JPS6172278A - Cleaning roller - Google Patents

Abstract

PURPOSE:To repress a flaw on a drum surface of a photosensitive body to such a very minor extent that is not hardly affected on a sharpness or a contaminant of an image by coating with a cured silicone gum mixed a liquid silicone gum with specific dry silica powders as a filler on the cleaning roll. CONSTITUTION:The silicone gum usable to coat the cleaning roll is prepared by incorporating to the liquid silicone gum the dry silica powders having <=1mu a particle size as a reinforcing filler and then incorporating to the obtd. product <=3 Mohs hardness, preferably <=2 Mohs hardness filler e.g. 1-1.5 Mohs hard ness kieselguhr, 2-2.5 Mohs hardness borax as the filler which improves work ing performances such as a molding characteristic due to a thickness produced by compounding the dry silica powders and a grinding characteristic of the formed roll. The dry silica powders compounded to the silicone gum has <=1muC a particle size, thereby generating such very minor flaw as not to affect to the sharpness of the copied image, even if the flaw generates on the roll.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of the Invention The present invention relates to a cleaning roll that rotates and presses against a photoreceptor drum of an electrostatic copying machine to remove toner adhering to the surface thereof, particularly a cleaning roll coated with silicone rubber. This is related to the improvement of

``Prior Art'' Generally, cleaning rolls have a metal core coated with silicone rubber, or a metal core coated with sponge rubber and then silicone rubber coated on top. There is.

By the way, as silicone rubber, heat vulcanizable silicone rubber, room temperature vulcanizable silicone rubber, liquid silicone rubber, etc. are known.

Both room temperature vulcanizable silicone rubber and liquid silicone rubber are in a liquid state at room temperature.The former is cured at room temperature and becomes a cured product, while the latter is cured by applying heat. Although they are different in that vulcanization progresses to form a cured product, hereinafter both will be collectively referred to as liquid silicone rubber.

The liquid silicone rubber used in conventional cleaning rolls is made by homogeneously kneading polysiloxane with fillers, crosslinking agents, catalysts, pigments, etc. Pry silica (fumed silica) is added as a reinforcing filler.

When this dry silica is blended in a large amount, it becomes highly viscous, which impairs the formability during roll forming and the grindability with a grinder to obtain an appropriate surface roughness and uniform outer diameter as a cleaning roll. Along with formula silica, bulking fillers such as quartz powder and calcium carbonate are blended.

``Problems to be Solved by the Invention'' However, conventional cleaning rolls coated with silicone rubber have the problem of scratching the surface of the photoreceptor drum, making copied images unclear or smudged. Ta. The inventors of the present application conducted various research experiments regarding this problem, and as a result, it became clear that the cause of this damage is affected by the particle size and hardness of the filler added to the silicone rubber.

In order to solve the above-mentioned problems of the prior art, the present invention provides a coating silicone rubber vulcanizate on at least the surface layer of a cleaning roll by adding a coating silicone rubber vulcanizate to a liquid silicone rubber with a particle size of one pot or less. By mixing dry silica and powder with a Mohs hardness of 3 or less as an extended filler, scratches on the photoreceptor drum surface are kept to a very slight level that does not affect the clarity or stains of copied images. It is made to be moisturized.

The silicone rubber coating for the cleaning roll of the present invention is obtained by blending dry silica with a particle size of 1 unit or less as a reinforcing filler into liquid silicone rubber, and further improves moldability due to the thickening properties of this dry silica blend and the molded roll. As an extender filler to improve workability such as grindability, as a filler with a Mohs hardness of 3 or less, preferably 2 or less,
± (Mohs hardness 1-1.5).

It is made of a mixture of sand (Mohs hardness 2-2.5).

According to experiments conducted by the present inventors, the particle size of the dry silica used in silicone rubber is 1W or less, and the scratches on the surface of the photoreceptor drum are extremely small and do not affect the clarity of copied images at all. There was found. Most of the dry silicas currently on the market are IJ.
Any particle can be used since it has a particle size of L or less, and for example, Aerosil (trade name, manufactured by Nippon Aerosil Co., Ltd.) having a particle size of 50 to 70a+g can be used.

On the other hand, if an extender filler with a Mohs hardness of 3 or less, preferably 2 or less, is used, even if the particle size is greater than or equal to IJL and less than 10L, the photoreceptor drum will hardly be scratched and the clarity of the copied image will not be affected at all. It was also found that there was no effect. Such extender fillers include, for example, the trade name Radiolye) F
(manufactured by Showa Kogyo Co., Ltd.) and Celite (trade name, manufactured by Johnsman Building Co., Ltd.) can be used.

"Example" 1 to 25 parts by weight of Aerosil (trade name) as a reinforcing filler in liquid silicone rubber together with a predetermined amount of crosslinking agent, catalyst, etc.
A cleaning roll was formed using silicone rubber mixed and kneaded with 40 parts by weight of the trade name Radiolite F1 as an extender filler, and this was pressed against the surface of the photoreceptor drum.
After using the photosensitive drum for 100 hours, there were almost no scratches on the surface of the photosensitive drum, and the sharpness of the copied image did not change at all from before the use of the cleaning roll.

Claims (1)

[Claims] The coating silicone rubber vulcanizate on at least the surface layer of the cleaning roll is a mixture of liquid silicone rubber mixed with dry silica with a particle size of 1 μ or less and powder with a Mohs hardness of 3 or less as a filler. cleaning roll.