DE3943468C2 - Electrophotographic photoconductor contg. new aldehyde hydrazone cpd. - Google Patents

Abstract

Electrophotographic recording material comprises a carrier sheet coated on one side with a photoconducting film contg. one or more hydrazone cpds. of formula (I) as charge transporting agent, mixed with or adjacent to a layer contg. a charge generator. In (I), R5-R8 are each opt. substd. alkyl, alkenyl, aryl or aralkyl; R9 is H, halogen, OH, alkoxy, NO2 or opt. substd. alkyl or aryl; and n is 0 or 1.

Description

The present invention relates to electrophotographic recording materials with a substrate and a photoconductive Layer on the substrate which is a new one Hydrazone compound in its photoconductive layer contain.

Photoconductive materials previously used in electrophotographic Recording materials used include inorganic photoconductive substances such as selenium and selenium alloys, dispersions inorganic photoconductive substances such as zinc oxide and cadmium sulfide in resin binders, organic photoconductive polymer substances, such as Poly-N-vinylcarbazole and polyvinylanthracene, organic photoconductive substances, such as Phthalocyanine compounds and bisazo compounds, and Dispersions of such organic photoconductive Polymer substances in resin binders.

Electrophotographic recording materials need an electrical surface charge maintained in the dark, an electric Generate charge upon receipt of light and an electrical one Transport cargo when light is received. The recording materials are divided into two types, in Recording materials of the so-called single-layer type and in Recording materials of the so-called laminate type. The former comprises a single layer with all of the above mentioned three functions, and the latter includes laminated layers in their functions are distinguishable, one mainly for Contributes to the generation of electrical charge and a  others to maintain electrical Surface cargo in the dark and transportation contributes to the electrical charge when light is received. In an electrophotographic process under Use of a recording material of the above Art becomes, for example, the Carlsonian system Image formation applied. The image formation according to this System involves exposing a recording material to the Darkness of a corona discharge to it loading, irradiating the surface of the loaded Imaging light recording material based on a Manuscript or copy carrier, d. H. Letters and / or Images, to form a latent electrostatic Image, the development of the formed latent electrostatic image with a toner and the Transfer the developed toner image to a Carrier, such as a paper web, for fixing the Toner image on the carrier. After the transfer of the Toner image becomes the recording material of removal of the electrical charge, a removal of the remaining Toner (cleaning), and neutralization of the residual charge with light (extinguishing), for reuse exposed.

Electrophotographic recording materials, wherein an organic photoconductive material is used recently used due to the beneficial Properties of organic materials, such as Flexibility, thermal stability and / or Film formation capacity. You close a photoconductor, comprising poly-N-vinylcarbazole and 2,4,7-trinitrofluoren-9-one (disclosed in U.S. Patent 3,484,237), a photoconductor using a organic pigment as the main component (disclosed in JP-OS 37 543/1972) and a photoconductor  Use as the main component, a eutectic Complex, composed of a dye and a resin (disclosed in JP-OS 10 785/1972). A variety of new hydrazone compounds have been developed also used for photoconductors.

DE 30 19 909 A1 describes hydrazone compounds which are used as charge transfer materials in photoconductors can be used. Among those in claim 1 of this General formula (I) specified in the publication falls

• a) the connection E1 (7)
• b) the connection E1 (14), which is a hydrazone compound substituted on the α-C atom.

In U.S. Patent 4,385,106 hydrazone compounds are disclosed in US Pat general formula E2 (I) described

in which a nitrogen atom of the hydrazone grouping a Paramethoxyphenyl group carries. Furthermore, the α-C atom with a p-dimethylaminostyryl or an o-methoxystyryl group be substituted.  

Although organic materials are a variety of advantages mentioned above with which inorganic There are materials that are not provided however no organic materials, all required properties of a material Use in electrophotographic recording materials exhibit. Particular problems with organic Materials occur that affect Photosensitivity and properties continuous repeated use.

The object of the present invention is a electrophotographic recording material for use in copiers and printers which has a high sensitivity to light and excellent properties with repeated use having.

According to a first embodiment of the invention includes a electrophotographic recording material Layer support and a photoconductive layer on the Layer support, characterized in that the photoconductive Layer at least one hydrazone compound of the following general Formula (II)

contains as a charge-transporting substance,
wherein each R₅, R₆, R₇ and R₈ denotes an alkyl group, an alkenyl group, an aryl group, an aralkyl group, which can each have at least one substituent,
R₉ represents a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, a nitro group or an alkyl group or aryl group, both of which can have at least one substituent, and
n represents an integer of 0 or 1.

This photoconductive layer can be a dispersion a charge generating substance and a hydrazone compound of the general formula (II) in a binder resin contain.

The photoconductive layer can also consist of a Charge transport layer with a hydrazone compound of the general formula (II), and a charge-generating Layer.  

According to a second embodiment of the invention includes a electrophotographic recording material Layer support and a photoconductive layer on the Layer support, characterized in that the photoconductive Layer at least one hydrazone compound of the following general formula (III)

contains as a charge-transporting substance,
wherein R₁₀, R₁₁, R₁₂ and R₁₃ are an alkyl group, an alkenyl group, an aryl group, an aralkyl group, each of which may have at least one substituent, at least one of the substituents R₁₀, R₁₁, R₁₂ and R₁₃ is a thenyl group which may have at least one substituent means
R₉ represents a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, a nitro group or an alkyl group or aryl group, both of which can each have at least one substituent, and
n represents an integer of 0 or 1.

This photoconductive layer can be a dispersion a charge generating substance and a hydrazone compound of the general formula (III), in a binder resin contain.  

The photoconductive layer can also consist of a charge transport layer with a hydrazone compound of the general formula (III), and a charge-generating Layer.

Figs. 1 to 3 are schematic cross-sectional views of novel recording materials.

The recording material according to the invention, which contains a hydrazone compound in a photoconductive layer, can have one of the structures of FIGS. 1, 2 or 3, depending on the application of the hydrazone compound thereon.

Fig. 1 shows a one-layer type recording material. A photoconductive layer 2 A is provided on an electrically conductive substrate 1 . The photoconductive layer 2 A comprises a charge generating substance 3 and a hydrazone compound as a charge transporting substance 5, both of which substances are dispersed in a resin binder matrix so that the photosensitive layer acts as 2 A photoconductor.

Fig. 2 shows a laminate type recording material. A laminated photoconductive layer 2 B is provided on an electroconductive substrate 1, wherein the lower layer of the laminate is a charge generating layer 4, including a charge generating substance 3 as a main component, and the upper layer, a charge transporting layer 6 containing a hydrazone compound as a charge-transporting substance 5 , so that the photosensitive layer 2B acts as a photoconductor. This recording material is usually used in accordance with the negative charge mode.

Fig. 3 shows another laminate type recording material with an inverted layer structure to that of Fig. 2. A laminated photoconductive layer 2 C is provided on an electrically conductive substrate 1 , the lower layer of the laminate being a charge transporting layer 6 including a hydrazone compound as is a charge transport substance 5 , and the upper layer is a charge generation layer 4 including a charge generation substance 3 . This light-sensitive layer also acts as a photoconductor. This recording material is usually used in accordance with the positive charge mode. In this case, a cover layer 7 can also be provided, as shown in FIG. 3, in order to protect the charge-generating layer 4 .

There are thus two different types of layer structures in the recording material. The reason for this is that even if a recording material having the layer structure shown in Fig. 2 is used in the positive charge mode, no charge-transporting substances which can be adapted to the positive charge mode have so far been found. Therefore, when the positive charge mode is used, the recording material must have a layer structure as shown in Fig. 3.

A recording material according to the Fig. 1 can be prepared by dispersing a charge generating substance in a solution of a charge generating substance and a resin binder and applying the resulting dispersion are produced on an electrically conductive support.

A recording material according to Fig. 2, by depositing a charge generating substance on an electroconductive substrate by means of vacuum evaporation or applying and drying a dispersion of a particulate charge generating substance in a solvent and / or a resin binder on an electroconductive substrate, followed by applying a Solution of a charge transport substance and a resin binder on the obtained Schciht and drying.

A recording material according to FIG. 3, by applying and drying a solution of a charge transporting substance and a resin binder on an electroconductive substrate, and depositing a charge generating substance on the resulting layer by vacuum evaporation or coating and drying a dispersion of a particulate charge generating substance in a solvent and / or a resin binder on the layer, followed by the formation of a top layer.

The electrically conductive substrate 1 serves as the electrode of the recording material and as the substrate for the layers formed thereon. The electrically conductive support can be in the form of a cylinder, a plate or a film or a foil and can be made of a metallic material, such as aluminum, stainless steel or nickel, or another material whose surface has been treated to make it electrically conductive such as glass or resin.

The charge-generating layer 4 is formed by applying a dispersion of a particulate charge-generating substance 3 in a resin binder or by evaporating a charge-generating substance in vacuo or another technique described above, and this layer generates an electric charge upon receiving light. It is important that the charge generating layer 4 not only has a large charge generating effectiveness, but also has the ability to inject the generated electrical charge into the charge transporting layer 6 and each cover layer 7 , which ability desirably as little as possible from the electrical Field depends and is still high even with low intensity electric fields. Common charge generating substances include phthalocyanine compounds such as metal-free phthalocyanine and titanyl phthalocyanine; various azo, quinone and indigo pigments, dyes such as cyanine, squarylium, azulenium and pyrylium compounds; and selenium and selenium compounds. Among these, a suitable connection can be selected depending on the wavelength range of a light source used for the image formation. The thickness of the charge generating layer is determined depending on the extinction coefficient of a charge generating substance used therein with respect to the function of the electric charge generating layer, but is generally 5 µm or less, preferably 1 µm or less. It is also possible to use a charge generating layer using a charge generating substance as a main component in a mixture with a charge transporting substance. Resin binders suitable in the charge generating layer include polycarbonates, polyesters, polyamides, polyurethanes, epoxy resins, silicone resins and methacrylate homopolymers and copolymers, which can be used either alone or in an appropriate mixture ratio.

The charge transport layer 6 is a coating film containing a hydrazone compound as an organic charge transport substance in a resin binder. The charge transport layer serves as an insulator layer in the dark to maintain the electrical charge of the recording material and transports an electrical charge injected from the charge generating layer upon image reception. Resin binders suitable in the charge transport layer include polycarbonates, polyesters, polyamides, polyurethanes, epoxy resins, silicone resins and methacrylate homopolymers and copolymers.

The cover layer 7 has the function of receiving and maintaining an electric charge generated by corona discharge in the dark and the ability to transmit light to which the charge generating layer should respond. It is necessary that the top layer transmit light upon exposure of the recording material and cause the light to reach the charge generating layer and then the injection of an electric charge generated in the charge generating layer to neutralize and erase a surface electric charge. Materials that are suitable in the top layer include organic, insulating film-forming materials such as polyesters and polyamides. These organic materials can also be used in a mixture with an inorganic material, such as a glass resin or SiO₂, or a material for lowering the electrical resistance, such as a metal or a metallic oxide. Materials which are suitable in the cover layer are not limited to organic, insulating materials for film formation and further include inorganic materials such as SiO₂, metals and metallic oxides, which form a cover layer by a suitable method, such as vacuum evaporation and deposition or Atomization or spraying can be formed. In view of the above description, it is desirable that the material used in the cover layer be as transparent as possible in the wavelength range in which the charge generating substance reaches its maximum light absorption.

Although the thickness of the top layer of their material or its composition, it can be chosen arbitrarily, as long as no disadvantageous Effects, including an increase in Residual potential with continuous repeated Use, occur.  

The hydrazone compounds used according to the invention include two groups of compounds that each easily by a known method can be produced.

The first group of hydrazone compounds has the following general formula (II)

in which R₅, R₆, R₇ and R₈ represent an alkyl group, an alkenyl group, an aryl group or an aralkyl group, each of which may have at least one substituent,
R₉ represents a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group or an alkyl group or aryl group, both of which can have at least one substituent, and
n represents an integer of 0 or 1.

These connections are made through Dehydration condensation of an aldehyde compound of the formula

with a hydrazine compound of the formula

in a suitable organic solvent, such as Ethanol, in the presence of a small amount of one Catalyst, such as an acid.

Specific examples of hydrazone compounds of the general formula (II) based on the above can be produced, include the following one:

The second group of hydrazone compounds has the following general formula (III)

wherein R₉ as defined in the general formula (II) is each R₁₀, R₁₁, R₁₂ and R₁₃ an alkyl group, an alkenyl group, an aryl group or one Aralkyl group, each having at least one May have substituents, means and at least one of the substituents R₁₀, R₁₁, R₁₂ and R₁₃ one Thenyl group, which has at least one substituent can have means.  

The compounds of the general formula (III) can in the same way as the connections of the general formula (II) can be prepared.

Specific examples of hydrazone compounds of the general formula (III) based on the above can be produced, include the following one:

The following examples illustrate the invention.

example 1

50 parts by weight of metal-free phthalocyanine pulverized with a ball mill for 150 hours, and 100 parts by weight of the hydrazone compound No. II-1 mentioned above were mixed with 100 parts by weight of a polyester resin and tetrahydrofuran (THF) as a solvent with a mixer for 3 hours Production of a coating liquid kneaded. The coating liquid was applied to an aluminum-coated polyester film (Al-PET) as an electrically conductive substrate using wire rod technology to form a photoconductive layer with a dry thickness of 15 μm. In this way, a recording material having the structure shown in Fig. 1 was produced.

Example 2

The electrophotographic recording material of Example 2 was in essentially in the same way as in Example 1 made except that the connection No. III-1 instead of the hydrazone compound No. II-1 as used in Example 1.  

Example 3

Metal-free α-phthalocyanine as a starting material was in a fine powder with a Fine grinding device, wherein a non-magnetic can containing the metal-free α-phthalocyanine and Teflon pieces as small particles between two linear motors that facing each other, was ordered powdered. A sample from 1 part by weight of the so Fine powder produced was made in 50 parts by weight DMF (N, N-dimethylformamide) as a solvent an ultrasonic dispersion treatment. The sample of DMF was then filtered separated and dried to treat the complete metal-free phthalocyanine.

A solution of 100 parts by weight of the hydrazone compound No. II-2 mentioned above in 700 parts by weight of tetrahydrofuran (THF) was mixed with a solution of 100 parts by weight of polymethyl methacrylate (PMMA) in 700 parts by weight of toluene to prepare a coating liquid. The coating liquid was applied to an aluminum-coated polyester film layer support by means of the wire rod technique to form a charge-transporting layer with a dry thickness of 15 μm. 50 parts by weight of the metal-free phthalocyanine treated in the above manner and 50 parts by weight of a polyester resin were kneaded with a mixer for 3 hours together with THF as a solvent to prepare a coating liquid, which was then applied to the charge transport layer by the wire rod technique for formation a charge-generating layer with a dry thickness of 1 µm was applied. In this way, a recording material having the structure shown in Fig. 3 was produced. A cover layer, which is not mandatory according to the invention, was not provided.

Example 4

The electrophotographic recording material of Example 4 was in essentially in the same way as in Example 3 made except that the connection No. III-2 instead of the hydrazone compound No. II-2 as used in Example 3.

Example 5

An electrophotographic recording material was prepared by forming one photoconductive layer on essentially the made in the same way as in Example 1 with the Exception that 50 parts by weight of metal-free phthalocyanine, 100 parts by weight of hydrazone compound No. II-3, 50 parts by weight of a polyester resin and 50 Parts by weight of PMMA instead of the composition of the photoconductive layer of Example 1 used were.

Example 6

The electrophotographic recording material of Example 6 was im essentially the same way as in Example 5 made except that the connection No. III-3 instead of the hydrazone compound No. II-3 as used in Example 5.  

Example 7

An electrophotographic recording material was prepared by forming one photosensitive layer on essentially the prepared in the same way as in Example 3, with the Except that chlordian blue instead of the metal-free phthalocyanine in Example 3 was used.

Example 8

The electrophotographic recording material of Example 8 was im essentially the same way as in Example 7 made except that the connection No. III-2 instead of the hydrazone compound No. II-2 as used in Example 7.

The electrophotographic properties of the eight so prepared recording materials was using a electrostatic recording paper tester measured.

The surface potential V _s [V] of each recording material is an initial surface potential which was measured when the surface of the recording material was positively charged in the dark by corona discharge at +6.0 kV for 10 s. After the corona discharge was completed, the recording material was left standing in the dark for 2 seconds, after which the surface potential V _d [V] of the recording material was measured. Subsequently, the surface of the recording material was irradiated with white light having a light intensity of 2 lx, and the time [s] required to lower the surface potential of the recording material to half V _d was measured, from the time and the Illuminance the half-value exposure amount E _1/2 [lx · s] was calculated. The surface potential of the recording material after 10 s exposure to white light with an illuminance of 2 lx was measured as the residual potential V _r [V]. When a phthalocyanine compound was used as the charge generating substance, high sensitivity to light with longer wavelengths could be expected. Therefore, the electrophotographic properties thereof were also measured using monochromatic light with a wavelength of 780 nm. In particular, V _s and V _{d of} each recording material were measured in the same manner as described above, and the half-value exposure amount [µJ / cm²] was determined by irradiating the surface of the recording material with monochromatic light (wavelength: 780 nm) of 1 µW instead of white Light was determined while the residual potential V _r [V] was measured after irradiating the surface of the recording material with the aforementioned light for 10 s. The results of the measurement are shown in Table 1.

Table 1

As can be seen from Table 1, the Recording materials of Examples 1 to 8 in their Half-value exposure amounts and the residual potential not very different and showed good ones Surface potential properties. The recording materials of the Examples 1 to 6 using a Phthalocyanine compound as charge generating Substance, also showed excellent electrophotographic properties for light with a long wavelength of 780 nm.

Example 9

Selenium was deposited on an aluminum plate with a thickness of 500 µm by vacuum evaporation to form a charge generating layer with a thickness of 1.5 µm. A solution of 100 parts by weight of the hydrazone compound No. II-4 mentioned above in 700 parts by weight of tetrahydrofuran (THF) was mixed with a solution of 100 parts by weight of polymethyl methacrylate (PMMA) in 700 parts by weight. Parts of toluene were mixed to prepare a coating solution, which was then applied to the charge generating layer by the wire rod technique to form a charge transporting layer with a dry thickness of 20 µm. In this way, a recording material having the structure shown in Fig. 2 was produced. This recording material was charged by corona discharge at -6.0 kV for 0.2 s and examined for its electrophotographic properties, with good results being shown, namely V _s = -620 V, V _r = -40 V and E _1/2 = 5.3 lxs.

Example 10

The electrophotographic recording material of Example 10 was prepared in substantially the same manner as in Example 9, except that the compound No. III-4 was used instead of the hydrazone compound No. II-4 as in Example 9. When the electrophotographic properties of this sample were measured in the same manner as in Example 9, good results were obtained, namely V _s = -600 V, V _r = -50 V and E _1/2 = 4.9 lx · s.

Example 11

50 parts by weight of the same as in Example 3 treated metal-free phthalocyanine, 50 Parts by weight of a polyester resin and 50 Parts by weight of PMMA were used together with THF Solvent with a mixer for 3 h Making a coating solution kneaded the then on an aluminum support to form a charge-generating layer with a thickness of about 1 micron was applied. Then 100 Parts by weight of hydrazone compound No. II-5, the mentioned above, 100 parts by weight of one Polycarbonate resin and 0.1 part by weight of a Silicone oil with 700 parts by weight of THF and 700 parts by weight Toluene to make a coating solution mixed, which then on the charge generating layer to form a charge transport layer a thickness of about 15 microns was applied.  

The recording material thus produced was charged by corona discharge at -6.0 kV for 0.2 s and examined for electrophotographic properties in the same manner as in Example 9, whereby good results were obtained, namely V _s = -620 V and E _{1 / 2} = 5.1 lxs.

Example 12

The electrophotographic recording material of Example 12 was prepared in substantially the same manner as in Example 11, except that Compound No. III-5 was used in place of Hydrazone Compound No. II-5 as in Example 11. When the electrophotographic properties of this recording material were measured in the same manner as in Example 9, good results were obtained, namely V _s = -650 V, E _1/2 = 6.4 lx · s.

Example 13

Electrophotographic recording materials were prepared in substantially the same manner as in Example 7, except that the hydrazone compounds Nos. II-6 to II-12 and Nos. III-6 to III-24 were used instead of the compound No. II-2, respectively were. The results obtained using the electrostatic recording paper tester are shown in Table 2. Table 2 shows the half-value exposure amounts e _1/2 [lx · s] which are obtained under experimental conditions, in which the recording materials are positively charged in the dark by corona discharge at +6.0 kV for 10 s and with white light at an illuminance of 2 lx were irradiated.

Table 2

It can be seen from Table 2 that the recording materials using the corresponding hydrazone compounds Nos. II-6 to II-12 and Nos. III-6 to III-24 were satisfactory in terms of the half-value exposure amount E _1/2 .

Since a hydrazone compound according to the invention is shown by one of the chemical formulas mentioned above, in a photoconductive layer, formed on a electrically conductive layer support, as charge transport substance is used shows an electrophotographic recording material has a high sensitivity and excellent properties with repeated use, if it is either in a positive charge mode or a negative charge mood is adjusted. A Suitable charge-generating substance can be chosen that they depend on the type of exposure source is adjusted. For example, a Phthalocyanine compound or a bisazo compound as Charge generating substance used to make an electrophotographic To result in recording material used in semiconductor laser printers can be used. If necessary, one Cover layer on the surface of an electrophotographic recording material be provided to improve their durability.

Claims (6)

1. Electrophotographic recording material with a support and a photoconductive layer on the support, characterized in that the photoconductive layer has at least one hydrazone compound of the following general formula (II) contains as a charge-transporting substance, wherein each R₅, R₆, R₇ and R₈ denotes an alkyl group, an alkenyl group, an aryl group, an aralkyl group, each of which may have at least one substituent, R₉ denotes a hydrogen atom, a halogen atom, a hydroxyl group, an alkoxy group, one Nitro group or an alkyl or aryl group, both of which may each have at least one substituent, and n is an integer of 0 or 1. 2. Recording material according to claim 1, characterized in that that the photoconductive layer is a dispersion a charge generating substance and a hydrazone compound of the general formula (II) in a binder resin contains. 3. Recording material according to claim 1, characterized in that that the photoconductive layer from a charge transport layer with a hydrazone compound of the general formula (II), and a charge-generating Layer is built up. 4. Electrophotographic recording material with a support and a photoconductive layer on the support, characterized in that the photoconductive layer has at least one hydrazone compound of the following general formula (III) contains as a charge-transporting substance, wherein R₁₀, R₁₁, R₁₂ and R₁₃ are an alkyl group, an alkenyl group, an aryl group, an aralkyl group, which may each have at least one substituent, at least one of the substituents R₁₀, R₁₁, R₁₂ and R₁₃ is a thenyl group which may have at least one substituent, R₉ means a hydrogen atom, a halogen atom, a hydroxy group, an alkoxy group, a nitro group or an alkyl or aryl group, both of which may have at least one substituent, and n is an integer of 0 or 1. 5. Recording material according to claim 4, characterized in that the photoconductive layer is a dispersion a charge generating substance and a hydrazone compound of the general formula (III), in a binder resin contains. 6. Recording material according to claim 4, characterized in that the photoconductive layer from a charge transport layer with a hydrazone compound of the general formula (III) and a charge-generating Layer is built up.