JPS5911899B2 - electrophotographic recording material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to an electrophotographic process in which selenium, a selenium alloy or a selenium compound is deposited as a photoconductor on an electrically conductive layer support, the photoconductor containing phosphorus as a further component. Concerning recording materials.

Electrophotographic recording materials are used in electrophotographic copying, which is widely used in copying technology.

These methods are based on the property that photoconductive materials change electrical resistance when exposed to activating radiation. After charging and exposure to activating light, a charged latent image is created on the photoconductive layer that corresponds to the optical image. 10 In the exposed areas the conductivity of the photoconductive layer increases so that charge can flow away (at least in part, but in any case more strongly than in the unexposed areas) through the conductive support, while Charge is largely retained in areas that are not exposed to light.
The charge can be made visible on the image powder 15, a so-called door, and if necessary, the door image can finally be transferred to paper or other substrate. Organic and inorganic substances are also used as effective substances in electrophotography.

For this purpose, selenium, selenium alloys, and selenium compounds are important. The mechanical, optical, electrical, and thermal properties of electrophotographically useful materials place different demands on their effective and advantageous practical use, and conventional layers cannot meet these demands. It is often the case that only 25 people can be satisfied at the same time.

However, it is known that some properties of materials useful for electrophotography can be significantly influenced and improved, for example, by the addition of elements from groups I, II, or II of the periodic system of elements. . 30 For example, the low thermal stability of layers consisting of amorphous selenium, which generally has a tendency to transition to an undesired crystalline state, can be improved by the addition of main group elements such as phosphorus, arsenic or antimony.

Similarly, the low hardness of the amorphous selenium layer is improved by the addition of these elements. Among the elements of the first main group listed here, arsenic is particularly well known and is either homogeneously distributed at various concentrations and uniformly throughout the thickness of the layer, or distributed over specific concentration profiles and variations. Frequently used for individual layer ranges in proportions.

Phosphorus, on the other hand, has hitherto been of no importance for this purpose. This is because mixtures and compounds of phosphorus and selenium are hygroscopic and unstable in a wide range of phosphorus concentrations from less than 0.1% to more than 50% in selenium (Gmelin, Phosphorus Volume, C. Department, 1965, p. 607). Especially the percentage of phosphorus is 0.1, 0.3, 1, 3, 10%
Experiments on a number of samples of selenium also pointed out and demonstrated that this system is sensitive to humidity. Therefore, such a system cannot be put to practical use in electrophotography. On the other hand, the system consisting of selenium and phosphorus is
It has properties that make it highly desirable for use in some application areas. In other words, by adding phosphorus to selenium, it is possible not only to practically completely suppress the crystallization of selenium and obtain a highly hard layer at the same time, as in the case of adding arsenic to selenium, but also to (Moreover, unlike and compared to the case of adding arsenic), the dark resistance can be significantly increased. This property can be used to advantage in any practical application; on the contrary, if the exposure time is long or the equipment is operated slowly, as is the case for example in most small equipment, the charge can be dissipated very rapidly. are avoided as undesirable. Similarly, if a mixture with selenium is to be deposited to form a deposited layer, and if it is necessary that the mixture partner of selenium be present in the resulting deposited layer in a concentration that is as constant as possible, arsenic can be added to phosphorus. It seems preferable to replace it with In other words, since the vapor pressures of selenium and arsenic are different, especially when the content of arsenic is low, at the beginning of such vapor deposition,
A layer consisting of almost pure selenium is obtained in which the arsenic content increases only gradually, and only towards the end of the deposition a steep concentration gradient of arsenic is obtained. To prevent this and to obtain a constant concentration throughout the layer thickness, expensive measures such as complicated temperature control during deposition or deposition from multiple evaporation sources are required. On the other hand, evaporating a mixture of phosphorus and selenium results in a phosphorus concentration that is more or less constant throughout the layer thickness. Finally, by adding phosphorus to the selenium, the spectral sensitivity of the photoconductive material can be controlled in a controlled manner and adapted to the respective spectral range of the exposed body.

The object of the present invention is therefore to provide a material which is made of selenium, a selenium alloy or a selenium compound and which contains phosphorus as a further constituent, but which is chemically stable and resistant and which also guarantees long-term practical use. Our objective is to provide electrophotographic recording materials.

Selenium, a selenium alloy or a selenium compound is deposited as a photoconductor on an electrically conductive layer support, the photoconductor containing phosphorus as a further component.

In electrophotographic recording materials, this object is achieved according to the invention in that the photoconductor additionally contains arsenic. Surprisingly, in contrast to the above-mentioned system of selenium and phosphorus, in which a reddish film is observed after a short period of time as a sign of decomposition, the photoconductor constructed according to the present invention , exhibits no phenomena such as hygroscopicity and subsequent chemical decomposition, is stable and resistant, remains unchanged even after boiling in distilled water for 1 hour, and contains virtually no phosphorus or selenium as dissolved components. It turned out that it was not detected.

The invention therefore provides a photoconductor which is distinguished by a high stability against decomposition, in which the crystallization of selenium is completely suppressed, so that the amorphous state is avoided. Permanently maintained, the photoconductor has a high hardness that increases further with increasing phosphorus content.

The mixed system P2se3-As2se3 has special advantages. Compared to pure selenium, its optimum sensitivity is increased, and its glass transformation temperature is likewise increased compared to pure selenium, so that higher operating temperatures are possible. On the other hand, the glass transformation temperature, which has a value lower than that of arsenic selenide (AS2Se3), allows a simpler production of photoconductors made of arsenic selenide. Finally, the significantly higher dark resistance of this photoconductor than that of a photoconductor made of As2se3 is due to the fact that this photoconductor can also be used in cases where the often used arsenic selenide cannot be used due to its rapid discharge, i.e. for example also in small devices. It allows the body to be used as a recording material. In contrast to deposited layers of systems consisting of selenium and small amounts of arsenic, which exhibit a steep concentration gradient of arsenic towards the end of the deposition, unless prevented by special addition measures, such additions are Even without measures, the distribution of at least the effective sum of the proportions of phosphorus and arsenic, and thus also their relative distribution, becomes more uniform.

Finally, in practical use it seems particularly advantageous to: This means that the dark resistance of the recording material according to the invention and its spectral sensitivity can be made particularly precise for the respective intended use due to the large latitude in the concentration range of phosphorus and arsenic and the various additional possibilities of incorporating other additives. without compromising the aforementioned advantageous properties of high hardness, preservation of the amorphous state and prevention of hygroscopicity. This wide latitude of application is once again illustrated by FIG. 1, which shows the selenium-arsenic-phosphorus system in trilinear coordinates.

Such a composition, which consists only of selenium and phosphorus and corresponds to point 1 on the Se-P bond line in the coordinate system, has the above-mentioned undesirable property of being easily affected by humidity, but The range is excellent in its moisture resistance and hardness. Depending on the considered intended use of the electrophotographic layer and the necessary properties resulting from it, it is now easily possible using a trilinear coordinate network to set ranges corresponding to these requirements and then to select the compositions belonging thereto. become. For example, region 2 near the apex of the upper triangle, which has a relatively small content of phosphorus, also shows a small content of arsenic, the proportion of which is necessary to stabilize the phosphorus proportion.

Even within this range, if no significant change in electrophotographic properties is observed compared to pure selenium, in addition to an increase in hardness and resistance in the amorphous state, a slight increase in glass transformation temperature is observed. An increase in the transformation temperature has a practical advantage when using photographic recording materials. However, this range is especially excellent in the following points.

This means that the phosphorus can be evaporated from the source without concentration gradients in the layer being deposited, which greatly simplifies the deposition process as long as a layer is provided with a uniform concentration over the entire layer thickness. Become. Range 3 where the percentage of phosphorus and/or arsenic is significantly high and varies between 30% and 50%
In this case, a higher hardness of the recording material and a higher resistance to its amorphous state are observed. Depending on whether the proportion of phosphorus or arsenic is high, the photoconductive layer exhibits different sensitivities, with the higher the proportion of phosphorus, the lower the sensitivity.
At a high proportion of arsenic, corresponding to almost pure selenium, but close to the composition As2se3, the sensitivity reaches its highest value.

In the same way, as shown in the diagrams in Figures 2 and 3, if the proportion of arsenic is simultaneously lowered and the proportion of phosphorus is increased,
The dark voltage drop becomes smaller and the photoconductive edge moves towards shorter wavelengths.

The properties of systems whose compositions lie between ranges 2 and 3 exhibit properties that lie approximately between the aforementioned properties of the corresponding photoconductive layers.

The selection of the proportions of the individual partner substances therefore makes it possible to adapt them considerably to the particular conditions. For example, selenium in the range 49 to 99 atom %, phosphorus in the range 0.5 to 50 atom %, and arsenic in the range 0.5 to 50 atom % are selected. In particular, the mixed system X・(P2Se
3)-(1X).(As2Se3), where the value of X can be chosen, for example, between O and 0.8. The dark voltage drop and movement of the photoconductive edge in these systems are secondary to
As shown in FIGS. Other examples of layer compositions tested and their manufacturing conditions are shown below.

Example 1 0.1P2Se3+0.9AS2Se3 Sample weight 457, layer temperature 195℃, sample port temperature 3
70℃, evaporation time 40 minutes, layer thickness approximately 60μ Example 20.2P2
Se3+0.8AS2Se3 Sample weight 45y1 layer temperature 195℃, sample port temperature 3
55°C, deposition time 50 minutes, layer thickness approximately 55μ Example 30.4p2
se3+0.6As2se3 Sample weight 451, layer temperature 170℃, sample port temperature 3
45℃, deposition time 50 minutes, layer thickness approximately 55μ Example 40.6P2
Se3+0.4AS2Se3 Sample weight 457, layer temperature 160℃, sample port temperature 3
30°C, deposition time 55 minutes, layer thickness approximately 55μ Example 50.8P2
Se3+0.2AS2Se3 Sample weight 457, layer temperature 155℃, sample port temperature 3
20 DEG C., evaporation time 60 minutes, layer thickness approximately 40 .mu.. Another advantage of the photographic recording material according to the invention is provided by the possibility of incorporating further additives.

For example, it is advantageous to add one or more halogens, especially chlorine or iodine, to the recording material in a concentration range of 1 to 10,000 ppm, preferably 10 to 100 ppm. In this case, it may be advantageous to use the halogen in the form of its compounds. For the production of layer 0 of the recording material, conventional vapor deposition methods have been found to be suitable.

For example, evaporation from a single evaporation source is possible, and in mixed systems with the composition PtSe, -As2se3, this method is at the same time economical and results in a homogeneous elemental distribution. However, in some cases evaporation can also be carried out from several sources, with a selenium-phosphorus system in one evaporation vessel and a selenium-arsenic system in the other evaporation vessel. This method is recommended especially when arsenic concentrations are very small. The present invention has the features described in the above-mentioned claims, and examples of its embodiments are as follows. (1) Photoconductor is 49
An electrophotographic recording material according to the claims, which contains selenium in an amount of 99 at.%.

(2) The electrophotographic recording material according to claim 1 or (1), wherein the photoconductor contains 0.5 to 50 atom % of phosphorus.

(3) The electrophotographic recording material according to claims (1) and (2), wherein the photoconductor contains 0.5 to 50 atomic percent arsenic.

(4) The photoconductor is a mixed system X・(P,Se,}-(1-X
)・(As2Se3), (1
) to (3).

(5) Mixed system X・(P2Se3)-(1-X)・(As
2Se3), the value of X is between O and 0.8,
An electrophotographic recording material according to claims (1) to (4).

(6) Claims (1) through (5) wherein the photoconductor additionally contains one or more halogens.
) Electrophotographic recording materials described in .

(7) The electrophotographic recording material according to any one of claims (1) to (6), wherein the photoconductor contains chlorine and/or iodine.

(8) the photoconductor additionally contains one or more halogens at a concentration of 1 to 10,000 ppm;
An electrophotographic recording material according to claims (1) to (7).

(9) An electrophotographic recording material according to claims (1) to (g), wherein the photoconductor additionally contains one or more halogens at a concentration of 10 to 100 ppm.

Electrophotographic recording material according to claims (1) to (9), in which AI...logen is used in the form of its compounds.

[Brief explanation of the drawing]

Figure 1 is a three-line coordinate diagram of the selenium-arsenic-phosphorus system, Figure 2 is a diagram showing the relationship between the mixing ratio of recording material components and dark voltage drop, and Figure 3 is a diagram showing the mixing ratio of recording material components. FIG.

Claims (1)

[Claims] 1 In recording materials in which selenium, selenium alloys or selenium compounds are deposited as photoconductor on an electrically conductive layer support and in which the photoconductor contains phosphorus as a further constituent, the photoconductor additionally contains arsenic. An electrophotographic recording material comprising: