JPS5960460A - Electrophotographic clearing liquid - Google Patents

Abstract

PURPOSE:To obtain a clearing liquid which removes stain due to a toner developer which is extremely hard to remove, by making an electrophotographic clearing solvent to contain a nonpolar organic solvent and a polar organic solvent. CONSTITUTION:A representative nonpolar organic solvent is paraffin hydrocarbon, specially, isoparaffin hydrocarbon which is the insulating solvent of a wet type developer. A reprsentative polar organic solvent is alcohol such as methyl (ethyl, propyl) alcohol, ester such as acetate (ethyl, butyl) isoacyl, and ketone such as acetone and methyl ethyl ketone. The mixing rate of those both solvents is decided by considering the clearing effect of the clearing solvent, compatibility between both solvents, evil influence upon an electrophotographic characteristic at the time of the mixing with the developer, etc., but the range extending 10-80wt%, preferably 20-60wt% polar solvent based upon the sum of both solvents is normally used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cleaning liquid for an electrophotographic developing machine, and more particularly to a cleaning liquid suitable for cleaning a developing machine used in plate making of wet electrophotographic printing plates.

A lithographic printing plate obtained by applying electrophotography is usually a lithographic plate in which a photosensitive layer made of a photoconductive powder such as zinc oxide dispersed in an insulating resin binder is provided on a conductive support. Printing plate materials are obtained by forming an ink-receptive toner image on a photosensitive layer by a process of charging, exposure, toner development and fixing. As another method, a lithographic printing plate material having an insulating photosensitive layer containing an organic photoconductive compound on a conductive support such as an aluminum plate having a hydrophilized surface is charged, exposed to light, and coated with toner. After development and fixing, a lithographic printing plate is obtained by etching away non-image areas other than toner image areas and exposing the hydrophilic surface of the support.

Toner development of lithographic printing plates obtained using these electrophotographic methods includes a dry development method in which charged toner particles are scattered, and a wet development method in which a developer in which charged toner particles are dispersed in an insulating liquid is used. A wet developing method is often used because it has excellent toner image resolution and image reproducibility.

When toner development as a plate-making process is repeated for a long time, dirt such as dirt and dust accumulates in the developing device, and toner particles adhere to the developing device, reducing plate-making performance. Washed. As the cleaning liquid, an insulating liquid that is a dispersion medium for a developer, such as an inoparaffin hydrocarbon, is usually used.

These developer dispersion solvents are used because they do not adversely affect the properties of the developer even if they are mixed with the developer after washing, and although they have a cleaning effect on normal stains, 1. There is a drawback that it is very difficult to remove the heavily soiled parts of the developer squeezing roller and the like, and once the stains have dried.

An object of the present invention is to provide an electrophotographic cleaning liquid that has excellent cleaning power and can remove the stains caused by toner developer which are extremely difficult to remove.

It has been found that the object of the present invention can be achieved by providing an electrophotographic cleaning liquid containing a nonpolar organic solvent and a polar organic solvent.

Typical nonpolar organic solvents used in the present invention are:
Paraffinic hydrocarbons, which are insulating solvents for wet developers;
Especially isoparaffinic hydrocarbons.

Typical polar organic solvents used in the present invention include alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol, esters such as ethyl acetate, butyl acetate, and inamyl acetate, and ketones such as acetone and methyl ethyl ketone. It is something.

The mixing ratio of the nonpolar organic solvent and the polar organic solvent is determined as appropriate, taking into consideration the cleaning effect as a cleaning liquid, the compatibility of both solvents, and whether there is any adverse effect on the electrophotographic properties when mixed in the developer. Usually the polar solvent is in the range of 10 to 80% by weight, preferably 20 to 60% by weight of the sum of the nonpolar solvent and the polar solvent.
Used within the range of

Although the cleaning liquid of the present invention is effective as a cleaning liquid for electrophotographic developing devices, it can be used not only for cleaning the developing device but also for cleaning stains in various parts caused by toner developer.

Since the polar organic solvent according to the present invention has a high dielectric constant (approximately 4 or more), when mixed into a toner developer, it impairs the insulation properties of the developer, thereby adversely affecting electrophotographic properties. Therefore, after cleaning the developing device, it is necessary to prevent it from remaining in the developing device as much as possible, but some amount of contamination is unavoidable. Even if the above esters in polar organic solvents are mixed into the toner developer,
It is preferable because it has less adverse effect on electrophotographic properties than other solvents.

Although the cleaning liquid of the present invention can be used in various electrophotographic methods, it is particularly useful for cleaning a developing device for a lithographic printing plate using a wet development method in which stains of toner developer are difficult to remove.

The effects of the present invention are mainly that adhesive substances (e.g., organic polymer compounds) contained in the developer composition fixed in the developing device etc. are dissolved by the polar solvent, and the cleaning action of the non-polar solvent and the dust are combined with each other. This seems to be because it is removed along with other dirt and dust.

Next, examples of the present invention will be described, but the present invention is not limited thereto.

Example 1 A lithographic printing plate material having a zinc oxide-resin electrophotographic photosensitive layer on conductive-treated waterproof paper was repeatedly subjected to corona charging, image exposure, and toner development by wet development to form a lithographic printing plate. The board was made into a plate. After the plate-making process, when the developing device was left to dry without being cleaned, toner and dirt stuck to various parts of the developing device that came into contact with the toner developer.

I rubbed the parts of this developing device where toner and dirt had adhered many times with a cloth soaked only in isoparaffinic hydrocarbon, which is a conventional cleaning solution, but nothing could be removed. In contrast, isoparaffinic hydrocarbon and ethyl acetate were mixed in a ratio of 1:1.
When rubbed with a cloth dipped in the cleaning solution of the present invention mixed in the proportion of However, there was no adverse effect on the electrophotographic properties.

Example 2 In Example 1, similar results were obtained when a composition liquid in which isoparaffinic hydrocarbons, methanol, and butanol were mixed in a ratio of 2:2:1 was used as the cleaning liquid of the present invention.

Example 3 In Example 1, similar results were obtained when a composition liquid in which Itsubarafin' hydrocarbon and methyl ethyl ketone were mixed at a ratio of 1.1 was used as the cleaning liquid of the present invention.

In the above examples, the isoparaffinic hydrocarbons include Shellzuru 71 manufactured by Shell Oil Co., Ltd., IP Solvent 1620 manufactured by Idemitsu Petrochemical Co., Ltd.,
Various products such as Isopar G and Isopar 11 manufactured by Esso Oil Co., Ltd. can be used.

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Claims (1)

[Claims] An electrophotographic cleaning liquid characterized by containing a nonpolar organic solvent and a polar organic solvent.