EP1222964B1 - Liquid spray-coating method and electrophotographic photoreceptor formed by the method - Google Patents

Liquid spray-coating method and electrophotographic photoreceptor formed by the method Download PDF

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Publication number
EP1222964B1
EP1222964B1 EP20020000602 EP02000602A EP1222964B1 EP 1222964 B1 EP1222964 B1 EP 1222964B1 EP 20020000602 EP20020000602 EP 20020000602 EP 02000602 A EP02000602 A EP 02000602A EP 1222964 B1 EP1222964 B1 EP 1222964B1
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EP
European Patent Office
Prior art keywords
liquid
spray
supplier
coating device
spraying
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EP20020000602
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German (de)
English (en)
French (fr)
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EP1222964A1 (en
Inventor
Ryohichi Kitajima
Hiroshi Ikuno
Akihiko Matsuyama
Narihito Kojima
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Ricoh Co Ltd
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Ricoh Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C—APPARATUS FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05C11/00—Component parts, details or accessories not specifically provided for in groups B05C1/00 - B05C9/00
    • B05C11/10—Storage, supply or control of liquid or other fluent material; Recovery of excess liquid or other fluent material
    • B05C11/1047—Apparatus or installations for supplying liquid or other fluent material comprising a buffer container or an accumulator between the supply source and the applicator
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
    • B05B9/00—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour
    • B05B9/03—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour characterised by means for supplying liquid or other fluent material
    • B05B9/04—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour characterised by means for supplying liquid or other fluent material with pressurised or compressible container; with pump
    • B05B9/0403—Spraying apparatus for discharge of liquids or other fluent material, without essentially mixing with gas or vapour characterised by means for supplying liquid or other fluent material with pressurised or compressible container; with pump with pumps for liquids or other fluent material

Definitions

  • the present invention relates to a liquid spray-coating apparatus, to a liquid spray-coating method, and to an electrophotographic photoreceptor formed by the method which can be widely used for electrophotographic applications such as copiers, laser beam printers, CRT printers and photoengraving systems (see, for example, US-A-3 815 822 , corresponding to the preambles of independent product claim 1 and independent method claim 4).
  • inorganic photoconductive materials such as selenium and zinc oxide have been used for photosensitive layers of electrophotographic photoreceptors.
  • One layer is a charge generation layer absorbing light and generating a charge carrier, and the other is a charge transport layer transporting the charge carrier.
  • the functionally separated photoreceptor comprises a combination of an organic compound efficiently generating charge and an organic compound efficiently transporting the charge.
  • the photoreceptor has high sensitivity and is in practical use.
  • photoreceptors such as a photoreceptor having an undercoat layer between the electroconductive substrate and the photosensitive layer and a photoreceptor having a protective layer on the photosensitive layer have been invented.
  • photoreceptors having high chargeability, preventing moire and image deformation, and having high durability and environmental resistance have been invented by providing undercoat layers and protective layers having a thickness of from submicrons to a few microns and including fine particles, either organic or inorganic, uniformly dispersed in the layers on the photoreceptors.
  • Such layers are typically coated on a cylindrical drum substrate or an endless belt-shaped substrate, etc. to form organic photoreceptors.
  • coating methods a dip coating method, a spray coating method, a nozzle coating method, etc. are known.
  • the dip coating method is industrially used most and has been subject of extensive research.
  • the method has a disadvantage that much coating liquid is consumed when coating an endless belt-shaped substrate which has a large diameter and a cylindrical drum substrate which is long in many cases.
  • a low molecular-weight compound in a layer previously coated on a substrate tends to be dissolved out when coating a functionally separated photoreceptor because of dipping the substrate into the coating liquid and drawing up the substrate therefrom, resulting in quality deterioration of the resultant photoreceptor.
  • the compound dissolved out in the coating liquid often contaminates the coating liquid and largely affects the coating method.
  • the nozzle coating method is advantageous for coating an endless belt-shaped substrate which has a large diameter and a cylindrical drum substrate which is long in many cases because the consumption of the coating liquid is small.
  • a part of the substrate doubly coated at the beginning and the end of coating becomes thick, and technical difficulty to solve the problem is high.
  • the method is not suitable for industrial use because mechanical precision required for the coating apparatus is unrealistically high.
  • the spray coating method isialso advantageous for coating an endless belt-shaped substrate which has a large diameter and a cylindrical drum substrate which is long in many cases because the consumption of the coating liquid is small. Further, the method does not have the problem of thickening a part of the substrate doubly coated at the beginning and the end of coating, and is industrially used on occasion.
  • the method is advantageous for coating a protective layer on a functionally separated photoreceptor having a charge transport layer on the charge generation layer.
  • the coating liquid is a fine-particle dispersion liquid including at least a solvent and fine particles
  • the fine particles tend to sink in the spray coating apparatus and clog the spray gun when the spraying is stopped, resulting in deterioration of stable coating and coating irregularity.
  • Japanese Laid-Open Patent Publication No. 9-75794 discloses an air spray coating method and an apparatus supplying and transporting a coating liquid without retaining the liquid in the spray coating apparatus (a spray gun).
  • Japanese Laid-Open Patent Publication No. 58-174264 discloses a spray coating apparatus circulating a coating liquid.
  • the apparatus has the following circulation routes:
  • a syringe pump capable of precisely transporting small flow rate of the liquid to the spray coating device is used as a fine-particle dispersion-liquid supplier instead of liquid suppliers liable to bring pulsation such as a diaphragm pump and a gear pump, the dispersion liquid is retained in the cylinder and the sedimentation of the fine particles tends to go on because it is effective on production efficiency to stop the syringe pump as well when the spraying is stopped. Further, there also is a case where the rheology of the liquid changes.
  • liquid capacity (cylinder capacity) of the liquid supplier is far larger than that of the spray coating device, the adverse effect of the fine-particle sedimentation in the liquid supplier is more serious than that in the spray coating device.
  • an object of the present invention is to provide a coating method and a coating apparatus capable of forming a coated layer having a uniform composition.
  • Another object of the present invention is to provide a coating method and a coating apparatus capable of forming a coated layer having a uniform composition without a clogging of the spray coating device when the coating liquid is a liquid dispersing fine particles.
  • a method and an apparatus forming a coated layer having a uniform composition are provided, by a circulation-type spray coating method in which the liquid constantly flows in the liquid supplier, the spray coating device and the liquid feeding route when the spraying is stopped to prevent the heterogeneous liquid composition.
  • Yet another object of the present invention is to provide an electrophotographic photoreceptor having a layer including a uniform composition using the above-mentioned method and apparatus.
  • a method for manufacturing an electrophotographic photoreceptor using a circulation-type spray coating apparatus including at least a liquid supplier, a spray coating device atomizing and spraying the liquid, a liquid feeding route in which the liquid is transported from a liquid tank through the liquid supplier to the spray coating device, a liquid circulating route in which the liquid returns to the liquid tank from the spray coating device and a liquid pressurizer, wherein the liquid constantly flows in the liquid supplier, the spray coating device and the liquid feeding route.
  • the present invention provides a manufacturing method and an apparatus preferably used for coating such a liquid as loses its homogeneity due to the retention, particularly the method and the apparatus are preferably used for spray coating of a fine-particle dispersion liquid.
  • the method and the apparatus of the present invention prevent the spray gun from clogging, and equalize the content ratio of the fine particles of the solid content included in the dispersion liquid and that of the formed dispersed layer.
  • the method and the apparatus can form a thin and uniform coated layer having a thickness of from about submicrons to some ⁇ m.
  • the manufacturing method and the apparatus of the present invention are particularly suitable for forming a photosensitive layer of an electrophotographic photoreceptor.
  • the present invention is not limited hereto, and applicable for the fields besides the electrophotographies.
  • a fine-particle dispersion liquid is used as a coating liquid
  • the present invention is not limited to this case.
  • the fine-particle dispersion liquid dye-solution liquids, resin-solution liquids, emulsion liquids and the like liquids can be used as the coating liquids.
  • a syringe pump is used as the liquid supplier for use in the present invention.
  • the syringe pump includes at least a cylinder, a piston rod having a piston member capable of being freely inserted into the cylinder and a means of driving the piston rod, and precisely supplies a small flow rate of the liquid to the above-mentioned spray coating device by driving the piston rod when the spraying is performed.
  • the syringe pump has a liquid-flow duct in the cylinder or in the piston rod.
  • the piston rod includes the liquid-flow duct; a syringe pump is used, having a piston rod including at least an entrance and an exit for the liquid circulation, and the liquid-flow duct, in which the fine-particle dispersion liquid can constantly flow without staying in the cylinder when the spraying is stopped.
  • the spray coating device for use in the present invention is an air spray gun including at least a coating nozzle and an air cap, in which the pressure-fed liquid to the coating nozzle is atomized by compressed air discharge from the air cap.
  • the coating nozzle has at least a liquid-feed opening and an exit opening for the liquid circulation besides a discharge opening for the atomized liquid, and the liquid can constantly flow without staying in the spray gun when the spraying is stopped.
  • the liquid feeding and circulating route of the present invention including a liquid feeding route in which the liquid is transported to the spray coating device through the liquid supplier from a liquid tank; a circulating route in which the liquid returns to the liquid tank from the spray coating device; and a pressurizer for circulating the liquid
  • the liquid feeding route between the liquid tank and the liquid supplier and the circulating route between the spray coating device and the liquid tank respectively have one liquid-pressure blocker or more which blocks the liquid pressure given by the pressurizer.
  • the circulation is stopped by blocking the liquid pressure when the spraying is performed, the liquid pressure between the liquid supplier and the spray coating device is separated from the liquid pressure given by the pressurizer and equals the pressure given by the liquid supplier.
  • the liquid feeding and circulating route of the present invention can spray by the pressure of the liquid supplier.
  • the liquid supplier mainly gives the discharging pressure of the spray coating device
  • the pressurizer for circulation mainly controls the liquid circulation of the whole coating apparatus.
  • the liquid supplier is located between the pressurizer for circulation and the spray coating device.
  • the Fa is preferably from 300 to 1,500 cc/min, and the Fb is preferably from 5 to 100 cc/min.
  • Fig. 1 is a schematic view illustrating an outline of the method for manufacturing an electrophotographic photoreceptor in the present invention.
  • a fine-particle dispersion liquid 2 put and agitated in a coating liquid tank 1 is transported by the pressure of a pressurizer for circulation 3 to a liquid supplier 6 and a spray coating device 7 through a liquid feeding route 4, and then returned to the coating liquid tank 1 through a circulation route 8.
  • liquid-pressure blockers 5 located in the liquid feeding route 4 and the circulation route 8 are disengaged.
  • gear pumps, diaphragm pumps and the like pumps are preferably used, which can give sufficient flow rate to prevent the sedimentation of the fine particles.
  • Fig. 2 is a schematic view illustrating an embodiment of the liquid supplier of the present invention.
  • the liquid supplier is a syringe pump including a cylinder 11; a piston member 17; and a piston rod 12, and the piston rod 12 includes a circulation-liquid entrance 14, a circulation-liquid exit 15 and a circulation-liquid flow duct 16.
  • the fine-particle dispersion liquid 2 pressurized by the pressurizer for circulation 3 in Fig. 1 enters the circulation-liquid entrance 14 of the piston rod 12 connected to the liquid feeding route 4 and is supplied inside the cylinder 11 from the circulation-liquid exit 15 through the circulation-liquid flow duct 16 penetrating the piston rod 12.
  • the fine-particle dispersion liquid 2 is transported to the spray coating device 7 through the liquid feeding route 4 connected to the upper part of the cylinder.
  • the liquid supplier 6 stops as well and the piston rod 12 stays waiting in the bottom dead center.
  • the capacity of the cylinder 11 is preferably larger than the quantity of the dispersion liquid required for spray coating at a time.
  • the capacity which is larger than necessary is not preferable because of being a cause of deteriorating the preciseness of the liquid feeding when the spraying is performed.
  • the fine-particle dispersion liquid 2 can flow without staying in the cylinder 11 when the spraying is stopped. Therefore, the pressurizer for circulation 3 can give a liquid pressure such that sufficient circulating flow-rate can be obtained, regardless of the strength of the liquid pressure for spray coating. In addition, the sedimentation of the fine particles in the spray coating device 7 and the cylinder 11 can be prevented.
  • the circulating direction of the fine-particle dispersion liquid 2 is not limited thereto.
  • the liquid feeding route 4 from the pressurizer for circulation 3 may be connected to the upper part of the cylinder, and the fine-particle dispersion liquid 2 may be supplied inside the cylinder 11 through the route and transported to the spray coating device 7 through the circulation-liquid flow duct 16 penetrating the piston rod 12 after filling the inside of the cylinder 11.
  • the numeral 15 is a circulation-liquid entrance
  • the numeral 14 is an exit.
  • Fig 3 . and Fig. 4 are schematic views illustrating other embodiments of the liquid supplier of the present invention.
  • Fig. 3 is an example in which circulation-liquid flow ducts are formed inside a piston rod 12 and a piston member 17, which enable the liquid to flow uniformly inside the cylinder when the spraying is stopped.
  • Fig. 4 shows three examples in which circulation-liquid entrances 14 are formed on the wall of cylinders 11.
  • a in Fig. 4 is an example in which the liquid entrance is formed in the top dead center
  • B in Fig. 4 is an example in which the entrance is formed in the bottom dead center
  • C in Fig. 4 shows an example in which plural entrances are formed. The plural entrances are preferable for uniformity of the liquid flow inside the cylinder when the spraying is stopped.
  • Fig. 5 is a schematic view illustrating an embodiment of the spray coating device of the present invention.
  • the fine-particle dispersion liquid 2 is supplied to the coating nozzle 21 through the liquid feeding route 4 connected to a liquid-feed opening 24. Then the dispersion liquid 2 fills the inside of the coating nozzle 21, and returns to the coating liquid tank 1 through the circulation route 8 connected to a circulation exit 25.
  • the coating nozzle 21 may be a single piece with a spray gun 27, or may be detachably equipped with the spray gun 27 by a threaded type method.
  • the needle valve 26 is preferably structured such that the liquid leak is prevented by a gasket (not shown) at the rear end of the coating nozzle (the opposite side of the atomized-liquid discharger 23).
  • the liquid supplier 6 and the spray coating device 7 become independent of the circulating system.
  • the preferable operation order of the one or more liquid-pressure blockers 5 such as valves located on the liquid feeding route 4 and the circulation route 8 respectively is as follows:
  • the liquid-pressure blockers 5 on the liquid feeding route 4 are preferably located between the pressurizer for circulation 3 and the liquid supplier 6 in view of the liquid-pressure stability.
  • the piston rod 12 which stayed waiting in the bottom dead center begins to go up by the driving force of a stepping motor 13b through a ball screw 13a.
  • the liquid pressure having very little fluctuation is given to the dispersion liquid 2 filled and supplied in the cylinder when the liquid is circulated.
  • the small flow rate of the dispersion liquid 2 can be precisely transported to the spray coating device 7 by fixing the lifting speed of the piston rod 12.
  • the liquid pressure between the liquid-pressure blockers 5 located on the liquid feeding route 4 and the circulation route 8, i.e., the liquid pressure in and between the liquid supplier 6 and the spray coating device 7 equals the liquid pressure given by the liquid supplier.
  • the needle valve 26 which closed the atomized liquid discharger 23 opens, and a small quantity of the liquid having very little fluctuation can be discharged from the atomized liquid discharger 23 by the liquid pressure for spray coating given by the liquid supplier 6 to the dispersion liquid 2, regardless of the circulating liquid flow-rate.
  • the discharged dispersion liquid 2 is sprayed by the air for atomization supplied to an air cap 22 through another route (not shown).
  • a thin and uniform dispersed layer having a thickness of from about submicrons to a few microns can be formed by spray coating.
  • Fa has to be sufficiently large such that the sedimentation of the fine particles in the liquid supplier 6 and the spray coating device 7 may not be formed
  • Fb has to be sufficiently small such that a thin and uniform dispersed layer having a thickness of from about submicrons to a few microns can be formed.
  • functional separation to make Fa and Fb different from each other is important such that the following relationship can be satisfied: Fa > Fb .
  • Fa 10 ⁇ Fb .
  • Fig. 6 is a schematic view illustrating a cross section of a functionally separated electrophotographic photoreceptor, in which an undercoat layer 32, a charge generation layer (CGL) 33, a charge transport layer (CTL) 34 are layered in this order on an electroconductive substrate 31.
  • an undercoat layer 32 a charge generation layer (CGL) 33
  • CTL charge transport layer
  • Fig. 7 is a schematic view illustrating a cross section of a functionally separated electrophotographic photoreceptor, in which a charge generation layer (CGL) 33, a charge transport layer (CTL) 34 and a protective layer 35 are layered in this order on an electroconductive substrate 31.
  • CGL charge generation layer
  • CTL charge transport layer
  • Fig. 8 is a schematic view illustrating a cross section of a functionally separated electrophotographic photoreceptor, in which an undercoat layer 32, a charge generation layer (CGL) 33, a charge transport layer (CTL) 34 and a protective layer 35 are layered in this order on an electroconductive substrate 31.
  • CGL charge generation layer
  • CTL charge transport layer
  • the layered order of the charge generation layer (CGL) 33 and the charge transport layer (CTL) 34 may be reversible. Further, these layers may be a single layer including a charge generation material and a charge transport material.
  • the electroconductive substrate various known substrates can be used.
  • a metallic drum made of aluminium, copper, nickel, stainless, steel and the like, and substrates such as plastic films, plastic drums, glass drums and papers whose surfaces are applied with an electroconductive treatment can be used.
  • Specific examples of the substrates applied with an electroconductive treatment include such as substrates laminated with a metallic foil; substrates evaporated or sputtered with a metal, an electroconductive oxide and the like; and substrates coated with electroconductive materials such as metallic powders, carbon black, copper iodide and tin oxide, which are optionally coated together with a binder resin.
  • metallic drums, plastic films applied with an electroconductive treatment and plastic drums can be preferably used.
  • the undercoat layer 32 typically includes a resin as a main component. Considering that the photosensitive layer is coated on the undercoat layer using a solvent, the resin preferably has good solvent resistance against the organic solvent used for coating the photosensitive layer.
  • resins include watersoluble resins such as polyvinylalcohol, casein, polyacrylic natrium; alcohol-soluble resins such as nylon copolymer and nylon methoxymethylate; and cured resins forming three-dimensional network structures such as polyurethane, melamine resins, alkyd-melamine resins and epoxy resins.
  • fine particles of a metal oxide such as titanium oxide, silica, alumina, zirconium oxide, tin oxide and indium oxide or of a metal sulfide and metal nitride, or of these fine particles applied with electroconductive treatments may be optionally included in the undercoat layer.
  • organic fine particles such as fluorocarbon resins, silicone resins, acryl resins, melamine resins can be used.
  • the undercoat layer 32 can be formed by a dip coating method, a spray coating method, a bead coating method, etc.
  • the thus formed undercoat layer 32 preferably has a thickness of form about 0.1 to 15 ⁇ m, and more preferably from 0.3 to 5 ⁇ m.
  • the manufacturing method of the present invention can be used to form the undercoat layer 32.
  • the fine-particle dispersion liquid 2 including at least a solvent and fine particles for use in the present invention is formed by selecting from the above-mentioned fine particles for the undercoat layer 32 and the group of resin materials, and properly dispersing the materials with a ball mill, an attritor and a sand mill, etc.
  • the charge generation layer 33 includes a charge generation material as a main component, and a binder resin can be optionally used in the charge generation layer.
  • a charge generation material inorganic materials or organic materials can be used.
  • the inorganic materials include crystallized selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compound, amorphous silicon, etc.
  • amorphous silicon amorphous silicon formed from a dangling bond terminated with a hydrogen atom or a halogen atom, and amorphous silicon formed from a doped boron atom, a phosphorous atom, etc. are preferably used.
  • phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine, azulenium salt pigments, squaric acid methine pigments, azo pigments having carbazole skeletons, azo pigments having triphenylamine skeletons, azo pigments having diphenylamine skeletons, azo pigments having dibenzothiophene skeletons, azo pigments having fluorenone skeletons, azo pigments having oxadiazole skeletons, azo pigments having bisstilbene skeletons, azo pigments having distyryloxadiazole skeletons, azo pigments having distyrylcarbazole skeletons, perylene pigments, anthraquinone or polycyclic quinone pigments, quinoneimine pigments, diphenylmethane and triphenylmethane pigments, benzo
  • charge generation materials may be used alone or in combination.
  • binder resins optionally used for the charge generation layer 33 include polyamide, polyurethane, epoxy resins, polyketone, polycarbonate, silicone resins, acryl resins, polyvinylbutyral, polyvinylformal, polyvinylketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide and the like resins. These binder resins can be used alone or in combination.
  • a charge transport material may be optionally included in the charge generation layer.
  • a high-molecular weight charge transport material may be used as the binder resin for the charge generation layer 33.
  • a vacuum thin-film manufacturing method As a method for forming the charge generation layer 33, a vacuum thin-film manufacturing method, a casting method from liquid-solution dispersion methods, etc. can be used.
  • the vacuum thin-film manufacturing method include a vacuum-deposition method, a glow-discharge polymerization method, an ion-plating method, a sputtering method, a reactive sputtering method, CVD method, etc.
  • the above-mentioned materials are optionally dispersed with a binder resin by a ball mill, an attritor, a sand mill, etc. using a solvent such as tetrahydrofuran, cyclohexane, dioxane and butanone; and the dispersion liquid properly diluted is coated to form the charge generation layer.
  • a dip coating method, a spray coating method, a bead coating method, etc. can be used for coating the charge generation layer.
  • the thus formed charge generation layer 33 preferably has a thickness of from about 0.01 to 5 ⁇ m, and more preferably from 0.05 to 2 ⁇ m.
  • the manufacturing method of the present invention can be used for forming the charge generation layer 33.
  • the fine-particle dispersion liquid 2 including at least a solvent and fine particles for use in the present invention is formed by selecting from the above-mentioned fine particles of the charge generation materials and the group of resin materials as the components, and properly dispersing the materials with a ball mill, an attritor and a sand mill, etc.
  • the charge transport layer 34 includes a charge transport material and a binder resin.
  • the charge transport material and the binder resin are properly dissolved or dispersed in a solvent, and this is coated and dried to form the charge transport layer.
  • a plasticizer, an antioxidant, a leveling agent, etc. may be included in the charge transport layer besides the charge transport material and the binder resin.
  • charge transport material positive-hole transport materials and electron transport materials are available.
  • the electron transport materials known materials can be used. Specific examples of the electron transport materials include electron acceptors such as chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenon,2,4,5,7-7-tetranitro-9-fluorenon, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophene-4-one and 1,3,7-trinitrodibenzothiophene-5,5-dioxides.
  • electron acceptors such as chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenon,2,4,5,7-7-tetranitro-9-fluorenon, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,
  • These electron transport materials can be used alone or in combination.
  • the positive-hole transport material the following known electron-releasing materials can be used.
  • These positive-hole transport materials can be used alone or in combination.
  • poly-N-vinylcarbazole and the compounds disclosed in Japanese Laid-Open Patent Publications Nos. 50-82056 , 54-9632 , 54-11737 , 4-175337 , 4-183719 and 6-234841 are available.
  • N,N-bis(4-methylphenyl)-4-aminopolystyrene and the compounds disclosed in Japanese Laid-Open Publications Nos. 1-134457 , 2-282264 , 2-304456 , 4-133065 , 4-133066 , 5-40350 and 5-202135 are available.
  • formaldehyde condensation polymer of nitropyrene and the compounds disclosed in Japanese Laid-Open Publications Nos. 51-73888 , 56-150749 , 6-234836 and 6-234837 are available.
  • binder resins for use in the charge transport layer 34 include vinyl polymers such as polyvinylbutyral, polyvinylacetal, polyester, polycarbonate, polystyrene, polyestercarbonate, polysulfone, polyimide, polymethylmethacrylate and poly vinyl chloride, and their copolymers; and resins such as phenoxy resins, epoxy resins and silicone resins, or partially crosslinked resins thereof. These resins can be used alone or in combination.
  • the charge transport layer preferably has a thickness of from about 5 to 100 ⁇ m, and more preferably from 10 to 30 ⁇ m.
  • An antioxidant and a plasticizer used for a rubber, a plastic, a fat, etc. can be included in the charge transport layer 34.
  • a leveling agent can be included in the charge transport layer 34.
  • silicone oils such as a dimethyl silicone oil and a methyl phenyl silicone oil; and a polymer or an oligomer having a perfluoroalkyl group can be used.
  • the content of the leveling agent is preferably from 0 to 1 part by weight per 100 parts by weight of the binder resin.
  • Fine particles can be included in the charge transport layer 34.
  • the fine particles include inorganic fine particles such as titanium oxide, silica, tin oxide, aluminum oxide, zirconium oxide, indium oxide, silicon nitride, calcium oxide, zinc oxide and barium sulfate; or organic fine particles such as fluorocarbon resins, silicone resins, acryl resins and melamine resins.
  • a dip coating method, a spray coating method, a bead coating method, etc. can be used for coating the charge transport layer.
  • the manufacturing method of the present invention can be used for forming the charge transport layer 34.
  • the fine-particle dispersion liquid 2 including at least a solvent and fine particles for use in the present invention is formed by selecting from the above-mentioned fine particles of the charge transport materials and the group of resin materials as the components, and properly dispersing the materials with a ball mill, an attritor and a sand mill, etc.
  • the protective layer includes fine particles and a binder resin, and a charge transport material can be optionally included in the protective layer.
  • the fine particles include inorganic fine particles such as titanium oxide, silica, tin oxide, aluminum oxide, zirconium oxide, indium oxide, silicon nitride, calcium oxide, zinc oxide and barium sulfate; or organic fine particles such as fluorocarbon resins, silicone resins, acryl resins and melamine resins.
  • inorganic fine particles such as titanium oxide, silica, tin oxide, aluminum oxide, zirconium oxide, indium oxide, silicon nitride, calcium oxide, zinc oxide and barium sulfate
  • organic fine particles such as fluorocarbon resins, silicone resins, acryl resins and melamine resins.
  • the surface of these fine particles may be treated with an inorganic or an organic substance for the purpose of increasing the dispersibility.
  • Specific examples of the surface treatment include a water-repellent treatment such as a silane-coupling agent treatment, a fluorochemical silane-coupling agent treatment and a higher fatty-acid treatment.
  • a filler whose surface is treated with alumina, zirconia, tin oxide and silica can be used.
  • binder resins include vinyl polymers such as polyvinylbutyral, polyvinylacetal, polyester, polycarbonate, polystyrene, polyestercarbonate, polysulfone, polyimide, polymethylmethacrylate and poly vinyl chloride, and their copolymers; and resins such as phenoxy resins, epoxy resins and silicone resins, or partially crosslinked resins thereof. These resins can be used alone or in combination.
  • the same charge transport material which can be included in the charge transport layer 34 can be optionally included in the protective layer.
  • the protective layer 35 can be formed by a dip coating method, a spray coating method, a bead coating method, etc.
  • the thus formed protective layer 35 preferably has a thickness of from about 0.1 to 20 ⁇ m, and more preferably from 0.5 to 10 ⁇ m.
  • the manufacturing method of the present invention can be used for forming the protective layer 35.
  • the fine-particle dispersion liquid 2 including at least a solvent and fine particles for use in the present invention is formed by selecting from the above-mentioned fine particles for the protective layer 35 and the group of resin materials as the components, and properly dispersing the materials with a ball mill, an attritor and a sand mill, etc.
  • solvents may be used for the coating liquids forming the above-mentioned each layer 32 to 35 of an electrophotographic photoreceptor.
  • the solvent include ethers such as diethylether, dimethoxymethane, tetrahydrofuran and 1,2-dimethoxyethane; carbon hydrides such as toluene and xylene; ketones such as acetone, methyl ethyl ketone and cyclohexanone; esters such as methyl acetate and ethyl acetate; and alcohols such as methanol, ethanol and propanol. These solvents can be used alone or in combination.
  • the following dispersion liquids having the respective components were prepared to form an electrophotographic photoreceptor.
  • a dispersion liquid A Alkyd resin (tradename Bekkosol 1307-60-EL from Dainippon Ink & Chemicals, Inc.) 5 Melamine resin (tradename Super Bekkamin G-821-60 from Dainippon Ink & Chemicals, Inc.) 5 Titanium oxide (tradename CREL from Ishihara Sangyo Kaisha Ltd.) 10 Methyl ethyl ketone 50 Cyclohexanone 30
  • a dispersion liquid C1 Polycarbonate resin (tradename Z polyca from Teijin Chemicals Ltd. having a viscosity-average molecular weight of 50,000) 10 Spherical melamine (tradename Epostar S from Nippon Shokubai Co., Ltd.) 1.6 Tetrahydrofuran 200 Cyclohexanone 135 Tetrahydrofuran liquid solution including 1 % of silicone oil (tradenameKF50 from Shin-Etsu Silicone Co., Ltd.) 1 Charge transport material having the following formula (I) (triphenylamine derivative) 6
  • Tetrahydrofuran liquid solution including 200 parts of tetrahydrofuran, 135 parts of cyclohexanone and 1 % of silicone oil (tradename KF50 from Shin-Etsu Silicone Co., Ltd.) 1 Charge transport material having the 6 Formula (I) Polycarbonate resin (tradename Z polyca from Teijin Chemicals Ltd. having a viscosity-average molecular weight of 50,000) 10
  • Titanium oxide (tradename CREL from Ishihara Sangyo Kaisha Ltd.) 2 Polycarbonate resin (tradename Z polyca from Teijin Chemicals Ltd. having a viscosity-average molecular weight of 50,000) 6 Tetrahydrofuran 190 Cyclohexanone 70
  • the dispersion liquid A was coated by spraying on a rotating aluminium cylinder having a diameter of 30 mm to form an undercoat layer 32.
  • the spray coating device 7 was located 100 mm apart from the rotating aluminium cylinder and sprayed the cylinder reciprocating in the axial direction of the cylinder at a predetermined speed.
  • the flow rate of the liquid from the dispersion liquid supplier 6 to the spray coating device 7 was 10 cc/min. when the spraying was performed.
  • the cylinder was dried to the touch while rotating for about 20 min. Then, the rotation was stopped, and the cylinder was taken out to be dried in a drier.
  • the thickness of the undercoat layer 32 was 5 ⁇ m after dried.
  • the dispersion liquid was circulated by the method of the present invention.
  • the flow rate of the liquid circulated by the pressurizer for liquid circulation 3 was 800 cc/min.
  • the tenth prepared photoreceptor was a photoreceptor sample of Example 1.
  • the flow rate of the liquid from the dispersion liquid supplier 6 to the spray coating device 7 was 4 cc/min. when forming the charge generation layer 33 with the dispersion liquid B, 42 cc/min. when forming the charge transport layer 34 with the liquid solution C2 and 15 cc/min. when forming the protective layer 35.
  • the thickness of the charge generation layer 33 was 0.1 ⁇ m, that of the charge transport layer was 20 ⁇ m and that of the protective layer was 3 ⁇ m after dried.
  • the cylinder 11 in the dispersion liquid supplier 6 and the coating nozzle 21 in the spray coating device 7 were disassembled to find no deposition formed by sedimentation of the dispersed fine particles. In addition, no clogging was found at the tip of the coating nozzle 21.
  • each liquid discharged from the spray coating device 7 was collected in a bottle when starting to spray the tenth photoreceptor.
  • Each collected liquid was a liquid sample of Example 1.
  • the concentration of the fine particles in each liquid was determined as follows:
  • the concentration of the fine particles in each dispersion liquid after the liquid was prepared was measured by the same method mentioned above. The results are shown in Table 1.
  • the fine-particle concentrations of the liquid samples of Example 1 scarcely changes compared with those of the references. This is appraisable as an alternative property proving that the reproducibility of the content ratio of the fine particles in the formed layers is good, compared with that of the fine particles in the solid contents included in the dispersion liquids.
  • Example 1 The procedure for preparation of 10 photoreceptors in Example 1 was repeated except that the liquid circulation was stopped with the liquid-pressure blockers 5 to retain the dispersion liquid in the liquid supplier 6 and the spray coating device 7 when the spray was stopped.
  • the tenth prepared photoreceptor was a photoreceptor sample of Comparative Example 1.
  • each liquid discharged from the spray coating device 7 was collected in a bottle when starting to spray the tenth photoreceptor.
  • Each collected liquid was a liquid sample of Comparative Example 1.
  • the procedure for determination of the fine-particle concentration of the liquids in Example 1 was repeated to determine that of the liquids of Comparative Example 1.
  • the results are shown in Table 1. Compared with those of the liquid samples in Example 1, the fine-particle concentrations of the liquids decrease. This is appraisable as an alternative property proving that the reproducibility of the content ratio of the fine particles in the formed layers is poor, compared with that of the fine particles in the solid contents included in the dispersion liquids.
  • Example 2 The procedure for preparation of 10 photoreceptors in Example 1 was repeated except for using the dispersion liquid C1 instead of the dispersion liquid C2.
  • the tenth prepared photoreceptor was a photoreceptor sample of Example 2.
  • each liquid discharged from the spray coating device 7 was collected in a bottle when starting to spray the tenth photoreceptor.
  • Each collected liquid was a liquid sample of Example 2.
  • the procedure for determination of the fine-particle concentration of the liquids in Example 1 was repeated to determine that of the liquids of Example 2.
  • the results are shown in Table 2.
  • the fine-particle concentrations of the liquid samples of Example 2 scarcely changes compared with those of the references. This is appraisable as an alternative property proving that the reproducibility of the content ratio of the fine particles in the formed layers is good, compared with that of the fine particles in the solid contents included in the dispersion liquids.
  • Example 2 The procedure for preparation of 10 photoreceptors in Example 2 was repeated except that the liquid circulation was stopped with the liquid-pressure blockers 5 to retain the dispersion liquid in the liquid supplier 6 and the spray coating device 7 when the spray was stopped.
  • the tenth prepared photoreceptor was a photoreceptor sample of Comparative Example 2.
  • each liquid discharged from the spray coating device 7 was collected in a bottle when starting to spray the tenth photoreceptor.
  • Each collected liquid was a liquid sample of Comparative Example 2.
  • the procedure for determination of the fine-particle concentration of the liquids in Example 1 was repeated to determine that of the liquids of Comparative Example 2.
  • the results are shown in Table 2. Compared with those of the liquid samples in Example 2, the fine-particle concentrations of the liquids decrease. This is appraisable as an alternative property proving that the reproducibility of the content ratio of the fine particles in the formed layers is poor, compared with that of the fine particles in the solid contents included in the dispersion liquids Table 2 Fine-Particle Concentration (wt.
  • each photoreceptor sample prepared in Examples 1 and 2,and Comparative Examples 1 and 2 was equipped with a copier model No. MF200 from Ricoh Company, Ltd., and the initial copy image was evaluated using a test chart. Further, the copy image after a durability test in which 10,000 copies were produced was evaluated.

Landscapes

  • Photoreceptors In Electrophotography (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Nozzles (AREA)
  • Coating Apparatus (AREA)
EP20020000602 2001-01-11 2002-01-10 Liquid spray-coating method and electrophotographic photoreceptor formed by the method Expired - Lifetime EP1222964B1 (en)

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JP2001003860 2001-01-11
JP2001003860 2001-01-11
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JP2001131076 2001-04-27
JP2001368911A JP3748404B2 (ja) 2001-01-11 2001-12-03 電子写真感光体及びその製造方法
JP2001368911 2001-12-03

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JP4948757B2 (ja) * 2004-09-30 2012-06-06 旭化成建材株式会社 建築板の塗装方法
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JP4344381B2 (ja) * 2006-12-27 2009-10-14 中外炉工業株式会社 塗工液供給装置
JP5107651B2 (ja) * 2007-10-02 2012-12-26 タクボエンジニアリング株式会社 塗料供給用シリンジ
JP4833958B2 (ja) * 2007-12-26 2011-12-07 株式会社大気社 塗料供給設備
JP5338100B2 (ja) * 2008-03-25 2013-11-13 株式会社Ｉｈｉ 塗装装置の噴射量制御方法及び装置
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