JPS60208760A - Manufacture of electrophotographic sensitive fluid - Google Patents

Abstract

PURPOSE:To form a photosensitive layer superior in mechanical strength by dispersing a photosensitive fluid essentially consisting of an electrostatic charge transfer medium and a charge generating pigment by using a dispersing machine composed of a vessel and a ball mill both made of alumina. CONSTITUTION:A photosensitive fluid is prepared by mixing 12pts.wt. of N,N'- di(3,5-dimethylphenyl)perylene-3,4,9,10-tetracarboxylic acid diimide, 100pts.wt. of poly-N-vinylcarbazole, 10pts.wt. of a polyester resin ''Bairon 200'' made by TOYO BOSEKE KK, and 150pts.wt. of tetrahydrofuran, and alumina balls are placed into a mill pot made of alumina in an apparent volume of 200ml, and 100ml of said fluid mixture is introduced, and dispersion operations are executed at a revolution of 70rpm for 6, 12, 24, 45hr to prepare 4 kinds of photosensitive fluids. They are applied to aluminum plates each 80mum thick with a wire bar so as to form each 14mum dried thickness, and dried at 100 deg.C for 1hr to form photosensitive plates. The pencil hardness of the obtained plates are 3H in the cases of >=12hr drying times, and it is found in actual tests to have superior mechanical strength as compared with the case of 2H obtained by using an ultrasonic dispersing machine.

Description

[Detailed description of the invention] (Technical field) The present invention relates to a method for producing a photosensitive liquid for electrophotography.

(Prior Art) In order to obtain clear electrophotography, electrophotographic photosensitive liquids must be uniformly charged. For this purpose, it is essential that the photosensitive layer be formed on the surface of the conductive substrate to be smooth and to have a uniform thickness. Various inorganic and organic photosensitive materials are known for forming photosensitive layers. Among them, photosensitive layers containing charge-generating pigments and charge-transporting media as main components are prepared using a ball mill or the like in the preparation of photosensitive liquids. Measures have been taken to pulverize particles such as pigments into fine particles. The photosensitive layer described above has poor mechanical strength compared to inorganic photosensitive layers. Conventionally to increase its strength.

For example, silica and carbon tetrafluoride with a diameter of 1 μm or less.

Inorganic fine powder particles such as alumina are mixed into the photosensitive layer as reinforcing powder. As a method for dispersing the fine powder particles into the photosensitive layer, a method is adopted in which the fine powder particles are mixed in at the stage of prescribing and weighing the photosensitive liquid, or mixed in a dispersion liquid in which the fine powder particles are dispersed in advance. Since the fine powder particles mixed are in a very small amount, less than 1% of the photosensitive liquid (1), uniform dispersion in the photosensitive liquid is very difficult, and the fine powder particles tend to be localized within the photosensitive layer. Also, in this way? A photosensitive liquid mixed with AJ'A particles tends to cause aggregation during the photosensitive layer formation stage, which makes the surface of the photoreceptor rough.

(Object of the Invention) An object of the present invention is to provide a method for producing an electrophotographic photosensitive liquid that can form a photosensitive layer with excellent mechanical strength without introducing fine powder particles for reinforcing the photosensitive layer from the outside. Another object of the present invention is to provide a method for producing a photosensitive liquid that can form a homogeneous and smooth surface of a photosensitive layer.

(Structure of the Invention) The method for producing a photosensitive liquid for electrophotography of the present invention uses a dispersing machine comprising an alumina container and an alumina ball to disperse a photosensitive liquid mainly containing a charge transport medium and a charge generating pigment. It encompasses things.

Thereby, the above objective is achieved.

The dispersing machine used in the present invention needs to be a ball mill dispersing machine consisting of an alumina container and an alumina ball. There are no particular restrictions on its configuration. In this ball mill dispersion machine, ultrafine alumina particles generated by the collision of the holes with the container wall are mixed into the photosensitive liquid, and these serve as fine powder particles for reinforcing the photosensitive layer. The alumina used in the container and bowl is sintered and is therefore very strong. Therefore, if either the container or the ball is made of a material other than alumina, either of them will be destroyed and the desired alumina fine particles will not be generated, making it impossible to achieve the effects of the present invention.

In order to efficiently disperse the photosensitive liquid, it is preferable that the apparent volume of the balls be 50% of the internal volume of the ball mill container, and that the dispersion liquid be 15 to 30% of the internal volume.

Furthermore, the suitable rotation speed N (rPm) of the ball mill dispersion machine
depends on the inner diameter R of the container and is determined by the following equation (1).

N - (37-3, 3R) /fF ... (1) (R
2 (according to 11) For example, when using a disperser with an inner diameter of 13 cm, the rotation speed can be calculated as 70 rpm.

In the present invention, by carrying out dispersion between 12 and 24 hours under the above conditions, pigment particles and the like are suitably dispersed, and a desired amount of fine alumina particles are mixed into the photosensitive liquid and dispersed. Ru. The mechanical strength of a photoreceptor formed using this photoreceptor increases. Furthermore, there is no adverse effect on the electrical characteristics of the photoreceptor. When the dispersion time is less than 12 hours.

Dispersion of the photosensitive liquid is insufficient, and the amount of alumina fine powder particles to be mixed is small. Therefore, when this dispersed photosensitive liquid is used to make a photoreceptor, the residual potential of the photosensitive liquid increases and the sensitivity decreases. If the dispersion time exceeds 24 hours, an excessive amount of alumina fine powder particles will be mixed into the 3 dispersion liquid. This becomes a contaminant and adheres to the surface of the photoreceptor, causing an increase in residual potential.

It also reduces the sensitivity of the photoreceptor.

As photosensitive liquids, all kinds of dispersions for organic photoconductor photosensitive layers can be used. Photosensitive layers include functionally dispersed organic photosensitive layers, which have a charge-generating pigment layer on the surface of a conductive substrate and a charge-transporting medium layer thereon, and functionally dispersed organic photosensitive layers, which have a charge-generating pigment layer on the surface of a conductive substrate and a charge-transporting medium layer thereon, as well as functionally dispersed organic photosensitive layers in which a charge-generating pigment layer is disposed on the substrate surface and a charge-transporting medium layer. There is an organic photosensitive layer provided with a body layer.

Examples of charge-generating pigments include perylene pigments, quinacridone pigments, pyranthrone pigments, phthalocyanine pigments,
Photoconductive organic pigments such as disazo pigments and trisazo pigments are used. As the charge transport medium, a charge transport resin such as polyvinylcarbazole or other resins which do not themselves have photoconductivity may be used, such as polyester resin.

A combination with an epoxy resin, a polycarbonate resin, an acrylic resin, etc., or a resin in which a low-molecular charge transport medium such as a hydrazino group Bn & form or a pyrazoline type derivative is dispersed is used.

(Example) The present invention will be described below with reference to examples.

N,N'-di (3,5-cymethy1tophenyl) perylene-3,4,9,10-tetracarnene 1 unit diimide 12ffiffi part Poll-N-vini 11 carbacy + L 100 duet 1 part Bo 9 'L Ste 11 resin(
Buy-un 200. 10 parts by weight of tetrahydrofuran (manufactured by Toyobo Co., Ltd.) and lsomi parts of the above formulation were mixed. Next, put an apparent volume of 200 ml of alumina balls into an alumina millbot (inner diameter 3 cm, internal volume 400 m), and then add 100 ml of the above mixed solution.
j2 was added for dispersion. The dispersion is 1 at a rotation speed of 7 Orpm.
Four types of photosensitive solutions were prepared by changing the dispersion time to 6, 12, 24, and 45 hours.

Each of the above photosensitive solutions was coated onto an 80 μm thick aluminum plate using a wire bar so that the dried thickness would be 14 μm, and dried at 100° C. for 1 hour to obtain a photosensitive plate.

The electrostatic properties (charge amount, residual potential) and surface hardness (pencil hardness measurement method: according to JIS K 5400) of this photosensitive liquid were measured.

The results are shown in the table.

The electrostatic properties were measured using an electrostatic paper analyzer (manufactured by Kawaguchi type iKK).

Comparative Example Instead of dispersing the undispersed liquid mixture using a ball mill, an ultrasonic dispersion machine was used to perform dispersion for 150 (5 ec), and a photosensitive plate was produced in the same manner as in the example.

When each measurement was carried out in the same manner as in the example, the surface potential was 600.
(V), the residual potential was 100 (V), and the pencil hardness was 2H.

(Effects of the Invention) According to the method of the present invention, a photosensitive liquid capable of forming a photosensitive layer with excellent mechanical strength can be obtained simply by using an alumina ball mill dispersion machine and driving it for a predetermined period of time. . Since the surface of the photosensitive layer formed with this photosensitive liquid is homogeneous and smooth, excellent electrophotography can be provided.

Applicant: Sanda Kogyo Co., Ltd. Agent: Patent Attorney Shusaku Yamamoto

Claims (1)

[Claims] 1. A photosensitive liquid for electrophotography, which involves dispersing a photosensitive liquid mainly containing a charge transport medium and a charge-generating pigment using a dispersing machine comprising an alumina container and an alumina ball. Production method. 2. In the dispersion process, when the inner diameter of the alumina container of the dispersion machine is R9 and the rotary plate is N (rpllll), N = (
37-3,3R)/(W) for 12 to 24 hours. 3. The charge transport medium is a polyvinylcarbazole resin. The manufacturing method according to claim 1. 4. The manufacturing method according to claim 1, wherein the charge-generating pigment is a perylene pigment.