JPS5849619A - Preparation of photoconductive cadmium sulfide - Google Patents

Abstract

PURPOSE:To obtain photoconductive cadmium sulfide particle having smooth surface, by reducing and precipitating Cd<2+> in solution to the surface of Cd particle having rough surface thereby smoothing the surface, and calcining the particle in sulfur atmosphere. CONSTITUTION:Cd<2+> ions are chemically reduced in a solution and precipitated to the surface of a Cd particle having a number of protrusions and indents to make the surface smooth, and the particle is calcined in an atmosphere containing 0.05-0.5% sulfur based on the CdS. The CdS particle has preferably a diameter of >=1mu to prevent the agglomeration in water. The reducing agent is, e.g. sodium hypophosphite, dimethylaminoborane, hydrazine, etc. When the amount of sulfur in the atmosphere for the calcination of precipitated Cd is too high, the electrical resistance of the calcined CdS becomes extremely high to cause undesirable effect to the electrophotographic characteristics of the CdS, especially the quality of the image, and accordingly, the amount is to be selected within the range between 0.05 and 0.5% based on the weight of CdS.

Description

[Detailed description of the invention] The present invention relates to a method for producing photoconductive cadmium sulfide.

There are two main methods for producing cadmium sulfide pigments: wet and dry.Industrially, CdSO is mainly used.
4. A wet method has been implemented in which an aqueous solution of CdC42 or the like is reacted with hydrogen sulfide gas. For electrophotography, the produced CdS powder is further fired with a flux and an activator, or the activator is co-precipitated with CdS in advance during the reaction and then fired to activate the CdS powder before use. By the way, CdS particles obtained by the wet method (1) like this depend on the precipitation conditions, but
Generally, when observed with an electron microscope, etc., the surface is extremely uneven, and in some cases, there are many protrusions. When mixed in this state, the powder has strong cohesive properties, making it difficult to handle, and when dispersed in resin, it exhibits strong thixotropy, making it difficult to coat onto conductive substrates. . Furthermore, in terms of electrophotographic characteristics, when there are many irregularities, there is generally a tendency for the deterioration of the light attenuation characteristics of the photoreceptor due to the previous history to increase, and the specific surface area increases, resulting in a decrease in environmental dependence, especially humidity characteristics. This may cause problems such as deterioration.

Therefore, in the present invention, with the aim of manufacturing CdS particles without such unevenness, the uneven surface of CdS particles is chemically reduced and precipitated in a total solution of CD ions by a so-called chemical plating method. After smoothing the unevenness of Cd
In a sulfur atmosphere of 0.05 to 0.5 h for S, 40
Firing at 0°C to 600°C, the final surface is pure Cd.
This method is characterized by obtaining S powder.

9 A There are no restrictions on the particle shape of the CdS powder to be subjected to this treatment, but it is preferable that it not aggregate in an aqueous solution, so it is preferably a particle size of 1 μm or more.

Reducing agents used include sodium hypophosphite, dimethylaminoborane (DMAB), hydranone, etc. The amount of Cd precipitated varies depending on the reaction conditions and type of reducing agent, but it is sufficient to smooth out surface irregularities. is sufficient, and it is better to avoid precipitation of n or more. When firing in a sulfur atmosphere after Cd precipitation, if the amount of sulfur is too large, carbon
dS powder has a very high resistance and has a negative effect on electrophotographic properties, especially image quality, so 0.05% of the CdS weight is
% to 0.5%.

Specific examples are shown below.

Example I Cu and Ct activated number average particle size 3.0-4.0
Cd5100g' with μ was washed with water and deionized in advance, and the entire surface was thoroughly washed, and then dried at 70°C for 24 hours.
After that, 0 CdC1210 was chemically plated under the following conditions. i' NaH2PO2・H2O24g H201000rnl Above CdS powder 100g CHCOONa'3H20' 10g Bath temperature
80℃pH5,4 10 minutes each (Document-1), 30 minutes (Document-2), 6
After stirring for 0 minutes (Document-3), wash.

It was deionized and dried at 70°C for 24 hours. Thereafter, 0.2% by weight was added to the CdS powder after the whole body yolk powder plating, and after thorough mixing, it was filled into a quartz tube with a slotted lid and fired at 450° C. for 60 minutes. After cooling to room temperature, washing with water and deionization was performed until the conductivity of the washing liquid became 1.0 μV/- or less, and drying was performed at 70° C. for 24 hours. After drying, observation with an electron microscope revealed that CdS
It was observed that all the particles were rounded and had a slightly smooth surface.

Figure 1(a) shows the iPI of this example, and Figure 1(b) shows the document-2.
A micrograph (3500x) after treatment is shown.

Komu et al.'s CdS i vinyl chloride co-vinyl acetate copolymer resin (trade name: VMCf (manufactured by VCC) was used as a binder and coated on an aluminum substrate in a film thickness of 40 μm, and after drying, a polyester film with a thickness of 25 μm was further applied on top. (Product name: Mylar: manufactured by Diafoil) was applied to the entire surface and used as a sample for measurement as described below.

Example 2 After chemical plating was performed by stirring for 30 minutes in a bath with the same composition as in Example 1, 1it0.01% of the sulfur added (material-
4), 0.05% (Document-5), 0.1% (Document-6)
, 0.5% (Data-7), and 1.0% (Data-8), and baked in four different ways as in Example 1 below, and formed into a photosensitive plate, which was used as a sample for measurement as described below.

J7*91+Li l The CdSi used in Examples 1 and 2 was directly filled into a Rugge, and after baking at 450°C for 60 minutes, it was made into a photosensitive plate under the same conditions as in the Examples, and used as a material for Comparative Example 5.

For each of the 8 buildings listed above, Document-1 to Document-8, 2
The following conditions were exposed for 24 hr under 5℃, humidity 40%, light irradiation and 25℃, humidity 40%, in the dark and 25℃, 100% humidity, light irradiation. All measurements were performed and all effects were compared. The measurement was carried out using the apparatus shown in FIG.

That is, the glass plate 3 having the transparent electrode 4t 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 through a relay integer 5.

Measuring beam race itte 5 High voltage (
Va) ffi was applied, the film was left for 02 seconds (in an oven), and then light was irradiated for 0.2 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 entire photosensitive plate. Note that Vp is the voltage applied to the photoconductive layer.

Further, as a pre-exposure, measurement was carried out using a metal plate 7 and a surface electrometer 8 at the same voltage as the white light (Vp) full photosensitive plate of Helogung 27g 1. Note that vp is the voltage applied to the photoconductive layer.

・Furthermore, as a pre-exposure ~ ・Irradiate for 0.2 seconds with the white metal shutter 2 of Rogunlang 1, leave it for 0.2 aea, apply Va, Q, leave it for 2 seconds, and then change the original again for 0.2 seconds.
sec irradiation, and the voltage change Vp' at that time was measured.

Measure the Vp and vp' when Va is set to 2000V, and the Vp value when Vai is set to 2000V.
By determining the speed of optical attenuation when applying Knee 2000 ■, V
The humidity characteristics were completely evaluated from the ratio of Vp when a=-2000V and Vp when Va=-2000V of the sample stored under a 100% humidity environment.

The entire lees pot is shown below.

The difference in Vp-yp/ is smaller in the example than in the comparative example,
The light fading indicates that the speed of the fly is fast. Also, when comparing the difference in Vp -yp/ between samples left in the light and samples left in the dark, the difference in Vp -yp/ in the example is slightly smaller, and even if the storage conditions are different, there is almost no difference in the contrast of the images formed. This shows that the formation stability is excellent. Furthermore,
Vp of a sample left in the light and Vp of a sample left in a monkey environment with 100% humidity
Comparing p'fc, it can be seen that the example shows less deterioration due to humidity and less environmental dependence.

[Brief explanation of drawings]

Figure 1 (t,) (b) shows the raw material CdS in Example 1.
and micrograph of Material-2 after treatment (X3500), M
FIG. 2 is a diagram showing an apparatus it 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 Fig. 1 (a) X, 5500 (b) -2.・′be, ,・,”, ′・

Claims (1)

[Claims] CdS particles, which have many irregularities on the surface, are chemically reduced and precipitated in a cd''+ ion gold solution to make the surface smooth, and then treated with a sulfur atmosphere of 0.05% to 0.5% relative to CdS. A method for producing photoconductive cadmium sulfide, which comprises firing in a medium.