JPS60127238A - Preparation of cadmium sulfide for electrophotography - Google Patents

Abstract

PURPOSE:To prepare CdS for electrophotography not causing deterioration even if it is influenced by heat, by adding a proper amount of cation exchange resin to an aqueous solution of dispersed CdS, heat-treating the aqueous solution. CONSTITUTION:CdS powder having been subjected to given treatment such as calcination, etc. is crushed in the case of necessity, washed with water until impurities remaining on the surface are removed, the aqueous solution of dispersed CdS is blended with >=1ml/g cation exchange resin based on CdS particles, heated with stirring. After the blend is reached to a treatment temperature of >=40 deg.C, it is kept for about one hour at the temperature, to precipitate S on the CdS surface. The resin is separated from the CdS particles by filtration, the CdS particles are dried, to give CdS for electrophotography having no reduction in resistance caused by heating, no deterioration of optical damping characteristics resulting from previous history, not causing deterioration in properties due to environmental temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing cadmium sulfide for use in electrophotographic photoreceptors, and particularly to a method for producing cadmium sulfide that does not deteriorate even when exposed to heat.

Electrophotographic photoreceptors have various configurations in order to obtain predetermined characteristics or depending on the type of electrophotographic process to which they are applied. Typical electrophotographic photoreceptors include photoreceptors in which a photoconductive layer is formed on a support and photoreceptors in which an insulating layer is formed on the surface of the photoreceptor, which are widely used. The photoreceptor, which is composed of a support and a photoconductive layer, is most commonly used for image formation by (1) general electrophotographic processes, ie, charging, image exposure, development, and, if necessary, transfer.

In addition, for the photoreceptor with the 18# layer, this insulating layer can be used to protect the photoconductive electrode, improve the mechanical strength of the photoreceptor, improve the dark decay characteristics, or be applied in specific electrophotographic processes (further It is established for the purpose of eliminating pollution). Typical examples of electrophotographic processes using such a photoreceptor having an insulating layer or a photoreceptor having an insulating layer include, for example, U.S. Pat.
No. 15446, Japanese Patent Publication No. 1971-3713, Japanese Patent Publication No. 23910-1972, Publication of Equity Wa 43-24748, Japanese Patent Publication No. 19747-1974, Japanese Patent Publication No. 1974-4
No. 121, etc.

As a matter of course, a photoconductive material for electrophotography is required to have predetermined sensitivity electrical properties and optical properties depending on the electrophotographic process to which it is applied.

It is the main light guide (2) electrical material that determines the characteristics of a photoreceptor. General cadmium billion particles for electrophotography, which are often used as photoconductive materials, can be produced by controlling doping impurities, precipitation conditions during precipitation, firing conditions for diffusing impurities, and subsequent post-treatment conditions. Cadmium sulfide particles with desired properties are produced.

However, the properties of cadmium sulfide may deteriorate under the influence of heat. For example, under the influence of heat, a reduction in resistance occurs and a deterioration of optical attenuation characteristics due to pre-reflection, which will be described later, occurs.

The cause of these deteriorations is estimated to be that the Cd-8 bonds on the surface of the cadmium sulfide particles change due to heat, resulting in defects on the surface.
They begin to appear when heated above 150°C. After forming a photoconductive layer using the cadmium sulfide produced therein, high-temperature treatment should be avoided as much as possible, but treatment is often required depending on the configuration of the photoreceptor. For example, when forming a highly durable photoconductive layer by dispersing cadmium sulfide particles in a thermosetting resin, applying it to a wall, and then thermosetting it, a photosensitive layer with an insulating layer on the surface is used. There are cases in which the insulation layer is formed by covering the body with a thermosetting resin or a heat-shrinkable cylindrical film, or by bonding a resin film using a thermosetting adhesive. .

The main object of the present invention is to provide a method for producing cadmium sulfide that does not undergo the above-mentioned deterioration even when subjected to the influence of heat.

The method for producing cadmium sulfide according to the present invention is characterized by heating cadmium sulfide particles together with a specific cation exchange resin in a dispersion solution to precipitate sulfur on the surface of the cadmium sulfide.

As the cadmium sulfide used in the present invention, cadmium sulfide commonly produced as electrophotographic cadmium sulfide is appropriately used.

Cadmium sulfide for electrophotography can be produced by blowing hydrogen sulfide into an aqueous solution of a water-soluble cadmium salt such as cadmium sulfate containing donor and accenotor impurities to precipitate cadmium sulfide, followed by firing, or the method of manufacturing the present application. As in the method described in Japanese Unexamined Patent Application Publication No. 129825/1983, cadmium sulfide containing a donor is precipitated, and then the cadmium sulfide is mixed with a fluxing agent at a temperature higher than the melting point of the fluxing agent. There is a method of manufacturing by firing at a temperature higher than 0.degree. C. and then re-firing, but in any case, a firing step is necessary in order to use it for electrophotography. It is effective to perform this treatment after the final firing step is completed.

The amount of cation exchange resin added is 17! for 1 g of cadmium sulfide to be treated. It must be added in the above proportion. The amount added is related to the processing temperature; if the temperature is low, it is preferable to increase the amount added relatively, and the processing temperature is preferably 40°C or higher; below this, even if the amount of resin is increased. , the treatment effect decreases.

The processing time has less influence on the characteristics than the temperature, but even if the processing time is increased by one hour or more, the characteristics are hardly affected. If the treatment time is less than 1 hour, the reproducibility will deteriorate especially if the treatment time is short, so it is preferable to use a treatment time of at least (5) approximately 1 hour.

In the above-mentioned treatment method of the present invention, the fired powder is dismantled as necessary, washed with water until most of the impurities remaining on the surface are removed, and then subjected to cation exchange. After adding the required amount of resin, it is heated and stirred, and after reaching the processing temperature, the temperature is maintained for approximately 1 hour. Next, the resin is separated, filtered, and dried to obtain cadmium sulfide for electrophotography.

The cadmium sulfide obtained in this way has a lower resistance than cadmium sulfide that appears when heated, does not cause deterioration of optical attenuation characteristics due to pre-reflection, and also prevents deterioration of characteristics due to ambient temperature.

Pre-reflection refers to the fact that when a photoreceptor is created, the resistance of the photoconductive layer changes depending on the storage conditions, that is, whether or not it is irradiated with light during storage, and it also affects the light attenuation characteristics. It is about giving.

Conventionally, such front markings have not been a problem, but in order to improve the quality of copied images, a process for erasing the front markings has become necessary.

(6) That is, in the electrophotographic process of high-speed copying, it is effective to perform pre-exposure before fluorescent light in order to erase the tint formed by the previous process.

When such pre-exposure is performed, the resistance of cadmium sulfide itself is very high, and the light attenuation characteristics do not change and are rapid regardless of storage conditions.

The cadmium sulfide according to the invention is particularly unique in this respect.

Example 1 Using cadmium sulfate and copper sulfate as starting materials, sulfuric acid and
Hydrogen sulfide was blown into an aqueous solution containing hydrochloric acid to precipitate cadmium sulfide.

100 g of the fluidized cadmium was calcined at a temperature of 50° C., then transferred to a 5 Jl beaker, and dissolved by adding 21 of pure water. After adding pure water to make 51, the supernatant of the dispersion was decanted by the decantation method. Washing with water was repeated until the conductivity became 5 μl/Cm or less. After adding cation exchange resin (SK-1B manufactured by Mitsubishi Kasei) 200- to this cadmium sulfide, the liquid temperature was maintained at 50° C. and stirring was continued for 1 hour. After separating the resin, it was filtered and then heated at a temperature of 60° C. overnight.

This cadmium sulfide was uniformly mixed and dispersed with CBR resin (cyclo-butadiene rubber, manufactured by Japan Synthetic Rubber Co., Ltd.), and then coated on an aluminum substrate to a thickness of 40 μm. After heating this photosensitive plate at 180°C to harden the resin,
A 25μ polyester film was applied as an insulating layer.
A photosensitive plate having a 3I-configuration was prepared.

Example 2゜Example 1. 20.0 g of cact2 was added to 100 gr of cadmium sulfide precipitated in the same manner as above. 30g of Lit and NaCt were added, mixed well, and then filled in a quartz mold and fired at 530°C for 30 minutes (note that CdCl2 and NaCt
From the phase diagram, the melting point of the mixed flux of Ct is cact2・2N
aCt melting point of 426°C). The temperature of 60,000 degrees Celsius of the cadmium sulfide obtained in this way is 100%, and according to an electron micrograph at 10,000 times magnification, the particle surface is extremely smooth and has a unique hexagonal shape, and each particle is Single particles with a diameter of 2 to 5 μm were observed.

Next, the cadmium sulfide thus obtained was heated to 450°C.
Re-fired for 1 hour.

After re-firing, it was dismantled, and then water washing was repeated using the decantation method until the conductivity of the supernatant liquid of the dispersion became 5 μs / crs or less, and after adding 110% of a cation exchange resin (PK2Q4 Mitsubishi Kasei), Stirring was continued for 1 hour while the mixture was boiling.

After separating the resin, it is filtered and then heated at a temperature of 60 °C for 1
It was heated overnight. This cadmium sulfide was prepared in Example 1. It was made into a photoconductor in the same manner as above.

Comparative example 1. ~2゜Example 1. ~2. Cadmium sulfide was produced in the same manner as in Example 1 except for the step of adding a cation exchange resin and heating. A photoreceptor was prepared in the same manner as above.

One photoreceptor of each of the above four examples was left under light irradiation,
The other sheet was left in a dark place and the following measurements were made to compare the effects. The measurement was carried out using the measurement device (9) shown in the drawing.

That is, the glass plate 3 having the transparent electrode 4 was pressed against the insulating layer surface of the photosensitive plate 9. The transparent electrode 4 is connected to a high voltage DC power source 6 via a relay switch 5.

The measurement is performed by closing the relay switch 5 for 0.2 seconds and setting the high pressure (
Apply Va) and leave it for 0.2 seconds (oven) to turn off the light to 0.
．． The irradiation was performed for 2 seconds, and the voltage change (Vp) at that time was measured using a metal plate 7 and a surface electrometer 8, which were at the same voltage as the photosensitive plate.

Note that vp is the voltage applied to the photoconductive layer.

Furthermore, as a pre-exposure, white light from the Halodan lamp 1 was irradiated onto the shutter 2 for 0.2 sec, and after leaving it for 0.2 sec, VA was applied, and after leaving it for 2 sec, the light was applied again for 0.2 sec.
Irradiation was performed for 2 seconds and the voltage change vp' at that time was measured.

Vp and vp when Va is -2000V /Measure the value of Vp when Va is +2000V
a: OVP when applying -2000V The speed of optical attenuation was determined from -VP'.

Regarding the photoreceptors manufactured in Example 1.2 and Comparative Examples 1 and 2, the results were as follows: (10) Va. : Vp at -2000V
.

Va: Vp and Va when +2000V:
The results of measuring Vp -ypZ at -2000V were as follows.O Example 1. Comparative example 1. and Example 2. Comparative example 2. When comparing the values of ``I'' and ``P'' of the example, it is smaller than that of the comparative example. This means that the speed of light attenuation is faster for the photosensitive plate of the example, and that This shows that there is little difference in the speed of light attenuation due to redirection, and that the effect of heating during the formation of a photosensitive plate is almost non-existent in the case of the example.

In addition, when applied to a copying machine to produce an image based on the basic process of pre-exposure, -second fluorescence, and simultaneous AC exposure and full-surface irradiation, when the photoreceptor of the comparative example was used in a box, it was left in a dark place for a long time. Afterwards, a phenomenon that the image became thinner appeared, but when the photoreceptor of the example was used, a good image was maintained even after being left standing. If you let
In the photosensitive plate of the comparative example, the resistance became lower and the image density decreased as the temperature went lower, whereas in the photosensitive plate of the example, there was almost no change.

[Brief explanation of drawings]

The drawing shows an apparatus for measuring the photosensitive characteristics of a photoreceptor. 4: Transparent electrode, 5: Relay switch, 6: High voltage DC power supply, 7: Metal plate, 8: Surface electrometer, 9: Photosensitive plate. Engraving of the drawings (no change in content) Figure 1 Procedural amendment r8 parfait, case display Showa 2 in hand Relationship with permission application No. 23 Taku No. 92 case Applicant 1 person, 1 residence, 1 territory → - 1 name (Name) Anaya/Nfusho aA 7±4, Agent address: 3301 Gen 1, Shigesu Building, 2-6-2 Marunouchi, Chiyoda-ku, Tokyo, 3301 Gen 1 Riki 8, Contents of amendment Amendment as shown in the attached document. Written procedural amendment 1, Indication of the case Showa Iz year patent application in hand; Note 1. On the bottom line of page 9, the words ``shown in the drawings'' should be corrected to ``shown in Figure 1.'' 2. On page 12, line 14, ``The drawing is'' is corrected to ``Figure 1 is''.

Claims (1)

[Claims] 1. A method for producing cadmium sulfide for Seiko photography, which comprises adding a cation exchange resin to the particles in an aqueous cadmium sulfide dispersion solution at a ratio of 1 g/g or more, followed by heat treatment.