Electrophotography photosensitive member and a method for fabricating same

Abstract: Disclosed is an electrophotography photosensitive member (10) and a method for fabricating same. This electrophotography photosensitive member (10) comprises a straight chain compound polymer including (i) as main component, a straight chain compound polymer having p-phenylene in the direction of a main chain, and element of VIb group at a para-position, the element of VIb group being one of S, Se and Te; and oxygen atom. Since oxygen atom is included in the straight chain compound polymer, desirable characteristics are obtained. This photosensitive member (10) is produced at a low cost with a high productivity, thereby providing a high sensitivity, an excellent printing durability and a long lifetime.

Description: This invention relates to a process for producing an electrophotographic photosensitive member used, for example, for a copying machine of an electrophotographic type, a photo printer or the like, and photosensitive members obtainable by this process. Conventionally, in an electrophotographic photosensitive member, the function-separated type of the electrophotography photosensitive member is widely used which comprises layers of different materials. One is a carrier transport layer for transporting carrier and the other is a carrier generation layer for generating carrier due to optical pumping. By selecting the material having a particular function, an excellent photosensitive member having a highly sensitive electrophotography property can be provided. Moreover, the most suitable combination of materials can be investigated from the perspectives of mechanical strength, thermal stability, printing durability and manufacturing cost. Moreover, various kinds of organic materials have become of major interest and are actively investigated. There are many electrophotographic photosensitive members comprising a carrier transport layer and a carrier generation layer, and organic materials are used therefor. For example, used are the combination of methyl squaric acid and triaryl pyrazoline, the combination of dyanblue and oxadiazole, the combination of perylene pigment and oxadiazole, the combination of bis-azo pigment and styrian anthracene and the like. Further, inorganic materials can also be used as the carrier generation layer, in combination with an organic transport layer. For example, used are the combination of amorphous silicon as the carrier generation layer and organic semiconductor material as carrier transport layer which was disclosed in Japanese Laid-open Patent Application No. 54-143645, and the combination of amorphous selenium and polyvinylcarbazole. These combinations are of the function-separated type. However, in the function-separated type of photosensitive members comprising the combination of organic materials, there are the problems that printing durability is poor, lifetime is short, and reliability is poor. In such photosensitive members using organic materials, the carrier generation layer, the carrier transport layer, and moreover, a surface layer for increasing the hardness of the surface or the like are formed on a sheet-like substrate of an endless belt or the like, or on a cylindrical drum made by a cutting method or a molding method such as an impact method. In this case, it is necessary to uniformly form each of the layers in accordance with the process for producing the electrophotography. As the methods by which each of such layers is formed, there are dip coating methods, spray coating methods using a spray gun, and a US-spray coating method using ultrasonic waves. However, these methods require large plant and equipment investment. Moreover, in the combination of the inorganic materials in the carrier generation layer and the organic materials in the carrier transport layer, the use of an inorganic carrier generation layer having a large hardness as the surface layer in order to improve the printing durability has been studied. However, in order to maintain good properties, many carrier generation layers having an excellent printing durability require the heating of the substrate or require a process such as the method using plasma by which the surface is heated to a high temperature. In this case, since the organic carrier transport layer has an inferior heat resistance, a photosensitive member having good properties cannot be obtained. Of such methods described above, Japanese Laid-open Patent Application No. 55-90954 and Japanese Laid-open Patent Application No. 60-59353 discloses that PPS (poly-p-phenylene sulfide) film used as the carrier transport layer provides an excellent member which can be cheaply produced, and that PPS film is a deposition polymer film having a high carrier mobility. However, it is necessary for the electrophotographic photosensitive member to have a small dielectric constant, a large mobility, a large carrier lifetime, and a large capacity for generating carrier in order to have a high sensitivity. Therefore, in the function-separated type photosensitive member, it is desirable to combine the carrier transport layer having the large mobility and the large carrier lifetime and the carrier generation layer having the large capacity for generating carrier. However, it is necessary to carry out efficiently a carrier injection between both layers, even if each of the layers satisfies the necessary conditions. Moreover, it is necessary to satisfy sufficiently the properties such as abrasion resistance, a capacity for accepting carrier, and the like which are required for the process of electrophotography. Japanese Laid-open Patent Application No. 55-90954 discloses that PPS is formed into thin film and the capacity for transporting carrier of PPS is improved by the method of vacuum deposition, and that the resulting film is applied to the carrier generation layer. However, the resulting carrier transport layer has a small capacity for transporting carrier, and does not have a sufficient sensitivity and a good residual electric potential. Besides, the velocity for making the film is slow because of the vacuum deposition method. Therefore, the resulting photosensitive member is of high cost among the photosensitive members using organic materials. Moreover, the resulting film does not have sufficient hardness and sufficient printing durability. Japanese Laid-open Patent Application No. 55-90954 has disclosed that a photosensitive member can be cheaply produced, by applying the PPS film to the carrier generation layer. However, the photosensitivity does not reach the level for the practical use of the electrophotography photosensitive member, because of the insufficient capacity for transporting carrier. Moreover, the function-separated type of the photosensitive member using organic materials has a problem when miniaturizing an electrophotography apparatus because this photosensitive member is used by charging negatively, and has also a problem that this photosensitive member has an effect on human bodies because of the generation of ozone. US-A- 3408190 discloses an electrophotographic plate comprising a support substrate having fixed to the surface thereof a photoconductive charge transfer complex material comprising a mixture of a Lewis acid and a polysulfone resin comprising the recuring units having the formula : The present invention has been developed in order to remove the above-mentioned drawbacks inherent to the conventional photosensitive members for use in electrophotography. It is, therefore, an object of the present invention to provide a photosensitive member for use in electrophotography which is cheap, is produced with a high productivity, and obviates the need for a coating apparatus. Another object of the present invention is to provide a high performance photosensitive member which has a high sensitivity, an excellent printing durability, and a long lifetime. The other object of the present invention is to provide a photosensitive member for use in electrophotography which can be used in the range of charging positively, has a high sensitivity and a low residual electric potential, and is inexpensive. In accordance with the present invention there is provided a process for producing an electrophotographic photosensitive member (10) which comprises providing on a substrate (1,5) either a single layer (6) combining carrier transport and carrier generation functions or a separate carrier transport layer (2) and a carrier generation layer (3), characterised in that said single layer (6) or separate carrier transport layer (2) is a layer containing a straight chain compound polymer comprising as main component units of the formula in the main chain, wherein X is S, Se or Te, which has been treated at a temperature of from 250°C to 350°C for from 0.2 to 50 hours in an atmosphere containing oxygen to introduce oxygen atoms into said polymer such that the ratio of the number of oxygen atoms to the number of carbon atoms in said thermally treated straight chain compound polymer is from 1:100 to 35:100 and such that the layer comprising the thermally treated straight chain compound polymer has a Vickers hardness of 10 to 80. Thermal treatment is preferably effected at 260°C to 290°C for from 1 to 12 hours. The layer comprising the thermally treated straight chain compound may further comprise an electron acceptor. A surface covering layer (8) may be formed on the resulting photosensitive member. The layer containing the straight chain compound polymer may be formed by applying to a substrate surface a film of the straight chain compound polymer produced by a biaxial stretching method so as to have a drawing magnification of 1.5 to 6.0 in at least one direction and carrying out the thermal treatment. A process according to the invention may therefore comprise providing on a substrate (1): (a) a carrier generation layer (3) for generating carrier by optical pumping; and (b) said layer containing said thermally treated straight chain compound polymer as a carrier transport layer (2) for transporting said carrier. The carrier generation layer (3) may comprise non-single crystal layer including a modification material for decreasing electron spin density and including atoms of at least one of Si and Ge. Alternatively, the carrier generation layer (3) may comprise a non-single crystal layer including at least one chalcogen element. The carrier generation layer (3) optionally has a Vickers hardness of 100 or more at room temperature and is on said carrier transport layer (2). The present invention further provides an electrographic photosensitive member which comprises a substrate (1,5) and either a single layer (6) combining carrier transport and carrier generation functions or a separate carrier transport layer (2) and a carrier generation layer (3), characterised in that the photosensitive member is obtainable by the process of the present invention. The object and features of the present invention will become more readily apparent from the following detailed description of the preferred embodiments taken in conjunction with the accompanying drawings in which: Fig. 1 is a cross-sectional view of an electrophotographic photosensitive member according to a first embodiment of this invention; Fig. 2 is a cross-sectional view of an electrophotographic photosensitive member according to a second embodiment of this invention; Fig. 3 is a cross-sectional view of an electrophotographic photosensitive member according to a third embodiment of this invention; and Fig. 4-a, 4-b and 4-c are cross-sectional views of electrophotographic photosensitive members according to a fourth embodiment of this invention. Fig. 1 shows an embodiment of an electrophotographic photosensitive member according to the present invention. As shown in Fig. 1, the electrophotographic photosensitive member 10 comprises a substrate 1, a carrier transport layer 2, and a carrier generation layer 3. The carrier generation layer 3 has a free surface 4 at one side. Various metals such as aluminium are mainly used as the substrate 1. The carrier transport layer 2 comprises a polymer whose main component is a straight chain compound having p-phenylene, and having chalcogen element at para position, such as PPS (poly-p-phenylene sulfide). The carrier transport layer 2 is treated under conditions of a temperature between 250 and 350°C and a time between 0.2 to 50 hours, and more preferably, a temperature between 260 and 290°C and a time between 1 and 12 hours, in an atmosphere containing oxygen. In order to overcome the drawback that PPS film has a low carrier mobility and a short lifetime, various investigations have been carried out. As a result, by the treatment described above, it was clarified that the capacity for transporting carrier is largely improved. Moreover, it has been confirmed that the capacity for transporting carrier is not improved in an atmosphere of inert gas such as nitrogen or in a vacuum. Besides, it has been confirmed that oxygen atoms in the ratio O atoms to C atoms of from 1 to 35:100 by atom, and more preferably 1 to 20:100 are included in the treated carrier transport layer 2. The treated carrier transport layer 2 must satisfy the properties described above such as the capacity for accepting carrier, abrasion resistance, high photosensitivity and low residual electric potential which are required in the process of the electrophotography. The carrier transport layer 2 is hardened by the treatment described above, whereas the hardness of PPS film formed by a biaxial stretching method is very soft so that the hardness of the film cannot be exactly measured by a Micro Vickers hardness tester, when the treatment is not carried out. On the other hand, the Vickers hardness of the film treated as described above becomes 10 to 80. Owing to the fact that the heat resistance is increased and oxygen atoms, which increase the capacity for transporting carrier, are stably incorporated into the film, the electrophotographic photosensitive member 10 having a high sensitivity and a low residual electric potential can be produced. Moreover, the electrophotography photosensitive member 10 is stable even when making film by plasma or heating the substrate 1 so as to form the carrier generation layer 3 having a high capacity for generating carrier. As a result, the photosensitive member 10 having an excellent printing durability can be obtained without worsening the hardness of the entire photosensitive member, even when the carrier generation layer 3 which has a high capacity for generating carrier and has Vickers hardness of 100 or more is thinly formed on the PPS layer 2. A typical carrier generation layer 3 containing an inorganic material is a non-single crystal layer containing silicon having a large hardness. As the carrier generation layer 3, a single layer or a piled layer containing amorphous or non-single crystalline of a-Si (:H:X:), a-Si 1-y C y (:H:X) (0<y<1), a-Si 1-y O (:H:X) (0<y<1), a-Si 1-y N y (:H:X) (0<y<1), a-Si 1-z Ge z (:H:X) (0<z<1), a-(Si 1-z Ge z ) 1-y N y (:H:X) (0<y, z<1), a-(Si 1-z Ge z ) 1-y O y (:H:X) (0<y, z<1) or a-(Si 1-z Ge z ) 1-y C y (:H:X) (0<y, z<1) are used. In this case, these materials can be used even when "y" is successively varied. a-Si (:H:X) used in the carrier generation layer 3 containing silicon can be prepared by a plasma CVD method, using gas containing silicon such as SiH 4 , Si 2 H 6 , Si 3 H 8 , SiF 4 , SiCl 4 , SiHF 3 , SiH 2 F 2 , SiH 3 F, SiHCl 3 , SiH 2 Cl 2 , SiH 3 Cl and the like. Moreover, a-Si (:H:X) can be prepared by a reactive sputtering method in which polycrystal silicon is used as a target in a mixture gas of Ar and H 2 . In this case, the mixture gas can be mixed with F 2 or H 2 . a-Si 1-y C y (:H:X) (0<y<1), a-Si 1-y O y (:H:X) (0<y<1) or a-Si 1-y N y (:H:X) (0<y<1) can be prepared by the plasma sputtering method, using gas containing C atom, for example, hydrocarbon such as CH 4 , C 2 H 6 , C 3 H 8 , C 4 H 10 , C 2 H 4 , C 3 H 6 , C 4 H 8 , C 2 H 2 , C 3 H 4 , C 4 H 6 and the like, allyl halide such as CH 3 F, CH 3 Cl, CH 3 I, C 2 H 5 Cl,C 2 H 5 Br and the like, Freon gas such as CClF 3 , CF 4 , CHF 3 , C 2 F 6 , C 3 F 8 , and the like, fluorinated benzene such as C 6 H 6-m F m (m=1 to 6) as C source and the gas containing Si atom described above, and can be prepared by the reactive sputtering method, using the gas containing C,atom described above, sputtering gas such as Ar, and the silicon target described above. In this case, O 2 , CO, CO 2 , NO and NO 2 can be used as O source, and N 2 , NH 3 and NO can be used as O source as well. a-Si 1-z Ge z (:H:X) (0<z<1) can be prepared by the plasma CVD method, using the gas containing Si atom described above and gas containing Ge atom such as GeH 4 , Ge 2 H 6 , Ge 3 H 8 , GeF 4 , GeCl 4 , GeHF 3 , GeH 2 F 2 , GeH 3 F, GeHCl 3 , GeH 2 Cl 2 and the like. a-(Si 1-z Ge z ) 1-y N y (:H:X) (0<y, z<1), a-(Si 1-z Ge z ) 1-y O y (:H:X) (0<y, z<1) or a-(Si 1-z Ge z ) 1-y (:H:X) (0<y, z<1) can be prepared by the plasma CVD method, using the gas containing Ge atom described above, and a-Si 1-y C y (:H:X) (0(y(1), a-Si 1-y O y (:H:X) (0<y<1) or a-Si 1-y N y (:H:X) (0<y<1) respectively. Conductivity can be controlled by adding impurities to the film of a-Si (:H:X), a-Si 1-y C y (:H:X) (0<y<1), a-Si 1-y O y (:H:X) (0<y<1), a-Si 1-y O y (:H:X) (0<y<1) or Ge-added these materials. As a result, desirable electrophotography property can be obtained. As P-type impurities which afford P-type conductivity, there are elements of group of IIIb such as B, Al, Ga, In and the like. Preferably, B, Al and Ga are used. As N-type impurities which afford N-type conductivity, there are elements of group of Vb such as N, P, As, Sb and the like. Preferably, P and As are used. As a method for adding these impurities, in the case of P-type materials, gas such as B 2 H 6 , B 4 H 10 , B 5 H 11 , B 6 H 12 , B 6 H 14 , BF 3 , BCl 3 , BBr 3 , AlCl 3 , (CH 3 ) 3 Al, (i-C 4 H 9 ) 3 Al, (CH 3 ) 3 Ga, (C 2 H 5 ) 3 Ga, InCl 3 or such a gas diluted by H 2 , He or Ar is mixed with the gas containing C atom described above and the gas containing Si atom and the like described above when forming a film by the plasma CVD method. In the case of N-type materials, gas such as N 2 , NH 3 , NO, N 2 O, NO 2 , PH 3 , P 2 H 4 , PH 4 I, PF 3 , PF 5 , PCl 3 , PCl 5 , PBr 3 , PBr 5 , PI 3 , AsH 3 , AsF 3 , AsCl 3 , AsBr 3 , SbH 3 , SbF 3 , SbF 5 , SbCl 3 , SbCl 5 or such a gas diluted by H 2 , He or Ar is mixed with the gas containing C atom described above and the gas containing Si atom and the like described above when forming a film by the plasma CVD method. In the reactive sputtering method, this gas is mixed with the mixed gas of Ar and H 2 (the mixed gas may contain F 2 or Cl 2 ). These gases are treated by the generally used methods. These carrier generation layers 3 have a large hardness, and have Vickers hardness of 900 to 1200 when measured by a micro Vickers hardness tester. Amorphous layers such as As 2 Se 3 and the like containing chalcogen elements can be used as other inorganic carrier generation layer 3. The hardness of As 2 Se 3 varies depending on substrate heating temperature when depositing, and Vickers hardness is 100 to 120 when the substrate temperature is 60 to 120 °C. AsSeTe containing Te can be also used as the carrier generation layer 3 as a single layer or a piling layer thereof so as to afford a high sensitivity in the range of visible radiation or near infrared radiation. Besides, a layer where crystal powder of CdS or CdSe is bonded with resins can be also used. It is difficult to measure the hardness of the layer where the crystal having a capacity for transporting carrier containing chalcogen elements is bonded with resins. However, the hardness of the resulting layer described above is larger than the hardness of As 2 Se 3 film. On the other hand, the hardness of the straight chain compound polymer layer is measured for ascertaining the progress of the heat treatment. In this case, micro Vickers hardness tester is used, and the measurement is carried out under the condition that the load of the indenter of diamond is 10 g. On the other hand, as typical organic materials for the carrier generation layer 3, there are nonmetal phthalocyanine (H 2 Pc), metal phthalocyanine such as Cu-phthalocyanine (CuPc) or Mg-phthalocyanine (MgPc), halogenated metal phthalocyanine such as Indium phthalocyanine (InClPc), Aluminium phthalocyanine (AlClPc) or AlClPcCl, or TiOPc. These materials are formed into the carrier generation layer 3 by means of deposition and the like. The thickness of the carrier transport layer 2 is 5 to 50 micrometers, and preferably, 10 to 25 micrometers. The thickness of the carrier generation layer 3 is 0.05 to 10 micrometers, and preferably, 0.1 to 5 micrometers. Fig. 2 shows a second embodiment of the present invention for the electrophotographic photosensitive member 10. As shown in Fig. 2, the electrophotography photosensitive member 10 comprises a substrate 1, a carrier transport layer 2, and a carrier generation layer 3. This second embodiment is different from the first embodiment in that the carrier generation layer 3 is directly disposed on the substrate 1. Therefore, the carrier transport layer 2 has a free surface 4 at one side. The formation method of each of these layers is the same manner as that of first embodiment. The effect -of this embodiment is substantially equal to that of first embodiment as well. Moreover, in Fig. 1 showing the first embodiment, between the substrate 1 and the carrier transport layer 2, a barrier layer (not shown) can be provided which prevents carrier from being injected from the substrate 1 to the carrier transport layer 2, in order to improve the electrophotography property. In Fig. 2 showing the second embodiment, between the substrate 1 and the carrier generation layer 3, the barrier layer can be provided which prevents carrier from being injected from the substrate 1 to the carrier generation layer 3. This fact is applied to the third embodiment of Fig. 3 which will be described below. As materials used as the barrier layer, there are metallic oxides such as Al 2 O 3 , BaO, BaO 2 , BeO, Bi 2 O 3 , CaO, CeO 2 , Ce 2 O 3 , La 2 O 3 , Dy 2 O 3 , Lu 2 O 3 , Cr 2 O 3 , CuO, Cu 2 O, FeO, PbO, MgO, SrO, Ta 2 O 3 , ThO 2 , ZrO 2 , HfO 2 , TiO 2 , TiO, SiO 2 , GeO 2 , SiO, or GeO, metallic nitride such as TiN, AlN, SnN, NbN, TaN or GaN, metallic carbide such as WC, SnC or TiC, insulating material such as SiC, SiN, GeC, GeN, BC or BN, organic compound having heat resistance such as polyimide, poly-amide-imide or polyacrylonitrile. Fig. 3 shows the third embodiment of the present invention for the electrophotographic photosensitive member 10. As shown in Fig. 3, a photoconductive layer 6 a comprising a polymer such as PPS including pigment or inorganic carrier generation material such as CdS is provided on a substrate 5. The photoconductive layer 6 has a free surface 7 at one side. Inorganic carrier generation materials such as CdS, or organic pigments which are carrier generation materials such as phthalocyanine, having heat resistance are dispersed in a film such as PPS. By thermally bonding the film containing carrier generation material on the substrate 5, the photosensitive member 10 can be inexpensively produced. As pigments which are mixed with the film of PPS, phthalocyanine materials are used when preparing the photoconductive layer 6. As such pigments, there are nonmetal phthalocyanine (H 2 Pc), metal phthalocyanine such as Cu-phthalocyanine (CuPc) or Mg-phthalocyanine (MgPc), halogenated metal phthalocyanine such as Indium phthalocyanine (InClPc), Aluminium phthalocyanine (AlClPc) or AlClPcCl, or TiOPc. Moreover, as inorganic carrier generation materials which are mixed with the film such as PPS, there are CdS, CdSe and the like. When the photoconductive layer 6 is a single layer, the thickness of the film is 5 to 50 micrometers, and preferably, 10 to 25 micrometers. Besides, a surface covering layer 8 can be formed as shown in Fig. 4-a, 4-b and 4-c, so as to increase a cleaning property, abrasion resistance or corona resistance. As materials used as such surface covering layer, there are Si x O 1-x , Si x C 1-x , Si x N 1-x , Ge x O 1-x , Ge x C 1-x , Ge x N 1-x , B x N 1-x , B x C 1-x , Al x N 1-x (0<x<1), carbon, or such materials containing H 2 or halogen. Moreover, as organic compounds, there are polyimides, poly-amide-imides, polyacrylonitriles and the like. The following Examples illustrate the invention. Example-1 In this example, an electrophotographic photosensitive member 10 of the type as shown in Fig. 1 is produced. On quartz glass bases, PPS films having thickness of 12 and 25 micrometers are placed respectively, and then, stainless steel bases coated with Teflon as mold lubricant are placed on these films so as to weight. Thereafter, these films are treated under conditions of a temperature of 280°C and a time of 1 hour in an atmosphere of oxygen so that these films are thermally bonded on the quartz glass bases. Then, the hardness of these films are measured by a micro Vickers hardness tester. The hardness of the film having a thickness of 12 micrometers is 25±5 and the hardness of the film having a thickness of 25 micrometers is 15±5. Under these conditions, as shown in Fig. 1, PPS are thermally bonded on the aluminium substrate 1 so as to make the carrier transport layer 2. Next, the carrier generation layer 3 comprising As 2 Se 3 and having a thickness of about 0.8 micrometer is formed by means of a vacuum deposition method, with the substrate 1 being heated to 140°C. As a result, the electrophotographic photosensitive member 10 of this example is obtained. Thereafter, the electrophotographic photosensitive member 10, in which the thickness of PPS is 12 micrometer, is charged so that the surface potential of the photosensitive member 10 becomes +600V. When the photosensitive member 10 is exposed by the light of 500 nm, half value potential exposure is 0.5 lux·sec in the unit of illuminance. This value means extremely high sensitivity. Moreover, the residual potential is 90 or below. This value means excellent property. At this time, the electrophotographic photosensitive member 10, in which the thickness of PPS is 25 micrometers, has a high half value potential exposure of 0.71 lux·sec. However, the residual potential is slightly high such as 120 to 150 V. Example-2 In this example, an electrophotographic photosensitive member 10 of the type as shown in Fig. 4-a is produced. PPS having a thickness of 15 micrometers is thermally bonded with the aluminum substrate 1. It is treated under conditions of a temperature of 280°C and a time of 6 hours in an atmosphere of oxygen. The hardness of the PPS film 2 after treatment is 75±5. After the substrate 1 having the carrier transport layer 2 is placed at an anode side of a plane parallel plate typed capacity coupling method plasma CVD apparatus having a discharge electrode of (6 inches) 15cm. Then the air pressure within the chamber is reduced to 5x10 -6 torr, 1 torr = 1,33x10 -4 MPa, or below, and the substrate 1 is heated to a temperature between 150 and 200°C. The carrier generation layer 3 comprising a-Si:H is formed with 10 to 40 sccm of SiH 4 and 10 ppm of B 2 H 6 being introduced into the chamber under conditions of a pressure of 0.2 to 1.0 torr, 1 torr = 1,33x10 -4 MPa, and a high frequency electric power of 20 to 100 W. Moreover, a surface covering layer 8 having a thickness of 0.08 to 0.3 micrometers and comprising Si 1-x C x :H (0<x<1) is formed with 10 to 30 sccm of SiH 4 and 20 to 40 sccm of C 2 H 4 being introduced into the chamber under conditions of a pressure of 0.2 to 1.0 torr, 1 torr = 1,33x10 -4 MPa, and a high frequency electric power of 50 to 150 W. Thus, the electrophotographic photosensitive member 10 is made. The resulting photosensitive member 10 has an increased resistance against plasma. The photosensitive member 10 is charged so that the surface potential is 500 V and is exposed with white light. As a result, the photosensitive member 10 has a high sensitivity of 0.7 lux· sec and a residual potential of 100 V so that the photosensitive member 10 can be used practically. Besides, in the case that 0.02 to 0.1 wt% of TCNE (tetra cyano ethylene) as carrier accepting material is added to PPS layer 2, the electrophotographic photosensitive member 10 is produced which has a smaller residual potential such as 50 to 90 V. Example-3 In this example, an electrophotographic photosensitive member 10 of the type as shown in Fig. 1 is produced. A cylindrical PPS film having a thickness of 15 micrometers is prepared by an inflation method. The drawing magnification is 3 to 4 in the direction of the axis of the cylinder and is 2 to 2.5 in the direction perpendicular to the axis of the cylinder. And the diameter of the cylindrical film is 92 mm. In the process for making the electrophotographic photosensitive member 10, when an aluminium drum having a diameter of 92 mm is inserted into the above mentioned cylindrical film, and PPS film as the carrier transport layer 2 is formed by thermal contraction on the drum substrate 1, a thermal treatment is carried out in an atmosphere containing TCNQ (7, 7, 8, 8-tetra cyano quino di methane) as an electron acceptor. Moreover, the resulting film is treated under conditions of a temperature of 265°C and a time of 6 hours in an atmosphere of oxygen. Similarly, a film for measuring the hardness is treated as described above, and then, the hardness of the resulting film is measured with the film being bonded with a quartz base. The hardness of the film is 25±4. The drum described above is immersed in a solution containing CdS which is carrier generation powder and polyurethane resin as a binding resin. CdS and the binding resin are in the ratio 100:20 by weight. The carrier generation layer 3 having a thickness of 5 micrometers is formed with the immersed drum being dried under conditions of a temperature of 170°C and a time of 30 min. After the photosensitive drum obtained as described above is charged so that the surface potential becomes +600 V, the drum is exposed with white light. As a result, photosensitive drum is obtained whose half value potential exposure has a high photosensitivity such as 2.3 lux·sec and whose residual potential is sufficiently small such as 90 V or below. The electrophotographic photosensitive member 10 obtained as described above has a long lifetime such as a capability of printing eighty thousand sheets or more and is inexpensive. Example-4 In this example, an electrophotographic photosensitive member 10 of the type as shown in Fig. 3 or 4-c is produced. On an aluminium drum substrate 5 whose surface is polished, is placed a cylindrical PPS film containing 0.05 to 20 wt% of H 2 Pc and having a thickness of 20 micrometers or below where the diameter of the cylindrical PPS film is slightly smaller than that of the drum. In this case, the drum substrate 5 is cooled in a dried atmosphere so that the outer diameter of the drum becomes small by thermal contraction, and then, the cooled drum is inserted into the above mentioned PPS. Thereafter, the temperature of the drum is raised to the room temperature so that the drum substrate 5 is placed in contact with the film. As a result, drum shaped substrate 5 can be covered with the film having an uniform thickness as well. The resulting drum substrate 5 is treated under conditions of a temperature between 260 and 280°C and a time of 0.5 to 10 hours in an atmosphere of oxygen so as to carry out thermal bonding and thermal treatment. Thus, a photoconductive layer 6 is produced. A single layer type photosensitive member 10 comprising the photoconductive layer 6 as shown in Fig. 3 is discharged so that the potential becomes +900 V. When the photosensitive member 10 is exposed with white light, the half value potential exposure is 3.0 lux.sec or below. This value means a good photosensitivity. Besides, in the case that a surface covering layer 8 comprising polyimide and having a thickness of 0.2 micrometers is formed on the single layered photosensitive member 10 as shown in Fig. 4-c, the change of the surface potential is small even when the photosensitive member 10 is used repeatedly. Thus, the resulting photosensitive member 10 has a good property. Example-5 In this example, an electrophotographic photosensitive member 10 of the type as shown in Fig. 2 is produced. As shown in Fig. 2, on an aluminium drum substrate 1 whose surface is polished, a barrier layer (not shown) comprising Ge x N 1-x and having a thickness of 0.5 micrometers is formed. On the barrier layer, the carrier generation layer 3 comprising a-Si:H and having a thickness of 1 micrometer is formed. The resulting substrate 1 having the barrier layer and the carrier generation layer 3 is inserted into a cylindrical PPS film having a thickness of 25 micrometers or below whose diameter is slightly larger than that of the drum, and then, the entire is heated to a temperature between 100 to 150°C. At this time, PPS film is thermally contracted so that PPS film is placed in contact with the carrier generation layer 3. Thereafter, the resulting entire structure is heated to a temperature between 250 and 290°C in an atmosphere of oxygen so that the carrier transport layer 2 is formed. This drum photosensitive member 10 is negatively charged so that the surface potential becomes -500 to -800 V. Then, a clear image can be obtained. The half value potential exposure of this drum is 1 lux.sec. this value means a high photosensitivity. And the residual potential is -100 to -200 V. Moreover, when a- (Si 1-z Ge z ):H in which Ge is added to a-Si:H is used, the photosensitivity becomes still higher. Besides, at 2, 5 positions or 3, 4 positions of phenylene group, even when different substituents in place of H 2 are placed, the property does not largely change. Example-6 In this example, an electrophotographic photosensitive member 10 of the type as shown in Fig. 1 is produced. On quartz glass bases, PPS films having a thickness of 16 micrometers whose drawing magnification are changed are placed respectively, and then, stainless steel bases coated with Teflon as mold lubricant are placed on these films as weights so that the uniformity of these films is improved. PPS films are thermally bonded with the quartz bases under conditions of a temperature of 280°C and a time of 1 hour in an atmosphere of oxygen. The hardness of these films is measured by a micro Vickers hardness tester. The hardness of the film is 35±5 when the drawing magnification is 4.0 to 6.0 and the hardness of the film is 15± 5 when the drawing magnification is 1.5 to 2.0. Under these conditions described above, PPS films are thermally bonded with aluminium substrates 1 respectively so as to form the carrier transport layers 2. Next, the carrier generation layers 3 comprising Se and having a thickness of about 0.8 micrometers are formed by the vacuum deposition method. Thus, electrophotographic photosensitive members 10 are produced. The electrophotographic photosensitive member 10 whose carrier transport layer 2 comprises PPS having 4.0 to 6.0 of the drawing magnification is charged so that the surface potential becomes +600 V. When the photosensitive member 10 is exposed with 500 nm of light, the half value potential exposure is 1.3 lux·sec in the unit of illuminance. This value means extremely high photosensitivity. Moreover, the residual potential is 60 V or below. This value means an excellent property. The electrophotographic photosensitive member 10 whose carrier transport layer 2 comprises PPS having 1.5 to 2.0 of the drawing magnification is evaluated in the same manner as described above. As a result, although the half value potential exposure is as high as 1.5 lux-sec, a relatively high residual potential of 120 V is resulted.

Claims: A process for producing an electrophotographic photosensitive member (10) which comprises providing on a substrate (1,5) either a single layer (6) combining carrier transport and carrier generation functions or a separate carrier transport layer (2) and a carrier generation layer (3), characterised in that said single layer (6) or separate carrier transport layer (2) is a layer containing a straight chain compound polymer comprising as main component units of the formula in the main chain, wherein X is S, Se or Te, which has been treated at a temperature of from 250°C to 350°C for from 0.2 to 50 hours in an atmosphere containing oxygen to introduce oxygen atoms into said polymer such that the ratio of the number of oxygen atoms to the number of carbon atoms in said thermally treated straight chain compound polymer is from 1:100 to 35:100 and such that the layer comprising the thermally treated straight chain compound polymer has a Vickers hardness of 10 to 80. A process according to claim 1, wherein said thermal treatment is effected at 260°C to 290°C for from 1 to 12 hours. A process according to claim 1 or 2, wherein the layer comprising the thermally treated straight chain compound polymer further comprises an electron acceptor. A process according to any one of the preceding claims which further comprises forming a surface covering layer (8) on the resulting photosensitive member. A process according to any one of the preceding claims, wherein the layer containing the straight chain compound polymer is formed by applying to a substrate surface a film of the straight chain compound polymer produced by a biaxial stretching method so as to have a drawing magnification of 1.5 to 6.0 in at least one direction and carrying out the thermal treatment. A process according to any one of the preceding claims, which comprises providing on a substrate (1): (a) a carrier generation layer (3) for generating carrier by optical pumping; and (b) said layer containing said thermally treated straight chain compound polymer as a carrier transport layer (2) for transporting said carrier. A process according to claim 6, wherein said carrier generation layer (3) comprises a non-single crystal layer including a modification material for decreasing electron spin density and including atoms of at least one of Si and Ge. A process according to claim 6, wherein said carrier generation layer (3) comprises a non-single crystal layer including at least one chalcogen element. A process as claimed in claim 8 wherein said carrier generation layer (3) has a Vickers hardness of 100 or more at room temperature and is on said carrier transport layer (2). An electrophotographic photosensitive member which comprises a substrate (1,5) and either a single layer (6) combining carrier transport and carrier generation functions or a separate carrier transport layer (2) and a carrier generation layer (3), characterised in that the photosensitive member is obtainable by a process as defined in any one of claims 1 to 9.

Inventors: AKIYAMA KOJI, ONOMICHI KYOKO, SAKAHARA CHISATO, TAKIMOTO AKIO, TANAKA EIICHIRO, WATANABE MASANORI, AKIYAMA, KOJI, ONOMICHI, KYOKO, SAKAHARA, CHISATO, TAKIMOTO, AKIO, TANAKA, EIICHIRO, WATANABE, MASANORI
Applicants: MATSUSHITA ELECTRIC IND CO LTD, MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD.
Application year: 1988
Main classification: G03G5
IPC codes: G03G5