EP0000582A2 - Electrophotographic recording material - Google Patents

Abstract

Electrophotographic recording material composed of an electrically conductive layer support, optionally an insulating intermediate layer and a photoconductive layer comprising at least one layer which generates charge carriers and transports charges, binders and customary additives, in which the recording material, when the layer support is relatively thick, is flexible in terms of adhesion and is repeated over rolls of at least 12 mm in diameter without hairline cracks. The recording material contains cellulose nitrate with a viscosity of 400 ± 25 cPoises at concentrations between about 4 and 12 percent in 5% aqueous acetone according to DIN 53 179 (standard type 4 - 12).

Description

The invention relates to electrophotographic recording material comprising an electrically conductive layer support, optionally an insulating intermediate layer and a photoconductive layer comprising at least one charge carrier-generating and charge-transporting layer, binder and conventional additive-containing layer, in particular a recording material with charge carrier-generating layer and charge transport layer. Multi-layer photoconductive layers are e.g. B. from German Offenlegungsschriften 21 08 935, 21 08 938, 21 08 944, 21 08 958, 21 08 968, 21 08 984 and 21 08 992 known. With relatively good electrophotographic properties, however, the mechanical properties are disadvantageous in that the polyvinylcarbazole used and mainly described in the form of a charge transport layer is not very flexible and, because of its large molecular weight and its chemical nature, is only slightly compatible or miscible with binders and resins. In addition, the adhesion of such multilayers to the electrically conductive substrate is insufficient for practical purposes. The use of these materials is therefore limited to photoconductor arrangements that are not mechanically resilient.

The German laid-open publications 22 20 408, .23 14 051 and 23 53 639 describe well-adhering and also flexible photoconductive layers. However, these are also sufficient when used in mechanically stressed, self-supporting recording materials such as, for. B. photoconductor tapes are not yet highest sayings. When the recording material is repeatedly guided over a narrow roller diameter, fine hairline cracks occur on the surface of the photoconductor. This strong bending stress on the photoconductor layer, which can also be on a relatively thick support, causes a gradual mechanical destruction of the photoconductive layer.

The described photoconductive layers also have a higher residual charge if conventional binders such as e.g. readily soluble polyester resins or copolymers of vinyl chloride / vinyl acetate etc. are present.

It was therefore an object of the present invention to provide an electrophotographic recording material which, with very good photosensitivity, has been modified and improved in its flexibility to such an extent that it can be safely used even on relatively thick substrates, for example as a continuous photoconductor belt, under great mechanical stress and for example, can be performed on rollers with a small diameter. It was also an object of the invention to provide a recording material with improved discharge properties, for example in the case of flash exposure.

This object is achieved by an electrophotographic recording material composed of an electrically conductive layer support, optionally an insulating intermediate layer and a photoconductive layer comprising at least one charge carrier which generates and charges Transporting compounds, binders and conventional additives layer and is characterized in that the recording material worked with a 75 to 250 _/ um thick layer support as a photoconductor tape is so flexible that it repeatedly leads over rolls of at least 12 mm in diameter, not to hairline cracks tends and that it contains a cellulocenitrate as a thickener, which has a viscosity of 400 ± 25 cPoises at concentrations between about 4 and 12 percent in 5% aqueous acetone according to DIN 53 179 (standard type 4 - 12), preferably between about 4 and 9 percent (Standard types 4 - 9).

This ensures that electrophotographic recording material can be made available which, compared to materials with the previously known and customary binders, has significantly improved photosensitivity and an extraordinarily low residual charge, both with continuous exposure and particularly with flash exposure, with great flexibility.

These properties permit the use of the materials according to the invention for mechanically highly resilient photoconductor tapes which run in a relatively fast cyclic copying process, particularly with flash exposure. Repeated guiding over rollers takes place in the bending stress test and is usually done 5000 times.

The arrangement of a simple photoconductive layer has the advantage of being simpler to produce itself (Fig. 1). The arrangement in separate charge carrier generating layer and charge transport layer, on the other hand, has the advantage of the compact arrangement of the particles and the optimal charge carrier generation rate (FIGS. 2-4). Less thermally stable dyes, which, for example, cannot be vapor-deposited onto the electrically conductive layer support, can be used in accordance with the arrangements in FIGS. 1 and 4.

In the development of photoconductive layers, the explicit use of cellulose nitrates in the various photoconductor compositions has hitherto not become known. Cellulose esters and ethers are often mentioned in general descriptions of photoconductor layers, for example when enumerating binding agents (DE-AS 12 46 407). The exceptional special position in terms of flexibility and photo; sensitivity properties is completely surprising.

It is known from German Offenlegungsschriften 24 52 622 and 24 52 623 to use cellulose nitrates in protective layers over photoconductor layers, as are known, for example, from DE-AS 15 72 347, in addition to other binders. On one hand, these protective layers can have added conductivity-increasing substances in a resistance range of the layer between 10 ⁷ - 10 ⁹ Q and, on the other hand, photoconductive organic substances. In view of the relatively high electrical conductivity mentioned and in terms of the mixing ratio with up to 30 percent by weight of photoconductor However, these compositions are not suitable for the recording material according to the invention, since they can be charged correctly or only very poorly because of a too high dark conductivity.

The structure of the recording material according to the invention is explained schematically in four variants with reference to the accompanying figures. Numeral 1 indicates the electrically conductive layer support, number 2 shows the charge generation layer, number 3 indicates the charge transport layer and number 4 indicates the adhesion-improving intermediate layer. Section 5 shows layers which represent a charge generation layer in dispersion. Numeral 6 shows a photoconductive layer of photoconductor as a charge-transporting compound, dye as a charge carrier-producing compound and binder, etc.

Aluminum foil, preferably also transparent, aluminum-vapor-coated polyester foil or aluminum-clad polyester foil with a thickness of up to 300 μm is preferably used as the electrically conductive layer support, but any other sufficiently conductive support material can also be used. The layer support can be a flexible endless belt, e.g. B. of nickel or steel, etc., _Q of a plate. According to the invention, a substrate is used which, as a band, is largely rigid transversely to the direction of travel and is flexible and dimensionally stable along the direction of travel. Besides one Metal strip, which already fulfills these conditions very well at thicknesses of 100-120 µm, uses in particular aluminum-coated polyester films of sufficient thickness, mainly in the range of 75-250 µm. It has been shown that the greater thickness of this substrate is necessary for the rigidity. Accordingly, a correspondingly greater flexibility is required from the applied coating. By welding, straps can be formed with layers as a layer carrier, which are necessary for use in high-speed copying machines.

The insulating intermediate layer 4 can consist of organic material or optionally also of a thermally, anodically or chemically produced aluminum oxide intermediate layer, and, in addition to promoting adhesion, has the aim, for example, of arranging the charge carrier injection from the layer carrier into the photoconductive layer in the dark. On the other hand, it does not hinder the flow of charge during the exposure process. Natural or synthetic resin binders can be used for the intermediate layer, such as, for example, polyamide resins, polyvinylphosphonic acid, polyurethanes or polyester resins. Their thickness can be up to 5 µm, while thicknesses of aluminum oxide layers are mostly in the range of 10 ² - 10 R.

zuzumischenden anorganischen Stoffe wie z. B. Teller bestimmen in besonderem Maße die spektrale Lichtempfindlichkeit der photoleitfähigen Schicht.Inorganic or organic substances such as those used as charge-generating compounds they are already known for this. This subheading includes dyes or amorphous selenium e.g. B. in the form of vapor deposition layers. The used

admixed inorganic substances such. B. plates particularly determine the spectral sensitivity of the photoconductive layer.

The application of a homogeneous, densely packed dye layer as a charge carrier generating layer is known and is obtained by evaporating the dye onto the carrier in vacuo. Depending on the vacuum setting, the dyes can be evaporated without decomposition under relatively favorable conditions (10 ^-3 - 10- ⁵ Torr, 250 - 400 ° C heating temperature). The temperature of the carrier is below 50 ° C.

Layers with densely packed dye molecules are obtained, which has the advantage that an optimal charge carrier generation rate is obtained in the dye layer, the high extinction of the dyes allowing a high concentration of excited dye molecules and that the charge transport through the densely packed dye layer does little through Binder can be hindered.

An advantageous layer thickness range of the evaporated dye is between 0.005 and 2 µm, but is particularly preferred between 0.005 and 1 _/ µm, since adhesive strength and homogeneity of the evaporated dye are particularly favorable here.

Depending on the type of use, the production of the charge carrier-producing layer with a uniform thickness can also be achieved by other coating techniques, for example by mechanically rubbing the finely powdered material into the electrically conductive layer carrier, by chemical deposition of a leuco base to be oxidized, by electrolytic or electrochemical processes or also by gun spray technique or by applying from a solution and drying the same.

In combination of the dyes with materials for the insulating intermediate layer or as a replacement for an intermediate layer, homogeneous, well covering dye layers with thicknesses of the order of 0.1-3 μm thickness are possible by dispersing the dyes also in a binder according to the invention and by coating the electrically conductive layer support ( Layer 5 in Fig. 4). The use of highly viscous cellulose nitrates is particularly advantageous, because during grinding a very good distribution of the pigments (small grain size) is achieved during the coating. The ratio of charge generating substance to binder can vary within wide limits. Pre-coatings with a dye content of more than 50% and a correspondingly high optical density are preferred. This achieves the use of dyes which are less thermally stable, such as, for example, azo or bisazo dyes, and at the same time have an adhesion-promoting effect.

• Perylen-3,4,9,10-tetracarbonsäureanhydrid bzw. Perylen-3,4,9,10-tetracarbonsäureimidderivate nach DT-OS 22 37 539,
• polynukleare Chinone nach DT-OS 22 37 678,
• cis- bzw. trans-Perinone nach DT-OS 22 39 923,
• Thioindigo-Farbstoffe nach DT-OS 22 37 680,
• Chinacridone nach DT-OS 22 37 679,
• Kondensationsprodukte aus Benzo-4,10-thioxanthen-3,1'- ' dicarbonsäureanhydrid und Aminen nach DT-OS 23 55 075,
• Phthalocyanin-Derivate nach DT-OS 22 39 924 und
• Farbstoffe, die durch Kondensation nach der Vorschrift Bull. Chem. Soc. Japan 25, 411 - 413 / 1952 aus Perlyen-3,4,9,10-tetracarbonsäureanhydrid und o-Phenylendiamin oder 1,8-Diaminonaphthalin hergestellt werden.

Dyes of various classes can be used as substances which generate charge carriers. For example:

• Perylene-3,4,9,10-tetracarboxylic anhydride or perylene-3,4,9,10-tetracarboximide derivatives according to DT-OS 22 37 539,
• polynuclear quinones according to DT-OS 22 37 678,
• cis or trans perinones according to DT-OS 22 39 923,
• Thioindigo dyes according to DT-OS 22 37 680,
• Quinacridones according to DT-OS 22 37 679,
• Condensation products from benzo-4,10-thioxanthene-3,1'- 'dicarboxylic acid anhydride and amines according to DT-OS 23 55 075,
• Phthalocyanine derivatives according to DT-OS 22 39 924 and
• Dyes, which by condensation according to the Bull. Chem. Soc. Japan 25, 411 - 413/1952 can be prepared from perlyene-3,4,9,10-tetracarboxylic anhydride and o-phenylenediamine or 1,8-diaminonaphthalene.

As mentioned, known, thin charge carrier-producing layers of inorganic substances, such as those obtained by vapor deposition of selenium, doped selenium, cadmium sulfide, etc. be produced, suitable.

In the photoconductive layer, particularly in the charge transport layer, charge transporting compounds are used as photoconductors. These are primarily organic compounds that have an extensive π electron system. These include both monomeric and polymeric aromatic or heterocyclic compounds.

The monomers used are in particular those which have at least one dialkylamino group or two alkoxy groups. Heterocyclic compounds such as oxdiazole derivatives according to DT-AS 10 58 836, such as 2,5-bis- (4'-diethylaminophenyl) -oxdiazole-1,3,4, have proven particularly useful. Other suitable monomers are, for example, triphenylamine derivatives, more highly condensed aromatic compounds such as pyrene, benzo-fused heterocycles, and also pyrazoline or imidazole derivatives according to DT-PS 10 60 714 and DT-PS 11 06 599; this subheading also includes triazole, thiadiazole and oxazole derivatives, as are known from German patents 10 60 260, 12 99 296, 11 20 875.

Formaldehyde condensation products with various aromatics such as, for example, condensates of formaldehyde and 3-bromopyrene in accordance with DT-OS 21 37 288 have proven themselves as polymers.

besteht vorzugsweise aus einem Gemisch einer Elektronen- donatorverbindun^g als Photoleiter mit einem Harzbindemittel, wenn das Aufzeichnungsmaterial negativ aufgeladen werden soll. Sie ist vorzugsweise transparent, was jedoch dann nicht notwendigerweise der Fall ist, wenn der elektrisch leitende Schichtträger transparent ist.

preferably consists of a mixture of an electron ^g donatorverbindun than photoconductor with a resin binder, when the recording material is to be negatively charged. It is preferably transparent, but this is not necessarily the case if the electrically conductive substrate is transparent.

The charge transport layer has a high electrical resistance and prevents the discharge of electrostatic charge in the dark. When exposed, it transports the generated charges, whereby it is assumed that, according to the invention, the polar (charged) excited state of the donor molecule is reduced and / or the nonpolar ground state is increased due to the increased polarity of the binder (electron-attracting nitro groups in cellulose nitrate).

In addition to the charge-generating and charge-transporting compounds, the added binder influences both the mechanical behavior such as abrasion, flexibility, film formation etc. and the electrophotographic properties such as photosensitivity, residual charge etc. According to DT-OS 23 53 639, previously film-forming compounds such as polyester resins, polyvinyl chloride / polyvinyl acetate copolymers, styrene-maleic anhydride copolymers, silicone resins, Reactive resins, DD lacquers, polycarbonates and acrylates or methacrylates etc. are used.

It has surprisingly been found that the use of cellulose nitrates instead of the binders used hitherto results in a substantial expansion and improvement in terms of elasticity and photosensitivity. This ensures that transport layers with highly viscous cellulose nitrates corresponding to the electrophotographic, but especially the mechanical requirements of a copying arrangement, eg. B. belt run with a narrow roller diameter, can be adjusted.

The viscosity is determined in Ubbelohde viscometers with different capillaries I - III at 25 ° C and a solids concentration of 10% (DIN 51 562). The viscosity of the binder batches in tetrahydrofuran is then well above 50 cSt.

The mixing ratio of the charge transporting compound to the binder can vary. However, the requirement for maximum photosensitivity, i. H. the largest possible proportion of charge-transporting compound and after avoiding crystallization thereof and increasing flexibility, d. H. as large a proportion of cellulose nitrate as possible, relatively certain limits.

bindungen läßt sich jedoch die Aufladung mit zunehmendem Gehalt sukzessiv verbessern und stabilisieren d. h. die Dunkelentladung wird verringert.Films with a high proportion of cellulose nitrates can also only be reduced to a low level on a conductive support.

bonds, however, the charge can be gradually improved and stabilized with increasing content, ie the dark discharge is reduced.

Flexibilität ungünstig, so daß bei besonders bevorzugten, flexiblen Ausführungsformen das Verhältnis Cellulosenitrat zu

Verbindung zwischen 30 bis 50 Gewichtsteilen auf 50 bis 70 Gewichtsteile liegt.Thereafter, the preferred cellulose nitrate content

Flexibility unfavorable, so that in particularly preferred, flexible embodiments, the ratio of cellulose nitrate to

Connection between 30 to 50 parts by weight to 50 to 70 parts by weight.

When using polymeric landing transport compounds, the cellulose nitrate proportions are in the lower range indicated.

The transport layers with monomers from charge-transporting compounds, such as 2,5-bis (4'-diethylaminophenyl) oxdiazol-1,3,4, are amorphous according to X-ray goniometer measurements.

The respective requirements of the recording material according to the invention for use in a copying machine can be adjusted by varying the viscosity of the photoconductive layer of the cellulose nitrate and in terms of the proportion of the charge-transporting compound are met within a wide range.

The layer thickness of the photoconductive layer is in a range which corresponds to a layer weight of approximately 5 to 50 g / m. In the case of the formation of the photoconductive layer as a charge carrier-generating layer and charge transport layer, layer thicknesses in the range from 0.005 to 2 μm, preferably 0.005 to μm or in the range from 2 to 20 μm, preferably 3 to 10 μm, are suitable. If the charge-generating layer is in dispersion, layer thicknesses in the range from 0.01 to 3 μm, preferably 0.1 to 1 μm, are suitable.

However, if the mechanical requirements as well as the electrophotographic parameters, such as charging and development station, of a copying machine permit, the specified limits can be extended upwards or downwards in individual cases.

In der folgenden Tabelle werden sie mit bekannten hochempfindlichen organischen Photoleiterschichten in ihrer Photoempfindlichkeit verglichen, wobei die vergleichbare Photoleiter-Doppelschicht-Anordnung eine ca. 150 mg/m² dicke Farbstoffauflage besitzt.Leveling agents such as silicone oils, wetting agents, in particular non-ionic substances, plasticizers of different compositions, such as, for example, based on chlorinated hydrocarbons or based on phthalic acid esters, are considered to be _“ customary _” additives according to the invention. If necessary, sensitizers and / or acceptors can also be added to the charge transport layer, however only to the extent that the optical

In the following table, they are compared with known, highly sensitive organic photoconductor layers in their photosensitivity, the comparable photoconductor double layer arrangement having an approximately 150 mg / m ² thick coating of dye.

• Zur Ermittlung der Hellentladungskurven bewegt sich die Meßprobe auf einem sich drehenden Teller durch eine Aufladevorrichtung hindurch zur Belichtungsstation, wo sie mit einer Xenonlampe XBO 150 der Firma Osram kontinuierlich belichtet wird. Ein Wärmeabsorptionsglas KG 3 der Firma Schott & Gen., Mainz, und ein Neutralfilter mit 15 % Transparenz sind der Lampe vorgeschaltet. Die Lichtintensität in der Meßebene liegt im Bereich von 70 - 170 µW/cm²; sie wird unmittelbar nach Ermittlung der Hellabfallkurve mit einem Opto-Meter Model -80 X (United Detector Technology Inc.) gemessen. Die Aufladungshöhe (U_o) und die photoinduzierte Hellabfallkurve werden über ein Elektrometer 610 CR der Fa. Kaithley Instruments, USA, durch eine transparente Sonde oszillographisch aufgezeichnet. Die Photoleiter- schicht wird durch die Aufladungshöhe (U_o) und diejenige Zeit (T 1/2) charakterisiert, nach der die Hälfte der Aufladung (U_o/2) erreicht ist. Das Produkt aus T_1/2 und der gemessenen Lichtintensität I [µW/cm²] ist die Halbwertsenergie E_1/2 [µJ/cm²].
  
  
  

The photosensitivity is measured as follows:

• To determine the light-discharge curves, the test sample moves on a rotating plate through a charging device to the exposure station, where it is continuously exposed to an XBO 150 xenon lamp from Osram. A heat absorption glass KG 3 from Schott & Gen., Mainz, and a neutral filter with 15% transparency are connected upstream of the lamp. The light intensity in the measuring plane is in the range of 70-170 µW / cm ² ; it is measured immediately after determining the light decay curve with an opto-meter model -80 X (United Detector Technology Inc.). The charge level (U _o ) and the photo-induced light decay curve are recorded oscillographically using a 610 CR electrometer from Kaithley Instruments, USA, using a transparent probe. The photoconductor layer is characterized by the charge level (U _o ) and the time (T 1/2) after which half the charge (U _o / 2) has been reached. The product of T _1/2 and the measured light intensity I [µW / cm ² ] is the half-value energy E _1/2 [µJ / cm ² ].
  
  
  

5 shows the curves of the spectral photosensitivity for the photoconductor layers listed in the table.

The very good photosensitivity of the material according to the invention is also evident here.

Example 2

A series of transport layers with differently viscous cellulose nitrates is applied to aluminum-vapor-coated polyester of 75 μm thickness with a dye layer evaporated thereon as indicated in Example 1, under comparable conditions in 8-10 μm thickness. The composition of the dried layers is a uniform 60 parts TO and 40 parts of the respective cellulose nitrate, which differs in its degree of viscosity and extends over a standard type range from 15 to 4 according to DIN 53 179.

These layers are checked for their mechanical properties in a cone test device ¹⁾ , adhesion on the layer support and formation of hairline cracks on the surface being assessed. While the adhesion of all layers is perfect, the formation of surface cracks of different lengths depends heavily on the viscosity of the cellulose nitrate used.

Example 3

According to Example 1, a dye layer is applied to polyester film 75, 125 and 190 µm thick, made conductive by a vapor-deposited aluminum layer. In each case a charge transport layer consisting of 65 parts by weight TO and 35 parts by weight of highly viscous cellulose nitrate is applied uniformly by coating and drying in a layer thickness range of 7.0 - 9.5 g / m2 under the same conditions.

The material is either glued or welded into a loop and subjected to a bending stress test. The flexible loop is often guided over roller diameters of different thicknesses. It is run over a drive rubber roller of approx. 80 mm ∅ as well as a replaceable steel roller with a diameter of 12, 18 or 25 mm as standard 5000 times, with a constant speed of rotation. As the roll diameter decreases and the substrate thickness increases, the photoconductor layer is exposed to an increased bending stress, so that hairline cracks can occur on the surface under this stress. This formation of hair cracks is advantageously observed in the dark under oblique angles.

For the top layer composition described, it has been shown that both 18 mm and 12 mm rolls pass through Knife and the specified layer thicknesses no hairline cracks occur under these strong bending stresses.

In contrast, in the known photoconductor layers with polyester resins or vinyl chloride / vinyl acetate copolymers as binders, a clear differentiation occurs both with regard to the layer thickness and the roller diameter, which is described below.

Analogously to the preparation described in these examples, a charge transport layer composition comprising 50 parts by weight of TO, 25 parts by weight of polyester resin and 25 parts by weight of vinyl chloride / vinyl acetate copolymer is applied in a layer thickness of 9-10 g / m ² to a dye layer according to Example 1 and subjected to the bending stress test. After that, no, on the micron with 125 thickness isolated short hair cracks and on the 190 _/ um thick polyester film very strong and long hair cracks do occur at 25 mm roller diameter and 5000 rounds in the photoconductive layer on polyester film of 75 microns thickness. In addition, occasional hairline cracks occur with a roller diameter of 18 mm and a carrier thickness of 75 μm.

Example 4

As indicated in Example 1, the following dyes and selenium are applied to aluminum-vapor-coated polyester film 75 μm thick in a layer thickness range of 100-200 mg / m ² .

To demonstrate the improved photoconductive properties in the presence of cellulose nitrates viscous different types are used together with TO and on the same carrier generation layers with _L adungs- transport layers compared to known binders such as polyester resins, copolymers of PVC / PVAc and TO.

Coating and drying (except for the selenium layer, which was dried for 3 minutes at 85 ° C) is carried out under comparable conditions (see Example 1), the thickness of the charge transport layer is 8-10 µm, the TO / binder weight ratio is 1: 1.

The measurement conditions of Example 1 also apply, the light intensity (xenon XBO 150) of one series of measurements being approximately 150 μW / cm ² , another 80-85 μW / cm ² and a charging range of 600-700 V being aimed for. In addition to the half-life, the residual charge is determined as an additional criterion for the photosensitivity, which is established after 0.1 seconds.

• 1 = TO/Cellulosenitrat steigend zu höher viskosen. TYPen von a) nach c)
• 2 = TO/Vinylchlorid/Vinylacetat-Copolymerisat
• 3 = TO/Polyesterharz

gilt.The series of measurements are summarized in the following table, whereby for the outer layers

• 1 = TO / cellulose nitrate increasing to higher viscosity. TYPES from a) to c)
• 2 = TO / vinyl chloride / vinyl acetate copolymer
• 3 = TO / polyester resin

applies.

Example 5

A according to DT-OS 21 37 288 condensation product prepared from 3-bromopyrene and formaldehyde has proved ^g as a polymeric charge transport compound ut. In combination with cellulose nitrate, the sensitivity can be significantly improved compared to known binders such as polyester resin.

A charge transport layer composed of 80 parts by weight of bromopyrene resin and 20 parts by weight of low-viscosity cellulose nitrate in a thickness of 6-7 μm is applied to a material coated in accordance with Example 1. In comparison, an analog material with a charge transport layer is produced from 80 parts by weight of bromopyrene resin and 20 parts by weight of polyester resin in a thickness of 6-7 μm.

The sensitivity measurement gives the following values:

Example 6.

100 _/ (optical quality) to thick polyester film, a charge transport layer of equal parts by weight of high viscosity and low viscosity respectively TO and cellulose nitrate in a coating thickness of 9 - applied 10 g / m ^2.

Meßspannung

werte von:

The measurement of the surface resistance by means of the tongue electrode (VDE 0303, part 3 / 3.67)

Measuring voltage

values of:

Example 7

Schicht wird gemäß Beispiel 1 die Farbstoffschicht aufgedampft und darauf eine Ladungstransportschicht aus 65 Gewichtsteilen TO und 35 Gewichtsteilen

(=̂ 6,3 µm) geschichtet und getrocknet. Das Material wird auf seine Dunkelentladung und auf seine Blitalicht- empfindlichkeit geprüft.To make a very flexible

Layer is evaporated according to Example 1 and then a charge transport layer of 65 parts by weight TO and 35 parts by weight

(= ̂ 6.3 µm) layered and dried. The material is checked for its dark discharge and for its sensitivity to light.

schaltet und die Dunkelentladung über 20 Sekunden gemessen. Eine Meßsonde registriert die Aufladung (U ) oder den Spannungsabfall (ΔU_D), der über einen Schreiber aufgezeichnet wird. Der Spannungsabfall im Dunkeln nach 2 Sekunden wird in dem interessierenden

gemessen:

The dark decay of a photoconductor sample is measured in a Dyntest-90 device (paper analyzer) from ECE, Gießen. For this purpose, the test sample is attached to a rotating disc (n = 139 ₀ rpm), where it is charged intermittently. After setting a certain charge, the charging

switches and the dark discharge is measured over 20 seconds. A measuring probe registers the charge (U) or the voltage drop (ΔU _D ), which is recorded by a recorder. The voltage drop in the dark after 2 seconds is in the one of interest

measured:

The discharge behavior during flash exposure is determined by mounting the sample on an aluminum plate, charging it and introducing it into the measuring station. Here the photoconductor layer is exposed through a transparent charge probe using a xenon short-arc lamp (Strobotac 1538-A flash lamp, General Radio). The charges measured with the charge probe are amplified and registered with a recorder.

Wavelength and light energy can be varied using interference and gray filters that can be inserted into the beam path. If the energy of the flash unit is constant, the light energy is determined directly after removing the photoconductor sample from the beam path (UDT-80 X optometer, see also Example 1).

wird die'Probe : einer definierten Blitzlicht- energie ausgesetzt (konst. Blitzdauer 3 _/us) und die Restladung nach 1 Sekunde bestimmt. Die Restladung U (_V) ist in Abhängigkeit von der Blitzlichtenergie E (µJ/cm²) in Fig. 6 (Kurve 1) gezeichnet. Aus diesen Kurven läßt sich die Halbwertsenergie (E_1/2) ermitteln, bei der sich die Photoleiterschicht bis zur Hälfte der Anfangsaufladung entladen hat. Danach besitzt die erfindungsgemäße Probe eine Halbwertsenergie E_1/2 = 1,7 /uJ/cm2 (U = (-) 675 V; elektrische Feldstärke 10,7 V/µm.After reaching a constant charge (field strength range 10 - 10.7

the sample is exposed to a defined flash energy (constant flash duration 3 _/ us) and the remaining charge is determined after 1 second. The residual charge U ( _V ) is drawn as a function of the flash light energy E (µJ / cm ² ) in Fig. 6 (curve 1). The half-value energy (E _1/2 ) at which the photoconductor layer has discharged up to half the initial charge can be determined from these curves. Thereafter, the sample according to the invention has a half-value energy E _1/2 = 1.7 / uJ / cm2 (U = (-) 675 V; electric field strength 10.7 V / µm.

teilen Polyesterharz und 25 Gewichtsteilen Vinylchlorid/ Vinylacetät-Copolymerisat besteht und dessen Schichtdicke 7 - 9 µm beträgt. Bei einer elektrischen Feldstärke von 10,2 V/ µm beträgt die Halbwertsenegie E_1/2 = 4,1 µJ/cm². Hieraus ist ersichtlich, daß die Photoempfindlichkeit der erfindungsgemäßen Anordnung wesentlich verbessert werden konnte. Die Restladungskurve ist in Fig. 6 unter 2 aufgezeichnet.By comparison, a photoconductive system was measured under the same conditions, the charge transport layer of 50 parts by weight TO, 25

parts of polyester resin and 25 parts by weight of vinyl chloride / vinyl acetate copolymer and whose layer thickness is 7-9 microns. With an electric field strength of 10.2 V / µm, the half-value energy E _1/2 = 4.1 µJ / cm ² . From this it can be seen that the photosensitivity of the arrangement according to the invention could be significantly improved. The residual charge curve is recorded in FIG. 6 under 2.

Example 8

der Dunkelentladung (U_o) von der Ladungen transportierenden Verbindung oder vom Gehalt an Cellulosenitrat in der Deckschicht dargestellt.In the following series of experiments the

the dark discharge (U _o ) from the charge-transporting compound or from the content of cellulose nitrate in the cover layer.

Tetrahydrofuran solutions with different TO contents in high-viscosity cellulose nitrate are flung onto a material coated with a dye as described in Example 1. The resulting layer thicknesses correspond to about 7 - 8 g / m ² .

The dark discharge is measured as described in Example 7.

Example 9

In an approximately 7% tetrahydrofuran solution consisting of 44 parts by weight of TO and 36 parts by weight of desensitized cellulose nitrate (weight ratio cellulose nitrate / n-BuOH 65/35) are in about 1% (0.7 g) or 5% amount (based on Solids content) dye suspended according to Example 1.

For dispersion in a ball mill (Perl Mill PM 1, Draiswerke, Mannheim), the batch is first adjusted to a 25% concentration and the dye is intensively ground for 2 hours. This solution was then diluted to the spreading composition indicated above and the dye-dispersion layer according to the arrangement in FIG. 1 was homogeneously layered on an aluminum-vaporized 75 μm thick polyester film in a layer thickness of approximately 7 g / m ² and dried.

The measurement is carried out analogously to the measurement method given in Example 1 (light intensity approx. 90 µW / cm ² , Xenon XBO 150):

Example 10

Perinon-Farbstoff (Hostapermorange GR) in Tetrahydrofuran während 2 Stunden intensiv vermahlen. Nach Dispergieren wird die Lösung auf das Vierfache verdünnt und die ca. 1 %ige Beschichtungslösung auf

bedampfte 75 µm dicke Polyesterfolie homogen geschichtet und getrocknet.It is an approach from equal parts by weight of desensitized, highly viscous cellulose nitrate

Intensively grind the Perinon dye (Hostapermorange GR) in tetrahydrofuran for 2 hours. After dispersing, the solution is diluted four times and the approx. 1% coating solution

steamed 75 µm thick polyester film layered homogeneously and dried.

After drying, the layer thickness of this pigment precoat corresponds to 255 mg / m ² and 50 mg / m, the composition pigment / cellulose nitrate 60/40. A charge transport layer composed of 65 parts by weight of TO and 35 parts by weight of highly viscous cellulose nitrate is applied and dried uniformly to the differently thick pigment precursors with a layer weight of approximately 8 g / m2.

The sensitivity is determined analogously to Example 1 (light intensity approx. 85 μW / cm ² ; Xenon XBO 150).

Example 11

A pigment precoat from 2 parts by weight of a polynuclear quinone (Hostapermscharlach GO) and one part by weight-phlegmatized high viscosity cellulose nitrate is prepared analogously to Example 1 dispersed ₀ and pre-coated on an appropriate carrier in a different layer thickness. A layer corresponding to a layer weight of approximately 7 g / m ² and a composition of 70 parts by weight TO and 30 parts by weight of low-viscosity cellulose nitrate is layered thereon.

The measurement of the photosensitivity according to Example 1 gives the following values for the differently thick pigment primers (light intensity: 80 µJ / cm ² ; Xenon XBO 150):

Example 12.

letten Farbstoffschicht beträgt 195 mg/m².A condensation product from the reaction of perylene-3,4,9,10-tetracarboxylic anhydride and o-phenylenediamine according to DT-OS 23 14 051, vapor-deposited aluminum-vapor-coated polyester film is evaporated to 190 analogously to Example 1. The layer weight of the homogeneous,

Lat dye layer is 195 mg / m ² .

(hochviskos) geschichtet. Eine zum Vergleich hergestellte Schicht mit einem Vinylchlorid/Vinylacetat-Copolymerisat (PVC/PVAc) liefert ein relativ unempfindliches System auf der gleichen Farbstoffaufdampfschicht.Layers of 65 parts by weight TO and. 35 parts by weight

(highly viscous) layered. A layer made for comparison with a vinyl chloride / vinyl acetate copolymer (PVC / PVAc) provides a relatively insensitive system on the same dye vapor deposition layer.

The photosensitivity is measured analogously to Example 1 (light intensity: 90 uW / cm ²

Claims (10)

1. Electrophotographic recording material composed of an electrically conductive support, optionally an insulating intermediate layer and a photoconductive layer comprising at least one charge-generating and charge-transporting compound, binder and conventional additive-containing layer, characterized in that the recording material has a 75 to 250 µm thick support worked as a photoconductor tape is so flexible that it repeatedly tends to roll over at least 12 mm in diameter, does not tend to hairline cracks and that it contains a cellulose nitrate as a binder, which has a viscosity of 400 - 25 cPoises at concentrations between about 4 and 12 percent in 5% aqueous acetone according to DIN 53 179 (standard type 4 - 12). 2. Recording material according to claim 1, characterized in that the cellulose nitrate has a viscosity of 400 ⁺ 25 cPoises at concentrations between about 4 and 9 percent in 5% aqueous acetone according to DIN 53 179 (standard type 4-9). 3. Recording material according to claims 1 and 2, characterized in that the ratio of cellulose nitrate to. Charge transporting connection in the range between 20 to 60 parts by weight to 40 to 80 parts by weight. 4. Recording material according to claims 1 to 3, consisting of a, in the order of the layers 100 to 250, thick, electrically conductive layer support made of aluminum vapor-coated polyester film, a charge-generating dye layer of 0.005 - 2, by thickness and a 2 - 20 _/ um thick Charge transport layer composed of 40 to 80 parts by weight of a monomeric organic charge-transporting compound and 20 to 60 parts by weight of cellulose nitrate as a binder. 5. Recording material according to claim 4, made of a 100 to 250, thick, electrically conductive layer support made of aluminum vapor-coated polyester film, a charge, the dye layer of 0.005 - 1, thick and a 3 to 10, thick charge transport layer of 50 to 70 Parts by weight of a monomeric organic charge transporting compound and 30 to 50 parts by weight of cellulose nitrate as a binder. 6. Recording material according to claim 1, characterized in that; that the charge-generating layer contains cellulose nitrate. 7. Recording material according to claim 1, characterized in that the photoconductive layer contains as charge-transporting compound at least one monomeric or polymeric aromatic or heterocyclic compound. 8. Recording material according to claim 7, characterized in that the photoconductive layer is a monomeric contains heterocyclic compound which is substituted by at least one dialkylamino group. 9. Recording material according to claim 7 and 8, characterized in that the heterocyclic compound is an oxdiazole. 10. Recording material according to claim 9, characterized in that the heterocyclic compound is 2,5-bis (4'- diethylaminophenyl) oxdiazole-1,3,4.

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