JPS5831342A - Manufacture of photoconductive cadmium sulfide particles - Google Patents

Abstract

PURPOSE:To obtain cadmium sulfide particles suitable for electrophotography, high in crystallinity, uniform in particle shape, and high in sensitivity, by mixing a flux with cadmium sulfide, baking the mixture at high temp., and again baking it in presence of chloride. CONSTITUTION:A flux, such as CdCl2, ZnCl2, or NaCl, is added to CdS by >=20wt% of it, and the mixture is baked at a temp. higher than the m.p. of the flux by >=50 deg.C. A chloride, such as CdCl2 or NH4Cl is mixed with the burned cadmium sulfide in 5X10<-4>-5X10<-3>mol/mol of CdS, and the mixture is again baked at 400-500 deg.C, thus permitting intended photosensitive cadmium sulfide particles to be obtained. Since these particles are doped with chlorine acting as a donor, they have high sensitivity, and when a photosensitive plate is formed using these particles, and used for a high speed copying machine, or the like, an image having high electrostatic contrast and good quality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing cadsium sulfide particles for electrophotography, and particularly to a method for producing cadsium sulfide particles that are highly crystalline and uniform.
This relates to a method for producing sulfiding power P (rim) which is a residue particle and has high sensitivity.

The most common method for producing tD is photosensitive electrophotographic photosensitive materials, which are typically used in electrophotographic photosensitive materials. The sulfur salt is reacted with hydrogen sulfide to precipitate rtium sulfide particles, which are then fired at a high temperature to dope the cadmium sulfide particles with an activator.

That is, the photoconductive sulfidation force P is added to the cadmium sulfide particles with CuCj2 e Cu804 etc. as an activator and CdC1 as a fluxing agent.

It is generally produced by mixing Cu, Cj, etc. into cadmium sulfide by mixing a halide of Z*CLx@ and firing it. However, in such conventional methods, 9C is produced through the firing process.
In company d8, a large number of defects are observed near the surface of ca8o during precipitate formation.

Since this front page defect becomes a photocarrier unit, it increases the optical memory of CaS, that is, slows down the optical response speed, and makes it possible to increase the speed of photoreceptors made using such CaA. If applied to a copier, initial copying will be $P#If! Electrostatic contrast between bright and dark areas becomes insufficient.

The particle shape of 90d8 produced by the method described above is composed of secondary particles that are formed by aggregation of particles together and form a strong aggregate. Particles vary in size (3-dimensionally aggregated to form a group, islands, or 2-dimensionally aggregated to form a flat plate), but some of them are large, ranging from about 10 microns to several tens of microns. Some are as small as microns.

A photoreceptor made using Cd8 containing a large number of such coarse particles has a poor surface condition, and as a result, the resulting image TFI is severely rough and the resolution is insufficient. (9) In the case of a photoreceptor further provided with an insulating layer, the insulating layer may seep into the Cd8 layer, making it difficult to obtain a photoreceptor with good handling properties.

The above drawbacks were solved by adding a large amount of flux, firing at a temperature higher than the melting point of the flux, and then re-firing the pages.

However, the photoreceptor fabricated using the sulfurized square particles obtained by the above invention exhibits good electrophotographic properties in almost all respects;
It had the disadvantage of being slow at L. For this reason, when applying to high-speed copying machines or copying machines that reduce power consumption for the purpose of energy saving,
The sensitivity is low, resulting in images with 0 sharpness.The present invention aims to improve these drawbacks, and basically improves the sensitivity by doping chlorine, which is a donor, into cadmium sulfide particles. The aim is to improve

The present inventors have discovered that by firing the chlorine removed during firing together with a chlorine compound during re-calcination, it is possible to dope the donor and increase the sensitivity.

The amount of chloride added does not need to be so large that it can be used as a flux, and is 5×10 to 5×1 G-smol@/
About 1 ol is sufficient. Since the amount is at this level, the chloride has the advantage that it does not act as a flux and does not cause particle growth.

In addition, if ct is present, the amount of Ct remaining in cadmium sulfide will be 1) K more than 5 x 10" mole/mole.
Disadvantages appear, such as rounding, which requires controlling the amount of Ct to have an appropriate resistance, and an additional manufacturing step.

On the other hand, the amount of Ct is 5 × 10 mol@/n5ol*
It cannot contribute to sensitization in the following cases.

Although it is possible to add the chloride directly as a powder and mix it with the sulfurized chloride, it is better to dissolve the water-soluble chloride in water from the perspective of uniformly adding it to the sulfurized chloride. After that, a wet method in which the water is evaporated after adding it to the sulfurized cadmium powder to create a sulfurized cadmium chiller and evaporating the water after uniformly mixing it will give better results.

Added chloride, cact, ZmCL2, KCl1
NH4CL@ is preferred, especially CdCA2, NH4Cl
is more suitable since no impurity cations remain after re-firing.

The fluxing agent used in the present invention is a IIK commonly used fluxing agent that diffuses the active agent into the CAB.

ZmCL, , KCL, NaC2, NH2Cl
, Cd804, etc., or a mixture of several types in an appropriate ratio.

A preferred example of a mixture of CdCA2 and an alkali metal chloride is a mixture of CdCA2 and an alkali metal chloride. Typical alkali metal chlorides are ZmCL and KCl. The content of alkali metal chloride in the entire flux is preferably 90 mol or less and 10 mol or more.

In the present invention 1111, the amount of flux is preferably 20 or more, particularly preferably 30 to 50%. If it is less than 20, the produced Cd8 particles will be sintered and become coarse particles, and the surface shape Cd8 is also non-uniform, has insufficient potential retention, and has poor resolution. In addition, if the firing is carried out at a temperature that is 50°C higher than the melting point of the flux, the Cdli particles produced are large in diameter, resulting in poor resolution and poor coating properties. However, the electrostatic contrast of the initially formed image becomes low.

In addition, in the manufacturing method of the present invention, the firing temperature is 600°C.
The following are preferred. In addition, from the viewpoint of yield, it is preferable to add 65 g or less to the fluxing agent OCAB K.

Further, in order to control the durability and image quality when used as a photoreceptor, steel is usually co-precipitated during precipitation or added during re-firing and fired. The addition amount is suitably at most 10-8 mol of Ix per 14 mol of sulfiding power P, particularly preferably from 5 x lθ mol to 5 x 10-'% mol. As the copper compound added to Cd8, copper chloride, sulfide, sulfide, etc. are used, and chloride steel and sulfuric steel are particularly preferable. It may be mixed,
If the copper compound is aquatic, make it into an aqueous solution and add CdH.
Both wet methods, in which the water is evaporated after addition to water, give good results, but the wet method is better in terms of uniformity. !
The firing is preferably carried out at a temperature of 500° C. or lower, particularly 400 to 500° C. If the firing temperature is 500° C. or higher, residual charges in the photoreceptor become susceptible to IA.

Cadmium sulfide produced according to the present invention has high crystallinity, and when observed using a scanning electron microscope, it is found to be a single particle with no agglomeration of particles, and its surface is smooth. In addition, a photoconductive layer is created by dispersing it in electrophotographic resin/4-ingu and coating it on a support, and if necessary, an insulating layer is applied thereon to create a photosensitive plate. It has been found that high electrostatic contrast can be obtained from initial copies by application to high speed copying machines. In addition, since the cadmium sulfide powder obtained according to the present invention has a uniform particle shape and a uniform particle size, the coated surface of the photoconductive layer created is smooth and has a very smooth surface. The image obtained is as follows. Moreover, in the method according to the present invention,
It can be seen that the sensitivity is faster than when no chlorine remains.

Examples will be described below.

Example 1 Cda raw powder 100I with no added impurities produced by precipitation
act! Add 30% of tzo II and NaCA, mix well, fill in a quartz crucible, and heat at 530°C for 30 minutes.
(In addition, from the melting point line and phase diagram of the mixed flux of CdCA2 h NaCt, cacz, @ 2NaCA (
According to a 10,000x O electron microscope photograph, the particle 11 surface is very smooth and has a hexagonal shape. It was observed that each particle had a shape peculiar to the crystal form, and each particle was a single particle of 2 to SsO bucket.

Next, according to the caBKfi method, chlorinated steel was added in a molar ratio of 4 x 10-' and cadmium chloride was added in a molar ratio of 10-s, mixed well, and then reconstituted at 450°C for 1 hour. After re-baking, it was washed with water, residual ions were removed using an ion exchange resin, and dried. After dispersing this Cd8 in an El chloride/vinyl acetate copolymer, it was applied to a thickness of 40μ on an Alkiera 5 substrate, dried, and then a 15μ thick 717 ester film was attached to the photosensitive plate. When a photoreceptor with a layered structure was obtained, the surface was extremely smooth. When this photosensitive plate was subjected to a high-speed electrophotographic process of primary charging, then photoexposure, AC static elimination, and then full exposure, a substantial image with sufficient electrostatic contrast and sufficient sensitivity was obtained. As for my power, I was able to obtain 6 or more sharp images. Furthermore, this photosensitive plate was heated to 13s℃, s*s
Copy II again after being left in high temperature for 24 hours
29 results (contrast of dark areas)
There was no decrease in O2 or sensitivity (4IIToc), and an image with zero opacity was obtained.

Example 2 A mixed flux of CdCj, 301 and KCl 20 F was mixed into Cd8 CdB raw powder 1001 to which Cu was not added, and after thorough mixing, it was fired at 480° C. for 30 minutes. ,
Next, the thus obtained 90dS K wet method was used to add p-chloride steel at a molar ratio of 4 x 10'' and cadmium chloride at a molar ratio of 5 x 10'-s, and re-fired in the same manner as in Example 1. When the obtained 90d8 was made into a photoreceptor and evaluated, the same true hitting results as in Example 1 were obtained.
From the phase diagram, the melting point of the mixed flux of z2 and KCA is KCdC
The melting point of A is reduced to 390°C.

Example 3 Addition of precipitated impurities to 100 # of Cd8 raw flour
uCl2 to Cd8 K by wet method, molar ratio I
After adding 10"", add 41g of K CdCA, Na
9. Add 91% of CL, mix well, fill in a quartz crucible, and bake at 500°C for 30 minutes.9.

Next, 5 x 10''-' ammonium chloride was added to the cadmium sulfide thus obtained, and then re-sintered in the same manner as in Example 1.
The hexagonal degree of -8 is 100-.According to the electron micrograph, the particle surface is very smooth and has a unique hexagonal shape, and each particle is a uniform unit with a diameter of 3 to 5μ. It was observed that it was a single particle.

When the obtained 90 dai was made into a photoreceptor and evaluated, the same excellent results as in Example 1 were obtained.

Comparative Example Except for not adding chloride during re-firing,
After obtaining cadmium sulfide particles in the same manner as in Example 3,
A photoreceptor was prepared in a similar manner.

The sensitivity was measured for the above examples and comparative examples.
It can be seen that the speed is clearly faster than that of the comparative example9.

Next, measure the sensitivity of the photoreceptor using the measuring device shown in the drawing.

That is, a glass plate 3 having a transparent electrode 4 is pressed against the insulating layer surface of a photoreceptor 9, and the transparent electrode 4 is connected to a high-voltage DC power source 6 via a wire and a wire.

As a pre-exposure to the measurement line, a white light beam of 2mm f1 is emitted through the shutter 2 for 2 seconds**, and after leaving it for 0.2m, close the relay switch 5 for 0.2 seconds and apply a high voltage. (V, ) was applied to the photoconductive layer so that the voltage Vp was 600V, and after leaving it for 0.2 seconds (in an oven), it was irradiated with light for 0.2 seconds, and the voltage change ffp ) at that time was compared to the photoreceptor. Measurements were made using the metal plate 7 and the electrometer 8 on both sides at the same voltage.

Sensitivity was determined by irradiating light at the same time as voltage was applied and measuring the change in Vp by changing the exposure amount. After obtaining the E-7 curve, the half-reduction exposure amount was obtained from this curve.

As shown in the table below, the half-decrease exposure amount is faster.

[Brief explanation of the drawing]

The drawing shows an apparatus for measuring the sensitivity of a photoreceptor.

Claims (1)

[Claims] Mix 20 weight or more of a flux with the sulfurized cadmium,
In a method for producing a photoconductive sulfide frame which involves firing at a temperature 50°C higher than the melting point of the flux and then re-firing, 4111 involves re-firing in the coexistence of chloride. A method for producing erected particles.