EP0231835B1 - Electro photographic recording material - Google Patents

Description

The present invention relates to an electrophotographic recording material composed of an electrically conductive layer support, optionally an adhesion-promoting insulating intermediate layer and at least one binder-containing photoconductive layer which contains a charge-generating compound and a pyrazoline derivative as charge-transporting compound.

The invention particularly relates to a recording material in which the photoconductive layer consists of a charge generation and charge transport layer.

The recording material according to the invention is also suitable for a lithographic printing form or printed circuit which can be produced by electrophotographic means if it consists of a correspondingly suitable electrically conductive layer support and a photoconductive layer with binders which can be stripped of alkali.

The use of 1.3.5.-triphenyl-pyrazoline and 1.5-diphenyl-3-styryl-pyrazoline derivatives as photoconductors is known. Thus, in DE-PS 1 060 714 corresponding to US-PS 3,180,729, these compounds are described in a monolayer arrangement with homogeneous dye sensitization, for example by adding rhodamines, particularly with binders that can be stripped of alkaline agents, or in an electrophotographic element of the laminate type (DE-A 29 31 447) .

This leads to little photosensitive and unsuitable photoconductor layers for copying purposes.

DE-PS 22 20 408 corresponding to US Pat. No. 3,973,959 specifies the use of pyrazoline derivatives as charge transport compounds in photoconductor layers.

It is also known from the US patents Nos. 3,837,851, 4,030,923, 4,307,167 and 4,490,452 the use of preferably 1,5-diphenyl-3-styrylpyrazoline derivatives which have electron-donating substituents such as methoxy, ethoxy, dimethylamino and diethylamino groups in the p-position of the 3-styryl and 5-phenyl group . The 1-phenyl-3 [(p-diethylaminostyryl) -5 (p-diethylaminophenyl)] pyrazoline is preferably used in the transport layers.

Similar pyrazoline derivatives in photoconductor layers are also known from US Pat. No. 4,278,746. Analog compounds are also described in U.S. Patent 4,315,982.

Disadvantages of the known pyrazoline derivatives are their sometimes poor yield in their preparation and their difficult preparative accessibility over several reaction stages.

In DE-PS 32 46 036 corresponding to US Pat. No. 4,567,125, 1,5-diphenyl-3 p-methoxyphenyl pyrazoline and 1-phenyl-3 p-methylstyryl-5-p-tolylpyrazoline are also described in charge transport layers; the latter compound already tends to crystallize out after film formation, moreover its adhesion and its photosensitivity are still unsatisfactory.

The object of the present invention was therefore to create a highly light-sensitive, electrophotographic recording material from preparatively very easily accessible photoconductor compounds of the pyrazolines, which adheres very well with high flexibility and has a very low sensitivity to pre-exposure.

in der n = Null oder 1 und R₁, R₂, R₃, R₄, R₅ = Wasserstoff oder Halogen darstellen, wobei mindestens einer dieser Substituenten Halogen bedeutet, bevorzugt Chlor oder Brom.The solution to this problem is based on an electrophotographic recording material of the type mentioned at the outset and is characterized in that the charge-transporting compound corresponds to the general formula I:

in which n = zero or 1 and R₁, R₂, R₃, R₄, R₅ = hydrogen or halogen, at least one of these substituents being halogen, preferably chlorine or bromine.

The compounds in which R₁ and R₂, ₃ are hydrogen and R₄, respectively. R₅ Are halogen, chlorine and bromine being preferred, such as 1,3-diphenyl-5- (2-chlorophenyl) pyrazoline or 1,3-diphenyl-5- (2,4-dichlorophenyl) pyrazoline.

It can also be R₁ = hydrogen and R _2.3 and R _4.5 = halogen, as indicated in the attached formula table I.

Of the styrylpyrazoline derivatives with n equal to 1, compounds are preferably used in which R₁ = hydrogen and RR _2.3 and R _4.5 = halogen. The ortho position of the halogen, in particular chlorine, substituents, such as 1-phenyl-3- (2-chlorostyryl) -5- (2-chlorophenyl) pyrazoline or 1-phenyl-3- (2,4- dichlorostyryl) -5- (2,4-dichlorophenyl) pyrazoline.

The charge-transporting compounds of the general formula I can furthermore be halogen-substituted in the phenyl substituent in the 1-position.

The preparation of the compounds which can be used according to the invention is generally known and is carried out analogously to the information in DE-PS 10 60 714 corresponding to US Pat. No. 3,180,729.

They are very easily accessible by condensation of preferably Cl- and / or Br-substituted benzalacetophenone or dibenzolacetone derivatives with phenylhydrazines in acetic acid (99-100%). Furthermore, the starting materials are cheap and the compounds can be produced in high yield.

In addition to their photoconductor properties, the pyrazoline derivatives according to the invention are exceptionally strongly fluorescent (λ _FL ∼500 nm) and can therefore also be used as fluorescent dyes, “laser dyes” and as optical brighteners, for example of PVC plastics.

The charge transport compounds according to the invention have very good film formation with various binders and an extraordinarily low tendency to crystallize, even at a relatively high concentration. The films remain flexible and adhere very well, even in a double-layer arrangement.

The very low pre-exposure sensitivity and very high photosensitivity of double layers with these charge-transporting compounds was surprising. A number of pigments can be used as charge generation layers; condensation products of perylene-3.4.9.10.-tetracarboxylic acid dianhydride with alkylamines, arylamines, aralkylamines and o-aryldiamines, as indicated in the attached formula table II, are particularly advantageous for this purpose.

Furthermore, a significantly improved residual discharge behavior of the layers, in particular in the case of styrylpyrazoline derivatives (e.g. formulas 5 + 6), has proven to be advantageous.

By adding certain electron acceptor compounds such as 9-bromanthracene, the residual discharge level and Improve consistency even more, especially in cyclical behavior. The ability to activate the charge-transporting compounds with halogenated anthracene or acridine derivatives in the 9 or 10 position is particularly advantageous.

The structure of the electrophotographic recording material is explained schematically with the aid of the attached FIGS. 1 to 4. Position 1 indicates the electrically conductive layer support, position 2 indicates the layer generating the charge carrier, and position 3 indicates the layer carrying the charges. Position 4 shows an adhesion-promoting, insulating intermediate layer, and position 5 shows layers which indicate a charge-generating layer as a pigment layer in dispersion, for example with a binder. Position 6 shows a photoconductive monolayer of dispersed pigment, photoconductor and binder. This arrangement according to Figure 1 is advantageous for the production of printing forms by electrophotography.

Aluminum foil, optionally transparent, aluminum-coated, sputtered or aluminum-clad polyester foil, is preferably used as the electrically conductive layer support, but any other sufficiently conductive support material can also be used. The arrangement of the photoconductive system can also be on a drum, on flexible endless belts, for example made of nickel or steel etc., or on plates (for example made of aluminum).

All materials known for this purpose, such as aluminum, zinc, magnesium, copper plates or multi-metal plates, can be used as layer supports for the electrophotographic production of printing forms or printed circuits. Surface-coated aluminum foils have proven particularly useful. The surface finish consists of a mechanical or electrochemical roughening and, if necessary, a subsequent anodization and treatment with polyvinylphosphonic acid.

The introduction of an adhesion-promoting insulating intermediate layer, optionally also a thermally, anodically or chemically produced aluminum oxide intermediate layer (FIG. 3, position 4), has the aim of reducing the charge carrier injection from the metal into the photoconductor layer in the dark. On the other hand, it should not hinder the flow of charge during the exposure process. The intermediate layer acts as a barrier layer, it also serves to improve the adhesion between the layer support surface and the pigment layer and the photoconductor layer and should be able to be stripped off water or alcohol-alkaline for the production of printing forms.

Different natural or synthetic resin binders can be used for the intermediate layer, however, preference is given to using materials which are good on one Metal, especially aluminum surface, adhere and are slightly dissolved when subsequent layers are applied. These include polyamide resins, polyvinyl alcohols, polyvinylphosphonic acid, polyurethanes, polyester resins, furthermore polycarbonates, phenoxy resins, cellulose nitrates, vinyl chloride-vinyl acetate copolymers, also copolymers of styrene and butadiene, (meth) acrylic acid esters and maleic anhydride.

Binders such as polycarbonates, polyester resins and especially vinyl chloride-vinyl acetate copolymers, which are also present in the charge transport layer, have proven particularly useful.

The thickness of organic intermediate layers can be up to 5 μm, that of an aluminum oxide intermediate layer is generally in the range from 0.01 to 1 μm.
Organic intermediate layers in this thickness range are also preferably applied.

Layer 2 or 5 (FIGS. 2 to 4) has the function of a layer generating charge carriers; the pigment used determines the spectral photosensitivity of the photoconductive system through its absorption behavior.

The following pigments can advantageously be used:
Perylene-3.4.9.10.-tetracarboxylic acid dianhydride as well as ∼ diimide derivatives (for example Formula Table II, AC), bis-benzimidazole pigments such as cis and trans-perinones (for example formulas E, F), furthermore perylene-3.4.9.10.-tetracarboxylic acid benzimidazole derivatives (for example formula D), quinacridone and dioxazine derivatives, polynuclear quinones, for example 4.10-dibromoanthanthrone ( Formula G, CI 59.300), flavanthrone etc., indigo and thioindigo pigments, benzothioxanthene derivatives according to DE-OS 23 28 727 (for example formula H), phthalocyanines (metal-containing CI 74.160 and metal-free CI 74.250), for example ε-Cu phthalocyanine etc., mono-, bis- and trisazo pigments, Squarilium dyes.

The application of a homogeneous, densely packed pigment layer is preferably obtained by evaporating the pigment onto the support in vacuo. Depending on the vacuum setting, the dye can be evaporated without decomposition under conditions of 1.33 × 10⁻⁶ to 10⁻⁸ bar and 240 to 290 ° C heating temperature. The temperature of the substrate is below 50 ° C. This gives layers with tightly packed dye molecules. This is advantageous over all other possibilities of producing very thin, homogeneous layers in that an optimal charge generation rate can be obtained in the pigment layer.

The extremely finely dispersed distribution of the pigment enables a large concentration of excited dye molecules that inject charges into the transport layer. In addition, the charge transport through the pigment layer is not or only slightly hampered by binders. An advantageous layer thickness range of the vapor-deposited pigment is between 0.005 and 3 μm. A thickness range between 0.05 and 1.5 μm is particularly preferred since the adhesive strength and homogeneity of the vapor-deposited pigment are particularly favorable here.

In addition to vapor deposition, a uniform pigment layer thickness can also be achieved by other coating techniques. This subheading includes mechanical rubbing of the finely powdered material into the electrically conductive substrate, electrolytic or electrochemical processes or electrostatic spray technology.

Well covering pigment layers with thicknesses of the order of 0.05 to 3 µm can also be obtained by grinding the pigment with binders, in particular with cellulose nitrates, epoxy resins, PVC / PVAC copolymers, styrene-maleic anhydride copolymers, polymethacrylates, polyvinyl acetates, polyurethanes, polyvinyl butyrals, polyvinyl carbonates Polyesters etc. as well as their mixtures and subsequent coating of these dispersions according to position 5 in FIG. 4 are produced. Thermal post-crosslinking binder systems such as reactive resins (DD lacquers) can also be used.

The pigment / binder ratio can vary within wide limits, but preference is given to pigment primers with a pigment content of over 50% and a correspondingly high optical density.

The charge-transporting layer 3 with the charge transport compounds according to the invention is preferably transparent and, without the pigment layer, has practically no photosensitivity in the visible range (450 to 750 nm). It consists of a mixture of an electron donor compound (organic photoconductor) with a binder. Layer 3 has a high electrical resistance of greater than 10 12 Ω. It prevents the flow of the preferably negative electrostatic charge in the dark; when exposed, it transports the charges generated in the pigment layer.

The mixing ratio of the charge transporting compound to the binder can vary. However, the requirement for maximum photosensitivity, that is to say the largest possible proportion of charge-transporting compound, and to avoid crystallization to be avoided and increase in flexibility, that is to say the largest possible proportion of binders, set relatively certain limits. A mixing ratio of about 1: 1 parts by weight has generally proven to be preferred, but ratios between 4: 1 and 1: 4 are also suitable. The surprisingly low tendency towards crystallization of a number of the charge transport compounds according to the invention also permits organic photoconductor / binder ratios of 4: 1, in particular with polycarbonate, without crystallization taking place and the film-forming properties deteriorating.

It has also been shown that these highly sensitive photoconductive systems can be improved in their residual discharge properties by adding electron acceptor compounds. The acceptors bring about a reduction in the residual discharge in the photoconductive system and also an improved constancy of the cyclic parameters, without the other good electrophotographic properties such as photosensitivity, charge acceptance, dark decay, pre-exposure sensitivity etc. being impaired. They are preferably contained in the charge transport layer in an amount of up to 10 percent by weight, based on the total coating.

in der

X -

Wasserstoff, Halogen, wie Chlor, Brom, Jod, die Cyanogruppe und

Y -

Stickstoff oder die Gruppierung

mit

Z -

Halogen, wie Chlor oder Brom, oder die Cyanogruppe

bedeuten. Bevorzugt einsetzbare Verbindungen sind 9,10-Dibromanthracen, 9,10-Dichloranthracen, 9-Chloranthracen, 9-Bromanthracen oder 9-Chloracridin.The photoconductive system preferably has, as electron acceptor compound, an anthracene or acridine which is substituted in the 9- and / or 10-position and has the following structure:

in the

X -

Hydrogen, halogen, such as chlorine, bromine, iodine, the cyano group and

Y -

Nitrogen or the grouping

With

Z -

Halogen, such as chlorine or bromine, or the cyano group

mean. Compounds which can be used with preference are 9,10-dibromoanthracene, 9,10-dichloroanthracene, 9-chloroanthracene, 9-bromoanthracene or 9-chloroacridine.

Advantageous charge transport layers are composed of approximately 50-70 percent by weight charge transport compound, 20-40 percent by weight polycarbonate, approximately 10 percent by weight vinyl chloride-vinyl acetate copolymer and up to 6 percent by weight electron acceptor compound. With these settings, optimal copy quality is achieved even at higher temperatures and humidity. In addition, the pre-exposure sensitivity is surprisingly low.

In addition to the charge generation and transport materials described, the added binder influences both the mechanical behavior, such as abrasion, flexibility, film formation, adhesion, etc., and to a certain extent the electrophotographic behavior, such as photosensitivity, residual charge and cyclical behavior under normal conditions, as well as under higher conditions Temperature (20 to 50 ° C) and humidity (greater than 80% relative humidity).

Polyester resins, polyvinyl acetates, polycarbonates, silicone resins, polyurethanes, epoxy resins, phenoxy resins, poly (meth) acrylates and copolymers (for Example with styrene), polystyrenes and styrene copolymers (for example with butadiene), cellulose derivatives, such as cellulose acetobutyrates etc., are used. The photoconductive layer preferably contains polyester resins, vinyl chloride-vinyl acetate copolymers, polycarbonates or mixtures thereof as binders. For the production of printing forms or printed circuits, the photoconductive layer contains an alkali-strippable binder.

Styrene-maleic anhydride copolymers, sulfonyl urethanes, phenolic resins or copolymers of vinyl acetate with an unsaturated carboxylic acid are preferably used as alkali-releasable resins.

In addition, thermally post-crosslinking binder systems such as reactive resins, which are composed of an equivalent mixture of hydroxyl-containing polyesters or polyethers and polyfunctional isocyanates, polyisocyanate-crosslinkable acrylate resins, melamine resins, unsaturated polyester resins, etc., have been used successfully.

Furthermore, polyvinyl chloride, copolymers of vinyl chloride and vinyl acetate, polyvinylidene chlorides, polyacrylonitriles and cellulose nitrates can be used, in particular also blended with the above binders; a proportion of up to about 10 percent by weight, based on the solids content of the charge transport layer, has proven to be advantageous.

The layer thickness is also important for the optimal photosensitivity of the charge transport layer: layer thicknesses between approximately 2 and 25 µm are generally used. A thickness range of 5 to 18 μm has proven to be advantageous. However, if the mechanical requirements and the electrophotographic parameters allow for charging, exposure and development processes, the specified limits can be extended upwards or downwards on a case-by-case basis.

Leveling agents, such as silicone oils, wetting agents, in particular nonionic substances, plasticizers of different compositions, such as, for example, those based on chlorinated hydrocarbons or those based on phthalic acid esters are considered to be customary additives.

The invention is explained in more detail with the aid of the examples, without being restricted thereto.

Examples:

• 1. 1,3-Diphenyl-5(2-chlorphenyl)pyrazolin (Formel 1 der Formeltabelle I)
• 2. 1,3-Diphenyl-5(4-chlorphenyl)pyrazolin (Formel 3), sowie
• 3. 1,3-Diphenyl-5(2,4-dichlorphenyl)pyrazolin (Formel 4) in 9 - 10 µ Trockenschichtdicke aufgetragen.
  Zum Vergleich wird in gleicher Weise eine Schicht mit der Ladungstransportverbindung
  2,5-Bis(4-diethylaminophenyl)oxdiazol-1.3.4 (TO)
  hergestellt.

Die Photoempfindlichkeit dieser Photoleiter-Doppelschichten wird wie folgt vermessen (Halogen-W-Lampe, Belichtungsintensität ca. 3,5 µW/cm²):
Zur Ermittlung der Hellentladungskurven wird die Meßprobe durch eine Aufladevorrichtung zur Belichtungsstation bewegt, wo sie mit einer Halogen-W-Lampe (150 W) kontinuierlich belichtet wird. Ein Wärmeabsorptionsglas und ein Neutralfilter sind der Lampe vorgeschaltet. Die Lichtintensität in der Meßebene liegt vorwiegend im Bereich von 3 - 10 µW/cm²; sie wird parallel zum Meßvorgang mit einem Optometer gemessen. Die Aufladungshöhe und die photoinduzierte Hellabfallkurve werden über ein Elektrometer durch eine transparente Sonde oszillografisch aufgezeichnet. Die Photoleiterschicht wird durch die Aufladungshöhe (U_o) und diejenige Zeit (t) charakterisiert, die zum Erreichen der Hälfte, eines Viertels und eines Achtels der ursprünglichen Aufladung (U_o) erforderlich ist. Das Produkt aus dem jeweiligen t [s] und der parallel gemessenen Lichtintensität [µW/cm²] führt zu den charakteristischen Energiemengen [µJ/cm²] wie zum Beispiel der Halbwertsenergie E_1/2. Die Energiemengen, bei denen 1/8 der Anfangsaufladung (U_o) erreicht wird, dienen zur Charakterisierung des Restentladungsverhaltens einer Photoleiterschicht. Die Restladung U_E, vorwiegend nach 1 oder 3 s gemessen, ist ebenfalls ein Maß für das Restentladungsverhalten.

2. Auf eine mit Polycarbonat vorbeschichtete Al/PET-Folie wird wie in Beispiel 1 N,N′-Dimethylperylimid (Formel A) bedampft.
Darauf werden THF-Lösungen aus gleichen Gewichtsteilen Polyesterharz (Dynapol L 206 der Hoechst AG) und

• 1. 1,3-Diphenyl-5(2-bromphenyl)-pyrazolin (Formel 1)
• 2. 1,3-Diphenyl-5(2-fluorphenyl)-pyrazolin (Formel 1)
• 3. 1,3-Diphenyl-5(2-chlorphenyl)-pyrazolin (Formel 1)
• 4. 1,3-Diphenyl-5(3-chlorphenyl)-pyrazolin (Formel 2)
• 5. 1,3-Diphenyl-5(4-chlorphenyl)pyrazolin (Formel 3)

in etwa 10 µm Dicke nach Trocknung aufgetragen.
Die Messung der Photoempfindlichkeit erfolgt gemäß Beispiel 1 (Hal/W. Lampe, Belichtungsintensität 3,5 - 3,8 µW/cm²):

3. Auf eine Ladungserzeugungsschicht wie in Beispiel 2 beschrieben, werden THF-lösungen aus gleichen Teilen Polycarbonat und

• 1. 1-Phenyl-3(2-chlorstyryl)-5(2-chlorphenyl)pyrazolin (Formel 5),
• 2. 1-Phenyl-(2,4-dichlorstyryl)-5(2,4-dichlorphenyl)-pyrazolin (Formel 6),
• 3. 1,5-Diphenyl-3-styryl-pyrazolin,
• 4. 1-Phenyl-3(4-methylstyryl)-5(4-tolyl)-pyrazolin sowie
• 5. 1,5-Diphenyl-3(4-methoxyphenyl)pyrazolin

geschichtet und anschließend bei 90 - 100 °C in einem Umlufttrockenschrank g etrocknet.
Desgleichen werden weitere Transportschichten aus 50 Gewichtsteilen Ladungstransportverbindung Formeln 1 - 5, 47 Gewichtsteilen Polycarbonat und 3 Gewichtsteilen 9-Bromanthracen (MBA) jeweils auf die Pigmentschicht gebracht.
Die ca. 10 µm dicken Photoleiter-Doppelschichten werden wie in Beispiel 1 vermessen (Belichtungsintensität 4,3 - 5,0 µW/cm²): Phl-Schicht Akzeptorzusatz (-)U_o/V E_1/2 E_1/8 (-)U_E/V (nach 3 s) 1 - 500 1.02 2.85 19 2 - 520 1.07 2.93 15 3 - 490 1.19 3.6 27 4 - 500 1.44 4.22 19 5 - 485 1.65 6.15 35 1' MBA 530 0.82 2.15 11 2' MBA 505 0.85 2.23 15 3' MBA 480 1.08 2.91 23 4' MBA 485 1.3 3.83 23 5' MBA 480 1.26 3.54 17 Die Photoleiterschichten mit den Ladungstransportverbindungen 3, 4 und 5 dienen zu Vergleichszwecken.
4. Auf einen mit Polycarbonat vorbeschichteten leitfähigen Schichtträger wird kontinuierlich im Vakuum N,N′-Dimethylperylimid (Formel A) bedampft, so daß die Pigmentschichtdicke ca. 130 mg/cm² beträgt. Darauf werden Lösungen folgender Ladungstransportschichten aufgetragen:

• a) 50 Gewichtsteile Formel 5, 47 Gewichstteile Polycarbonat (Makrolon 3200) und 3 Gewichtsteile MBA sowie
• b) 50 Gewichtsteile Formel 5, 47 Gewichtsteile Vinylchlorid-Vinylacetat Copolymerisat (Hostaflex M 131) und 3 Gewichtsteile MBA.

Nach Beispiel 1 wird folgende Photoempfindlichkeit gemessen (Hal. W. Lampe; Belichtungsintensität ∼3,5 µW/cm²):

Außerdem kann in der beschriebenen Meßanordnung das zyklische Verhalten (zyklisches Verh.) durch Messung der 1. sowie 5. gegebenenfalls weiteren Hellentladungen ermittelt werden.
Die Vorbelichtungsempfindlichkeit (Vorbel.empf.) wird durch Messung der Hellentladung am Anfang, Belichtung der Photoleiterschicht unter einer Leuchtstoffröhre mit ca. 10⁴ lx während 1 Minute, der sich eine ebenso lange Lagerzeit im Dunkeln anschließt und danach folgender Hellentladungsmessung bestimmt.
Die Änderung der elektrophotographischen Daten dieser Photoleiter-Schichten unter den angegebenen Bedingungen ist nach der Tabelle sehr gering.
Die spektrale Photoempfindlichkeit der hergestellten Doppelschicht wird unter Vorschaltung von Filtern nach der in Beispiel 1 angegebenen Methode bestimmt: Bei negativer Aufladung (500 - 550 V) wird durch Belichten die Halbwertszeit (t_1/2 in msec) für den jeweiligen Wellenlängenbereich ermittelt. Durch Auftragen der reziproken Halbwertsenergie 1/E_1/2 (cm²/µJ) gegen die Wellenlänge λ(nm) erhält man die spektrale Photoempfindlichkeitskurve. Dabei bedeutet die Halbwertsenergie E_1/2 (µJ/cm²) diejenige Lichtenergie, die eingestrahlt werden muß, um die Schicht auf die Hälfte der Anfangsspannung U_o zu entladen.
Die spektrale Photoempfindlichkeit der Doppelschicht a) geht aus Figur 5 hervor, Aufladung (-) 490 - 520 V.
5. Eine Ladungen erzeugende Schicht nach Beispiel 1 wird mit einer THF-Lösung aus 40 Gewichtsteilen Polycarbonat und 60 Gewichtsteilen Photoleiterverbindung

• A) 1,3-Diphenyl-5(2-chlorphenyl)pyrazolin (Formel 1)

in 10 µm Dicke nach Trocknung beschichtet.
Außerdem werden Transportschichten der Zusammensetzung 60 Gewichtsteile Photoleiterverbindung, 37 Gewichtsteile Polycarbonat (Makrolon 3200) und 3 Gewichtsteile Elektronenakzeptor-Verbindung in ca. 10 µm Dicke auf die Pigmentschicht gebracht. Als Akzeptoren wurden die halogenierten Anthracen-Derivate

• 1. 9-Bromanthracen (MBA)
• 2. 9-10-Dibromanthracen (DBA) sowie
• 3. 9-10-Dichloranthracen (DCA) eingesetzt.

Die Ergebnisse der Photoempfindlichkeitsvermessung sind in der folgenden Tabelle zusammengefaßt (Belichtungsintensität 3,8 - 4,7 µW/cm²):

Bei der Schicht A (Formel 1) läßt sich durch Akzeptorzusätze besonders das Restentladungsverhalten verbessern.
6. Eine Pigmentpräparation Hacolor # 50915 (Fa. Hagedorn, Osnabrück) bestehend aus 70 Gewichtsteilen ε-Cu-Phthalocyanin (CI 74160 : 6) und 30 Gewichtsteilen Cellulosenitrat, wird auf eine Aluminium bedampfte Polyesterfolie (Al/PET-Folie) in 310 mg/m² Dicke beschichtet. Darauf wird eine Lösung aus 70 Gewichtsteilen Styrylpyrazolin-Derivat (Formel 5), 37 Gewichtsteilen Polycarbonat und 3 Gewichtsteilen MBA in 11 sowie 14 µm Dicke aufgetragen.
Die Photoempfindlichkeit wird gemäß Beispiel 1 bestimmt und die spektrale Photoempfindlichkeit der dünneren Beschichtung ist bei einer Aufladung von ca. (-) 180 V in Figur 6 aufgezeichnet.

7. Zu einer Lösung mit 40 Gewichtsteilen Formel 5, 50 Gewichtsteilen Copolymerisat aus Styrol und Maleinsäureanhydrid (Scripset 550 der Hoechst AG), 5 Gewichtsteilen 9-Bromanthracen in Tetrahydrofuran werden 5 Gewichtsteile N,N′-Dimethylperylimid (Formel A) gegeben und in einer Kugelmühle währen 2,5 Stunden sehr fein vermahlen. Anschließend wird die Pigmentdispersion auf eine oberflächlich drahtgebürstete Aluminiumfolie in ca. 5 µm Dicke geschichtet.
In gleicher Weise werden monodisperse Schichten aus 45 Gewichtsteilen der Verbindung Formel 5, 50 Gewichtsteilen Scripset 550 sowie 5 Gewichtsteilen Pigment folgender Art

• 2. Hostapermorange GR (Formel E, trans-Perinon)
• 3. Hostapermscharlach GO (Formel G, C.I. 59300) sowie
• 4. Benzothioxanthen-3,4-dicarbonsäureimid-(N,N′-mononitrophenylen-1,2)-imidin-(3) (Formel H, V 525M)

hergestellt.
Die Vermessung der Photoempfindlichkeit nach Beispiel 1 ergibt bei positiver und negativer Aufladung und einer Belichtungsintensität von ca. 3 µW/cm² (folgende Halbwertsenergien:

8. Auf eine mit Polycarbonat sehr dünn vorbeschichtete Al/PET-Folie werden die Pigmente

• 1. Hostapermorange GR (Formel E, trans-Perinon)
• 2. Hostapermscharlach GO (Formel G, CI 59300),
• 3. Perylen-3,4.9,10-tetracarbonsäurebisbenzimidazol (Formel D),
• 4. Novopermrot TG02 (Formel F, cis-Perinon),
• 5. N.N′-Di-n-butylperylimid (Formel B)
• 6. N.N′-Di-(3-methoxypropylperylimid (Formel C)

im Vakuum bei 1,3 × 10⁻⁷ - 10⁻⁸ bar und einer Temperatur von < 300 °C schonend aufgedampft. Die dabei erreichten Pigment-Schichtdicken liegen im Bereich von 100 - 160 mg/m².
Auf diese Schichten 1 - 4 wird eine Lösung aus 70 Gewichtsteilen Formel 5 und 30 Gewichtsteilen Vinylchlorid-Vinyl-Copolymerisat (Hostaflex M 131) geschichtet, auf die Pigmentschichten 4 - 6 kommt eine Transportschicht gleicher Zusammensetzung jedoch mit Polycarbonat als Bindemittel; die Dicke dieser Transportschichten liegt nach Trocknung bei ca. 10 µm.
Die Messung der Photoempfindlichkeit erfolgt analog Beispiel 1 (Belichtungsintensität 3,8 µW/cm²):

Von den PhL-Schichten Nr. 3 (Kurve 1) und Nr. 4 (Kurve 2) wurden außerdem die spektralen Photoempfindlichkeiten bei (-) 480 - 510 V Aufladung gemäß Beispiel 4 vermessen (Figur 7).
9. Auf eine Ladungserzeugungsschicht gemäß Beispiel 1 wird die THF-Lösung aus gleichen Gewichtsanteilen Polycarbonat und 1-(4-Chlorphenyl)-3(2-chlorstyryl)-5(2-chlorphenyl)-pyrazolin (Formel 7) in ca. 9 µm Dicke geschichtet. Desgleichen wird eine weitere Transportschicht aus 50 Gewichtsteilen Polycarbonat und 3 Gewichtsteilen 9-Bromanthracen auf die Pigmentschicht gebracht.
Bei einer Belichtungsintensität von ca. 3,7 µW/cm² wird die Photoempfindlichkeit vermessen:

1. An aluminum-vapor-coated polyester film (Al / PE T film) as an electrically conductive layer support is very thinly precoated with a solution of vinyl chloride-vinyl acetate copolymer (Hostaflex M 131 from Hoechst AG) (layer weight below 100 mg / m²) and then in a vacuum (1.33 × 10⁻⁷ - 10⁻⁸ bar) NN'-dimethylperylimide (formula table II, A) gently vaporized in the temperature range of approx. 290 ° C; the pigment layer thickness is about 140 mg / m². A tetrahydrofuran solution (THF solution) consisting of equal proportions of polycarbonate (Makrolon 3200 from Hoechst AG) and the following pyrazoline derivatives is placed on this charge generation layer:

• 1. 1,3-diphenyl-5 (2-chlorophenyl) pyrazoline (Formula 1 of Formula Table I)
• 2. 1,3-diphenyl-5 (4-chlorophenyl) pyrazoline (formula 3), and
• 3. 1,3-Diphenyl-5 (2,4-dichlorophenyl) pyrazoline (Formula 4) applied in 9-10 µ dry film thickness.
  For comparison, a layer with the charge transport connection is used in the same way
  2,5-bis (4-diethylaminophenyl) oxdiazole-1.3.4 (TO)
  produced.

The photosensitivity of these photoconductor double layers is measured as follows (halogen UV lamp, exposure intensity approx. 3.5 µW / cm²):
To determine the bright discharge curves, the test sample is moved through a charging device to the exposure station, where it is continuously exposed to a halogen W lamp (150 W). A heat absorption glass and a neutral filter are installed upstream of the lamp. The light intensity in the measuring plane is mainly in the range of 3 - 10 µW / cm²; it is measured in parallel with the measuring process with an optometer. The charge level and the photo-induced light decay curve are recorded by an electrometer using a transparent probe. The photoconductor layer is characterized by the charge level (U _o ) and the time (t) required to reach half, a quarter and an eighth of the original charge (U _o ). The product of the respective t [s] and the parallel measured light intensity [µW / cm²] leads to the characteristic amounts of energy [µJ / cm²] such as the half-value energy E _1/2 . The amounts of energy at which 1/8 of the initial charge (U _o ) is reached serve to characterize the residual discharge behavior of a photoconductor layer. The residual charge U _E , measured primarily after 1 or 3 s, is also a measure of the residual discharge behavior.

2. N, N'-dimethylperylimide (formula A) is evaporated onto an Al / PET film precoated with polycarbonate as in Example 1.
THF solutions made of equal parts by weight of polyester resin (Dynapol L 206 from Hoechst AG) and

• 1. 1,3-diphenyl-5 (2-bromophenyl) pyrazoline (Formula 1)
• 2. 1,3-diphenyl-5 (2-fluorophenyl) pyrazoline (formula 1)
• 3. 1,3-diphenyl-5 (2-chlorophenyl) pyrazoline (Formula 1)
• 4. 1,3-diphenyl-5 (3-chlorophenyl) pyrazoline (Formula 2)
• 5. 1,3-diphenyl-5 (4-chlorophenyl) pyrazoline (Formula 3)

applied in a thickness of about 10 µm after drying.
The photosensitivity is measured according to Example 1 (Hal / W. Lamp, exposure intensity 3.5-3.8 µW / cm²):

3. On a charge generation layer as described in Example 2, THF solutions are made of equal parts of polycarbonate and

• 1. 1-phenyl-3 (2-chlorostyryl) -5 (2-chlorophenyl) pyrazoline (formula 5),
• 2. 1-phenyl- (2,4-dichlorostyryl) -5 (2,4-dichlorophenyl) pyrazoline (formula 6),
• 3. 1,5-diphenyl-3-styryl-pyrazoline,
• 4. 1-phenyl-3 (4-methylstyryl) -5 (4-tolyl) pyrazoline as well
• 5. 1,5-Diphenyl-3 (4-methoxyphenyl) pyrazoline

layered and then dried at 90 - 100 ° C in a circulating air dryer.
Likewise, further transport layers of 50 parts by weight of charge transport compound formulas 1-5, 47 parts by weight of polycarbonate and 3 parts by weight of 9-bromoanthracene (MBA) are each applied to the pigment layer.
The approx. 10 µm thick photoconductor double layers are measured as in Example 1 (exposure intensity 4.3 - 5.0 µW / cm²): Phl layer Acceptor additive (-) U _o / V E _1/2 E _1/8 (-) U _E / V (after 3 s) 1 - 500 1.02 2.85 19th 2nd - 520 1.07 2.93 15 3rd - 490 1.19 3.6 27th 4th - 500 1.44 4.22 19th 5 - 485 1.65 6.15 35 1' MBA 530 0.82 2.15 11 2 ' MBA 505 0.85 2.23 15 3 ' MBA 480 1.08 2.91 23 4 ' MBA 485 1.3 3.83 23 5 ' MBA 480 1.26 3.54 17th The photoconductor layers with the charge transport connections 3, 4 and 5 are used for comparison purposes.
4. N, N'-dimethylperylimide (formula A) is continuously evaporated in vacuo onto a conductive layer support precoated with polycarbonate, so that the pigment layer thickness is approximately 130 mg / cm². Solutions of the following charge transport layers are applied:

• a) 50 parts by weight of Formula 5, 47 parts by weight of polycarbonate (Makrolon 3200) and 3 parts by weight of MBA and
• b) 50 parts by weight of formula 5, 47 parts by weight of vinyl chloride-vinyl acetate copolymer (Hostaflex M 131) and 3 parts by weight of MBA.

The following photosensitivity is measured according to Example 1 (Hal. W. lamp; exposure intensity ∼3.5 µW / cm²):

In addition, in the measuring arrangement described, the cyclic behavior (cyclic behavior) can be determined by measuring the 1st and 5th, if necessary, further light discharges.
The pre-exposure sensitivity (pre-exposure recommendation) is determined by measuring the light discharge at the beginning, exposure of the photoconductor layer under a fluorescent tube with approx. 10⁴ lx for 1 minute, which is followed by an equally long storage time in the dark and then the subsequent light discharge measurement.
The change in the electrophotographic data of these photoconductor layers under the specified conditions is very small according to the table.
The spectral photosensitivity of the double layer produced is determined using filters upstream using the method given in Example 1: In the case of negative charging (500-550 V), the half-life (t _1/2 in msec) for the respective wavelength range is determined by exposure. The spectral photosensitivity curve is obtained by plotting the reciprocal half-value energy 1 / E _1/2 (cm² / µJ) against the wavelength λ (nm). The half-value energy E _1/2 (µJ / cm²) means the light energy that has to be irradiated in order to discharge the layer to half the initial voltage U _o .
The spectral photosensitivity of the double layer a) can be seen in FIG. 5, charging (-) 490 - 520 V.
5. A charge-generating layer according to Example 1 is made with a THF solution consisting of 40 parts by weight of polycarbonate and 60 parts by weight of photoconductor compound

• A) 1,3-diphenyl-5 (2-chlorophenyl) pyrazoline (Formula 1)

coated in a thickness of 10 µm after drying.
In addition, transport layers of the composition 60 parts by weight of photoconductor compound, 37 parts by weight of polycarbonate (Makrolon 3200) and 3 parts by weight of electron acceptor compound are applied to the pigment layer in a thickness of approximately 10 μm. The halogenated anthracene derivatives were accepted

• 1.9-bromoanthracene (MBA)
• 2. 9-10-Dibromoanthracene (DBA) as well
• 3. 9-10-dichloroanthracene (DCA) used.

The results of the photosensitivity measurement are summarized in the following table (exposure intensity 3.8 - 4.7 µW / cm²):

In the case of layer A (formula 1), the residual discharge behavior can be improved in particular by means of acceptor additives.
6. A pigment preparation Hacolor # 50915 (from Hagedorn, Osnabrück) consisting of 70 parts by weight of ε-Cu-phthalocyanine (CI 74160: 6) and 30 parts by weight of cellulose nitrate is placed on an aluminum-vaporized polyester film (Al / PET film) in 310 mg / m² thickness coated. A solution of 70 parts by weight of styrylpyrazoline derivative (formula 5), 37 parts by weight of polycarbonate and 3 parts by weight of MBA in 11 and 14 μm thickness is applied.
The photosensitivity is determined in accordance with Example 1 and the spectral photosensitivity of the thinner coating is recorded in FIG. 6 with a charge of approximately (-) 180 V.

7. To a solution containing 40 parts by weight of Formula 5, 50 parts by weight of copolymer of styrene and maleic anhydride (Scripset 550 from Hoechst AG), 5 parts by weight of 9-bromoanthracene in tetrahydrofuran, 5 parts by weight of N, N'-dimethylperylimide (Formula A) are added and in one Ball mill grind very finely for 2.5 hours. The pigment dispersion is then layered on a surface-brushed aluminum foil in a thickness of approx. 5 µm.
In the same way, monodisperse layers are made from 45 parts by weight of the compound Formula 5, 50 parts by weight of Scripset 550 and 5 parts by weight of pigment of the following type

• 2. Hostapermorange GR (formula E, trans-perinone)
• 3. Hostapermscharlach GO (Formula G, CI 59300) as well
• 4. Benzothioxanthene-3,4-dicarboximide- (N, N'-mononitrophenylene-1,2) -imidine- (3) (Formula H, V 525M)

produced.
The measurement of the photosensitivity according to Example 1 gives positive and negative charging and an exposure intensity of approx. 3 µW / cm² (following half-value energies:

8. The pigments are applied to an Al / PET film which is very thinly coated with polycarbonate

• 1. Hostapermorange GR (formula E, trans-perinone)
• 2. Hostapermscharlach GO (Formula G, CI 59300),
• 3. perylene-3,4,9,10-tetracarboxylic acid bisbenzimidazole (formula D),
• 4. Novopermrot TG02 (formula F, cis-perinone),
• 5. NN'-di-n-butylperylimide (formula B)
• 6. NN′-di- (3-methoxypropylperylimide (formula C)

gently evaporated in a vacuum at 1.3 × 10⁻⁷ - 10⁻⁸ bar and a temperature of <300 ° C. The pigment layer thicknesses achieved are in the range of 100-160 mg / m².
A layer of 70 parts by weight of formula 5 and 30 parts by weight of vinyl chloride-vinyl copolymer (Hostaflex M 131) is layered on these layers 1-4, and a transport layer of the same composition but with polycarbonate as a binder is applied to the pigment layers 4-6. the thickness of these transport layers after drying is approx. 10 µm.
The photosensitivity is measured analogously to Example 1 (exposure intensity 3.8 µW / cm²):

From the PhL layers No. 3 (curve 1) and No. 4 (curve 2) the spectral photosensitivities with (-) 480 - 510 V charging were also measured according to Example 4 (FIG. 7).
9. On a charge generation layer according to Example 1, the THF solution is made from equal parts by weight of polycarbonate and 1- (4-chlorophenyl) -3 (2-chlorostyryl) -5 (2-chlorophenyl) pyrazoline (formula 7) in about 9 microns Layered thickness. Likewise, a further transport layer composed of 50 parts by weight of polycarbonate and 3 parts by weight of 9-bromoanthracene is applied to the pigment layer.
The photosensitivity is measured at an exposure intensity of approx. 3.7 µW / cm²:

Claims (13)

1. An electrophotographic recording material comprising an electrically conducting layer support, optionally an adhesion-promoting insulating intermediate layer and at least one binder-containing photoconductive layer which contains a charge-carrier generating compound and a pyrazoline derivative as charge-transporting compound, wherein the charge-transporting compound conforms to the formula I

   

   in which
   n denotes zero or 1 and
   R₁, R₂, R₃, R₄, R₅ denote hydrogen or halogen, with at least one of these substituents being halogen.
2. A recording material as claimed in claim 1, wherein the charge-transporting compound conforms to the formula I and
   R₁, R₂, R₃, R₄, R₅ denote hydrogen, chlorine or bromine.
3. A recording material as claimed in claim 2, wherein the charge-transporting compound is
   1-phenyl-3-(2-chlorostyryl)-5-(2-chlorophenyl)-pyrazoline
   or 1-phenyl-3-(2,4-dichlorostyryl)-5-(2,4-dichlorophenyl)-pyrazoline.
4. A recording material as claimed in claim 1 or 2 wherein the charge-transporting compound is
   1,3-diphenyl-5-(2-chlorophenyl)pyrazoline
   or 1,3-diphenyl-5-(2,4-dichlorophenyl)pyrazoline.
5. A recording material as claimed in claim 1, wherein the photoconductive layer comprises a charge-generating and a charge-transporting layer.
6. A recording material as claimed in claim 1, wherein the photoconductive layer contains polyester resins, vinyl chloride/vinyl acetate copolymers, polycarbonates or mixtures thereof as binder.
7. A recording material as claimed in claim 1, wherein the photoconductive layer contains an alkaline-decoatable binder.
8. A recording material as claimed in claim 7, wherein the photoconductive layer contains styrene/maleic acid anhydride copolymers, sulfonylurethanes, phenolic resins or copolymers of vinyl acetate with an unsaturated carboxylic acid as binder.
9. A recording material as claimed in claim 1, wherein the photoconductive layer contains a charge-carrier generating pigment.
10. A recording material as claimed in claim 9, wherein condensation products of perylene-3,4,9,10-tetracarboxylic acid dianhydride with alkylamines, arylamines, aralkylamines or o-aryldiamines are present as pigment.
11. A recording material as claimed in claim 9, wherein metal-containing or metal-free phthalocyanine is present as pigment.
12. A recording material as claimed in claim 1, wherein the photoconductive layer contains electron-acceptor compounds.
13. A recording material as claimed in claim 12, wherein anthracene or acridine derivatives halogenated in the 9 or 10-position are present as electron-acceptor compound.

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