JP2021060502A - Conductive roller - Google Patents

Abstract

To provide a conductive roller which minimizes the occurrence of fogging and appearance of stain on a tip of a printing paper sheet after printing, and enables high-quality printing.SOLUTION: A conductive roller 1 is provided, comprising a shaft 2, at least one elastic layer 3 formed on the outer periphery of the shaft 2, and a surface layer 4 provided on the outer periphery of the elastic layer. The roller has a surface resistance (logΩ) of 7.8 or greater and a surface roughness Rz in a range of 3.1-8.5 μm.SELECTED DRAWING: Figure 1

Description

The present invention relates to conductive rollers such as developing rollers and toner supply rollers used in image forming devices such as electrophotographic devices and electrostatic recording devices.

As an example of the electrophotographic printing process, there is a pressure developing method using a non-magnetic one-component toner. In this pressure developing method, the developing roller rotates while in contact with the photosensitive drum holding the electrostatic latent image, and develops by adhering the toner carried on the developing roller to the latent image on the photosensitive drum. Therefore, the developing roller needs to be an elastic body having conductivity.

In such a developing roller, an elastic layer made of rubber, a polymer elastomer, a polymer foam, or the like, which is imparted with conductivity by blending a conductive agent, is generally formed on the outer periphery of a shaft made of a good conductive material such as metal. A surface layer composed of one layer or a plurality of layers of a coating film is provided on the outer periphery of the elastic layer so as to obtain a desired surface texture.

In the developing roller, it is necessary not only to have a desired resistance value required for the developing roller, but also to set the surface resistance value of the developing roller to a desired value in order to suppress triboelectric charging. From this point of view, there is a conductive roller provided with a surface layer in which a conductive agent is added to a specific resin (Patent Document 1). According to the conductive roller of Patent Document 1, the resistance value on the surface of the developing roller can be set to a desired value, the triboelectric charge between the developing roller and the toner can be suppressed as much as possible, and a good image can be obtained. It is said that it can be surely obtained over a period of time.

Japanese Unexamined Patent Publication No. 2018-91883

The demand for improving the image quality in the image forming apparatus is incessant. For example, fog occurs when solid white printing is performed, or the tip of the printing paper becomes dirty due to toner spillage, which deteriorates the image quality of the printed image. It is necessary to suppress it as much as possible. In this respect, the conventional developing roller still has room for improvement.

Therefore, an object of the present invention is to provide a conductive roller that solves the above problems, suppresses fog and stains on the tip of printing paper after printing, and enables high-quality printing.

As a result of diligent research to solve the above problems, the present inventor has not enough to simply adjust the surface resistance value of the conductive roller, but has adjusted the surface resistance value of the conductive roller to a specific range. , Adjust the surface roughness to a specific range, and by combining this adjustment of the surface resistance value and the adjustment of the surface roughness, it is possible to suppress fog and stains on the tip of the printing paper after printing, and high-quality printing can be achieved. We found what we could do and came up with the present invention.

The conductive roller of the present invention is a conductive roller including a shaft, at least one elastic layer formed on the outer periphery of the shaft, and a surface layer arranged on the outer peripheral surface of the elastic layer.
The roller surface resistance value (logΩ) is 7.8 or more, and the surface roughness Rz is 3.1 to 8.5 μm.

According to the conductive roller of the present invention, the roller surface resistance value (logΩ) is 7.8 or more, and the surface roughness Rz of the roller is 3.1 to 8.5 μm, so that after printing. It suppresses fog and stains on the tip of printing paper, and can print with high image quality.

In the conductive roller of the present invention, the roller resistance value (logΩ) is preferably 6.0 or more, and the surface layer contains a resin, and the resin is made of an energy ray-curable polymer having a urethane skeleton. At least one selected from the group is preferable, and the elastic layer preferably contains a polymer having a urethane skeleton and a conductive agent. The conductive roller of the present invention is particularly suitable for use in a developing roller.

According to the present invention, it is possible to suppress fog and stains on the tip of the printing paper after printing, and to print with high image quality.

It is the schematic sectional drawing which shows an example of the conductive roller of this invention. It is the schematic sectional drawing which shows an example of the developing apparatus using the said developing roller.

Hereinafter, preferred embodiments of the conductive roller of the present invention will be described in more detail.
The conductive roller of the present invention includes a shaft (core metal) 2 as shown in FIG. 1 and an elastic layer 3 having at least one layer formed on the outer periphery of the shaft 2. A surface layer 4 arranged on the outer peripheral surface of the elastic layer 3 is provided. The conductive roller of the present invention is not limited to the laminated structure shown in FIG. 1, for example, between the elastic layer 3 and the surface layer 4, an intermediate layer composed of a single layer or a plurality of layers, for example, a resistance adjusting layer and various types. A resin coating layer can be provided. Further, the surface layer is not limited to one composed of one layer, and may be composed of two or more layers.

[shaft]
The shaft 2 is not particularly limited as long as it is a material having good conductivity, but usually a metal solid or hollow shaft such as steel, stainless steel, or aluminum is used.

[Elastic layer]
The elastic layer 3 is an elastic body obtained by blending an electronic conductive agent such as carbon black or an ionic conductive agent such as sodium perchlorate with an elastomer alone or a foam body obtained by foaming the elastomer to impart conductivity, or a UV curable type. An elastic body which is a resin material and contains an ionic conductive agent can be preferably used. In each case, an elastic body containing a polymer having a urethane skeleton and a conductive agent is preferable.

First, an elastic body to which conductivity is imparted by blending an electronic conductive agent such as carbon black or an ionic conductive agent such as sodium perchlorate with an elastomer alone or a foam body obtained by foaming the elastomer will be described.

Examples of the above-mentioned elastomer include silicone rubber, urethane rubber, polybutadiene rubber, polyisoprene rubber, natural rubber, styrene butadiene rubber, nitrile rubber, ethylene propylene rubber, acrylic rubber, epichlorohydrin rubber, chloroprene rubber, and mixtures thereof. Be done. Further, these elastomers can be chemically foamed by a foaming agent, or can be used as a foam body in which air is mechanically entrained and foamed like a polyurethane foam.

Among the elastomer alone or the foam formed by foaming the elastomer, it is preferable to use a polyurethane foam obtained from a polyurethane raw material containing a polyol component and an isocyanate component. This polyurethane foam will be described below.

In this case, the polyol component is not particularly limited, and a known material polyol for urethane foam production can be used, and a polyether-based polyol, a polyester-based polyol, a polyester polyether-based polyol, or the like can be used for rollers. It can be appropriately selected depending on the situation, but in particular, polyester polyol and polyether polyol are preferably used, and either one or both of them can be mixed and used.

More specifically, the polyether polyol is a polyether polyol obtained by addition polymerization of alkylene oxide such as polyethylene oxide or propylene oxide to glycerin or the like, a polyether polyol obtained by ring-opening polymerization of tetrahydrofuran or the like, or a poly. Examples thereof include polyether polyols such as tetramethylene glycol, ethylene glycol, propanediol, and butanediol.

The polyester polyol is based on a condensed polyester polyol obtained by condensing a dicarboxylic acid with a diol or triol, or a terminal of a lactone-based polyester polyol or a polyether polyol obtained by ring-opening polymerization of a lactone based on the diol or triol. Examples thereof include polyols such as ester-modified polyols in which the above is ester-modified with lactone.

These polyols are not particularly limited, but preferably have a number average molecular weight of 360 to 8,000, particularly 500 to 5,600. The number of functional groups is preferably 2.0 to 3.

The above-mentioned isocyanate is also not particularly limited, and can be appropriately selected and used from various conventionally known isocyanate compounds. Specific examples thereof include isophorone diisocyanate (IPDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), modified TDI, modified MDI, and modified HDI.

Usually, this polyurethane is blended with a conductive agent to impart or adjust the conductivity. As the conductive agent, a known ionic conductive agent or electronic conductive agent can be used, and further, the ionic conductive agent and the electronic conductive agent can be used in combination.

Examples of the ionic conductive agent include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (for example, lauryltrimethylammonium), hexadecyltrimethylammonium, octadecyltrimethylammonium (for example, stearyltrimethylammonium), benzyltrimethylammonium, and modified fatty acid dimethylethylammonium. Ammonium salts such as perchlorate, chlorate, hydrochloride, bromate, iodate, borohydrochloride, sulfate, ethyl sulfate, carboxylate, sulfonate, lithium, sodium , Ammonium metals such as potassium, calcium, magnesium and alkaline earth metals, chlorates, hydrochlorides, bromines, iodates, borohydrochlorides, trifluoromethylsulfates, sulfonic acids Examples include salt.

Examples of the electronic conductive agent include conductive carbons such as Ketjen Black and acetylene black; carbons for rubbers such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT; carbons for inks that have been oxidized. Examples thereof include pyrolysis carbon, natural graphite, artificial graphite; conductive metal oxides such as tin oxide, titanium oxide and zinc oxide; metals such as nickel, copper, silver and germanium.

Further, in addition to the polyol component, the isocyanate component and the conductive agent, an appropriate amount of known additives such as a defoaming agent, a cross-linking agent, a surfactant, a catalyst and a polymerization initiator are added to the polyurethane. can do.

When the polyurethane foam is used as an elastic layer, the isocyanate component, the polyol component, the conductive agent, and the additive added as needed are mixed and, for example, mechanically stirred and foamed to set a shaft (core metal). It can be obtained by casting into a mold and thermosetting to form an elastic layer made of polyurethane foam around the shaft.

Next, the elastic body 3 which is a UV curable resin material and contains an ionic conductive agent will be described.
As the UV curable resin material as the elastic layer 3, for example, the UV curable resin material described in JP2012-159736A can be used.

Examples of the UV curable resin material include (A) urethane (meth) acrylate oligomer, (B) (meth) acrylate monomer, (C) ionic conductive agent, and (D) photopolymerization initiator being irradiated with UV light. Can be obtained by doing. It can be obtained by wrapping a UV curable resin around the shaft by a die coating method, a curtain coating method, a comma coating method, a spray coating method, etc. while fixing and rotating the shaft (core metal) to form an elastic layer. it can.

The polyol used for the synthesis of the urethane (meth) acrylate oligomer (A) preferably has a molecular weight in the range of 500 to 5,600. If the molecular weight of the polyol used for synthesizing the urethane prepolymer is less than 500, the hardness becomes high, which makes it unsuitable for the layer of a developing roller. On the other hand, if it exceeds 5,600, the compression residual strain increases and image defects occur. In addition to being prone to occur, the viscosity becomes too high, making it difficult to coat uniformly.

The (D) photopolymerization initiator and the blending amount thereof can be appropriately selected within the same type and blending amount as those described in JP2012-159736A.

The ionic conductive agent (C) has an action of imparting conductivity to the elastic layer. Since the ionic conductive agent has transparency in addition to being dissolved in (A) urethane (meth) acrylate oligomer or (B) (meth) acrylate monomer, a thick elastic layer forming composition is applied on the shaft. However, the ultraviolet rays sufficiently reach the inside of the coating film, and the composition for forming an elastic layer can be sufficiently cured. Examples of such an ionic conductive agent include perchlorates such as tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, and modified fatty acid dimethylethylammonate, chlorates, and hydrochlorides. Ammonites such as bromine salts, iodates, borohydrochlorides, sulfates, ethyl sulfates, carboxylates, sulfonates; alkali metals such as lithium, sodium, potassium, calcium, magnesium, alkaline earth Examples thereof include metal perchlorates, chlorates, hydrochlorides, bromines, iodates, borohydrochlorides, sulfates, trifluoromethylsulfates, sulfonates and the like.

Among them, suitable ionic conductive agents in the present invention include, for example, sodium perchlorate (MP-100, manufactured by Showa Chemical Co., Ltd.) and an acrylic monomer solution of lithium imide (Sanconol MTGA-50R, Sanko Chemical Industry Co., Ltd.). (Manufactured by Co., Ltd.) and the like. These conductive agents may be used alone or in combination of two or more. The blending amount of the ionic conductive agent in the composition for forming an elastic layer depends on the type thereof, but is composed of (A) urethane (meth) acrylate oligomer and (B) (meth) acrylate monomer constituting the UV curable resin material. The range of 0.1 to 5.0 parts by mass, particularly 0.2 to 3.0 parts by mass is preferable with respect to 100 parts by mass in total.

In addition to the above, various known additives can be added to the resin material forming the elastic layer as long as the desired effect of the present invention is not impaired.

The thickness of the elastic layer made of the polyurethane foam or the UV curable resin material is appropriately set depending on the use of the conductive roller and the design of the electrophotographic equipment in which the roller is set, and is not particularly limited. , Usually 0.5 to 10 mm, particularly preferably 0.5 to 3 mm. This depends on the outer diameter of the roller, but if the diameter of the shaft is too small, image defects will occur due to insufficient rigidity.

[surface]
The surface layer formed directly on the elastic layer 3 or via various intermediate layers is preferably a resin coating layer, and the resin coating layer is selected according to the use of the roller and the like. It can be formed as a main material using known resins, and examples thereof include urethane resin, acrylic resin, acrylic urethane resin, fluororesin, and silicone resin.
A preferred embodiment is a urethane resin, an acrylic resin, and an acrylic urethane resin, and a particularly preferred embodiment is a resin which is at least one selected from the group consisting of an energy ray-curable polymer having a urethane skeleton.

Examples of the energy ray-curable resin include an ultraviolet curable resin, an electron beam curable resin, an infrared curable resin, and the like. Among them, the ultraviolet curable resin is preferable in terms of reaction rate and energy efficiency. Examples of the ultraviolet curable resin include a type using a radical-based photopolymerization initiator and a type using a cationic-based photopolymerization initiator. Among them, the radical-based photopolymerization initiator has a reaction rate. It is preferable in that it is fast and has few uncured impurities. These urethane resins may be used alone or in combination of two or more.

As the energy ray-curable urethane resin, for example, urethane (meth) acrylate can be preferably used. The urethane (meth) acrylate has one or more (meth) acryloyl groups (CH ₂ = CHCO− or CH ₂ = C (CH ₃ ) CO−) in one molecule and has a urethane bond (-NHCOO−). There is no particular limitation as long as it has one or more, and it may be either a monomer or an oligomer, and it can be appropriately selected depending on the intended purpose. Specific examples thereof include polybutadiene-based urethane (meth) acrylate, carbonate-based urethane (meth) acrylate, ester-based urethane (meth) acrylate, and ether-based urethane (meth) acrylate. These may be used alone or in combination of two or more.

Further, the surface layer resin composition may contain, if necessary, a photopolymerization initiator, a photopolymerization initiator, a catalyst, an antioxidant, an antioxidant, a conductive agent, a foam stabilizer, a filler, a vulcanizing agent, and foaming. Agents, plasticizers, softeners, tackifiers, anti-adhesives, separators, mold release agents, bulking agents, colorants, cross-linking agents, vulcanizing agents, polymerization inhibitors, roughness-imparting agents (particles), surface modification Conventionally known additives such as quality agents (for example, silicone, fluorine-based, etc.) can be appropriately blended. These may be used alone or in combination of two or more.

Examples of the photopolymerization initiator include 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid ester, 2,2-dimethoxy-2-phenylacetophenone, acetophenone diethyl ketal, alkoxyacetophenone, benzyl dimethyl ketal, benzophenone and 3, Benzophenone derivatives such as 3-dimethyl-4-methoxybenzophenone, 4,4-dimethoxybenzophenone, 4,4-diaminobenzophenone, alkyl benzoyl benzoate, bis (4-dialkylaminophenyl) ketone, benzyl and benzyl such as benzyl methyl ketal Derivatives, benzoin derivatives such as benzoin and benzoin isobutyl ether, benzoin isopropyl ether, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexylphenylketone, xanthone, thioxanthone and thioxanthone derivatives, fluorene, 2,4,6-trimethyl Benzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2-methyl-1- (4) -(Methylthio) phenyl) -2-morpholinopropane-1, 2-benzyl-2-dimethylamino-1- (morpholinophenyl) -butanone-1 and the like can be mentioned. Specifically, for example, IRGACURE907 (manufactured by BASF Japan Ltd.) and the like can be mentioned. These photopolymerization initiators may be used alone or in combination of two or more. The blending amount of the photopolymerization initiator can be 5 parts by mass or less, preferably 2 parts by mass or less, with respect to 100 parts by mass of the energy ray-curable urethane resin.

As the conductive agent, known ionic conductive agents and electronic conductive agents can be appropriately used. Among these, the ionic conductive agents include tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (for example, lauryltrimethylammonium), hexadecyltrimethylammonium, octadecyltrimethylammonium (for example, stearyltrimethylammonium), benzyltrimethylammonium, and modified fatty acid dimethylethyl. Ammonium salts such as perchlorate such as ammonium, chlorate, hydrochloride, bromine salt, iodate, borohydrochloride, sulfate, ethyl sulfate, carboxylate, ammonium salt such as sulfonate, lithium, Ammonium metals such as sodium, potassium, calcium and magnesium, perchlorates of alkaline earth metals, chlorates, hydrochlorides, bromine salts, iodates, borohydrochlorides, sulfates, trifluoromethylsulfates Examples include salts and sulfonates. The electronic conductive agent includes conductive carbon black such as Ketjen black and acetylene black, carbon black for rubber such as SAF, ISAF, HAF, FEF, GPF, SRF, FT and MT, and ink such as carbon oxide black. Various carbon blacks such as carbon black and heat-decomposed carbon black, natural graphite, artificial graphite, antimony-doped tin oxide (ATO), ITO, tin oxide, titanium oxide, metal oxides such as zinc oxide, nickel, copper, silver, germanium Metals such as polyaniline, polypyrrole, polyacetylene and other conductive polymers, carbon whiskers, graphite whiskers, titanium carbide whiskers, conductive potassium titanate whiskers, conductive barium titanate whiskers, conductive titanium oxide whiskers, conductive zinc oxide whiskers. Such as conductive whiskers and the like. The blending amount of the conductive agent can be 0.1 to 5 parts by mass, preferably 0.5 to 3 parts by mass with respect to 100 parts by mass of the energy ray-curable urethane resin.

(Surface particles)
The surface layer 4 preferably contains particles. By adjusting the surface roughness, the toner transportability and chargeability can be controlled, and in combination with the adjustment of the surface resistance of the roller, fog and stains on the tip of the printing paper can be suppressed. The material, particle size, blending ratio, etc. of the particles are appropriately selected so as to satisfy the surface roughness and surface resistance values expected in the present invention.
Specifically, as the surface layer particles, one or more of urethane resin particles, acrylic resin particles, melamine resin particles, silicone resin particles, fluorine resin particles, phenol resin particles, nylon resin particles, silica particles, etc. shall be used. Can be done.

Similar to the surface layer resin composition, the surface layer particle resin composition includes, if necessary, a photopolymerization initiator, a photopolymerization initiator, a catalyst, an antioxidant, an antioxidant, a conductive agent, and a foam stabilizer. Conventionally such as fillers, deliquescents, foaming agents, plasticizers, softeners, tackifiers, anti-adhesive agents, separators, mold release agents, bulking agents, colorants, cross-linking agents, vulcanizing agents, polymerization inhibitors, etc. Known additives can be appropriately blended. These may be used alone or in combination of two or more. Further, the suitable blending amounts of these are the same as those of the surface layer resin composition.

The average particle size of the surface layer particles can be about 0.1 to 15 μm. The desired surface roughness can be easily obtained in the range of 0.1 to 15 μm in average particle size. It is preferably 2 to 8 μm. The mixing ratio of the particles in the surface layer is preferably 5 to 100 parts by mass with respect to 100 parts by mass of the resin component in the surface layer.

The thickness of the surface layer 4 is appropriately set according to the type of resin constituting the resin layer, the use of the roller, the characteristics of the elastic layer, and the like, and is not particularly limited, but is usually 0.1 to 20 μm. In particular, it is preferably 0.5 to 10 μm. Here, the thickness of the surface layer 4 does not include the protruding portion of the particles.
Further, the surface layer 4 may be a single layer or a plurality of layers may be laminated, and may be usually 1 to 5 layers. Further, another resin layer may be provided between the elastic layer 3 and the surface layer 4 for the purpose of adjusting adhesiveness and electrical resistance.

The surface layer 4 is formed by dissolving and dispersing the above resin components, additives and preferably added particles in a solvent such as methyl ethyl ketone, methyl isobutyl ketone, toluene, ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate, and methylcyclohexane. The resin paint may be prepared, and the resin paint may be applied onto the elastic layer 3 by a known method such as dipping, spraying, or roll coater.

The surface layer 4 containing the above-mentioned resin and preferably further containing the above-mentioned particles has a roller surface resistance value (logΩ) of 7.8 or more and a roller surface roughness Rz of 3.1 to 8.5 μm. Is. When the roller surface resistance value and the surface roughness satisfy the above range, the chargeability of the toner carried on the developing roller is improved to cause fog when solid white printing is performed, and stains on the tip of the printing paper due to toner spillage. Can be suppressed. This mechanism is not always clear, but the inventor estimates as follows.
When the roller surface resistance is less than 7.8, the residual potential of the roller surface immediately after the application to the roller is completed becomes small, and the decay with time is fast. If the roller residual surface potential is not appropriate, the amount of toner charged is small or back-charged toner is likely to be generated, and such toner gets on the photoconductor, especially in solid white printing after being left in high temperature and high humidity. It is transferred to paper and fog occurs. If the degree is worse, the toner cannot be retained on the developing roller or the photoconductor, and toner spills occur.
When the surface roughness Rz of the roller is less than 3.1 μm, the unevenness of the developing roller is smaller than the toner particle size, and the toner deteriorates due to an excessive load on the layer regulation blade and the photoconductor when the toner is applied. However, the amount of toner charge that should originally appear becomes smaller. Due to the decrease in the amount of toner charged, fog and toner spillage occur during solid white printing as described above.
Further, when the surface roughness Rz of the roller is larger than 8.5 μm, the unevenness of the developing roller is larger than the toner particle size, so that the toner triboelectric charging becomes insufficient and the toner charging amount becomes small. Occasionally fog and toner spills occur.

Fog and toner spills cannot be sufficiently suppressed by simply adjusting either the roller surface resistance value or the surface roughness, and according to the present invention, both the roller surface resistance value and the surface roughness satisfy the above numerical range. This can prevent fog and toner spillage.

Both fog and toner spillage occur when the triboelectric charging of the toner and the movement of the electric potential are not normal. If toner spills can be suppressed, fog can also be suppressed. Therefore, in the examples described later, only the fog is evaluated, but in the examples in which the fog can be suppressed, the toner spill can also be suppressed.

The roller surface resistance value (logΩ) is a value when a voltage of 100 V is applied to both ends of the conductive roller with a load of 500 g applied. More specifically, seven copper plates with a width of 1 cm are lined up, a roller is installed on a jig with a width of 2.5 cm between the copper plates, the above load is applied to both ends, and the resistance value between the adjacent copper plates is measured on the roller surface. It was used as the resistance value.

The roller surface resistance value can be set to 7.8 or more by adjusting the types and blending ratios of the resin, the conductive agent, the particles, and other surface layer components contained in the surface layer. A preferable roller surface resistance value (logΩ) is 8.0 or more. The upper limit of the roller surface resistance value (logΩ) can be about 12.0.

The surface roughness can be set so that the ten-point average roughness Rz is in the range of 3.1 to 8.5 μm by adjusting the particle size, the particle size distribution, and the mixing ratio of the particles to be blended in the surface layer. The preferred surface roughness Rz is 4-8 μm. The measurement of the ten-point average roughness Rz is performed by a surface roughness measuring instrument for measuring the ten-point average roughness Rz of JIS B0601-1994. Measurements were carried out using a 5 μm terminal at a speed of 0.8 mm and a measurement width of 4.0 mm.

The conductive roller of the present invention preferably has a roller resistance value (logΩ) of 6.0 or more. When it is 6.0 or more, fog and toner spill can be further suppressed. The preferred roller resistance value (logΩ) is 6.5 or more. The upper limit of the roller resistance value (logΩ) is not particularly limited, but can be about 9.

The conductive roller of the present invention is not particularly limited, but is applied to a developing roller, a toner supply roller, and the like used in an electrophotographic apparatus, and is particularly preferably provided to a developing roller. The developing roller is usually arranged in contact with or close to the surface of a latent image holder such as a photosensitive drum holding an electrostatic latent image, and is rotated to apply a developer carried on the surface to the surface of the latent image holder. It is supplied to visualize the electrostatic latent image held on the surface of the latent image holder. Specifically, as shown in FIG. 2, the development roller 1 of the present invention is developed as the development roller 1 shown in FIG. 1 between the toner supply roller 5 for supplying toner and the photosensitive drum 6 holding an electrostatic latent image. The rollers are arranged in contact with or close to the photosensitive drum 6, the toner 7 is supplied to the developing roller 1 by the toner supply roller 5, and this is supported on the surface of the developing roller 1 and is made uniform by the stratified blade 8. After preparing a thin layer, toner is supplied to the photosensitive drum 6 from the thin layer, and the toner is adhered to the electrostatic latent image on the surface of the photosensitive drum to visualize the latent image. In the figure, reference numeral 9 is a transfer unit, reference numeral 10 is a cleaning unit, and reference numeral 11 is a cleaning blade.

The conductive roller of the present invention will be specifically described with reference to Examples and Comparative Examples, but the conductive roller of the present invention is not limited to these Examples.

[Creation of elastic layer]
80 parts by mass of urethane acrylate oligomer, 20 parts by mass of hydroxyl group-containing (meth) acrylate, 0.5 parts by mass of photopolymerization initiator ("IRGACURE907" manufactured by Ciba Speciality Chemicals), ionic conductive agent (lithium salt) ("EF" manufactured by Mitsubishi Materials Co., Ltd. -N115 ") 0.25 parts by mass were weighed and stirred. The substrate was coated with a die coat to a thickness of 1.0 mm. UV was irradiated with the H valve of a UV lamp manufactured by FusionUV (irradiation conditions: 1, The coating material was cured at 500 mJ / cm ² ) to obtain an elastic layer.

The surface resin, surface particles, and photopolymerization initiator shown in Table 1 (“IRGACURE 907” manufactured by Ciba Speciality Chemicals) are weighed, methoxypropyl acetate is added to adjust the paint viscosity to about 85 cp, and the surface layer is stirred. A paint was obtained. The surface paint was applied to the surface of the elastic layer by a roll coating method. After that, UV was irradiated with an H valve of a UV lamp manufactured by FusionUV (irradiation condition: irradiation condition: 1). , 500 mJ / cm ² ), and the coating film was cured to obtain a surface layer.

The surface resin and surface particles in Table 1 are as follows.
(Surface resin)
SN34: A resin synthesized from a polyester-based polyol (average molecular weight 1000), TDI, and 2-hydroxyethyl acrylate. Made by Asia Industry Co., Ltd.
PX31-264: A resin synthesized from a polyester-based polyol (average molecular weight 500), IPDI, and 2-hydroxyethyl acrylate. Made by Asia Industry Co., Ltd.
PX31-266: A resin synthesized from a polyester-based polyol (average molecular weight 500), TDI, and 2-hydroxyethyl acrylate. Made by Asia Industry Co., Ltd.
PX31-269: A resin synthesized from a polycarbonate-based polyol (average molecular weight 500), TDI, and 2-hydroxyethyl acrylate. Made by Asia Industry Co., Ltd.
Origo42: A resin synthesized with ammonium ion-based polyol, TDI-based prepolymer, and 2-hydroxyethyl acrylate. Made by Hiroyuki Hiraizumi
PX31-75: A resin synthesized with a polyether polyol (average molecular weight 2000), TDI, and 2-hydroxyethyl acrylate. Made by Asia Industry Co., Ltd.
PC006: A resin synthesized from a polycarbonate-based polyol (average molecular weight 2000), IPDI, and 2-hydroxyethyl acrylate. Made by Asia Industry Co., Ltd.

(Surface particles)
TF9207 …… Polytetrafluoroethylene particles. Average particle size 4 μm. Blending ratio to resin 35 parts. Made by 3M
TF9207 Classification 1 …… Particles obtained by cutting large particles of TF9207 by classification. Blending ratio to resin 35 parts.
TF9207 Classification 2 …… Particles obtained by cutting large particles of TF9207 by classification (cut rate lower than classification 2) 35 parts of compounding ratio to resin.
UCN5050 …… Urethane particles. Blending ratio to resin 15 parts. Average particle size 5 μm. Made by Dainichiseika Kogyo Co., Ltd.
MM120T …… Urethane particles. Blending ratio to resin 35 parts. Average particle size 2 μm. Made by Negami Kogyo Co., Ltd.
SE006T …… Acrylic particles. Blending ratio to resin 15 parts. Average particle size 6 μm. Made by Negami Kogyo Co., Ltd.
UCN5070 …… Urethane particles. Blending ratio to resin 15 parts. Average particle size 7 μm. Made by Dainichiseika Kogyo Co., Ltd.
C600 …… Urethane particles. Average particle size 10 μm. Blending ratio to resin 15 parts. Manufactured by Negami Kogyo Co., Ltd. The surface layer contains a photopolymerization initiator and a surface modifier in addition to the surface layer resin and the surface layer resin.

The test sample (laminated body) having the above elastic layer and surface layer was evaluated as follows.

[Resistance value of surface layer and roller]
The roller surface resistance value and the roller resistance value were calculated by applying a load of 500 g to both ends and applying a voltage of 100 V in a state of a total pressure of 1000 g.

[Judgment of image defects]
Using a commercially available monochrome laser printer, the occurrence of fog on solid white printed printing paper was measured by QEA's PIAS-II by the number of black spots per screen, and the average fog was obtained. The black spots on the printing paper are nothing but black toner that should not exist. The average fog value is preferably 80 or less.

Table 1 also shows the surface roughness Rz, the roller surface resistance value, the roller resistance value, and the fog average value. From Table 1, the fog average value was low in Examples 1 to 8. Further, in Comparative Examples 1, 2, 5 and 6, the roller surface roughness Rz was low and the fog average value was high. In Comparative Examples 3 and 4, the surface resistance value was low and the fog average value was high.

1 Conductive roller (development roller)
2 Shaft 3 Elastic layer 4 Surface layer

Claims (5)

In a conductive roller including a shaft, at least one elastic layer formed on the outer periphery of the shaft, and a surface layer arranged on the outer peripheral surface of the elastic layer.
A conductive roller having a roller surface resistance value (logΩ) of 7.8 or more and a surface roughness Rz of 3.1 to 8.5 μm. The conductive roller according to claim 1, wherein the roller resistance value (logΩ) is 6.0 or more. The conductive roller according to claim 1 or 2, wherein the surface layer contains a resin, and the resin is at least one selected from the group consisting of an energy ray-curable polymer having a urethane skeleton. The conductive roller according to any one of claims 1 to 3, wherein the elastic layer contains a polymer having a urethane skeleton and a conductive agent. The conductive roller according to any one of claims 1 to 4, wherein the conductive roller is a developing roller.

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