JPS638459B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a composite photoreceptor for electrophotography having two types of photoconductive layers each of which can receive and maintain charges of different polarity. Conventional Carlson using a photoreceptor with a single photoconductive layer (for example, an Se-based photoconductive layer; a photoconductive layer consisting of a charge generation layer and a charge transport layer; or a photoconductive layer further provided with an insulating layer on the photoconductive layer) Process-based color electrophotography involves repeating the charging-exposure-developing cycle multiple times depending on the color of the original, but this method requires: (1) each cycle consists of many steps, so the copying speed is There are limits to (2) Since colors are overlapped in each cycle, clear colors, especially black, are not produced, and color shift occurs. (3) Since a filter is used, an exposure amount 2 to 3 times the normal amount is required. , (4) There were drawbacks such as the complexity of the device. In addition, as a two-color electrophotographic method, it is possible to
A photoreceptor provided with an Se-based photoconductive layer and an insulating layer is subjected to primary corona charging, and at the same time or thereafter uniform exposure is performed. Next, originals having black areas and chromatic areas, such as red areas, are overlapped and a red complementary color filter is applied. At the same time, secondary corona charging with a polarity opposite to that of the primary charging is applied, and then image exposure is performed through a red filter to form latent images of different polarity, that is, sufficiently distinguishable, on the corresponding color portions of the document. A method has been proposed in which latent images are formed and then developed with toners of different polarity and color (Japanese Patent Laid-Open No. 144737/1983). This method simplifies the process and equipment compared to the color electrophotography method, and also
Although there is an advantage that there is no need to layer colors,
The point of using a filter remains the same. Therefore, in order to improve this two-color electrophotography method, the present inventors created a film on a conductive substrate that is sensitive to some chromatic light in the visible light range and that can transmit other chromatic light. A composite photoreceptor in which two photoconductive layers and a first photoconductive layer sensitive to at least chromatic light transmitted through the second photoconductive layer are laminated in the order of the first photoconductive layer and the second photoconductive layer. said first photoconductive layer by a process of applying a positive or negative primary corona charging and then applying a secondary corona charging of a polarity different from that of the primary charging, or similarly after applying the primary corona charging, or simultaneously. Alternatively, uniformly exposing the second photoconductive layer to chromatic light capable of making it conductive, and then similarly applying secondary corona charging to uniformly hold charges of different polarities in each of the photoconductive layers, and then proposed a method in which a latent image of different polarity was formed in each color-corresponding part of the original by performing image exposure through an original having black parts and chromatic parts, and then developed in the same manner to obtain a two-color copy. . An object of the present invention is to provide a composite photoreceptor for electrophotography which can reproduce originals having black areas and chromatic areas in a distinguishable manner using the above-mentioned simple color electrophotographic method without using a filter, and which has excellent surface properties. It is to provide. That is, the photoreceptor of the present invention has a second photoconductive layer that is sensitive to some chromatic light in the visible light range and that can transmit other chromatic light; A first photoconductive layer sensitive to chromatic light is laminated on a conductive substrate in the order of the first photoconductive layer and the second photoconductive layer, and this is subjected to positive or negative primary corona charging. Thereafter, the first photoconductive layer or the second photoconductive layer may be made conductive by a process of applying a secondary corona charge of a polarity different from that of the primary charge, or similarly after or simultaneously with the primary corona charge. After uniformly exposing each photoconductive layer to chromatic light and then similarly applying secondary corona charging to uniformly hold charges of different polarities, an original having black areas and chromatic areas is prepared. In the composite photoreceptor for electrophotography, in which latent images of different polarities are formed on portions of a document corresponding to respective colors by performing imagewise exposure through a photoreceptor, the first photoconductive layer is an Se-based photoconductive layer, and The second photoconductive layer is characterized in that its main components are a eutectic complex of a pyrylium dye and an electrically insulating polymer, and silicone oil. Here, the first photoconductive layer may be a single layer type mainly composed of amorphous Se or amorphous Se containing Te or As, or a charge generation layer of Se or Se-based alloy (this layer is directly applied on the substrate). It may be of a laminated type consisting of a charge transport layer (provided) and a charge transport layer containing a charge transport material as a main component. Therefore, the basic structure of the photoreceptor of the present invention is as shown in FIG.
And as shown in FIG. 2, a laminated first photoconductive layer 3 consisting of a charge generation layer 31 and a charge transport layer 32 on a conductive substrate 2 and a second photoconductive layer 4 provided thereon 1 ′. Although not shown, an intermediate layer is provided between the first photoconductive layer 3 or 3' and the second photoconductive layer 4, and an intermediate layer is provided between the substrate 2 and the first photoconductive layer 3 or 3'. A barrier layer can be provided. Furthermore, the second photoconductive layer 4 is similar to the laminated first photoconductive layer 3',
It can have a two-layer structure including a charge generation layer and a charge transport layer. In this case, the charge generation layer mainly contains a eutectic complex, and the charge transport layer contains a charge transport substance and, if necessary, a binder. In order to make the photoreceptor of the present invention, in the case of the one shown in FIG. It is sufficient to form a film. The thickness of this first photoconductive layer 3 is suitably about 10 to 150 μm. In the case of FIG. 2, Se or Se-based alloy is first vacuum-deposited on the conductive substrate 2 to a thickness of 0.3 to 5 μm, preferably 0.5 to 3 μm, and the charge generation layer 3 is
1, and then apply a solution containing a charge transport substance and a binder if necessary, and dry it to a thickness of 5 to 50 ml.
The first photoconductive layer 3' is provided by forming a charge transport layer of 40 .mu.m, preferably 7 to 30 .mu.m. Next, the thus obtained first photoconductive layer 3 or 3'
A solution containing a eutectic complex, silicone oil, a binder if necessary, and preferably a triphenylmethane sensitizer is applied thereon and dried to form the second photoconductive layer 4. The amounts of pyrylium dye and silicone oil in the second photoconductive layer are each based on the weight of the second photoconductive layer.
Appropriate amounts are approximately 0.5-4% and 0.05-3%. Further, the thickness of the second photoconductive layer is preferably about 5 to 50 μm. When a sensitizer is used, the amount of the sensitizer used is preferably about 10 to 60% of the weight of the second photoconductive layer. In addition, when providing an intermediate layer and/or a barrier layer, a binder solution as described below is applied and dried, or an inorganic material such as Al ₂ O ₂ , SiO, SiO ₂ , MgF ₂ is applied by vacuum evaporation, sputtering, etc. Thickness by method 0.01 ~
It is formed to have a thickness of about 5 μm, preferably about 0.1 to 2 μm. Next, materials used in the present invention will be explained. As the conductive substrate, any material can be used as long as it has a conductive layer with a volume resistance of 10 ¹⁰ Ω・cm or less.
For example, metal plates such as Al, Cu, and Pb, SnO ₂ , In ₂ O ₃ ,
Examples include plates made of metal compounds such as CuI and CrO ₂ , or plastic films, paper, or cloth coated with these compounds by vapor deposition or sputtering. The first photoconductive layer must be sensitive to at least the chromatic light transmitted through the second photoconductive layer, as described above. Therefore, the photoconductive material used in the first photoconductive layer must have such properties. In the case of a single layer type photoconductive material according to the present invention, the photoconductive material having such properties is mainly composed of amorphous Se or amorphous Se containing Te or As.
Here, the amorphous Se containing Te and As is Te or
A material with an As content of 20wt% or more is used. Note that when the single-layer type first photoconductive layer is formed by a resin dispersion method, a binder as described below can be used. On the other hand, in the case of a laminated type first photoconductive layer, Se or a Se-based alloy is used for the charge generation layer, and a material containing a charge transport substance as a main component is used for the charge transport layer. Se-based alloys used for the charge generation layer include Se to Te.
(Te40wt.% or less), Se~As (As40wt.% or less), Se
~Sb (Sb23wt.% or less), Se~Sb~As alloys, etc. are mentioned. Examples of the charge transport material used in the charge transport layer include the following. A compound containing at least one of an alkyl group such as a methyl group, an alkoxy group, an amino group, an imino group, and an imido group, or a polycyclic aromatic compound such as anthracene, pyrene, phenanthrene, coronene, or indole in the main chain or side chain, carbazole,
Oxazole, isoxazole, thiazole,
imidazole, pyrazole, oxadiazole,
Low molecular weight electron-donating compounds having nitrogen-containing cyclic compounds such as thiadiazole and doriazole, specifically hexamethylenediamine, N-(4-aminobutyl)yodaverine, as-didodecylhydrazine, p-toluidine, 4-amino -o-xylene, N・N'-diphenyl-1,2-diaminoethane, o-, m- or p-ditolylamine, diphenylmethane, triphenylmethane, tetraphenylmethane, triphenylamine, diurene, 2
-bromo-3,7-dimethylnaphthalene, 2.
3,5-trimethylnaphthalene, N'-(3-bromphenyl)-N-(β-naphthyl)urea, N'-
Methyl-N-(α-naphthyl)urea, N・N′-diethyl-N-(α-naphthyl)urea, 2,6-dimethylanthracene, anthracene, 2-phenylanthracene, 9,10-diphenylanthracene, 9,9'-bianthranil, 2-dimethylaminoanthracene, phenanthrene, 9-aminophenanthrene, 3,6-dimethylphenanthrene, 5,7-dibromo-2-phenylindole, 2,3-dimethylindoline , 3-indolylmethylamine, carbazole, 2-methylcarbazole, N-ethylcarbazole, 9-phenylcarbazole, 1,1'-dicarbazole, 3-
(p-methoxyphenyl)oxazolidine, 3.
4,5-trimethylisoxazole, 2-anilino-4,5-diphenylthiazole, 2,4.
5-trinitrophenylimidazole, 4-amino-3,5-dimethyl-1-phenylpyrazole, 2,5-diphenyl-1,3,4-oxadiazole, 1,3,5-triphenyl-1,2・
4-triazole, 1-amino-5-phenyltetrazole, bis-diethylaminophenyl-
1,3,6-oxadiazole, etc. can be used, and poly-N-vinylcarbazole and its derivatives (for example, poly-N-vinylcarbazole and its derivatives (for example, those having substituents such as halogens such as chlorine and bromine, methyl groups, and amino groups in the carbazole core) Polymer electron-donating compounds such as polyvinylpyrene, polyvinylanthracene, pyrene-formaldehyde condensation polymers, and derivatives thereof (for example, those having substituents such as halogens such as bromine or nitro groups in the pyrene bone core) can be used. It is. Furthermore, binders that can be used with these charge transport materials include polyethylene, polystyrene, polybutadiene, styrene-butadiene copolymers, polymers and copolymers of acrylic esters or methacrylic esters, polyesters, polyamides,
Polycarbonate, epoxy resin, urethane resin, silicone resin, alkyd resin, cellulose resin, poly-N-vinylcarbazole and its derivatives (for example, if the carbazole core has a halogen such as chlorine or bromine, or a substituent such as a methyl group or an amino group) polyvinylpyrene, polyvinylanthracene, pyrene-formaldehyde condensation polymers and derivatives thereof (for example, those having a halogen such as bromine or a substituent such as a nitro group on the pyrene core), poly-γ-carbazolylethyl- Examples include L-glutamate, styrene resin, chlorinated polyethylene, acetal resin, and melamine resin. A plasticizer can be used in combination with these binders. As the plasticizer, those commonly used as plasticizers for resins, such as dibutyl phthalate and dioctyl phthalate, can be used as they are. Next, the second photoconductive layer must be sensitive to some chromatic light in the visible light range and transmit other chromatic light. Therefore, the photoconductive composition used in the second photoconductive layer must have such properties. In the present invention, as a photoconductive composition having such properties, a eutectic complex of a pyrylium dye and an electrically insulating polymer, and preferably a composition further containing a triphenylmethane sensitizer can be used.
Here, pyrylium dyes mean pyrylium dyes, thiapyrylium dyes, and selenapyrylium dyes. Pyrylium dye has the following general formula. In the above formula, R ^a , R ^b , R ^c , R ^d and R ^c each represent a hydrogen atom (a) a hydrogen atom (b) an alkyl group, typically methyl, ethyl, propyl, isopropyl, butyl, t-butyl,
_C1 - _C15 alkyl groups such as amyl, isoamyl, hexyl, octyl, nonyl, dodecyl, etc. (c) Alkoxy groups such as methoxy, ethoxy, propoxy, butoxy, amyloxy, hexoxy, octoxy, etc. (d) Phenyl, 4-diphenyl, Alkylphenyls such as 4-ethylphenyl and 4-propylphenyl; 4-ethoxyphenyl, 4-methoxyphenyl, 4-amyloxyphenyl, 2-hexoxyphenyl, 2-methoxyphenyl,
Alkoxyphenyls such as 3,4-dimethoxyphenyl; β such as 2-hydroxyethoxyphenyl and 3-hydroxyethoxyphenyl
-Hydroxyalkoxyphenyl; 4-hydroxyphenyl, 2,4-dichlorophenyl,
Halophenyls such as 3,4-dibromophenyl, 4-chlorophenyl, 3,4-dichlorophenyl; azidophenyl, nitrophenyl, 4
- Aminophenyls such as diethylaminophenyl and 4-dimethylaminophenyl; naphthyl, styryl, methoxystyryl, diethoxystyryl, dimethylaminostyryl, 1-butyl-4-p-dimethylaminophenyl-1 and 3
- represents an aryl group including substituted aryl groups such as vinyl-substituted aryl groups such as butadienyl, β-ethyl-4-dimethylaminostyryl, X is a sulfur, oxygen or selenium atom, and Z ^- is perchlorate, Anionic functional groups such as fluoroborate, iodide, chloride, bromide, sulfate, periodide, p-toluenesulfonate, hexafluorophosphate. Furthermore
R ^a , R ^b , R ^c , R ^d and R ^e may be atoms necessary to jointly complete the aryl ring fused to the pyrylium nucleus. Representative examples of such pyrylium dyes are shown below.

[Table] -Chlorate

[Table] 7 4-(4-dimethylaminophenyl)-
2,6-Diphenylthiapyrylium hexafluorophosuto Particularly useful pyrylium dyes are those having the general formula: In the formula, R ₁ and R ₂ are C ₁ to C ₆ alkyl groups and C ₁ to _{C 6}
is an aryl group such as _a substituted phenyl group having _at least one substituent selected from the alkoxy _groups of It may also be a substituted phenyl group. X is an oxygen or sulfur atom, and Z ^- is as described above. As an electrically insulating polymer, the main chain (repeat unit)
Particularly useful are those having an alkylidene diarylene moiety represented by the following formula. In the formula, R ₄ and R ₅ each represent a hydrogen atom, methyl containing a substituted alkyl group such as trifluoromethyl,
Ethyl, propyl, isopropyl, butyl, t-
Aryl groups such as phenyl and naphthyl, including alkyl groups such as butyl, bentyl, hexyl, heptyl, octyl, nonyl, decyl, substituted aryl groups having substituents such as halogen, C1 _{- C5} alkyl groups, Furthermore, R ₄ and R ₅ may be carbon atoms necessary to jointly form a cyclic hydrocarbon group including cycloalkanes such as cyclohexyl and polycycloalkanes such as norbornyl. R ₅ and R ₇ are hydrogen, a C ₁ to C ₆ alkyl group, or halogen such as chloro, bromo, iodine, and R ₈ is

【formula】 【formula】

【formula】

【formula】

【formula】

【formula】 as well as

[Formula] is a divalent group selected from the group consisting of: Hydrophobic carbonate polymers (polycarbonates) comprising repeating units of the following formula are also useful and preferred. In the formula, R is a phenylene group including halo-substituted phenylene groups and alkyl-substituted phenylene groups, and R ₄ and R ₅ are as described above. These polymers are disclosed in USP 3,028,365 and USP 3,317,466. Preferably, a compound containing an alkylidene diarylene moiety in the repeating unit, such as prepared from bisphenol A, is produced by transesterification between diphenyl carbonate and 2,2-bis(4-hydroxyphenyl)propane. Polycarbonates containing such polymers are useful. Such polymers are disclosed in USP2999750, USP3038874,
Same No. 3038880, No. 3106544, No. 3106545, Same No.
It is disclosed in No. 3106546 etc. In any case, film-forming polycarbonate resins can be used in a wide variety of ways. Satisfactory results are obtained especially when using those having an intrinsic viscosity of about 0.5 to 1.8. Specific examples of the electrically insulating polymer are as follows.

【table】

[Table] Also, as a triphenylmethane sensitizer, 4.
4'-bis(diethylamino)-2,2'-dimethyltriphenylmethane, 4,4'-bis(diethylamino)-2,2'-dimethyl-2''-chlorotriphenylmethane, 4,4',4'' Examples include -tris(diethylamino)-2,2'-dimethyltriphenylmethane. The intermediate layer prevents the injection of free charge carriers between the photoconductive layers and accumulates and retains the charge (the polarity of the charge is positive because the first photoconductive layer uses a selenium-based photoconductive material) at the interface between the photoconductive layers. For the former purpose, the above binder or SiO ₂ ,
A white or transparent high-resistance (10 ⁸ Ωcm or more) inorganic compound such as Al ₂ O ₂ , MgO, MgF ₂ , SnO ₂ , CdS, etc. is coated as is by a method such as solvent coating, vapor deposition, or sputtering, or it is coated with the above-mentioned plasticizer and the above-mentioned. Electron-donating low-molecular compounds, including high-resistance inorganic compounds (compounds containing at least one of alkyl groups, alkoxy groups, amino groups, imino groups, and imido groups; polycyclic aromatic compounds such as anthracene, pyrene, and phenanthrene; The layer contains nitrogen-containing cyclic compounds such as oxazole, imidazole, indole, carbazole, etc.) at 70% by weight or less based on the entire intermediate layer, and the remainder is a binder. On the other hand, for the second purpose, N-type photoconductive substances, electron-accepting substances (carboxylic acid anhydrides, compounds with electron-accepting core structures such as o- or p-quinoid structures, nitro groups, nitrososulfate, etc.) are used. aliphatic cyclic compounds, aromatic compounds, or heterocyclic compounds having electron-accepting substituents such as cyano groups, cyano groups, etc.), the above-mentioned electron-donating low-molecular compounds or electron-donating high-molecular compounds, including plasticizers. (Poly-N-vinylcarbazole and its derivatives, polyvinylpyrene, polyvinylanthracene, pyrene-formaldehyde condensation polymer and its derivatives, etc.) is 70% by weight or less of the entire intermediate layer, and the remainder is a binder. . The intermediate layer contains sulfur, barium chromate, barium dichromate, cesium oxide, chromium oxide, cobalt chloride, cobalt sulfate, indium sulfate, and ferrocyanide as appropriate for the purpose of controlling the color sensitivity of the first photoconductive layer. Inorganic compounds such as iron oxide, iron ferricyanide, molybdenum chloride, nickel chloride, tin iodide, tin sulfide, or Hansa Yellow,
It is also possible to add organic coloring substances such as benzidine yellow, permanent red, benzidine orange, brilliant first scarlet, watching red, resol red, spring blue BV, and other organic pigments or dyes. . Note that the thickness of the intermediate layer is suitably 0.05 to 5 μm. The barrier layer is provided for the purpose of providing rectifying properties against the movement of the carrier, and the binder or high-resistance inorganic compound described above can be used.
The formation method is the same as that for the intermediate layer. Next, a specific example of an electrophotographic process applied to the composite photoreceptor of the present invention will be described with reference to FIGS. 3 to 6. In the following explanation, for the sake of simplicity, "other chromatic light" and "chromatic light transmitted through the second photoconductive layer" will be used.
are the same, and these are abbreviated as "light A", and "partially chromatic light in the visible light region" is abbreviated as "light B". Process - The photoreceptor 1, 1' applied to this process has a first photoconductive layer 3, 3' sensitive to light B, a second photoconductive layer 4 transmitting light B, and sensitive to light A. It is something that has. Therefore, for a photoreceptor having such properties, the first photoconductive layer 3 has a polarity opposite to the polarity to which it is sensitive, or the first photoconductive layer 3 has a charge polarity that can be injected from the substrate 2. After performing positive or negative primary corona charging with the opposite polarity, the photoreceptor is uniformly exposed to light A alone or to light that includes light A but does not include light B. This uniform exposure may be performed simultaneously with the primary charging, but if the first photoconductive layer 3 has the property of receiving charge injection from the substrate 2 during the primary charging, the uniform exposure is performed by performing the primary charging in the dark. Unnecessary (3rd
-a figure). Next, after performing secondary corona charging with a polarity opposite to that of the primary charging (FIG. 3-b), an optical image of the original 5 is applied to this photoreceptor. In this case, the secondary charging is performed at a lower potential than the primary charging potential so that the polarity of the surface potential of the photoreceptor is reversed. At this time, there is no change in the charge distribution in the part corresponding to the black part of the document, and the current photoreceptor surface potential is maintained in a secondary charged state, but the charge distribution in the part corresponding to the white part is Both the first photoconductive layers 3, 3' and the second photoconductive layer 4 become conductive, and the charges accumulated in both layers disappear through neutralization and dissipation, and the surface potential of the photoreceptor at this point becomes almost zero. . On the other hand, the chromatic color part of the original 5 (for example, the color A part)
In the portion corresponding to , the first photoconductive layer 3, 3' becomes conductive, and a part of the charge existing at the interface between the first photoconductive layer 3, 3' and the second photoconductive layer 4 and the conductive layer 3, 3' become conductive. Although the charges existing at the interface between the substrate 2 and the first photoconductive layers 3 and 3' are neutralized, some charges remain,
At this point, the surface potential of the photoreceptor becomes negative (third
-c figure). Here, a latent image with surface potential divided into positive, negative, and zero is formed on the photoreceptor, and in order to visualize this, it is developed with two types of toner, positively charged toner 6 and negatively charged toner 7. do it. The two types of toner used here may be any type of toner as long as they differ in hue, brightness, purity, gloss, etc. For example, toner 6 colors are color A, and toner 7 is different. If it is made black, a copy corresponding to the original 5 can be obtained (Fig. 3-d). Incidentally, FIG. 4 shows the state of the surface potential of the photoreceptor over time through this process. In the above description, the primary charge is negative and the secondary charge is positive, but the same result can be obtained even if the charge polarity is reversed. Process - The photoreceptor applied to this process has a first photoconductive layer 3, 3' sensitive to light B and a second photoconductive layer 4
transmits light B and is sensitive to light A. Therefore, a photoreceptor having such properties is subjected to positive or negative primary corona charging of the same polarity as the polarity to which the second photoconductive layer 4 exhibits sensitivity. At this time, uniform exposure to light A to make the second photoconductive layer 4 conductive is performed at the same time as or immediately after charging. However, if the second photoconductive layer 4 has a property of transferring charges during primary charging, the primary charging is performed in the dark, and uniform exposure is not necessary (Figure 5-a). Next, after performing secondary corona charging with a polarity opposite to that of the primary charging (FIG. 5-b), an optical image of the original 5 is applied to this photoreceptor. In this case, the secondary charging is performed at a lower level than the primary charging potential. At this time, there is no change in the charge distribution of the portion of the photoreceptor corresponding to the black portion of the original 5, but the charge distribution of the portion corresponding to the white portion of the photoreceptor is such that both the first and second photoconductive layers 3, 3', and 4 are conductive. and the charge disappears. On the other hand, in the chromatic portion of the original 5, for example, the portion corresponding to the color A portion, the second photoconductive layer 4 becomes conductive, and the charges on the second photoconductive layer 4 are transferred between the second photoconductive layer 4 and the first photoconductive layer. Although some of the charges existing at the interface with 3 and 3' are neutralized, some charges remain, and the surface potential of the photoreceptor at this location becomes positive (Figure 5-c). Here, electrostatic latent images with different polarities corresponding to the black and chromatic parts of the original 5 are formed on the photoreceptor, and these are subsequently applied to the chromatic toner 6' and the black toner 7 in the same manner as in the process described above. If the image is developed sequentially in steps ', a two-color copy is obtained (Fig. 5-d). This process is advantageous because the black image portion is formed by an external latent image. Incidentally, FIG. 6 shows the state of the surface potential of the photoreceptor over time through this process. In the above description, the primary charge is negative and the secondary charge is positive, but the same result can be obtained even if the charge polarity is reversed as long as the conditions are satisfied. Further, the photoreceptor of the present invention can be processed by the above-mentioned process.
, but can also be applied to the normal Carlson process. Further, the original document is not limited to two colors as in the above example, but may be multicolored. If such a multicolor original is used, for example, in a normal Carlson process (monochrome copying), each color portion can be copied in black and white with significant density differences. According to the present invention, the intended purpose can be achieved by adopting the above configuration. The reason for using silicone oil in the second photoconductive layer is to improve the surface properties of the second photoconductive layer and improve image characteristics. That is, in general, when manufacturing a composite photoreceptor having two types of photoconductive layers, a eutectic complex is used as a constituent material of the second photoconductive layer.
When coating to a thickness of 30 μm, there was a problem that the surface layer became rough and had a negative effect on image characteristics.
By adding silicone oil to the coating liquid for the second photoconductive layer as in the present invention, this problem can be solved without reducing the sensitivity. Examples are shown below. Example: An Al substrate is heated to 60℃, and Te is heated at this temperature.
Se doped with 6 wt% was deposited to a thickness of 25 μm to form a first photoconductive layer. On top of this, a novolac resin (CP-918 manufactured by Gunei Chemical Co., Ltd.) was coated by a dipping method to form an intermediate layer of 1 μm thickness. Ta. Further, a photosensitive solution having the following composition was applied thereon by a doctor blade method, and then dried at 50° C. for 10 minutes to form a second photoconductive layer with a thickness of 25 μm, thereby obtaining a composite photoreceptor with a smooth surface. p-Dimethylaminophenyl-2,6-diphenylthiapyrylium chlorate 0.6g 4,4'-bis(diethylamino)-2,2'-dimethyltriphenylmethane 12.0g Polycarbonate (Teijin Panlite K-
1300) 17.4g Silicone oil 0.1wt.% of total solid content Methylene dichloride 300ml For comparison, a composite photoreceptor was manufactured in the same manner except that silicone oil was removed from the photosensitive solution for the second photoconductive layer. The surface layer of this product was rough, like uneven coating. Next, each of the photoreceptors obtained as described above is primary charged by -6KV corona discharge in a dark place, and at the same time uniformly exposed to red light through a red filter. When image exposure was performed on the bottom of the two-color original, and finally it was developed with red toner and then black toner, a clear copy in two colors, red and black, with no background smudge was obtained with the product of the present invention, but in comparison In the case of products, red and black mixed images, color loss, background stains, etc. occurred in rough areas on the surface, and the image characteristics were very poor.

[Brief explanation of the drawing]

1 and 2 are block diagrams of an example of the composite photoreceptor of the present invention, FIGS. 3 and 5 are explanatory diagrams of an example of an electrophotographic process applied to the composite photoreceptor of the present invention,
FIGS. 4 and 6 are surface potential state diagrams corresponding to FIGS. 3 and 5, respectively. 1,1′...Composite photoreceptor, 2...Electroconductive substrate,
3, 3′...first photoconductive layer, 4...second photoconductive layer,
5... Original, 6, 6', 7, 7'... Toner, 31
...Charge generation layer, 32...Charge transport layer.

Claims (1)

[Claims] 1. A second photoconductive layer that is sensitive to some chromatic light in the visible light region and can transmit other chromatic light;
a first photoconductive layer sensitive to at least chromatic light transmitted through the second photoconductive layer; the first photoconductive layer and the second photoconductive layer are laminated in this order on a conductive substrate; by a process of applying a positive or negative primary corona charge to the surface and then applying a secondary corona charge of a polarity different from that of the primary charge, or similarly after applying the primary corona charge, or simultaneously with said first photoconductive charge. A process of uniformly exposing the photoconductive layer or the second photoconductive layer to chromatic light capable of making it conductive, followed by secondary corona charging, allows each of the photoconductive layers to uniformly hold charges of different polarities. rear,
In the composite photoreceptor, the surface potential for each color of the original appears as different polarity by performing image exposure through an original having a black area and a chromatic area. a two-color electrophotographic composite, characterized in that the second photoconductive layer is mainly composed of a eutectic complex of a pyrylium dye and an electrically insulating polymer, and silicone oil. Photoreceptor.