JP2000255817A - Conductive belt and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture a conductive belt on high surface smoothness and a mold surface releasing property by slantingly dispersing a conductive substance so that the content of the conductive substance in a protection layer becomes higher from the conductive layer side toward the surface side. SOLUTION: A conductive belt 10 is formed with a protection layer 11 on a conductive layer 12 an ion conductive substance, conductive filler, containing conductive carbon, and the like. The protection layer 11 contains binder such as acryl resin, polyester resin, nylon resin, or fluororesin, and a conductive substance A, the content of the conductive substance A in the protection layer 12 is slantingly dispersed in the layer 12, so as to become higher from the face 11b on the conductive layer 12 side toward the surface 11a. Hereby, the conductive belt 10 of high surface smoothness and a surface mold releasing property can be easily manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive belt, and more particularly, to a conductive belt suitably used for a transfer device and a sheet conveying member in an image forming apparatus such as an electrophotographic apparatus.

[0002]

2. Description of the Related Art A conductive belt is used for a belt transfer device and a sheet conveying belt member used in an image forming apparatus such as an electrophotographic apparatus. The conductive belt for such an application not only has a predetermined electric resistance value but also has characteristics suitable for various mechanisms such as a device to be used. Conventionally, conductive belts are made of silicon rubber, NB
R, H-NBR, CR, UR, EPDM, ECO, N
A general rubber material such as R, FKM or IIR is used as a base material, and a filler-based conductive substance, for example, a general conductive carbon, a conductive metal oxide, a carbon fiber, and a carbon bead are added to the base material. The electric resistance value is adjusted to a desired range.

When a conductive belt is used as a transfer belt, a protective layer made of, for example, a fluorine resin is provided on the conductive layer in order to prevent toner from remaining and improve blade cleaning properties. In many cases, release and smoothness are imparted to the surface. Conventionally, when a protective layer is provided on a conductive layer, after forming the conductive layer, the conductive layer is coated by a spray coating, an electrostatic coating, or a roll coater method, a flow coat method, a dip coat method, or the like. It is formed by applying a liquid and curing by heating.

[0004]

In some cases, the protective layer contains a conductive substance in order to keep the electric resistance of the conductive belt within an appropriate range. However, usually, since the conductive substance has a higher specific gravity than the binder or the like forming the layer, when the protective layer is formed by the above-mentioned method of coating or the like, the dispersion of the conductive substance in the protective layer is reduced. The concentration becomes non-uniform, and the conductive substance tends to be unevenly distributed on the interface side between the protective layer and the conductive layer, away from the surface of the protective layer,
It becomes difficult to control the surface resistance. As a result, the conductivity of the conductive belt becomes insufficient, and when used as a transfer belt, smears on the transfer belt due to residual untransferred toner and poor transfer due to uneven resistance of the transfer belt cause white spots in an image. May occur. By increasing the content of the conductive substance in the protective layer, it is conceivable to improve the conductivity.However, as the content of the conductive substance is increased, the effect of reinforcing the belt increases, and the rigidity of the protective layer increases. It tends to become brittle as it becomes higher, and the elasticity of the belt becomes insufficient or becomes brittle, resulting in a decrease in durability.

[0005] An object of the present invention is to solve the above problems. That is, an object of the present invention is to provide a conductive belt having sufficient conductivity and high surface smoothness and surface releasability, and a method for easily manufacturing the conductive belt. Further, the present invention provides a conductive belt that improves the transferability of an image when used as a transfer belt of an image forming apparatus and reduces image defects due to transfer failure, and easily manufactures the conductive belt. The purpose is to provide a way to obtain.

[0006]

As a result of intensive studies, the present inventors have found that the above problems can be solved by controlling the distribution of a conductive substance in a protective layer.
Based on this finding, the present invention has been completed. That is, the present invention provides a conductive belt and a conductive belt having a protective layer formed thereon, wherein the protective layer contains a conductive substance,
The conductive belt is characterized in that the conductive material is inclined and dispersed such that the content of the conductive material in the protective layer increases from the conductive layer side toward the surface side. In the conductive belt of the present invention, since the conductive material is more distributed in the vicinity of the surface in the protective layer, the conductivity of the surface can be kept high with a low blending amount.

It is preferable that the conductive layer contains an ion conductive substance and carbon black. Further, the conductive layer is preferably made of an elastomer having a urethane bond and / or a urea bond, and the average ratio of the urethane bond to the urea bond in the elastomer is 5: 9.
It is preferably from 5 to 95: 5. Further, the elastomer is preferably formed from an amine compound, a polyol, and an isocyanate compound. The thickness of the conductive belt is preferably 20 to 500 μm, and the average variation of the thickness is preferably within 3% of the thickness. More preferably, the thickness of the conductive belt is 50 to 150 μm.
m,

Further, the present invention provides a method for forming a protective layer containing a binder and a conductive substance into a cylindrical mold, rotating the mold, and heating the mold so that the inner wall of the mold is heated. A protective layer forming step of forming a protective layer, and a conductive layer forming solution containing a conductive layer forming material is charged into the mold having the protective layer formed on the inner wall surface, and the mold is rotated and heated. A conductive layer forming step of forming a conductive layer on the protective layer, wherein the specific gravity of the conductive substance is larger than the specific gravity of the binder. This is a method for producing a belt. In the method for producing a conductive belt according to the present invention, in the step of forming the protective layer, a conductive substance having a larger specific gravity than the binder is used, and the conductive substance is distributed more on the inner wall surface side of the mold by the action of centrifugal force. I have.

The solubility parameter of the protective layer forming solution and the solubility parameter of the conductive layer forming solution may differ by one or more, and may be incompatible.
Further, in the conductive layer forming step, it is preferable that at least a urethane bond and a urea bond are formed by a reaction of a material forming the conductive layer. Preferably, the method further includes a step of polishing the back surface of the conductive layer.

[0010]

FIG. 1 shows an example of a schematic sectional view of a conductive belt according to the present invention. The conductive belt 10 of FIG.
In this configuration, the protective layer 11 is formed on the conductive layer 12. The protective layer 11 contains the conductive substance A, and the content of the conductive substance A in the protective layer 12 increases from the surface 11b on the conductive layer side toward the surface 11a. Dispersed in the protective layer. Therefore, the conductive belt 10 has high conductivity. In addition, the conductive belt 10 does not need to excessively contain a conductive substance in order to improve the conductivity of the conductive belt 10, and thus the conductive belt 10 has appropriate rigidity and elasticity. In the conductive belt 10 of FIG. 1, most of the conductive substance A is on the surface 11a of the protective layer.
However, the present invention is not limited to this embodiment. For example, the concentration of the conductive material A is proportionally increased from the surface 11b on the conductive layer side to the surface 11a. And an exponentially high aspect. In addition, the concentration does not need to be continuously increased, but may be discontinuously (stepwise) increased.

Although the preferred range of the thickness of the conductive belt 10 varies depending on the application and the like, when the conductive belt is used as a transfer belt, the thickness is 50 to 3000 μm.
Is preferably, and more preferably 10 to 1000 μm. If the thickness is less than the above range, permanent elongation is likely to occur, and the transferred image is likely to shift with time. On the other hand, if the thickness exceeds the above-mentioned range, the shape followability with respect to the driving roller and the like tends to be reduced. Also,
When used for the same purpose, the average variation of the thickness is preferably 3% or less of the thickness, more preferably 2% or less. If the variation of the thickness exceeds 3%, the deviation of the transferred image tends to increase when the colors are superimposed.

When the conductive belt 10 is used as a transfer belt, its hardness is preferably 70 to 80 as measured by a JIS-A hardness meter. When used for the same purpose, the 100% belt elongation modulus is 5%.
It is preferably from 0 to 300 kgf / cm ² . In addition, 1
The 00% belt elongation modulus can be measured by cutting a belt into a dumbbell shape and using a tensile tester.

When a conductive belt is used as the transfer belt, the cleaning property when blade cleaning the toner residue from the surface of the belt becomes high, so that the belt preferably has high surface smoothness, and its surface roughness Rz Preferably, the value is 10 μm or less on average at 10 points.
It is more preferable that it is not more than μm.

The electric volume resistivity of the conductive belt 10 is preferred.
The suitable range varies depending on the application, etc.
When 0 is used as the transfer belt, the electric volume resistivity is
10 ^Four-10¹²Ω · cm, preferably 10⁸~ 1
0¹¹More preferably, it is Ω · cm. Electric volume resistivity
Is within the above range, even when a high voltage is applied,
Resistance can be maintained. Surface resistance of conductive belt
Rate is 10^Four-10¹⁵Ω / □, preferably 10
^Ten-10¹²Ω / □ is more preferable. Also, conductive
The electric volume resistance of the layer 12 is 10^Four-10¹²Ω · cm
Preferably 10⁸-10¹¹Ω · cm
More preferred. About the electric volume resistivity of the protective layer 11
Means that the electric volume resistivity of the conductive belt 10 is within the above range.
Is not particularly limited as long as it is higher than the conductive layer.
It preferably exhibits a gas volume resistivity. Electric volume resistivity is
The content of the conductive substance contained in the conductive layer and the protective layer,
Adjust centrifugal force, binder viscosity and concentration during rotational molding
Can be adjusted to a preferred range by
You.

The protective layer 11 contains a binder and a conductive substance. Acrylic resin,
Thermoplastics such as polyester resin, nylon resin, fluorine resin, imide resin, melanin resin, urethane resin, urea resin, polyethersulfone resin, silicone resin, styrene resin, polycarbonate resin, vinyl chloride resin, nitrile resin, SBR, NBR rubber, etc. Resins, thermosetting resins and the like can be used. In particular, it is preferable to use polyimide, PVdF, or the like because a protective layer having high surface smoothness and surface release properties is obtained.

The conductive material contained in the protective layer 11 is not particularly limited, and may be any known conductive material, as long as it has a specific gravity larger than the specific gravity of the binder used in combination, depending on the purpose. You can choose from substances. For example, conductive carbon, black carbon,
Examples thereof include metal oxides such as tin oxide and zinc oxide, and inorganic fillers such as potassium titanate, nickel, Al powder, and carbon resin. These may be used alone, or may be used in combination. By using them together, the conductivity and the dielectric property may be adjusted and controlled. Above all, it is preferable to use doped tin oxide together with zinc oxide or the like having a high dielectric property, since the holding power of the toner during transfer can be increased and image defects can be further suppressed. Although the content of the conductive substance in the protective layer 11 varies depending on the use of the conductive belt and the type of the conductive substance to be used, the content is preferably 1% by weight to 50% by weight, and preferably 5% by weight to 30% by weight. More preferably, it is contained by weight%.

The thickness of the protective layer 11 varies depending on the use of the conductive belt. However, when the conductive belt of the present invention is used as a transfer belt, the thickness, the deflection,
And from the viewpoint of tear strength and the like, usually 10 to 500
μm, preferably 20 to 150 μm, more preferably 20 to 50 μm.

The conductive layer 12 preferably contains a binder and a conductive substance. As the binder, a usual matrix material can be used, for example, an elastomer material such as polyurethane, epichlorohydrin rubber, nitrile rubber, styrene butadiene rubber, liquid silicone rubber; polyphenylsulfone, polysulfone, polyethersulfone, polyester, Engineering plastic materials such as polyacetal, polyarylate, polyamide, polycarbonate, polyphenylene ether, polyetherimide, polyamideimide, polyimide, and polyphenylene sulfide; poly (vinylidene fluoride) (PVdF), polytetrafluoroethylene (PTF)
E), a fluororesin material such as polyhexafluoropropylene (PHFP); or the like can be used alone or in combination. In addition, a Teflon-based or silicone-based dispersed release material can also be used.

The binder of the conductive layer 12 contains a urethane bond (—NHCOO—) or a urea bond (—NH
An elastomer having CONH-) is preferable because permanent elongation caused by belt stretching or the like is reduced, and appropriate elasticity is exhibited as a belt, and belt meandering can be prevented and walk control can be performed. In particular, it is more preferable to use an elastomer having both bonds from the same viewpoint. The elastomer having a urethane bond and a urea bond can be produced by blending an amine compound, a polyol, and an isocyanate compound with a catalyst, if desired, and reacting them. Examples of the polyol include a polyether polyol having a polyhydroxyl group at a terminal, a polyester polyol, and a polyether polyol which is a copolymer thereof. In addition, general polyols such as polyolefin polyols such as polybutadiene polyol and polyisoprene polyol, and polyol prepolymers obtained by polymerizing ethylenically unsaturated monomers in the polyol can be used.

The amine compound is preferably a polyamine which is a compound having two or more amino groups in one molecule, for example, aliphatic amines such as hexamethylenediamine, 2,5-dimethylpiperazine, triethylenediamine, biphenyldiamine, and the like. Aromatic diamines such as 3,3'-dichlorobenzidine, bis (aminophenyl) ether and p-amino-aniline can be used.

As the isocyanate compound, 1
Polyisocyanate compounds having two or more isocyanate groups in the molecule are preferable. For example, toluene diisocyanate (TDI), crude TDI, 4,4-diphenylmethane diisocyanate (MDI), crude MDI, isophorone diisocyanate, various modified MDI, carbon ~
An aliphatic isocyanate of 18, an alicyclic polyisocyanate having 4 to 15 carbon atoms and a mixture or modified product of these polyisocyanates, for example, a prepolymer obtained by partially reacting with a polyol or a diamine can be used.

As the catalyst to be used if desired, an organometallic compound or the like generally used as a catalyst can be used. For example, butyltin laurate, octylzinc, sodium acetate, alkoxides of alkali metals or alkaline earth metals, phenoxides, tertiary amines (for example, triethylamine, triethyldiamine, N-
Methylmorpholine, dimethylaminomethylphenol, etc.), quaternary ammonium salts, imidazoles such as nickel acetyl acetate and nickel diacetylacetonate.

The average ratio of urethane bonds to urea bonds in the elastomer is preferably from 5:95 to 95: 5, more preferably from 30:70 to 70:30. The average ratio of urethane bonds to urea bonds can be determined by measuring the infrared absorption spectrum of the conductive layer and determining the area ratio of the absorption peak due to each bond. The urethane bond in the elastomer can be adjusted by the amount of the polyol and the isocyanate, and the urea bond can be adjusted by the amount of the polyamine compound and the isocyanate. Therefore, by selecting the amounts of the polyol, amine compound, isocyanate compound, and the like, the average ratio of urethane bonds to urea bonds in the obtained elastomer can be adjusted. In particular, it is desirable to use diisocyanate as a curing agent for a polyol or an amine compound to adjust the reactivity ratio to 0.95 to 1.10, preferably 1.03 to 1.07, and co-crosslink.

Examples of the conductive substance contained in the conductive layer 12 include an ionic conductive substance, a conductive filler, and a conductive carbon. Examples of ion conductive materials include lauryl trimethyl ammonium, stearyl trimethyl ammonium, octadecyl trimethyl ammonium,
Dodecyltrimethylammonium, alcohol-modified fatty acid, dimethylammonium perchlorate, halogen salt, borofluoride, sulfate, sulfonate, cationic surfactants such as quaternary ammonium salts such as ethosulfate salt, Anionic surfactants such as aliphatic sulfonic acids, higher alcohol sulfates, higher alcohol ethylene oxide addition sulfates, higher alcohol phosphates, higher alcohol ethylene oxide addition phosphates, and nonionic surfactants such as various betaines Agents, higher alcohols ethylene oxide, polyethylene glycol fatty acid esters, polyhydric alcohol fatty acid esters, etc., nonionic antistatic agents such as antistatic agents, Li
ClO ₄ , LiCF ₃ SO ₃ , NaClO ₄ , LiAs
Examples thereof include metal salts such as F ₆ , LiBF ₄ , NaSCN, KSCN, and NaCl, and electrolytes such as ammonium salts and phosphates. Examples of the conductive carbon black include known conductive carbons such as Ketjen black, furnace black, and acetylene black.

The content of the conductive substance in the conductive layer 12 varies depending on the use of the conductive belt and the type of the conductive substance to be used, but the content is preferably 0.01% by weight to 50% by weight. 1% to 25% by weight is more preferred. In particular, when the above-mentioned elastomer having a urethane bond and a urea bond is used as a binder of the conductive layer, 0.001 to 100 parts by weight of the elastomer is used.
When 5 parts by weight, more preferably 0.01 to 2 parts by weight of the ionic conductive material is contained, the electric volume resistivity of the conductive layer can be easily adjusted to 10 ⁴ to 10 ¹² Ω · cm. When it is desired to impart higher conductivity to the conductive layer, 0.01 to 50 parts by weight based on 100 parts by weight of the elastomer.
The electric resistivity can be reduced by adding a conductive material in an amount of 0.1 to 20 parts by weight, preferably 0.1 to 20 parts by weight.

The conductive material contained in the conductive layer 12 may be used alone or in combination of two or more. If both the ionic conductive material and the conductive carbon black are contained,
It is preferable because the conductivity can be suppressed from fluctuating due to environmental changes. As a combination of the ion conductive substance and carbon black, a combination of an alkyl ammonium salt and Ketjen black, a combination of lithium perchlorate and furnace black, and a combination of sodium perchlorate and acetylene black are preferable. In the above combination, it is preferable to contain 0.001 to 2% by weight of the ion conductive substance and 0.1 to 50% by weight of the conductive carbon black.

The conductive belt of the present invention can be easily manufactured by a centrifugal molding method. FIG. 2 shows an example of a flow of a method of manufacturing a conductive belt of the present invention using a centrifugal molding method. First, a solution containing a raw material for a protective layer is poured into a cylindrical mold 13 (FIG. 2A). The liquid is dissolved in an organic solvent or the like,
It is a liquid in which at least a binder is dissolved or dispersed, and a conductive substance is further dispersed. The binder and the conductive material contained in the liquid are combined so that the specific gravity of the conductive material is greater than the specific gravity of the binder. The cylindrical mold 13 is rotatable around the center of a circle by a drive motor or the like. In addition, the mold 13
Are arranged in a heating furnace or the like, and can be heated simultaneously with rotation. Next, while rotating the mold 13,
Upon heating, a protective layer 11 is formed on the inner wall of the mold 13 (FIG. 2b). Since the specific gravity of the conductive substance put into the mold 13 is larger than the specific gravity of the binder, the conductive substance is more concentratedly distributed on the inner wall surface side by the action of the centrifugal force.

The raw materials used for forming the protective layer 11 are as follows:
A monomer for the binder may be used, and a curing reaction may be performed by heating during centrifugal molding to form a protective layer. In the present invention, since the protective layer is formed first, in the formation by the conventional coating process, the selection of the material is limited due to the limitation of the heating temperature and the like. A high polyimide resin or a fluorine emulsion resin can be used, and the range of material selection can be widened.

When the inner wall surface of the cylindrical mold 13 is lined with, for example, silicone resin to make the surface highly smooth, the surface of the protective layer 11 can be mirror-finished. As a result, a conductive belt having an Rz value of 1 μm or less and having high surface smoothness can be manufactured without performing a surface polishing treatment or the like thereafter. Furthermore, it is possible to suppress a variation in film thickness during molding and to suppress axial deflection and the like during molding.

Next, a solution containing a material for forming a conductive layer is poured into the mold 13 having the protective layer 11 formed on the inner wall surface (FIG. 2C). The liquid containing the forming material is, for example,
It is a solution or the like in which a thermoplastic material or a thermosetting material serving as a binder of the conductive layer is dissolved or dispersed in an organic solvent or the like, and further, a conductive substance is dispersed. When the mold 13 is rotated and heated, the conductive layer 1 is formed on the protective layer.
2 are formed (FIG. 2d). When the liquid contained in the liquid is a thermoplastic material, up to a temperature exceeding its melting point,
In the case of a thermosetting material, it is preferable to form the conductive layer by heating to a temperature exceeding the curing temperature, since the adhesion between the conductive layer and the protective layer is improved. In addition, when a protective layer is formed by a conventional coating process, if an incompatible material having a solubility parameter different from the binder of the conductive layer by one or more is used as the binder of the protective layer, the adhesion between the protective layer and the conductive layer is reduced. However, by adjusting the heating temperature as described above, it is possible to bond the fused interlayer even with an incompatible material, and between the protective layer and the conductive layer.
Sufficient adhesion can be provided.

As a material for forming the conductive layer, a polyol compound, an amine compound, and an isocyanate compound are contained in a liquid, and while the mold is rotated and heated, the compound is reacted to form a urethane bond and a urea bond. The formation is preferable because a conductive layer made of an elastomer having appropriate elasticity and having high adhesion to the protective layer and reduced permanent elongation can be produced.

After the conductive layer 12 is formed, it is cooled and then released to obtain a conductive belt 10 having a two-layer structure (FIG. 2E). Before and after the release, a step of performing a high-temperature heat treatment to complete a curing reaction or the like may be performed.

Further, it is preferable that the back surface 12a of the conductive layer 12 is polished. On the back surface 12a of the conductive layer 12, unreacted monomers, low molecular oligomers, impurity components attached to the mold and the like remain, bubbles caused by air entrainment during centrifugal molding, traces of evaporation of water, and raw material components May be traced or dropped. Therefore, by polishing the back surface 12a, smoothing the unevenness of the back surface 12a, and removing foreign matters and the like, a more uniform and high-quality conductive belt can be manufactured. In addition, there may be a case where the thickness varies due to bias of reactivity or the like at the time of centrifugal molding, or the thickness of the conductive belt needs to be adjusted according to the application. In that case, the surface 11a of the protective layer 11 can be polished. However, for example, when high surface smoothness such as a transfer belt is required, it is necessary to perform wet polishing, and the processing is restricted. Or the need to perform a surface property inspection. If the back surface 12a is polished, there is no such restriction, and even with an easy polishing method such as dry polishing, the thickness can be made uniform and the thickness can be reduced. As a result, adjustment of belt rigidity and suppression of resistance unevenness can be achieved. It is possible. Also,
For example, the back surface can be polished into strips at regular intervals for the purpose of preventing belt meandering as well as simply adjusting the thickness.

When the obtained conductive belt is used as a transfer belt, the thickness of the conductive belt is 50 to 300.
The back surface 12a is preferably polished so that the thickness is 0 μm and the variation in thickness is within 3%, more preferably within 1% of the thickness. For example, when the thickness is 500 μm, the back surface is preferably polished to have a thickness variation of less than 15 μm, more preferably less than 5 μm. The surface roughness of the back surface is not particularly limited, and the back surface may be polished so as to be in a preferable range according to the use or the like. For example, the Rz value can be set to 5 μm or more for the purpose of securing the friction coefficient of the back surface.

FIG. 3 is an example of a schematic sectional view of an electrophotographic full-color image forming apparatus using the conductive belt 10 of the present invention as a transfer belt. Conductive belt 10
Is stretched by rolls 60 to 63 so that the protective layer 12 faces the photoconductor 1 and the recording paper 24, and is driven in the direction of the arrow by drive rolls 60 and 61. The photoreceptor 1 is rotatably supported by an outer frame of the image forming apparatus. First, the photoreceptor 1 is uniformly charged by the charging device 2, and is imagewise exposed at a position facing the exposure device 3. As a result, a latent image is formed on the surface of the photoconductor 1. When the photosensitive member 1 rotates and the latent image formed on the photosensitive member 1 comes to a position facing the developing device 41, the latent image is developed by the toner stored in the developing device 41, and the latent image is developed. An image is formed thereon. Then, the photoconductor 1
The toner image formed thereon is transferred to the surface of the conductive belt 10 at the nip between the roll 63 and the photoconductor 1 by applying a bias from the power supply 30.

Thereafter, after the toner or the like remaining on the surface of the photosensitive member 1 is removed by the cleaner 14, the charging device 2
Is repeated three times, and the toner images developed by the developing devices 42 to 44 are transferred onto the conductive belt 10 in a superimposed manner. The color toner image on the conductive belt is transferred onto the conveyed recording paper 24 at the nip between the transfer roll 25 and the roll 62 by applying a bias from the power supply 29. The conductive belt 10 has surface smoothness and surface release properties, and also has high surface conductivity, so that the toner image formed on the conductive belt 10 is transferred to recording paper at a high transfer rate.

The conductive belt of the present invention is a color copying machine,
It can be used for intermediate transfer belts of color printers, monochrome printers, monochrome copying machines, and transport belts.

[0038]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited to the following examples. <Example 1> Formation of protective layer 100 parts by weight of a PVdF-PTFE copolymer (specific gravity 1.76) as a binder was dissolved in a solvent (toluene / acetylene = 50/50% by weight), and 15% by weight was dissolved. PV
A dF-PTFE solution was prepared. To this solution, 7 parts by weight of antimony-doped tin oxide (manufactured by Catalyst Kasei; specific gravity: 4.6) was added as a conductive substance, and dispersed by a paint shaker for 30 minutes. This liquid is introduced into a rotor (inner diameter φ150 mm, depth 400 mm) of a centrifugal molding machine, and the rotor rotation speed is 3000 rpm and the rotor temperature is 120.
The film was dried at 15 ° C. for 15 minutes to form a protective layer having a thickness of 23 μm. Incidentally, the inner wall side surface of this rotor was subjected to hard chrome plating.

Formation of Conductive Layer As a polyol, 100 parts by weight of a polyether polyol obtained by adding propylene oxide and ethylene oxide to glycerin (“Exenol 82819”, manufactured by Asahi Glass Co., Ltd .; molecular weight 5000), and hexamethylene diamine as an amine compound 2 parts by weight, as an isocyanate compound, 18 parts by weight of urethane-modified 4,4-diphenylmethane diisocyanate ("Sumidur PF", manufactured by Sumitomo Bayer), 1 part by weight of 1,4-butanediol, and dibutyltin urarate as a catalyst 0.01 parts by weight, tetrabutylammonium perchlorate as a conductive substance, 0.5 parts by weight, conductive carbon black (“FW
200 "(manufactured by Degussa Co., Ltd.) and 18 parts by weight were each dissolved or dispersed in a MEK-toluene solvent to obtain a reactive mixture. The reactive mixture is charged into the rotor of the centrifugal molding machine having the protective layer formed thereon, and rotated at 300 rpm.
It was baked for 15 minutes under the condition of 100 degrees. A conductive layer was formed on the protective layer, and an endless conductive belt having a thickness of about 167 μm was obtained.

The obtained conductive belt was released from the mold and heated at 140 ° C.
For 6 hours to complete the reaction. Next, the back surface of the conductive layer was subjected to a dry polishing treatment to make the thickness of the conductive layer 80 μm. When the thickness variation was measured, the average variation was 3 μm. Observation of the protective layer with an SEM revealed that tin oxide, which is a conductive substance, was mainly distributed on the surface of the protective layer. When the infrared absorption spectrum of the conductive layer was measured, the average ratio of urethane bonds to urea bonds was 30:70. The electric volume resistivity of the obtained conductive belt was measured using “Hiresta HRS” (manufactured by Mitsubishi Chemical Corporation) in accordance with JIS-K6911. × 10
It was ⁸ Ω · cm. Similarly, when the surface resistivity was measured, it was 7 × 10 ⁹ Ω / □. Further, the modulus strength was reduced to 130 to 140 kgf / cm ² .

Next, the obtained conductive belt was cut into a predetermined length and used as a transfer belt of an image forming apparatus having a structure shown in FIG. The conductive belt was stretched around rolls 60 to 63 with a tension of 12 kg applied. The belt was rotated at a peripheral speed of 26 cm / sec at an applied voltage of 2 KV for 48 hours. Thereafter, the electric volume resistivity and the surface resistivity were measured in the same manner as described above, but no change was observed.

Next, after the image formation of the color test pattern was continuously performed on 300 sheets of recording paper, continuous operation was performed only for 200 hours without recording, and then the operation was repeated for 30 hours.
The cycle of forming an image on zero recording paper was repeated, and the image was evaluated from the start of the test to the lapse of 2000 hours. The image evaluation was performed on the image formed on the 300th recording sheet in each cycle, and it was confirmed by microscopic observation whether or not the toner image had a misalignment and the occurrence of a hollow image. Further, the elongation percentage of the transfer belt after 2000 hours was calculated according to the following equation 1. Formula 1 Elongation rate (%) = {(perimeter length before test end)-(perimeter length before test start)} (perimeter length before test start) × 100 It is shown in FIG.

<Example 2> As a binder for the protective layer,
Polyethersulfone (specific gravity: 1.57) was dissolved in a solvent, dimethylacetamide, to prepare a 20% by weight polyethersulfone solution. To this solution, 7 parts by weight of conductive carbon ("Ketjen Black 600JD", manufactured by International; specific gravity 1.80) was added.
The mixture was dispersed by a paint shaker for 30 minutes. Using the same centrifugal molding machine as in Example 1, the rotor rotation speed was 1500
It was baked for 30 minutes under the conditions of rpm and a rotor temperature of 120 ° C. to form a 50 μm-thick protective layer. Subsequent operations were performed in the same manner as in Example 1 to produce a conductive belt.

Example 3 A conductive belt was prepared in the same manner as in Example 1, except that polysulfone (specific gravity: 1.25) was used as a binder for the protective layer and dimethylformamide was used as a solvent.

Example 4 A conductive belt was prepared in the same manner as in Example 1 except that polyetherimide (specific gravity: 1.27) was used as a binder for the protective layer and methylene chloride was used as a solvent.

The back of the conductive belts of Examples 2 to 4 was polished in the same manner as in Example 1. Table 1 shows the thicknesses of the conductive layer and the protective layer. In addition, the dispersion | variation in thickness was less than 3% in all cases. Example 1
When the protective layer was observed in the same manner as in the above, it was found that the conductive substance was mainly distributed on the surface of the protective layer. Further, the initial electric volume resistivity under the same conditions as in Example 1,
10 ^11.7 Ω · cm, 10 ^8.5 Ω · cm, 10 ^9.5 Ω · cm
, And the surface resistivity was 10 ^11.8 Ω / □ and 10
^{It was 10.8} Ω / □ and 10 ^11.5 Ω / □. After the same treatment as in Example 1, the electric volume resistivity and the surface resistivity were measured, and none of them was changed. Example 1
Similarly to the above, the image evaluation and the elongation were calculated. Table 1 shows the results.

[0047]

[Table 1]

[0048]

According to the present invention, it is possible to provide a conductive belt having sufficient conductivity and high surface smoothness and surface releasability, and a method for easily manufacturing the conductive belt. it can. Further, according to the present invention, when used as a transfer belt of an image forming apparatus, an image transfer property is improved and an image defect due to transfer failure is reduced, and the conductive belt can be easily formed. A method that can be manufactured can be provided.

[Brief description of the drawings]

FIG. 1 is an example of a schematic sectional view of a conductive belt of the present invention.

FIG. 2 is an example of a flowchart of a method for producing a conductive belt of the present invention.

FIG. 3 is an example of a schematic cross-sectional view of an image forming apparatus using the conductive belt of the present invention as a transfer belt.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Photoconductor 10 Conductive belt 11 Protective layer 11a Surface of protective layer 11b
Surface of protective layer on conductive layer side 12 Conductive layer 12a Back surface of conductive layer 13 type 24 paper

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/00 518 G03G 15/00 518 15/16 15/16 // B29K 21:00 103: 04 B29L 29 : 00 F term (reference) 2H032 AA05 BA09 BA18 BA23 BA30 2H072 CA05 JC02 3F049 BA13 LA02 LB03 4F100 AA17A AA28 AA37A AB22 AK18 AK18J AK19 AK19J 205 AK36A AK51A AK54 AL09A AR01A04G01 E02A04B01A02A04E AB16 AB18 AE03 AE09 AG03 AG16 AH33 GA01 GB01 GB26 GB28 GC04 GD02 GW50

Claims (11)

[Claims] 1. A conductive belt having a conductive layer and a protective layer formed thereon, wherein the protective layer contains a conductive substance,
A conductive belt, wherein the conductive material is inclined and dispersed such that the content of the conductive material in the protective layer increases from the conductive layer side toward the surface side. 2. The conductive belt according to claim 1, wherein the conductive layer contains an ion conductive substance, carbon black, or a conductive metal oxide. 3. The conductive belt according to claim 1, wherein the conductive layer is made of an elastomer having a urethane bond and / or a urea bond. 4. The conductive belt according to claim 3, wherein the elastomer comprises at least an amine compound, a polyol, and an isocyanate compound. 5. The conductive belt according to claim 3, wherein an average ratio of urethane bonds to urea bonds in the elastomer is from 5:95 to 95: 5. 6. The conductive belt according to claim 1, wherein the thickness is 20 to 500 μm, and the average variation of the thickness is within 3% of the thickness. 7. The conductive layer according to claim 1, wherein the conductive layer and the protective layer are formed by centrifugal molding, the protective layer on the front side is formed, and then the conductive layer is formed. The conductive belt according to the above item. 8. A protective layer forming solution containing a binder and a conductive substance is poured into a cylindrical mold, and the mold is rotated and heated to form a protective layer on the inner wall surface of the mold. A protective layer forming step, and a conductive layer forming solution containing a conductive layer forming material is charged into the mold having the protective layer formed on the inner wall surface, and the mold is rotated and heated to form the protective layer. A conductive layer forming step of forming a conductive layer on the conductive belt, wherein the specific gravity of the conductive substance is larger than the specific gravity of the binder. 9. The method for producing a conductive belt according to claim 8, wherein the solubility parameters of the protective layer forming solution and the conductive layer forming solution are different by one or more and are incompatible. 10. The conductive belt according to claim 8, wherein the conductive layer forming material reacts in the conductive layer forming step to form at least a urethane bond and a urea bond. Method of manufacturing. 11. The method for producing a conductive belt according to claim 8, further comprising a step of polishing the back surface of the conductive layer.