pigment instead of the yellow pigment. The particle size of the toner particles in these liquid toners was 0.9 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method.
It was 5% by weight.

Comparative Example 3 No. 3 was used as a cyan pigment in place of the yellow pigment. 70
A cyan liquid toner was prepared in the same manner as in Example 1, except that 0-10S cyanine blue (manufactured by Toyo Ink Mfg. Co., Ltd.) was used. The particle size of the toner particles in these liquid toners was 0.7 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method.
It was 5% by weight.

Comparative Example 4 A black liquid toner was prepared in the same manner as in Example 1 except that carbon black Mogal-L (manufactured by Cabot) was used as a black pigment instead of the yellow pigment. The particle size of the toner particles in these liquid toners was 0.9 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method.
It was 5% by weight.

As a result of printing using the toners of Comparative Examples 1 to 4, the print density was as low as 1.0 to 1.1 in all cases. In addition, dot flow was observed, and a clear image was not obtained.

Example 5 Rosin-modified maleic resin “Marquid” No. 32
(Acid value 130, softening point 135 ° C, manufactured by Arakawa Chemical Industries) 1
450 g, yellow pigment 400 g (Fineth Yellow G-20 S12E, manufactured by Toyo Ink Mfg. Co., Ltd.) and 150 g of polyethylene glycol (PEG 6000, manufactured by Sanyo Kasei Co., Ltd.) were twin-screw extruder PCM-30 manufactured by Ikegai Ironworks Co., Ltd.
Then, the kneaded product was pulverized using a sample mill KII-1 manufactured by Fuji Paudal Co., Ltd. to obtain a pulverized colored resin having an average particle size of about 50 μm. This colored resin pulverized product was placed in a drying cabinet at room temperature of 20 ± 5 ° C. and a humidity of 10 RH% or less, and stored for 3 months.

After preliminarily mixing 200 g of the colored resin pulverized product and 4 g of water, 110 g of an acrylic polymer type charge control agent solution was obtained.
(Solid content 14% by weight, US Pat. No. 3,900,41
No. 2, column 24, lines 20 to 36, prepared by the method described in Example XI), 15 g of carnauba wax (manufactured by Nikko Products), and "Isopar" M (as a carrier liquid) 1250 g of Exxon Chemical Co., Ltd.) was mixed, and the mixture was pulverized and dispersed in a vibration mill B-3 type manufactured by Chuo Kakoki Co., Ltd. for 5 hours to prepare a liquid toner. The average particle size of the obtained liquid toner was 1.0 μm. As a result of measuring the water content in the liquid toner by the Karl Fischer method, it was 1.7% by weight with respect to the nonvolatile content. This liquid toner was diluted with Isopar M to a nonvolatile concentration of 2% by weight and used as a developer.

Example 6 A magenta liquid toner was prepared in the same manner as in Example 1 except that Lionol Red 6B FG4213 (manufactured by Toyo Ink Mfg. Co., Ltd.) was used instead of the yellow pigment. The particle size of the toner particles in each of these liquid toners was 1.1 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method, and as a result, the non-volatile content was 1.7.
% By weight.

Example 7 Instead of the yellow pigment, No. 1 was used as the cyan pigment. 70
A cyan liquid toner was prepared in the same manner as in Example 1, except that 0-10S cyanine blue (manufactured by Toyo Ink Mfg. Co., Ltd.) was used. The particle size of the toner particles in these liquid toners was 1.0 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method.
% By weight.

Example 8 A black liquid toner was prepared in the same manner as in Example 1 except that carbon black Mogal-L (manufactured by Cabot) was used as a black pigment instead of the yellow pigment. The particle size of the toner particles in these liquid toners was 1.2 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method.
% By weight.

As a result of printing using the toners of Examples 5 to 8, the print density was 1.2 or more in all cases. In addition, no thickening of lines and no flow of dots were observed, and a printed matter having good resolving power was obtained.

Comparative Example 5 Rosin-modified maleic resin "Marquid" No. 32
(Acid value 130, softening point 135 ° C, manufactured by Arakawa Chemical Industries) 1
450 g of yellow pigment 400 g (Fineth Yellow G-20 S12E, manufactured by Toyo Ink Mfg. Co., Ltd.) and 150 g of polyethylene glycol (PEG6000, manufactured by Sanyo Kasei Co., Ltd.) were twin-screw extruder PCM-30 manufactured by Ikegai Iron Works Ltd.
Then, the kneaded product was pulverized using a sample mill KII-1 manufactured by Fuji Paudal Co., Ltd. to obtain a pulverized colored resin having an average particle size of about 50 μm. This colored resin pulverized product was placed in a drying cabinet at room temperature of 20 ± 5 ° C. and a humidity of 10 RH% or less, and stored for 3 months.

After previously mixing 200 g of the colored resin pulverized product and 9 g of water, 110 g of an acrylic polymer type charge control agent solution was mixed.
(Solid content 14% by weight, US Pat. No. 3,900,41
No. 2, column 24, lines 20 to 36, prepared by the method described in Example XI), 15 g of carnauba wax (manufactured by Nikko Products), and "Isopar" M (as a carrier liquid) 1250 g of Exxon Chemical Co., Ltd.) was mixed, and the mixture was pulverized and dispersed in a vibration mill B-3 type manufactured by Chuo Kakoki Co., Ltd. for 5 hours to prepare a liquid toner. The average particle size of the obtained liquid toner was 1.1 μm. As a result of measuring the water content in the liquid toner by the Karl Fischer method, it was 3.9% by weight with respect to the nonvolatile content. This liquid toner was diluted with Isopar M to a nonvolatile concentration of 2% by weight and used as a developer.

Comparative Example 6 A magenta liquid toner was prepared in the same manner as in Example 1, except that Lionol Red 6B FG4213 (manufactured by Toyo Ink Mfg. Co., Ltd.) was used as the magenta pigment instead of the yellow pigment. The particle size of the toner particles in each of these liquid toners was 1.2 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method.
% By weight.

Comparative Example 7 No. 1 was used as a cyan pigment in place of the yellow pigment. 70
A cyan liquid toner was prepared in the same manner as in Example 1, except that 0-10S cyanine blue (manufactured by Toyo Ink Mfg. Co., Ltd.) was used. The particle size of the toner particles in these liquid toners was 1.1 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method.
% By weight.

Comparative Example 8 A black liquid toner was prepared in the same manner as in Example 1 except that carbon black Mogal-L (manufactured by Cabot) was used as a black pigment instead of the yellow pigment. The particle size of the toner particles in these liquid toners was 1.4 μm.

The amount of water in the liquid toner was measured by the Karl Fischer method.
% By weight.

As a result of printing using the toners of Comparative Examples 5 to 8, the print density was as low as 1.0 to 1.1 and the white background was stained as a whole. In addition, fine lines were broken and dots flowed, and the image quality was poor.

[0072]

As described above, the liquid toner of the present invention can improve the developing density and can obtain an image with good resolution without flowing or crushing.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic printer to which an intermediate transfer member of the present invention is applied.

[Explanation of symbols]

1: electrophotographic printer, 10: photosensitive means, 11: photosensitive drum, 12: static elimination lamp, 13: primary charger, 20:
Developing means, 21: first developing unit, 21b: developing roller, 21c: squeeze roller, 22 to 24: second to
Fourth developing unit, 30: intermediate transfer means, 31: intermediate transfer drum, 32: charger, 33: heater, 40: cleaning means, 41: cleaning roller, 42:
Squeeze blade, 50: transfer / fixing means, 51: heating roller, 52: heating roller, 55: cleaning roller, 60: pre-transfer charger, 70: auxiliary squeezing means, 71: auxiliary roller, 72: tray, S: recording paper

Claims (2)

[Claims] 1. A liquid toner for developing an electrostatic image, comprising toner particles containing a resin and a colorant as main components dispersed in a carrier liquid of a petroleum aliphatic hydrocarbon, wherein the liquid toner has a non-volatile content. , 0.1 to 3.0% by weight of water. 2. The liquid toner according to claim 1, wherein the acid value of the resin is 20 or more and 250 or less.