SU540581A3 - Electrophotographic element - Google Patents

Description

(54) ELECTROPHOTOGRAPHIC ELEMENT

These are not able to hold the electrostatic charge, and to a high rate of discharge. In addition, when using photoradiating layers, it is necessary that the photoconductor constitutes either one hundred percent of the whole layer (with vitreous selenium) or most of the photoconductive material in the layer based on the binder.

However, the need for the photoconductive layer to consist entirely or mainly of photoconductive material limits the physical characteristics of the element, drum or tape, such as i-ibrability and photoconductor adhesion to the substrate, since these physical properties are mainly determined by the physical properties photoconductor, not resin or matrix material (the content of the latter should be limited).

The purpose of the invention is to manufacture an electrophotographic htement with relatively small amounts of photosensitive material and with increased wear resistance chemical resistance and fatigue resistance to light, as well as an effective injection of photogenerated charge from a photosensitive element.

This is achieved by making an electrophotographic element containing an active transporting material that is capable of supporting injection and transport of photogenerating a single charge, and a pigment that has a high efficiency for photo-generating charge carriers and the ability to effectively inject itx into the transporting material.

In general, the pigment of the present invention has a maximum photosensitivity to curing with a wavelength region for which most active transporting materials are not absorbing materials.

Pigments are capable of injecting photoexcited electrons or dfoc into an active transporting material with extremely high efficiency.

An active transporting material can be a material capable of supporting the injection of holes or electrons, provided it has transparency and is unable to absorb radiation in the wavelength region to which the photoconductor is photosensitive.

Actual transporting material is not a photoconductor in the used wavelength region.

The electron-pair pairs are generated in the photosensitive pigment, and the electrons are then injected through the field-modulated barrier into the active transporting material, where the transport of electrons through the active transporting material takes place.

The achievement of the utmost goal of usable hinakridonovge nyu men in combination with austere

transporting electrons or holes by mothers.

Most linear linear trans-quinacridones of formula I

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which may have the necessary substitutes. A representative of this class is linear trans-quinacridone, known in the three crystalline phases o and y.

Optimal results are shattered with the use of - and 7-crystalline forms of trans-hinakri: i, OHOB.

Suitable cnnacridones can be obtained by known methods AND j, 2

As D-and y-crystalline forms of unsubstituted methyl-, methoxy- and chlorine-substituted trans-quinacridones, for example, 3-methyl-, 2-chloro, 4-chloro, 2,9-dimethle, 2.9 -dkmetoksKK-, 2,9-dichloro-, 3,10-dimetal-, 4,1 i-dimethyl-, 3,10-dichloro-, 2,3-dichloro-, 4,11-dichloro-, 2-chloro -4-methyl- and 2,9-dichloro-4,11-dimethyl-trans-quinacridones. Other quinacridones may be used, including cis isomers, or mixtures thereof, for example, 2, O-dichloro-6,13-dihydroquinacridone, 2,9-dimethoxy-6, 13-dihydroquinacridone, 2,9-dimethyl-6,13- dihydroquinacridone, 4,11-dimetal-6,13-dihydroquinacridone, 3.4,10.11-tetra-11orhinacridon 1.4.8.11 h-tetrafluorochnnacridone, 2,4,9, P-tetramethylquinacridone, 2,8-dichloro-dinacridon, 1,2,4,8, 9, P-hexachloroquinacrndon, 2,4,9,11-tetramethoxyquinacridone and mixtures thereof.

In addition, other quinacridones 3 may be used.

Writable quinacridone pigments differ from other photosensitive materials known in this field in that they are effective against photogeneration and injection and, moreover, have excellent compatibility with the 6f 1 hole transporting holes or electrons of materials, resulting in an opportunity for relatively low fields. in xerographic photoreceptor elements to provide injection and a reduction factor.

Quinacridone pigments also have optical Malva photosensitivity and a maximum photoresponse in the wavelength range from 4500 to 6500 A, which is the area of xerographic use and 15 of which the APPROACH active transducer has a significant degree of transparency. Many well-known photoconductors that are sensitive to radiation with this region of wavelengths do not have sufficient compatibility with the active transport materials listed in dp and are not effective for the injection of photogenerated charges into the surrounding or adjacent active transporting material. Therefore, the use of these photoconductive materials in combination with active transport materials requires a practically unacceptable field of more than 5 X10 V / cm.

The proposed pigments are used with transporting materials in relatively small amounts in a xerographic photoreceptor of a binder or binder based structure.

In one embodiment of the invention, the electrophotographic element is an electrically conductive substrate comprising a photoconductor layer coated on top with an active transporting material.

For example, a photoconductor layer may consist of a / 3-crystalline form of a linear quinacridone coated with a relatively thick layer of electron-withdrawing material, such as 2,4,7-trinitro-9-fluorene, which is capable of supporting the injection and transport of electrons.

With such properties of the pigment and its compatibility with the active transporting material, it is possible to use relatively thin layers of the hyacridine pigment without any loss of its effectiveness.

1 shows an electrophotographic element (two variants); in fig. 2 - imaging using the proposed element.

Substrate 1 ii of an octophotographic element (or other carrier) may be from metal (for example, brass, aluminum, gold, platinum, steel) of any thickness, rigidity or flexibility in the form of a sheet, tape or cylinder and may be covered with a thin blocking layer. It may also consist of paper, metallized paper, plastic sheets coated with a thin layer of copper oxide or aluminum, or glass coated with a thin layer of chromium or tin oxide.

Preferably, the substrate is somewhat electrically conductive or has a conductive surface and is sufficiently strong. In some cases, the substrate 1 does not have to be conductive or may be completely absent.

The photoconductive single or .unitary layer 2 contains a quinacridone pigment, for example a linear trans-quinacridone. Quinacridone pigments are effective photogenerators and charge injectors.

Layer 2 (see fig.1a) can be any kind of toli. Layers 0.05–20.0 µm thick are used.

the particle size of the photoconductor is 0.2–5.0 μm, since in this case the photoconductor functions to the maximum extent with a minimum of its quantity.

FIG. 16 shows a layer consisting of pigment particles dispersed in a matrix material, which can be any organic substance, including inert matrix or bonding materials and active transporting materials.

The concentration of the photoconductive material varies depending on the type used from the zunitz and is maintained in the range of 5-99% with respect to the volume of the photoconductive layer.

If an inert binder is used in combination with a photo-injecting pigment, then at least 25% (by volume) of the photoconductor is needed to ensure the contact of the particles, counting as an inert binder. Preferably, the layers are 0.2-5.0 μm thick.

The proposed pigments have an optimal photosensitivity to radiation with a dpm range of 4500-6500 A. Therefore, exposing a bath to a light source emitting at this wavelength interval causes the pigment to function with maximum efficiency in terms of absorbing all the incident radiation and generating charge carriers.

The active transport layer 3 is applied on top of layer 2.

The active transporting material can transport electrons or holes 4, 6. As the material transporting holes, carbazole, N-ethylcarbazole, N-isopropylcarbazole, N-phenylcarbazole, tetraphenylpyrene, 1-methylpyrene, perylene, trisphene, anthracene, tetracene, tetrafen, 2-phenylnaphthalene, azopiren, fluorene ,. flabrenone, 1-ethylpyrene, acetylpyrene, 2,3-benzochrizene, FOR benzopyrene, 1,4-bromgshen, phenylindole, watering unylcarbazole, polyvinylillire, polyvinyl tetracene polyvinyl pyril and polyvinyl tetrafen.

Suitable electron transport materials include 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitrofluorenone, dinitro-zoanthracene, dinitroacridone, tetracyanopyrene, dinitroanthraquinone.

Polymers containing suitable aromatic or heterocyclic substituents may also be used, for example polyesters, poly (zloxanes, polyamides, polyurethanes and epoxy resins, block, graphite and random copolymers.

The most suitable active transporting layers with a thickness of 5-100 μm with a ratio of the thickness of the active transporting layer to the thickness of the photoconductor layer are 2: 1–200: 1.

Transparency of the active transporting material to radiation with a wavelength interval

4500 - 6500 A should be such that a sufficient amount of radiation from the source passes through the layer 3 so that the photoconductor and the second layer 2 can function to the maximum as a photogenerator and charge carrier injector.

The choice of active transporting materials that are transparent in the full visible area is not strictly limited. For example, when a layered structure (see figs) with a transparent substrate is used that carries image information, exposure can be performed through the substrate without passing light through the layer of active transport material.

In this case, it is not required that the active material be non-absorbent in the used wavelength region.

This is due to the injection properties of the photoinjecting pigment described.

Other areas of use that do not require full transparency from the active material include selective recording of narrow-band radiation, such as emitted by lasers, recognition of spectral patterns, color code duplication, and possibly color xerography.

Layer 3 (see Fig. 1) may also contain a charge transporting material dispersed in sufficient concentration in a suitable inert binder to ensure the contact of the particles, thereby effectively transporting the charge from the pigments through the layer.

To ensure the necessary contact of the particles with each other or to bring them closer together, the amount of active transporting material relative to the inert one should be at least 25% (by volume).

Typical polymeric binder materials are, for example, polystyrene, silicone resins DS-801, DS-804, DS-99bGus manufactured by Dow Corning Corporation; polycarbonate, such as Lexan and SR 82, manufactured by General Electric, acrylic and methacrylic polymers, such as acryloid A 10 and acryloid B 72, polymerized derivatives of acrylic ioc-acrylic acid esters of Room and Haas Company; lucite 44, lucite46; polymerized butylmethacrylates from DuPont de Nomurs and chlorinated rubber, for example, Hercules Powder firm material; vinyl polymers and copolymers, for example polyvinyl chloride, polyvinyl acetate, cellulose esters and ethers; alkyd resins, for example glyptal 2469 from General Electric Company, in particular cellulose cellulose or nitrocellulose.

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In addition, mixtures of such resins can be used with each other or with a plasticizer for

improve adhesion, durability and formemort coatings.

Dp of the best combination of physical and reflective properties The upper limit for the concentration of the photoconductive pigment is 5 vol.% Of the active transport sludge on the basis of the binder.

The lower limit for the concentration of photoconductive particles should be 0.1 vol.% For

that the light absorption coefficient is sufficient to produce noticeable carrier generation.

Good results are obtained with a layer thickness based on a binder of 5-50 microns and sizes

choatac in the range of 0.01-1.0 microns.

Although the layered structure (see FIG. 1a) is different from the photoreceptor based on the binder (see Fig. 1b), the functional relationship between the photosensitive material and the active transporting material is the same in both cases. meaning that photogeneration of charges occurs in the photosensitive particles and subsequent injection into the surrounding active transporting material. Therefore, any description of the layered structure (see Fig. La) regarding the nature of the materials and their interactions is applicable in this case, except that due to the proximity of the photosensitive particles to the photoreceptor surface, the binder-based plate is preferably charged with the same charge. polarities, such as photogenerated charges that can be transported by an active Transporter material. Therefore, if an electron transporting material is used as a binder, the plate is mainly negatively charged, while a positive charge is preferable when using a transporting hole of the material.

When using other structure options,

depicted in FIG. 1a, 6b, it is necessary to use a blocking layer at the interface between the substrate and the photocell. Such a blocking layer serves primarily to reduce the potential leakage in the absence of activating radiation. The blocking layer also helps to maintain the electric field in the photoreceptor after the charging step,

Mo; rt be used blocking layer thickness of 0.1 - 1 micron. Typical materials

for the blocking layer, nylon, epoxy resin, alumina, and insulating resins, including polystyrene, butadiene polymers and copolymers, acrylic and methacrylic polymers, vinyl resins, alkyd resins, and resins on resins

based on cellulose.

The resistivity of the active transporting material must be at least ohm cm (exceeding; d11, almost equal to 1).

In order to obtain optimal results, it is preferable that the resistivity should be considered by the participants, who should complete the h;

In Figure 2, where | janicKipOHbi ayungs cipyKiypa | ria? Ypar is positively positive; with a corona discharge, the activating radiation (shown by checkboxes A) penetrates through the transparent active transfer layer into the pygmy pair.

Electric) it and the hole are then separated by an applied field and the electron is injected through the interface into the active transporting layer, in which the electron is transported by electrostatic attraction through the active transporting system to the surface, where it neutralizes the positive charge previously applied corona discharge. Since only photogenerated electrons can move in such a layer, large changes in the magnitude of the surface potential can occur only when the electric field in the layered structure is able to move the photogenerated electrons from the photoconductor layer to the charged surface. Therefore, it is necessary that in the layered structure shown in FIG. 1a, the photoblock from the electron transporting material was positively charged, and the photoreceptor from the transporting hole of the material was negative.

If the system is a binder based layer, shown in FIG. 16, the picture is the opposite.

Example 1. A plate or a layered structure similar to that shown in FIG. 1, is made as follows.

on a layer covered with a NYLON layer (thickness 0.2 μm) ... g; a substrate substrate at room temperature vacuum layer evaporation (0.8 μm) is applied to a Monastral Violet R (crystalline form of the Dupont le Nomurs inner quinacridon). Then, a 17% polymer solution is prepared by dissolving the appropriate colloid of poly-N-vinylcarbazole (PVC; variety Luvi an MI70 from BASF Kzmikal Corp.) in a mixture of 200 g of toluene and 20 g of cyclohexanone.

A layer of PVC with a thickness of 7 µm is formed by depositing a solution of PVC with a layer of pigment and pumping out the photoreceptor with air at 110 ° C for 2-24 hours.

PRI mme R 2. In analogy to Example 1, another plate was made using .Monastral Red B (7-crystalline form of Dupont de Nomurs Co quinacridon) as a pigment.

This plate (as well as the plate from Example 1) is tested electrolytically as follows. Samples are charged with a negative

of a corona charge up to Poki nial 500V, Zareem is exposed to monochromatic light with internally high wavelengths, in which the pigment is sensitive. Since the described pigmesh have

n the maximum photosensitivity in the visible region of the electromagnetic spectrum (4500-6500 A), then I expose the photoreceptors with a tungsten lamp using an interfer 1. ion filter with a bandwidth of 100 A, having a maximum

5 transmission at 5200 A.

Additional measurements are carried out with other filters whose transmission peaks are located throughout the region in the range from 4500 to 6500 A. The initial voltage and the resulting discharge, measured as (dV / dT) .j. at every

individual experiment, is solved with a DC loop probe, which is connected to an electrometer for measuring stresses as a function of time, which leads to

5 photo response graphics in the function of the floor.

From the experimental data, the maximum gain factor (s) and the threshold field E (the field that gives the smallest regurgible discharge) is obtained.

0In addition, from the magnitude of the initial velocity

discharge can calculate the value of the gain (G).

Experimental technique and calculation methods. described in P. Regensburger Optical

media sensitization in Photochemistry and Photobiology, 8, p. 4 9-440,1968.

The gain factor is determined by plotting the initial xerographic gain curve as a function of the applied field.

A xerographic gain of one

observed upon excitation of a single charge carrier to the feed photon and moving through the layer.

All pigments require a relatively low threshold floor (about 12 V / µm), which indicates that the pigments according to the proposed invention are capable of operating under working conditions in most xerographic machines.

In addition, high discharge rates confirm the efficiency of injecting photogenerated charges with quinacridone pigments.

The table shows the maximum xergraphic gain factor of two plates. Lines can be used with jJieKipoHbi transporting materials. In experiments with an electron transporting photoreceptor, HDHepxHocib is positively charged and measurements are carried out as in Examples 1 and 2. The xerographic properties of photoreceptors, which transport electrons, are similar to those of hole transporting materials shown in the table, i.e. they have acceptable xero graphic gains and relatively low threshold fields. Formula of the invention 1. An electrophotographic element having a photoreceptor element containing a charge-generating photosensitive material and an active charge transporting material that supports the effective injection of photogenerated charges from a photosensitive material, characterized in that in order to provide enhanced wear resistance, chemical resistance, resistance to light absorption, as well as an effective injection of photogenerated charges from a photosensitive element, as a generating The charges of the photosensitive material used hpnacridone pigment and the active transporting material is a material that does not absorb radiation with a wavelength range of 4500-6500 A. 2. The electrophotographic element according to PL, characterized in that it uses a photoreceptor element containing a quinacridone pigment dispersed in active binder transporting material. 3. An electrophotographic element according to claim 1, characterized in that it utilizes a photoreceptor element of a layered structure, containing a single layer of quinacridon pigment with a thickness of 0.05-20.0 µm and located on the top of the active transport material with a thickness of 5-100 µm. 4. The electrophotographic element of claim 3, characterized in that, h; therein, the relative thicknesses of the layer of active transporting material to the thickness of the layer of photoconductive material is 2: 1-200; I. 5. Electrophotographic element of PP. 1-4, characterized in that. As a quinacridone pigment, it uses a crystalline type of linear trans-quinacridone, chlorine, methyl, or methoxy-substituted linear transnanacridone. 6. Electrophotographic element on PP. 1-5, characterized in that a hole transporting material, for example, carbazole, N-ethylcarbazole, N-isopropylcarbazole, N-phenylcarbazole, tetraphenylpyrene, 1-methylpyrene, perylene, chrysene, fluorene, fluorenone, anthracene , tetrafen, tetracene, 2-phenylnaphthalene, aeapiren, 1-etilpiren, atsetshshiren, benzohrizen-2,3, 3,4-benzo, 1,4-brom1Tiren, phenylindole, polyvinylcarbazole, polivinilpiren, poliviniltetratsen, polkvinilperilen or poliviniltetrafen. An electrophotographic element according to claim 1-5, characterized in that it employs an electron-transporting material, such as 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranigrofluorenone, dipitroant acen, dinitroacridone, tetracyanopirech, dinitroantrahlon or polymers based on them. Sources of information taken into account in the examination: 1. US Patent No. 2821529, cl. 260-279, 1958. 2. US Patent No. 2821530, cl. 260-279, 1958. 3. US Patent No. 2830990, cl. 260-279, 1958. 4.AutoPass1Sgk certificate of the USSR No. 444380, cl. D2I f 5 02. 1971. 5.Arsk certificate of the USSR N 463275, M. class. G 03 C 5/06, 1971. 6. Author's certificate of the USSR N 497783, M. cl. SOZS5 / 06, 1971.

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