JP2016118647A - Transfer member, image forming apparatus, process cartridge, and transfer unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transfer member for an image forming apparatus that suppresses the generation of wrinkles on a recording medium even after repeated image formation.SOLUTION: There is provided a transfer member for an image forming apparatus that is a roll-like or belt-like transfer member and includes a resin layer as an outermost layer, where the resin layer is thicker at both end parts than the center part in the width direction of the transfer member and has a coefficient of friction at both end parts larger than the coefficient of friction at the center part.SELECTED DRAWING: Figure 2

Description

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

  In an electrophotographic image forming apparatus, a cylindrical or annular member is often used, and examples thereof include a photoreceptor, a charging roll, a developing roll, a transfer belt, a transfer roll, and a fixing roll.

For example, Patent Document 1 includes an elastic layer and a surface layer on a base material, and the surface layer has a surface roughness that is rougher at both axial end portions than the axial center portion of the transfer roll. A transfer roll is disclosed in which the thickness is thicker at both axial ends than the axial center of the transfer roll.
Patent Document 2 has a base material containing an elastic material and an outer coating layer containing a resin and covering the outer peripheral surface side of the base material, and the friction coefficient at both ends in the width direction on the inner peripheral surface side of the belt. An endless belt is disclosed that is relatively larger than the coefficient of friction of the portion between the ends.
Patent Document 3 discloses an elasticity formed by using an elastic layer material comprising an isocyanate curing agent, and a rubber material having a functional group capable of reacting with the isocyanate curing agent and a polymerizable unsaturated bond in the molecule. An electrophotographic apparatus member having a layer as an outermost layer and having the elastic layer subjected to a surface treatment is disclosed.

JP 2007-121553 A JP 2014-0667748 A JP 2011-248333 A

  The present invention provides a transfer member for an image forming apparatus that is less likely to wrinkle a recording medium even when image formation is repeated, as compared with the case where the thickness and friction coefficient of the outermost resin layer are the same throughout the entire width direction. The task is to do.

  The above problem is solved by the following means.

The invention according to claim 1
A roll-shaped or belt-shaped transfer member,
It has a resin layer as the outermost layer,
In the width direction of the transfer member, the resin layer has both end portions thicker than the center portion, and the friction coefficient at both end portions is larger than the friction coefficient at the center portion,
A transfer member for an image forming apparatus.

The invention according to claim 2
The resin layer has a sea-island structure, and in the width direction of the transfer member, both of the average diameters of the island portions existing on the outer peripheral surface of the end portion are smaller than the average diameter of the island portions existing on the outer peripheral surface of the central portion. The transfer member according to claim 1.

The invention according to claim 3
The ratio of the maximum thickness in both end portions to the minimum thickness in the central portion (end portion / central portion) of the resin layer is 1.4 or more and 3.0 or less in the width direction of the transfer member. Item 3. The transfer member according to Item 2.

The invention according to claim 4
In the width direction of the transfer member, the resin layer has a ratio (end / center) between the friction coefficient at the position of 5% of the total width from both ends and the friction coefficient at the center (end / center) of 1.3 to 1.6. The transfer member according to any one of claims 1 to 3, wherein

The invention according to claim 5
An image carrier,
Charging means for charging the surface of the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Developing means for developing, as a toner image, an electrostatic charge image formed on the surface of the image carrier with an electrostatic charge image developer containing toner;
Transfer means comprising the transfer member according to any one of claims 1 to 4, and transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
Fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising:

The invention according to claim 6
The image carrier includes: an image carrier; a charging unit that charges the surface of the image carrier; an electrostatic image forming unit that forms an electrostatic image on the charged surface of the image carrier; and an electrostatic image developer containing toner. At least one selected from developing means for developing an electrostatic image formed on the surface of the holding body as a toner image;
Transfer means comprising the transfer member according to any one of claims 1 to 4, and transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
And a process cartridge that is detachably attached to the image forming apparatus.

The invention according to claim 7 provides:
The transfer member according to any one of claims 1 to 4,
An intermediate transfer member disposed to face the transfer member;
A transfer unit that transfers the toner image on the surface of the intermediate transfer member to the surface of the recording medium.

According to the first, third, and fourth aspects of the invention, compared to the case where the thickness and friction coefficient of the resin layer that is the outermost layer are the same throughout the entire width direction, the recording medium is less likely to wrinkle even when image formation is repeated. A transfer member is provided.
According to the second aspect of the present invention, even when the image formation is repeated, the recording medium is wrinkled as compared with the case where the average diameter of the island portion existing on the outer peripheral surface of the resin layer which is the outermost layer is the same in the entire width direction. A difficult transfer member is provided.

According to the fifth aspect of the present invention, compared to the case where the thickness and friction coefficient of the resin layer that is the outermost layer of the transfer member are the same in the entire width direction, the image that hardly causes wrinkles on the recording medium even when the image formation is repeated. A forming apparatus is provided.
According to the sixth aspect of the present invention, compared to the case where the thickness and the friction coefficient of the resin layer that is the outermost layer of the transfer member are the same in the entire width direction, the process that hardly causes wrinkles on the recording medium even when image formation is repeated. A cartridge is provided.
According to the seventh aspect of the present invention, compared to the case where the thickness and the friction coefficient of the outermost resin layer of the transfer member are the same in the entire width direction, the transfer is less likely to cause wrinkles on the recording medium even when image formation is repeated. Units are provided.

It is a schematic sectional drawing which shows the example of the resin layer which the transfer member which concerns on this embodiment has. It is a schematic perspective view which shows an example of the transfer member which concerns on this embodiment. It is a schematic sectional drawing which shows an example of the transfer member which concerns on this embodiment, and is AA sectional drawing of FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus according to an exemplary embodiment.

  Embodiments of the present invention will be described below. These descriptions and examples are illustrative of the invention and are not intended to limit the scope of the invention.

<Transfer member>
The transfer member according to the present embodiment is a roll-like or belt-like transfer member that transfers a toner image on the surface of the opposing member arranged to face the surface of the recording medium.
Specifically, the transfer member according to the present embodiment is, for example, a transfer roll or a transfer belt in an image forming apparatus of a direct transfer type that directly transfers a toner image formed on the surface of an image holding body to a recording medium; In an intermediate transfer type image forming apparatus that primarily transfers a toner image formed on the surface of the body to the surface of the intermediate transfer body and secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium. Secondary transfer roll or secondary transfer belt.

The transfer member according to the present embodiment has a resin layer as the outermost layer. Hereinafter, the outermost resin layer is also referred to as “resin surface layer”. The resin surface layer contacts the back surface of the recording medium (the surface opposite to the surface onto which the toner image is transferred) during image formation.
In the transfer member according to this embodiment, the resin surface layer has both end portions thicker than the center portion in the width direction of the transfer member, and the friction coefficient at both end portions is larger than the friction coefficient at the center portion.

In the transfer member according to the present embodiment, the “width direction” is a direction parallel to the axial direction of the rotation shaft around which the transfer member rotates during image formation.
In the transfer member according to the present embodiment, the “end portion” in the width direction is a region continuous from the end in the width direction of the transfer member, and both end portions are regions of 5% to 15% of the total length in the width direction. Point to. It is desirable that one end and the other end have the same length.
In the transfer member according to the present embodiment, the “central portion” in the width direction is a region including the center in the width direction of the transfer member, and refers to a region between two end portions.

  In the present embodiment, the resin surface layer of the transfer member is always thicker at the both ends than at the center as compared with an arbitrary position at both ends and an arbitrary position at the center. In this case, the thickness of the end portion of the resin surface layer may be constant or may vary within the end portion, and the thickness of the center portion of the resin surface layer may be constant or may vary within the center portion. Good.

Specifically, the thickness of the end portion of the resin surface layer is, for example, the same thickness for the entire end portion; it is thicker continuously or stepwise from the center in the width direction toward the end; There are parts that are thicker or thinner than the surroundings; The thickness of the end portion of the resin surface layer is preferably the same thickness in the entire end portion; or the entire thickness is continuously increased from the center in the width direction toward the end or continuously from the middle. It is good.
Specifically, the thickness of the central portion of the resin surface layer is, for example, the same thickness in the entire central portion; the thickness is continuously or gradually increased from the center in the width direction toward the end side; There are parts that are thicker or thinner than the surroundings; The thickness of the central portion of the resin surface layer is preferably the same thickness in the entire central portion; or the entire thickness is continuously increased from the center in the width direction to the end side or continuously from the middle. It is good.
The thickness of the entire region in the width direction of the resin surface layer is, for example, continuously thick from the center to the end; gradually increased from the center to the end; a combination thereof; Good.
The thickness of the resin surface layer is preferably symmetrical in the width direction.

The friction coefficient of the resin surface layer in this embodiment refers to the static friction coefficient of the outer peripheral surface. The magnitude of the friction coefficient of the resin surface layer in the width direction can be determined by measuring the static friction coefficient at a plurality of positions in the width direction using a portable type friction coefficient measuring device and comparing the measured values.
In the transfer member according to this embodiment, when the friction coefficient is measured at an arbitrary position in both ends and an arbitrary position in the center, the friction coefficient in both ends is always larger than the friction coefficient in the center. As long as this is the case, the friction coefficient at the end of the resin surface layer may be constant or fluctuate within the end, and the friction coefficient at the center of the resin surface layer may be constant or fluctuate within the center. Good.

Specifically, the friction coefficient at the end of the resin surface layer is, for example, the same for the entire end; continuously or gradually increasing from the center in the width direction toward the end; There may be parts that are partially larger or smaller than the surroundings; The size of the coefficient of friction at the end of the resin surface layer is preferably the same for the entire end; or the whole is increased continuously from the center in the width direction toward the end or continuously from the middle. Yes;
Specifically, the friction coefficient at the center of the resin surface layer is, for example, the same for the entire center; continuously or stepwise from the center in the width direction toward the end; in the width direction There may be parts that are partially larger or smaller than the surroundings; The size of the coefficient of friction at the center portion of the resin surface layer is preferably the same at the entire center portion; or the entire surface continuously increases from the center in the width direction toward the end side or continuously from the middle. Yes;
The size of the friction coefficient in the entire width direction of the resin surface layer is, for example, continuously increased from the center toward the end; gradually increased from the center toward the end; a combination thereof; etc. Either of these may be used.
The magnitude of the friction coefficient of the resin surface layer is preferably symmetrical in the width direction.

1A to 1D are schematic cross-sectional views showing examples of the resin surface layer included in the transfer member according to the present embodiment, when the resin surface layer is cut in the width direction and the thickness direction of the transfer member. Shows the cross section that appears.
The resin surface layer shown in FIG. 1 (A) gradually increases in thickness from the center in the width direction toward the end, the entire center portion has the same thickness, and the entire end portion has the same thickness.
In the resin surface layer shown in FIG. 1 (B), the central portion is continuously thicker from the middle toward the end in the width direction, and the end portion of the central portion and the central portion of the end portion are continuous. The whole is the same thickness.
In the resin surface layer shown in FIG. 1C, the entire central portion has the same thickness, the end side of the central portion and the central side of the end portion are continuous, and the end portion extends from the central side in the width direction toward the end. It is continuously thick.
The resin surface layer shown in FIG. 1D is continuously thick from the center in the width direction toward the end, and the end side of the center part and the center side of the end part are continuous.
Below the cross-sectional views of FIGS. 1A to 1D, one or two examples of the coefficient of friction of the resin surface layer in the width direction of the transfer member are shown (change in the coefficient of friction in the width direction). Of course, the method is not limited to these examples). As in these examples, on the outer peripheral surface of the resin surface layer, the friction coefficient at any position in the end portion is larger than the friction coefficient at any position in the central portion.

  In the transfer member according to the present embodiment, both ends of the resin surface layer are thicker than the center, and the friction coefficient at both ends is larger than the friction coefficient at the center. It is hard to generate. The mechanism by which this effect is obtained is not clear, but is presumed as follows.

In the image forming apparatus, a transfer member that constitutes a transfer unit that transfers a toner image to a recording medium forms a nip with a facing member (for example, an image holding member or an intermediate transfer member) arranged to face the transfer member, The recording medium is sandwiched in the nip, and the toner image is transferred from the facing member to the recording medium. The force for ejecting the recording medium from the nip depends on the elasticity of the transfer member, the nip biting, the frictional force between the transfer member and the recording medium, and the recording medium is wrinkled if the recording medium is not smoothly ejected from the nip. Sometimes.
By the way, conventionally, the transfer member has a configuration in which a resin surface layer is provided as the outermost layer for the purpose of imparting smoothness to the surface and for suppressing deterioration of the inner layer due to ozone. When the image formation is repeated (that is, the rotation of the transfer member is repeated), the resin surface layer is repeatedly compressed at the nip and released from the compression on the outer peripheral surface of the transfer member. As a result, cracks (cracks, cracks) may occur in the resin surface layer, and these cracks are likely to occur in the resin surface layer at the end in the width direction where the nip pressure is high. When a crack occurs in the resin surface layer, the nip pressure is reduced at the crack generation site, and the nip pressure varies in the width direction of the transfer member. As a result, the recording medium is not smoothly discharged from the nip, and the recording medium is wrinkled. May occur.
In response to the above event, the transfer member according to the present embodiment suppresses the occurrence of cracks at the end of the resin surface layer when the end of the resin surface layer is thicker than the center. Furthermore, the transfer member according to the present embodiment has an end portion even if a crack is generated at the end portion of the resin surface layer because the friction coefficient at the end portion of the resin surface layer is larger than the friction coefficient at the center portion. The discharge power of the recording medium in the part is maintained, and the generation of wrinkles in the recording medium is suppressed.

Hereinafter, the resin surface layer will be described in detail.
[Resin surface layer]
In the width direction of the transfer member, both end portions of the resin surface layer are thicker than the central portion, and both end portions have a coefficient of friction greater than that of the central portion. The thickness and friction coefficient of the resin surface layer are preferably symmetrical in the width direction.

The thickness of the resin surface layer is selected according to the form of the transfer member, and also from the viewpoint of ensuring surface smoothness, expression of a function to suppress deterioration of the inner layer due to ozone, and wear resistance of the layer. That's fine.
The thickness of the resin surface layer at the end is, for example, preferably from 10 μm to 30 μm, and more preferably from 10 μm to 20 μm.
For example, the thickness of the resin surface layer in the center is preferably 5 μm to 20 μm, and more preferably 5 μm to 12 μm.

  The thickness of the resin surface layer is such that the ratio of the maximum thickness in both end portions to the minimum thickness in the central portion (end portion / center portion) is 1.2 or more and 5.0 from the viewpoint of further suppressing the occurrence of cracks at the end portions. Or less, and more preferably 1.4 or more and 3.0 or less.

The magnitude of the friction coefficient of the resin surface layer may be selected according to the form of the transfer member and the form of the image forming apparatus.
The friction coefficient of the resin surface layer at the end is, for example, 0.5 to 0.9, preferably 0.6 to 0.9, as a static friction coefficient using metal as a mating member.
The coefficient of friction of the resin surface layer in the central portion is, for example, 0.3 to 0.7, preferably 0.4 to 0.6, in terms of a static friction coefficient using metal as a mating member.

  The friction coefficient of the resin surface layer is such that the ratio (end / center) between the larger one of the friction coefficients at the position of 5% of the entire width from both ends (the friction coefficient in the case of being the same) and the center friction coefficient (end / center) is 1. It is preferably 3 or more and 1.8 or less, and more preferably 1.3 or more and 1.6 or less. Within this range, the recording medium is discharged more smoothly and is less likely to wrinkle even when there is no crack at the end or after the crack has occurred at the end.

  For example, the coefficient of friction of the resin surface layer can be controlled in the width direction by changing the composition of the resin material forming the resin surface layer between the end portion and the center portion. In addition, the resin surface layer is formed of a resin material capable of forming a sea-island structure, and the size of the island portion on the outer peripheral surface is controlled according to the conditions during the formation, thereby the friction coefficient of the resin surface layer in the width direction. Can be controlled.

  From the viewpoint of controlling the friction coefficient in the width direction, the resin surface layer has a sea-island structure having a sea part (continuous phase) made of resin and an island part (dispersed phase) made of a resin softer than the resin constituting the sea part. It is desirable to form. In this sea-island structure, it is desirable that both of the average diameters of the island portions existing on the outer peripheral surface of the end portion are smaller than the average diameter of the island portions existing on the outer peripheral surface of the central portion. In this sea-island structure, the friction coefficient of the outer peripheral surface of the resin surface layer tends to increase as the average diameter of the island portion decreases, and decrease as the average diameter of the island portion increases.

In the resin surface layer having the sea-island structure, the average diameter of the island portion on the outer peripheral surface of the end portion is desirably less than 3 μm from the viewpoint of increasing the coefficient of friction than the central portion; From the viewpoint of imparting, it is preferably 0.5 μm or more, and more preferably 1 μm or more.
On the other hand, the average diameter of the island portion on the outer peripheral surface of the central portion is desirably 3 μm or more from the viewpoint of making the friction coefficient smaller than that of the end portion; suppressing uneven distribution and aggregation of the conductive agent (for example, carbon black) However, from the viewpoint of stabilizing the electric resistance, it is preferably not too large, and specifically, it is preferably 5 μm or less.

The average diameter of the island portion on the outer peripheral surface of the resin surface layer refers to the average value of the maximum diameter of the island portion measured as follows.
The resin surface layer is cut out, the outer peripheral surface is ion-etched by Ar gas plasma treatment, and then observed with a scanning electron microscope (SEM).
The ion etching is performed, for example, using RF Plasma Barrel Etcher PT7160 manufactured by Quorum Technologies, with a power of 10 W and a processing time of 8 minutes.
Observation by SEM is performed by using, for example, JSM-6700F manufactured by JEOL Ltd., acceleration voltage: 5 kV, observation mode: secondary electron image (SEI).

In the resin surface layer having the sea-island structure, the occupied area of the island portion at the end is preferably 5% or more and 25% or less, and more preferably 10% or more and 20% or less with respect to the entire outer peripheral surface of the end.
On the other hand, the area occupied by the island part in the central part is preferably 7% or more and 30% or less, and more preferably 12% or more and 25% or less with respect to the entire outer peripheral surface of the central part.
The area occupied by the island is determined by image analysis of the SEM image.

The resin surface layer preferably has a surface roughness of less than 5 μm and more preferably less than 3 μm from the viewpoint of good cleaning by the cleaning member.
The surface roughness of the transfer member is measured by contact-type surface roughness measurement. As a measuring device, Surfcom 570A manufactured by Tokyo Seimitsu Co., Ltd. is used. In the measurement, in accordance with JIS B0601 (2001), the reference length is 2.5 mm, the evaluation length is 12.5 mm, a diamond contact needle (2 μm, 90 ° cone) is used, and the measurement environment is 22 ° C. and 55% humidity. Do.

Next, a method for forming the resin surface layer will be described.
The method for forming the resin surface layer is not particularly limited, but it is possible to easily produce a sea-island structure having a sea part made of resin and an island part made of a resin softer than the resin constituting the sea part. A method using a coating solution containing a resin (curable resin) and an isocyanate compound (curing agent) is desirable. That is, it is desirable that the resin surface layer has a sea-island structure composed of a reaction product of a curable resin and an isocyanate compound.

  The above method includes a coating step of coating a coating liquid containing a curable resin and an isocyanate compound on, for example, an elastic layer, and a drying step of drying while controlling the drying rate of the coating film obtained in the coating step. It is desirable to include at least.

As curable resin contained in a coating liquid, what is necessary is just resin which has a functional group which can react with the isocyanate group in the isocyanate compound which is a hardening | curing agent. Examples of such a resin include polyols such as acrylic polyol, polyester polyol, polyether polyol, polycarbonate polyol, polycaprolactone polyol, and polyolefin polyol having a hydroxyl group in the molecule. Further, for the purpose of improving the function, for example, a fluoroolefin copolymer (for example, a tetrafluoroethylene-vinyl monomer copolymer, a tetrafluoroethylene-alkyl vinyl ether copolymer, etc.), a vinyl fluoride copolymer is used. It may be used.
Examples of commercially available products suitable as the curable resin include Zaffle GK570 (Zeffle is a registered trademark) manufactured by Daikin Industries, Ltd. and Lumiflon (registered trademark) manufactured by Asahi Glass.

  Examples of the isocyanate compound contained in the coating solution include those known as curing agents. Specifically, for example, isocyanurate trimer of hexamethylene diisocyanate (HDI) (commercially available products are Duranate TKA-100, Duranate TPA-100 manufactured by Asahi Kasei Co., Ltd., Takenate D-170N manufactured by Mitsui Takeda Chemicals, Sumika Bayer Urethane. HDI adduct body (commercially available products are Duranate E405-70B, Duranate E402-80B, etc. manufactured by Asahi Kasei Corporation); HDI burette body (commercially available products are Duranate 22A-75P manufactured by Asahi Kasei Corporation). , Duranate 21S-75E, etc.); mixed isocyanurate trimer of HDI and tolylene diisocyanate (TDI) (commercial product is Desmodur HL, etc., manufactured by Sumika Bayer Urethane Co., Ltd.); isocyanurate of isophorone diisocyanate (IPDI) Nurate trimer Commercial products, manufactured by Degussa T1890, etc.); and the like.

The coating solution desirably contains two or more isocyanate compounds, and more desirably contains at least two isocyanate compounds having different compatibility with the curable resin or the solvent. The size of the sea-island structure can be controlled by adjusting the combination of two or more isocyanate compounds and the mixing ratio.
The combination of isocyanate compounds is preferably a combination containing at least two isocyanate compounds having different compatibility with the curable resin or solvent coexisting in the coating solution from the viewpoint of the formation of the sea-island structure. A combination containing at least two isocyanate compounds having different compatibility is more desirable.
Desirable combinations include, for example, a combination of “Duranate 22A-75P” and “Duranate E405-70B”, a combination of “Duranate 21S-75E” and “Duranate E405-70B”, “Duranate TKA-100” and “Duranate”. E402-80B ”,“ Duranate TPA-100 ”and“ Duranate E402-80B ”, and the like.

  In the preparation of the coating liquid, the curable resin (polyol) and the isocyanate compound (curing agent) are the molar ratio of the isocyanate group (NCO group) to the hydroxyl group (OH group) in the curable resin (polyol) (NCO group / OH). Group, R value) in the range of 0.7 to 1.5, preferably in the range of 0.9 to 1.3, more preferably in the range of 1.0 to 1.1. It is good to mix by ratio.

  Examples of the solvent used for preparing the coating solution include butyl acetate, ethyl acetate, butanol and the like. Of these, butyl acetate and ethyl acetate are desirable from the viewpoint of resin solubility and volatility. By adjusting the content of the solvent in the coating solution, the drying time of the coating film (time when the coating film is wet) can be controlled.

The coating solution desirably contains a conductive agent for imparting conductivity to the resin surface layer. Examples of the conductive agent used for the resin surface layer include an electronic conductive agent and an ionic conductive agent. Examples of these conductive agents include the same conductive agents as those described in the elastic layer 113 described later.
Other coating solutions include reaction inhibitors, metal catalysts, surfactants, foam stabilizers, defoamers, flame retardants, plasticizers, softeners, antioxidants, pigments, dyes, stabilizers, antibacterial agents In addition, an additive for controlling physical properties such as a filler may be contained.

  The coating liquid is prepared by dissolving or dispersing the above-described materials in a solvent. At this time, from the viewpoint of enhancing the dispersibility of the conductive agent, it is preferable to use a collision type disperser such as a jet mill or a homogenizer.

  In the coating step, a coating solution is applied, for example, on the elastic layer. In the coating process, a known coating method may be applied depending on the form of the transfer member (for example, a roll member or a belt member). For example, a flow coating method, a dip coating method, a spray coating method, an ink jet method, or the like is applied. The

  In the drying step, the coating film obtained in the coating step is dried while controlling the drying speed. It is possible to control the size of the island part by adjusting the drying speed of the coating film in the drying process, that is, by adjusting the length of time during which the coating film is wet. The longer the time in which the coating film is wet, the larger the size of the island portion, and the shorter the time in which the coating film is wet, the smaller the size of the island portion.

  As a method for adjusting the drying speed, a method of adjusting the drying speed by adjusting the amount of solvent in the coating solution (that is, the amount of solvent in the coating film); changing the temperature and humidity of the environment where the coating film is placed. And adjusting the drying speed; adjusting the drying speed by adjusting the air volume; and combining these.

The coating step and the drying step may be repeated a plurality of times to form the resin surface layer. For example, it is possible to thicken the resin surface layer by repeating the coating step and the drying step at the end portion, and thus the end portion can be made thicker than the central portion.
In addition, as described above, since the size of the island portion tends to be smaller as the time during which the coating film is in a damp state is shorter, for example, 1) 2) The state where the coating film that becomes the outermost surface of the end portion is moistened by reducing the amount of solvent of the coating solution for the coating film that becomes the outermost surface of the end portion to be less than that of the central portion. It is possible to make the time shorter than that of the central part, and make the island part of the outer peripheral surface of the end part smaller than that of the central part, so that the friction coefficient of the end part can be made larger than that of the central part. It is.

  It is desirable to form the resin surface layer through the above steps. In addition, you may baking with respect to the resin surface layer after a drying process as needed.

  The transfer member according to the present embodiment may have a roll shape or a belt shape. The transfer member according to the present embodiment may be applied to a direct transfer type image forming apparatus, or may be applied to an intermediate transfer type image forming apparatus as a secondary transfer member.

Hereinafter, the transfer member according to this embodiment will be described in more detail with reference to FIGS. 2 and 3 by taking as an example a form in which the transfer member according to this embodiment is a transfer roll.
FIG. 2 is a schematic perspective view showing the transfer roll. FIG. 3 is a schematic cross-sectional view of the transfer roll, and is a cross-sectional view taken along the line AA of FIG.

[Transfer roll]
As shown in FIGS. 2 and 3, the transfer roll 111 includes, for example, a cylindrical or columnar support 112, an elastic layer 113 provided on the outer peripheral surface of the support 112, and an outer peripheral surface of the elastic layer 113. And a resin surface layer 114 provided. The transfer roll 111 is not limited to the above configuration, and may be a configuration having an intermediate layer provided between the elastic layer 113 and the support 112, for example.

-Resin surface layer 114-
The resin surface layer 114 is the resin surface layer described above, and a desirable mode is also as described above. Hereinafter, components other than the resin surface layer 114 will be described.

−Support 112−
The support 112 is a conductive member that functions as an electrode and a support member of the transfer roll 111. The support 112 may be a hollow member (cylindrical member) or a non-hollow member.
Examples of the support 112 include metal members such as iron (free-cutting steel, etc.), copper, brass, stainless steel, aluminum, nickel, and the like. Further, examples of the 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.

-Elastic layer 113-
The elastic layer 113 is a conductive layer and includes, for example, a rubber material (elastic material), and may further include a conductive agent and other additives. The elastic layer 113 may be a conductive foamed elastic layer, a conductive non-foamed elastic layer, or a conductive foamed elastic layer and a conductive non-foamed elastic layer. It is desirable that at least the outer peripheral surface of the elastic layer 113 is a conductive non-foamed elastic layer. When the outer peripheral surface is a non-foamed elastic layer, the resin surface layer forming coating liquid is prevented from entering the elastic layer 113 when the resin surface layer 114 is formed.

Examples of the rubber material (elastic material) include an elastic material having a double bond in at least a chemical structure.
Specific rubber materials 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.
The carbon black specifically includes “Special Black 350”, “Special Black 100”, “Special Black 250”, “Special Black 5”, and “Special Black” manufactured by Orion Engineered Carbons. 4 ”,“ Special Black 4A ”,“ Special Black 550 ”,“ Special Black 6 ”,“ Color Black FW200 ”,“ Color Black FW2 ”,“ Color Black FW2V ”,“ MONARCH1000 ”manufactured by Cabot Corporation ”,“ MONARCH1300 ”,“ MONARCH1400 ”,“ MOGUL-L ”,“ REGAL400R ”, and the like.
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 elastic layer 113 is, for example, 5 mm or more and 20 mm or less, and desirably 5 mm or more and 15 mm or less.

-Manufacturing Method of Transfer Roll 111-
First, a roll member in which an elastic layer 113 is provided on the outer peripheral surface of a cylindrical or columnar support 112 is prepared. The manufacturing method of this roll member is not specifically limited. For example, a manufacturing method in which the elastic layer 113 is formed by wrapping a mixture containing a rubber material and, if necessary, a conductive agent and other additives around the support 112 and heating and vulcanizing the mixture.

  The method for providing the resin surface layer 114 on the outer peripheral surface of the elastic layer 113 is not particularly limited, but it is desirable to provide the resin surface layer 114 on the outer peripheral surface of the elastic layer 113 by the method for forming the resin surface layer described above. In addition, for example, a tubular resin member that constitutes the resin surface layer 114 is prepared, and the roll member is inserted into the tubular resin member so that the resin surface layer 114 is provided on the outer peripheral surface of the elastic layer 113. May be.

  The form of the roll member (transfer roll 111) has been described above as an example of the transfer member according to the present embodiment. However, the transfer member according to the present embodiment is not limited thereto, and may be a belt member. When the transfer member according to this embodiment is in the form of a belt member, it may be a belt member in which an elastic layer and a resin surface layer are sequentially laminated, or a base material layer, an elastic layer, and a resin surface layer are sequentially laminated. It may be a belt member.

<Image forming apparatus, process cartridge, transfer unit>
The image forming apparatus according to the present embodiment is an image forming apparatus including a transfer member, and the transfer member according to the present embodiment is applied as the transfer member.
Specifically, for example, the image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges the surface of the image carrier, and an electrostatic charge that forms an electrostatic image on the surface of the charged image carrier. An image forming means, a developing means for developing an electrostatic image formed on the surface of the image carrier as a toner image by an electrostatic charge image developer containing toner, and a toner image formed on the surface of the image carrier are recorded. Transfer means for transferring to a medium, and the transfer means comprises a transfer member according to the present embodiment.

  The image forming apparatus according to the present embodiment is, for example, an apparatus that directly transfers to a recording medium including a transfer roll alone, and includes the transfer member according to the present embodiment as a transfer roll. Alternatively, the image forming apparatus according to the present embodiment includes, for example, an intermediate transfer member to which a toner image formed on the surface of the image carrier is transferred, and a toner image formed on the surface of the image carrier. This is an intermediate transfer type apparatus comprising a primary transfer roll for transferring to the surface and a secondary transfer roll for transferring the toner image transferred to the surface of the intermediate transfer member to a recording medium. The transfer member is provided.

  The image forming apparatus according to the present embodiment includes, for example, a monocolor image forming apparatus in which only a single color toner is accommodated in a developing device; an image forming apparatus that directly transfers a toner image held on an image holding member to a recording medium A color image forming apparatus that repeatedly transfers the toner image held on the image holding member to the intermediate transfer member; a tandem in which a plurality of image holding members each having a developing device for each color are arranged in series on the intermediate transfer member Type color image forming apparatus.

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

  The transfer unit according to the present embodiment is a transfer unit that constitutes a secondary transfer unit of an intermediate transfer type image forming apparatus. The transfer unit according to the present embodiment and an intermediate disposed opposite to the transfer member. And transferring a toner image on the surface of the intermediate transfer member to a recording medium.

  The image forming apparatus according to the present embodiment will be described below with reference to FIG. FIG. 4 is a schematic configuration diagram illustrating an example of an image forming apparatus according to the present embodiment.

  The image forming apparatus illustrated in FIG. 4 is an intermediate transfer type apparatus in which a secondary transfer unit includes a transfer unit (transfer unit according to the present embodiment) including a transfer member according to the present embodiment.

  The image forming apparatus shown in FIG. 4 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 (an example of an image forming unit) are provided. These image forming units (hereinafter simply referred to as “units”) 10Y, 10M, 10C, and 10K are juxtaposed in the horizontal direction so as to be separated from each other. Note that 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 (an example of an intermediate transfer member) is extended through each unit. The intermediate transfer belt 20 is wound around a drive roll 22 and a back roll 24 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 vehicle travels in the direction from the unit 10Y to the fourth unit 10K. The back roll 24 is biased in a direction away from the drive roll 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around both. An intermediate transfer member cleaning device 30 is provided on the outer peripheral surface of the intermediate transfer belt 20 so as to face the drive roll 22.
Each of the developing devices 4Y, 4M, 4C, and 4K (an example of the developing unit) of the units 10Y, 10M, 10C, and 10K includes yellow, magenta, cyan, and black contained in the toner cartridges 8Y, 8M, 8C, and 8K. Each toner is supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K 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.

The first unit 10Y has a photoreceptor 1Y (an example of an image holding member). Around the photoreceptor 1Y, there are a charging roll 2Y for charging the surface of the photoreceptor 1Y, an exposure device 3 for exposing the charged surface with a laser beam 3Y based on the color-separated image signal to form an electrostatic image, A developing device 4Y (an example of a developing unit) that supplies toner to the charge image to develop the electrostatic image, a primary transfer roll 5Y (an example of a primary transfer unit) that transfers the developed toner image onto the intermediate transfer belt 20, and a primary A photoreceptor cleaning device 6Y (an example of a cleaning unit) that removes toner remaining on the surface of the photoreceptor 1Y after the transfer is sequentially arranged.
The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20, and is provided at a position facing the photoreceptor 1Y. Bias power supplies (not shown) for applying a primary transfer bias are connected to the primary transfer rolls 5Y, 5M, 5C, and 5K, respectively. 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 about −600V to −800V 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 is formed on the surface of the photoreceptor 1Y.

In the electrostatic charge image, the specific resistance of the irradiated portion of the photosensitive layer is lowered by the irradiation of the laser beam 3Y, the charge on the surface of the photoreceptor 1Y flows, while the charge of the portion not irradiated with the laser beam 3Y remains. It is a so-called negative latent image formed by
The electrostatic charge image formed on the photoreceptor 1Y rotates to the developing position as the photoreceptor 1Y travels, and is visualized (developed) by the developing device 4Y at the developing position.

  A developer containing at least yellow toner and a carrier 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 charge on the photoreceptor 1Y and is held on the developer roll (developer holder). Has been. As the surface of the photoreceptor 1Y passes through the developing device 4Y, 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, and the yellow toner image developed on the photoreceptor 1Y is conveyed to the primary transfer position.

When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer position, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force directed from the photoreceptor 1Y to the primary transfer roll 5Y acts on the toner image, and the photosensitive member 1Y The toner image on the body 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 about +10 μA by the control unit (not shown) in the first unit 10Y.
The toner remaining on the photoreceptor 1Y is removed and collected by the cleaning device 6Y.

  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 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 10Y.

  The intermediate transfer belt 20 onto which the four color toner images are transferred in multiple times through the first to fourth units reaches the secondary transfer portion. The secondary transfer unit includes an intermediate transfer belt 20, a back roll 24 in contact with the inner surface of the intermediate transfer belt 20, and a secondary transfer roll 26 (an example of a secondary transfer unit, a main transfer unit disposed on the outer peripheral surface side of the intermediate transfer belt 20. Transfer member according to the embodiment).

  In the secondary transfer portion, when the recording paper P (an example of a recording medium) is supplied to the gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are pressed, the secondary transfer bias is applied to the back roll 24. Is done. The secondary transfer bias has the same polarity (−) as the polarity (−) of the toner, and electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, and the toner image on the intermediate transfer belt 20 is recorded. Transferred onto the paper 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 paper P is sent to a fixing device 28 (an example of fixing means), and the toner image is heated, and the color-superposed toner image is melted and fixed on the recording paper P. The recording paper P on which the color image has been fixed is conveyed to the discharge unit, and a series of color image forming operations is completed.

  Examples of the recording paper P on which the toner image is transferred include plain paper used in electrophotographic copying machines, printers, and the like. In addition to the recording paper P, an OHP sheet or the like may be applied as a recording medium.

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” and “%” are based on mass unless otherwise specified.

<Example 1>
[Production of roll with foamed elastic layer]
60 parts of epichlorohydrin rubber (Epichromer CG-102 manufactured by Daiso Corporation) excellent in ion conductivity and 30 parts of acrylonitrile-butadiene rubber (Nipol DN-219 manufactured by Nippon Zeon Co., Ltd.) are mixed and sulfur (200 mesh manufactured by Tsurumi Chemical Co., Ltd.) is mixed. 1 part, 1.5 part of a vulcanization accelerator (Ouchi Shinsei Chemical Industry Noxeller M) and 6 parts of benzenesulfonylhydrazide as a foaming agent were added and kneaded with an open roll to obtain a mixture. . Next, this mixture was wound around a shaft (support) made of SUS having a diameter of 12 mm and a length of 350 mm. The SUS shaft was heated to 160 ° C. as a heat source, and the wound mixture was vulcanized and foamed to form a foamed elastic layer on the support. The outer peripheral surface of this foamed elastic layer was polished to an outer diameter of 28 mm (the thickness of the foamed elastic layer was 8 mm).

[Formation of non-foamed elastic layer]
60 parts of epichlorohydrin rubber (Epichromer CG-102 manufactured by Daiso Corporation) and 30 parts of acrylonitrile-butadiene rubber (Nipol DN-219 manufactured by Nippon Zeon Co., Ltd.) excellent in ion conductivity are mixed and sulfur (200 mesh manufactured by Tsurumi Chemical Co., Ltd.) is mixed. 1 part and 1.5 parts of a vulcanization accelerator (Okusaka Chemical Co., Ltd. Noxeller M) were added and kneaded with an open roll to obtain a mixture. Next, this mixture was wound around a shaft made of SUS having a diameter of 24 mm. As a heat source, the temperature of the SUS shaft was raised to 160 ° C., the wound mixture was vulcanized, and then the outer peripheral surface was polished to an outer diameter of 26 mm to obtain a rubber tube. This rubber tube was covered with a roll with a foamed elastic layer, and a non-foamed elastic layer was provided on the foamed elastic layer to obtain a roll with an elastic layer.

[Formation of resin surface layer]
A curable resin (Zeffle GK-570 (Zeffle is a registered trademark) manufactured by Daikin Industries, Ltd., solid content: 60%) was diluted with butyl acetate so that the solid content was 20%. In this diluted solution, 20 parts of carbon black (Special Black 4A, manufactured by Orion Engineered Carbons, average particle diameter (arithmetic average diameter obtained by observing particles with an electron microscope) 25 nm) per 100 parts of curable resin Was added and dispersed with a jet mill disperser (Geanus PY manufactured by Genus) (pressure 200 N / mm ² , number of collisions 5 passes) to obtain a resin liquid.
With respect to 100 parts of this resin liquid, 21.4 parts of Duranate TKA-100 (manufactured by Asahi Kasei) (liquid diluted with butyl acetate to a solid content of 10%) as a curing agent and Duranate E402-80B (manufactured by Asahi Kasei) ) (Liquid diluted with butyl acetate to a solid content of 40%) 13.5 parts were mixed. Thereafter, 10 parts of butyl acetate was added to obtain a coating solution for forming a resin surface layer.

  A coating solution for forming a resin surface layer was spray-coated on the entire outer peripheral surface of a roll with an elastic layer (total length 350 mm), and dried to form a resin surface layer having a thickness of 8 μm. On the outer side in the axial direction from the width of 260 mm at the center of the roll, the above operation was repeated three more times to thicken the resin surface layer by 2 μm each time, thereby forming a resin surface layer having a total thickness of 14 μm. Then, it heated and baked at 140 degreeC for 20 minutes. The rubber parts at both ends were cut off by 15 mm to obtain a transfer roll having a rubber part having a length of 320 mm (end part: 30 mm × 2, central part: 260 mm).

<Example 2>
A transfer roll was obtained in the same manner as in Example 1 except that the end thickening operation (2 μm at a time) was repeated twice to change the total thickness of the end to 12 μm.

<Example 3>
The coating solution for forming the resin surface layer was prepared without adding 10 parts of butyl acetate, and the operation of thickening the edges (2 μm at a time) was repeated twice to change the total thickness of the edges to 12 μm. A transfer roll was obtained in the same manner as in Example 1 except that.

<Comparative Example 1>
Except that the center part of the roll formed a resin surface layer with a thickness of 8 μm in one operation, and the end part was divided into four operations (2 μm at a time) to form a resin surface layer with a thickness of 8 μm. In the same manner as in Example 1, a transfer roll was obtained.

<Comparative Example 2>
The central part of the roll formed a resin surface layer having a thickness of 8 μm by one operation, and the end part was divided into two operations (6 μm for the first time and 8 μm for the second time) to form a resin surface layer having a total thickness of 14 μm. Except for the above, a transfer roll was obtained in the same manner as in Example 1.

<Comparative Example 3>
The central part of the roll formed a resin surface layer having a thickness of 8 μm by one operation, and the end part was divided into two operations (4 μm for the first time and 8 μm for the second time) to form a resin surface layer having a total thickness of 12 μm. Except for the above, a transfer roll was obtained in the same manner as in Example 1.

<Comparative example 4>
A transfer roll was obtained in the same manner as in Example 1 except that a resin surface layer having a thickness of 8 μm was formed on the entire roll by one operation.

<Measurement>
[Average diameter of island part on outer peripheral surface of resin surface layer]
The measurement was performed according to the method described above.

[Coefficient of friction]
Place the transfer roll in an environment of 22 ° C. and 55% humidity for 6 hours or longer, and use the tribogear muse TYPE: 94i-II manufactured by Shinto Kagaku Co., Ltd. as a friction coefficient measurement device in the same environment. (Brass, hard chrome treatment) was brought into contact with the transfer roll, and the static friction coefficient was measured. In the axial direction of the transfer roll, the coefficient of static friction was measured at 5% of the full width from both ends, at four locations every 30 mm from both ends, and at the center position, and the friction coefficient at the end and the center was confirmed. .
Table 1 below shows the larger one of the values measured at the position of 5% of the full width from both ends and the value measured at the center position.

<Evaluation>
The transfer roll of each Example and each comparative example was attached as a secondary transfer roll to a secondary transfer unit of 700 Digital Color Press manufactured by Fuji Xerox Co., Ltd. Using this image forming apparatus, 600,000 sheets of comprehensive patterns with characters and patches were formed using ColorCopy paper (A3 paper, basis weight 160 g / m ² ) manufactured by Fuji Xerox Co., Ltd., and the following evaluation was performed. . Image formation was performed in an environment of a temperature of 10 ° C. and a humidity of 15% under the conditions of a process speed of 440 mm / sec, a secondary transfer current of 100 μA, and a load at the center of the secondary transfer roll of 50 mN / mm ² .

[crack]
The outer peripheral surface of the secondary transfer roll was observed with the naked eye every time 50,000 sheets of image formation were completed, and the presence or absence of occurrence of cracks was determined.

[Wrinkles of recording medium (paper wrinkles)]
Every 50,000 sheets of imaged paper were observed with the naked eye to determine the presence or absence of wrinkles. When no wrinkle was observed up to 600,000 sheets, it was determined as “not generated”.

[stress]
Using a load measuring device MODEL-1605N manufactured by Aiko Engineering Co., Ltd., an indenter having a diameter of 10 mm was pushed into the transfer roll at a speed of 10 mm / min, and the force (N) at the time of pushing 1 mm was used as the stress. The measurement positions were a position of 5% of the full width from one end and a center position in the axial direction of the transfer roll. The measurement was performed in an environment of 23 ° C. ± 5 ° C.
Note that the decrease in stress indicates a decrease in the force for feeding the paper of the transfer roll.

  The measurement results and evaluation results are shown in Table 1 below. In Table 1, “before run” means before image formation, and “after run” means after image formation of 600,000 sheets.

As can be seen from Comparative Examples 1 to 4, paper wrinkles are generated in connection with the occurrence of cracks at the end of the transfer roll.
As can be seen from Comparative Examples 2 to 4, the thinner the end of the transfer roll, the faster the crack is generated at the end of the transfer roll.

  As can be seen from the comparison between Example 1 and Comparative Example 1, when the end portion of the transfer roll is thicker than the center portion, occurrence of cracks at the end portion of the transfer roll is suppressed.

As can be seen from the comparison between Example 1 and Comparative Example 2 and the comparison between Example 2 and Comparative Example 3,
Even if a crack occurs at the end of the transfer roll, if the friction coefficient at the end is greater than the friction coefficient at the center, the occurrence of paper wrinkles after the crack is generated is suppressed.

111 Transfer Roll 112 Support 113 Elastic Layer 114 Resin Surface Layer

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 device 8Y, 8M, 8C, 8K Toner cartridge 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt 22 Drive roll 24 Back roll 26 Secondary transfer roll 28 Fixing device 30 Intermediate transfer member cleaning apparatus

Claims (7)

A roll-shaped or belt-shaped transfer member,
It has a resin layer as the outermost layer,
In the width direction of the transfer member, the resin layer has both end portions thicker than the center portion, and the friction coefficient at both end portions is larger than the friction coefficient at the center portion,
A transfer member for an image forming apparatus.   The resin layer has a sea-island structure, and in the width direction of the transfer member, both of the average diameters of the island portions existing on the outer peripheral surface of the end portion are smaller than the average diameter of the island portions existing on the outer peripheral surface of the central portion. The transfer member according to claim 1.   The ratio of the maximum thickness in both end portions to the minimum thickness in the central portion (end portion / central portion) of the resin layer is 1.4 or more and 3.0 or less in the width direction of the transfer member. Item 3. The transfer member according to Item 2.   In the width direction of the transfer member, the resin layer has a ratio (end / center) between the friction coefficient at the position of 5% of the total width from both ends and the friction coefficient at the center (end / center) of 1.3 to 1.6. The transfer member according to any one of claims 1 to 3, wherein An image carrier,
Charging means for charging the surface of the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Developing means for developing, as a toner image, an electrostatic charge image formed on the surface of the image carrier with an electrostatic charge image developer containing toner;
Transfer means comprising the transfer member according to any one of claims 1 to 4, and transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
Fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising: The image carrier includes: an image carrier; a charging unit that charges the surface of the image carrier; an electrostatic image forming unit that forms an electrostatic image on the charged surface of the image carrier; and an electrostatic image developer containing toner. At least one selected from developing means for developing an electrostatic image formed on the surface of the holding body as a toner image;
Transfer means comprising the transfer member according to any one of claims 1 to 4, and transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
And a process cartridge that is detachably attached to the image forming apparatus. The transfer member according to any one of claims 1 to 4,
An intermediate transfer member disposed to face the transfer member;
A transfer unit that transfers the toner image on the surface of the intermediate transfer member to the surface of the recording medium.