DE2513933C3 - Electrophotographic recording material - Google Patents

Description

The invention relates to an electrophotographic recording material comprising a layer support, a electrically conductive layer made of a metal, a glassy selenium containing 0.05 to 3 μm thick Sensitizing layer and a layer made up a Poty-N-vin.ylea.nbazoli-Miateitiakals, charge-retaining and i-transporting Layer..

It. is known, thin layers of, vitreous selenium on an electric! riding pad either directly desolate indirectly via an electrical barrier layer to apply undidiinni with a relatively thick Layer of a »polymeric carbazole derivative, such as Poly-vinyl acetate as a photosensitizing layer to cover (USrPSen 37 25 058,. 38 50 629, ZA-PS

ίο 7101! 2118 and Prepint of the Annual Conference, Society of Photographic Scientists and Engineers,] uni 1972..S. 1! 1 ^! 6-117).

Die.L ¹ S-PS. 37 25058 teaches the use of metallic aluminum as an electrically conductive layer.

This combination cuts the most serious Disadvantage; that the glassy selenium-containing layer on the metallic aluminum layer in the. Over time can be injured very easily if it is thinner than 3 μm, which leads to an impairment of the light sensitivity

sensitivity of the recording material leads; in addition, the adhesive strength between the vitreous selenium-containing layer and the metallic aluminum layer is relatively poor, so that the recording material can hardly or very difficultly be used as a stable, flexible recording medium. An aluminum foil rolled at 500 to 600 ^° C. develops an oxide layer on the surface. An applied in vacuum in a conventional aluminum foil layer of vitreous selenium μιη thickness of less than 3 goes from its initial reddish-brown color after \ to 2 months at 30 ⁰ C and a relative humidity above 70% partially in black over; Such a recording material with black selenium no longer has normal photosensitivity and a completely unusable adhesive strength between the aluminum and selenium layers. In the case of a vapor-deposited aluminum layer, a change in the vitreous selenium to a crystalline form is induced, so that overall it can be said that aluminum is a physical

see and / or chemical change of selenium in the adjacent selenium layer favored. Such modified Selenium layers lead to the formation of a background in the form of a veil or white dots that follow stand out clearly from the toner.

About the poor adhesive strength of a selenium layer, even a thickness less than 3 μm, to an aluminum layer to improve, attempts were made to roughen the aluminum layer mechanically or chemically; such Additional treatments are time-consuming, cost-increasing and require trained staff. The problem the adhesive strength is more evident with thin layers that are supposed to be flexible than with stiff layers thick aluminum plates such as those used in xerography.

Attempts have been made to use other conductive metals as electrodes for electrophotographic recording materials made from layers containing vitreous selenium . B. Use of copper, zinc, nickel. Iron, chromium, indium, tin, titanium. Silver Gold

ho and their alloys or inorganic semiconductors Materials like copper iodide and tin oxide. However, these materials show either too little Adhesion to the selenium layer, the chargeability is too low, the metals act as a catalyst

unwanted changes in the selenium layer and / or they react with increasing aging Selenium.

The invention was based on the object a

ilectrophotographic recording material! and : in process for the production of the same which the glassy selenium-containing layer hardly l be injured by the electrically conductive pushes can increase photosensitivity over long periods of time remains unaffected and the bond strength between the glassy selenium containing layer and the electrically conductive layer is improved so that the Recording material! shows increased flexibility. In addition, transparency was also sought. It were thus long storable according to the invention and extremely stable recording materials aimed at, the stability of which is retained even after repeated use.

The given task was en invention with the one designated according to the claim: electrophotographic Recording material! solved. The material uses a layer based on a polymeric carbazole derivative as the charge carrier layer, including the Polymer of an N-vinyl carbazole represented by the following formula

in which X has the meaning given, or a copolymer of this N-vinylcarbazole with another Vinyl compound such as vinyl acetate and methyl methacrylate is understood. Number and position of the substituents in the carbazole ring and the degree of polymerisation of the polymer depend on the manufacturing process and are not restricted to the configurations described here. The thickness of the selenium layer is as in US-PS 37 25 058 between 0.05 and 3 μΐη.

The electrophotographic recording material of the present invention can be prepared by the following method are produced: A substrate is coated in a vacuum with a thin layer of metallic palladium in a thickness of 5 to 1000 Å, applies a thin layer to the palladium layer in a vacuum vitreous selenium in a thickness of 0.05 to 3 μm and coated with a relatively thick layer of charge transporting polyvinyl carbazole a conventional coating method.

The invention provides an electrophotographic recording material which has a excellent shelf life even under the adverse physical and chemical effects mentioned above Influences. It "can be repeated in a copier that works on the principle of image transfer works, use. Because the adhesive strength between the palladium layer and the selenium layer is excellent is, the recording material is to be produced as a tape and offers larger in this embodiment Freedom and opportunities for constructive training of copier machines. Since it is translucent in Can make shape, it is for electrophotographic imaging systems of reflex type or mil back exposure can be used.

The palladium layer of the recording material is advantageously 5 to 1000 Å and preferably 10 to 100 Å thick. With these strengths one achieves a higher stability of the adjacent, vitreous selenium containing Layer.

For the recording material according to the invention, layer supports are preferably made of one

Polyethylene terephthalate, polyethylene naphthalate,
Polycarbonate, polyimide, polyamide,
Imide-amide copolymer, cellulose acetate,
Polystyrene, polypropylene, polyethylene,
Polyvinyl chloride,

Acrylnitrii-butadiene-styrene copolymer,
Acrylonitrile-styrene copolymer, polyacetal,
Epoxy resin, polyurethane or one
iQ thermosetting polyester

used. The use of these supports makes it possible to obtain improved flexibility of the recording material.
In the drawings is the

Fig. 1 is a sectional view of a two-layer photoreceptor in accordance with the present invention, showing

F i g. 2,3,4,5 and 10 show changes in the oil surface potential in the dark (V ₀ ) and in the residual potential after exposure (V _r ) of the photoreceptors from the examples of the specification after they have been repeatedly charged in the dark and discharged by exposure

F i g. 6,7,8 and 9 show the electrophotographic Properties (i.e., charging in the dark, potential drop in the dark, and potential drop in exposure) of the Patterns of the photoreceptor according to the present invention used in the examples of the following description Invention.

In Fig. In Fig. 1, the reference numeral 5 denotes an embodiment of a two-layer photoreceptor array according to the present invention. The substrate denoted by the reference numeral 1 can be omitted an electrically conductive or insulating material. Suitable for use as substrate 1 Conductive materials are, for example, various metals as well as alloys and chemical compounds the same. Suitable electrically insulating materials are, for example, glass, ceramics and Plastics.

The present invention can also be carried out when the substrate 1 is metallic Uses aluminum.

A thin layer of metallic palladium is applied from a palladium vapor, which is bonded to the Reference numeral 2 is designated. This layer 2 can, if the substrate 1 is conductive, electrically conductive or be isolating. If the substrate 1 is conductive, the layer 2 should also be conductive.

A thin layer of vitreous selenium denoted by the reference number 3 serves as a photogenerator and injects iicro-excited charge carriers (mainly Holes) in an adjacent cover layer 4. The layer 3 can be applied to the layer 2 by vapor deposition produce.

The top layer is an organic polyvinyl arbazole layer which is essentially insensitive to light in the visible range, but which ^; n the selenium layer can transport charged carriers with a negative charge to the surface.

Fs has been found in accordance with the present invention that with a very thin layer evaporated palladium than directly under the vitreous selenium layer, the stability of the latter fts can improve significantly. In particular, it improves the storage life and the service life of the selenium layer in the glassy shape. It has also been shown that the adhesion between the palladium layer and the

Selenium layer is extremely strong and the finished photoreccptor can be used in a copier on the image transfer principle in which the photoreceptor as a repeatedly detachable belt, because of its flexibility, the photoreceptor can be in the form of a Web material, d. H. can be produced industrially on a large scale at low cost.

From the results of the experiments according to the present invention it can be seen that Preferably used materials for the substrate 1 are insulating materials in glass form - for example Glass and polymer organic plastics. With regard to the universal applicability of the The two-layer photoreceptors of the present invention are those used for the substrate 1 Materials preferably flexible and translucent. Commercially available plastic films such as those made of polyethylene terephthalate, Polyethylene naphthalate, polycarbonate, polyimide, polyamide, polyamideimide, cellulose acetate, Polystyrene, polypropylene, polyethylene, polyvinyl chloride, polyacetal, epoxy resin, urethane resin and thermosetting Polyester resins can preferably be used. Foils made of biaxial are best suited oriented and crystal-rich polyethylene terephthalate or naphthalate (hereinafter referred to simply as PET or PEN) or films made of polyimide or its copolymers, as these polymer films have high tensile strength, heat resistance and transparency. With regard to the electrophotographic Properties, the substrate is preferably electrically conductive. However, if the substrate 1 is an electrically insulating material, this can easily be made electrically conductive by adding a layer Palladium evaporated according to the present invention, the surface resistance of the evaporated xs Palladium layer should be less than IC ohms per unit area. For the production of the layer 2 conventional vacuum processes such as conventional evaporation in a vacuum using Electron beams, HF induction, or clektrisehen Resistance as a heat source, sputtering with direct or high-frequency alternating current as Leislungsqucllc and use ion implantation with equal success.

The melting and boiling points of metallic palladium are very high; h> ^Γ > () or 245O "C at atmospheric pressure. If the layer 2 is made of palladium by conventional vapor deposition in a vacuum, the pressure in the vacuum vessel should be less than 10-mm Hg and the palladium should be briefly heated As is necessary to generate the required palladium dump. In this process, the substrate 1 can preferably be pre-cleaned - for example by ion protection - before coating with palladium, in order to improve the ventilation between the substrate 1 and the layer 2.

The most effective method for producing the layer 2 is a Aufstllubungsverfahron in which the coating takes place under a pressure of 5 χ " ¹ to 10- ^J mm Hg in argon or nitrogen gas. In this case, the substrate I does not need to be pre-treated.

The palladium slide produced in this way makes them Adjacent layer 3 of glassy selenium inert '' 5 against physical and chemical changes and adheres firmly not only to the substrate I, but also to it the overlying layer 1 of glassy selenium.

Metallic palladium itself is inert to atmospheric air even in a thin layer and can be therefore expose to the ambient air for long periods of time. There is also one on top of the thin palladium layer 2 applied layer 3 made of vitreous selenium, as already stated, is also stable and can therefore also Long-term exposure to the ambient air without careful treatment. This fact is for them Large-scale manufacture of the two-layer photoreceptor is of considerable advantage.

The reason why the thin vapor-deposited palladium layer makes the glassy selenium layer inert, is not yet known. However, one can assume that the palladium layer acts as an inhibitor (or more negative Catalyst) acts for the vitreous selenium, which in itself has a tendency to change its appearance. the suitable thickness of the layer 2 is between 5 and 1000 Å, preferably between 10 and 100 Å greater than 1000 A, the inhibiting effect of the layer decreases 2 for the instability of layer 3, presumably due to the change in structure and surface activity.

If the layer thickness is more than 1000 Å, layer 2 continues to peel off due to cracks in layer 2 Substrate t.

As already stated, the preferred thickness used is in the range of 10 ... 100 Å, where the Surface resistance has been found to be 10 ... 10 * ohms per unit area. In this area the resulting two-layer photoreceptor exhibits excellent photographic properties regardless of whether the substrate 1 used is electrically conductive or insulating.

A typical example of a material such as is preferably used for the substrate 1 is a flexible PET film with a transmittance of approximately 90% or more for white light. After coating with the layer 2 in a thickness of 5 ... 1000 Å, the transmittance of the substrate 1 with the layer 2 is between 50 and 80% for white light. The finished flexible two-layer photoreceptor with such a transparent PHT film produces an excellent electrostatic image when exposed imagewise from above or from below.

The identification of such a thin layer of pulludium can be done by fluorescence X-ray analysis. If a quantitative analysis is required, one leads preferably carry out a Rudioaktivierungsunalyse.

The following describes the production of layer 1 in the glassy selenium. The layer 1 according to the present invention can be produced by known techniques - for example by conventional vapor deposition. For this purpose, reference is made, for example, to US Pat. Nos. 27 39 079, 27 53 278, 29 62 376, 29 70 906 and 37 25 05t.

Gs is Ulis of technology also known that a Sehich made of glassy selenium for electrophotographic photos receptors see modify lulls to the photosensitivity jichkcit overall as well as the spectral limpfindliehkei to improve in the range of visible radiation, and by adding at least one effective doping * by means of which one adds either homogeneously or with a density filling in the vertical direction of the layer

Effective doping agents are, for example, iron, tellurium, cadmium, sulfur, antimony and sulphide. This modification is applied to layer 3 according to the present invention for the same purpose as according to the hour of technology, examples. layer 1 tellurium and arsenic can be approximated to ^r > ... 4

Add wt .-% homogeneously or with a concentration gradient in the coating direction.

In any case, the type, amount to be added and the concentration gradient of the dopants are varied are determined by the properties desired in the resulting photoreceptor and are not limited limited to those expressly mentioned here.

In order to produce a layer 3 modified with the aforementioned doping material, two are known Process suitable, d. H. alloy vapor deposition and mixed vapor deposition (“co-evaporation”). in the In the former case, an alloyed material composed of selenium and at least one dopant is evaporated in a vacuum and applied to layer 2. In the latter case, each of the materials (e.g. '5 Selenium and tellurium) each in a heating vessel of the evaporation system and heats them up together, whereby the supply of heat is controlled so that the composition of the gas mixture of the constituents remains constant.

Regardless of whether the layer 3 is a doping ^ o Contains agent, it knows such a firm adhesion to the layer 2 that it is only in the tape peel test difficult to remove from layer 2.

Finally, a layer 4, the polyvinyl carbazole, is applied according to a conventional method and optionally contains additives such as binders, plasticizers and active ingredients. The finished one The two-layer photoreceptor according to the present invention exhibits excellent photrophotographic properties Properties, d. H. a high capacity to accept charges, a low potential drop in the dark and a normal drop in potential under irradiation with visible light. This electrophotographic Properties are almost the same as those of a fresh two-layer photoreceptor with one Aluminum foil as layer 2.

Example I.

Of the following samples, Sample G was made by the method of the present invention. (<> While the other are comparative samples. All samples were made with the construction of I "ig. I, with the exception of Sample U. That for the substrate The material used 1 was a polyethylene decrepluhalite film throughout with the exception of sample II. The 4s layer 3 consisted of a simple glassy sol 0.3 µm thick throughout. The transparent organic layer 4 of poly-N-vinylcarbazole cut into all samples Thickness of 18 μην Table I shows the materials used in this way for the individual samples for layer 2 and their thickness.

Table I.

Sample material of the Klektroilcnxehichi

thickness

A. soft aluminum foil 12 µm B. whore aluminum foil 12 [in C. vapor-deposited copper layers 200 Λ D. Copper iodide about 500Ä Ii stacked in a vacuum 1500 Λ aluminum 1· stacked in a vacuum
Miiiüxl 500 λ Cj IN ICKCI
stacked in a vacuum 30 Λ palladium Il Stainless chair slide 50 um

(.0 The electrode layers listed in Table 1 were obtained using the following methods:

The electrodes of samples A and B were produced by gluing the aluminum foil onto the PET foil substrate, the electrode of sample C by vapor deposition of the copper onto the surface of the PET foil. For this purpose, copper dividers were used. introduced a purity of 99.99% in a korbförmigcn tungsten coil heater under a vacuum of 1 χ 10 ~ ⁵ mm Hg, the heating element of 0.8 mm tungsten wire was.

The electrode of sample D was produced by iodizing the copper-metallized PET film by immersion in a solution of 10% by weight or 90% by weight of carbon tetrachloride. The copper layer of sample D was produced according to the procedure given for sample C, but to a thickness of 100 Å. After the copper layer had been iodized, the iodized film was dried. In this way, a transparent and electrically conductive PET film coated with copper iodide was produced, the transmittance of which for incandescent light was 90%.

The electrodes for samples E, F and G were produced by sputtering metallic aluminum, nickel or palladium onto the surface of the PET film. The sputtering was carried out by the direct current cathode method under the following conditions: The anode consisted of a chrome-plated copper substrate, the cathode was a sheet of the above-mentioned material. The distance between anode and cathode was consistently 3 cm and the internal pressure during the sputtering was kept at about 2 × 10 -4 mmHg argon gas. A DC voltage of 5 kV was applied across the electrodes. The PET film was brought into close contact with the surface of the anode sheet and the respective cathode metal was dusted onto the film surface, a thin metal layer being formed there.

In the case of Sample H, the stainless steel foil was used as both the substrate and the electrode used.

The layer of glassy selenium was formed with evaporation of granules of metallic selenium a purity of 99.99% in a tungsten basket heater made of 0.5 mm tungsten wire under a pressure of I χ 10 * mm Hg applied. The thickness of the so applied The layer of glassy selenium was 0.3 μm. For the selenium layer, a solution of the in Table 2 listed ingredients applied and dried. The thickness of the dry layer was in each case 18 μm.

Table 2

Ik'NUimltell weight parts

Poly-N'-vinylcurbnzene too Polyeurbonate 30th Orthotophenyl 40 Dlplienylmethuri-cliisocyantii 3 Monochlorobenzene 900 Dichlorathnn 300

lcde of the samples was ilunn with the following tos evaluated:

1 Ί.

Tesi 1

Test 2

Tesi 3

D. Fi g.2-D I. ig. 3-D F. ig.4-D E. Fi g.2-F. I. ig 3-F. F. ig. 4-Π F. Fi G. 2-F r "fig. 3-F F. ig. 4-F Ci Fi G. 2-c; I. i g. J- (I F. i g. 4-Ci H Fi β. 2-11 I. ig. 3-11 F. ig. 4-11

Test 4

10

Test I.

In order to estimate the useful life of each sample, each sample was continuously charged 10000 times in the dark in an ambient temperature of 18 ... 22 ° C and a relative humidity of 40 ... 60% and discharged again by sufficient exposure. In this test, the voltage applied to the corona discharger was -6 kV DC. The surface potential in the dark, V ₀ , and the residual voltage V _{r were} measured alternately in every second charging cycle. In each cycle the exposure of the sample was 200 Ix for 1 sec. The cycles were repeated at a frequency of 30 per minute.

Test 2

Under otherwise the conditions of test 1, the samples were tested at a constant ambient temperature of 50 ⁰ C.

Test 3

After storage of the samples for 1 month at 50 ^° C. and 30% rel. Test 1 was repeated on them.

The results of tests 1, 2 and 3 are shown in FIGS. 2, 3 and 4, as summarized in Table 3 below.

Table 3 Table 4

Sample results

A After the 8 to 10 thousandth copy, the

original color of the glassy selenium layer turns black. The corresponding Copies showed underground veils.

B The original color of the glassy selenium

layer had turned too black after four to six thousand copies. The corresponding Copies showed underground veils.

C Unusable as there is no charge.

D The surface potential Vo decreased and the

optical density of the toner image became low.

E After 2000 ... 2500 copies, the original

The light color of the glassy selenium layer changes to black. The corresponding Copied images had a veil in the background.

F The surface potential Vo decreased and the

optical density of the toner image became low.

G Between the first and the 20,000th copy

no change in image quality was found.

H After more than 5000 copy cycles, the

glassy selenium layer black. The picture background veiled.

Fig. 2-A Fig. 3-A Fig. 4-A

Fig. 2-B Fig. 3-B Fig. 4-B

As a result of the reaction between selenium and copper, the selenium layer was colored black. The resulting two-layer photoreceptor sample settled in Do not charge in the dark.

Test 5

The adhesive strength between the layers of the samples was evaluated. For this purpose, a pressure-sensitive Tape 25.4mm wide used. First, the tape was applied to the Surface of the sample is applied and then by hand in the tape direction (180 "turn) along the Sample area torn off.

Test b

Sample results

To evaluate the practical life of each sample, the sample was placed in a copier for normal paper clamped and the quality of the $ 0 table S developed image and copyrights Sample determined the cycle of the copying process to which the sample was subjected in the copier consisted of following steps: A.

1. Negative charging in the dark with a corona charger;

2. Image-idle exposure through a lie: B

3. Toning with toner application by magnetic brush; C.

4. Transferring the image-wise toner application to ordinary paper through negative corona discharge 60 D dung; and E.

3. Clean the surface of the sample with a Rotary head brush.

The temperature was maintained 4O ⁰ C during testing in the F copying machine consistently at 35 ... and used as a template a standard test image of the electrophotographic · G graphic Society of Japan. Table 4 shows the results of this test.

The same peel test as in Test 5 was performed with a

Sample of 50 χ 50 mm carried out immediately

in distilled water for 24 hours beforehand

l.s room temperature has been kept submerged

Tests 5 and b gave almost the same results are therefore summarized in Table 5.

Layer separation occurred between de

Aluminum foil and the delicious Selcnschich

on

Good

Separation occurred /. Between the Kupiei

foil and the glassy selenium layer uuf

Good

Layer separation occurred between de

Aluminum layer and the glossy side

layer up

Layer separation with / wipe the nod

layer and the delicious selenium layer

Good

Layer separation occurs between the stool film and the glassy selenium layer ttuf

From the results of Tests i to 6, it is easy to see that Sample G, which was produced according to the present Invention was prepared, the other samples has excellent properties over other samples.

Example 2

A PET film with a thickness of 100 μm was used as the substrate. Each sheet was cut into pieces of 50 × 50 mm, and the pieces were then applied to the surface of a cathode sheet which was cooled from behind with water. A palladium sheet with a purity of 99.99%, the size of which was 60 × 60 mm and a thickness of 3 mm, was used as the counter electrode; the electrodes were 30 mm apart. A high-frequency alternating voltage of 4 kV at a frequency of 13.56 MHz was applied to the electrodes and the pressure was kept at 3 × 10 ² mm Hg in argon gas. Under these conditions, the palladium sputtered onto the foil surface for four seconds. Thereafter, there was a uniform, thin layer of palladium on the film.

The layer thickness of the palladium on the foil was determined to be 35 Å by two methods, namely by the conventional optical method and by radioactivation analysis ^{, in which the density of the palladium layer was 12.16 g / cm 3.} The transmittance for monochrome light with a wavelength of 550 nm was 60%, the surface resistance about 2 χ IO ² ohms per unit area. The palladium layer applied in this way did not separate from the film in test 5.

The vitreous selenium layer was then evaporated onto the surface of the palladium-coated film under a reduced pressure of I 10 ⁵ Hg. The temperature of the evaporation vessel was held at 38O ⁰ C. In this way, a vitreous selenium layer with a thickness of about 0.4 μm was created. This selenium layer did not separate from the film in test 5.

Was then applied, the organic composition of Table 2 on the surface of the selenium layer for 3 hours in a hot-air-pressure furnace, which was maintained at 5O ⁰ C, dried; thereafter the organic cover layer had a thickness of 15.5 μm. This two-layer photoreceptor is referred to as "Sample I" in the following.

Sample 1 was tested at a surface temperature of consistently 55 "C in accordance with test 3 of example t and thereby exposed to the test cycle more than 30,000 times uninterruptedly. FIG. 5-1 shows the results of this endurance test. As can easily be seen, others the initial values c of Vo and V _r scarcely even after 30,000 duty cycles.

Meanwhile, the electrophotographic properties of the sample I were observed; H. the Dark cargo, the Potentiulobfall in the dark and under Exposure conditions were as follows:

Dynamic measurement methods Corona discharge »·

voltage - 6 kV

Light source tungsten filament

Incandescent lamp

ambient temperature 2854 ⁰ K illuminance

the sample surface 9.5 Ix

Exposure per second 3 Ix see

It was found that the original electrophotographic properties of sample 1 had remained the same even after the test cycle had been repeated 30,000 times.

For comparison with sample 1, a sample) was produced under the same conditions as sample I _1, but with the following exceptions:

As the substrate, a PET film has also been used of 100 μηι thickness, the surface of which, however, previously lake in a vacuum of 10 ~ I χ ² mm Hg for 30 had been bombarded with ions. Then became

ίο on the treated aluminum foil surface A purity of 99.99% is evaporated in a vacuum and an aluminum layer with a thickness of 500 Å is formed. The peel test (test 5) showed that the aluminum layer adhered firmly to the substrate. the However, adhesion between the aluminum layer and the vitreous selenium layer was insufficient; at the Test 5 of Example 1 separated about two thirds of the selenium layer. However, the aluminum layer remained Adhere undamaged to the substrate.

Other fresh samples of Samples I and] were used as photoreceptor elements in a copying machine. Here, the sample sheet was wound up on a rotating drum of 20 cm diameter, the Sheet on the drum was in the dark using a corona discharger with a two-wire corotoron with applied -7 kV negatively charged and then exposed. The exposure unit consisted of two stationary fluorescent lamps of 20 W and a moving master stage. By moving both the drum as well as the template platform, a slide-like image was placed one after the other on the sheet and then using the latent image by the conventional cascade method a barrier layer of glass beads, then the developed image is attached to a single-wire corotoron - 7 kV were placed, transferred to simple writing paper and the image on the paper with heat an infrared heater / device fixed. Finally it was the used sheet is cleaned and refreshed with a rotary filling brush. The copier was working at a speed of 12 copies per minute.

Samples I and) of the same size were tested simultaneously with this copier by running them in parallel to each other uuf the rotary drum were clamped.

. (is the surface potential given to samples I and] in the dark - 750 ... 800 V or 900 ... 950 V at normal room temperature Value kept constant during the test A test image standardized by the Elcktrophotographic Society Oil Japan served as a template.

In the case of sample I, dei could be found between the image first and that of the ten thousandth copy keir determine essential difference. As one thin toner coating that was deposited after each Wiped 5000 cycles with a soft cloth, there was also a significant difference in image quality between the first and the twenty thousandth Kopii hardly notice.

In the case of Sample J, it became about one hundred its copy on the. Paper a light tench noticeable. After about the thousandth copy, the image contrast had decreased noticeably and was de Underground eggs have become dense; the quality of the image could therefore no longer be regarded as sufficient will. The selenium layer of the sample had formed in various places raised, but only in small ones

Split areas. This shift was obvious the result of the mechanical friction that occurs during development and cleaning of the copier This surface parts with a lifted layer resulted in white spots on the image copies.

Furthermore, a part of the area in which black selenium was clearly visible to the naked eye caused a slightly toned background at the corresponding point on the copy paper, where the paper had to be white because of the white color of the original, ι ο with regard to the black part of the area, the occurred after 4,000 copies, a test for charge in the dark, charge decrease in the dark and charge decrease on exposure was then carried out, the result of which is shown by curve 104 of Fig. 6]. Compared to curve 103 (initial properties), curve 104 shows a reduced chargeability, a sharp drop in the dark potential and a high residual potential.

In addition, Sample J was subjected to the test of Test 1 with the surface temperature being kept at 55 ° C. As the F i g. 5-J shows, the surface potential V ₀ dropped very quickly in the dark. In contrast, the residual potential V _{r increased} with sufficient light. The difference between samples I and] could easily be seen from a comparison of the corresponding properties in FIGS. 5-1 and 5-].

After a fresh sample] for three months in a room with a relative humidity of 40 ... 60% had been held, white tree-like crystals appeared in some places; they had each other evidently formed by modification from the glassy selenium. By touching the white area with The selenium layer, which had become white, could easily be touched by the finger together with the organic cover layer solve locally.

B e i s ρ i e 1 3

A polyimide film with a thickness of 100 μm was used as the substrate here.

The film had the standard size of 25.7 × 31.4 cm. First, the surface of the sheet at 10- ² mmHg was treated with an electrical alternating field of 60 Hz, then the vacuum is increased to 6 χ 10 ~ ⁶ mm Hg, and palladium vapor-deposited in a purity of 99.99%. For this purpose, the palladium was heated in a tungsten basket heater made of tungsten wire with a diameter of 0.8 mm.

The transmittance of the palladium-coated film for incandescent lamp light was 30 ... 35%. And the surface resistance of the palladium layer 10 ... 10 ² ohms / unit area, that is, enough for an electrode for an electrophotographic photoreceptor.

The palladium layer did not separate from the tape peel test with the above-mentioned adhesive tape Substrate.

Vitreous selenium was then μίτι in a thickness of 0.3 according to the same method as in Example 2 vapor-deposited, coated with the one given in Table 6 solution and dried in a Warmdruckluftofc-n at 40 'C ¹ on the palladium layer. The thickness of the organic cover layer was then 12 μm. The finished two-layer photoreceptor produced in this way is referred to below as "sample K".

45

6c

Table 6

component

Parts by weight

Poly-N-vinyl carbazole

Monochlorobenzene

Dichloroethane

100 900 300

For comparison, a photoreceptor using hard rolled aluminum as a substrate and also as an electrode was used manufactured. The surface of the aluminum foil was bombarded with ions before the selenium coating, then a layer of glassy selenium to 0.3 μm thickness applied using the same procedure as for sample K. This glassy selenium layer adhered firmly the aluminum foil and left in the peel test as described above. not peel off. Without ion bombardment the glassy selenium layer could of course easily be removed from the aluminum foil.

Furthermore, the solution of Table 6 was applied as in the procedure used for Sample K. and dried; this top layer had a thickness of 12μΐη. The finished one, produced in this way The photoreceptor is referred to as Sample L hereinafter.

Immediately after the completion of samples K and L, these were subjected to the test for dark charge, potential drop in the dark and potential drop on exposure and then to investigate the aging effect for 200 days at 45 ° C and 90% rel. Keep moisture. The properties of sample K are shown in FIG. 7-K, in which the curves 105 and 106 represent these before and after aging, respectively. It can be seen from this illustration that the sample K almost completely retains its initial properties even under high temperature and ambient humidity.

Curves 107, 108 of FIG . 7-L show the same properties for sample L before and after aging. In the case of the aged sample L, the chargeability is lower, and almost no difference can be found between the potential drop in the dark and that upon exposure. Thus, a characteristic essential to an electrophotographic photoreceptor was lost. A considerable area of the selenium layer of sample L was slightly blackish in color. In contrast, in the case of sample K, no visible change was found.

55 Bet game 4

Under the conditions of Example 2, the palladium and di selenium layers and then the solution in the table were applied to the surface of a PET film and dried. In this way a complete two-layer photoreceptor cntstani nac ^! of the present invention. The thickness of the dry top layer was 12 μm. This sample is referred to below as “sample M”. For comparison, a sample N was produced by the same procedure as the sample J, except that the material of Table 7 was used for the top layer.

abelle 7

lcslandiei! Weight toüe 3-chromed poly-N-vinyl : arbazol (bromination: IOOMol% 100 Polycarbonate 20th Diphenylmethane diisocyanate 3 Monochlorobenzene 900 Dichloroethane 300

After completion of the samples M and N, they were tested for their properties (ie dark charge, potential drop in the dark and on exposure). Thereafter, they were rel in an atmosphere having a temperature of 5O ⁰ C at 90%. Brought moisture, the sample M held there for 50 hours, the sample N for 5 hours and, after this aging, the electrophotographic properties were tested. Figures 8-M and 8-N show the properties of Sample M and N, respectively; curves 109, 111 represent the properties before aging, curves 110, 112 after aging. As can be seen, the properties of sample M - with the prlladium layer under the photosensitive vitreous selenium layer - are more stable than those of sample N without the palladium layer .

Example 5

A PET film with a thickness of 100 μm was used as the substrate used on which a palladium layer was sputtered under the following conditions:

the atmosphere

pressure

Tension between

Anode and cathode

Distance between anode

and cathode

anode

cathode

filled with argon gas
chamber

2 χ iodinine ed

5 kV DC voltage

3 cm

chrome-plated copper sheet
Palladium sheet

The foil was kept in close contact with the copper sheet. Another PET film was made metallized with aluminum in the conventional way in a vacuum.

These two metal-coated foils were cut to the standard size 25.0 × 36.4 cm and then stretched onto the sample holder in a vacuum chamber with two independent heating vessels in the form of molybdenum boats. The distance between the boats was 1 cm. A piece of metallic selenium with a purity of 99.99% was placed in one of the boats, and metallic tellurium powder with a purity of 99.99% in the other; After evacuating the chamber to 10- ⁵ mm Hg, the two boats were gradually heated simultaneously. First, reddish-brown selenium vapor was deposited on the surface of the palladium- and aluminum-coated foil, then the mixed steam of selenium and tellurium. The layer condensed from the two vapors on both films was dark red in color.

After the Klcbcbandtest already explained, the adhesion between the Se-Tc-Lcgicrungsschicht and the palladium-coated foil on the one hand and the ammonium-coated foil on the other.

The adhesion of the alloy layer to the palladium-coated foil was strong; the layers left do not separate from each other. In contrast, there was the adhesion of the alloy layer and the aluminum-coated layer Foil so weak that they separated easily when tested.

Then the solution explained in Table 6 was applied to the Se-Te alloy layer and 5 hours. dried for a long time at 40 ° C in a hot air oven.

ίο Of the two finished samples, the one with the Palladium schichl as an example according to the present invention in the following as "sample P", others with the Aluminum layer called "sample Q" as a comparison sample.

As one of the main ingredients is poly-N-vinylcarbazole If the layer containing the layer shrinks on drying, it will pucker due to the internal stresses in the layer on. In the case of Sample Qi, the Se-Te alloy layer dissolved together with the top layer after 10 hours.

spontaneously from the aluminum layer - obviously due to the influence of these internal stresses in the Top layer. In contrast, sample P showed no such layer separation. A separation of the Layers occurred even after the sample had been stored for three months at 40 ° C. and 90% relative humidity. Moisture does not rise.

The F i g. 9 shows the electrophotographic properties of sample P, curve 113 showing the initial properties and curve 114 showing the initial properties of sample K for the comparison of the light sensitivity. Sample P was subjected to the endurance test from Test 1; Fig. 10 shows the results. As can be seen from FIG. 10, almost no change in V ₀ and V _r occurs in the sample P up to the 100,000th cycle.

Example 6

On two sheets of PET film with a thickness of 100 μm two types of electrodes applied: eii.c was applied with a 50 μιτι thick aluminum foil laminated, the other vaporized with aluminum, the latter to a thickness of 0.2 μια Both sheets were then by the method of Example 5 together with a 30 Å thick palladium layer and a 0.3 μm thick glassy selenium layer Mistake. Furthermore, the two sheets were coated with the solution explained in Table 2 and dried; the dry thickness of the two outer layers was 18 μm.

The two samples of two-layer photoreceptors thus obtained became the above Tests 1, 2 and 3 described above. For both arcs the results were almost the same as for the one Sample G. In Test 4, the two samples were subjected to a practical multiple copy test. Out This endurance test of the two samples showed that they had a service life of 15,000 to 20,000 copies. After this Copy number, the samples gradually turned black; the copied images produced showed a foggy one Underground.

However, these samples gave excellent results in comparison to Prober without palladium under the selenium layer * Results.

From the above observations it can be concluded that the presence of a thin palladium layer is a very effective means of preventing crystals from forming in glassy selenium. Tuesday Adhesion between the individual layers was found to be good, and Test 6 showed both samples no separation of layers.

The effect of the presence confirm a palladium layer samples rel at 4O ⁰ C and 95% were. Moisture had been retained, examined microscopically and by X-ray analysis. In the sample without a palladium layer, the vitreous selenium layer became black after one or two days and white tree-like microcrystals, which appeared to be spherulites, were observed in the black area of crystallized selenium. In contrast, a sample with a thin palladium layer did not show any crystal formation for longer than 10 days. These results are extremely valuable for practical application.

Example 7

15th

A 100 μm thick PET film was coated with palladium layers in seven different thicknesses, d. H. 1, 5, 10, 30, 80, 1000 and 2000 Å provided by the sputtering method of Example 2, the thickness being through Changing the dusting time has been set. A was also applied to the palladium-coated surface vitreous selenium layer evaporated to 0.4 μm, as it is in the Example 2 is described.

The seven types of the PET film coated with selenium and palladium were placed in an oven at 40 ^° C. and 95% rel. Moisture is retained to keep up with the changes in the selenium layer as it progresses

£ 3Κ

Ü, after an Al. ™ «

Days

kernels

.wipe the PaUadiunv »nd

Samples prove the adhesive strength

³¹ The ^S p ^e ; ^C o ^h b ^e e ⁿ with the 1 A thick Pai.adiumschicht could not be used since as electrophotographic electrode their Oherflächenwiderstand was 10 "Ohm unit area. From the standpoint of electrical LeUfänigke a two-layer Photorezepto for electrophotography ifeße prepared MAssign one 7e PET - Foil replaced by aluminum foil. E.g. a palladium layer only 1 Å thick could hardly surprise you with the crystal strength of the vitreous selenium layer.

In addition 9 sheets of drawings

Claims (4)

Claims; 1. Electrophotographic recording material from a layer carrier; one electric conductive layer made of a metal; a 0.05 to 3 μm thick layer containing vitreous selenium and a layer of, a material with units! the formula -CH-CH ₂ - where X is a hydrogen or halogen atom, a nitro, alkyl, aryl, alkaryl, amino or alkylamino group, characterized in that that it contains a layer of palladium as a metal layer. 2. Recording material according to claim 1, characterized in that it is a 5 to 1000 Å, preferably 10 to 100 Å, thick layer of palladium contains 3. Recording material according to claim t, characterized in that it is a layer support from a Polyethylene terephthalate,
Polyäthylennapliithalat, Polycarbonat,
Polyimide, polyamide,
Imide-amide copolymer,
Cellulose acetate, polystyrene, polypropylene,
Polyethylene, polyvinyl chloride,
Acrylonitrile-butadiene-Siyrene copolymer,
Acrylonitrile-styrene copolymer,
Polyacetal, epoxy resin, polyurethane or
a thermosetting polyester
contains 4. Method of making an electrophotographic Recording material in which an electrically conductive layer is applied to a layer support vapor-deposited or sputtered from a metal, a layer containing selenium and then a layer of a material with units of the formula -CH-CH ₂ where X is a hydrogen or halogen atom, a nitro, alkyl, aryl, alkaryl, amino or alkylamino group is applied, characterized in that the metal is palladium is used.