JP2002351155A - Electrostatic liquid developer and image forming method using the same - Google Patents

Abstract

(57) [Summary] An electrophotographic liquid developer that has improved fixability immediately after copying, has a high image density, and can provide a high-resolution image,
And an image forming method using the same. SOLUTION: This is a liquid developer for electrophotography in which a toner comprising a resin containing a colorant and an ethylene copolymer is dispersed in silicone oil, and has a solid content of 10 to 50% by weight.
0.3 g of a silicone oil dispersion containing the toner of No. 2. A liquid developer for electrophotography, wherein the speed of diffusion of silicone oil around a formed toner layer having a diameter of 5 mm is 1 to 50 mm / min. .

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid developer used for electrophotography, electrostatic recording, electrostatic printing, and the like, and an image forming method using the same.

[0002]

2. Description of the Related Art High-boiling aliphatic hydrocarbons and silicone oils are used as dispersants in electrophotographic wet developers, whereas conventional electrophotographic liquid developers are applied to wet developing copiers. After the copying, the silicone oil in the image area is easily diffused into the transfer paper over time, but the fixability of the copy image is good.However, the dispersant on the toner layer or paper reduces the fixability immediately after copying. There was a drawback that the image area disappeared when the finger was rubbed badly.

[0003]

An object of the present invention is to provide a liquid developer for electrophotography in which the fixability immediately after copying is improved, a high image density and a high-resolution image can be obtained, and an image forming method using the same. The purpose is to provide.

[0004]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that a liquid developer for electrophotography using silicone oil as a dispersion medium has a diffusion rate of silicone oil in a toner dispersion liquid of It has been found that the object can be achieved by using a material having a speed of 1 to 50 mm / min. That is, the above problems are solved by the following inventions 1) to 6). 1) A liquid developer for electrophotography in which a toner comprising a resin containing a colorant and an ethylene copolymer is dispersed in silicone oil, and a silicone oil dispersion containing a toner having a solid content of 10 to 50% by weight. 0.3 g of Toyo Roshi Kaisha No. 2 from the height of 10 mm on the filter paper,
A liquid developer for electrostatography, wherein the speed of diffusion of silicone oil around a formed toner layer having a diameter of 5 mm is 1 to 50 mm / min. 2) The liquid developer for electrophotography according to 1), wherein the resin contains an ethylene / vinyl acetate copolymer, an ethylene / acrylic acid copolymer, or an ethylene / acrylate copolymer. 3) The liquid developer for electrophotography according to 1) or 2), wherein the colorant is a pigment coated with a resin. 4) The liquid developer for electrostatography according to 3), wherein the colorant is coated by a flushing method in the presence of humic acid, a humic acid salt, or a humic acid derivative. 5) The liquid developer according to any one of 1) to 4),
An image forming method, comprising: performing corona discharge on a liquid toner layer for an electrostatic image formed on a roller or a belt, and then developing an electrostatic latent image. (6) The image forming method according to (5), wherein the pre-wet liquid is applied to the electrostatic latent image portion and then developed. 7) The image formation according to 5) or 6), wherein after the electrostatic latent image is developed to form a toner image, the toner image is transferred to an intermediate transfer member, and then an image is formed on a transfer member. Method. 8) The image forming method according to any one of 5) to 7), wherein the surface of the photoconductor forming the electrostatic latent image has water repellency and oil repellency (contact angle θ = 30 ° or more). .

Hereinafter, the present invention will be described in detail. The liquid developer for electrostatography of the present invention is a colorant, a resin,
And a silicone oil as a dispersion medium. The colorant and the resin are used in a weight ratio of the colorant: the resin = 1: 0.3 to 10, and an appropriate amount of the silicone oil is appropriately used. As the resin, those that can be dispersed in silicone oil are used.As the coloring agent, ethylene / vinyl acetate copolymer, ethylene / acrylic acid or ethylene / acrylic acid ester copolymer or other ethylene copolymer, A substance containing at least humic acid, a humic acid salt, or a humic acid derivative and subjected to a flushing process is preferably used. Silicone oil is KF96 1-1000
0cst (Shin-Etsu Silicon Co., Ltd.), SH200, SH34
4 (manufactured by Toray Silicon Co., Ltd.) and TSF451 (manufactured by Toshiba Silicon Co., Ltd.), and decamethyltetrasiloxane, octamethyltrisiloxane, and the like may be used.

The toner used in the present invention is such that when an image is formed by an electrostatic copying machine, when a toner layer on a photoreceptor is transferred onto transfer paper, silicone oil as a dispersion medium is dispersed from the toner layer on the transfer paper. It has the property of rapidly diffusing into paper and improving the primary fixing property. The means for measuring the diffusion speed of the silicone oil, which is the dispersion medium of the toner, will be described with reference to FIGS. For example, using a measuring device as shown in FIG. 5, 0.3 g of a dispersion containing toner having a solid content of 10 to 50% by weight was taken with a measuring cylinder, and from a height of 10 mm, No. 2 When the toner is dropped on the filter paper using a toner dropping buret, a toner layer having a diameter of about 5 mm is formed as shown in FIG. 6, and the silicone oil as a dispersion medium is diffused around the toner layer. Here, while measuring the diameter of the silicone oil layer with a caliper, the diameter is 1 mm.
The time until it becomes is measured with a stopwatch. In the present invention, one having a diffusion speed of 1 to 50 mm / min is used. If it is less than 1 mm / min, it is not preferable because sufficient primary fixing property cannot be obtained, and if it is more than 50 mm / min, the separation from the silicone oil is too fast and the temporal stability is unfavorably reduced. It has also been found that the higher the diffusion speed, the better the primary fixing property. In addition, the amount of solid content is 10 to 50.
The reason for the percentage by weight is that if the amount is too small, the function as a toner cannot be achieved, and if the amount is too large, the viscosity is too high and the developability deteriorates.

The constitution and production method of the coloring agent used in the present invention are disclosed in detail in JP-A-59-102253. In the present invention, ethylene-vinyl acetate copolymer, ethylene copolymer such as ethylene-acrylic acid copolymer or ethylene-acrylic acid ester copolymer, and humic acid, humic acid salt or humic acid derivative at least Use the contained coloring agent. The weight ratio of the pigment, humic acid and resin in the colorant particles is preferably pigment: humic acid: resin = 1: 0.001-1: 0.5-9.

Examples of inorganic pigments used in the colorant include furnace black, acetylene black, and channel black as carbon black, and PRINTEX G, PRINTEX V, special black 15, special black 4, and special black 4 as commercial products.
-B (made by Degussa), Mitsubishi # 44, # 30, MA-1
1, MA-100 (Mitsubishi Carbon), Raven 3
0, Raven 40, Conductex SC (manufactured by Columbia Carbon), Regal 400, 660, 800, Black Pearl L (manufactured by Cabot) and the like.
Further, inorganic white pigments such as zinc oxide, titanium oxide and silicon oxide may be used.

Examples of the organic pigment include phthalocyanine blue, phthalocyanine green, rhodamine lake, malachite green lake, methyl violet lake, peacock blue lake, naphthol green B, permanent red 4R, Hanza yellow, benzidine yellow, and thioindigo red. . The organic pigment and the inorganic pigment may be used alone or as a mixture. The pigment used is preferably coated with a resin. The resin for coating the pigment preferably contains at least an ethylene / vinyl acetate copolymer, and is used by mixing a polyolefin, an acrylic resin, a rosin-modified resin, a styrene / butadiene resin, a natural resin, and other resins. You can do it. As ethylene-vinyl acetate copolymer,
Brands commercially available from Mitsui-Dupont Polychemical Co., Ltd. can be mentioned.

Next, a production example of a coloring agent will be described. The colorant obtained by coating the pigment with a resin can be obtained by a flushing method, but of course, another method may be used. Preferably, humic acid, a humic acid salt or a derivative of humic acid is used during the pigment dispersion step. <Coloring agent production example-1> 20 g of ammonium humate was dissolved well in 200 g of water, and carbon (Mitsubishi # 44) 25
0 g was added and mixed and dispersed well in a gallon kneader. Next, 750 g of Evaflex 45X (manufactured by DuPont-Mitsui Polychemicals) was added, heated to 100 ° C. and mixed, and then water was separated. After further kneading at 120 ° C. for 4 hours, the mixture was vacuum dried, cooled and pulverized to obtain a colorant.

<Production Example 2 of Colorant> 10 g of sodium humate was dissolved in 200 g of water, and 250 g of carbon (Mogal A) (manufactured by Columbia Carbon Co., Ltd.) was added and mixed and dispersed well in a gallon kneader. Next, 300 g of Sunwax 151P and 300 g of Evaflex 210
The mixture was heated to 150 ° C. and kneaded. The mixture was further kneaded at 120 ° C. for 2 hours, dried in vacuum, cooled and pulverized to obtain a colorant. Following Examples 3 to 1 in accordance with the procedure of Colorant Production Example-1
A colorant of 0 was prepared as follows.

[0012]

[Table 1]

Next, the constitution and production method of the resin used in the present invention will be described. Examples of the resin used in the present invention include a vinyl monomer represented by the following general formulas (1) and (2), a vinyl monomer represented by the following general formula (3), vinyl pyridine, vinyl pyrrolidone, ethylene glycol dimethacrylate, Styrene, divinylbenzene, copolymer consisting of each one of the monomers selected from vinyl toluene,
Alternatively, a copolymer or a graft copolymer composed of several types thereof may be used.

Embedded image CH ₂ ＣＲCR ¹ —COOC _n H _{2n + 1} (1) (wherein, R ¹ represents H or CH ₃ , and n represents an integer of 6 to 20)

Embedded image CH ₂ ＣＲCR ¹ —OCOC _n H _{2n + 1} (2) (wherein, R ¹ represents H or CH ₃ , and n represents an integer of 6 to 20)

Embedded image CH₂= CR¹-COOR² (3) ｛where R¹Is H or CH₃And R²Is H, C_nH
_{2n + 1} [N = 1-5], CH₂CH = CH₂, C₂H
₄OH or C₂H₄N (C_mH_{2m + 1})₂[M = 1
To 4]. ｝

Specific examples of the monomers represented by the general formulas (1) and (2) include lauryl methacrylate, lauryl acrylate, stearyl methacrylate, stearyl acrylate, 2-ethylhexyl methacrylate, 2-ethylhexyl acrylate, dodecyl methacrylate, dodecyl acrylate, and hexyl methacrylate. , Hexyl acrylate, octyl methacrylate, octyl acrylate, cetyl methacrylate, cetyl acrylate, vinyl laurate, vinyl stearate and the like. Specific examples of the monomer having an allyl group of the general formula (3) include allyl methacrylate, allyl acrylate, allyl propyl methacrylate, allyl propyl acrylate, allyl butyl methacrylate, allyl butyl acrylate, allyl pentyl methacrylate,
Allyl pentyl acrylate, allyl hexyl methacrylate, allyl hexyl acrylate and the like can be mentioned.

Next, a production example of the resin will be described. <Resin Production Example-1> 1000 g of isododecane was placed in a 2-liter four-necked flask and heated to 90 ° C. next,
After 300 g of stearyl methacrylate, 20 g of allyl methacrylate and 3 g of benzoyl peroxide were added dropwise over 1 hour, polymerization was carried out at 90 ° C. for 6 hours. Further, 100 g of a vinyl acetate monomer and 4 g of azobisisobutyronitrile were added dropwise over 1 hour, followed by polymerization at 90 ° C. for 6 hours to obtain a resin having a polymerization rate of 93.8% and a viscosity of 380 cps.

<Resin Production Example-2> KF-96 10cst (manufactured by Shin-Etsu Silicon Co., Ltd.) in a 2 liter four-necked flask
1000 g was taken and heated to 85 ° C. Next, 300 g of lauryl methacrylate, glycidyl methacrylate 2
0 g, methacrylic acid 3 g, allyl methacrylate 10
g and 2 g of benzoyl peroxide were added dropwise over 1.5 hours, and then polymerized at 90 ° C. for 5 hours. Then pyridine 0.
After adding 2 g and stirring at 90 ° C. for 2 hours, 80 g of methyl methacrylate and 4 g of azobisisobutyronitrile were added.
It was dropped over time. Subsequently, the mixture was polymerized at 90 ° C. for 3 hours to obtain a resin having a polymerization rate of 95.0% and a viscosity of 530 cps.

<Resin Production Example-3> KF-96 10cst (manufactured by Shin-Etsu Silicon Co., Ltd.) in a 2 liter four-necked flask
1000 g were taken and heated to 90 ° C. Next, 300 g of lauryl methacrylate, 20 g of allyl propyl methacrylate, 2 g of itaconic acid and 3 g of benzoyl peroxide
After dropwise addition over time, polymerization was carried out at 90 ° C. for 6 hours. Next, 100 g of a vinyl acetate monomer and 4 g of azobisisobutyronitrile were added dropwise over 1 hour.
Polymerization was carried out for a time to obtain a resin having a polymerization rate of 93.0% and a viscosity of 130 cps.

<Resin Production Example-4> KF-96 10cst (manufactured by Shin-Etsu Silicon Co., Ltd.) in a 2 liter four-necked flask
1000 g were taken and heated to 90 ° C. Next, 300 g of stearyl acrylate and allyl butyl acrylate 1
After 0 g, 4 g of fumaric acid and 3 g of benzoyl peroxide were added dropwise over 1 hour, polymerization was carried out at 90 ° C. for 6 hours. Next, 100 g of n-butyl methacrylate monomer and 4 g of azobisisobutyronitrile were added dropwise over 1 hour, and polymerized at 85 ° C. for 6 hours to obtain a resin having a polymerization rate of 96.4% and a viscosity of 890 cps.

<Resin Production Example-5> KF-96 10cst (manufactured by Shin-Etsu Silicon Co., Ltd.) in a 2 liter four-necked flask
1000 g were taken and heated to 90 ° C. Next, 300 g of 2-ethylhexyl acrylate, 30 g of allylhexyl methacrylate, 2 g of diethylaminoethyl methacrylate, and 3 g of benzoyl peroxide were added dropwise over 1 hour, followed by polymerization at 90 ° C. for 6 hours. Next, 100 g of methyl methacrylate monomer and 4 g of azobisisobutyronitrile were added dropwise over 1 hour, and polymerized at 85 ° C. for 6 hours to obtain a resin having a polymerization rate of 92.8% and a viscosity of 260 cps.

<Resin Production Example-6> KF-96 10cst (manufactured by Shin-Etsu Silicon Co., Ltd.) in a 2 liter four-necked flask
1000 g were taken and heated to 90 ° C. Next, 300 g of decyl acrylate, allyl heptyl methacrylate 1
0 g, 3 g of glycidyl methacrylate and 3 g of benzoyl peroxide were added dropwise over 1 hour, followed by polymerization at 90 ° C. for 6 hours. Next, 200 g of vinyl toluene monomer and 4 g of azobisisobutyronitrile were added dropwise over 1 hour, and polymerized at 85 ° C. for 6 hours to obtain a resin having a polymerization rate of 97.7% and a viscosity of 480 cps.

Next, a method for producing the toner will be described. The dispersion is performed by a ball mill, an attritor, a vibration mill method, or the like.
The mixing ratio between the colorant and the resin is as follows: colorant: resin = 1: 0.3
The solid content ratio is adjusted with an appropriate amount of silicone oil. The dispersion time is suitably from 10 to 20 hours, and a concentrated toner can be obtained. If the softening point of the colorant is low, the toner layer on the photoreceptor becomes soft, which may cause image collapse at the time of transfer, resulting in deterioration of sharpness and resolution. The improvement can be achieved by dispersing large particles having a diameter of about 1 to 20 μm in the toner in a small amount. Preferred polymer materials used for such purposes include vinyl chloride resin, styrene resin, acrylic resin, phenolic resin, rosin-modified resin, petroleum resin, butadiene resin, fine powder of polyolefin and the like, fine particle resin by suspension polymerization and the like. Is mentioned.

Further, a high-density and high-resolution image can be obtained by applying the liquid developer in a thin layer on a roller or a belt and developing it. The layer thickness is preferably about 1 to 15 μm, more preferably 3 to 10 μm. If the layer thickness is less than 1 μm, the density is not sufficient, and if it exceeds 15 μm, the resolution is reduced. After performing corona discharge on the liquid toner layer for electrostatic image formed on the roller or the belt, the electrostatic latent image is developed, whereby the cofusion of the toner can be increased, and the resolution can be further improved. Corona discharge is highly effective when it has the same polarity as the toner, and the voltage is preferably about 500 to 8000 V.

After the prewetting liquid is applied to the electrostatic latent image portion, development is performed to improve transfer efficiency and obtain high image quality. The thickness of the pre-wet liquid film is 0.1 to 5
μm, preferably about 0.3 to 1 μm. 0.1
If it is less than μm, the effect is small, and if it exceeds 5 μm, the resolution is reduced. After the electrostatic latent image is developed, the toner image is transferred to the intermediate transfer body, and then the image is formed on the transfer member. Can be obtained. The material of the intermediate transfer member is preferably a solvent-resistant or elastic material such as urethane rubber, nitrile rubber, and hydrin rubber,
It is more preferable that the coating is performed with a fluorine resin or the like. By making the surface of the photoconductor forming the electrostatic latent image water-repellent and oil-repellent (contact angle θ = 30 ° or more), the transfer rate and the cleaning property can be improved, and the image quality can be improved. In order to enhance the water repellency and oil repellency, for example, a fluoropolymer-containing block polymer such as MODIPER F200 or 210 manufactured by NOF Corporation may be coated. However, the contact angle is 1
If the angle is more than 20 °, the toner is disturbed, which is not preferable.

Hereinafter, an image forming process of the image forming method of the present invention will be described with reference to FIGS. In FIG. 1, L is a photoconductor (for example, organic optical semiconductor, selenium, amorphous silicone) rotating in the direction of the arrow,
This is charged by the corona charging unit E while rotating. F is a roller for prewetting the carrier liquid, and G is a writing exposure unit. K is a developing roller, and the toner supplied from the toner container I is uniformly applied by the toner roller J. A voltage is applied to the toner layer on the developing roller K by a corona discharge unit H as needed, and the latent image on the photoconductor L is developed by the developing roller K and visualized. Each roller is made of metal, rubber,
Those made of plastic, sponge and the like, and those having grooves such as wire bars and gravure rollers can also be used. The toner image on the photoconductor L is transferred onto the transfer member B by the transfer roller A. An image is formed on the transfer member B by using pressure, corona discharge, heating, heating and pressure, corona discharge and pressure, a combination of corona discharge and heating, and the like as transfer means. The remaining toner is removed by a cleaning roller C and a cleaning blade D for cleaning the surface of the photoconductor L to prepare for the next image formation.

FIG. 2 differs from FIG. 1 in that it includes a step of coating the pre-wet liquid with a felt F 'instead of a roller. The prewetting liquid is applied as needed. The toner is applied from the toner container I to the developing roller K via the toner rollers J1 and J2, and a DC voltage is applied to the applied toner layer from the corona discharge unit H. The developing roller K in FIG. 2 has a longer contact width with the photoconductor L than in FIG. 1, and is designed to sufficiently develop a latent image.
The toner image developed on photoconductor L is transferred to transfer roller A
Is transferred to the transfer member B to form an image. FIG.
Shows an example of a developing process when a color copy is output. A toner container I for yellow, magenta, cyan, and black and a toner roller J are provided on the photoconductor L. The latent image of the photoconductor L is developed for each color, and is transferred to the intermediate transfer member M. Thus, the image is transferred to the transfer member B by pressure, corona, heat or the like. FIG. 4 is a diagram showing an image forming process for color copying. As in FIG. 3, there are a toner container I containing yellow, magenta, cyan, and black toners, a toner roller J, and a developing roller K.
The latent image on the photoconductor L is developed by the belt N for applying a toner layer to the toner image, and the toner image is transferred to the transfer member B. The belt N for applying the toner layer is cleaned by a cleaning roller O and a cleaning blade P.

Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1 A toner material having the following formulation was charged into an attritor,
For 10 hours to prepare a concentrated toner. -Coloring agent 200 g of coloring agent production example-1-Resin 500 g of resin production example-2 Next, silicone oil KF-96 1 was used as a dispersion medium.
00cst (Shin-Etsu Silicon Co., Ltd.) to add 10% solids
And The diffusion rate of the silicone oil was 2.0 mm / min.

Example 2 A toner material having the following formulation was charged into a ball mill and dispersed at 30 ° C. for 20 hours to prepare a concentrated toner. -Colorant: 400 g of Colorant Production Example-1-Resin: 600 g of Resin Production Example-3 Next, silicone oil KF-96 1 was used as a dispersion medium.
00cst (Shin-Etsu Silicon Co., Ltd.) to add 18% solids
And The diffusion rate of the silicone oil was 2.5 mm / min.

Example 3 A toner material having the following formulation was charged into a ball mill and dispersed at 40 ° C. for 15 hours to prepare a concentrated toner. Colorant Colorant Production Example-3 400 g Resin Resin Production Example-4 600 g Resin powder BR-102 (Mitsubishi Rayon Co., Ltd. acrylic resin) was pulverized to obtain resin particles 10 g having an average particle size of 10 μm.
Is dispersed, and silicone oil KF-96 is used as a dispersion medium.
100 cst (Shin-Etsu Silicon Co., Ltd.) was added and the solid content was 20
%. The diffusion speed of the silicone oil is 3.8 mm /
Minutes.

Example 4 A toner material having the following formulation was charged into an attritor,
For 10 hours to prepare a concentrated toner. -Colorant 500g of Colorant Production Example-4 500g-Resin Resin Production Example-5 500g Next, silicone oil KF-965 as a dispersion medium
0 cst (Shin-Etsu Silicon Co., Ltd.) was added to adjust the solid content to 50%. The diffusion rate of the silicone oil was 2.5 mm / min.

Example 5 A toner material having the following composition was kneaded using a three-roll mill, and after 4 hours, silicone oil KF-9 was used as a dispersion medium.
1500 g of 650 cst (manufactured by Shin-Etsu Silicon) was added and diluted. The diffusion rate of silicone oil is 1.2mm /
Minutes.・ Coloring agent Coloring agent production example-7 500g ・ Resin Resin production example-6 thing 1000g

Example 6 A toner material having the following formulation was charged into a ball mill and dispersed at 25 ° C. for 30 hours to prepare a concentrated toner. The diffusion rate of the silicone oil was 1.6 mm / min.・ Coloring agent Production Example-8 500g ・ Resin Production Example-5 1000g ・ BR-89 (acrylic resin, manufactured by Mitsubishi Rayon) 50g ・ Silicone oil KF-96 50cst 1500g

Comparative Example 1 A developer was prepared in the same manner as in Example 1 except that picotex (petroleum resin) was used instead of Evaflex 45X of Colorant Production Example 1 and the resin of Resin Production Example 2 was not used. It was prepared and the diffusion rate of silicone oil was examined.
mm / min.

Using the liquid developers of Examples 1 to 6 and Comparative Example 1, an image was formed using the apparatus shown in FIG. 1 and the fixability was evaluated. The results shown in Table 1 below were obtained.

[Table 2]

Example 7 Using the developer of Example 1 and applying a 5000 V corona discharge to the toner layer using the apparatus of FIG. 2, development was performed. As a result, the resolution was improved as shown in Table 2 below. did.

[Table 3]

Example 8 Using the developer of Example 2, the latent image on the photoconductor was pre-wet with a pre-wet roller F using the apparatus shown in FIG. 2 with silicone oil KF-96 300 cst (Shin-Etsu Silicon Co., Ltd.).
When pre-wetting (layer thickness: 0.5 μm) was performed to produce an image, the image density, resolution, and transfer rate were improved as shown in Table 3 below.

[Table 4]

Example 9 Using the developer of Example 3, an image was formed using an apparatus equipped with an intermediate transfer drum M (urethane rubber, surface fluorine treatment) shown in FIG. As shown, the image density, resolution, and transfer rate were improved.

[Table 5]

Example 10 Using the developer of Example 4, the photoconductor of the apparatus shown in FIG. 4 was subjected to an oil-repellent treatment (film thickness 2 μm) with a fluorine-acryl block copolymer resin (MODIPA F210 manufactured by NOF Corporation). When an image was taken out, the image density, resolution, and transfer rate were improved as shown in Table 5 below. The contact angle of KF-96 100 cst (manufactured by Shin-Etsu Silicon Co., Ltd.) was 45 °.

[Table 6]

[0039]

According to the present invention 1, a liquid developer for electrostatography having excellent fixability can be provided. According to the present inventions 2 to 4, it is possible to provide a liquid developer for electrostatography which is more excellent in fixing property than the present invention 1. According to the fifth aspect, it is possible to provide an image forming method with improved resolution and sharpness. According to the sixth to eighth aspects of the present invention, it is possible to provide an image forming method in which transferability is improved and image density and resolution are improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an image forming process of an image forming method according to the present invention.

FIG. 2 is a view showing another image forming process of the image forming method of the present invention.

FIG. 3 is a diagram illustrating an example of a development process when a color copy is output.

FIG. 4 is a diagram showing an image forming process for color copying.

FIG. 5 is a diagram showing an example of a diffusion velocity measuring device.

FIG. 6 is a diagram showing a state where a dispersion liquid is dropped on filter paper.

[Explanation of symbols]

 Reference Signs List A transfer roller B transfer member C cleaning roller D cleaning blade E corona charging section F roller F 'felt G writing exposure section H corona discharge section I toner container J toner roller J1 toner roller J2 toner roller K developing roller L photoconductor M intermediate Transfer drum N Belt for applying toner layer O Cleaning roller P Cleaning blade

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Aiko Ishikawa 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (Reference) 2H068 AA04 AA08 2H069 BA00 CA02 CA04 CA28 DA00 2H074 AA03 AA04

Claims (8)

[Claims] 1. A liquid developer for electrophotography, wherein a toner comprising a resin containing a colorant and an ethylene copolymer is dispersed in silicone oil, wherein the solid content is 10 to 50% by weight.
0.3 g of a silicone oil dispersion containing the toner of No. 2. A liquid developer for electrophotography, wherein the speed of diffusion of silicone oil around a formed toner layer having a diameter of 5 mm is 1 to 50 mm / min. . 2. The electrophotographic apparatus according to claim 1, wherein the resin contains an ethylene / vinyl acetate copolymer, an ethylene / acrylic acid copolymer, or an ethylene / acrylate ester copolymer. Liquid developer. 3. The liquid developer for electrostatography according to claim 1, wherein the colorant is obtained by coating a pigment with a resin. 4. The colorant is humic acid, humic acid salt,
4. The liquid developer for electrostatography according to claim 3, wherein the liquid developer is coated by a flushing method in the presence of a humic acid derivative. 5. An electrostatic latent image is developed after performing corona discharge on a liquid toner layer for an electrostatic image formed on a roller or a belt using the liquid developer according to claim 1. An image forming method. 6. The image forming method according to claim 5, wherein the pre-wetting liquid is applied to the electrostatic latent image portion and then developed. 7. The image forming apparatus according to claim 5, wherein after forming the toner image by developing the electrostatic latent image, the toner image is transferred to an intermediate transfer member, and then an image is formed on a transfer member. Image forming method. 8. The photoconductor according to claim 5, wherein the surface of the photoconductor forming the electrostatic latent image has water and oil repellency (contact angle θ = 30 ° to 120 °). The image forming method as described in the above.