JPH04307564A - Liquid developer for electrophotography - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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, the transfer efficiency is poor, especially when recording is performed with the above-mentioned intermediate transfer type recording device, and it is difficult to obtain a sufficient density on the recording paper. There were problems in that an image could not be obtained and an image with a clear outline could not be obtained. In the intermediate transfer method, the transfer from the intermediate transfer belt to the recording paper is performed by applying pressure between the two. This pressure needs to be increased in order to provide sufficient adhesion between the toner image and the recording paper. However, in actual equipment,
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 and to provide an electronic system that can obtain toner images of sufficient density and clear contours on recording paper with a small pressure, mainly in intermediate transfer type recording apparatuses. The objective is to realize a photographic liquid developer.

[0005]

[Function]Although it is known that the aluminum oxide acylate used in the present invention is effective in preventing the settling of pigments in paint, adding lubricating oil, etc. The present invention was completed by discovering that liquid developers are also effective in improving image quality.

[0006]

[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 the carrier liquid contains soluble aluminum oxide acylate.

[0007]

[Example] An example of the present invention will be explained.

[0008] The method for producing the electrophotographic liquid developer of the present invention involves adding a colorant, resin, aluminum oxide acylate and, if necessary, conventional additives in a ball mill in the presence of a small amount of a highly insulating and low dielectric carrier liquid. The toner may be kneaded and dispersed using a means such as an attritor or the like to form a concentrated toner, and this may be diluted with an appropriate amount of carrier liquid. The appropriate amounts of the resin and aluminum oxide acylate to be used are 1 to 10 parts by weight and 0.01 to 1 part by weight, respectively, per 1 part by weight of the colorant.

Next, each component will be illustrated.

As a coloring agent, carbon black (Mitsubishi Chemical Corporation MA100, #44, #33, Columbian Carbon Co., Ltd. Laben 1250, Laben 1020, Cabot Corporation Black Pearl L, Black Pearl 1100) is used.
, Degussa Printex 55, 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 the resin include ethyl cellulose, linseed oil modified alkyd resin, acrylic acid or methacrylic acid ester resin, polystyrene, polystyrene polyolefin copolymer, polyvinyl chloride resin, chlorinated polypropylene, polyamide resin, coumaron indene resin, Examples include rosin-modified resin and alkylphenol-modified xylene resin.

[0012] The carrier liquid has high insulating properties (resistance value 1010
Ωcm or more), low dielectric constant (relative permittivity 3 or less) solvent, n
Aliphatic hydrocarbons such as -hexane, n-heptane, n-nonane, n-octane, iso-octane, iso-dodecane, and mixtures thereof (Isopar from Exxon Chemical Co., IP Solvent from Idemitsu Petrochemical Co., etc.) are used.

[0013] The aluminum oxide acylate may be used as long as it is soluble in the carrier liquid, such as OLYP AO.
There are O, OLYP AOS, etc. 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 (manufactured by Denki Kagaku Kogyo Co., Ltd. QP3-301) 30
g Carbon black (Mitsubishi Chemical Industries, Ltd. MA100) 12
g Aluminum oxide octlate (OLIP AOO manufactured by Hope Pharmaceuticals) 0.6 g Carrier liquid (Isopar G manufactured by Exxon Chemical Co., Ltd.) 157.4 g
These mixtures were dispersed in an attritor for 8 hours, and then 300 g of Isopar G was added and dispersed for 1 hour to obtain a concentrated solution, and 200 g of the mixture was diluted to 1000 g of Isopar G to obtain a liquid developer for electrophotography.

(Comparative Example 1) A liquid developer for electrophotography was obtained in the same manner as in Example 1 except that aluminum oxide octlate was omitted.

(Example 2) Rosin-modified maleic acid pentaerythritol ester (
Pentaline G manufactured by Rika Hercules) 60g Carbon black (Laben 1250 manufactured by Columbian Carbon) 1
2 g Aluminum oxide stearate (OLIP AOS manufactured by Hope Pharmaceuticals) 3 g Carrier liquid (Isopar H manufactured by Exxon Chemical Co., Ltd.) 125 g A mixture of these was used in the same manner as in Example 1 to obtain a liquid developer for electrophotography.

(Comparative Example 2) A liquid developer for electrophotography was obtained in the same manner as in Example 2 except that aluminum oxide stearate was omitted.

(Example 3) Coumaron-indene resin (S-Clone G manufactured by Nippon Steel Chemical Co., Ltd.)
90) 100g organic pigment (phthalocyanine blue) 12g aluminum oxide octrate (Olyp AOO manufactured by Hope Pharmaceutical Co., Ltd.)
) 8g Carrier liquid (Idemitsu Chemical Co., Ltd. IP Solvent 1620) 80g
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 aluminum oxide octlate was omitted.

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 intermediate transfer drum 50 is a hollow metal drum 5.
1 and an elastic layer 52 covering this. 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 intermediate transfer drum 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 by the charging device 2 and an exposure process by the exposure device 3. This electrostatic latent image is developed by a developing device 4 using a liquid developer. Development is performed by selectively adhering charged toner to the electrostatic latent image by electrophoresis, and a toner image is formed on the photoreceptor drum 1. Next, the intermediate transfer drum 50 and the photosensitive drum 1 are brought into contact with each other and an electric field is applied to transfer the toner image to the intermediate transfer drum 50. On the other hand, the recording paper 21, which is a recording medium, carried out from the paper feeding device 20 is transferred to the intermediate transfer drum 5.
It is conveyed to the contact position with 0. Pressure is applied by a pressure roller 40. Here, the toner image on the intermediate transfer drum 50 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 heat fixing device 10, where it is fixed by heat and pressure, and stored in the paper discharge tray 21-1.

[0025] With this recording method, general high-quality paper,
When bit image recording and character recording were performed on bond paper and PPC paper, it was confirmed that even better recording was possible than in the comparative example regardless of the type of recording paper.

[0026]

Effects of the Invention The liquid developer for electrophotography of the present invention has the effect that toner images with sufficient density and clear contours can be obtained on recording paper with small pressure, mainly in intermediate transfer type recording devices. has.

[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, which is soluble in the carrier liquid and has the following general properties. A liquid developer for electrophotography, characterized in that it contains aluminum oxide acylate represented by formula (I). General formula (I) (acyl-O-Al=)m (m=3-9
) However, in the above formula, acyl: CnH2n+1-CO- or CnH2n-1-CO- (n=8 to 18).