JPS638458B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an electrophotographic photoreceptor, and more particularly to an electrophotographic composite photoreceptor that can perform not only ordinary black-and-white copying but also two-color color copying from a multicolor original in a single exposure step. Copying to obtain ordinary black and white images uses the Carlson process, in which an electrophotographic photoreceptor with a photoconductive layer on a conductive substrate is used, and the surface of the photoreceptor is charged, exposed, and developed. A process is used in which the generated electroscopic particle image is transferred to paper or the like and further fixed. As a typical photoreceptor applied to such a process, a selenium-based photoreceptor or a photoreceptor in which a charge transfer layer of polyvinylcarbazole or the like is provided on a selenium photoconductive layer is known. Incidentally, such photoreceptors are sometimes used to make black and white copies from multicolor originals including black and colored originals, but in this case, the copied image area corresponding to the chromatic areas of the original is the background area or the black area. There were times when it was difficult to identify the manuscript, and people disliked it when some of the manuscript information was missing. Similarly, when making two-color copies from a multicolor original, the photoreceptor is charged, exposed, and
The drawback was that the development-transfer process had to be repeated twice. Repeating this process will
Not only is the copying speed slow, but because the colors are uneven, clear colors, especially black, are not produced, and color misalignment occurs. Reflecting this fact, we have developed an insulating layer/photoconductive layer/
Using an electrophotographic photoreceptor made of a conductive substrate,
First, after primary corona charging or at the same time, the entire surface of the photoreceptor is irradiated with light from the sensitive area of the photoconductive layer, and then the original having white, black, and red areas is passed through a red complementary color filter. At the same time as image exposure, secondary corona charging with a polarity opposite to the primary charging of the photoconductor is applied, and further image exposure is performed again through a red filter, thereby reducing the electrostatic charge in the red and black areas corresponding to the original. A state is created on the photoreceptor in which the charge polarity of the latent image is different. A method has been proposed in which this latent image is then sequentially developed with toners of different colors and different polarities, and this is transferred and fixed when the image is received on paper, etc., to obtain a two-color copy (Japanese Unexamined Patent Publication No. 144737/1983). ). However, even this method has drawbacks such as the trouble of applying two different filters and the need for a considerable amount of exposure. Therefore, at present, electrophotographic photoreceptors are used in which two photoconductive layers, each sensitive to light of different wavelengths, are laminated on a conductive substrate, and this is charged with a primary charge.
Secondary charging is performed by performing secondary charging with a polarity different from primary charging, or after primary charging, or at the same time, uniform exposure to light with a wavelength that can make one photoconductive layer conductive is performed, and then secondary charging is performed, Electrostatic charges are generated by causing each photoconductive layer to maintain charges of different polarity, and then exposing the image to light through an original having a black area and a chromatic area, so that the surface potential corresponding to each color area of the original becomes different in polarity. A new electrophotographic method is attracting attention, in which a latent image appears on a photoreceptor, this is sequentially developed with different color toners of different polarities, and this toner image is transferred to receiver paper and fixed to obtain a two-color copy. . However, although this method enables two-color copying with simpler operations than the method described in JP-A-53-144737, there are still unresolved problems with the photoreceptor itself used. However, satisfactory copies have not always been obtained. The purpose of the present invention is to provide a product that is used in the latter process (an electrostatic latent image is formed with one image exposure), has good adhesion between each layer, has good separation potential, and good photosensitivity, and provides a clear image at all times. An object of the present invention is to provide a composite photoreceptor for electrophotography that allows copies to be obtained. Another object of the present invention is to provide a composite photoreceptor for electrophotography that can be easily produced. That is, the present invention provides a second photoconductive layer that is sensitive to some chromatic light in the visible light range and transmits other chromatic light; The first photoconductive layer, the intermediate layer, and the second photoconductive layer are laminated in this order on a conductive substrate. The first photoconductive layer or the second photoconductive layer may be made conductive by a process of applying secondary corona charging with a polarity different from the polarity of the charging, or after or simultaneously with primary corona charging. A uniform exposure to chromatic light followed by a similar secondary corona charging process causes each of the photoconductive layers to maintain a charge of a different polarity, and then an image is transferred through the document having black and chromatic areas. In a two-color electrophotographic composite photoreceptor in which surface potentials corresponding to each color portion appear as different polarities when exposed to light, the first photoconductive layer is formed mainly of selenium or a selenium alloy, and the first photoconductive layer is formed mainly of selenium or a selenium alloy; The second photoconductive layer is formed mainly of a eutectic complex consisting of a pyrylium dye and a resin and a charge transfer substance, and the intermediate layer is formed mainly of a phenolic resin. It is something. The present invention will be explained in more detail below based on the accompanying drawings. FIG. 1 shows a typical example of the photoreceptor of the present invention, and the numbers assigned thereto are 1.
11 represents a photoreceptor, 11 represents a conductive substrate, 12 represents a first photoconductive layer, 13 represents an intermediate layer, and 14 represents a second photoconductive layer. The conductive substrate 11 is made of a metal plate such as Al, Cu, or Pb, or a metal oxide such as SnO ₂ , In ₂ O ₃ , CuI, or CrO ₂ having a volume resistance of 10 ¹⁰ Ωcm or less. Alternatively, plastic films (eg, polyester films), paper, or cloth coated with these metal oxides by vapor deposition or sputtering may be used. The first photoconductive layer 12 is formed of a deposited layer of Se or a selenium alloy. As a Se alloy, Se
−Te (Te content is 40% by weight or less, preferably 20% by weight)
(wt% or less), Se-As (As content is 40 wt% or less, preferably 20 wt% or less), Se-Sb (Sb content is 23 wt% or less, desirably 10 wt% or less),
Examples include Se-Sb-As. The thickness of this first photoconductive layer 12 is 3 to 180 μm, preferably 5 to 180 μm.
Approximately 150 μm is appropriate. The second photoconductive layer 14 is formed mainly of a eutectic complex and a charge transfer substance. The eutectic complex here is made from a pyrylium dye (pyryllium, thiapyrylium, selenapyrylium, etc.) and a resin (an electrically insulating polymer having an alkylidene diarylene moiety). Pyrylium dye has the following general formula. In the above formula, R ^a , R ^b , R ^c , R ^d and R ^e are each (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] Rupyrillium perchlorate

[Table] Apyrillium perchlorate

[Table] Chiapyrylium perchlorate

[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. 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 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: Hydrophobic carbonate polymers (polycarbonates) comprising repeating units of the following formula are also useful and preferred. In the formula, R ⁹ 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 described in USP 2999750, USP 3038874,
No. 3038880, No. 3106544, No. 3106645, 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] Carbonate Block Oxytetramethylene)
On the other hand, together with this eutectic complex, the second photoconductive layer 14
The charge transfer material constituting the photoconductive layer 12 may be a material that is transparent to visible light or has a pale color even if it is colored, and that can effectively inject and transfer the charges generated in the first photoconductive layer 12, such as polyvinyl carbazole or the like. It is a polyarylalkane. Specific examples of polyarylalkane include (1) 1,3-diphenyl-2-p-diethylaminophenyl-tetrahydroindazole (2) bis(p-(N·N-dibenzyl)aminophenyl)methane (3) 1- Bis(p-(N・N-dibenzyl)aminophenyl)propane(4) 4・4′-bis(diethylamino)-2・2′-
Dimethyltriphenylmethane (5) 4,4'-bis(diethylamino)-2,2'-
Dimethyl-2″-chlorotriphenylmethane (6) α・α-bis(2-methyl-4-diethylaminophenyl)-2-methylthiophene (7) α・α-bis(2-methyl-4-diethylaminophenyl) enyl)-2-picoline(8) α・α-bis(2-methyl-4-diethylaminophenyl)-2-methylfuran(9) α・α-bis(2-methyl-4-diethylaminophenyl)- 2-Methylpyrrole (10) α・α-bis(2-methyl-4-diethylaminophenyl)-2-methylindole(11) α・α-bis(2-methyl-4-diethylaminophenyl)-2- Methylbenzothiophene (12) α・α-bis(2-methyl-4-diethylaminophenyl)-2-methylbenzofuran (13) 4・4′・4″-tris(diethylamino)-
Examples include 2,2'-dimethyltriphenylmethane. Among them, it is preferable to use triphenylmethane. In the second photoconductive layer 14, the proportion of the charge transport substance in the layer 14 is suitably 10 to 60% by weight. Further, the proportion of the pyrylium dye in the eutectic complex in the layer 14 is required to be 0.5 to 8% by weight.
When the amount of pyrylium dye is less than 0.5% by weight, the amount of eutectic complex decreases, resulting in poor sensitivity.On the other hand, when it exceeds 8% by weight, the repeatability of the photoreceptor deteriorates, that is, charge transfer becomes progressively worse. There is a tendency to The thickness of the second photoconductive layer 14 is suitably about 3 to 100 μm, preferably about 5 to 50 μm. This second photoconductive layer 14 can be easily formed into the intermediate layer 13 by a resin dispersion method.
can be formed on top. Note that a binder may be used if necessary for forming this layer. The binder materials here include polyethylene, polystyrene, polybutadiene, styrene-butadiene copolymer, acrylic ester or methacrylic ester polymer and copolymer, polyester, polyamide, polycarbonate, epoxy resin, urethane resin, silicone. resins, alkyd resins, cellulose resins, poly-N-vinylcarbazole and its derivatives (for example, those having a halogen such as chlorine or bromine, or a substituent such as a methyl group or an amino group in the carbazole core), polyvinylpyrene, polyvinylanthracene, Pyrene-formaldehyde condensation polymers and derivatives thereof (for example, those having a pyrene core with a halogen such as bromine or a substituent such as a nitro group), poly-γ-carbazolylethyl-L-glutamate, styrene resin, chlorinated polyethylene , acetal resin, melamine resin, etc. A plasticizer can be used in combination with this binder. As the plasticizer, those commonly used as plasticizers for resins, such as dibutyl phthalate and dioctyl phthalate, can be used as they are. The appropriate amount to be used is about 0 to 30% by weight based on the resin binder. Examples of the organic solvent used to form the second photoconductive layer 14 include toluene, tetrahydrofuran, 1,2-dichloroethane, methylene chloride, and benzene. The intermediate layer 13 is provided between the first photoconductive layer 12 and the second photoconductive layer 14, and is made of phenolic resin. Phenol resins include (a) resol type resins obtained by reacting an excess of formaldehyde with respect to phenol in the presence of an alkali catalyst, and (b) a resol type obtained by reacting an excess of phenol with respect to formaldehyde in the presence of an acid catalyst. There is a novolak type obtained by reaction,
Both can be used. Table 1 shows the main raw materials for producing phenolic resin.

【table】

[Table] It tends to be faster.

【table】

[Table] Furthermore, as the acid catalyst, any of those listed in Table 3 can be used, and the larger the dissociation constant of the acid, the better the results.

[Table] Hexamethylenetetramine, acetals (methylal, dioxirane, trioxane), furifural or furifural alcohol can also be used instead of formaldehyde. Of course, it is also possible to form the phenolic resin layer (intermediate layer 13) without using these catalysts, but in that case it is necessary to raise the curing temperature somewhat. As a solvent, without catalyst, water>cyclohexanol>i-propanol≒
In the order of butanol > ethanol > methanol, in the case of hydrochloric acid catalyst, the order is cyclohexanol > i-propanol ≒ butanol > ethanol > methanol > water, and in the case of caustic soda catalyst, cyclohexanol >
The order of i-propanol≒butanol>water>methanol can be effectively applied. This intermediate layer 13 is made of a phenolic resin, but the phenolic resin may also contain modified products such as phenol derivatives, such as reaction products of polyhydric phenols and quinones, lignin modified products, and phenol ether modified products. included. The thickness of the intermediate layer 13 is 0.1 to 4.0 μm, preferably 0.3 to 2.0 μm.
m is appropriate. If it is thinner than 0.1 μm, it is difficult to obtain a good potential difference, and if it is thicker than 4.0 μm, a residual potential will occur, which is not preferable. It is generally believed that providing an intermediate layer is effective in reducing charge leakage, and the intermediate layer 13 naturally has this effect. In addition, as will be understood from the explanation of the electrophotographic process using the photoreceptor of the present invention, which will be described later, the photoreceptor of the present invention must be able to form patterns differentiated between positive and negative polarities by a single image exposure. middle layer 13
When a phenolic resin is used, an extremely good separation potential difference can be obtained. This is convenient for obtaining clear images. It is also possible to use polyester resin or nitrocellulose instead of phenolic resin,
When a polyester resin is used, the polyester resin dissolves when the second photoconductive layer forming liquid is applied, resulting in an uneven interface, resulting in poor image characteristics (resolution, sharpness, background staining), and two-color separation potential. There is a tendency to say that it is bad. In addition, when using nitrocellulose, there are disadvantages such as poor two-color separation potential and low contact strength, as well as inversion of white light attenuation and considerable residual potential, which can cause skin stains. Furthermore, there is a tendency that the white sensitivity of the first photoconductive layer and the second photoconductive layer is poorly matched. In order to actually produce the photoreceptor of the present invention, Se or Se alloy is formed as the first photoconductive layer 12 on the conductive substrate 11 by vapor deposition, sputtering, etc., and a phenolic resin solution (if necessary) is formed on the first photoconductive layer 12. (including curing catalyst) and cured at 50-70℃ for 30-90℃.
The intermediate layer 13 is formed by heating for about a minute, and then a solution containing a eutectic complex, a charge transfer substance, and a binder is coated on top of the intermediate layer 13, and heated at 40 to 70°C for about 5 to 20 minutes. What is necessary is to form the dual photoconductive layer 14. In this way, the photoreceptor of the present invention has a selenium or selenium alloy layer (first photoconductive layer 12), a second photoconductive layer 14 mainly composed of a eutectic complex and a charge transfer substance, and an intermediate layer 13 made of a specific material. The conductive substrate 11 is laminated on the conductive substrate 11 via the conductive substrate 11. In other words, in the photoreceptor of the present invention, since the first photoconductive layer 12 located below is made of Se or selenium alloy, it may or may not have a rectifying property. It is charged only when either of the corona charges is applied, and in the latter case, it is charged when either the positive or negative corona charge is applied, and by this charging, the surface potential receiving ability and maintenance ability are sufficient to develop colored electrostatic particles. have. Furthermore, when exposed to tungsten light with a color temperature of 3000〓, the electrophotographic sensitivity under both positive and negative corona charging shows high sensitivity without any noticeable difference, and the sensitivity to light in the wavelength range from 560 nm (red It also has the property that its sensitivity (sensitivity) is 0.8 times the sensitivity to light in the entire wavelength range (white sensitivity), which is almost the same. On the other hand, the second photoconductive layer 14 located above is sensitive to red light (for convenience, this will be referred to as "light A") and non-red light (for convenience, this will be referred to as "light B").
At the same time, it has sufficient surface potential receiving ability and maintaining ability to be charged when subjected to either positive or negative corona charging and to be developed with colored electrostatic particles. Therefore, two methods can be employed to obtain a copied image using the photoreceptor of the present invention. First photoconductive layer 1
An electrophotographic process using a photoreceptor in which photoreceptor 2 has rectifying properties is described as process 1, and an electrophotographic process using a photoreceptor in which first photoconductive layer 12 does not have rectifying properties is described as process 2. It is as follows. Process 1 The first photoconductive layer 12 has a polarity (negative) opposite to the polarity (positive) of the charge injected from the base 11 to the photoreceptor 1
Then, primary corona charging is applied in the dark (Figure 2-1).
Next, after performing secondary corona charging with a polarity opposite (positive) to the primary charging (FIG. 2-2), an optical image of the original 2 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 surface potential polarity of the photoreceptor is not reversed. Then, the charge distribution of the photoconductor in the area corresponding to the black area BL of the document does not change, and the potential after secondary charging is maintained on the photoconductor surface, but the area corresponding to the white area (background area) W remains unchanged. The charge becomes conductive in both the first photoconductive layer 12 and the second photoconductive layer 14, and disappears by neutralization or dissipation, and the surface potential of the photoreceptor becomes approximately zero. On the other hand, in areas corresponding to chromatic areas (for example, red area A) of the original 2, the second photoconductive layer 14 becomes conductive, and the interface between the charge on the surface of the photoreceptor and the intermediate layer 13 of the first photoconductive layer 12 becomes conductive. Although some of the charges existing on the photoreceptor are neutralized, some charges remain, and the surface potential of the photoreceptor is reversed to positive polarity (Fig. 2-3). Here, a latent image is formed on the photoreceptor with a surface potential divided into positive, negative, and zero, and in order to visualize this latent image, two types of toner are used: negatively charged toner shown in , and positively charged toner shown in . Develop with toner.
The two types of toner used here may be any toner as long as they differ in hue, brightness, purity, gloss, etc. For example, red toner
By developing with T _A and black toner T _B , a copy corresponding to original 2 can be obtained (Figure 2-4). Incidentally, FIG. 3 shows the surface potential state of the photoreceptor over time through this process 1. Process 2 The first photoconductive layer 12 applies primary corona charging to the photoreceptor 1 with the same polarity as the charge polarity (positive) injected from the base 11 . At this time, uniform exposure for making the second photoconductive layer 14 conductive with light A is performed simultaneously with or immediately after the primary charging (FIG. 4-1). Next, after performing secondary corona charging with a polarity opposite to that of the primary charging (FIG. 4-2), an optical image of the original 2 is applied to this photoreceptor. In this case, the secondary charging is performed so that the polarity of the photoreceptor surface potential is reversed, although the potential is less than the primary charging potential. Then, on the photoreceptor, there is no change in the charge distribution in the portion corresponding to the black portion BL of the document, but the charge in the portion corresponding to the white portion (background portion) W disappears. On the other hand, the surface potential of the photoreceptor corresponding to the chromatic portion (for example, red portion A) of the original appears as positive polarity, as in Process 1. Here, a latent image is formed on the photoreceptor with surface potentials classified into positive, negative, and zero, and this can be made noticeable in the same manner as in Process 1. Incidentally, FIG. 5 shows the surface potential state of the photoreceptor over time through this process 2. Both of the above two processes have the advantage that the black image is formed as an external latent image, so that the resolution and sharpness are further improved. The photoreceptor of the present invention, which has an electrostatic latent image after the exposure process, has a surface potential sufficient for electrostatic development of both positive and negative polarities.
The separation characteristics of the two colors are excellent. In addition, as mentioned above, the photoreceptor of the present invention has the second to fifth
It is applicable not only to the process shown in the figure, but also to the normal Carlson process. In particular, the sensitivity ratio of the second photoconductive layer and the first photoconductive layer (i.e., the sensitivity ratio of the first light when the second photoconductive layer alone and the second photoconductive layer or even the intermediate layer are used as a filter) For example, the sensitivity ratio with the conductive layer is 20
If the photoreceptor is made to be larger than 30 to 30,
The light attenuation of the surface potential upon image exposure is significantly accelerated, and the amount of exposure can therefore be extremely reduced, making it possible to particularly speed up black-and-white copying. Further, if the photoreceptor is manufactured so that the sensitivity ratio is smaller than, for example, 20 to 30, it becomes preferable for two-color image formation. The manuscript is not limited to two colors; it may be in multiple colors. If this multicolor original is used, each color portion of the chromatic color portion will be reproduced with significant density differences. Next, examples will be shown. Example 1 Se-Te alloy (Te content: 10% by weight) was deposited on a 0.2 mm thick aluminum plate (conductive substrate) at a substrate temperature of 65°C under a vacuum of 10 ^-5 torr.
A 16 μm thick Se-Te layer (first photoconductive layer) was formed. On top of this, phenolic resin (80% solution of methanol, CP-
918, manufactured by Gunei Kagaku KK) 25g p-toluenesulfonic acid 0.75g methanol 75g was applied using the dipping method, dried at 50℃ for 30 minutes to form a phenol resin layer (intermediate layer) with a thickness of about 1.2μm. ) was formed. Furthermore, 4-p-dimethylaminophenyl-2,6-diphenylthiapyrylium perchlorate 4.2g 4,4-bis(diethylamino)-2,2'-dimethylphenylmethane 4.0g Polycarbonate (Panlite) KK-1300, Teijin
(manufactured by KK) A solution consisting of 5.8g of methylene chloride and 100g of methylene chloride was applied using the blade method.
A second photoconductive layer having a thickness of about 20 .mu.m was formed by drying at .degree. C. for 15 minutes to produce a composite photoreceptor. This photoconductor is uniformly irradiated with white light (28μW/cm ² , 2854〓tungsten is used) through a filter that cuts out wavelengths of 600nm or less (Sharp Cut Filter R60, manufactured by Hoya Glass KK), and primary charging is performed to raise the surface potential to +1200V. After that, secondary charging was performed until the surface potential reached -460V. Furthermore, a part of the photoconductor in this state was shielded from light, and white light (14.8μW/
cm ² ), and was irradiated with white light, that is, red light (11.2 μW/cm ² ) passed through the sharp cut filter R60, the surface potential attenuated as shown in FIG. In this figure, W corresponds to the white part of the document, R corresponds to the red part, and BL corresponds to the black part. For comparison, two types of comparative photosensitizers were prepared, except that no intermediate layer was provided (comparative product 1), and nitrocellulose was used as the intermediate layer (comparative product 2). We created a body and examined the attenuation state of the surface potential using the same operation. The results were as shown in Figure 7. In addition,
In FIG. 7, the solid line represents comparative product 1, and the broken line represents comparative product 2. These measurements show that the photoreceptor of the present invention is excellent as a two-color photoreceptor. Furthermore, the adhesion of each layer of this photoreceptor was improved, and as a result of electron micrographs, it was confirmed that the intermediate layer (phenol resin) had a uniform thickness. Example 2 A substrate temperature of 65℃ on an aluminum plate with a thickness of 0.2mm.
Se is evaporated to a thickness of approximately 27 μm under a vacuum of 10 ^-5 Torr, and then Se-Te is deposited on top of this from another evaporation source.
A first photoconductive layer was formed by depositing an alloy (Te content: 10% by weight) to a thickness of about 5 μm. A phenol resin (MP-617 Gunei Chemical Co., Ltd.) was coated thereon by a dipping method and dried at 50° C. for 1 hour to form an intermediate layer with a thickness of about 1.0 μm. Furthermore, 4-p-dimethylaminophenyl-2,6-diphenylthiapyrylium perchlorate 0.3g 4,4'-bis(diethylamino)-2,2'-dimethyltriphenylmethane 4.0g Polycarbonate (Lexan) 141-111, manufactured by Engineering Plastics KK) A solution consisting of 5.7 g of methylene chloride and 100 g of methylene chloride was applied using the blade method.
℃ for 15 minutes to form a charge generation layer of the second photoconductive layer with a thickness of approximately 5 μm, and on top of this, 5.0 g of 4,4'-bis(diethylamino)-2,2'-dimethyltriphenylmethane (5.0 g of polycarbonate) ( A solution consisting of 5.0 g of Lexan 141-111) and 60 g of methylene chloride was applied using the blade method.
A composite photoreceptor was prepared by drying at 0.degree. C. for 15 minutes to provide a charge transport layer of the second photoconductive layer approximately 21 .mu.m thick. This photoreceptor was primary charged in a dark place to a surface potential of +1800V, and then secondary charged until the surface potential reached -740V. Next, the photoreceptor in this state was irradiated with light in the same manner as in Example 1, and the attenuation of the surface potential was measured as shown in FIG. In addition, after applying a similar primary charge to this photoreceptor, it is exposed to light through a document consisting of black and red images on a transparent background under similar secondary charging, and then the red and black areas are removed using a two-component developer. When developed sequentially, a clear two-color image was obtained.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view of a photoconductor according to the present invention, FIGS. 2 to 6, and 8 are diagrams for explaining an electrophotographic method using this photoconductor, and FIG. 7 is a comparative photoconductor. FIG. 3 is a diagram showing the state of surface potential. 1... Photoreceptor, 11... Conductive substrate, 12...
First photoconductive layer, 13... intermediate layer, 14... second photoconductive layer.

Claims (1)

[Claims] 1. A second photoconductive layer that is sensitive to part of the chromatic light in the visible light range and transmits other chromatic light, and a first photoconductive layer that is sensitive to the chromatic light that passes through the second photoconductive layer. The photoconductive layer is formed by laminating a first photoconductive layer, an intermediate layer, and a second photoconductive layer on a conductive substrate in this order, and after applying positive or negative primary corona charging to this layer, the polarity of the primary charging is determined. is a process of applying secondary corona charging of different polarity, or similarly after or simultaneously with primary corona charging, uniform chromatic light that can make the first photoconductive layer or the second photoconductive layer conductive. When a photoconductive layer is exposed to light and then subjected to a similar secondary corona charging process to maintain charges of different polarities on each of the photoconductive layers, and then subjected to imagewise exposure through an original having a black area and a chromatic area. In the composite photoreceptor in which the surface potential corresponding to each color portion appears as different polarity, the first photoconductive layer is formed mainly of selenium or a selenium alloy, and the second photoconductive layer is formed of pyrylium dye and 1. A composite photoreceptor for two-color electrophotography, characterized in that the composite photoreceptor is formed mainly of a eutectic complex made of resin and a charge transfer substance, and the intermediate layer is formed mainly of a phenol resin.