JPS60127237A - Preparation of cadmium sulfide for electrophotography - Google Patents

Abstract

PURPOSE:To prepare CdS having high sensitivity, providing high-quality images, by adding a proper amount of flux consisting of NaCl/CdCl2 to CdS containing a specific amount of Cu, calcining the prepared blend, heating it with Cu, sulfur compound, etc. in water. CONSTITUTION:CdS containing 4-10X10<-4>mol Cu based on 1mol CdS is blended with a mixed flux consisting of NaCl/CdCl2 in such a way that an amount of CdCl2 is 5-15mol%, the prepared blend is calcined in a temperature range from the melting point of the flux to a temperature 50 deg.C higher than it, to give a calcined material consisting of CdS particles having simple and small particle diameters. The calcined material is dispersed into water, crushed, blended with proper amounts of Cu and a compound such as thiourea, etc. to generate sulfur by heating, and heated at about 80 deg.C. Consequently, uniform one layer is precipitated on the surface of the CdS particles having small particle diameters to give CdS for electrophotography having raised uniformity of particle surface, improved resolving power, providing high-quality images, having improved durability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing cadmium sulfide for electrophotography, and in particular, it relates to a method for producing cadmium sulfide for electrophotography. This relates to a manufacturing method.

One method that has been put into practical use to produce cadmium sulfide powder used in electrophotographic photoreceptors involves blowing hydrogen sulfide gas into an aqueous cadmium solution containing impurity elements such as copper to precipitate cadmium sulfide. Fluxing agents such as cadmium chloride are added to increase grain growth and improve crystallinity of the powder.

In particular, when the amount of flux is at least 20% by weight of the cadmium sulfide powder and the waste acid temperature is 950°C or more higher than the melting point of the flux, the shape of the cadmium sulfide powder becomes extremely simple. A highly crystalline product is obtained, and an electrophotographic photoreceptor using this material exhibits excellent properties.

The properties for electrophotography, especially the sensitivity, are determined by the surface impurity concentration of the cadmium sulfide particles and the interparticle barrier factor.

On the other hand, in order to obtain high-quality images, it is generally advantageous to reduce the particle size of the particles. However, if the particle size is reduced, the number of barriers between particles increases and sensitivity decreases. Furthermore, sensitivity varies widely for small changes in particle size.

For this reason, conventionally it has not been possible to reduce the grain size of the residual particles.

The present invention provides a method for producing cadmium sulfide that does not reduce sensitivity while reducing particle size.

The present invention attempts to compensate for the decrease in sensitivity due to an increase in the number of interparticle barriers by depositing a further surface layer on the surface using cadmium sulfide having a small particle size.

The present invention is a method of improving the photographic properties of the surface layer by depositing a surface layer, so by increasing the resistance of the bulk of the particles, which does not affect the properties, durability is improved as an additional effect. can also be increased. That is, the gist of the present invention is that 4 to 10XIO per mole
A mixed flux consisting of sodium chloride/cadmium chloride is added so that the additive amount of cadmium chloride becomes 5 to 15 moles to cadmium sulfide containing moles of copper, and the mixture is heated to 50°C from a temperature equal to the melting point of the flux. This is a method for producing cadmium sulfide for electrophotography, which comprises firing at a high temperature, then dispersing it in water, adding copper and a compound that generates sulfur when heated, and heating.

In the specific method of the present invention, a mixed flux is added to cadmium sulfide containing a specific copper in advance, and the mixture is fired at a temperature selected from a temperature equal to the melting point of the flux to a temperature 50°C higher. 1. Create particles with a small particle size. This fired product is
After being dispersed in water, an appropriate amount of copper and a substance that generates sulfur upon heating are added and then heated. By this operation, cadmium sulfide containing copper and chlorine is precipitated on the surface of cadmium sulfide. The reaction using a sulfur-generating substance is important in order to cause the precipitation reaction to occur slowly, so that a uniform layer can be deposited on the surface of small particles as in the case of the present invention. It is.

Furthermore, precipitating the surface layer has the effect of further increasing the uniformity of the particle surface.

The flux used in the present invention is a mixed flux of IJium chloride/cadmium chloride.The composition and amount of the flux are selected so that cadmium chloride is 5 to 15 mole% relative to cadmium sulfide. There must be.

If the amount of chlorine is too large, the resistance will be too low, and if it is too small, the amount of donors will not be large enough to compensate for the barrier. In fact, it is most effective when the chlorine concentration is in the range of 0.1 to 0.4 (mol/!).

The amount of washing water after firing cannot be reduced too much from the viewpoint of washing efficiency, and from the viewpoint of subsequent reactions, it is disadvantageous to increase the amount of water. The optimal water cover for washing is about 2 Ai per 100 gr of cadmium sulfide. As a result of washing with this amount of water, the amount of chlorine present is in the range of 0.2 to 0.8 mol.

The reason why cadmium chloride is selected from the range of 5 to 15 moles relative to cadmium sulfide is based on the thickness of the surface layer to be deposited.If it is less than 5 moles, the thickness of the surface layer is thin, so It is disadvantageous because it is affected by the no.
Moreover, if the particle size exceeds 15 molt, the growth of the particle size itself becomes a problem, and the effect of making the particle size small in advance is lost.

Cadmium chloride in the flux is used as a deposit forming material.

From the above results, Figure 1 shows the preferred NaC mixed flux.
The range of the 2/CdCl2 mixing ratio and addition amount is illustrated in (5).

From FIG. 1, it can be seen that as the ratio of cadmium chloride increases, the latitude of the amount added becomes gradually narrower. The latitude of the addition amount is wide when the ratio of cadmium chloride in the mixed flux is 0.1 to 0.3. When the amount of flux added is increased, particle size growth is less likely to occur even if firing is performed at a high temperature, that is, around a temperature 50°C higher than the melting point of the flux. This is more advantageous because it is easier to form a single particle. Furthermore, the larger the amount of flux, the wider the latitude with respect to the firing temperature, which is also advantageous in this respect.

In areas with a large amount of cadmium chloride, the amount of cadmium chloride in the residual flux is close to 15 molty, so calcination must be performed near the melting point to prevent particle growth as much as possible.

After firing, the fired product is dispersed in water and then dismantled. Next, a substance that generates sulfur when heated and steel are added, water is further added to bring the total amount to 21, and then heated.

After reaching 80° C., heating was continued for 60 minutes, then heating was stopped (6) and washing was repeated by decantation until the conductivity of the supernatant became 20 μs/an. In order to remove impurities remaining on the particle surface, a cation exchange resin and an anion exchange resin are further added and stirred for 60 minutes. After separating the resin, it is filtered and dried at a temperature of 60° C. overnight. After the resulting powder is fired again, cadmium sulfide particles are created using the same operations as after firing.

The cadmium sulfide used during the first firing is 4 x 10 to 10 x 1 copper per mole of cadmium sulfide to increase durability.
Contain 0 mol.

On the other hand, the amount of copper used during surface layer precipitation ranges from 1 to 3 x 10 moles per mole of cadmium sulfide produced.
It is preferable to determine the concentration in consideration of the chlorine concentration present in the solution.

As substances that generate sulfur when heated, thiourea, thiosulfate, IJum, etc. are excellent. Since the rate of the decomposition reaction is not very fast, it is preferable to add about twice the amount required in order to completely react the remaining cadmium.

Since the photoreceptor made using the cadmium sulfide particles prepared as described above has a small particle diameter, it is possible to obtain a high-quality image with good resolution, and it also has excellent durability.

This will be explained below using examples.

Example 1 Cadmium sulfide 10 containing 6 x 10 moles of copper per mole
13.0 gr of cadmium chloride + 37.0 gr of sodium chloride were added to 0 gr, mixed well, and then filled in a quartz mold and fired at 470°C for 60 minutes. (In addition, the melting point of the mixed flux of sodium chloride and cadmium chloride corresponds to 426°C at this mixing ratio.) After cooling, it is dismantled, and 1.8 x 10" moles of copper and 0 mol of sodium thiosulfate are added.
．． After adding 15 moles, water is added until the total amount becomes 2 tons. This aqueous dispersion solution is heated while stirring, and after reaching 80°C, heating is continued for an additional 60 minutes. Thereafter, washing is repeated until the conductivity of the supernatant liquid becomes 20 μs/cm or less, and then 2 SnLt each of a cation exchange resin and an anion exchange resin are added and stirred for 60 minutes. After separating the resin, it was filtered and dried at 60° C. overnight.

This cadmium sulfide was filled into a quartz tube and refired at a temperature of 450° C. for 60 minutes. Thereafter, water washing and deionization treatment were performed until the electrical conductivity of the washing liquid became 1.0 μm/c1n or less, and after dehydration, it was dried at 60° C. for 24 hours. The temperature of 60,000 degrees Celsius of the cadmium sulfide obtained in this way was 100%, and when observed under an electron microscope (10,000 times magnification), the particle surface was extremely smooth and had a unique hexagonal crystal shape. It was observed that the particles were a single particle with a diameter of 1.0 to 2.0 μm.

This cadmium sulfide was mixed with vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by UCC).
The film was coated on an aluminum substrate to a film thickness of 40 μm, and after drying, a polyester film (trade name: Mylar, manufactured by Diafoil) with a thickness of 25 μm was applied thereon to prepare a measurement sample.

Example 2. ~3゜To cadmium sulfide containing copper in the amount shown in the table, a mixed flux having the mixing ratio shown in the table is added, and after firing, the substances that generate copper and sulfur are shown in the table (9). Example 1. After processing in the same manner as in Example 1. A photosensitive plate was prepared in the same manner as above.

Example 1. ~3. The sensitivity of the photosensitive plate was measured using the measuring device shown in FIG.

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.

(10) The measurement was performed using Halodan Lang 1 white light at 7'r as a pre-exposure.
Irradiated p 0.2 sec to Ytar 2, 0.2 ge
After leaving it as it is, close the relay switch 5 for 0.2 seconds and apply high voltage (Va), release it for 12 seconds, irradiate it with afterlight for 0.2 seconds, and change the voltage at that time (vp).
was measured using a metal plate 7 at the same voltage as the photosensitive plate and a surface electrometer 8. Note that vp is the voltage applied to the light guide layer. Sensitivity is determined by setting the voltage Va in advance so that Vp is 600v, irradiating light at the same time, measuring the change in υVp by changing the exposure amount, and calculating the E-V curve from this curve. The exposure amount was obtained.

The results are shown in the table below.

From this result, it can be seen that the directivity is similar to that of the conventional method. Furthermore, this photosensitive plate is firstly charged, and then photoimage exposure AC
When a high-speed electrophotographic process of static elimination and then full-surface exposure was applied, high-quality images with sufficient electrostatic contrast and sufficient sensitivity were obtained. In particular, the resolution was 10 lines/W or more, and sharp images were obtained.

Furthermore, when the above-mentioned copying machine was used for repeated durability 200,000 times, the retention rate of the electrostatic contrast after durability against the initial electrostatic contrast was as shown in the table, indicating that the durability was good. .

[Brief explanation of drawings]

FIG. 1 shows the relationship between the ratio of the mixed flux and the amount added, and the shaded area shows the range that can be used in the present invention. FIG. 2 is a diagram showing an apparatus for measuring the sensitivity of a photoreceptor. 4: Transparent electrode, 5: Relay switch 6: High voltage DC power supply, 7: Metal plate, 8: Surface electrometer, 9: Photoreceptor. Figure 1 5. Mole i of sum p &JF'l, ratio Figure 2

Claims (1)

[Claims] A mixed flux consisting of sodium chloride/cadmium chloride is added to cadmium sulfide containing 4 to 10XIO mol of copper per mol so that the amount of cadmium chloride added is 5 to 15 mol, and the melting point of the flux is from a temperature equal to 50℃
A method for producing cadmium sulfide for electrophotography, which comprises firing at a high temperature, then dispersing it in water, adding copper and a compound that generates sulfur when heated, and heating.