JPS60127236A - Preparation of cadmium sulfide for electrophotography - Google Patents

Abstract

PURPOSE:To prepare CdS having improved sensitivity of long wavelength and high-quality image, by blending CdS containing a specific amount of Cu with a mixed flux consisting of NaCl/CdCl2, calcining the prepared blend, heating it with Cu, In, 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%, it is calcined in a temperature range form 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, blended with Cu, In and a compound such as sodium thiosulfate, etc. to generate S by heating, and the blend is heated at about 80 deg.C. Consequently, one layer of CdS containing Cu, In, and Cl is uniformly precipitated on the surface of the CdS particles, to give CdS electrophotography having high sensitivity of long wavelength, capable of providing high-quality image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing cadmium sulfide for electrophotography, and particularly relates to a method for producing cadmium sulfide that can obtain high-quality images without reducing long wavelength sensitivity while reducing particle size. It is something.

One method that has been put into practical use for producing cadmium sulfide powder used in electrophotographic photoreceptors involves injecting hydrogen sulfide gas into a cadmium aqueous solution containing impurity sources such as copper to precipitate cadmium sulfide. After drying, a fluxing agent such as cadmium chloride is added to increase grain growth and improve crystallinity of the powder. In particular, if the amount of flux is more than 20% by weight relative to the cadmium sulfide powder and the firing temperature is 50°C or more higher than the melting point of the flux, the shape of the cadmium sulfide particles produced will be significantly different. It is simple and has high crystallinity, and an electrophotographic photoreceptor using it exhibits excellent characteristics.

The characteristics of a photosensitive plate used for electrophotography, particularly the sensitivity, are determined by the surface condition of the cadmium sulfide particles used in the photosensitive layer and the number of barriers between the particles.

In order to obtain high-quality images, it is generally advantageous to create a photosensitive layer using cadmium sulfide having a small particle size. However, reducing the particle size increases the barrier between particles in the photosensitive layer, which inevitably lowers the sensitivity. Furthermore, a slight change in particle size can cause a large change in sensitivity.

In addition, interest in intelligent copiers has increased recently, and demand for copiers that use laser light sources has increased. Photoreceptor particles having the following characteristics are required.

In conventional systems, when the particle size is reduced to improve image quality, the required sensitivity cannot be obtained in the long wavelength region. The present invention relates to a method for producing photoreceptor particles that can be used in copiers such as those described above, by improving long-wavelength sensitivity while reducing the particle size.

The present invention comprises the steps of producing cadmium sulfide particles having a small particle size and depositing a surface layer on the surface of the formed cadmium sulfide particles with a formulation having even longer wavelength sensitivity.

Shape like above? The electrophotographic properties of the cadmium sulfide particles are determined by the properties of the particle surface. Therefore, in the method of the present invention in which a further layer of cadmium sulfide is deposited on the particle surface, the properties of the particle before depositing the surface layer are Does not significantly affect the characteristics of Therefore, increasing the resistance of such particles can have the added benefit of increasing durability.

That is, the gist of the present invention is 4 to 10X per mole.
A mixed flux consisting of sodium chloride/cadmium chloride is added to cadmium sulfide containing IO-' moles of copper so that the cadmium chloride content is 5 to 15 moles, and the mixture is heated to 50°C from a temperature equal to the melting point of the flux. A method for producing cadmium sulfide for electrophotography, which is characterized by firing at a high temperature, then dispersing it in water, adding copper, indium, and a compound that generates sulfur when heated, and heating. be.

The specific method of the present invention is to add a specific flux to cadmium sulfide containing specific copper, mix until uniform, and heat the mixture at a temperature selected within the range of 50°C from a temperature equal to the melting point of the flux. Calcinate to collect single particles with small particle size.

After dispersing this fired product in water, appropriate amounts of copper, indium, and a substance that generates sulfur upon heating are added, followed by heating. By this operation, a further cadmium sulfide layer containing copper, indium, and chlorine is deposited on the surface of the cadmium sulfide particles. Initiating a reaction using a substance that generates sulfur when heated allows the precipitation reaction to occur slowly, so that a uniform layer can be deposited on the surface of small particles such as the cadmium sulfide used in the present invention. is necessary. 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 preferably a lithium/cadmium chloride mixed flux.

In the present invention, in order to utilize this flux for the next surface layer precipitation reaction, and to precipitate the surface layer in an amount of 5 to 15 molti relative to the raw material cadmium sulfide, a mixed flux is used. Select the composition and amount of addition. Furthermore, since the resistance of the deposited layer changes depending on the chlorine concentration in the flux, this is also taken into account when selecting the composition of the flux and the addition m'.

(5) During the precipitation reaction, the chlorine concentration should be 0.2 to 0.5 mol/!
The most effective case is For cleaning after firing, the ratio of 21 parts water to 100 grams of cadmium sulfide is optimal considering the cleaning efficiency, so the amount of chlorine in the solution is 0.
．． It becomes 4-1.0 mol.

The amount of cadmium chloride is 5 to 5 to the raw material cadmium sulfide.
The selection from the range of 15 moles is derived from the thickness of the surface layer to be deposited; if it is less than 5 moles, the surface layer is thin and susceptible to the influence of the layer below. On the other hand, if it exceeds 15 moles, it will affect the particle size of the particles that are finally formed.
The effect of small particle size is lost.

Based on the above results, FIG. 1 shows the preferred range of the sodium chloride/cadmium chloride mixing ratio and addition amount with diagonal lines.

As in the present invention, when the chlorine concentration must be increased in order to extend the sensitivity to long wavelengths, the cadmium concentration is also specified, so the mixing ratio of the fluxing agent can only be adjusted in the region where sodium chloride is high. Not satisfied. Additionally, in general, the more flux (6) added, the higher the firing temperature can be, and the more grain size will grow, the easier it will be to form single grains. When the amount added is small, the firing temperature must be lowered as much as possible to prevent grain size growth.

It is advantageous to add a large amount of copper in order to increase durability, but if it is too large, the surface layer will be affected. The amount of addition that is effective for durability and does not affect the surface layer is 5 to 10 liters per mole of cadmium sulfide.
The fired product is dispersed in water and then disassembled, then hooked,
Indium and a substance that generates all sulfur when heated? Then, water is further added to make the total amount Th2J, and then heated. 8
After reaching 0° C., heating is continued for 60 minutes, and then heating is stopped. Through this reaction, cadmium sulfide containing copper, indium, and chlorine is deposited on the surface of cadmium cisulfide.

Thereafter, washing is repeated by decantation until the conductivity of the supernatant reaches 20 μS/an. Furthermore, in order to remove all impurities remaining on the particle surface, the particles are stirred for 60 minutes in the presence of an ion exchange resin. After separating the resin, it is filtered and dried overnight at a temperature of 60°C. The finished powder is
After firing again, cleaning is performed in the same manner as after firing, and cadmium sulfide is completed.

The amounts of copper and indium to be added to the deposited layer should be determined in the range of 5 to 10 x IO' mol (per mole of cadmium sulfide produced), and 7 to 15 x 10' mol, taking into account the amounts of copper, indium, and chlorine. is preferred.

As substances that generate sulfur when heated, sodium thiosulfate, thiourea, etc. are excellent. Since the decomposition reaction to sulfur is not fast, it is preferable to add 8 degrees twice the amount actually required in order to completely react the remaining cadmium.

The cadmium sulfide particles created in the above manner have a small particle size, and the photoreceptor created using these particles has a large particle size, so it is possible to obtain high-quality images with good resolution, and also at long wavelengths. It is also possible to obtain the same degree of concealment in the area as with conventional particles with a large particle size.

Furthermore, since the copper concentration in the particles used as bulk is high, durability is also excellent.

This will be explained below using examples.

Example 1 Cadmium sulfide 1 containing 7X10' moles per 1 mole of 9 copper'
To 0.00 gr, 15.5 gr of cadmium chloride, 34.5 gr of sodium chloride, and 34.5 gr of sodium chloride were added, mixed well, and then filled with quartz melt 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, dismantling, copper and indium total 6.8 x 10 each
, 1.19 X 10 mol, sodium thiosulfate'
After adding 0.085 mol of i, water is added until the total amount is 21. This aqueous dispersion solution was heated with stirring and heated to 80
Once the temperature is reached, heating is continued for an additional 60 minutes. after that,
Repeat washing until the conductivity of the supernatant liquid is 20μS7cm or less, and then add 25m+ of cation exchange resin and anion exchange resin each! ! Add in portions and stir for 60 minutes. After leaving the resin for 9 minutes, it was filtered and dried at 60° C. overnight.

This cadmium sulfide was filled into a quartz mortar 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 solution became 1.0 μS/crn 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 coated on an aluminum substrate with a film thickness of 40μ using vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, manufactured by UCC) as a binder, and after drying, a polyester film with a thickness of 25μ was further applied on top. (Product name: Mylar, made by Diafoil) was applied as a sample for measurement.

Example 2 Cadmium chloride 17.9 gr, chloride (
10) Thorium 17. After adding Igrk and mixing well, the mixture was filled into a quartz crucible and fired at 430° C. for 60 minutes.

(The melting point of the mixed flux corresponds to 426°C in the case of this example.) After cooling, it is dispersed in water and disassembled, and copper and indium are each 5.9 x 10. After adding 9.8 x 10'' mol and further thiourea' (5, 0, 20 mol), water was added until the metal value reached 21. This solution was heated with stirring until it reached 80°C, and then Heating was continued for an additional 60 minutes.Then, the cadmium sulfide was washed and dried in the same manner as in Example 1.The cadmium sulfide all-silica crucible was filled and re-fired at 430°C for 60 minutes.Then, in the same manner as in Example 1, Washing and drying were performed using the same method, and a photosensitive plate was prepared using the same method.

Comparative Example A fired product fired in the same manner as in Example 1 was dispersed in water, disassembled, washed and dried in the same manner as in Example 1. This powder was filled into a quartz crucible, re-fired at 450°C for 60 minutes, washed and dried in the same manner as in Example 1, and processed into a photosensitive plate in the same manner. Sensitivity was measured for the prepared photosensitive plates of Example f11.2 and the comparison row 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.

In the measurement, the white metal shutter 2 of the halogen lamp 1 was irradiated with O for 2 seconds as a pre-exposure, and after being left for 0.2 seconds, a high pressure (Va)f was applied to the relay switch 5k for 0.2 seconds. After leaving it for 0.2 seconds (open), it was irradiated with light for a total of 0.2 seconds, and the voltage change (Vp) at that time was measured using the metal plate 7 and the surface electrometer 8, which were at the same voltage as the photosensitive plate.

Note that vp is the voltage applied to the photoconductive layer. The sensitivity is set in advance by voltage Vai so that Vp is 600V,
At the same time, the change in Vp was measured by changing the total irradiation exposure of 800 nmO light, and after determining the EV curve, the half-reduction exposure was obtained from this curve.

Furthermore, since the grain size is fine, the smoothness of the photosensitive plate produced is high, and the resulting images have improved resolution.

As for the durability, it was confirmed that the sensitivity was also improved while the durability was improved by showing the same level as the comparative example in which a large amount of copper was added.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between the ratio of mixed flux and the amount added.
The shaded area indicates the range that can be used in the present invention. FIG. 2 is a diagram showing a device 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.
...Sensitizer, No. 6 1U''′ Crystal insecticide combination ratio 4-(mole, ratio) Figure 2

Claims (1)

[Claims] A mixed flux consisting of sodium chloride/cadmium chloride is added to cadmium sulfide containing 4 to 1 mole of copper per mole so that the amount of cadmium chloride is 5 to 15 moles, and the flux is fused. 50 from the temperature equal to the point
After firing at a range of temperatures as high as ℃, dispersed in water, the copper,
A method for producing cadmium sulfide for electrophotography, which comprises adding indium and a compound that generates sulfur when heated, and heating to produce cadmium sulfide for electrophotography.