JPH04319961A - Liquid developer for electrophotography - Google Patents

Abstract

PURPOSE:To provide a toner image having a sufficient density and a clear profile by low pressure without toxicity by using a silicone oil as a carrier liquid. CONSTITUTION:A silicone oil is used as a carrier liquid in a developer in which toner, having a main component of a coloring agent and resin, is diffused in a highly insulative low dielectric constant carrier liquid. In this case, developing is conducted with electrified toner selectively adhering to an electrostatic latent image by electrophoresis to form a toner image on a photosensitive body 1. Then the toner image is transferred to an intermediate drum 50 by making an intermediate transfer roller 50 abut on a photosensitive body drum 1 and appliying an electric field. On the other hand, a recording paper 21, as a recording medium, delivered from a paper-feeding device 20 is carried to an abutting position with the intermediate transfer roller 50 to be applied with pressure by a pressing roller 40. Here the toner image on the photosensitive body drum 1 adheres to the recording paper 21 to be transfered.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developer used in wet recording devices such as electrophotographic copying machines and printers.

0002

[Prior Art] As a liquid developer for electrophotography, styrene resin,
There are known toners in which a toner containing a thermoplastic resin such as an acrylic resin, and a coloring agent such as a pigment or dye such as carbon black is dispersed (for example, JP-A-55-35321). A recording method using such a liquid developer involves forming an electrostatic latent image on a photoreceptor, developing it with a liquid developer, transferring it to an intermediate transfer belt, and then transferring this toner image to recording paper. A transfer method (intermediate transfer method) is known (for example, US Pat. No. 4,708,460).

0003

Problems to be Solved by the Invention When using the liquid developer of the prior art described above, problems such as environmental pollution and health safety have come to light because a petroleum-based aliphatic hydrocarbon solvent is used as the carrier liquid. Furthermore, when recording is performed using the above-mentioned intermediate transfer type recording device, there are problems in that the transfer efficiency is poor, and an image with sufficient density and clear outline cannot be obtained on the recording paper. Was. In the intermediate transfer method, the transfer from the intermediate transfer belt to the recording paper is performed by applying pressure between the two. However, it is necessary to increase this pressure in order to provide sufficient adhesion between the toner image and the recording paper. In actual devices, there is a limit to the pressure that can be applied, and sufficient adhesion cannot be obtained, resulting in low transfer efficiency. The purpose of the present invention is to solve these problems, to prevent environmental pollution and to be safe for health, and to provide sufficient information on recording paper with small pressure in an intermediate transfer type recording device. The object of the present invention is to realize a liquid developer for electrophotography that can provide a toner image with high density and clear outline.

0004

[Means for Solving the Problems] The liquid developer for electrophotography of the present invention is a liquid developer for electrophotography which is made by dispersing a toner mainly composed of a colorant and a resin in a highly insulating and low dielectric constant carrier liquid. The liquid developer is characterized in that silicone oil is used as the carrier liquid.

[0005]

[Example] An example of the present invention will be explained. The method for producing the electrophotographic liquid developer of the present invention includes a coloring agent,
Ball mill the resin, and if necessary the usual additives, in the presence of a small amount of silicone oil used as carrier liquid.
The toner may be kneaded and dispersed using an attritor or the like to obtain a concentrated toner, and this may be diluted with an appropriate amount of silicone oil carrier liquid. The appropriate amount of each resin to be used is 1 to 10 parts by weight per 1 part by weight of the colorant. Next, each component will be illustrated. As a coloring agent, carbon black (MA100, #44, #33 manufactured by Mitsubishi Kasei Corporation, Laben 1250, Laben 1020 manufactured by Columbian Carbon, Black Pearl L, Black Pearl 1100 manufactured by Cabot, Printex 55 manufactured by Degussa, Special Black 4, etc.), organic pigments (insoluble azo pigments, soluble azo pigments, phthalocyanine pigments, isoindolinone-based high-grade pigments, quinacridone-based high-grade pigments, perinone/perylene-based high-grade pigments). In addition, oil-based dyes can be used as complementary colors if necessary. Examples of resins include ethyl cellulose, linseed oil-modified alkyd resin, acrylic acid or methacrylic acid ester resin, polystyrene, polystyrene polyolefin copolymer, polyvinyl chloride resin, chlorinated polypropylene,
Examples include polyamide resin, coumaron indene resin, rosin-modified resin, and alkylphenol-modified xylene resin. The silicone oil used as the carrier liquid is preferably one with low viscosity from the viewpoint of physical properties. Specifically, Shin-Etsu Chemical Co., Ltd. KF96L (1.0cs, 1.5cs, 2.0c
s) TSF404, TSF405 manufactured by Toshiba Silicone Co., Ltd.
There are TSF406, TSF451-5A, and TSF400. In addition, additives such as charge control agents can also be used as necessary. Next, specific examples of electrophotographic liquid developers made from the above components will be shown.

Example 1 Polystyrene (QP3-301 manufactured by Denki Kagaku Kogyo Co., Ltd.)
30g carbon black (MA100 manufactured by Mitsubishi Chemical Industries, Ltd.)
12g calcium naphthenate (charge control agent)
0.
2g silicone oil KF96L1.0cs (manufactured by Shin-Etsu Chemical Co., Ltd.) 157.8g The above mixture was dispersed in an attritor for 8 hours, and then silicone oil KF96L1.0cs was dispersed in an attritor for 8 hours.
Add 300g of 0cs and disperse for 1 hour to make a concentrated liquid, then add 200g of it to silicone oil KF96L1.0c.
A liquid developer for electrophotography was obtained by diluting the solution to 1000 g.

Comparative Example 1 A liquid developer for electrophotography was obtained in the same manner as in Example 1 except that Isopar G (an aliphatic hydrocarbon solvent manufactured by Exxon Chemical Co., Ltd.) was used instead of the silicone oil. Example 2 Rosin-modified pentaerythritol maleate ester (
Pentaline G manufactured by Rika Hercules)

60g carbon black (Laben 12 manufactured by Columbian Carbon Co., Ltd.
50) 12g Cobalt naphthenate (charge control agent)
0.2g silicone oil T
SF404 (manufactured by Toshiba Silicone Corporation) 127
．． A liquid developer for electrophotography was obtained from 8 g of the above mixture in the same manner as in Example 1.

Comparative Example 2 A liquid developer for electrophotography was obtained in the same manner as in Example 2, except that Isopar H (an aliphatic hydrocarbon solvent manufactured by Exxon Chemical Co., Ltd.) was used instead of the silicone oil. Example 3 Coumaron-indene resin (S-Clone G manufactured by Nippon Steel Chemical Co., Ltd.)
90) 100g organic pigment (phthalocyanine blue)
12g Calcium naphthenate (charge control agent)
0.2g silicone oil KF
96L1.5cs (manufactured by Shin-Etsu Chemical Co., Ltd.) 87.8g
A liquid developer for electrophotography was obtained from the mixture in the same manner as in Example 1.

Comparative Example 3 A liquid developer for electrophotography was obtained in the same manner as in Example 3, except that Isopar H (an aliphatic hydrocarbon solvent manufactured by Exxon Chemical Co., Ltd.) was used instead of the silicone oil. The electrophotographic liquid developers of Examples 1 to 3 and Comparative Examples 1 to 3 were recorded on various recording papers in the following manner.

FIG. 1 is a sectional view of an intermediate transfer type recording apparatus using the electrophotographic liquid developer of the present invention. Around the photoreceptor drum 1, a charging device 2, an exposure device 3, a developing device 4, an intermediate transfer drum 50, a pressure roller 40, a peeling claw 6,
A cleaning device 7 and a static eliminator 8 are arranged in this order. The pressure roller 50 is composed of a metal hollow drum 51 and an elastic layer 52 covering the drum. The elastic layer 52 is preferably capable of absorbing the carrier liquid, and such an elastic layer can be obtained by using silicone rubber. The transfer roller 50 is provided with a cleaning device 57 that removes toner remaining after transfer.

The recording operation is performed as follows. An electrostatic latent image is formed on the photoreceptor drum 1 through a charging process and an exposure process. The electrostatic latent image is developed by a developing device 4 using a liquid developer. Development is performed by selectively attaching charged toner to the electrostatic latent image by electrophoresis, and the photoreceptor 1
A toner image is formed thereon. Next, the intermediate transfer roller 50 and the photosensitive drum 1 are brought into contact with each other and an electric field is applied to transfer the toner image onto the intermediate transfer drum 50. On the other hand, the paper feeding device 20
The recording paper 21, which is a recording medium, is conveyed to a position where it contacts the intermediate transfer roller 50. Pressure is applied by a pressure roller 40. Here, the toner image on the photosensitive drum 1 adheres to the recording paper 21 and is transferred. The recording paper 21 on which the toner image has been transferred is further conveyed to the transfer device 10, fixed by heat and pressure, and stored in the paper discharge tray 21-1.

[0012] When bit image recording and character recording were performed on general high-quality paper, bond paper, and PPC paper using the above recording method, it was found that even better recording was possible than in the comparative example regardless of the type of recording paper. confirmed.

[0013]

Effects of the Invention As mentioned above, the liquid developer for electrophotography of the present invention has almost no toxicity because it uses silicone oil. Another advantage is that a toner image with sufficient density and clear outline can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a recording apparatus used for recording with the electrophotographic liquid developer of the present invention.

[Explanation of symbols]

1 Photoreceptor drum 10 Heat fixing device 21 Recording paper 50 Intermediate transfer drum

Claims (1)

[Claims] 1. A liquid developer for electrophotography comprising a toner mainly composed of a colorant and a resin dispersed in a highly insulating and low dielectric constant carrier liquid, in which silicone oil is used as the carrier liquid. Characteristic liquid developer for electrophotography.