JP2006163112A - Conductive elastic member for image forming apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive elastic member for an image forming apparatus capable stably obtaining a uniform resistance that undergoes small environmental variation and small variation by current application, and to provide an image forming apparatus using the conductive elastic member. <P>SOLUTION: The conductive elastic member for an image forming apparatus is based on an elastic body obtained by blending an elastic resin material with an ionic conductive substance to adjust the resistance of the material to 7-9 [logΩ], wherein a resin having an electric resistance of 11-13 [logΩ] is used as the elastic resin material. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a conductive elastic member for performing charging, development, transfer, intermediate transfer, toner supply, cleaning, and the like in an image forming apparatus such as a copying machine or a printer, and more particularly from a photosensitive drum when forming a color image. The present invention relates to a conductive elastic member suitably used as an intermediate transfer member that once transfers and holds a toner image on its surface and transfers it to a recording medium.

  Conventionally, OA equipment such as copiers and printers include belts, rollers, drums for charging, developing, transferring, intermediate transfer, toner layer formation, toner transport, toner stirring, cleaning, fixing, paper transport, etc. A member such as a blade is used.

  In many cases, these members are required to be soft, and are formed mainly of a rubber-like elastic body or a foam body. Further, in these applications, usually a conductivity of about 4 to 10 [logΩ] is often required. In that case, the rubber-like elastic body or foam body is imparted with conductivity by adding a conductive agent. It is done.

  Here, as the material constituting the rubbery elastic body and foam body, solid rubber vulcanizates such as isoprene rubber, ethylene propylene rubber, silicone rubber, epichlorohydrin rubber, acrylonitrile butadiene rubber, and polyol are cured with isocyanate. Polyurethane etc. are used. Examples of the conductive agent include electronic conductive agents such as carbon black and metal oxides, alkali metals, alkaline earth metals, chlorides of quaternary ammonium salts, perchloric oxides, borofluorides, alkyl sulfates, and carboxyls. An ionic conductive agent such as an oxide is used (Patent Document 1: JP 2000-26719 A).

  In this case, the conductive elastic member for the image forming apparatus is required to have a resistance value that is stable without variation at the predetermined value. However, when an electronic conductive agent is used as the conductive agent, the resistance is reduced. Although it is relatively easy, there is a drawback that the resistance value is likely to vary, and the resistance value is likely to increase due to continuous energization. On the other hand, the ionic conductive agent can obtain an elastic body or foam body having a uniform resistance value without variation, and there is little increase in the resistance value due to continuous energization, but the fluctuation range of the resistance value due to changes in the temperature / humidity environment In this case, if an attempt is made to reduce the environmental fluctuation range, the increase in energization tends to deteriorate. In addition, it is difficult to reduce the resistance of ionic conductive agents, and the current situation is that the increase in energization becomes worse when trying to obtain a low resistance.

JP 2000-26719 A

  The present invention has been made in view of the above circumstances, and is a conductive elastic member for an image forming apparatus capable of stably obtaining a uniform resistance value with small resistance fluctuation and environmental fluctuation of the resistance value, and the conductivity. An object of the present invention is to provide an image forming apparatus using an elastic member.

  As a result of intensive studies to achieve the above object, the present inventor obtained an elastic body having a resistance value adjusted to 7 to 9 [log Ω] by adding an ionic conductive substance to the elastic resin material, and this elasticity is obtained. When manufacturing a conductive elastic member for an image forming apparatus with a body, by using a resin having an electric resistance of 11 to 13 [log Ω] as the elastic resin material, it is possible to obtain an environmental resistance characteristic and an electric current fluctuation characteristic of the electric resistance. An excellent conductive elastic member can be obtained. Especially when lithium imide is used as an ionic conductive substance, these fluctuation characteristics are excellent, the resistance value is uniform, and good performance is stably exhibited. The present inventors have found that a conductive elastic member can be obtained and can be suitably used as a high-performance transfer member or the like, and have completed the present invention.

  That is, when the resistance value of the elastic resin material is adjusted to 7 to 9 [log Ω] suitable for image formation by adding an ion conductive substance, the resistance value of the elastic resin material is compared with 11 to 13 [log Ω]. While having a relatively high resistance value, a relatively large amount of conductive agent is added so as to obtain a predetermined resistance value, thereby obtaining good environmental variation characteristics and energization variation characteristics. It has been found that by forming a conductive elastic member using a material, it is possible to obtain a conductive elastic member that is excellent in these fluctuation characteristics, has excellent resistance uniformity, and can stably exhibit good performance. Is. In addition, although lithium imide is an ionic conductive agent that has a relatively large resistance increase due to energization, although it is excellent in environmental stability of the resistance value, the resistance value can be increased by combining with an elastic resin material having the above specific resistance value. It has been found that a conductive elastic body having improved environmental fluctuation characteristics and current supply characteristics can be obtained.

Therefore, the present invention is a conductive elastic member for an image forming apparatus mainly composed of an elastic body in which an ion conductive substance is added to an elastic resin material and the resistance value is adjusted to 7 to 9 [log Ω].
Provided is a conductive elastic member for an image forming apparatus, wherein a resin having an electric resistance of 11 to 13 [log Ω] is used as the elastic resin material.
Moreover, this invention provides the said conductive elastic member for image forming apparatuses which contains lithium imide as said ion conductive substance as a suitable embodiment.

  According to the conductive elastic member of the present invention, resistance fluctuations in the environment and energization fluctuations are small, a uniform resistance value can be stably obtained, and good performance can be stably exhibited. Therefore, the image forming apparatus of the present invention using this conductive elastic member as an intermediate transfer member can stably obtain a good image.

Hereinafter, the present invention will be described in more detail.
As described above, the conductive elastic member for an image forming apparatus according to the present invention is mainly composed of an elastic body in which an ionic conductive substance is added to an elastic resin material and the resistance value is adjusted to 7 to 9 [log Ω]. It is.

  Here, the elastic resin material may have a resistance value of 11 to 13 [log Ω], preferably 11.5 to 12.5 [log Ω], and may be a known rubber, elastomer, foam body, or the like. However, in the present invention, polyurethane is particularly preferably used, and polyurethane obtained by reaction curing of an isocyanate component and a polymer polyol component is particularly preferable.

  In this case, the polymer polyol is not particularly limited, but contains a hydrophilic polymer and a hydrophobic polymer in a ratio of hydrophilic polymer / hydrophobic polymer = 20/80 to 30/70 (mass ratio). In particular, when lithium imide or the like, which has a small resistance fluctuation due to the environment, is used as an ionic conductive material, the resistance fluctuation due to energization can be effectively suppressed while sufficiently maintaining good environmental fluctuation characteristics. Very good resistance stability can be obtained. The reason is presumed as follows.

  In other words, ion conductive materials such as lithium imide, which have little environmental fluctuations, usually have a resistance to increase in resistance to continuous energization, and such ion conductive materials have a high degree of dissociation and mobility. Both are considered to be high electrolytes, but the dissociation is suppressed by making the surrounding environment hydrophobic, and when polarization progresses, the non-dissociated electrolyte dissociates and supplies ions to increase the resistance value due to energization. It is presumed to be suppressed.

  As the hydrophilic polymer, polyether polyol obtained by addition polymerization of ethylene oxide and propylene oxide, or acrylonitrile-based polymer polyol obtained by graft polymerization of acrylonitrile or acrylonitrile and styrene to the polyol is preferably used.

  When the acrylonitrile-based polymer polyol is used, as the polyol for graft polymerization of acrylonitrile and / or styrene, polyether polyol is preferable from the viewpoint of moisture resistance and the like, and particularly polyether polyol obtained by addition polymerization of ethylene oxide and propylene oxide is preferable. Used. In this case, the ratio of ethylene oxide and propylene oxide added by the polyether polyol obtained by addition polymerization of ethylene oxide and propylene oxide is not particularly limited, but the ratio of ethylene oxide may be 20 to 30% by mass. Preferably, when the ratio of ethylene oxide is too high, the fluctuation range of the resistance value due to the environment tends to increase. Further, those having ethylene oxide added to the terminal are preferably used. Further, the arrangement of ethylene oxide and propylene oxide in the molecular chain is preferably random. The molecular weight of the polyether polyol is not particularly limited, but in the case of bifunctional, the weight average molecular weight is preferably in the range of 80 to 1000, and in the case of trifunctional, the weight average molecular weight is in the range of 300 to 1500. Are preferred.

  Other polyol components can be used in combination with the polymer polyol. Examples of other polyol components include polyether polyols and polyester polyols. Examples of polyether polyols include polyether polyols obtained by addition polymerization of ethylene oxide and propylene oxide. In this case, the polyether polyol obtained by addition polymerization of ethylene oxide and propylene oxide is water, propylene glycol, ethylene glycol, glycerin, trimethylolpropane, hexanetriol, triethanolamine, diglycerin, pentaerythritol, ethylenediamine, methylglucotite, Examples thereof include those obtained by addition polymerization of ethylene oxide and propylene oxide using aromatic diamine, sorbitol, sucrose, phosphoric acid and the like as starting materials.

  In addition, when using polyether polyol as a hydrophilic polymer, it is preferable that the oxygen content rate of the principal chain is 18-36 mass%.

  Next, the hydrophobic polymer is not particularly limited, and examples thereof include polyisoprene polyol, polybutadiene polyol, and polytetramethylene ether glycol.

  The hydrophobic polymer is not particularly limited, but the molecular weight between the hydroxyl groups is preferably 1000 to 4000, and the oxygen content of the main chain is preferably 0.1 to 18% by mass.

  The content ratio of the hydrophilic polymer and the hydrophobic polymer is preferably hydrophilic polymer / hydrophobic polymer = 20/80 to 30/70 (mass ratio) as described above. In this case, the hydrophilic polymer is more than the above ratio. If the amount is too large (the amount of the hydrophobic polymer is small), the resistance value of the obtained polyurethane tends to be low, and the above-described resistance value of the present invention may not be achieved.

  A polyol obtained by condensing an acid component such as adipic acid and a glycol component such as ethylene glycol and ε-caprolactam together with the polyol component as long as the object of the present invention is not impaired. Polyester polyols obtained by ring-opening polymerization, diols such as polycarbonate diol and butanediol, polyols such as trimethylolpropane, and derivatives thereof may be used in combination.

  Next, the isocyanate to be reacted with the polymer polyol is not particularly limited, and known isocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate or derivatives thereof can be used. More specifically, as tolylene diisocyanate or a derivative thereof, crude tolylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 2,4-tolylene diisocyanate and 2 , 6-tolylene diisocyanate mixtures, urea-modified products thereof, burette-modified products, carbosiimide-modified products, urethane-modified products modified with polyols, and the like. Examples of diphenylmethane diisocyanate or its derivatives include diphenylmethane diisocyanate obtained by phosgenating diaminodiphenylmethane or its derivatives. Examples of the derivatives of diaminodiphenylmethane include polynuclear substances such as pure diphenylmethane diisocyanate obtained from diaminodiphenylmethane and polymeric diphenylmethane diisocyanate obtained from the polynuclear body of diaminodiphenylmethane. Derivatives obtained by modifying these diphenylmethane diisocyanates or their derivatives, such as urethane modified products modified with polyols, dimers formed by uretidione formation, isocyanurate modified products, carbociimide / uretonimine modified products, allophanate modified products , Urea-modified products, burette-modified products, and the like, among which urethane-modified products and carbosiimide / uretonimine-modified products are preferably used.

  As these isocyanates, tolylene diisocyanate or a derivative thereof, diphenylmethane diisocyanate or a derivative thereof may be used alone, or two or more thereof may be used in combination. Further, various aliphatic isocyanates such as hexamethylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, or derivatives thereof may be used in combination. The blending amount of the isocyanate is appropriately set according to the number of functional groups of the polyol component and the like, and is not limited thereto, but is usually 0.9 to 1.3, particularly 1 to 1.1 in terms of NCO Index. If the NCO Index is too low, the hardness may be too low and the target hardness for each product may not be obtained. On the other hand, if the NCO Index is too high, the hardness may be too high, The target hardness may not be obtained.

  As described above, the elastic resin material used in the present invention has a resistance value of 11 to 13 [log Ω]. In this case, this resistance value is obtained without adding a conductive agent to be described later. The resistance value is the same as that of the member to be measured, and the measurement condition is the resistance value when a voltage of 1000 V is applied in an environment of 22 ° C. and 55% RH.

  Next, as the conductive agent added to the elastic resin material, an ion conductive material is used. Specifically, tetraethylammonium, tetrabutylammonium, dodecyltrimethylammonium (for example, lauryltrimethylammonium), hexadecyltrimethyl Quaternary ammonium salts such as ammonium, octadecyltrimethylammonium (eg stearyltrimethylammonium), benzyltrimethylammonium, modified fatty acid dimethylethylammonium, lauroylaminopropyldimethylethylammonium, alkali metals such as lithium, sodium, potassium, calcium, magnesium Perchlorate, chlorate, hydrochloride, bromate, iodate, borofluoride, sulfate, alkyl sulfate, such as alkaline earth metal Examples include rubonic acid salts, sulfonic acid salts, and trifluoromethyl sulfate salts. In the present invention, electrolytes having a relatively small resistance fluctuation range due to environmental changes such as lithium imide and potassium imide are preferably used. Lithium imide is particularly preferably used in combination with the specific polyurethane described above.

  The blending amount of the conductive agent is appropriately set according to the conductivity required by the use etc. so that the resistance value of the elastic resin material is in the range of 7 to 9 [log Ω], and is not particularly limited. Usually, it is preferable to set it as 0.003-0.006 mass part with respect to 100 mass parts of said elastic resin materials, and it is especially preferable to set it as 0.004-0.005 mass part. In addition, the measuring method of the resistance value adjusted by addition of a conductive agent is the resistance value when a voltage of 1000 V is applied in an environment of 22 ° C. and 55% RH, as in the above case.

  In the present invention, a curing catalyst for satisfactorily curing the elastic resin material containing the conductive agent can be blended. Curing catalysts include monoamines such as triethylamine and dimethylcyclohexylamine; diamines such as tetramethylethylenediamine, tetramethylpropanediamine and tetramethylhexanediamine; and triamines such as pentamethyldiethylenetriamine, pentamethyldipropylenetriamine and tetramethylguanidine. , Cyclic amines such as triethylenediamine, dimethylpiperazine, methylethylpiperazine, methylmorpholine, dimethylaminoethylmorpholine, dimethylimidazole, dimethylaminoethanol, dimethylaminoethoxyethanol, trimethylaminoethylethanolamine, methylhydroxyethylpiperazine, hydroxyethylmorpholine Alcohol amines such as bis (dimethylaminoethyl) , Ether amines such as ethylene glycol bis (dimethyl) aminopropyl ether, stannous octoate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin thiocarboxylate, dibutyltin thiocarboxylate, dibutyltin dimaleate, dioctyltin markertide, dioctyl Illustrative are organometallic compounds such as tin thiocarboxylate, phenylmercury propionate, lead octenoate, etc., and one or more of these can be used, among which organotin catalysts are particularly preferably used. .

  The elastic resin material constituting the conductive elastic member of the present invention may be an elastomer or a foam body depending on the application, but when foamed polyurethane is used, the cells of the foam material are stabilized. Therefore, it is preferable to add various surfactants and silicone foam stabilizers to the polyurethane composition. As the silicone foam stabilizer, a dimethylpolysiloxane-polyoxyalkylene copolymer or the like is preferably used, and one composed of a dimethylpolysiloxane moiety having a molecular weight of 350 to 15000 and a polyoxyalkylene moiety having a molecular weight of 200 to 4000 is preferably used. . As the molecular structure of the polyoxyalkylene moiety, an addition polymer of ethylene oxide or a co-addition polymer of ethylene oxide and propylene oxide is preferably used, and the molecular terminal thereof is preferably ethylene oxide. Examples of the surfactant include ionic surfactants such as cationic surfactants, anionic surfactants and amphoteric surfactants, and nonionic surfactants such as various polyethers and various polyesters. The blending amount of the silicone foam stabilizer and various surfactants is preferably 2 to 5 parts by mass, more preferably 3 to 4 parts by mass with respect to 100 parts by mass of the polyurethane material.

  Further, the elastic resin material can be blended with appropriate amounts of known additives such as various fillers, color pigments, antioxidants, ultraviolet absorbers, flame retardants, and the like as necessary.

  The elastic resin material constituting the conductive elastic member of the present invention may be an elastomer or a foam body as described above, but is not particularly limited. The body is preferable because the effect of the present invention is remarkable. As a foaming method in this case, a known method can be adopted, for example, a method using a foaming agent such as water, an organic solvent, various alternative chlorofluorocarbons, a method of mixing bubbles by mechanical stirring, or the like can be used. . In addition, the expansion ratio and the bulk density may be appropriately set depending on the application and are not particularly limited. Usually, the expansion ratio is 50 to 200 μm at the maximum cell diameter, particularly 50 to 100 μm, and the bulk density is It is preferably about 0.1 to 0.9 g / mL, particularly about 0.4 to 0.6 g / mL.

  Mixing and heat-curing for producing a member with polyurethane foam are performed by mixing and stirring the above polyol component, isocyanate component, conductive agent, reaction catalyst, and various additive components used as required, and by the above method as necessary. It is preferable to use a method of heat curing after performing an operation such as mixing in a predetermined mold or performing free foaming in a block shape. In addition, a polyol component and an isocyanate component are reacted in advance to prepare a prepolymer having an isocyanate group, and this is prepared by using ethylene glycol, 1,4-butanediol, trimethylolpropane, a polyol having a molecular weight of about 400 to 5000, and the like. It is also possible to use a prepolymer method in which a chain extender is used for curing.

  The conductive elastic member of the present invention is mainly composed of the elastic resin material whose resistance value is adjusted by adding the ionic conductive substance, and has various forms such as a roller shape, a belt shape, a blade shape, and a drum shape. Are used as charging members, developing members, transfer members, intermediate transfer members, toner supply members, cleaning members, etc. for image forming apparatuses such as copiers and printers. It is particularly suitable as a transfer member.

  If the specific example using the electroconductive elastic member of this invention as a transfer member is illustrated, the image forming apparatus shown in FIG. 1 can be illustrated. That is, in FIG. 1, reference numeral 1 denotes a drum-shaped photoconductor that rotates in the direction of the arrow in the figure. The photosensitive member 1 is charged by a primary charger 2, and then the exposed portion is uncharged by image exposure 3 to form an electrostatic latent image on the photosensitive member 1. Further, the electrostatic latent image is developed by a developing device. As a result, a toner image is formed on the photoreceptor 1. Then, a transfer roller (transfer member) 25 abuts on the photoreceptor 1 on which the toner image is formed, and a recording medium 24 such as paper is fed from the paper feed cassette 9 to the nip portion, and at the same time, secondary transfer is performed. A bias is applied to the transfer roller 25, and the toner image is transferred from the photoreceptor 1 to the recording medium 24. The recording medium 24 is further introduced into the fixing device 15, and the toner image on the recording medium 24 is heated and fixed. It becomes. After the toner image is transferred to the recording medium 24, the transfer residual toner on the surface of the photoreceptor 1 is removed by the cleaning blade 14 to return to the initial state and prepare for the next image formation.

  The conductive elastic member of the present invention is suitably used as the roller-shaped transfer member 25 described above. Thus, when it is set as a roller-shaped member, normally, the elastic body which consists of the said elastic resin material is shape | molded around metal cores, and it forms in a roller shape. In this case, as a method of forming the elastic body around the core metal, the core metal is previously disposed in the mold and the elastic body material is cast and cured, or after the elastic body is molded into a predetermined shape A method of bonding can be used. In either case, an adhesive layer can be provided between the cored bar and the elastic body as necessary, and an adhesive made of a conductive paint, a hot melt sheet, or the like can be used. The method of molding the conductive elastic member of the present invention includes a method of cutting into a predetermined dimension by cutting from a block, a method of cutting to a predetermined dimension from a block, a method of casting to a predetermined shape, as described above, Alternatively, a method of appropriately combining these methods can be used.

  In addition, the conductive elastic member of the present invention is excellent in non-contaminating property, and does not contaminate a mating member such as a photosensitive drum even if it remains in close contact with the photosensitive drum for a long time. However, it is also possible to form a skin layer on the surface of the elastic body made of the elastic resin material according to its use. Furthermore, the conductive elastic member of the present invention may be mainly composed of an elastic body made of the above elastic resin material, and it is possible to add a publicly known configuration such as using an appropriate core material according to its use or shape. There is no problem.

EXAMPLES Hereinafter, although an Example is shown and this invention is demonstrated more concretely, this invention is not restrict | limited to the following Example.
The components shown in Table 1 were mixed while being foamed by mechanical stirring, and this mixture was cast into a mold centered on a metal shaft having a diameter of 6 mm, cured by heating at 90 ° C. for 3 hours, and a diameter of 16.5 mm. An ureta foam roller having a length of 215 mm was obtained. Details of each component shown in the table are as follows, and each roller has a resistance value of 7.9 [logΩ] (at 22 ° C., 55% RH, 1000 V applied) by adding an ionic conductive agent. It was adjusted. In addition, the compounding quantity in a table | surface is a weight part.

[Polymer polyol]
Hydrophobic polyol polyisoprene polyol (molecular weight between OH groups: about 2500)
Polyether polyol having propylene oxide and ethylene oxide randomly added to hydrophilic polyol glycerin and having a functional group number of 3 and a weight average molecular weight of 5000 (oxygen content of main chain: 29% by mass).
[Foam stabilizer]
Silicone foam stabilizer A silicone foam stabilizer having an OH value of 32 mgKOH / g, which is a dimethylpolysiloxane-polyoxyalkylene copolymer.
[Pigment]
Black colorant A black colorant having an OH value of 45 mgKOH / g obtained by dispersing a black pigment in a polyol.
[catalyst]
Dibutyltin dilaurate.
[Ion conductive agent]
Lithium imide [isocyanate]
Modified MDI
It is a mixture of diphenylmethane diisocyanate, urethane-modified diphenylmethane diisocyanate, and carbosiimide-modified diphenylmethane diisocyanate, and the isocyanate content is 26.3 mass%.

For each of the obtained rollers, the resistance value fluctuation range (environment fluctuation range) due to environmental changes, the resistance value increase (continuity increase) due to continuous energization, and the polyurethane foam resistance value were measured and evaluated by the following methods. The results are shown in Table 1.
[Environmental change]
Between each shaft / roller surface under the L / L environment (10 ° C., 15% RH), N / N environment (22 ° C., 55% RH), and H / H environment (28 ° C., 85% RH). A resistance value was measured by supplying a current of 10 μA, and the difference between the maximum value and the minimum value was converted into a fluctuation range after logarithmically converting the measured resistance value. Each roller is prepared so as to exhibit a resistance value of about 10 ^7.9 Ω under an N / N environment (22 ° C., 55% RH) by blending a conductive agent at the time of manufacture.
[Energization rise]
While the roller is driven to rotate on a φ30 mm aluminum drum rotating at 30 rpm, a current of 10 μA is continuously energized for 50 hours, and the initial resistance value and the resistance value after 50 hours are converted into a logarithm, and the difference between this and the energization increase value did. Moreover, the change of the resistance value is shown as a graph in FIG.
[Resistance value of polyurethane foam]
The resistance value of a roller formed without adding a conductive agent (lithium imide) was measured by applying a voltage of 1000 V under an N / N environment (22 ° C., 55% RH).

＊１：図２に示したグラフの通り、比較例１〜３の各ローラは、いずれも３０時間以内に抵抗値が測定機器の測定限界（８．８［ｌｏｇΩ］）に達してしまい。５０時間後の抵抗値を測定することができなかった。

* 1: As shown in the graph of FIG. 2, the resistance values of the rollers of Comparative Examples 1 to 3 all reached the measurement limit (8.8 [logΩ]) of the measuring instrument within 30 hours. The resistance value after 50 hours could not be measured.

  As shown in Table 1, the roller of the present invention in which the ratio of the hydrophilic polymer to the hydrophobic polymer in the polymer polyol component was adjusted to set the electrical resistance of the polyurethane foam to 11 to 13 [log Ω] The environmental fluctuations and current fluctuations of the values are small, uniform resistance values can be obtained stably, good performance is stably exhibited, and they are suitably used as conductive elastic members for image forming apparatuses. Was confirmed.

1 is a schematic diagram illustrating an example of an image forming apparatus using an intermediate transfer member. It is a graph which shows the electricity supply raise of the resistance value of each roller in an Example and a comparative example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 14 Cleaning blade 15 Fixing device 2 Charging device 24 Recording medium 25 Transfer roller 4 Developing device

Claims (11)

A conductive elastic member for an image forming apparatus mainly composed of an elastic body in which an ion conductive substance is added to an elastic resin material and the resistance value is adjusted to 7 to 9 [logΩ],
A conductive elastic member for an image forming apparatus, wherein a resin having an electric resistance of 11 to 13 [log Ω] is used as the elastic resin material.   The conductive elastic member for an image forming apparatus according to claim 1, wherein the ionic conductive substance contains lithium imide.   The conductive elastic member for an image forming apparatus according to claim 1, wherein the elastic resin material is polyurethane.   The elastic resin material is a polyurethane obtained by reaction-curing an isocyanate component and a polymer polyol component, and the ratio of hydrophilic polymer to hydrophobic polymer in the polymer polyol component is hydrophilic polymer / hydrophobic polymer = The conductive elastic member for an image forming apparatus according to claim 3, which is 20/80 to 30/70.   The conductive elastic member for an image forming apparatus according to claim 4, which contains acrylonitrile-based polymer polyol as the hydrophilic polymer.   The conductive elastic member for an image forming apparatus according to claim 4, wherein the hydrophilic polymer contains a polyether polyol.   The conductive elastic member for an image forming apparatus according to claim 6, wherein the oxygen content of the main chain in the hydrophilic polymer is 18 to 36% by mass.   The conductive elastic member for an image forming apparatus according to any one of claims 4 to 7, wherein the hydrophobic polymer contains a polyol having a main chain having a molecular weight between hydroxyl groups of 1000 or more.   The conductive elastic member for an image forming apparatus according to claim 8, wherein the oxygen content of the main chain of the hydrophobic polymer is 0.1 to 18% by mass.   The conductive elastic member for an image forming apparatus according to claim 1, which is a transfer member that transfers a toner image from a photosensitive drum to a recording medium. The electroconductive elastic member according to claim 10 is used as a transfer member for performing the transfer operation in an image forming apparatus for transferring a toner image formed on a photosensitive drum to a recording medium to form an image on the recording medium. An image forming apparatus.

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