Positive charge type organic photoconductor

Abstract: A positive charge type organic photoconductor in which the surface of the photoconductor having a film thickness of from 10 to 30 µm and containing at least from 15 to 40% by weight of a phthalocyanine type photoconductive compound in a resin binder, is treated with a reactive monomer or oligomer capable of extinguishing ionic active and radical active parts.

Description: The present invention relates to a photoconductor used for an electrophotographic copying machine or printer. An electrophotographic copying machine or printer is repeatedly used many times by electrically charging the surface of a photoconductor, forming an electrostatic latent image by exposing to light, developing the electrostatic latent image with a toner to form a visible image, transferring the visible toner image onto a paper or the like, fixing the transferred toner image thereon, removing electricity from the photoconductor and cleaning the surface of the photoconductor. Thus, the electrophotographic photoconductor is required to have satisfactory electrophotographic properties including good charging properties and photosensitivity as well as satisfactorily small dark decay, and is also required to have satisfactory physical properties including good printing resistance, abrasion resistance and moisture resistance as well as good chemical resistance to ozone or the like generated during corona discharging. It is also required that the above-mentioned electrophotographic properties do not substantially change as a lapse of time during repeatedly using. Heretofore, inorganic photoconductors such as selenium, zinc oxide and cadmium sulfide were used as an electrophotographic photoconductive material. Recently, however, many organic photoconductors have often been used to solve the toxicity problem of the inorganic material, or to satisfy a high speed copying machine or printer which requires a light source producing a high luminance, or to comply with a shift of a photosensitive wavelength zone to a long-wavelength zone due to the use of a semiconductor laser or LED. Also, a positive charge type organic photoconductor which can control the generation of ozone during corona discharging to a much lower level, has attracted a good deal of public attention. The merit of using a phthalocyanine type photoconductive material as the positive charge type organic photoconductor is well known from U.S. Patent No. 3,816,118 and Japanese Examined Patent Publication No. 4338/1974. That is, the phthalocyanine type photoconductive compound generally has a high light-absorbance and excellent heat resistance, chemical resistance and light resistance, and also has a high photoconductivity by light exposure, i.e. excellent in the efficiency of generating an electron-hole pair. A positive charge type photoconductor using a phthalocyanine type compound is generally composed of an undercoat layer on an aluminum drum and a layer having the phthalocyanine type compound powder dispersed in resin coated thereon. Thus, the basic structure is very simple. The conventional positive charge type organic photoconductor using a phthalocyanine type photoconductive compound has such a structure as mentioned above, and the amount of ozone generated is small since the photoconductor is charged with positive corona, but the conventional photoconductor has a defect of being very poor in ozone resistance. Consequently, the life of the photoconductor is remarkably reduced by repeated use and by use under such conditions of high temperature and moisture as to highly generate ozone, and it is therefore necessary for practically using the conventional photoconductor to conduct aeration around the photoconductor in such a manner as to prevent the exposure or attack of ozone. The present invention has been made to completely solve the above mentioned ozone problems related to the conventional photoconductor. As a method for solving the above mentioned problems, it is easily conceived to provide an overcoat layer on a photoconductor in such a manner as to prevent the photoconductor from direct exposure to ozone atmosphere. It is disclosed in U.S. Patent No. 3,816,118 to provide an overcoat layer, but its main object is to provide such a physical protective layer for a photoconductor as to improve printing resistance, wear resistance and moisture resistance. The present inventors have recognised that such an overcoat layer is effective in this respect, but have recognized also that such an overcoat layer brings disadvantages on the other hand. That is, the photosensitivity of the photoconductor is lowered by the presence of the overcoat layer, and the photosensitivity varies as a lapse of time in proportion as the overcoat layer is mechanically abraded according to a printing resistance test. Moreover, it was discovered that the above-mentioned overcoat layer was not always effective for blocking ozone. That is, it was experimentally observed that ozone permeated through the overcoat layer to adversely affect on the properties of the photosensitive layer. JP-A-59135476 discloses a photosensitive element for electrophotography provided with a photosensitive layer comprising photoconductive powder (e.g. an azo pigment or a phthalocyanine pigment or the like) wherein pores in the outer surface of the photosensitive layer are eliminated by filling them with monomers (such as acrylic-, methacrylic, styrene- and vinyl-type monomers) which are then polymerized to seal the pores. The present inventors have fully studied the mechanism of the degradation of a photoconductor by ozone, and have found that the chemically defective part of the photoconductor is selectively attacked by ozone. The chemically defective part of the photoconductor means a structural defect of a phthalocyanine type compound used a photoconductive material, e.g. the state in which one atom of hydrogen is omitted, and a structural defect of a binder resin. These defective parts generally constitute ionic or radical active parts of long life, which are stable in normal stage. However, these defective parts tend to be decomposed easily by highly reactive ozone. If a photoconductor having no defect can be prepared, the ozone problem can be solved, but it is not practical for industrial use in respect of economics to prepare a photoconductor from a highly pure material having no defect. The present inventors have conducted the above-mentioned basic experiments and analyzed their data, and as this result, the present inventors have completed the present invention. According to a first aspect of the present invention, there is provided a positive charge type organic photoconductive layer in which the surface of the photoconductor having a film thickness of from 10 to 30µm and containing at least from 15 to 40% by weight of a phthalocyanine type photoconductive compound in a binder resin has been treated with a reactive oligomer, characterised in that said reactive oligomer is a phenol·novolak type epoxy resin or a mixture of a diglycidyl ether type epoxy resin of bisphenol A or bisphenol F with an amine type compound, and is capable of deactivating ionic active and radical active parts of said photoconductor, and in that said ionic active and radical active parts have been deactivated by said reactive oligomer. According to a second aspect of the present invention, the invention resides in the use of a reactive oligomer to deactivate ionic active and radical active parts of a photoconductor whereby to increase the ozone resistance of a positive charge type organic photoconductive layer in which the surface of the photoconductor having a film thickness of from 10 to 30µm and containing at least from 15 to 40% by weight of a phthalocyanine type photoconductive compound in a binder resin, has been treated with said reactive oligomer which is a phenol·novolak type epoxy resin or a mixture of a diglycidyl ether type epoxy resin of bisphenol A or bisphenol F with an amine type compound, and is capable of deactivating said ionic active and radical active parts. According to a third aspect of the present invention, there is provided a method of increasing the ozone resistance of a positive charge type organic photoconductor layer, comprising treating the surface of the photoconductor having a film thickness of from 10 to 30µm and containing at least from 15 to 40% by weight of a phthalocyanine type photoconductive compound in a binder resin with a reactive oligomer characterised in that the reactive oligomer is a phenol·novolak type epoxy resin or a mixture of a diglycidyl ether type epoxy resin of bisphenol A or bisphenol F with an amine type compound, and is used to deactivate ionic active and radical active parts of the photoconductor. In the drawings: Figure 1 shows charging properties; Figure 2 shows charge-retaining abilities; Figure 3 shows response speeds; Figure 4 shows spectrum sensitivities; Figure 5 shows repeated charging properties; Figure 6 shows light decay properties after repeating tests; Figure 7 shows environmental stabilities of dark decay properties; Figure 8 shows environmental stabilities of light decay properties; Figure 9 shows light fatigue properties; and Figure 10 shows light fatigue properties. Examples of phthalocyanine type photoconductive compounds which can be used in the present invention include those disclosed in the above-mentioned Japanese Examined Patent Publication No. 4338/1974. On account of the above-mentioned reasons, a phthalocyanine type material is preferably used in the positive charge type photoconductor of the present invention. Among the phthalocyanine type photoconductive compounds, χ type crystal of a metal-free phthalocyanine is preferably used. In the case of a metallophthalocyanine, the electrically neutral state is maintained ideally by coordinating phthalocyanine with metal, but a defective part is actually liable to occur and the defective part is easily oxidized by ozone. On the other hand, in the case of the metal-free phthalocyanine, only a small hydrogen atom is coordinated, and a coordination defect hardly occurs. The particle size of the phthalocyanine type photoconductive compound is preferably small so as to be satisfactorily dispersible. In the positive charge type photoconductor of the present invention, the above-mentioned phthalocyanine type compound is used generally in such a state as to be dispersed in a binder resin, and a binder resin having a good charge-retaining rate, which is a good dispersion medium for phthalocyanine, is used as it is in the present invention. However, in respect of ozone resistance, a binder resin which does not have ionic and radical active parts and which is insoluble or unswellable during the following treatment with the reactive oligomer, is preferably used. Preferable examples include thermosetting resins such as acrylic resin, polyester resin, urethane resin, butyral resin, and resins prepared by thermosetting these resins with amino resin, isocyanate resin or the like. It is necessary that the amount of the phthalocyanine type photoconductive compound contained in the photoconductor of the present invention should be from 15 to 40% by weight. This is the essential condition for enabling the photoconductor to work as a positive charge type photoconductor. If the amount of the photoconductive compound contained in the photoconductor is less than the above-mentioned range, the photosensitivity is remarkably lowered. On the other hand, if the amount of the photoconductive compound is larger than the above-mentioned range, the bulk resistance of the photoconductor is lowered and the charge-retaining ability is lowered. Thus, in order to obtain a good balance between the photosensitivity and the charge-retaining ability, it is preferable to use the photoconductive compound in an amount of from 25 to 35% by weight. A film thickness of the photoconductor should be in the range of from 10 to 30 µm. If the film thickness is thinner than this range, pinholes are liable to occur and mechanical properties such as printing resistance are remarkably lowered. On the other hand, if the film thickness is thicker than this range, a light response speed is lowered, and the amount of the expensive photoconductive material must be increased, thus being unpreferable from an economical viewpoint. Accordingly, the most preferable film thickness ranges from 15 to 25 µm in view of the charge-retaining ability and the light response speed. The photoconductor having the above mentioned film thickness is formed by mixing a phthalocyanine type photoconductive material with a binder resin and a solvent, dispersing the mixture by means of a paint shaker, a ballmil, a dispersing machine or the like, and coating the resultant dispersion on an undercoat layer provided on the surface of an aluminum drum by a dipping method, a spray method or the like. There are necessarily present an ionic active part and a radical active part which are closely related with ozone resistance on the surface of the photoconductor containing the above-mentioned phthalocyanine type photoconductive compound. The ionic active part and the radical active part mean the type of chemical groups including a coordination defect of phthalocyanine and a relatively stable radical in a binder resin such as an aryl radical, which are stable under such normal conditions as mentioned above, but are easily deteriorated by being attacked by a highly reactive molecule (a strong oxidizer) such as ozone. According to the present invention, these active parts are extinguished in advance by treating with said reactive oligomer. Examples of the above-mentioned reactive oligomer which can be polymerized by radical reaction are disclosed in Japanese Unexamined Patent Publications Nos. 139832/1976 and 75235/1978, and examples of reactive oligomer which can be polymerized by ion polymerization reaction are disclosed in Japanese Unexamined Patent Publication No. 83966/1979. Among the above-mentioned reactive oligomers, diglycidylether type epoxy resins of bisphenol A or bisphenol F which have been satisfactorily used as an electrical insulating material, are preferably used in the present invention from the viewpoints of ozone resistance, charge-retaining ability and photosensitivity, and as a curing agent, a highly reactive (first-curing) amine type compound is preferably used. It is naturally preferable to use these compounds in a stoichiometric ratio. A method for treating the photoconductive layer with the reactive oligomer is not specially limited so long as it extinguishes the active parts as mentioned above. For example, one method comprises dissolving the above mentioned reactive oligomer in an organic solvent, dipping the photoconductor into the low viscosity solution thus prepared, drying the solvent and then reacting. It is preferable to use a solution having a low concentration of not higher than 5% in such a manner that the same inconveniences as in the above-mentioned conventional overcoat layer will not occur. It is also preferable not to prolong the dipping time so long in order that the reactive oligomer will not impregnate into the photoconductive layer to prevent the photosensitivity from lowering. It is also preferable to use such an organic solvent as not-to swell or dissolve the binder resin of the photoconductive layer. The present invention is further illustrated in more details by the following Examples but should not be limited thereto. EXAMPLES 1 TO 14 A substrate for a photoconductive layer was prepared by dipping a polished aluminum plate in a methanol solution of a polyamide resin ("CM-8000" manufactured by Toray K.K.) to form an undercoat layer and drying. The average film thickness was about 0.5 µm. Mixture solutions were prepared by using the following phthalocyanine type photoconductive compounds and binder resins in such a manner as shown in Table 1 and using cyclohexanone, methyl ethyl ketone, toluene and xylene respectively alone or in a mixture as a dispersion solvent depending on the solubility of the binder resin employed. Phthalocyanine type photoconductive compounds: (A) χ type crystal of metal-free phthalocyanine ("8120B" manufactured by Dainihon Ink Kagaku Kogyo K.K.), (B) ε type crystal of copper phthalocyanine ("EP-101" manufactured by Dainihon Ink Kagaku Kogyo K.K.), (C) β type crystal of copper phthalocyanine ("4920" manufactured by Dainichi Seika Kogyo K.K.), and (D) α type crystal of copper phthalocyanine ("B" manufactured by Toyo Ink Seizo K.K.). Binder resins: (a) Epoxy resin ("Epikote® 828" and "Epomate® B-002" (50 phr) manufactured by Yuka Shell Epoxy K.K.), (b) Polycarbonate resin ("PCZ-4000" manufactured by Mitsubishi Gas Kagaku K.K.), (c) Melamine/acrylic resin blend ("11-30" manufactured by Fuji Shikiso K.K.), (d) Styrene-acrylic resin ("CPR-100" manufactured by Mitsui Toatsu Kagaku K.K.), (e) Polyester/melamine resin blend (127/32 weight ratio blend of "P-645" (manufactured by Mitsui Toatsu Kagaku K.K.)/"Uban20-HS®" (manufactured by Mitsui Toatsu Kagaku K.K.)), (f) Silicone resin (100/10 weight ratio blend of "KE-108" manufactured by Shinetsu Silicone K.K.)/"CAT-108" manufactured by Shinetsu Silicone K.K.)), (g) Polyurethane resin ("8-30" manufactured by Fuji Shikiso K.K.), and (h) Vinylchloride·vinylacetate copolymer ("9-30" manufactured by Fuji Shikiso K.K.). The above mixture solutions were prepared by blending a phthalocyanine type photoconductive compound in an amount of from 25 to 35% by weight, adjusting to give a solid content of from 15 to 30% by weight and dispersing the resultant mixture by a paint shaker (manufactured by Reddevil Company) from 15 minutes to 2 hours. The mixture solution thus prepared was coated on the above prepared substrate having the undercoat layer by dipping method to form a photoconductive layer. The coating was conducted by dipping the substrate in the mixture solution for 2 minutes at a pulling up rate of not higher than 100 cm/minute, preferably from 15 to 20 cm/minute. The samples thus coated were dried at room temperature for overnight, and were heated in an oven at 150°C for 4 hours to obtain semi-photoconductor test pieces Nos. 1 to 14. The compositions and the film thicknesses of the semi-photoconductors thus obtained are shown in Table 1. Electrophotographic properties including ozone resistance of the semi-photoconductor test pieces Nos. 1 to 14 thus obtained were evaluated by measuring initial charge potentials V 0 (V), charge potentials V 30 (V) after continuously corona charging for 30 seconds and charge potentials V 90 (V) after continuously corona charging for additional 1 minute of the semi-photoconductors charged at a constant current of +10 µA by means of "EPA-8100" manufactured by Kawaguchi Denki Seisakusho. If a semi-photoconductor is excellent in ozone resistance, the charge potential does not vary between the V 0 value and the V 90 value, but if a semi-photoconductor is poor in ozone resistance, the V 90 value is largely lowered than the V 0 value. The measurement results are shown in Table 2. Thereafter, 50 phr of amine ("Epomate® B-002" manufactured by Yuka Shell Epoxy K.K.) was added to diglycidyl ether type epoxy resin of bisphenol F ("Epikote® 815" manufactured by Yuka Shell Epoxy K.K.), and the resultant mixture was dissolved in ethanol to prepare a 0.5% solution. The above prepared semi-photoconductor test pieces Nos. 1 to 14 were dipped in this solution for 1 minute, and were then dried in air for 2 hours and were heated in an oven at 120°C for 2 hours to prepare photoconductor test pieces. The increase in the film thickness of every test piece by this treatment was not more than 1 µm. The electrophotographic properties including ozone resistance of the photoconductor test pieces (Examples 1 to 14) thus obtained were measured in the same manner as above, and the results are shown in Table 3. As evident from Table 3, all of the photoconductors of Examples 1 to 14 of the present invention were excellent in ozone resistance. Thus, the ozone resistance of a photoconductor was greatly improved by treating with epoxy resin (reactive oligomer). Semi-photosensitive material test piece No. Photoconductive compound Binder resin Content of photoconductive compound (%) Film thickness (µm) 1 (A) (d) 30 20 2 (B) (d) 30 20 3 (C) (d) 30 20 4 (D) (d) 30 20 5 (A) (b) 30 20 6 (A) (c) 30 20 7 (A) (e) 30 20 8 (A) (f) 30 20 9 (A) (g) 30 20 10 (A) (h) 30 20 11 (A) (e) 25 20 12 (A) (e) 35 20 13 (A) (e) 30 15 14 (A) (e) 30 25 Semi-photosensitive material test piece No. V 0 (V) V 30 (V) V 90 (V) Measurement temperature and moisture (°C) (%) 1 566 422 363 19.0 40 2 610 380 250 19.0 40 3 670 370 210 19.0 40 4 610 300 170 19.0 40 5 383 218 193 19.6 43 6 765 420 365 20.0 38 7 600 450 340 14.2 45 8 511 31 24 19.7 43 9 543 186 78 19.7 42 10 254 72 48 18.6 51 11 675 408 373 20.0 38 12 408 227 180 20.0 38 13 560 430 300 21.5 42 14 630 480 390 21.5 42 Example No. Semi-photosensitive material test piece No. V 0 (V) V 30 (V) V 90 (V) Measurement temperature and moisture (°C) (%) 1 1 561 525 511 19.0 40 2 2 619 601 583 19.0 40 3 3 706 675 652 19.0 40 4 4 618 596 581 19.0 40 5 5 400 390 390 19.6 43 6 6 759 698 671 20.0 38 7 7 650 620 540 14.2 45 8 8 525 453 382 19.7 43 9 9 545 500 460 19.7 42 10 10 271 270 270 18.6 51 11 11 673 634 610 20.0 38 12 12 415 410 410 20.0 38 13 13 564 531 526 21.5 42 14 14 655 620 597 21.5 42 EXAMPLES 15 TO 16 Photoconductor test pieces were prepared in the same manner as in Example 7, except that bisphenol F type epoxy resin was replaced by bisphenol A type epoxy resin ("Epicote® 828" manufactured by Yuka Shell Epoxy K.K.) (Example 17) or by phenol·novolak type epoxy resin ("Epikote® 152" manufactured by Yuka Shell Epoxy K.K.) (Example 18), and were evaluated with regard to the electrophotographic properties in the same manner as above. The results are shown in Table 4. COMPARATIVE EXAMPLES 1 TO 3 As Comparative Examples, comparative test pieces were prepared by forming an overcoat layer of polyester ("P-645" manufactured by Mitsui Toatsu Kagaku K.K.) (Comparative Example 1), butyral resin ("Esrec® B" manufactured by Sekisui Kagaku Kogyo K.K.) (Comparative Example 2) or polycarbonate ("PCZ-4000" manufactured by Mitsubishi Gas Kagaku K.K.) (Comparative Example 3) on the surface of the above prepared semi-photoconductor test piece No. 7 by usual coating method without using the reactive oligomer, and were evaluated with regard to the electrophotographic properties in the same manner as above. The results are shown in Table 4. As evident from the results of Table 4, the photoconductor prepared by treating with the reactive oligomer capable of extinguishing the ionic active and radical active parts are excellent in ozone resistance. On the other hand, as evident from Comparative Examples 1 to 3, the conventional overcoat layers do not achieve the effect for improving ozone resistance. Example No. V 0 (V) V 30 (V) V 90 (V) Measurement temperature and moisture (°C) (%) 15 670 645 590 18.7 42 16 650 595 490 18.7 42 Comparative Example 1 700 560 390 18.7 42 Comparative Example 2 760 680 420 18.7 42 Comparative Example 3 800 650 410 18.7 42 EXAMPLE 17 A photoconductive drum of 120 mm was prepared by using the same materials and method as in Example 7, and the photoconductive drum thus prepared was evaluated under such conditions has disclosed in Table 5 with regard to the electrophotographic properties, i.e. charging property (Figure 1), charge-retaining ability (Figure 2), response speed (Figure 3), spectrum sensitivity (Figure 4), repeated charging property (Figure 5), light decay property after repeating test (Figure 6), environmental stability of dark decay property (Figure 7), environmental stability of light decay property (Figure 8) and light fatigue property (Figures 9 and 10). The results are shown in Figures 1 to 10. Charging property (Figure 1) Temperature 26.1°C, Moisture 65% Charging-retaining ability (Figure 2) Temperature 19.4°C, Moisture 78% Response speed (Figure 3) Wavelength 780 nm, Exposure time 1/15 sec., Exposure amount 2 µJ/cm 2 Repeated charging property (Figure 5) Exposure 780 nm, 2 µJ/cm 2 Removal of electricity 650 nm, 4 µW/cm 2 × 1s = 4 µJ/cm 2 Since the measurement can not be conducted over 3,000 times per day, the measurement was conducted for 4 days. The marks, ·, ○, Δ and × respectively show the measurement results of the 1st, 2nd, 3rd and 4th day. Light response property after repeated tests (Figure 6) Exposure 780 nm, 2 µJ/cm 2 Removal of electricity 650 nm, 4 µW/cm 2 × 1s = 4 µJ/cm 2 Light fatigue property (Figure 9) Allowed to stand in a room of 700 lux Light fatigue property (Figure 10) Charging +5.0 µA As evident from the results of Figures 1 to 10, it is clear that the positive charge type organic photoconductor of the present invention is practically excellent. As mentioned above, the positive charge type organic photoconductor of the present invention uses a phthalocyanine type compound excellent in light absorbance, heat resistance, chemical resistance and light resistance and also excellent in production efficiency of electron·hole pair, and has an excellent ozone resistance.

Claims: A positive charge type organic photoconductive layer in which the surface of the photoconductor having a film thickness of from 10 to 30µm and containing at least from 15 to 40% by weight of a phthalocyanine type photoconductive compound in a binder resin has been treated with a reactive oligomer, characterised in that said reactive oligomer is a phenol·novolak type epoxy resin or a mixture of a diglycidyl ether type epoxy resin of bisphenol A or bisphenol F with an amine type compound, and is capable of deactivating ionic active and radical active parts of said photoconductor, and in that said ionic active and radical active parts have been deactivated by said reactive oligomer. A photoconductor according to claim 1, wherein the phthalocyanine type photoconductor compound is a χ type crystal of a metal-free phthalocyanine. A photoconductor according to claim 1, wherein the phthalocyanine type photoconductive compound is at least one (metallo)phthalocyanine selected from the group consisting of an ε type crystal copper phthalocyanine, a β type crystal copper phthalocyanine and an a type crystal copper phthalocyanine. A photoconductor according to any preceding claim, wherein the phthalocyanine type photoconductive compound is present in an amount of from 25 to 36% by weight. A photoconductor according to any preceding claim, wherein the film thickness of the photoconductive layer is from 15 to 25µm. A photoconductor according to any preceding claim, wherein the binder resin is at least one member selected from epoxy resins, polycarbonate resins, acrylic resins, melamine/acrylic resin blends, styrene·acrylic resins, polyester resins, polyester/melamine resin blends, silicone resins, polyurethane resins, butyral resins, vinylchloride·vinylacetate copolymers, amino resin-thermoset amino resins and thermoset isocyanate resins. A photoconductor according to any preceding claim, wherein the ionic active and radical active parts are at least one of a coordination defect of the phthalocyanine type photoconductive compound and a radical of the binder resin. A photoconductor according to any preceding claim, in the form of a coating on a drum-like substrate. The use of a reactive oligomer to deactivate ionic active and radical active parts of a photoconductor whereby to increase the ozone resistance of a positive charge type organic photoconductive layer in which the surface of the photoconductor having a film thickness of from 10 to 30µm and containing at least from 15 to 40% by weight of a phthalocyanine type photoconductive compound in a binder resin, has been treated with said reactive oligomer which is a phenol·novolak type epoxy resin or a mixture of a diglycidyl ether type epoxy resin of bisphenol A or bisphenol F with an amine type compound, and which is capable of deactivating said ionic active and radical active parts. A method of increasing the ozone resistance of a positive charge type organic photoconductor layer, comprising treating the surface of the photoconductor having a film thickness of from 10 to 30µm and containing at least from 15 to 40% by weight of a phthalocyanine type photoconductive compound in a binder resin with a reactive oligomer characterised in that the reactive oligomer is a phenol·novolak type epoxy resin or a mixture of a diglycidyl ether type epoxy resin of bisphenol A or bisphenol F with an amine type compound, and in that it is used to deactivate ionic active and radical active parts of the photoconductor.

Inventors: HAYAMA KIKUO, KOBAYASHI TOSHIO, TSUDA SHIGEO, TSUNODA SEI, YAMADA HIROMI, HAYAMA, KIKUO, KOBAYASHI, TOSHIO, TSUDA, SHIGEO, TSUNODA, SEI, YAMADA, HIROMI, HAYAMA, KIKUO, MITSUBISHI DENKI K. K., KOBAYASHI, TOSHIO, MITSUBISHI DENKI K. K., TSUDA, SHIGEO, MITSUBISHI DENKI K. K., TSUNODA, SEI, MITSUBISHI DENKI KABUSHIKI KAISHA, YAMADA, HIROMI, MITSUBISHI DENKI K. K.
Applicants: MITSUBISHI ELECTRIC CORP, MITSUBISHI DENKI KABUSHIKI KAISHA
Application year: 1992
Main classification: G03G5
IPC codes: C09B67, G03G5