JP2005352071A - Developing roller and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roller capable of preventing the occurrence of defective image such as spots, density unevenness, further, white image fogging as much as possible, satisfactorily corresponding to a color image and reliably obtaining a high quality image, and to provide an image forming apparatus equipped with the developing roller. <P>SOLUTION: The developing roller 1 comprises a shaft member 2 composed of a metallic pipe and one or more layers of resin layers 4 arranged on the outside in the radial direction. By applying the voltage of 8 kV to a corona discharge device disposed with an interval of 1 mm away from the outer circumferential surface, corona discharge is generated and the outer circumferential surface is electrified, wherein the maximum value of surface potential after 0.35 sec is 90 V or less. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing roller used in an image forming apparatus such as an electrophotographic apparatus such as a copying machine or a printer or an electrostatic recording apparatus, and an image forming apparatus using the developing roller.

  In an electrophotographic image forming apparatus such as a copying machine or a printer, a nonmagnetic developer (toner) is supplied to a latent image holding body such as a photosensitive drum holding a latent image, and toner is applied to the latent image on the latent image holding body. The latent image is visualized by adhering, and as one of the general development methods, on the outer periphery of the developing roller arranged with a small gap between the latent image holding member and the latent image holding member. There is a non-magnetic jumping development method in which charged toner is carried, and the developing roller is rotated in a state where a voltage is applied between the latent image holding member and the developing roller, thereby causing the toner to fly to the latent image holding member.

  The nonmagnetic jumping development method will be further described with reference to FIG. A small gap 92 is provided with respect to the photosensitive drum 95 between the toner supply roller 94 for supplying the toner and the photosensitive drum (latent image holding member) 95 holding the electrostatic latent image. The developing roller 91, the photosensitive drum 95, and the toner supply roller 94 rotate in the directions of the arrows in the drawing, and a predetermined voltage is applied between the photosensitive drum 95 and the developing roller 91. The toner 96 is supplied to the surface of the developing roller 91 by the toner supply roller 94, the toner 96 is adjusted to a uniform thin layer by the stratifying blade 97, and the toner 96 formed in the thin layer is exposed to the gap 92. It flies to the drum 95 and adheres to the latent image, and this latent image is visualized.

  In the figure, reference numeral 98 denotes a transfer unit, which transfers a toner image onto a recording medium such as paper. A cleaning unit 99 is configured to remove the toner 6 remaining on the surface of the photosensitive drum 95 after the transfer by the cleaning blade 99a.

  FIG. 2 is a cross-sectional view showing a conventional developing roller 91 used in the non-magnetic jumping developing method. The developing roller 91 is generally a solid columnar or hollow cylinder made of a highly conductive material such as metal. A resin layer 84 for optimizing the chargeability and adhesion to the toner or the frictional force between the developing roller and the stratified blade is provided on the outer periphery of the shaft member 82 (for example, Patent Documents). 1).

The shaft member 82 is preferably light in weight as long as it is permitted in terms of strength. Therefore, it is preferable that the shaft member 82 has a hollow cylindrical shape. In this case, the metal pipe 85 and the metal pipe 85 are attached to both ends of the metal pipe 85, respectively. These shaft caps 86 are provided with shaft portions 86a that constitute both ends of the shaft member 82 in the longitudinal direction, and are supported by roller support portions of the image forming apparatus.
JP 2002-14534 A

  In order to obtain a high-quality image by forming an image using a developing roller, the developer held on the developing roller always maintains a constant charge when it reaches the latent image holding member, and becomes a uniform charged state. It is required to be.

  In other words, when high image quality is required for an image forming apparatus such as a printer, or when trying to cope with color images, if the electrical characteristics of the developing roller vary across the entire surface of the roller, image defects such as spots and uneven density will occur. In addition, the problem of fogging of the white image occurs. Also, during continuous printing, the charge amount of the developer held on the developing roller may gradually change, and when a partially black image is printed, it is newly held at that part. In some cases, the charge amount of the developer is different from the surroundings, and non-uniform image defects may occur due to the non-uniformity of the developer charge distribution caused by this. These phenomena are likely to occur when the charge applied to the surface of the developing roller is difficult to escape.

  In this case, it is considered that the charge applied to the surface of the developing roller is attenuated mainly by being grounded from the surface through a conductive shaft member. For example, in a developing metal single sleeve used for magnetic toner development, Since the substrate is made of metal, it is very conductive, surface charge can easily flow into the grounding portion, and residual surface charge hardly poses a problem. However, the development roller used for non-magnetic one-component toner development using a semiconductive material as a base material or a roller provided with a coating layer on a metal surface is difficult to escape the residual charge on the surface and tends to remain for a long time. Inconvenience based on it will occur.

  The present invention has been made in view of such problems, and prevents image defects such as spots and density unevenness as well as generation of white image fog as much as possible, and copes well with color images. An object of the present invention is to provide a developing roller that can reliably obtain a high-quality image and an image forming apparatus including the developing roller.

<1> In the present invention, one or more resin layers are provided on the outer side in the radial direction of a shaft member that is attached by being axially supported at both ends in the length direction, and the nonmagnetic developer carried on the outer peripheral surface is held as a latent image. In the developing roller supplied to the body,
When the shaft member is made of a metal pipe, and a corona discharge is generated by applying a voltage of 8 kV to a corona discharger arranged with a distance of 1 mm from the outer peripheral surface to charge the outer peripheral surface. In this developing roller, the maximum value of the surface potential after 0.35 seconds is 90 V or less.
Hereinafter, the maximum value of the surface potential measured under the above conditions (interval, voltage, time) is simply referred to as “maximum surface potential”.

<2> The present invention is the developing roller according to <1>, wherein at least one resin layer is made of an ultraviolet curable resin or an electron beam curable resin containing a conductive agent.
In this specification, the electron beam curable resin does not contain a crosslinking agent, a polymerization initiator, or a cleavage aid, and has the property of allowing self-crosslinking to proceed with energy by electron beam irradiation without using these aids. It shall mean the resin it has. However, in actual production, these may be blended with a crosslinking agent or the like to form a layer, and the electron beam curable resin does not refuse to blend them with the crosslinking agent or the like.

  <3> In the present invention, in <1> or <2>, the resin layer made of an ultraviolet curable resin or an electron beam curable resin containing a conductive agent is coated with a solventless coating solution, and ultraviolet or electronic It is a developing roller formed by irradiating a line.

  <4> The present invention is the developing roller according to any one of <1> to <3>, wherein an elastic layer is disposed between the shaft member and the innermost resin layer.

  <5> The present invention is an image forming apparatus provided with the developing roller of any one of <1> to <4>.

  According to the invention of <1>, 0.35 when the outer peripheral surface is charged by applying a voltage of 8 kV to the corona discharger disposed at a distance of 1 mm from the outer peripheral surface to generate a corona discharge. Since the maximum value (maximum surface potential) of the surface potential after 2 seconds is set to 90 V or less, it is possible to prevent as much as possible the occurrence of image defects such as spots due to residual charges, uneven density, and even white image fogging. In addition, it is possible to reliably and stably obtain a high-quality image that can reliably maintain good image quality even during continuous printing or partial image printing, and can also cope with color images. Can do.

  According to the invention <2>, since at least one resin layer is made of an ultraviolet curable resin or an electron beam curable resin containing a conductive agent, heat or hot air is used instead of ultraviolet irradiation or electron beam irradiation. Compared to forming by drying and curing, it can save a lot of equipment and space for drying, and also suppress variation in film formation due to difficult control of drying process In addition, the resin layer can be formed with high accuracy.

  According to the invention <3>, since at least one resin layer is formed by applying a solvent-free coating solution and irradiating with ultraviolet rays or electron beams, the same effects as described above can be brought about.

  According to the invention <4>, since the elastic layer is disposed between the shaft member and the radially innermost resin layer, the resin layer is pressed against the latent image holding member or the stratified blade. The stress applied to the resin layer can be relieved, the durability of the resin layer can be improved, and the stress on the toner can also be relieved, thereby contributing to the formation of a stable image over a long period of time.

  According to the invention <5>, since the developing roller according to any one of <1> to <4> is provided, it is possible to prevent density unevenness and white image fog as much as possible. In addition, it is possible to reliably maintain a good image quality even during continuous printing or partial image printing, and to reliably and stably obtain a high-quality image that can also cope with a color image. .

  The embodiment of the present invention will be described in more detail. FIG. 3A is a cross-sectional view showing the developing roller of the present embodiment, and FIG. 3B is a side view corresponding to the view taken along the line bb in FIG. The developing roller 1 is formed by forming a semiconductive elastic layer 3 on the outer periphery of the shaft member 2 and further forming a semiconductive resin layer 4 on the elastic layer 3. The elastic layer 3 is essential. Not a configuration. The shaft member 2 includes a hollow cylindrical metal pipe 5 and caps 6 having shafts attached to both ends of the metal pipe 5, and the shaft caps serving as both longitudinal ends of the shaft member 2. 6 is provided with shaft portions 6a constituting both ends in the length direction of the shaft member 2, and is supported by a roller support portion of an image forming apparatus (not shown).

  The shaft member 2 is made of metal and has good conductivity. Although it does not specifically limit as a metal material used for the shaft member 2, For example, iron, stainless steel, aluminum, an alloy containing these, etc. can be used.

  As long as the thickness of the pipe is sufficient in strength, it is preferably thinner in terms of weight reduction, and can be set to, for example, 0.3 to 2 mm. In order to assemble the metal pipe 5 and the shaft cap 6, for example, as shown in FIG. 3B, a convex portion 5a provided on the metal pipe 5 and a concave portion 6b provided on the shaft cap 6 are provided. And the metal pipe 5 and the shaft cap 6 may be fixed by an adhesive, pinning or the like.

  Here, the resin layer 4 is composed of one layer or a plurality of layers, and at least one of them is preferably composed of an ultraviolet curable resin or an electron beam curable resin containing a conductive agent.

  The resin layer 4 can give a required charge amount to the toner and obtain a required toner conveyance amount according to the specifications of the toner and the image forming apparatus, and also requires a toner supply amount to the latent image holding member. Characteristics such as electric resistance and surface properties are set so as to be the same.

  Examples of the ultraviolet curable resin or electron beam curable resin forming the resin layer 4 include polyester resin, polyether resin, fluorine resin, epoxy resin, amino resin, polyamide resin, acrylic resin, acrylic urethane resin, urethane resin, and alkyd resin. , Phenol resin, melamine resin, urea resin, silicone resin, polyvinyl butyral resin, and the like. These can be used alone or in combination. Furthermore, modified resins in which specific functional groups are introduced into these resins can also be used.

  Although it does not specifically limit as an ultraviolet curable resin or an electron beam curable resin, The (meth) acrylate type resin composition containing a (meth) acrylate oligomer is suitable.

  Examples of such (meth) acrylate oligomers include urethane (meth) acrylate oligomers, epoxy (meth) acrylate oligomers, ether (meth) acrylate oligomers, ester (meth) acrylate oligomers, and polycarbonate (meth) acrylate oligomers. And fluorine-based and silicone-based acrylic oligomers.

  The (meth) acrylate oligomer includes polyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, bisphenol A type epoxy resin, phenol novolac type epoxy resin, polyhydric alcohol and ε-caprolactone adduct, and the like ( It can be synthesized by reaction with (meth) acrylic acid or by urethanizing a polyisocyanate compound and a (meth) acrylate compound having a hydroxyl group.

  A urethane type (meth) acrylate oligomer is obtained by urethanizing a polyol, an isocyanate compound, and a (meth) acrylate compound having a hydroxyl group.

  Examples of the epoxy-based (meth) acrylate oligomer may be any reaction product of a compound having a glycidyl group and (meth) acrylic acid. Among them, a benzene ring, a naphthalene ring, a spiro ring, a dicyclopentadiene, A reaction product of a compound having a cyclic structure such as tricyclodecane and having a glycidyl group and (meth) acrylic acid is preferred.

  Further, ether (meth) acrylate oligomers, ester (meth) acrylate oligomers and polycarbonate (meth) acrylate oligomers react with polyols (polyether polyols, polyester polyols and polycarbonate polyols) and (meth) acrylic acid for each. Can be obtained by:

  The resin composition for forming the resin layer 4 is blended with a reactive diluent having a polymerizable double bond for viscosity adjustment as necessary. As such a reactive diluent, for example, a monofunctional, difunctional or polyfunctional polymerizable compound having a structure in which (meth) acrylic acid is bonded to a compound containing an amino acid or a hydroxyl group by an esterification reaction or an amidation reaction Etc. can be used. These diluents are usually preferably used in an amount of 10 to 200 parts by weight per 100 parts by weight of the (meth) acrylate oligomer.

  As the conductive agent blended in the resin of the resin layer 4, an electronic conductive agent, an ionic conductive agent, or the like is used.

  Examples of the electronic conductive agent include conductive carbon such as ketjen black and acetylene black, rubber carbon such as SAF, ISAF, HAF, FEF, GPF, SRF, FT, and MT, and a color treated with oxidation ( Ink) carbon, pyrolytic carbon, natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium and other metals and metal oxides, polyaniline, polypyrrole, polyacetylene, etc. Conductive whiskers such as conductive polymer, carbon whisker, graphite whisker, titanium carbide whisker, conductive potassium titanate whisker, conductive barium titanate whisker, conductive titanium oxide whisker, and conductive zinc oxide whisker.

  The blending amount of these electronic conductive agents is preferably 100 parts by weight or less, for example, 1 to 100 parts by weight, particularly 1 to 80 parts by weight, especially 10 to 50 parts by weight, based on 100 parts by weight of the resin.

  However, when the carbon-based conductive agent is contained in the ultraviolet curable resin, it is preferably 20 parts by weight or less, particularly 10 parts by weight or less, especially 5 parts by weight or less based on 100 parts by weight of the resin. Since the carbon-based conductive agent easily absorbs ultraviolet rays when the amount exceeds the upper limit, the larger the amount of the conductive agent, the more difficult it is for the ultraviolet rays to reach the depth of the layer. is there.

  Examples of ionic conductive agents include perchlorate, chlorate, hydrochloride, bromine such as tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, benzyltrimethylammonium, and modified fatty acid dimethylethylammonium. Ammonium salts such as acid salts, iodates, borofluoride salts, sulfates, ethyl sulfates, carboxylates, sulfonates; alkali metals such as lithium, sodium, potassium, calcium, magnesium, alkaline earths Examples include metal perchlorates, chlorates, hydrochlorides, bromates, iodates, borofluorides, sulfates, trifluoromethyl sulfates, sulfonates, and the like. These ionic conductive agents are preferably used in an amount of 0.01 to 10 parts by weight, particularly 0.05 to 5 parts by weight, based on 100 parts by weight of the resin.

  In addition, the said electrically conductive agent may be used individually by 1 type, or may be used in combination of 2 or more types, In this case, it is also possible to combine an electronic conductive agent and an ionic conductive agent.

  In addition, when the conductive agent is a transparent conductive agent such as tin oxide, titanium oxide, zinc oxide, potassium titanate, barium titanate, nickel, copper, and other metal and metal oxides, ultraviolet rays are easily transmitted and ultraviolet curing is achieved. The effect of not hindering the polymerization of the mold resin is obtained. The blending amount of the transparent conductive agent is preferably 100 parts by weight or less, particularly 1 to 80 parts by weight, particularly 10 to 50 parts by weight with respect to 100 parts by weight of the resin.

  When the resin constituting the resin layer 4 is an ultraviolet curable resin, it is preferable to contain a polymerization initiator. As the ultraviolet polymerization initiator, known ones can be used. For example, 4-dimethylaminobenzoic acid, 4-dimethylaminobenzoic acid ester, 2,2-dimethoxy-2-phenylacetophenone, acetophenone diethyl ketal, alkoxy Benzophenone derivatives such as acetophenone, benzyldimethyl ketal, benzophenone and 3,3-dimethyl-4-methoxybenzophenone, 4,4-dimethoxybenzophenone, 4,4-diaminobenzophenone, alkyl benzoylbenzoate, bis (4-dialkylaminophenyl) Benzene derivatives such as ketones, benzyl and benzylmethyl ketal, benzoin derivatives such as benzoin and benzoin isobutyl ether, benzoin isopropyl ether, 2-hydroxy-2-methyl Lupropiophenone, 1-hydroxycyclohexyl phenyl ketone, xanthone, thioxanthone and thioxanthone derivatives, fluorene, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethyl Pentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1,2-benzyl-2-dimethylamino Such as -1- (morpholinophenyl) -butanone-1 and the like may be used alone or in combination of two or more.

  The blending amount of the ultraviolet polymerization initiator is preferably 0.1 to 10 parts by weight per 100 parts by weight of the (meth) acrylate oligomer.

  In the present invention, in addition to the above essential components, a tertiary amine such as triethylamine and triethanolamine, and an alkyl phosphine such as triphenylphosphine, if necessary, in order to promote the photopolymerization reaction by the photopolymerization initiator. A photopolymerization accelerator, a thioether photopolymerization accelerator such as p-thiodiglycol, and the like may be added. The amount of these compounds added is usually preferably in the range of 0.01 to 10 parts by weight per 100 parts by weight of the (meth) acrylate oligomer.

  For at least the outermost resin layer, it is preferable that the resin constituting the layer contains one or both of fluorine and silicon, thereby reducing the surface energy of the outermost resin layer. As a result, the frictional resistance of the developing roller can be reduced, the toner releasability can be improved, wear during long-term use can be reduced, and durability can be improved.

  As a raw material for forming an ultraviolet curable resin containing fluorine, it is preferable to contain a fluorine-containing compound having a polymerizable carbon-carbon double bond, and the fluorine-containing compound having a polymerizable carbon-carbon double bond. Or a composition comprising a blend of a fluorine-containing compound having a polymerizable carbon-carbon double bond and another type of polymerizable compound having a carbon-carbon double bond. Good.

  As the fluorine-containing compound having a polymerizable double bond between carbon atoms, fluoroolefins and fluoro (meth) acrylates are suitable.

As fluoroolefins, those having 2 to 12 carbon atoms in which 1 to all hydrogen atoms are substituted with fluorine are preferable. Specifically, hexafluoropropene [CF ₃ CF═CF ₂ , fluorine content 76 % By weight], (perfluorobutyl) ethylene [F (CF ₂ ) ₄ CH═CH ₂ , fluorine content 69 wt%], (perfluorohexyl) ethylene [F (CF ₂ ) ₆ CH═CH ₂ , fluorine containing 71% by weight], (perfluorooctyl) ethylene [F (CF ₂ ) ₈ CH═CH ₂ , fluorine content 72% by weight], (perfluorodecyl) ethylene [F (CF ₂ ) ₁₀ CH═CH ₂ , fluorine content 73% by weight], chlorotrifluoroethylene _[CF 2 = CFCl, fluorine content 49 wt%, 1-methoxy - (perfluoro-2 Chill-1-propene _{[(CF 3) 2 C =} CFOCH 3, fluorine content 63 wt%, 1,4-vinyl octafluorobutane _{[(CF 2) 4 (CH} = CH 2) 2, fluorine content 60 % By weight], 1,6-divinyldodecafluorohexane [(CF ₂ ) ₆ (CH═CH ₂ ) ₂ , fluorine content 64% by weight], 1,8-divinylhexadecafluorooctane [(CF ₂ ) ₈ ( CH = CH ₂ ) ₂ , fluorine content 67 wt%].

As the fluoro (meth) acrylate, a fluoroalkyl (meth) acrylate having 5 to 16 carbon atoms in which 1 to all hydrogen atoms are substituted with fluorine is preferable. Fluoroethyl acrylate (CF ₃ CH ₂ OCOCH═CH ₂ , fluorine content 34 wt%), 2,2,3,3,3-pentafluoropropyl acrylate (CF ₃ CF ₂ CH ₂ OCOCH═CH ₂ , fluorine content 44 _{wt%), F (CF 2)} 4CH 2 CH 2 OCOCH = CH 2 ( fluorine content 51 wt%), 2,2,2-trifluoroethyl acrylate _{[CF 3 CH 2 OCOCH = CH} 2, the fluorine content 37 wt%], 2,2,3,3,3-pentafluoropropyl acrylate [CF ₃ CF ₂ CH ₂ OCOCH = CH ₂ , fluorine content 47 wt%], 2- (perfluorobutyl) ethyl acrylate [F (CF ₂ ) ₄ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 54 wt%], 3- (perfluorobutyl ) -2-hydroxypropyl acrylate [F (CF ₂ ) ₄ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂ , fluorine content 49 wt%], 2- (perfluorohexyl) ethyl acrylate [F (CF ₂ ) ₆ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 59 wt%], 3- (perfluorohexyl) -2-hydroxypropyl acrylate [F (CF ₂ ) ₆ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂ , Fluorine content 55 wt%], 2- (perfluorooctyl) ethyl acrylate [F (CF ₂ ) ₈ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 62 wt%], 3- (perfluorooctyl) -2-hydroxypropyl acrylate [F (CF ₂ ) ₈ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂ , fluorine Content 59 wt%], 2- (perfluorodecyl) ethyl acrylate [F (CF ₂ ) ₁₀ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 65 wt%], 2- (perfluoro-3-methylbutyl) Ethyl acrylate [(CF ₃ ) ₂ CF (CF ₂ ) ₂ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 57 wt%], 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl acrylate [(CF _{3) 2 CF (CF 2)} 2 CH 2 CH (OH) CH 2 OCOCH = CH 2, the fluorine content 5 Wt%], 2- (perfluoro-5-methylhexyl) ethyl acrylate _{[(CF 3) 2 CF (} CF 2) 4 CH 2 CH 2 OCOCH = CH 2, fluorine content 61 wt%], 3- (par Fluoro-5-methylhexyl) -2-hydroxypropyl acrylate [(CF ₃ ) ₂ CF (CF ₂ ) ₄ CH ₂ CH (OH) CH ₂ OCOCH═CH ₂ , fluorine content 57 wt%], 2- (par Fluoro-7-methyloctyl) ethyl acrylate [(CF ₃ ) ₂ CF (CF ₂ ) ₆ CH ₂ CH ₂ OCOCH═CH ₂ , fluorine content 64 wt], 3- (perfluoro-7-methyloctyl) -2 -Hydroxypropyl acrylate [(CF ₃ ) ₂ CF (CF ₂ ) ₆ CH ₂ CH (OH) CH ₂ OCOCH = CH ₂ , Nitrogen content 60 wt%], 1H, 1H, 3H-tetrafluoropropyl acrylate [H (CF ₂ ) ₂ CH ₂ OCOCH═CH ₂ , fluorine content 41 wt%], 1H, 1H, 5H-octafluoropentyl Acrylate [H (CF ₂ ) ₄ CH ₂ OCOCH═CH ₂ , fluorine content 53 wt%], 1H, 1H, 7H-dodecafluoroheptyl acrylate [H (CF ₂ ) ₆ CH ₂ OCOC (CH ₃ ) = CH ₂ , Fluorine content 59 wt%], 1H, 1H, 9H-hexadecafluorononyl acrylate [H (CF ₂ ) ₈ CH ₂ OCOCH═CH ₂ , fluorine content 63 wt%], 1H-1- (trifluoromethyl ) Trifluoroethyl acrylate [(CF ₃ ) ₂ CHOCOCH═CH ₂ , fluorine content 51 wt%], 1H, 1H, 3H-hexafluorobutyl acrylate [CF ₃ CHFCF ₂ CH ₂ OCOCH═CH ₂ , fluorine content 48 wt%], 2,2,2-trifluoroethyl methacrylate [CF ₃ CH ₂ OCOC (CH ₃ ) = CH _2, fluorine content 34 wt%], 2,2,3,3,3-pentafluoro-propyl methacrylate _{[CF 3 CF 2 CH 2 OCOC} (CH 3) = CH 2, fluorine content 44 wt%, 2- (perfluorobutyl) ethyl methacrylate [F (CF ₂ ) ₄ CH ₂ CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 51 wt%], 3- (perfluorobutyl) -2-hydroxypropyl methacrylate _{[F (CF 2) 4 CH} 2 CH (OH) CH 2 OCOC (CH 3) = CH 2, fluorine-containing Rate 47% by weight], 2- (perfluorohexyl) ethyl methacrylate _{[F (CF 2) 6 CH} 2 CH 2 OCOC (CH 3) = CH 2, fluorine content 57 wt%], 3- (perfluorohexyl) 2-hydroxypropyl methacrylate [F (CF ₂ ) ₆ CH ₂ CH (OH) CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 53 wt%], 2- (perfluorooctyl) ethyl methacrylate [F ( _{CF 2) 8 CH 2 CH 2} OCOC (CH 3) = CH 2, fluorine content 61 wt%, 3-perfluorooctyl-2-hydroxypropyl methacrylate _{[F (CF 2) 8 CH} 2 CH (OH) CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 57 wt%], 2- (perfluorodecyl) ethyl methacrylate [F (CF ₂ ) ₁₀ CH ₂ CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 63 wt%], 2- (perfluoro-3-methylbutyl) ethyl methacrylate [(CF ₃ ) ₂ CF ( _{CF 2) 2 CH 2 CH 2} OCOC (CH 3) = CH 2, fluorine content 55 wt%], 3- (perfluoro-3-methylbutyl) -2-hydroxypropyl methacrylate _{[(CF 3) 2 CF (} CF ₂ ) ₂ CH ₂ CH (OH) CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 51 wt%], 2- (perfluoro-5-methylhexyl) ethyl methacrylate [(CF ₃ ) ₂ CF (CF _{2) 4 CH 2 CH 2 OCOC} (CH 3) = CH 2, fluorine content 59 wt%], 3- (perfluoro-5-methylhexyl) -2 Hydroxypropyl methacrylate _{[(CF 3) 2 CF (} CF 2) 4 CH 2 CH (OH) CH 2 OCOC (CH 3) = CH 2, fluorine content 56 wt%], 2- (perfluoro-7-methyl-octyl ) Ethyl methacrylate [(CF ₃ ) ₂ CF (CF ₂ ) ₆ CH ₂ CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 62 wt%], 3- (perfluoro-7-methyloctyl) -2- hydroxypropyl methacrylate _{[(CF 3) 2 CF (} CF 2) 6 CH 2 CH (OH) CH 2 OCOC (CH 3) = CH 2, fluorine content 59 wt%], 1H, 1H, 3H- tetrafluoropropyl methacrylate _{[H (CF 2) 2 CH} 2 OCOC (CH 3) = CH 2, fluorine content 51 wt%], 1H, 1H, 5 - octafluoro pentyl methacrylate _{[H (CF 2) 4 CH} 2 OCOC (CH 3) = CH 2, fluorine content 51 wt%], 1H, 1H, 7H- dodecafluoroheptyl methacrylate _{[H (CF 2) 6 CH} 2 OCOC (CH ₃ ) = CH ₂ , fluorine content 57 wt%], 1H, 1H, 9H-hexadecafluorononyl methacrylate [H (CF ₂ ) ₈ CH ₂ OCOC (CH ₃ ) = CH ₂ , fluorine content 61 % By weight], 1H-1- (trifluoromethyl) trifluoroethyl methacrylate [(CF ₃ ) ₂ CHOCOC (CH ₃ ) = CH ₂ , fluorine content 48% by weight], 1H, 1H, 3H-hexafluorobutyl methacrylate _{[CF 3 CHFCF 2 CH 2 OCOC} (CH 3) = CH 2, the fluorine content 4 Wt%] and the like are exemplified.

  The fluorine-containing compound having a polymerizable double bond between carbon atoms is preferably a monomer, an oligomer, or a mixture of a monomer and an oligomer. As an oligomer, a 2-20 mer is preferable.

  The compound having another polymerizable double bond between carbon atoms that may be blended with the fluorine-containing compound having a double bond between carbon atoms is not particularly limited. ) Acrylate monomers or oligomers or mixtures of monomers and oligomers are preferred.

  Examples of the (meth) acrylate monomer or oligomer include, for example, urethane (meth) acrylate, epoxy (meth) acrylate, ether (meth) acrylate, ester (meth) acrylate, and polycarbonate (meth) acrylate. Or an oligomer, the monomer or oligomer of a silicone type (meth) acryl, etc. can be mentioned.

  The (meth) acrylate oligomer is composed of a compound such as polyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, bisphenol A type epoxy resin, phenol novolac type epoxy resin, adduct of polyhydric alcohol and ε-caprolactone, It can be synthesized by reaction with (meth) acrylic acid or by urethanizing a polyisocyanate compound and a (meth) acrylate compound having a hydroxyl group.

  A urethane type (meth) acrylate oligomer is obtained by urethanizing a polyol, an isocyanate compound, and a (meth) acrylate compound having a hydroxyl group.

  Examples of the epoxy-based (meth) acrylate oligomer may be any reaction product of a compound having a glycidyl group and (meth) acrylic acid. Among them, a benzene ring, a naphthalene ring, a spiro ring, a dicyclopentadiene, A reaction product of a compound having a cyclic structure such as tricyclodecane and having a glycidyl group and (meth) acrylic acid is preferred.

  Furthermore, ether-based (meth) acrylate oligomers, ester-based (meth) acrylate oligomers and polycarbonate-based (meth) acrylate oligomers react with polyols (polyether polyols, polyester polyols and polycarbonate polyols) and (meth) acrylic acid, respectively. Can be obtained by:

  The raw material for forming the ultraviolet curable resin containing silicon preferably contains a silicon-containing compound having a polymerizable carbon-carbon double bond, and silicon having a polymerizable carbon-carbon double bond. The composition may be composed of only a contained compound, and is composed of a composition obtained by blending a silicon-containing compound having a polymerizable carbon-carbon double bond and another kind of polymerizable compound having a carbon-carbon double bond. May be.

  As the silicon-containing compound having a polymerizable double bond between carbon atoms, both-end-reactive silicone oils, one-end-reactive silicone oils, and (meth) acryloxyalkylsilanes are suitable. As the reactive silicone oil, those having a (meth) acryl group introduced at the terminal are preferable.

  Specific examples of the silicon-containing compound suitable for the present invention are shown below.

  One of these silicon-containing compounds may be used alone, or two or more thereof may be mixed and used, or another compound having a carbon-carbon double bond that does not contain silicon may be used.

  These silicon-containing compounds having a polymerizable carbon-carbon double bond and other compounds having no carbon-containing carbon-carbon double bond are preferably used as a monomer, an oligomer, or a mixture of a monomer and an oligomer.

  The other compound having a polymerizable double bond between carbon atoms that may be blended with the silicon-containing compound having a polymerizable double bond between carbon atoms is not particularly limited. ) Acrylate monomers or oligomers or mixtures of monomers and oligomers are preferred. As an oligomer, a 2-20 mer is preferable.

  Examples of the (meth) acrylate monomer or oligomer include urethane (meth) acrylate, epoxy (meth) acrylate, ether (meth) acrylate, ester (meth) acrylate, polycarbonate (meth) acrylate, and the like. And fluorine-based (meth) acrylic monomers or oligomers.

  The (meth) acrylate oligomer is composed of a compound such as polyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, bisphenol A type epoxy resin, phenol novolac type epoxy resin, adduct of polyhydric alcohol and ε-caprolactone, It can be synthesized by reaction with (meth) acrylic acid or by urethanizing a polyisocyanate compound and a (meth) acrylate compound having a hydroxyl group.

  A urethane type (meth) acrylate oligomer is obtained by urethanizing a polyol, an isocyanate compound, and a (meth) acrylate compound having a hydroxyl group.

  Examples of the epoxy-based (meth) acrylate oligomer may be any reaction product of a compound having a glycidyl group and (meth) acrylic acid. Among them, a benzene ring, a naphthalene ring, a spiro ring, a dicyclopentadiene, A reaction product of a compound having a cyclic structure such as tricyclodecane and having a glycidyl group and (meth) acrylic acid is preferred.

  Further, ether (meth) acrylate oligomers, ester (meth) acrylate oligomers and polycarbonate (meth) acrylate oligomers react with polyols (polyether polyols, polyester polyols and polycarbonate polyols) and (meth) acrylic acid for each. Can be obtained by:

  In addition, an appropriate amount of various additives can be added to the ultraviolet curable resin constituting the resin layer 4 as necessary.

  Further, it is preferable to disperse fine particles in the resin layer 4, thereby forming minute irregularities on the surface of the resin layer 4 to ensure the conveying force of the toner carried on the outer peripheral surface to the latent image holding member. Can be a thing.

  The fine particles are preferably rubber or synthetic resin fine particles or carbon fine particles. Specifically, silicone rubber, acrylic resin, styrene resin, acrylic / styrene copolymer, fluorine resin, urethane elastomer, urethane acrylate, melamine resin. One type or two or more types of phenol resins are preferred.

  The addition amount of the fine particles is preferably 0.1 to 100 parts by weight, particularly 5 to 80 parts by weight with respect to 100 parts by weight of the resin.

  The average particle diameter a of the fine particles is preferably 1 to 50 μm, particularly 3 to 20 μm. The thickness b of the resin layer in which fine particles are dispersed is preferably 1 to 50 μm, and the ratio a / b between the average particle diameter a (μm) of the fine particles and the thickness b (μm) is It is preferable to set it as 1.0-5.0, and an appropriate micro unevenness | corrugation can be formed in the surface of the resin layer 4 by making a / b ratio into this range.

  As a method of forming the resin layer 4 made of an ultraviolet curable resin or an electron beam curable resin, a coating liquid made of a composition containing the resin component and the conductive agent and other additives is applied to the surface. A method of irradiating with ultraviolet rays or electron beams is preferably employed. The coating liquid preferably contains no solvent, or a solvent having high volatility even at room temperature may be used as the solvent.

  As a method for applying the coating liquid, a dipping method in which a developing roller having no resin layer in the resin liquid is dipped in a dipping solution, a spray coating method, a roll coating method, or the like is appropriately selected according to the situation. be able to.

  The thickness of the resin layer 4 is not particularly limited, but is usually 1 to 500 μm, particularly 3 to 200 μm, and particularly preferably about 5 to 100 μm. If the thickness is less than 1 μm, the charging performance of the surface layer may not be sufficiently secured due to friction during long-term use. On the other hand, if the thickness exceeds 500 μm, the developing roller surface becomes hard and damages the toner. In some cases, the toner adheres to a latent image holding member such as a photosensitive member or a stratified blade, resulting in an image defect.

  Next, the elastic layer 3 will be described. Although the elastic layer 3 is not an essential component, the stress applied to the resin layer 4 when the resin layer 4 is pressed against the latent image holding member or the layered blade can be relieved, and the durability of the resin layer is improved. It is preferable to provide a semiconductive elastic layer 3 for such purposes as the elastic layer 3. As the elastic layer 3, an elastic body obtained by adding a conductive agent to an elastomer alone or a foam body obtained by foaming the elastomer is used. It is done. The elastomer that can be used here is not particularly limited, and nitrile rubber, ethylene-propylene rubber, styrene-butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, silicone rubber, urethane rubber, acrylic rubber, chloroprene rubber, butyl rubber, An epichlorohydrin rubber etc. are illustrated and these can be used individually or in combination of 2 or more types. Of these, ethylene-propylene rubber, butadiene rubber, silicone rubber, and urethane rubber are preferably used in the present invention. A mixture of these and other rubber materials is also preferably used. In particular, in the present invention, a resin having a urethane bond is preferably used.

  Moreover, these elastomers can be used as foam bodies that are chemically foamed using a foaming agent, or foamed by mechanically entraining air like polyurethane foam. In the present invention, a so-called RIM molding method may be used in a molding process for integrating the shaft member 2 and the elastic layer 3. That is, two types of monomer components constituting the raw material component of the elastic layer 3 are mixed and injected into a cylindrical mold and polymerized to integrate the shaft member 2 and the elastic layer 3. As a result, the molding process can be performed in about 60 seconds from the injection of the raw material to the demolding, so that the production cost can be greatly reduced.

  As the conductive agent added to the elastic layer 3, the same conductive agent blended in the resin constituting the resin layer 4 can be used.

In the present invention, the volume resistivity of the semiconductive elastic layer is adjusted to 1 × 10 ³ to 1 × 10 ¹⁰ Ω · cm, preferably 1 × 10 ⁴ to 1 × 10 ⁸ Ω · cm. If the resistance value is less than 10 ³ Ωcm, the charge may leak to the latent image holding member or the developing roller may be destroyed by the voltage. On the other hand, if the resistance value exceeds 10 ¹⁰ Ωcm, ground fog is likely to occur. Become.

  Since the developing roller 1 is used in contact with a latent image holding member, a stratified blade, etc., the elastic layer 3 preferably has a small compression set, specifically, 20% or less, more specifically 10% or less. Preferably there is. Use of polyurethane rubber as the rubber material is preferable because the compression set can be designed to be small.

  A cross-linking agent and a vulcanizing agent can be added to the semiconductive elastic layer 3 as necessary to make the elastomer into a rubbery material. In this case, a vulcanization aid, a vulcanization accelerator, a vulcanization acceleration aid, a vulcanization retarder, etc. can be used in any case of organic peroxide crosslinking and sulfur crosslinking. In addition to the above, peptizers, foaming agents, plasticizers, softeners, tackifiers, tackifiers, separating agents, mold release agents, extenders, and coloring agents commonly used as rubber compounding agents. Etc. can be added.

  The hardness of the elastic layer 3 is not particularly limited, but it is preferably 80 degrees or less, particularly 30 to 70 degrees in terms of Asker C hardness. In this case, if the hardness exceeds 80 degrees, the original function of the elastic layer, which relieves stress applied to the developing roller and toner, cannot be expressed, and for example, the contact area between the developing roller and the latent image holder is small. Therefore, there is a possibility that good development cannot be performed. Further, the toner is damaged, and the toner adheres to the photosensitive member or the layered blade. On the other hand, if the hardness is too low, the frictional force with the photoconductor and the layered blade increases, which may cause image defects such as jitter.

  Since the elastic layer 3 is used in contact with a photoreceptor or a layered blade, even when the hardness is set to a low hardness, it is preferable to make the compression set as small as possible, specifically 20% or less. It is preferable.

  In the present invention, the surface roughness of the elastic layer 3 is preferably 1 to 20 [mu] mRz, more preferably 1.5 to 18 [mu] mRz in terms of JIS 10-point average roughness. When the average roughness exceeds 20 μm Rz, it is necessary to form a thick coating layer of the developing roller, so that the surface of the developing roller becomes hard. As a result, the toner is damaged and the toner adheres to the latent image holding member or the stratified blade. May occur and cause image defects.

  On the other hand, when the average roughness is less than 1 μm Rz, when the coating layer is formed, the average roughness of the surface of the developing roller becomes too small, and the toner carrying amount decreases, so that the image density may be lowered. In the present invention, the surface roughness is measured using a surface roughness meter “Surfcom 590A” (manufactured by Tokyo Seimitsu Co., Ltd.) in a measurement length of 2.4 mm in a direction orthogonal to the axial direction and a measurement speed of 0.8. This is a value obtained by measuring 300 or more locations at 3 mm / sec and a cutoff wavelength of 0.8 mm so that there is no deviation in the length direction and circumferential direction of the roller.

The developing roller 1 of the present invention is not particularly limited, but the electrical resistance value when 100 V is applied is preferably 10 ⁴ to 10 ¹⁰ Ω, particularly 10 ⁵ to 10 ⁹ Ω. If this resistance value is less than 10 ⁴ Ω, gradation control may be extremely difficult, and if a photosensitive drum such as a photoreceptor is defective, a bias leak may occur. On the other hand, if the resistance value exceeds 10 ¹⁰ Ω, for example, when developing toner on a latent image holding member such as a photoconductor, the developing bias causes a voltage drop due to the high resistance of the developing roller itself, which is sufficient for development. In some cases, the development bias cannot be secured, and a satisfactory image density cannot be obtained. The resistance value can be measured by, for example, pressing the developing roller against a flat plate or cylindrical counter electrode with a predetermined pressure, applying a voltage of 100 V between the shaft member and the counter electrode, and obtaining the current value at that time. it can.

  As described above, it is important to control the resistance value of the developing roller appropriately and uniformly from the viewpoint of maintaining the electric field strength for moving the toner appropriately and uniformly. It is important for the toner charge amount to be optimized and uniform that the charge retention ability of the toner is controlled and kept uniform, and further that the surface residual potential is attenuated at a constant rate. In this case, the surface charge retention capability is usually examined by measuring the surface resistance by placing a pair of electrodes on the surface of the developing roller and applying a constant voltage between the two electrodes, but in this case the current is only on the surface. Therefore, the surface of the developing roller does not flow, but the developing roller surface cannot be accurately evaluated.

  Therefore, in the present invention, in a measurement environment of 22 ° C. and 50% RH, a voltage of 8 kV is applied to a corona discharger disposed at a distance of 1 mm from the surface of the developing roller to generate a corona discharge to charge the surface. In this case, the surface charge retention ability is evaluated based on the maximum value of the surface potential after 0.35 seconds, and the maximum value is 90 V or less, preferably 50 V or less. In this case, if the maximum value exceeds 90 V, the toner is supplied to the image forming body, and when the toner is removed from the surface of the developing roller, the charge in that portion remains there without escaping. Next, the charge amount of the toner charged at the same portion is low. In addition, the effective development bias varies due to the potential generated by the residual charge, and the toner development amount becomes non-uniform, which increases the possibility of causing image unevenness. Further, when the developing roller continues to rotate without supplying toner to the latent image holding member, the toner charge gradually increases, and in some cases, the electric field generated by the toner charging exceeds the maximum value. In some cases, a discharge occurs between the latent image holding member and the like, and an image defect may occur.

  Here, the reason why the surface potential is measured 0.35 seconds after charging due to the generation of corona discharge is as follows. That is, it is difficult to measure the surface potential immediately after charging by corona discharge, and since the very early surface potential is unstable, it is not preferable to control the characteristic value in this portion. Considering an actual process in image formation such as development, for example, when the developing roller is in the shape of a roller, the rotation speed is usually 0.35 sec / 1 rotation, and the residual charge on the surface may be controlled during this time.

  The measurement of the maximum surface potential of the developing roller can be performed by the apparatus shown in FIG. That is, both ends of the shaft member 2 of the developing roller 1 are held by the chuck 11 to support the developing roller 1, and a small corotron discharger (corona discharger) 12 and a surface potential meter 13 are illustrated in FIG. Thus, the measuring unit 14 arranged in parallel with a predetermined interval is disposed opposite to the surface of the developing roller 1 with a gap of 1 mm, and the measuring unit 14 is moved to the developing roller while the developing roller 1 is stationary. A method of measuring the surface potential while applying a surface charge by moving at a constant speed from one end to the other end in the length direction of 1 is suitably employed.

  In the present invention, an ultraviolet curable resin composition or an electron beam curable resin composition for forming a resin layer is applied to one side of a metal plate such as a copper plate or SUS so that the thickness after curing is 30 μm. The maximum surface potential measured in the same manner as described above for the resin layer formed by being cured by irradiating with ultraviolet rays or electron beams is preferably 150 V or less, particularly 90 V or less. In order to set the maximum surface potential of the resin layer to 150 V or less in this way, for example, an appropriate amount of an appropriate conductive agent may be blended in an ultraviolet curable resin or an electron beam curable resin composition.

  In order to realize a developing roller having a maximum surface potential of 90 V or less, the maximum surface potential of the resin layer formed as described above is preferably 150 V or less. Even when the maximum surface potential exceeds 150 V, a developing roller having a maximum surface potential of 90 V or less can be realized by reducing the thickness of the resin layer to, for example, 3 to 10 μm.

  The developing roller 1 of the present invention can be incorporated in an image forming apparatus using toner. Specifically, as shown in FIG. 1, a toner supplying roller 94 for supplying toner and an electrostatic latent image are held. A developing roller 91 is disposed between the photosensitive drum 95 (latent image holding member) 95 with a small gap 92 with respect to the photosensitive drum 95, and the developing roller 91, the photosensitive drum 95, and the toner supply roller 94. The toner 96 is supplied to the surface of the developing roller 91 by the toner supply roller 94 by applying a predetermined voltage between the photosensitive drum 95 and the developing roller 91. A uniform thin layer can be prepared by the blade 97, and the toner 96 formed in the thin layer can fly over the gap 92 to the photosensitive drum 95 to visualize the latent image. Note that the details of FIG. 1 have been described in the background art, and will not be described.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited to these.

  When the developing roller does not have an elastic layer, a resin layer is formed directly on the shaft member made of an aluminum pipe, or when the developing roller has an elastic layer, an elastic layer is formed on the shaft member. A rear resin layer is formed, and a developing roller having the structure shown in FIG. 3 is produced. Examples 1 to 10 are used. For comparison with the developing roller of the example, only the shaft member having no resin layer is used. A developing roller having a part of the configuration different from that of the present invention including the developing roller was prepared as Comparative Examples 1 to 3. Then, for the developing rollers of these examples and comparative examples, measurement and evaluation of roller characteristics and image evaluation were performed. The specifications of each developing roller and the results of these evaluations are shown in Tables 6-8.

In forming each resin layer, the materials shown in Table 6 were blended in parts by weight shown in “Formulation (parts by weight)” in Tables 7 and 8, and the shaft member was placed in a solution in which the blended resin material was dissolved. Immersion coating (dip method) or a coating made of the compounded resin material was applied with a roll coater (coater method), and then this was heat-cured (heated or air-dried), UV-cured, or electron-beam cured. .
Regarding the preparation of each sample, whether the resin was applied by the dip method or the coater method, and whether the curing process was performed by heat curing (heating or air drying), ultraviolet curing, or electron beam curing Are listed in the corresponding columns of Tables 7 and 8.
In order to cure the resin layer with ultraviolet rays, the UV light is irradiated at an illuminance of 400 mW and an integrated light quantity of 1000 mJ / cm ² using a UNICURE UVH-0252C apparatus manufactured by USHIO ELECTRIC CO., LTD. While rotating the developing roller coated with the resin layer. Was irradiated. Further, when the resin is cured by an electron beam, a rotating voltage is rotated using a Min-EB apparatus manufactured by Ushio Electric Co., Ltd. Electron beam irradiation was performed under the condition of an irradiation time of 1 minute.

  The presence / absence of the elastic layer and the material of the elastic layer when the elastic layer is formed are described in the column “Presence / absence / type of elastic layer”.

  When the elastic layer is made of urethane, propylene oxide and ethylene oxide are added to glycerin to obtain a molecular weight of 5000, and 100 parts by weight of a polyether polyol (OH value 33). Add 0 parts by weight, 1.5 parts by weight of silicone surfactant, 0.5 parts by weight of nickel acetylacetonate, 0.01 parts by weight of dibutyltin dilaurate and 0.01 parts by weight of sodium perchlorate and mix with a mixer. Thus, a polyol composition was prepared. After the polyol composition was stirred and degassed under reduced pressure, 17.5 parts by weight of urethane-modified MDI was added and stirred for 2 minutes, and then the shaft member was placed in and heated to 110 ° C. It was cast into a mold or a container and cured for 2 hours, and the outer periphery was polished to form an elastic layer having an outer diameter of 12 mm, an elastic layer thickness of 500 μm, and a total length of 210 mm.

  When the elastic layer is made of silicone, liquid silicone rubber is injected into the cavity of the mold in which the shaft member is inserted, and is cooled and cured in the mold. An elastic layer having a layer portion thickness of 300 μm and a total length of 210 mm was formed.

  The toner charge amount and toner transport amount in Tables 7 and 8 were determined as follows. In other words, a cartridge equipped with a developing roller is incorporated in the image forming apparatus, the developing roller is idled without printing, the cartridge is taken out, and the toner charge amount is measured by taking the toner on the surface of the developing roller into the Faraday gauge. Further, when the toner charge amount is measured as described above, the weight of the removed toner is measured, and the area of the developing roller surface portion from which the toner has been removed is calculated, whereby the toner weight per unit area is calculated. The obtained toner transport amount was used.

  The image evaluation was performed as follows. That is, the development roller of each example and comparative example is mounted on a commercially available printer having a nonmagnetic jumping development unit portion shown in FIG. 1, and a development bias voltage in which alternating current is superimposed on direct current is applied, Reverse jumping development was performed using a negatively charged non-magnetic one-component toner having an average particle diameter of 7 μm. “Initial” image evaluation is performed by printing a black image, a full white image, a halftone image, and a pattern image immediately after mounting the developing roller, and visually determining the print image quality for each evaluation item in the table. Judgment results were expressed in a five-step evaluation.

  In the five-level evaluation, 5 is “particularly good”, 4 is “good”, 3 is “pass level”, 2 is “slightly bad”, 1 is “NG”, and 3 or more are passed as products. It is a possible level.

  In addition, the environment is changed from low temperature and low humidity (15 ° C x 10%) to high temperature and high humidity (32 ° C x 85%), and in the same way, the judgment is based on the five-level evaluation of printed images (the larger the number, the less the influence of the environment). The results are shown in the “Environmental impact” column.

  Further, the image evaluation of “after enduring 10,000 sheets” was evaluated in the same manner as “initial stage” after continuously printing 10,000 images of 5% printing density.

  About the obtained developing roller, the resistance value when a voltage of 100 V was applied between the counter electrode (metal drum) was measured using the rotational resistance measuring device shown in FIG.

  Further, by using the apparatus shown in FIG. 4, a voltage of 8 kV is applied to the roller, the roller surface is charged by corona discharge, the measuring unit 14 is moved at a speed of 200 mm / sec, and the corona is charged. The surface potential after 2 seconds was measured. The shape and dimensions of the measurement unit are as shown in FIG. By this method, the roller surface was measured all over, and the maximum value among them was taken as the value of the surface potential. The measurement environment was controlled at a temperature of 22 ° C. and a humidity of 50%.

  As can be seen from Tables 7 and 8, good image evaluation results could be obtained with any of the developing roller samples of Examples.

  The developing roller according to the present invention includes a charging roller, a developing roller, a transfer roller, a paper feeding roller, a toner in an image forming apparatus such as a plain paper copying machine, a plain paper facsimile machine, a laser beam printer, a color laser beam printer, and a toner jet printer. It is preferably used as a supply roller.

It is a conceptual diagram which shows the image forming apparatus used for a nonmagnetic jumping phenomenon. It is sectional drawing which shows the conventional developing roller. It is sectional drawing and the side view which show the developing roller of embodiment which concerns on this invention. FIG. 3 is a conceptual diagram of an apparatus that applies charge to a developing roller and measures a surface potential. It is a figure which shows arrangement | positioning of the surface potentiometer and a discharger on a measurement unit. It is a conceptual diagram which shows a rotational resistance measuring device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing roller 2 Shaft 3 Elastic layer 4 Resin layer 5 Metal pipe 5a Metal pipe convex part 6 Shaft cap 6a Shaft part 6b Shaft cap concave part 11 Chuck 12 Corona discharger 13 Surface potential meter 14 Measurement unit 20 Rotation Resistance measuring instrument 21 Metal drum 22 Ammeter

Claims (5)

In a developing roller that supplies one or more resin layers on the outer side in the radial direction of a shaft member that is pivotally supported at both ends in the length direction and supplies a non-magnetic developer carried on the outer peripheral surface to a latent image holder ,
When the shaft member is made of a metal pipe, and a corona discharge is generated by applying a voltage of 8 kV to a corona discharger arranged with a distance of 1 mm from the outer peripheral surface to charge the outer peripheral surface. A developing roller in which the maximum value of the surface potential after 0.35 seconds is 90 V or less.   The developing roller according to claim 1, wherein at least one resin layer is made of an ultraviolet curable resin or an electron beam curable resin containing a conductive agent.   The resin layer comprising an ultraviolet curable resin or an electron beam curable resin containing a conductive agent is formed by applying a solventless coating liquid and irradiating with ultraviolet rays or an electron beam. The developing roller as described.   The developing roller according to claim 1, wherein an elastic layer is disposed between the shaft member and the innermost resin layer.   An image forming apparatus comprising the developing roller according to claim 1.

Images