JP2014126602A - Transfer roll, image forming apparatus, and process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer roll which hardly causes the increase in a volume resistance value due to use and is capable of correcting the difference between the right and left of an image length.SOLUTION: A transfer roll 111 includes, for instance, a conductive support 112, a conductive elastic layer 113 provided on the conductive support 112, and a conductive resin layer 114 which is provided on the conductive elastic layer 113 and containing a resin material and a conductive agent and includes a first area 114A constituting an outermost surface and a second area 114B which is provided between the first area 114A and the conductive elastic layer 113 in a contact state with the conductive elastic layer 113 and whose surface resistivity is lower than that of the first area 114A. A nip is formed so as to obtain the inclination of a bite amount in an axial direction and when a recording medium is inserted through the nip, a difference between a conveyance amount in the part of a bite amount of 0.5 mm and a conveyance amount in the part of a bite amount of 1.3 mm is not less than 1.5 mm per 400 mm.

Description

  The present invention relates to a transfer roll, an image forming apparatus, and a process cartridge.

  In an electrophotographic apparatus such as an electrophotographic image forming apparatus, an annular body that is an annular member is often used. For example, an image holding body, a charging roll as a charging member, a developing roll as a developing device, a transfer belt And a transfer roll as a transfer device and a fixing roll as a fixing device.

For example, Patent Document 1 states that “a charging member that contacts the surface of the image carrier and charges the surface of the image carrier, and the charging member is a single-layer or multi-layer conductive tube outside the conductive elastic layer. And a charging member characterized in that it has a conductive particle layer covered with conductive particles on the outermost surface.
Patent Document 2 states that “in the charging device for applying a charge to the object to be charged by contacting the object to be charged, having a surface layer made of a fluororesin having a durometer hardness of 50 degrees or less. There has been proposed a charging device including a charging member that comes into contact with the body.

JP 2000-330359 A JP 2004-101918 A

  It is an object of the present invention to provide a transfer roll that is unlikely to cause an increase in volume resistance value due to use and that can correct a left-right difference in image length.

The above problem is solved by the following means. That is,
The invention according to claim 1
A conductive support;
A conductive elastic layer provided on the conductive support;
A conductive resin layer provided on the conductive elastic layer and including a resin material and a conductive agent, the first region constituting the outermost surface, the first region, and the conductive elasticity A conductive resin layer provided between the layers and in contact with the conductive elastic layer and having a second region having a surface resistivity lower than that of the first region;
When a nip is formed so that there is an inclination of the biting amount in the axial direction, and the recording medium is inserted through the nip, the conveyance amount at the portion where the biting amount is 0.5 mm and the portion where the biting amount is 1.3 mm A transfer roll having a difference from the conveyance amount of 1.5 mm or more / 400 mm.

The invention according to claim 2
The difference between the common logarithm of the surface resistivity of the first region (LogΩ / □) and the common logarithm of the surface resistivity of the second region (LogΩ / □) is 1 or more and 3 or less. 2. The transfer roll according to 1.

The invention according to claim 3
In the conductive resin layer, the content of the conductive agent per unit volume in the second region is larger than the content of the conductive agent per unit volume in the first region. The transfer roll described.

The invention according to claim 4
An image carrier,
Charging means for charging the image carrier;
Latent image forming means for forming a latent image on the surface of the charged image carrier;
Developing means for developing a latent image formed on the surface of the image carrier with toner to form a toner image;
4. The image forming apparatus according to claim 1, further comprising: a pressure roll that moves the transfer roll according to claim 1 and forms a nip so that there is an inclination of an amount of biting in an axial direction. Transfer means for transferring the toner image formed on the surface of the holding body to a recording medium;
An image forming apparatus comprising:

The invention according to claim 5
An image carrier, a charging unit that charges the image carrier, a latent image forming unit that forms a latent image on the surface of the charged image carrier, and a latent image formed on the surface of the image carrier is developed with toner. At least one selected from developing means for forming a toner image and fixing means for fixing the toner image transferred to the recording medium;
4. The image forming apparatus according to claim 1, further comprising: a pressure roll that moves the transfer roll according to claim 1 and forms a nip so that there is an inclination of an amount of biting in an axial direction. Transfer means for transferring the toner image formed on the surface of the holding body to a recording medium;
And a process cartridge that is detachably attached to the image forming apparatus.

According to the first aspect of the present invention, there is provided a transfer roll that is less likely to cause an increase in volume resistance value due to use and that can correct the difference in image length as compared with the case of deviating from the configuration according to the first aspect. Is done.
According to the invention according to claim 2, the difference between the common logarithm of the surface resistivity of the first region and the common logarithm of the surface resistivity of the second region is different from the case where the difference is not in the above range. There is provided a transfer roll in which increase in volume resistance is unlikely to occur.
According to the invention of claim 3, compared with the case where the content of the conductive agent per unit volume in the second region is the same or less than the content of the conductive agent per unit volume in the first region Thus, a transfer roll in which the volume resistance value is hardly increased due to is provided.

According to the fourth aspect of the present invention, there is provided an image forming apparatus in which the volume resistance value of the transfer roll due to use is unlikely to increase, and the left / right difference in image length can be corrected.
According to the fifth aspect of the present invention, there is provided a process cartridge in which the volume resistance value of the transfer roll due to use is unlikely to increase, and the left-right difference in image length can be corrected.

It is a schematic perspective view which shows the transfer roll which concerns on this embodiment. It is a schematic sectional drawing of the transfer roll concerning this embodiment. It is the schematic plan view (A) and schematic sectional drawing (B) which show an example of the circular electrode used for the measurement of surface resistivity. It is a schematic block diagram which shows an example of the coating device used in order to manufacture the electroconductive resin layer of the transfer roll which concerns on this embodiment. It is process drawing which shows an example of the manufacturing method of the conductive resin layer of the transfer roll which concerns on this embodiment. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. It is the schematic for demonstrating the measuring method of the volume resistance in an Example.

Hereinafter, an embodiment which is an example of the present invention will be described with reference to the drawings.
<Transfer roll>
FIG. 1 is a schematic perspective view showing a transfer roll according to this embodiment. FIG. 2 is a schematic cross-sectional view of the transfer roll according to this embodiment. 2 is a cross-sectional view taken along the line AA in FIG.

As shown in FIGS. 1 and 2, the transfer roll 111 according to the present embodiment is provided on, for example, a cylindrical or columnar conductive support 112 (shaft) and an outer peripheral surface of the conductive support 112. A roll member having a conductive elastic layer 113 and a conductive resin layer 114 provided on the outer peripheral surface of the conductive elastic layer 113 in contact with the conductive elastic layer 113.
The conductive resin layer 114 includes a first region 114A that constitutes the outermost surface, and a second region 114B that is in contact with the conductive elastic layer 113 and has a surface resistivity lower than that of the first region 114A.
Since the transfer roll 111 according to the present embodiment has the above-described configuration, it is difficult for the volume resistance value to increase due to use.
The reason for this is not clear, but is thought to be due to the following reasons.

Conventionally, a transfer roll provided with an unfoamed rubber layer or a resin layer as a surface layer on the surface (outer peripheral surface) of a foamed elastic roll provided with a conductive elastic layer on a conductive support (hereinafter referred to as “conventional transfer roll”) Is known). In the conventional transfer roll, charge transfer between the conductive elastic layer and the surface layer is poor, and charge accumulates at the interface between the two layers. As a result, the volume resistance value of the transfer roll may increase due to use. is there.
On the other hand, as in this embodiment, the conductive resin layer 114 has the first region 114A that is the outermost surface and the second region that is in contact with the conductive elastic layer 113 and has a lower surface resistivity than the first region. When the region 114B is included, it is considered that charge transfer is performed between the conductive elastic layer 113 and the conductive resin layer 114 without delay. Therefore, it is difficult for charges to accumulate at the interface between the conductive elastic layer 113 and the conductive resin layer 114. As a result, in the transfer roll 111 according to this embodiment, it is considered that the volume resistance value is not easily increased due to use. It is done.

  The transfer roll 111 according to the present embodiment is not limited to the above configuration, and may be a configuration having an intermediate layer provided between the conductive elastic layer 113 and the conductive support 112, for example.

  Since the transfer roll 111 according to the present embodiment is unlikely to increase in volume resistance value due to use, occurrence of image defects due to use is suppressed.

The transfer roll 111 according to the present embodiment forms a nip so that there is an inclination of the biting amount in the axial direction, and when the recording medium is inserted through the nip, the transfer roll 111 has a biting amount of 0.5 mm. The difference between the conveyance amount and the conveyance amount at the portion where the biting amount is 1.3 mm is 1.5 mm or more / 400 mm.
Here, the “biting amount” is a displacement amount in the radial direction of the transfer roll 111, and is the depth of the most recessed point in each part in the axial direction in the transfer roll 111 in a state where a nip is formed.
“There is an inclination of the biting amount in the axial direction” means that the biting amount increases from one end of the transfer roll 111 in the axial direction to the other end.
“The difference between the conveyance amount at the portion where the bite amount is 0.5 mm and the conveyance amount at the portion where the bite amount is 1.3 mm is 1.5 mm or more / 400 mm” means that the portion where the bite amount is 0.5 mm and the bite amount are 1. Of the 3 mm portions, the smaller conveyance amount means that the recording medium is conveyed 40 mm or more when the conveyance amount is larger while the recording medium is conveyed 400 mm. Either the part where the bite amount is 0.5 mm or the part where the bite amount is 1.3 mm may be larger, and the part where the bite amount is 0.5 mm is usually transported more than the part where the bite amount is 1.3 mm. Large amount.

  The transfer roll 111 according to the present embodiment can correct the difference between the left and right image lengths formed on the recording medium by adopting the above configuration. This mechanism is considered to be the following mechanism.

In an image formed on a recording medium by an electrophotographic method, a phenomenon may occur in which the length of the image differs in the conveying direction on the left and right of the conveying direction of the recording medium (referred to as “left-right difference in image length”). .
As a cause of this, for example, in a document reading apparatus, it is conceivable that a difference occurs in the moving speed of the paper between the right and left in the conveyance direction of the paper to be the original. Another possible cause is that the surface of the image carrier is worn with use, and a difference in diameter occurs between the left and right in the axial direction of the image carrier.
In the above case, the latent image formed on the image holding member and the toner image formed on the intermediate transfer member have a left-right difference in the image length.

By the way, in the transfer section of the image forming apparatus, a support roll for the intermediate transfer belt and an image holding body (hereinafter referred to as “other rolls”) and a transfer roll are arranged to face each other. The rolls are pressed against each other to form a nip (an area where the transfer roll is crushed by a load from another roll).
In this nip, if the moving speed of the recording medium (the moving amount of the recording medium) can be changed on the left and right in the transport direction, the moving speed of the recording medium in the nip is transported according to the left / right difference in the image length of the latent image or toner image. (I.e., slow down the moving speed of the recording medium on the long side of the latent image or toner image, and increase the moving speed of the recording medium on the short side of the latent image or toner image). A measure to correct the left / right difference in length can be taken.

In the transfer roll 111 according to the present embodiment, when a nip having an inclination of the biting amount is formed in the axial direction, the conveyance amount of the recording medium increases or decreases according to the biting amount. The difference in transport amount between the 5 mm region and the 1.3 mm bite portion is 1.5 mm or more / 400 mm.
If the transfer roll 111 according to the present embodiment is used, the left-right difference in image length can be corrected by the above-mentioned measures regardless of whether the transfer method is the direct transfer method or the secondary transfer method. The transfer roll with the transport amount difference of less than 1.5 mm / 400 mm cannot sufficiently correct the left-right difference in the image length depending on the above-mentioned measures.

In the transfer roll 111 according to the present embodiment, the difference in the transport amount is 1.5 mm or more / 400 mm, and from the viewpoint of more effectively correcting the left / right difference in image length, 2.0 mm or more / 400 mm is more preferable. Desirably, 3.0 mm or more / 400 mm is more desirable.
On the other hand, in the transfer roll 111 according to the present embodiment, the difference in the conveyance amount is desirably 5.0 mm or less / 400 mm, and preferably 4.5 mm or less / 400 mm, from the viewpoint that it is difficult to cause a difference in image length between the transfer portions. Is more desirable, and 4.0 mm or less / 400 mm is more desirable.

  Hereinafter, each component of the transfer roll 111 according to the present embodiment will be described in detail.

(Conductive support)
The conductive support 112 is a member that functions as an electrode of the roll member and a support member.
As the electroconductive support body 112, metal members, such as iron (free-cutting steel etc.), copper, brass, stainless steel, aluminum, nickel, are mentioned, for example.
Examples of the conductive support 112 include a member (for example, a resin or a ceramic member) whose outer surface is plated, a member in which a conductive agent is dispersed (for example, a resin or a ceramic member), and the like.
The conductive support 112 may be a hollow member (cylindrical member) or a non-hollow member.

(Conductive elastic layer)
The conductive elastic layer 113 includes, for example, a rubber material (elastic material), and may include a conductive agent and other additives. The conductive elastic layer 113 may be a conductive foamed elastic layer or a conductive non-foamed elastic layer.

Examples of the rubber material (elastic material) include a so-called elastic material having a double bond in at least a chemical structure.
Specific examples of the rubber material include, for example, isoprene rubber, chloroprene rubber, epichlorohydrin rubber, butyl rubber, polyurethane, silicone rubber, fluorine rubber, styrene-butadiene rubber, butadiene rubber, nitrile rubber, ethylene propylene rubber, epichlorohydrin-ethylene oxide copolymer rubber. , Epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, ethylene-propylene-diene terpolymer rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, and rubbers obtained by mixing these.
Among these rubber materials, polyurethane, EPDM, epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber, NBR, and rubbers obtained by mixing them are preferable.

  The conductive agent is used when the rubber material has low conductivity or when the rubber material does not have conductivity. Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent.

Examples of the electronic conductive agent include carbon black such as ketjen black and acetylene black; pyrolytic carbon, graphite; various conductive metals or alloys such as aluminum, copper, nickel, and stainless steel; tin oxide, indium oxide, and titanium oxide. And various conductive metal oxides such as tin oxide-antimony oxide solid solution, tin oxide-indium oxide solid solution; and the like.
Here, specific examples of carbon black include “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, “Special Black 4”, “Special Black 4A”, “Special Black 550”, “Special Black 6”, “Color Black FW200”, “Color Black FW2”, “Color Black FW2V”, “MONARCH1000” manufactured by Cabot, Cabot “MONARCH1300” manufactured by Cabot Corporation, “MONARCH1400” manufactured by Cabot Corporation, “MOGUL-L”, “REGAL400R”, etc.
An electronic conductive agent may be used independently and may be used in combination of 2 or more type.
The content of the electronic conductive agent may be, for example, from 1 part by mass to 30 parts by mass, and preferably from 15 parts by mass to 25 parts by mass with respect to 100 parts by mass of the rubber material.

Examples of the ionic conductive agent include quaternary ammonium salts (for example, lauryltrimethylammonium, stearyltrimethylammonium, octadodecyltrimethylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, perchlorates such as modified fatty acid and dimethylethylammonium urine, Chlorates, borofluorides, sulfates, etosulphate salts, benzyl halide salts (eg, benzyl bromide salts, benzyl chloride salts, etc.), aliphatic sulfonates, higher alcohol sulfates, higher Alcohol ethylene oxide addition sulfate ester salt, higher alcohol phosphate ester salt, higher alcohol ethylene oxide addition phosphate ester salt, various betaines, higher alcohol ethylene oxide, polyethylene glycol Fatty acid esters, polyhydric alcohol fatty acid esters.
An ionic conductive agent may be used independently and may be used in combination of 2 or more type.
The content of the ionic conductive agent is, for example, preferably in the range of 0.1 parts by weight or more and 5.0 parts by weight or less, and preferably 0.5 parts by weight or more and 3.0 parts by weight with respect to 100 parts by weight of the rubber material. It is below mass parts.

  Other additives include, for example, foaming agents, foaming aids, softeners, plasticizers, curing agents, vulcanizing agents, vulcanization accelerators, antioxidants, surfactants, coupling agents, fillers (silica , Calcium carbonate, etc.), which can be added to the elastic layer.

  The thickness of the conductive elastic layer 113 is, for example, preferably 5 mm to 20 mm, and more preferably 5 mm to 15 mm.

The conductive elastic layer 113 has a volume resistance value measured by applying an applied voltage of 1000 V under an environment of a temperature of 22 ° C. and a humidity of 55% RH, which is a common logarithmic value of 6.0 (LogΩ) or more and 8.0. It is preferably (LogΩ) or less, preferably 6.3 (LogΩ) or more and 7.8 (LogΩ) or less, more preferably 6.6 (LogΩ) or more and 7.8 (LogΩ) or less.
The volume resistance value of the conductive elastic layer 113 is adjusted by, for example, the type and amount of the conductive agent to be blended.

(Conductive resin layer)
The conductive resin layer 114 includes a resin material and a conductive agent, and may include other additives. The conductive resin layer 114 includes a first region 114A that constitutes the outermost surface, and a second region 114B that is in contact with the conductive elastic layer 113 and has a surface resistivity lower than that of the first region 114A.
For example, the conductive resin layer 114 is provided in close contact with the conductive elastic layer 113 by the tension of the layer.
In the conductive resin layer 114, the first region 114 </ b> A and the second region 114 </ b> B are provided as layered regions stacked in the radial direction of the transfer roll 111.
In the first region 114A and the second region 114B, a base material portion made of a resin material is continuous, that is, there is no interface between the first region 114A and the second region 114B. Is provided. However, the content of the conductive agent contained in each of the first region 114A and the second region 114B is different, and the content of the conductive agent per unit volume in the second region 114B is the first region 114B. It is provided in a state where the content is higher than the content of the conductive agent per unit volume in the region 114A.
The conductive resin layer 114 may have a layered intermediate region laminated in the radial direction of the transfer roll 111 between the first region 114A and the second region 114B. A configuration having only two regions of region 114A and second region 114B is desirable.

The thickness of the conductive resin layer 114 may be, for example, 50 μm or more and 150 μm or less, and desirably 70 μm or more and 100 μm or less.
The first region 114A and the second region 114B are preferably thicker in the first region 114A, and the second region 114B is formed on the surface of the conductive resin layer 114 in contact with the conductive elastic layer 113. What is necessary is just to comprise the outermost surface area | region. Here, the outermost surface region is, for example, a region from the surface where the conductive resin layer 114 is in contact with the conductive elastic layer 113 to a depth of 1 μm.

  The difference between the first region 114A and the second region 114B is the common logarithmic value (LogΩ / □) of the surface resistivity of both (the common logarithm of the surface resistivity of the first region 114A minus the second region 114B). The common logarithm of the surface resistivity is preferably from 1 to 3, more preferably from 1.1 to 2.8. Thereby, it is suppressed more excellent that the volume resistance value of the transfer roll 111 rises by use.

The surface resistivity of the first region 114A and the second region 114B is measured by the following method.
First, the conductive resin layer 114 of the transfer roll 111 is cut into a sheet, and the central portion of the sheet is cut into 4 cm × 4 cm to obtain a measurement sample.
Then, the surface resistivity is measured according to JIS K6911 using a circular electrode (for example, “UR probe” of Hiresta IP manufactured by Mitsubishi Yuka Co., Ltd.). Below, the measuring method of surface resistivity is demonstrated using figures.
FIG. 3 is a schematic plan view (A) and a schematic cross-sectional view (B) showing an example of a circular electrode. The circular electrode shown in FIG. 3 includes a first voltage application electrode A and a plate-like insulator B. The first voltage application electrode A has a cylindrical electrode portion C and a cylindrical ring electrode having an inner diameter larger than the outer diameter of the cylindrical electrode portion C and surrounding the cylindrical electrode portion C at a constant interval. Part D is provided.
Using the circular electrode and the measurement sample, the measurement sample (T in FIG. 3) is interposed between the cylindrical electrode portion C and the ring electrode portion D and the plate insulator B in the first voltage application electrode A. ) With the first region 114A facing upward, and the current flowing when the voltage V (V) is applied between the cylindrical electrode portion C and the ring electrode portion D of the first voltage application electrode A Measure I (A). Then, the surface resistivity ρs (Ω / □) is calculated by the following formula, and the surface resistivity of the first region 114A (the surface resistivity of the outermost surface of the conductive resin layer 114) is obtained. Here, in the following formula, d (mm) indicates the outer diameter of the cylindrical electrode portion C, and D (mm) indicates the inner diameter of the ring-shaped electrode portion D.
Formula: ρs = π × (D + d) / (D−d) × (V / I)
When measuring the surface resistivity of the second region 114B (surface resistivity of the surface of the conductive resin layer 114 in contact with the conductive elastic layer 113), the cylindrical electrode portion C and the ring shape of the first voltage application electrode A are measured. The measurement sample (T in FIG. 3) is sandwiched between the electrode portion D and the plate-like insulator B so that the second region 114B is on the upper side.
In addition, the surface resistivity of the conductive resin layer 114 in the present embodiment is a circular electrode (UR probe of Hiresta IP manufactured by Mitsubishi Yuka Co., Ltd .: outer diameter Φ16 mm of the cylindrical electrode portion C, the ring-shaped electrode portion D Using an inner diameter of Φ30 mm and an outer diameter of Φ40 mm, a current value after applying a voltage of 1000 V for 10 seconds in a 22 ° C./55% RH environment is calculated.

From the viewpoint of image quality, the surface resistivity of the first region 114A is a common logarithmic value of 9.0 (LogΩ / □) to 13.0 (LogΩ / □), preferably 10.0 (LogΩ / □). □) or more and 12.5 (LogΩ / □) or less, more preferably 11.0 (LogΩ / □) or more and 12.0 (LogΩ / □) or less.
From the viewpoint of image quality, the surface resistivity of the second region 114B is a common logarithmic value of 6.0 (LogΩ / □) to 11.0 (LogΩ / □), preferably 7.0 (LogΩ / □). □) to 10.5 (LogΩ / □), more preferably 8.0 (LogΩ / □) to 10.0 (LogΩ / □).
The surface resistivity of the first region 114A and the surface resistivity of the second region 114B are adjusted by the type and amount of the conductive agent blended in each region.

The conductive resin layer 114 has a volume resistance value measured by applying an applied voltage of 100 V under an environment of a temperature of 22 ° C. and a humidity of 55% RH, which is a common logarithmic value of 6.0 (LogΩ) or more and 10.0. It is preferably (LogΩ) or less, preferably 7.0 (LogΩ) or more and 9.5 (LogΩ) or less, more preferably 8.0 (LogΩ) or more and 9.0 (LogΩ) or less.
The volume resistance value of the conductive resin layer 114 is adjusted by, for example, the type and amount of the conductive agent to be blended.

Here, the volume resistance of the conductive resin layer 114 is measured according to JIS K6911 using a circular electrode (for example, UR probe of Hiresta IP manufactured by Mitsubishi Yuka Co., Ltd.). A method for measuring the volume resistance of the conductive resin layer 114 will be described with reference to the drawings. The measurement is performed using the same apparatus and the same measurement sample as those used for measuring the surface resistivity of the first region 114A and the second region 114B. However, the apparatus includes a second voltage application electrode B ′ in place of the plate-like insulator B in the surface resistivity measurement in the circular electrode shown in FIG.
Then, a measurement sample (T in FIG. 3) is sandwiched between the columnar electrode portion C and the ring-shaped electrode portion D and the second voltage application electrode B ′ in the first voltage application electrode A, and the first voltage application is performed. The current I (A) that flows when the voltage V (V) is applied between the columnar electrode portion C and the second voltage application electrode B ′ in the electrode A is measured by the equation “R = V / I”. The volume resistance value R (Ω) of the sample is calculated.
In addition, the volume resistance value of the conductive resin layer 114 in this embodiment is a round electrode (UR probe of Hiresta IP manufactured by Mitsubishi Yuka Co., Ltd .: outer diameter Φ16 mm of the columnar electrode portion C, the ring-shaped electrode portion D Using an inner diameter of Φ30 mm and an outer diameter of Φ40 mm, a current value after applying a voltage of 100 V for 10 seconds in a 22 ° C./55% RH environment is calculated.

Next, the material constituting the conductive resin layer 114 will be described.
Examples of the resin material include polycarbonate resins, polyvinylidene fluoride resins, polyalkylene phthalate resins, polycarbonate / polyalkylene phthalate mixed resins, and thermoplastic resins such as ethylene tetrafluoroethylene copolymer; polyimide, polyimide and polyamide copolymer Thermosetting resins such as coalesced (polyamideimide);
A resin material may be used independently and may be used in combination of 2 or more type.

Examples of the conductive agent include an electronic conductive agent and an ionic conductive agent. Specific examples of the electronic conductive agent and the ionic conductive agent include the specific examples described above for the conductive elastic layer.
Among them, examples of the conductive agent include conductive particles such as carbon black, graphite, aluminum, nickel, copper, tin oxide, zinc oxide, titanium oxide, and potassium titanate, and organic conductive substances such as polyaniline and polythiophene. Preferably used.

  As the conductive resin layer 114, a polyimide resin is a main component (the main component indicates that the polyimide resin content in the conductive resin layer exceeds 50% by mass), and a conductive agent such as carbon black is used as a conductive agent. The conductive resin layer in which the conductive particles are dispersed is particularly preferably used because of its excellent mechanical strength and elastic modulus.

  Examples of other additives include materials that can be added to a normal resin layer such as a plasticizer, a curing agent, a softening agent, an antioxidant, and a surfactant.

Next, a method for manufacturing the transfer roll 111 according to this embodiment will be described.
First, a roll member in which a conductive elastic layer 113 is provided on the outer peripheral surface of a cylindrical or columnar conductive support 112 (shaft) is prepared.
The method of providing the conductive resin layer 114 on the outer peripheral surface of the conductive elastic layer 113 is not particularly limited. For example, a tubular member that forms the conductive resin layer 114 is prepared, and the roll member is provided on the tubular member. Is provided, the conductive resin layer 114 is provided on the outer peripheral surface of the conductive elastic layer 113, and the transfer roll 111 according to this embodiment is obtained.

  The manufacturing method of the member which comprises the conductive resin layer 114 is not specifically limited. For example, a method of transferring a conductive agent from another material layer to one outermost surface region of a material layer made of a resin material and a conductive agent (hereinafter also referred to as “transfer method”), or a resin material and a conductive agent. And a method of concentrating the conductive agent in the material layer (hereinafter also referred to as “concentration method”).

-Transfer method-
First, a coating solution 80 containing a resin material, a conductive agent, and a solvent is prepared. In the coating solution 80, a conductive agent in an amount corresponding to the required surface resistivity of the first region 114A is dissolved or dispersed. As a dispersion method, a known method such as a jet mill, a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a colloid mill, or a paint shaker may be used.
The solvent is selected according to the resin material. The solid content concentration of the coating liquid 80 may be, for example, 10 mass% or more and 40 mass% or less, and the viscosity may be 1 Pa · s or more and 100 Pa · s or less.

Also, a cylindrical mold 91 having an outer diameter corresponding to the inner diameter of the conductive resin layer 114 (the outer diameter of the conductive elastic layer 113) is prepared. A release agent such as a silicone-based release agent is applied to the surface including at least the outer peripheral surface of the cylindrical mold 91, and a baking treatment is performed to form a release agent layer on the surface. At this time, the release agent applied to the cylindrical mold 91 is dissolved or dispersed in the type and amount of the conductive agent according to the required surface resistivity of the second region 114B. The release agent layer formed on the outer peripheral surface 91 is a release agent layer containing a conductive agent.
Here, the conductive agent used for the release agent may be the same as or different from the conductive agent used for the coating solution 80. As the conductive agent used for the release agent, a particulate or powdered conductive agent is suitable.

  FIG. 4 is a schematic configuration diagram showing an example of a coating apparatus used in the transfer method. In this coating apparatus, a nozzle 92 for discharging the coating liquid 80 onto the outer peripheral surface of the cylindrical mold 91 is disposed at a position along the outer peripheral surface of the cylindrical mold 91. The nozzle 92 is connected to the coating liquid container 93 through a pipe, and the coating liquid container 93 is connected to the pressurizing device 94 through another pipe. A blade 95 for leveling the discharged coating solution 80 on the outer peripheral surface of the cylindrical mold 91 is disposed below the nozzle 92.

  The coating liquid 80 is applied to the cylindrical mold 91 having the release agent layer by the above-described coating apparatus. Specifically, the cylindrical mold 91 is rotated in the direction of the rotation of the cylindrical mold (arrow D), the coating liquid 80 is discharged from the nozzle 92 onto the outer peripheral surface of the cylindrical mold 91, and the blade 95. Level on the outer peripheral surface of the cylindrical mold 91. The nozzle 92 and the blade 95 move at a constant speed in the nozzle and blade movement direction (arrow E), and the coating liquid 80 is applied on the outer peripheral surface of the cylindrical mold 91 with a constant thickness. The coating solution 80 is adjusted so as to be discharged from the nozzle 92 by a pressurizing device 94. Thereby, the coating film of the coating liquid 80 is formed on the outer peripheral surface of the cylindrical mold 91. The thickness of the member constituting the conductive resin layer 114 obtained is adjusted by the discharge amount of the coating liquid 80, the moving speed of the nozzle 92 and the blade 95, and the solid content concentration of the coating liquid 80.

Subsequently, the coating film of the coating solution 80 is dried by heating, and after cooling, is peeled off from the cylindrical mold 91 and is cut at a width corresponding to the width of the conductive elastic layer 113 to thereby remove the conductive resin layer 114. A constituent tubular member is obtained.
When a polyimide precursor is used as the resin material of the coating solution 80, after forming a coating film of the coating solution 80 on the outer peripheral surface of the cylindrical mold 91, the solvent is removed by drying at 80 ° C to 170 ° C. The polyimide resin film is formed by removing (drying process) and further imide conversion (baking process) by heating to 200 ° C. or higher and 350 ° C. or lower. After cooling, the polyimide resin film is peeled off from the cylindrical mold 91 and cut at a width corresponding to the width of the conductive elastic layer 113 to obtain a tubular member constituting the conductive resin layer 114.

  In the member constituting the conductive resin layer 114 obtained in this manner, the conductive agent contained in the release agent layer is contained in the outermost surface area on the side in contact with the cylindrical mold 91. Therefore, in the conductive resin layer 114, the outermost surface region on the side in contact with the cylindrical mold 91 has a higher content of the conductive agent per unit volume than the other regions, and the region where the conductive agent is unevenly distributed. Become. As a result, the second region 114B has a lower surface resistivity than the first region 114A.

-Concentration method-
This method will be described with reference to FIG.
First, a coating solution containing a resin material, a conductive agent 83, and a solvent is prepared. In the coating solution, a conductive agent in an amount corresponding to the required surface resistivity of the first region 114A is dissolved or dispersed. As the conductive agent used in the concentration method, a particulate or powdered conductive agent is suitable.
In this method, in order to apply the coating liquid to the inner peripheral surface of the cylindrical mold, a cylindrical mold 91 having an inner diameter corresponding to the outer diameter of the conductive resin layer 114 is prepared.
And a coating liquid is apply | coated to the cylindrical metal mold | die 91, and the coating film 81 of a coating liquid is formed as shown to FIG. 5 (A).
The method of applying the coating liquid onto the cylindrical mold 91 is not particularly limited. For example, there are a method in which a coating is applied to the inner peripheral surface with a blade or the like, and a method in which a part of the inner peripheral surface is applied and centrifuged to spread the entire surface. Can be mentioned. It is desirable to perform a mold release process on the surface including at least the inner peripheral surface of the cylindrical mold 91.

  Next, the coating film 81 on the cylindrical mold 91 is dried. The main drying is preferably performed so that the residual solvent amount of the coating film 81 is 25% or less, desirably 20% or less, and more desirably 15% or less. When the residual solvent amount of the coating film 81 is too large, uneven distribution (increase in density) of the conductive agent 83 described later is difficult to occur. On the other hand, the lower the amount of residual solvent, the more likely the uneven distribution (increase in density) of the conductive agent 83 described later will occur. By controlling the residual solvent amount of the coating film 81, that is, the dry state of the coating film 81, the degree of uneven distribution (concentration) of the conductive agent 83 described later is controlled, and the conductive agent 83 in the conductive resin layer 114 to be obtained is controlled. The thickness of the region where the conductor is unevenly distributed (the conductive agent unevenly distributed region 82B) is also controlled.

Here, the residual solvent amount means the ratio of the solvent weight remaining in the coating film after drying to the solvent weight present in the coating solution. The method for obtaining the residual solvent amount is as follows.
For example, if the solid content of the resin material solid content weight (resin material dry weight) and the conductive agent weight are known, the total weight of the coating film before drying is accurately weighed to obtain the total weight of the coating film. The solvent weight contained is calculated. Thereafter, the total weight of the coating film after drying is accurately weighed, and the decrease is regarded as the weight of the disappearing solvent, (coating weight before drying-coating weight after drying) / (coating weight before drying-weight of resin material solids) -Calculate the weight of the conductive agent) and determine the amount of residual solvent.

  Further, the residual solvent amount may be obtained using a heat extraction gas chromatogram mass spectrometer. An example of this measurement is shown below. For example, a sample is obtained by cutting out from 2 mg to 3 mg from the dried coating film, and the sample is weighed and then placed in a heat extraction device (PY2020D manufactured by Frontier Laboratories) and heated to 400 ° C. Volatile components are injected into a gas chromatogram mass spectrometer (GCMS-QP2010, manufactured by Shimadzu Corporation) through an interface at 320 ° C. and quantified. That is, using helium gas as a carrier gas, 1/51 of the amount volatilized from the sample (split ratio 50: 1) is a linear velocity of 153.8 cm / second (carrier gas flow rate at a column temperature of 50 ° C., 1.50 ml / min, pressure) 50 kPa) and injected into a column (frontier lab capillary column UA-5) having an inner diameter of Φ0.25 μm × 30 m. Next, after holding at 50 ° C. for 3 minutes, the column is heated to 400 ° C. at a rate of 8 ° C. per minute and held at the same temperature for 10 minutes to desorb volatile components. Further, a volatile component is injected into the mass spectrometer at an interface temperature of 320 ° C., and a peak area corresponding to the solvent is obtained. The quantification is performed by preparing a calibration curve in advance with a known amount of the same solvent. The solvent weight determined in this way is divided by the sample weight after drying to determine the residual solvent amount. However, the above measurement example is an example, and the measurement conditions may be changed depending on the decomposition or changing temperature of the resin used or the boiling point of the solvent.

Next, as shown in FIG. 5B, an elution solvent 84 for eluting the resin material is applied to the surface of the dried coating film 81. In the region where the elution solvent 84 is applied, the elution solvent 84 penetrates into the dried coating film 81, and the region under the application surface of the elution solvent 84 is in a swollen state. Then, the resin material in the region below the application surface is eluted to the elution solvent 84 side, but the conductive agent 83 is difficult to elute or move to the elution solvent 84.
Then, as shown in FIG. 5C, the density of the conductive agent 83 is increased in the area below the coating surface from which the resin material is eluted, as much as the resin material is eluted in the area below the other areas. As a result, a region where the conductive agent 83 is unevenly distributed is formed. In addition, 81B of FIG.5 (C) shows the area | region where the electrically conductive agent 83 in the coating film 81 was unevenly distributed.

The elution solvent 84 for eluting the resin material is selected from solvents that dissolve the resin material. Here, dissolving the resin material means that the resin solid content is dissolved by 10% by mass or more with respect to the solvent at 25 ° C.
As the elution solvent, the same type of solvent as the solvent contained in the coating solution is preferable. For example, when a polyimide precursor solution is used as a coating solution, a polar solvent is exemplified, and for example, N, N-dialkylamides are desirable, and specifically, for example, N, N-dimethylformamide, N, N-dimethyl is used. Acetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine, tetramethylene sulfone, dimethyltetramethylene And sulfone. These may be used alone or in combination of two or more.

The application amount of the elution solvent 84 is, for example, 0.001 g / cm ² or more and 1 g / cm ² or less, desirably 0.01 g / cm ² or more and 1 g / cm ² or less, and more desirably 0.01 g / cm 2. ² or more and 0.5 g / cm ² or less.
As a method for applying the elution solvent 84, there are a method of applying to the inner peripheral surface with a blade or the like, and a method of applying to a part of the inner peripheral surface and centrifuging to spread the entire surface.

Next, the elution solvent 84 applied to the surface of the coating film 81 is removed by drying, and the resin film 82 appears on the cylindrical mold 91 as shown in FIG.
At this time, since the elution solvent 84 from which the resin material is eluted contains the resin material, by drying the elution solvent 84, the resin material is precipitated and the conductive agent 83 is unevenly distributed. A region made of a resin material is formed on the top.
Since the elution solvent 84 does not contain the conductive agent 83 or is smaller than other regions, the conductive agent 83 does not contain the conductive agent 83 on the region where the conductive agent 83 is unevenly distributed. Region 82C is formed. A conductive agent unevenly distributed region 82B in which the conductive agent 83 is unevenly distributed is formed in a region below the conductive agent non-containing region 82C, and a conductive agent density is lower in the region below the conductive agent unevenly distributed region 82B than the conductive agent unevenly distributed region 82B. A conductive agent containing region 82A including the conductive agent 83 is formed. Note that the conductive agent non-containing region 82C may include a small amount of the conductive agent 83.
In the case where a polyimide precursor solution is used as the resin material, after the elution solvent 84 is dried, the polyimide resin film is formed by heating to 200 ° C. or more and 350 ° C. or less for imide conversion (firing process).

Next, the inner peripheral surface of the resin film 82 is polished to remove the conductive agent-free region 82C, and as shown in FIG. 5E, two regions having different conductive agent densities (the conductive agent unevenly distributed region 82B and the conductive region) Into a resin film made of the agent-containing region 82A).
Then, the processed resin film is peeled off from the cylindrical mold 91 and cut with a width corresponding to the width of the conductive elastic layer 113 to obtain a tubular member constituting the conductive resin layer 114.

  Roll member in which the conductive elastic layer 113 is provided on the outer peripheral surface of the cylindrical or columnar conductive support 112 on the tubular member constituting the conductive resin layer 114 manufactured by the above transfer method or concentration method Is inserted, the conductive resin layer 114 is provided on the outer peripheral surface of the conductive elastic layer 113, and the transfer roll 111 according to this embodiment is obtained.

<Image forming apparatus, process cartridge>
The image forming apparatus according to the present embodiment is an image forming apparatus including a transfer roll, and the transfer roll according to the present embodiment is applied as the transfer roll.
Specifically, for example, the image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges the image carrier, and a latent image forming unit that forms a latent image on the surface of the charged image carrier. A developing unit that develops a latent image formed on the surface of the image carrier with toner to form a toner image; and a transfer unit that transfers the toner image formed on the surface of the image carrier to a recording medium. The transfer unit includes the transfer roll according to the present embodiment.

  The transfer means is formed on the surface of the image transfer body and the intermediate transfer body onto which the toner image formed on the surface of the image carrier is transferred, for example, or the structure of the direct transfer method to the recording medium provided with the transfer roll alone In the configuration of an intermediate transfer system, a primary transfer roll that transfers the toner image transferred onto the surface of the intermediate transfer member and a secondary transfer roll that transfers the toner image transferred onto the surface of the intermediate transfer member onto a recording medium. As a transfer roll according to the present embodiment.

The transfer unit is preferably a transfer unit capable of forming a nip having an inclination of the biting amount in a direction orthogonal to the conveyance direction.
Specifically, the transfer unit is preferably a transfer unit including a transfer roll and a pressure mechanism that moves the transfer roll to form a nip so that an inclination of the biting amount exists in the axial direction. This pressurizing mechanism is configured by setting the distance between the transfer roller and the opposing member (intermediate transfer body support roll or image holding body) that faces the transfer roll and forms a nip on the transfer roll at both ends in the axial direction. A nip having an inclination of the biting amount in the axial direction of the transfer roll is formed.

  As the image forming apparatus according to the present embodiment, for example, a normal monocolor image forming apparatus in which only a single color toner is accommodated in a developing device, a toner image held on an image holding member is directly transferred to a recording medium. An image forming apparatus, a color image forming apparatus that repeats primary transfer of a toner image held on an image holding body to an intermediate transfer body sequentially, and a plurality of image holding bodies each having a developing device for each color are arranged in series on the intermediate transfer body. Any of the arranged tandem color image forming apparatuses may be used.

  The process cartridge according to the present embodiment is attached to and detached from the image forming apparatus having the above-described configuration, for example, and includes at least a transfer roll according to the present embodiment. The process cartridge according to the present embodiment is formed on the surface of an image carrier, a charging unit that charges the image carrier, a latent image forming unit that forms a latent image on the surface of the charged image carrier, and a surface of the image carrier. At least one selected from developing means for developing a latent image with toner to form a toner image, and transfer means for transferring the toner image formed on the surface of the image carrier to a recording medium, The means includes the transfer roll according to the present embodiment.

  Hereinafter, an image forming apparatus according to the present embodiment will be described with reference to the drawings. FIG. 6 is a schematic configuration diagram illustrating the image forming apparatus according to the embodiment.

  The image forming apparatus shown in FIG. 6 is a first to first electrophotographic method that outputs yellow (Y), magenta (M), cyan (C), and black (K) images based on color-separated image data. Fourth image forming units 10Y, 10M, 10C, and 10K (image forming means) are provided. These image forming units (hereinafter simply referred to as “units”) 10Y, 10M, 10C, and 10K are juxtaposed at a specific distance in the horizontal direction. The units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the main body of the image forming apparatus.

Above each of the units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 as an intermediate transfer member is extended through each unit. The intermediate transfer belt 20 is wound around a drive roll 22 and a support roll 24 that are in contact with the inner surface of the intermediate transfer belt 20 that are spaced apart from each other in the left to right direction in FIG. The transfer unit for the image forming apparatus is configured to run in the direction from 10Y to the fourth unit 10K.
The support roll 24 is biased in a direction away from the drive roll 22 by a spring or the like (not shown), and a specific tension is applied to the intermediate transfer belt 20 wound around the support roll 24. An intermediate transfer member cleaning device 30 is provided on the side of the image carrier of the intermediate transfer belt 20 so as to face the drive roll 22.
Further, each of the developing devices (developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K includes yellow, magenta, cyan, and black contained in the toner cartridges 8Y, 8M, 8C, and 8K. The four color toners can be supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K described above have the same configuration, here, the first unit that forms a yellow image disposed on the upstream side in the intermediate transfer belt traveling direction. 10Y will be described as a representative. Note that the second to fourth units are denoted by reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y) in the same parts as the first unit 10Y. Description of 10M, 10C, 10K is omitted.

The first unit 10Y has a photoreceptor 1Y that functions as an image holding member. Around the photoreceptor 1Y, a charging roll 2Y for charging the surface of the photoreceptor 1Y to a specific potential, and the charged surface is exposed by a laser beam 3Y based on the color-separated image signal to form an electrostatic charge image. An exposure device 3; a developing device (developing unit) 4Y for supplying the charged toner to the electrostatic image and developing the electrostatic image; a primary transfer roll 5Y (primary transfer unit) for transferring the developed toner image onto the intermediate transfer belt 20; ), And a photoreceptor cleaning device (cleaning means) 6Y for removing toner remaining on the surface of the photoreceptor 1Y after the primary transfer with a cleaning blade.
The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20, and is provided at a position facing the photoreceptor 1Y. Further, a bias power source (not shown) for applying a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

Hereinafter, an operation of forming a yellow image in the first unit 10Y will be described. First, prior to the operation, the surface of the photoreceptor 1Y is charged to a potential of, for example, −600V or more and −800V or less by the charging roll 2Y.
The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate (volume resistivity at 20 ° C .: 1 × 10 ⁶ Ωcm or less). This photosensitive layer usually has a high resistance (a resistance close to that of a general resin), but has a property that the specific resistance of the portion irradiated with the laser beam changes when irradiated with the laser beam 3Y. . Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 in accordance with yellow image data sent from a control unit (not shown). The laser beam 3Y is applied to the photosensitive layer on the surface of the photoreceptor 1Y, whereby an electrostatic charge image of a yellow print pattern is formed on the surface of the photoreceptor 1Y.

The electrostatic charge image is an image formed on the surface of the photoreceptor 1Y by charging, and the specific resistance of the irradiated portion of the photosensitive layer is lowered by the laser beam 3Y, and the charged charge on the surface of the photoreceptor 1Y flows. On the other hand, this is a so-called negative latent image formed by the charge remaining in the portion not irradiated with the laser beam 3Y.
The electrostatic image formed on the photoreceptor 1Y in this way is rotated to a specific development position as the photoreceptor 1Y travels. At this development position, the electrostatic charge image on the photoreceptor 1Y is visualized (developed image) by the developing device 4Y.

  For example, yellow toner is accommodated in the developing device 4Y. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y, and has a charge of the same polarity (negative polarity) as the charged charge on the photoreceptor 1Y, and a developer roll (developer holder). Is held on. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner is electrostatically attached to the latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. . The photoreceptor 1Y on which the yellow toner image is formed continues to run at a specific speed, and the toner image developed on the photoreceptor 1Y is conveyed to a specific primary transfer position.

When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer, a specific primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y is applied to the toner image. The toner image on the photoreceptor 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a (+) polarity opposite to the polarity (−) of the toner, and is controlled to +10 μA, for example, by the control unit (not shown) in the first unit 10Y.
On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the cleaning device 6Y.

Further, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K after the second unit 10M is also controlled according to the first unit.
Thus, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of the respective colors are superimposed and transferred in a multiple manner.

  The intermediate transfer belt 20 onto which the four color toner images have been transferred through the first to fourth units is disposed on the image transfer surface side of the intermediate transfer belt 20, the support roll 24 that contacts the inner surface of the intermediate transfer belt 20. The secondary transfer roll (secondary transfer means) 26 thus formed reaches a secondary transfer portion.

The secondary transfer roll 26 is supported by a pressure mechanism (not shown) via bearings or the like at both ends of the shaft, and presses against the support roll 24 via the intermediate transfer belt 20.
The pressurizing mechanism moves the secondary transfer roll 26 in the direction toward or away from the axis of the support roll 24 by manual or drive power, and the interaxial distance between the secondary transfer roll 26 and the support roll 24. To change. The pressure mechanism is configured so that the moving distance of the secondary transfer roll 26 can be adjusted separately at both ends of the shaft, and the distance between the axes of the secondary transfer roll 26 and the support roll 24 is a target value at each end of the shaft. Can be set to Further, the pressurizing mechanism is a detecting means (not shown) for detecting the left-right difference in the image length formed on the recording medium or a detecting means (not-notified) for detecting the left-right difference in the length of the toner image on the intermediate transfer belt 20. The left and right difference information is transmitted from (shown), and the movement distance of the secondary transfer roll 26 is adjusted to both ends of the shaft in accordance with the information.
As a result, the amount of biting of the secondary transfer roll 26 in the nip is adjusted in the axial direction, and a left-right difference occurs in the conveyance amount (movement speed of the recording medium in the nip), thereby correcting the left-right difference in image length.

  The recording medium P is fed at a specific timing into a gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are in pressure contact via a supply mechanism, and a specific secondary transfer bias is applied to the support roll 24. . The transfer bias applied at this time is a (−) polarity that is the same polarity as the polarity (−) of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording medium P is applied to the toner image, so The toner image is transferred onto the recording medium P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detecting means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

Thereafter, the recording medium P is sent to a fixing device (fixing means) 28, the toner image is heated, and the color-superposed toner image is melted and fixed on the recording medium P. The recording medium P on which the color image has been fixed is unloaded to the discharge unit, and a series of color image forming operations is completed.
The image forming apparatus exemplified above is configured to transfer the toner image to the recording medium P via the intermediate transfer belt 20, but is not limited to this configuration, and the toner image is directly transferred from the photoconductor. It may be a structure that is transferred to the recording medium P.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.
In the following, “part” is based on mass unless otherwise specified.

<Preparation of roll member with conductive elastic layer>
(Preparation of roll with elastic layer-A)
By containing an ethylene oxide group, 60 parts of epichlorohydrin rubber (Epichromer CG-102 manufactured by Daiso Corp.) and 30 parts of acrylonitrile-butadiene rubber (Nipol DN-219 manufactured by Nippon Zeon Co., Ltd.) excellent in ion conductivity are mixed, and sulfur is mixed. Add 1 part (200 mesh manufactured by Tsurumi Chemical Co., Ltd.), 1.5 parts vulcanization accelerator (Noxeller M manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) and 6 parts azodicarbonamide as a foaming agent, and open roll Kneaded to obtain a mixture. Next, this mixture was wound around a SUS roll (conductive support) having a diameter of 12 mm. Subsequently, a SUS roll was heated to 160 ° C. as a heat source, and the wound mixture was vulcanized and foamed for 2 hours to form a conductive elastic layer on the conductive support. The outer peripheral surface of this conductive elastic layer was polished and processed into an outer diameter of 28 mm (the thickness of the conductive elastic layer was 8 mm) to obtain Roll-A with an elastic layer.
The Asker C hardness measured under a 1000 g load condition was 12 degrees by pressing a measuring needle of an Asker C-type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) on the surface of the conductive elastic layer of Roll-A with an elastic layer.

(Preparation of roll with elastic layer-B)
A roll-B with an elastic layer was produced in the same manner as the production of roll-A with an elastic layer except that the blowing agent was replaced with 6 parts of dinitropentamethylenetetramine.
The Asker C hardness measured under the condition of 1000 g load was 8 degrees by pressing a measuring needle of an Asker C-type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) on the surface of the conductive elastic layer of Roll-B with an elastic layer.

(Production of roll with elastic layer-C)
A roll-C with an elastic layer was prepared in the same manner as the roll-A with an elastic layer except that 28 parts of carbon black (Degussa Special Black 250) was also mixed with the mixture for the conductive elastic layer.
The Asker C hardness measured under the condition of a load of 1000 g by pressing a measuring needle of an Asker C-type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) on the surface of the conductive elastic layer of the roll-C with an elastic layer was 28 degrees.

(Preparation of roll with elastic layer-D)
Except that 28 parts of carbon black (Degussa Special Black 250) was mixed with the mixture for the conductive elastic layer, and the foaming agent was replaced with 6 parts of dinitropentamethylenetetramine, the same as the production of Roll-A with Elastic Layer. Thus, roll-D with an elastic layer was produced.
The Asker C hardness measured under the condition of a load of 1000 g by pressing a measuring needle of an Asker C-type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) on the surface of the conductive elastic layer of Roll-D with elastic layer was 25 degrees.

(Preparation of roll with elastic layer-E)
A urethane prepolymer was obtained by reacting 100 parts of polyoxypropylene triol having a molecular weight of 3000 with 25 parts of tolylene diisocyanate (TDI-80 manufactured by Nippon Polyurethane Co., Ltd.). 100 parts of this urethane prepolymer, 20 parts of carbon black (Special Black 4A manufactured by Degussa), 1 part of N-methylmorpholine and 0.3 part of triethylamine as a reaction activation catalyst, and a silicon surfactant (Nihon Unicar) 3 parts of L-520) were added, mixed with stirring for 30 seconds and foamed to obtain a foaming liquid. Next, this foamed liquid is poured into a mold containing a SUS roll (conductive support) having a diameter of 12 mm and thermally cured at 80 ° C., and a foamed urethane foam layer (conductive) is formed around the conductive support. Elastic layer) was formed. The outer peripheral surface of this conductive elastic layer was polished and processed into an outer diameter of 28 mm (the thickness of the conductive elastic layer was 8 mm) to obtain Roll-E with an elastic layer.
The Asker C hardness measured under the condition of a load of 1000 g by pressing a measuring needle of an Asker C-type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) on the surface of the conductive elastic layer of the roll-E with elastic layer was 22 degrees.

(Production of Roll-F with Elastic Layer)
Except that the blowing agent was replaced with 6 parts of benzenesulfonyl hydrazide, Roll-F with Elastic Layer was prepared in the same manner as in Preparation of Roll-A with Elastic Layer.
The Asker C hardness measured under the condition of a load of 1000 g by pressing a measuring needle of an Asker C-type hardness meter (manufactured by Kobunshi Keiki Co., Ltd.) on the surface of the conductive elastic layer of Roll-F with an elastic layer was 40 degrees.

<Preparation of member for conductive resin layer>
(Preparation of coated tube-A)
N-methyl-2-pyrrolidone (NMP) solution of polyamic acid composed of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether (the solid content ratio after imide conversion is 18% by mass), carbon black (Degussa Special Black 4) is added so that the solid content of polyamic acid is 100 parts of carbon black (Degussa Special Black 4), and a jet mill disperser (Genus P. Using a minimum cross-sectional area of 0.032 mm ² ), the dispersion unit was passed through the dispersion unit 5 times at a pressure of 200 MPa, dispersed and mixed to obtain a dispersion.
To this dispersion, an NMP solution of the polyamic acid (solid content ratio after imide conversion is 18% by mass) is added so as to be 27 parts of carbon black with respect to 100 parts of the solid content of polyamic acid, and a planetary mixer ( A carbon black-dispersed polyimide precursor solution was prepared by stirring and mixing using an Aiko mixer manufactured by Aikosha Seisakusho.

  An aluminum cylindrical tube having an outer diameter of 28 mm, a length of 500 mm, and a thickness of 6 mm was prepared. This aluminum cylindrical tube is roughened to a surface roughness Ra of 0.35 μm by blasting with spherical glass particles. On the surface of this cylindrical tube, a solution obtained by stirring and mixing 1 g of a conductive agent (tin oxide, Mitsui Metals Pastorran 6010) to 100 g of a silicone release agent (KS700 manufactured by Shin-Etsu Chemical Co., Ltd.) is applied at 300 ° C. Time-baking treatment was performed. In this way, an aluminum cylindrical tube having a release agent layer containing a conductive agent formed on the surface was produced.

The aluminum cylindrical tube obtained above was rotated at 50 rpm with the axial direction horizontal, and the carbon black-dispersed polyimide precursor solution was applied to the outer surface of the cylindrical tube through a dispenser so as to have a thickness of 0.625 mm.
The cylindrical tube coated with the carbon black-dispersed polyimide precursor solution is heated and dried at 60 ° C. for 25 minutes and 120 ° C. for 40 minutes while rotating at 6 rpm while being horizontally horizontal, and the carbon black-dispersed polyimide precursor is dried. A film was formed. Subsequently, the dried film was heated at 200 ° C. for 30 minutes, 260 ° C. for 30 minutes, 300 ° C. for 30 minutes, and 320 ° C. for 20 minutes to form a carbon black-dispersed polyimide film, which was removed from the aluminum cylindrical tube. . Subsequently, it cut | disconnected by the width | variety according to the width | variety of the electroconductive elastic layer of roll-A with an elastic layer.
The tubular carbon black-dispersed polyimide film thus obtained was designated as coated tube-A.

(Preparation of coated tube-B)
The liquid applied to the surface of the aluminum cylindrical tube was replaced with 100 g of a silicone release agent (KS700 manufactured by Shin-Etsu Chemical Co., Ltd.) and 3 g of a conductive agent (tin oxide, Mitsui Kinzoku Pastorran 6010) stirred and mixed immediately before application. Except for the above, a tubular carbon black-dispersed polyimide film was produced in the same manner as in the production of the coated tube-A. This carbon black-dispersed polyimide film was designated as coated tube-B.

(Preparation of coated tube-C)
The liquid applied to the surface of the aluminum cylindrical tube is mixed with 100 g of a silicone release agent (KS700 manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.5 g of a conductive agent (tin oxide, Mitsui Metals Pastorran 6010) with stirring and mixing immediately before application. A tubular carbon black-dispersed polyimide film was produced in the same manner as in the production of the coated tube-A, except that it was replaced. This carbon black-dispersed polyimide film was designated as coated tube-C.

(Preparation of coated tube-D)
The liquid applied to the surface of the aluminum cylindrical tube was replaced with 100 g of a silicone-based mold release agent (KS700 manufactured by Shin-Etsu Chemical Co., Ltd.) and 4 g of a conductive agent (tin oxide, Mitsui Kinzoku Pastorran 6010) stirred and mixed immediately before application. Except for the above, a tubular carbon black-dispersed polyimide film was produced in the same manner as in the production of the coated tube-A. This carbon black-dispersed polyimide film was designated as coated tube-D.

(Preparation of coated tube-E)
Tubular carbon black-dispersed polyimide coating, similar to the preparation of coated tube-A, except that the liquid applied to the surface of the aluminum cylindrical tube was replaced with a silicone mold release agent (KS700 manufactured by Shin-Etsu Chemical Co., Ltd.). Was made. This carbon black-dispersed polyimide film was designated as coated tube-E.

<Example 1>
(Preparation of transfer roll-1)
The roll with elastic layer-A was inserted while feeding air into the coated tube-A. Thus, a transfer roll-1 was obtained in which the conductive resin layer composed of the coated tube-A was provided on the conductive elastic layer.

<Examples 2 to 8>
(Preparation of transfer rolls 2 to 8)
Transfer rolls 2 to 8 were obtained in the same manner as in the preparation of transfer roll-1, with the combination of the roll with the elastic layer and the coated tube shown in Table 1.

<Comparative Example 1>
(Preparation of transfer roll-C1)
The roll with elastic layer-A was used as the transfer roll-C1 as it was.

<Comparative example 2>
(Preparation of transfer roll-C2)
The roll with elastic layer-F was used as it is as the transfer roll-C2.

<Comparative Examples 3-8>
(Preparation of transfer rolls C3 to C8)
Transfer rolls-C3 to C8 were obtained in the same manner as in the preparation of transfer roll-1, with the combination of the roll with elastic layer and the coated tube shown in Table 1.

<Comparative Example 9>
(Preparation of transfer roll-C9)
A urethane resin diluent comprising 100 parts of an N, N-dimethylformamide solution of polyether urethane resin (solid content 30% by mass, KK124 manufactured by Dainichi Seika), 250 parts of N, N-dimethylformamide, and 50 parts of methyl ethyl ketone In addition, 12 parts of carbon black (Mitsubishi Chemical # 3030B) was added and dispersed with a bead mill to obtain a coating solution. This coating solution was applied to the outer surface of the roll-F with an elastic layer by a spray method, then inserted into the coated tube-E, treated at 160 ° C. for 90 minutes, and the coating solution was dried to form an adhesive layer. Thus, Transfer Roll-C9 was obtained in which an adhesive layer was provided between the conductive elastic layer and the conductive resin layer composed of the coated tube-E.
In the transfer roll-C9, the cured product of the coating solution entered the foamed cells of the conductive elastic layer, resulting in uneven hardness.

<Comparative Example 10>
(Preparation of transfer roll-C10)
A transfer roll-C10 was produced in the same manner as in Comparative Example 9, except that the roll-F with elastic layer was replaced with the roll-A with elastic layer and the coated tube-E was replaced with the coated tube-A.
In the transfer roll-C10, the cured product of the coating solution entered the foamed cells of the conductive elastic layer, resulting in uneven hardness.

<Measurement of physical properties>
(Surface resistivity of the first region and the second region in the conductive resin layer)
The conductive resin layers of the transfer rolls of Examples 1 to 8 and Comparative Examples 3 to 8 were cut into sheets, and the central part of the sheets was cut out to 4 cm × 4 cm to obtain measurement samples.
Using this measurement sample, the surface resistivity of the surface that was the outermost surface of the conductive resin layer and the surface that was in contact with the conductive elastic layer were measured using the surface resistivity measurement method described above. It was measured. The surface resistivity of the surface that is the outermost surface of the conductive resin layer is the surface resistivity of the first region, and the surface resistivity of the surface that is in contact with the conductive elastic layer is the second surface resistivity. The surface resistivity of the region. The measurement results are shown in Table 1 below as common logarithm values (LogΩ / □).

(Difference between right and left of the transport amount of the recording medium when the biting amount is inclined in the axial direction of the transfer roll)
The transfer roll (diameter 28 mm, length of conductive elastic layer and conductive resin layer 350 mm) of each example and each comparative example is mounted as a secondary transfer roll on an image forming apparatus manufactured by Fuji Xerox Co., Ltd., DocuCenterColor 2220 remodeling machine. did. As the intermediate transfer belt, an intermediate transfer belt mounted on DocuCenterColor 2220 manufactured by Fuji Xerox Co., Ltd. was used.
The image forming apparatus was set so that the speed of the secondary transfer roll was 500 mm / sec.
As a recording medium, Fuji Xerox C2 paper (basis weight 70 g / m ² , thickness 89 μm) was prepared.

In the image forming apparatus, the amount of biting of the secondary transfer roll is 0.9 mm over the entire axial direction, and when the image is formed based on the image data from the computer, the difference in the image length formed on the recording medium is different. It was confirmed that no occurred.
In this image forming apparatus, a pressurizing device that moves the secondary transfer roll is driven, and the axis between the secondary transfer roll and the support roll (the roll member facing the secondary transfer roll via the intermediate transfer belt) The distance was adjusted, the amount of biting of the secondary transfer roll was inclined in the axial direction, and a nip having the amount of biting below was formed.

-At the center of the secondary transfer roll in the axial direction, the amount of biting is 0.9 mm.
-The biting amount is 0.5 mm at a position of 145 mm from the center in the axial direction of the secondary transfer roll to one side in the axial direction.
The biting amount is 1.3 mm at a position of 145 mm from the center in the axial direction of the secondary transfer roll to the other in the axial direction.

Using the image forming apparatus having the nip formed as described above, A3 paper is used, the long side direction is the transport direction, and 1 mm perpendicular to the long side and short side of the A3 paper is based on image data from the computer. A 1 mm grid pattern was imaged.
Then, in the lattice pattern drawn on A3 paper, the length of 400 lattice units was measured for the following three straight lines.

A straight line parallel to the long side of the A3 paper and closest to the center of the short side (that is, a straight line corresponding to a portion where the bite amount of the secondary transfer roll is 0.9 mm). Hereinafter referred to as “central straight line”.
A straight line parallel to the long side of the A3 paper and located closest to the position of 145 mm from the center of the short side to one side (that is, a straight line corresponding to a portion where the bite amount of the secondary transfer roll is 0.5 mm) . Hereinafter, it is referred to as a “left straight line”.
A straight line parallel to the long side of the A3 paper and located closest to the position of 145 mm from the center of the short side to the other side (that is, a straight line corresponding to a portion where the bite amount of the secondary transfer roll is 1.3 mm) . Hereinafter referred to as “right straight line”.

Then, the difference between the length of the left straight line and the right straight line (| the length of the left straight line−the length of the right straight line | [mm]) is calculated, and the shorter of the left straight line and the right straight line. Left / right difference per straight line of 400 mm (| left straight line length−right straight line length | ÷ shorter straight line length × 400 [mm]). The results are shown in Table 1 below.
Here, the difference in length between the left straight line and the right straight line indicates that there is a difference in the transport amount between the transfer roll biting part of 0.5 mm and the biting part of 1.3 mm. The difference in image length corresponds to the difference in transport amount.

<Evaluation>
The transfer roll of each Example and each Comparative Example was mounted as a secondary transfer roll on an image forming apparatus manufactured by Fuji Xerox Co., Ltd., DocuCentreColor 2220 remodeling machine (process speed 500 mm / sec, secondary transfer current 100 μA). Using this image forming apparatus, C2 paper (A4 paper) manufactured by Fuji Xerox Co., Ltd. is used, and 50,000 continuous images with letters and patches are continuously imaged in an environment of temperature 10 ° C. and humidity 15% RH. The following evaluation was performed. The results are shown in Table 1 below. In Table 1, “Before” means before 50,000 images are formed, and “After” means after 50,000 images are formed.

(Measurement of volume resistance)
The volume resistance (R) (Ω) of the transfer roll was measured before and after the above-mentioned image formation on 50,000 sheets. The measurement method will be described with reference to FIG.
As shown in FIG. 7, the transfer roll 60 is placed on the metal plate 70 and a load of 500 g is applied to the locations indicated by arrows A1 and A2 on both ends of the cored bar 50, and the temperature is 22 ° C. and the humidity is 55% RH. Below, an applied voltage of 1000 V is applied between the core metal 50 and the metal plate 70, the current value I (A) after 10 seconds is read, and the volume resistance (R) is calculated by the equation “R = V / I”. did. This measurement and calculation were performed for four points by rotating the transfer roll 60 in the circumferential direction by 90 °, and the average value was defined as the volume resistance (R) of the transfer roll. Table 1 shows a common logarithmic value (LogΩ) of the volume resistance.

(image quality)
Before and after the above 50,000 image formation, a halftone image (image density 20%, 30%, 40%) was formed on the entire surface of the paper, visually observed, and the image quality was evaluated according to the following criteria. .
A: A halftone without density unevenness was obtained.
B: A slight difference in density was observed, but it was an acceptable level.
C: Density unevenness in halftone.
D: There were white spots.

  From the results shown in Table 1, it can be seen that this example is less likely to cause an increase in volume resistance value due to use than the comparative example, and can correct the left-right difference in the image.

1Y, 1M, 1C, 1K photoreceptor 2Y, 2M, 2C, 2K charging roll 3Y, 3M, 3C, 3K laser beam 3 exposure device 4Y, 4M, 4C, 4K developing device 5Y, 5M, 5C, 5K primary transfer roll 6Y , 6M, 6C, 6K Cleaning devices 8Y, 8M, 8C, 8K Toner cartridges 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt 22 Drive roll 24 Support roll 26 Secondary transfer roll 28 Fixing device 30 Intermediate transfer member cleaning apparatus

50 Metal core 60 Transfer roll 70 Metal plate

80 coating liquid 81 coating film 82 resin film 82A conductive agent containing region 82B conductive agent unevenly distributed region 83C conductive agent non-containing region 83 conductive agent 84 elution solvent 91 cylindrical mold 92 nozzle 93 coating solution container 94 pressurizing device 95 blade

111 Transfer Roll 112 Conductive Support 113 Conductive Elastic Layer 114 Conductive Resin Layer 114A First Region 114B Second Region

Claims (5)

A conductive support;
A conductive elastic layer provided on the conductive support;
A conductive resin layer provided on the conductive elastic layer and including a resin material and a conductive agent, the first region constituting the outermost surface, the first region, and the conductive elasticity A conductive resin layer provided between the layers and in contact with the conductive elastic layer and having a second region having a surface resistivity lower than that of the first region;
When a nip is formed so that there is an inclination of the biting amount in the axial direction, and the recording medium is inserted through the nip, the conveyance amount at the portion where the biting amount is 0.5 mm and the portion where the biting amount is 1.3 mm A transfer roll having a difference from the conveyance amount of 1.5 mm or more / 400 mm.   The difference between the common logarithm of the surface resistivity of the first region (LogΩ / □) and the common logarithm of the surface resistivity of the second region (LogΩ / □) is 1 or more and 3 or less. 2. The transfer roll according to 1.   In the conductive resin layer, the content of the conductive agent per unit volume in the second region is larger than the content of the conductive agent per unit volume in the first region. The transfer roll described. An image carrier,
Charging means for charging the image carrier;
Latent image forming means for forming a latent image on the surface of the charged image carrier;
Developing means for developing a latent image formed on the surface of the image carrier with toner to form a toner image;
4. The image forming apparatus according to claim 1, further comprising: a pressure roll that moves the transfer roll according to claim 1 and forms a nip so that there is an inclination of an amount of biting in an axial direction. Transfer means for transferring the toner image formed on the surface of the holding body to a recording medium;
An image forming apparatus comprising: An image carrier, a charging unit that charges the image carrier, a latent image forming unit that forms a latent image on the surface of the charged image carrier, and a latent image formed on the surface of the image carrier is developed with toner. At least one selected from developing means for forming a toner image and fixing means for fixing the toner image transferred to the recording medium;
4. The image forming apparatus according to claim 1, further comprising: a pressure roll that moves the transfer roll according to claim 1 and forms a nip so that there is an inclination of an amount of biting in an axial direction. Transfer means for transferring the toner image formed on the surface of the holding body to a recording medium;
And a process cartridge that is detachably attached to the image forming apparatus.