JPS638455B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic composite photoreceptor having two photoconductive layers each of which can receive and maintain charges of different polarities. To obtain a color copy using the conventional Carlson process, a photoreceptor with a single photoconductive layer, such as a selenium photoreceptor, is used, and the charging-exposure-development cycle is repeated for each color of the original. However, with this method, (1) each cycle consists of many processes, so there is a limit to the copying speed; (2) colors are overlapped in each cycle, so clear colors, especially black, cannot be produced, and it is difficult to mix colors, There were disadvantages such as fogging, color shift, etc., (3) since a filter was used, an exposure amount 2 to 3 times the normal amount was required, and (4) the device was complicated. In addition, as a two-color electrophotographic method, Se
A photoreceptor provided with a photoconductive layer and an insulating layer is subjected to primary corona charging, and at the same time or thereafter uniform exposure is performed, and then originals having black areas and chromatic areas, such as red areas, are stacked and passed through a red complementary color filter. At the same time, a secondary corona charge with a polarity opposite to that of the primary charge is applied, and then image exposure is performed through a red filter to form a latent image on the corresponding color portion of the document, which has a different polarity and can therefore be differentiated. A method has been proposed in which latent images are formed, and then each latent image is developed with toner of different polarity and color (Japanese Patent Application Laid-Open No. 1986-1999).
Publication No. 144737). This method has simpler steps and equipment than the color electrophotographic method, and does not require color overlapping; however, it is still the same in that a filter is used during image exposure. Therefore, in order to improve this two-color electrophotography method, the present inventors created a second layer on a conductive substrate that is sensitive to some chromatic light in the visible light range and that can transmit other chromatic light. A photoconductive layer and a first photoconductive layer sensitive to chromatic light transmitted through at least the second photoconductive layer are laminated in the order of the first photoconductive layer and the second photoconductive layer. After applying a negative primary corona charge, the first photoconductive layer or the second photoconductive layer is applied by a process of applying a secondary corona charge of a polarity different from the polarity of the primary charge, or similarly after applying the primary corona charge, or at the same time. The two photoconductive layers are uniformly exposed to chromatic light that can make them conductive, and then the photoconductive layers are uniformly charged with different polarities by a process of similarly applying secondary corona charging. We previously proposed a method in which a latent image of different polarity is formed on each color-corresponding portion of the original by performing image exposure through an original having chromatic light and then developed in the same manner to obtain a two-color copy. . The present invention is an electrophotographic composite that can clearly separate the wavelengths of each color of a color original by such two-color electrophotography method that does not use a filter during image exposure, and can therefore form sufficiently distinguishable latent image charges. An object of the present invention is to provide a photoreceptor. 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 can transmit other chromatic light, and a photoconductive layer that transmits at least the second photoconductive layer. A first photoconductive layer sensitive to colored light is laminated on a conductive substrate in the order of the first photoconductive layer and the second photoconductive layer, and after this is subjected to positive or negative primary corona charging. , 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 similarly to the application of 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 a composite photoreceptor for two-color electrophotography, in which latent images of different polarities are formed on portions of an original corresponding to each color by performing imagewise exposure through , the second photoconductive layer consists of a single layer mainly composed of a eutectic complex of pyrylium or thiapyrylium salt and polycarbonate, or a charge generating layer mainly composed of the eutectic complex and a triphenylmethane electron donating layer. It consists of a composite layer with a charge transport layer made of a substance and a binder, and if the first photoconductive layer is an Se layer, a binder is the main component between the substrate and the first photoconductive layer. It is characterized by having a subbing layer. The photoreceptor of the present invention will be explained with reference to the drawings. Figures 1 and 2 show the basic structure of the composite photoreceptor of the present invention,
1 is a conductive substrate, 2 is a first photoconductive layer made of a Se-Te alloy, 2' is a first photoconductive layer made of Se, and 3 is a eutectic complex-based single layer or a eutectic complex-based charge The second photoconductive layer is a composite layer of a generation layer and a triphenylmethane charge transport layer, and 10 is a binder-based subbing layer. Further, in the present invention, as shown in FIGS. 3 and 4, an intermediate layer 11 made of an organic or inorganic material can be provided between the first photoconductive layer 2 and the second photoconductive layer 3. In the case of the photoreceptors shown in FIGS. 1 and 3, an undercoat layer can be provided between the substrate 1 and the first photoconductive layer 2 in the same manner as in the photoreceptor shown in FIG. The thickness of the first photoconductive layer is 5 to 30 μm, preferably 10 to 30 μm.
The thickness of the second photoconductive layer is 10 to 50 μm in the case of a single eutectic complex layer, preferably 10 to 20 μm, and the thickness of the second photoconductive layer is from a composite layer of a eutectic complex charge generation layer and a triphenylmethane charge transport layer. In this case, the charge generation layer has a thickness of 2 to 10 μm, preferably 3 to 5 μm, and the charge transport layer has a thickness of 5 to 30 μm, preferably 7 μm.
~15 μm, i.e. 7-40 μm in total thickness of these layers
m, preferably 10 to 20 μm. Further, the thickness of the subbing layer is 0.1 to 5 μm, preferably 0.2 to 3 μm,
The thickness of the intermediate layer is 0.01-5μm, preferably 0.1-2μm
m is appropriate. Next, the photoreceptor of the present invention will be explained using the examples shown in FIGS. 1 and 2. In the case of the photoreceptor shown in FIG. A first photoconductive layer is formed by depositing approximately 4 to 8 wt.% Se-Te alloy at a vacuum level of 5 x 10 ^-5 Torr or less, and a layer containing pyrylium salt or thiapyrylium salt and polycarbonate as main components is formed on the first photoconductive layer. Either a solution of the eutectic complex is coated and dried to form a eutectic complex-based second photoconductive layer, or this eutectic complex-based layer is used as a charge generation layer for the second photoconductive layer, and a triphenylmethane-based electron layer is further applied thereon. A charge transport layer for the second photoconductive layer may be formed by applying and drying a solution containing a donor substance and a binder as main components. On the other hand, in the case of the photoreceptor shown in FIG. 2, a solution or dispersion containing a binder and, if necessary, a pigment such as copper phthalocyanine or chlordian blue is coated on a conductive substrate and dried to form an undercoat layer. Next, the Se-coat of the photoreceptor shown in FIG. 1 is applied to the substrate having the subbing layer.
The first photoconductive layer is formed by vacuum deposition of Se under the same conditions as the deposition conditions of the Te alloy layer, and the second photoconductive layer is formed in the same manner as in the case of the photoreceptor shown in FIG. 1. In both of the photoreceptors shown in Figures 1 and 2, to form the intermediate layer, if an organic material is used, a coating method is usually used, and if an inorganic material is used, a vapor deposition method or sputtering method is usually used. Apply the law. 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 pyrylium or thiapyrylium dye used in the second photoconductive layer has the following general formula. In the above formula, R ^a , R ^b , R ^c , R ^d and R ^e each represent (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, periodate, 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]

[Table] Rate

【table】

[Table] Sfuoto
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
It is an aryl group such as a substituted phenyl group having at least one substituent selected from C ₆ alkoxy groups, and R ₃ is an alkylamino-substituted phenyl group in which the alkyl moiety is C ₁ to C ₆ , dialkylamino-substituted and It may also be a haloalkylamino substituted phenyl group. X is an oxygen or sulfur atom, and Z ^- is as described above. Main chain (repeat unit) for polycarbonate
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, pentyl, 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 ₆ and R ₇ are hydrogen, a C ₁ to C ₆ alkyl group, or halogen such as chloro, bromine, 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: 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 polycarbonate are as follows.

[Table]

[Table]
The ratio of pyrylium or thiapyrylium dye to polycarbonate used in the eutectic complex photoconductive layer is preferably about 1:5 to 1:60 (by weight). Further, an electron-donating compound such as a triphenylmethane compound such as crystal violet or malachite green may be added to the above-mentioned eutectic photoconductive layer, if necessary. On the other hand, as the binder used in the charge transport layer of the second photoconductive layer or the subbing layer, polyethylene, polystyrene, polybutadiene, styrene-butadiene copolymer, acrylic ester or methacrylic ester polymer and copolymer are used. Examples include polymers, polyesters, polyamides, polycarbonates, epoxy resins, polyurethanes, silicone resins, alkyd resins, various polyvinyl resins, celluloses, and polyimides. The ratio of the triphenylmethane electron donating substance and the binder in the charge transport layer is 1:2 to 2:1.
(weight) is appropriate. Further, as the organic material used for the intermediate layer, the above-mentioned binders can be used as they are. As the inorganic material, SiO ₂ , SiO, MgF ₂ , Al ₂ O ₃ and the like are used. Next, to explain more specifically the process applied to the photoreceptor of the present invention, first, in the case of the photoreceptor shown in FIGS. 1 and 3, the following process-, process-
, process. In the following description, for the sake of simplicity, "other chromatic light" and "chromatic light transmitted through the second photoconductive layer" are the same, and this is abbreviated as, for example, red light "light A", and " For example, non-red light "partially chromatic light in the visible light region" is abbreviated as "light B". Process - The photoreceptor applied to this process is one in which the first photoconductive layer 2 is sensitive to light A, and the second photoconductive layer 3 is transparent to light A and sensitive to light B. Therefore, for a photoreceptor having such properties, first, the first photoconductive layer 2 has a polarity opposite to the polarity to which it exhibits sensitivity, or the first photoconductive layer 2 has a polarity of charges that can be injected from the substrate 1. After applying positive or negative primary corona charging with opposite polarity (here, for convenience, it is referred to as "negative charging"), the photoreceptor is uniformly exposed to only light A or light that includes light A but does not include light B. This uniform exposure may be performed at the same time as the primary charging, but if the first photoconductive layer 2 has the property of receiving charge injection from the substrate 1 during the primary charging, the uniform exposure is performed after performing the primary charging in the dark. is not necessary (Fig. 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 4 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 original, and the current photoreceptor is The body surface potential is maintained in a secondary charged state, but the charge distribution in the area corresponding to the white area is primary,
Both the second photoconductive layers 2 and 3 become conductive, and the charge accumulated in both layers disappears by neutralization and dissipation, and the surface potential of the photoreceptor at this point becomes approximately zero. on the other hand,
In the part corresponding to the A color part (for example, the red part) of the original 4, the first photoconductive layer 2 becomes conductive, and part of the charge existing at the interface between the first photoconductive layer 2 and the second photoconductive layer 3 is Although the charge existing at the interface between the conductive substrate 1 and the first photoconductive layer 2 is neutralized, some charge remains, and the surface potential of the photoreceptor becomes negative at this point (fifth -c figure). Here, a latent image is formed on the photoreceptor with surface potentials classified into positive, negative, and zero, and in order to visualize this latent image, use the positively charged toner 5 shown in , and the negatively charged toner 6 shown in . It is sufficient to develop with two types of toner. The two types of toner used here are hue,
Any color may be used as long as it differs in brightness, purity, gloss, etc. For example, if it is developed with red toner and black toner, a copy corresponding to original 4 can be obtained (Fig. 5-d). ). 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. Process - The photoreceptor applied to this process has a first photoconductive layer 2 sensitive to light B and a second photoconductive layer 3 sensitive to light B.
, and is sensitive to light A. Therefore, a photoreceptor having such properties is subjected to positive or negative primary corona charging (herein referred to as "positive charging" for convenience) having the same polarity as the polarity to which the first photoconductive layer 2 exhibits sensitivity. At this time, uniform exposure to light A to make the second photoconductive layer 3 conductive is performed at the same time as or immediately after charging. However, if the second photoconductive layer 3 has the property of transferring charges during primary charging, the primary charging is performed in the dark, and uniform exposure is not necessary (Figure 7-a). Next, after performing secondary corona charging with a polarity opposite to that of the primary charging (FIG. 7-b), an optical image of the original 4 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 of the photoreceptor in the part corresponding to the black part of the original 4, but the charge distribution in the part corresponding to the white part becomes conductive with the first and second photoconductive layers 2 and 3. , the charge disappears. On the other hand, although the second photoconductive layer 3 becomes conductive in the chromatic portion of the original 4, for example, the portion corresponding to the red portion,
Some charges remain (Figure 7-c). Here, electrostatic latent images with different polarities corresponding to the black and chromatic parts of the original 4 are formed on the photoreceptor, and these are subsequently transferred to negatively charged toner 5' and positively charged toner 6' in the same manner as in the process. A two-color copy can be obtained by sequentially developing with two types of toner (Section 7-d).
figure). This process is advantageous because the black image portion is formed by an external latent image. Incidentally, FIG. 8 shows the state of the surface potential of the photoreceptor over time through this process. In the above description, the primary charge is positive and the secondary charge is negative, but the same result can be obtained even if the charge polarity is reversed. Process - In the photoreceptor applied to this process, the first photoconductive layer 2 is sensitive to light B, and when charged, receives charge injection for one charging polarity, and the second photoconductive layer 3 is sensitive to light B. It has the property of transmitting light B and being sensitive to light A. Therefore, for a photoreceptor having such properties, the first photoconductive layer 2 has a polarity opposite to the charge polarity that can be injected from the substrate 1, and the second photoconductive layer 3 has a polarity that is primary and has a polarity that exhibits sensitivity. Corona charging (here, negative charging is used for convenience) is performed in the dark (Figure 9-a). Next, after performing secondary corona charging with a polarity opposite to that of the primary charging (FIG. 9-b), an optical image of the original 4 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 not reversed. 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 4, but the charge distribution of the portion of the photoreceptor corresponding to the white portion is such that both the first and second photoconductive layers 2 and 3 are conductive. , the charge disappears. On the other hand, the second photoconductive layer 3 becomes conductive in a chromatic color part of the original 4, for example, a part corresponding to a red part, and the charges on the second photoconductive layer 3 and the first and second photoconductive layers Although some of the charges existing at the interface with 3 are neutralized, some charges remain, and the surface potential of the photoreceptor at this point is reversed and appears as positive polarity (Figure 9-c). Here, electrostatic latent images with different polarities corresponding to the black and chromatic portions of the original 4 are formed on the photoreceptor.
In the same way as in the process, negatively charged toner 5',
A two-color copy can be obtained by successive development with positively charged toner 6' (FIG. 9-d). This process is advantageous because the black image area is formed by an external latent image. Incidentally, FIG. 10 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.
, , and 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 of multiple colors. 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. On the other hand, in the case of the photoreceptors shown in FIGS. 2 and 4, the above process is applied as is, but since the first photoconductive layer 2 has a rectifying property, the polarity of primary charging and secondary charging may be reversed. I can't. Next, the effects of the photoreceptor of the present invention will be explained in the case of the photoreceptors shown in FIGS. 1 and 3 as follows. (1) In the case of a composite photoreceptor in which the first photoconductive layer is an Se vapor-deposited layer (without an undercoat layer), wavelength separation is not possible, but it is possible with the photoreceptor of the present invention. (2) The amount of exposure required for the first photoconductive layer to form a discernible latent image is smaller than that of a Se-based one (Comparative Example 1, Example 1,
(See Figure 12). (3) Applicable to the normal Carlson process in which corona charging is performed with negative polarity. Also, Figures 2 and 4
The case of the photoreceptor shown in the figure is as follows. (1') Similar to (1) above, wavelength separation is possible. (2') Since the primary charging potential can be increased, the black-white and red-white separation potentials can be increased. (3') Adhesion between the substrate and the Se layer is improved, resulting in flexibility. (4′) Similar to (3) above, it can also be applied to the Carlson process. Examples are shown below. Comparative example 1 A 0.2mm thick Al plate was held at 70℃ and Se was added to it.
A first photoconductive layer is formed by vacuum deposition to a thickness of 21 μm,
On top of that, a 10 wt.% methyl alcohol solution of cellulose resin (Jiyado Co., Ltd.) was applied and dried to form an intermediate layer with a thickness of 1.5 μm.
-p-dimethylaminophenyl-2,6-diphenylthiopyrylium perchlorate 0.2g, 4.
A solution consisting of 4.2 g of 4'-bis(diethylamino)-2,2'-dimethyltriphenylmethane, 5.6 g of polycarbonate (Teijin Panlite K1300) and 80 g of methylene chloride was applied and dried to form a 20 μm thick second photoconductive layer. A composite photoreceptor was obtained by providing layers. Example 1 A 0.2mm thick Al plate was held at 60℃, and Te5wt.
%-containing Se-Te alloy was vacuum deposited to form a 20 μm thick first photoconductive layer, and then an intermediate layer and a second photoconductive layer of a eutectic complex system single layer were formed thereon in the same manner as in Comparative Example 1. A composite photoreceptor was obtained. Next, while irradiating the photoreceptors of Comparative Example 1 and Example 1 with 60 lux light through a red filter, +
Perform primary corona charging at 6.5KV, then -
After performing secondary corona charging of 5.0KV, each process includes (a) dark decay, (b) irradiation with 7lux light (white exposure), and (c) irradiation with 7lux light through a red filter (red exposure). was applied to measure the surface potential in each case, and the results shown in FIG. 11 (Comparative Example 1) and FIG. 12 (Example 1) were obtained. Note that curves a, b, and c in the figure correspond to the aforementioned processes (a), (b), and (c), respectively. As can be seen from this figure, the first photoconductive layer is Se-Te.
The photoreceptor of Example 1, which is made of an alloy layer, has a lower maximum positive potential especially when exposed to white light than Comparative Example 1, whose first photoconductive layer is made of an Se layer, and as a result, a large positive potential can be produced with a small amount of exposure. Red-white and black-white potential differences can be obtained. Example 2 A 3 wt.% methylene chloride solution of a copper phthalocyanine-polycarbonate mixture (mixing ratio 1:2 by weight) (polycarbonate is the same as in Example 1) was applied to a 0.2 mm thick Al plate by dipping, and dried to a thickness of 1 μm. A thick subbing layer was provided. Next, this was held at 65°C, and Se was vacuum-deposited in this state to form a 19 μm thick Se layer, and on top of that a Se-Te alloy with a Te content of 6 wt.% was deposited under the same conditions to form a 3 μm thick Se layer. A thick Se-Te alloy layer is provided as a first photoconductive layer, and then an intermediate layer and a second photoconductive layer consisting of a single eutectic complex layer are provided thereon in the same manner as in Comparative Example 1 to form a composite photoreceptor. I got it. Next, this photoreceptor was subjected to primary corona charging and secondary corona charging in the same manner as in Example 1, and then the black, red, and white portions of the original were image-exposed. (1) Dark decay 3 to correspond to
(2) irradiation with 7 lux light for 3 seconds, and (3) irradiation with 7 lux light through a red filter for 7 seconds.The results of measuring the surface potential at that time were -
They were 680V, -30V and +300V. Note that both of the photoreceptors of Examples 1 and 2 were also applicable to the Carlson process in which corona charging is of negative polarity. Comparative Example 2 A 0.2 mm thick Al plate was held at 50°C and Se was vacuum evaporated onto it to form a 13 μm thick first photoconductive layer, and then a second photoconductive layer of an intermediate layer and a eutectic complex single layer was formed. Comparative Example 1 except that the thickness of the conductive layer was 1 μm and 18 μm, respectively.
An intermediate layer and a second photoconductive layer were formed in the same manner as described above to obtain a composite photoreceptor. Example 3 A 5 wt.% tetrahydrofuran solution of polyester (polyester 49000 manufactured by Dupont) was coated on a 0.2 mm thick Al plate by a dipping method and dried to form a 0.5 μm thick undercoat layer, followed by the same method as in Comparative Example 2. A first photoconductive layer, an intermediate layer, and a second photoconductive layer were provided to obtain a composite photoreceptor. Next, while irradiating the photoreceptors of Comparative Example 2 and Example 3 with 50 lux light through a red filter, +
Apply primary corona charging of 6.5KV, then -5.0KV
After secondary corona charging of Irradiate light for 4 seconds and (3) 7lux through red filter
Each process of irradiating with light for 4 seconds was applied, and the surface potential at that time was measured, and the results shown in the table below were obtained. Process Comparison Example 2 () Example 3 () (1) −500 −550 (2) −20 +70 (3) +300 +440 Comparative Example 3 A 0.2 mm thick Al plate was held at 70°C, and Se was applied to it in a vacuum. A first photoconductive layer having a thickness of 19 μm was formed by vapor deposition, and the intermediate layer and the first photoconductive layer of a eutectic complex system single layer were formed in the same manner as in Comparative Example 1 except that the thickness of the intermediate layer was 1 μm as in Comparative Example 1. A composite photoreceptor was obtained by providing two photoconductive layers. Example 4 A 3 wt.% methylene chloride solution of a mixture of copper phthalocyanine and polyester (same as in Example 3) (mixing ratio 1:3 by weight) was applied on a 0.2 mm thick Al plate by dipping method and dried to a thickness of 0.4 μm. A thick subbing layer was provided, and then an intermediate layer and a second photoconductive layer were provided in the same manner as in Comparative Example 3 to obtain a composite photoreceptor. Next, the surface potential of each photoreceptor of Comparative Example 3 and Example 4 was measured according to the method described in Example 3, and the results shown in the table below were obtained. Process Comparison Example 3 () Example 4 () (1) -550 -600 (2) +70 0 (3) +340 +400 The photoreceptor of Example 4 can also be applied to the normal Carlson process in which corona charging is of negative polarity. did it. Example 5 A 3 wt.% methylene chloride solution of polyester resin (Bylon 200 manufactured by Toyobo Co., Ltd.) was applied to a 0.2 mm thick Al plate by dipping and dried to form a 0.6 μm subbing layer, and then heated to 70°C. While holding, Se was vacuum deposited to provide a 19 μm thick first photoconductive layer. Next, 4-p-dimethylaminophenyl-2,6-
Diphenylthiopyrylium perchlorate 0.2g,
A solution consisting of 2 g of 4,4'-bis(diethylamino)-2,2'-dimethyltriphenylmethane, 2.8 g of the same polycarbonate as in Example 1, and 60 g of methylene chloride was coated and dried to form a 5 μm thick second photoconductive layer. A charge generation layer is provided, and a solution consisting of 2 g of 4,4'-bis(diethylamino)-2,2'-dimethyltriphenylmethane, 2 g of the polycarbonate, and methylene chloride is applied thereon and dried to form a 7 μm thick second layer. A charge transport layer for a photoconductive layer was provided to obtain a composite photoreceptor. Next, this photoreceptor was evaluated according to the method of Example 3, and the results shown in the table below were obtained. Furthermore, even when the photoreceptors of Examples 3, 4, and 5 were wound around a cylinder with a diameter of 80 mm, no cracking or peeling occurred in the Se layer. Process example 5 () (1) −400 (2) −50 (3) +200

[Brief explanation of the drawing]

1 to 4 are configuration diagrams of an example of the composite photoreceptor of the present invention, FIGS. 5, 7, and 9 are explanatory diagrams of an example of an electrophotographic process applied to the composite photoreceptor of the present invention, and FIG. 6 , 8 and 10 show surface potential state diagrams corresponding to FIGS. 5c, 7c and 9c, respectively. FIG. 11 and FIG. 12 show the state of the surface potential after exposure obtained in Comparative Example 1 and Example 1, respectively. DESCRIPTION OF SYMBOLS 1... Conductive substrate, 2... First photoconductive layer, 3...
...Second photoconductive layer, 4...Original, 5, 5', 6,
6'...Toner, 10... Subbing layer, 11... Intermediate 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; and a first photoconductive layer and a second photoconductive layer stacked in this order on a conductive substrate. 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, after uniformly exposing the second photoconductive layer to chromatic light that can make it conductive, and then similarly applying secondary corona charging, the photoconductive layers are made to uniformly hold charges of different polarities. ,
In an electrophotographic composite photoreceptor in which latent images of different polarities are formed on portions of the document corresponding to each color by performing image exposure through a document having black areas and chromatic areas, the first photoconductive layer is made of Se or Se. The second photoconductive layer is made of a Se-Te alloy metal, and the second photoconductive layer is made of a single layer mainly composed of a eutectic complex of pyrylium or thiapyrylium salt and polycarbonate, or a charge generating layer mainly composed of the eutectic complex. It consists of a charge transport layer made of a triphenylmethane-based electron donating substance and a binder, and in the case of the first photoconductive layer Se layer, a binder is mainly used between the substrate and the first photoconductive layer. A composite photoreceptor for two-color electrophotography, comprising a subbing layer as a component.