JP7287071B2 - ELASTIC FOAM MEMBER, TRANSFER DEVICE, PROCESS CARTRIDGE, AND IMAGE FORMING APPARATUS - Google Patents

Description

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

Electrophotographic image forming apparatuses such as copiers and printers (also referred to as electrophotographic apparatuses or electrophotographic image forming apparatuses) often use conductive rubber rolls such as charging rolls, transfer rolls, and developing rolls. These rubber rolls are required to maintain a uniform nip width when in contact with the photoreceptor in order to respond to high-speed equipment and high image quality. It is desired that the foam cells be dense and uniform.

For example, Patent Document 1 discloses a thermoplastic resin foam sheet having a sheet-like material laminated on at least one side, wherein the ratio Dz of the diameter Dz of the cells in the thickness intermediate layer in the thickness direction to the diameter Dxy of the cells in the in-plane direction /Dxy is an average of 2.0 or more, and the ratio Dz/Dxy of the cells in the surface layer on which the sheet-like material is laminated is an average of less than 1.5. there is

Further, Patent Document 2 describes a foam made of a polyolefin resin having a bending stiffness of 6000 to 14000 kgf/cm ² in a bending test (JIS K 7106 (1982)), and a compression test (JIS K 6767 (1976)) has (1) a yield point and is obtained from the equation (2) [P(%) = (yield strength/stress at 50% strain) x 100]. (3) compression energy loss at 50% strain is 85-100%, and the cells contained within the foam are perpendicular to the top and bottom surfaces of the foam which are parallel to each other; Disclosed is a polyolefin resin foam characterized by having an elliptical shape such that the cell diameter in a direction (hereinafter referred to as the thickness direction of the foam) is larger than the cell diameter in the direction orthogonal to the direction. there is

JP-A-11-291374 JP-A-10-219017

The problem to be solved by the present invention is that in a cross section of the foamed elastic layer cut along a plane perpendicular to the axial direction of the conductive substrate, the thickness direction of the foamed elastic layer is the y-axis, and the y-axis in the cross section is , the maximum length of the cells in the foamed elastic layer in the x-axis direction is X, and the maximum length in the y-axis direction is Y, the average value of the X/Y values is 0 To provide a foamed elastic member having a small compression set even when stored for a long time (48 hours) in a high-temperature and high-humidity environment (60° C., 95% RH) compared to a case where the compression set is less than .86 or more than 1.16. is.

Specific means for solving the above problems include the following aspects.
<1> It has a conductive substrate and a foamed elastic layer disposed on the conductive substrate, and in a cross section of the foamed elastic layer cut in the thickness direction of the foamed elastic layer, the foamed The thickness direction of the elastic layer is the y-axis, the direction perpendicular to the y-axis in the cross section is the x-axis, the maximum length of the cells in the foamed elastic layer in the x-axis direction is X, and the maximum length of the cells in the y-axis direction is X. A foamed elastic member having an average value of X/Y, where Y is 0.86 or more and 1.16 or less.
<2> The foamed elastic member according to <1>, wherein the foamed elastic layer contains epichlorohydrin rubber, and the liberation amount of chlorine ions is 1 μg/g or more and 80 μg/g or less.
<3> The foamed elastic member according to <1> or <2>, wherein the average cell-to-cell distance calculated by the L function in the foamed elastic layer is 320 μm or more and 600 μm or less.
<4> The foamed elastic member according to <3>, wherein the average cell-to-cell distance calculated by the L function in the foamed elastic layer is 400 μm or more and 520 μm or less.
<5> The elastic foam member according to any one of <1> to <4>, which has a roller shape.
<6> The initial outer diameter of the foamed elastic member is Da, and the outer diameter of the foamed elastic member after being left in an environment of 60°C and 85% RH for 48 hours and then in an environment of 22°C and 55% RH for 24 hours. The foamed elastic member according to <5>, wherein the value of Da-Db is less than 521 μm when Db.
<7> The foamed elastic layer was left in an environment of 60°C and 85% RH for 48 hours in a state in which the foamed elastic layer was cut into a flat metal plate having a thickness of 8.0 mm by 0.6 mm, and then was placed in an environment of 22°C and 55% RH for 24 hours. Any one of <1> to <6>, wherein the deformation amount of the outer diameter of the foamed elastic member at the portion where the metal flat plate is bitten is less than 225 μm, measured after 30 minutes after the metal flat plate is left for a certain period of time. 1. The foamed elastic member according to claim 1.
<8> A transfer device comprising the foamed elastic member according to any one of <1> to <7> as a transfer member for transferring a transfer material to a transfer target.
<9> A process cartridge including the transfer device according to <8> and detachable from an image forming apparatus.
<10> An image carrier, a charging device that charges the surface of the image carrier, an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged image carrier, and a developer containing toner a developing device for developing an electrostatic latent image formed on the surface of the image carrier to form a toner image; and a transfer device according to <8> for transferring the toner image to the surface of a recording medium; An image forming apparatus comprising:

According to the invention according to <1> or <5>, in a cross section of the foamed elastic layer cut along a plane perpendicular to the axial direction of the conductive substrate, the thickness direction of the foamed elastic layer is the y-axis, The value of X/Y where the direction perpendicular to the y-axis in the cross section is the x-axis, the maximum length of the cells in the foamed elastic layer in the x-axis direction is X, and the maximum length in the y-axis direction is Y. is less than 0.86 or more than 1.16.
According to the invention according to <2>, compared to the case where the foamed elastic layer contains epichlorohydrin rubber and the liberation amount of chlorine ions is less than 1 μg/g or more than 80 μg/g, under a high-temperature and high-humidity environment, A foamed elastic member having a smaller compression set is provided even after long-term storage.
According to the invention according to <3>, compared to the case where the average cell-to-cell distance calculated by the L function in the foamed elastic layer is less than 320 μm or more than 600 μm, even after long-term storage in a high-temperature and high-humidity environment, A foamed elastic member having a lower compression set is provided.
According to the invention according to <4>, compared to the case where the average cell-to-cell distance calculated by the L function in the foamed elastic layer is less than 400 μm or more than 520 μm, even after long-term storage in a high-temperature and high-humidity environment, A foamed elastic member having a lower compression set is provided.
According to the invention according to <6>, the initial outer diameter of the foamed elastic member is Da, and after being left in an environment of 60° C. and 85% RH for 48 hours, and then left in an environment of 22° C. and 55% RH for 24 hours. In the case of the outer diameter Db of the foamed elastic member, compared to the case where the value of Da - Db is 521 μm or more, the foamed elastic member has a smaller compression set even after long-term storage in a high-temperature and high-humidity environment. provided.
According to the invention according to <7>, a metal flat plate having a thickness of 0.6 mm is bitten into the foamed elastic layer, and after being left for 48 hours in an environment of 60°C and 85% RH, After the metal flat plate was left for 24 hours in an RH environment, the deformation amount of the outer diameter of the foamed elastic member at the portion where the metal flat plate was cut into was measured after 30 minutes, and was 225 μm or more. Provided is a foamed elastic member having a smaller compression set even when stored for a long period of time in a high-temperature and high-humidity environment.
According to the above <8> to <10>, in the cross section of the foamed elastic layer cut along a plane perpendicular to the axial direction of the conductive base material in the foamed elastic member, the thickness direction of the foamed elastic layer is the y-axis, the direction perpendicular to the y-axis in the cross section is the x-axis, the maximum length of the cells in the foamed elastic layer in the x-axis direction is X, and the maximum length in the y-axis direction is Y, then X A transfer device comprising a foamed elastic member having a small compression set even when stored for a long period of time in a high-temperature and high-humidity environment, compared to when the average value of /Y is less than 0.86 or more than 1.16, A process cartridge or image forming apparatus is provided.

1 is a schematic configuration diagram showing an example of an image forming apparatus according to an embodiment; FIG.

An embodiment, which is an example of the present invention, will be described in detail below.
In this specification, when there are multiple types of substances corresponding to the component, the amount of the component means the total amount of the multiple types of substances unless otherwise specified.
As used herein, the term “conductivity” means that the volume resistivity in a normal temperature and normal humidity environment (22° C., 55% RH environment) is 10 ¹⁴ Ω·cm or less.

<Foamed elastic member>
A foamed elastic member according to the present embodiment has a conductive base material and a foamed elastic layer disposed on the conductive base material, and the foamed elastic layer is cut along the thickness direction of the foamed elastic layer. In the cross section of the layer, the thickness direction of the foamed elastic layer is the y-axis, the direction perpendicular to the y-axis in the cross section is the x-axis, and the maximum length of the cells in the foamed elastic layer in the x-axis direction is X and y. When the maximum length in the axial direction is Y, the average value of X/Y is 0.86 or more and 1.16 or less.
The foamed elastic member according to this embodiment is preferably roller-shaped.
Further, the foamed elastic member according to the present embodiment is suitably used for electrophotographic apparatus rolls such as charging rolls, transfer rolls, developing rolls, and power supply rolls.
Among these, it is particularly preferably used for the transfer roll.
Furthermore, it is preferable that the foamed elastic member according to the present embodiment is a conductive roll.

In recent years, electrophotographic image forming apparatuses are required to have high image quality and high reliability. Also, the shape of cells in the foamed elastic member may change due to compressive strain.
Due to the above configuration, the foamed elastic member according to the present embodiment has a small compression set even when stored for a long period of time (48 hours) in a high-temperature and high-humidity environment (60° C., 95% RH). Although the reason for this is not clear, it is presumed to be due to the following reasons.
By setting the average value of the X/Y values in the foamed elastic layer to 0.86 or more and 1.16 or less, the shape of the cells in the foamed elastic layer becomes nearly spherical, and the foamed elastic layer The dispersibility of the cells is also excellent in the high-temperature and high-humidity environment. It is possible to obtain a foamed elastic member with little compression set even when stored for a long period of time in a moist environment.
In addition, in this embodiment, the said effect is also called "time-dependent distortion suppression property."

Further, in the foamed elastic member according to the present embodiment, the average value of the X/Y values in the foamed elastic layer is 0.86 or more and 1.16 or less, so that the shape of the cells in the foamed elastic layer is Since it becomes nearly spherical and has excellent dispersibility of cells in the foamed elastic layer, it has excellent shape stability even in a high-temperature and high-humidity environment. Little change (hereinafter also referred to as "outer diameter stability over time").

Details of the foamed elastic member according to the present embodiment will be described below.

(Conductive substrate)
The foamed elastic member according to this embodiment has a conductive base material.
Examples of conductive substrates include metals or alloys such as aluminum, copper alloys, and stainless steel; iron plated with chromium, nickel, etc.; and substrates made of conductive materials such as conductive resins. Used.

Suitable examples of conductive substrates include metal members such as iron (free-cutting steel, etc.), copper, brass, stainless steel, aluminum, and nickel.
Examples of conductive substrates include members whose outer surfaces are plated (eg, resin and ceramic members), members in which a conductive agent is dispersed (eg, resin and ceramic members), and the like.
Furthermore, the conductive substrate may be a hollow member (cylindrical member) or a non-hollow member.
Moreover, the size and shape of the conductive substrate are not particularly limited, and may be appropriately set according to the desired application.

(Foam elastic layer)
A foamed elastic member according to the present embodiment has a foamed elastic layer disposed on the conductive base material, and in a cross section of the foamed elastic layer cut in the thickness direction of the foamed elastic layer, the The thickness direction of the foamed elastic layer is defined as the y-axis, the direction perpendicular to the y-axis in the cross section is defined as the x-axis, the maximum length of the cells in the foamed elastic layer in the x-axis direction is defined as X, and the maximum length in the y-axis direction is defined as is Y, the average value of X/Y is 0.86 or more and 1.16 or less.

-Ratio of X/Y-
In the foamed elastic layer, the average value of X/Y values is It is from 0.86 to 1.16, preferably from 0.90 to 1.15, and from 1.00 to 1.14, from the viewpoint of the ability to suppress distortion over time and the stability of the outer diameter over time. 1.00 or more and 1.10 or less is particularly preferable.
In addition, from the viewpoint of the ability to suppress distortion over time and the stability of the outer diameter over time, the average value of X is preferably equal to or less than the average value of Y.

The measurement and calculation of the X/Y ratio shall be performed by the method shown below.
Using a razor, cross sections in a direction perpendicular to the surface direction of the foamed elastic layer are prepared at four locations of 90° in the central portion of the foamed elastic layer.
The cross-sectional shape is observed using a laser microscope VK-X200 manufactured by Keyence Corporation to obtain a cross-sectional image of foaming. At this time, observation with a laser microscope is performed at a magnification at which a foamed shape can be obtained.
The resulting image was introduced into Image-Pro Plus, an image analysis software manufactured by Media Cybernetics, and the aspect ratio (X/Y ratio) of the cells (foam structure) in the foamed elastic layer was measured for 100 or more cells. and calculate the average value.

－Definition of Cell Uniformity－
Since the cells of the foamed elastic layer are present in the foamed elastic layer with a nearly uniform distribution, the distortion over time and the stability of the outer diameter over time are improved. As indicators of cell uniformity, the particle size obtained by approximating a cell with a circle, the cell number density calculated from the number of cells included in the measurement area, and the barycentric coordinate point of another cell from the barycentric coordinate point when the cell is approximated by a circle. They are the average distance between cells, which is the average value of the distances to cells, the Morishita index, the L function, and the like, which represent the state of dispersion.
Image analysis can be performed using commercially available analysis software, and is not limited as long as necessary analysis can be performed.

In this embodiment, Ripley's L function is used as the L function.
The Ripley's L function used in this embodiment will be described below.
First, Ripley's K function is defined as follows.
K(d)=E/ρ
E is the barycentric coordinate point when approximating other cells contained within a circle with a radius d centered at the barycentric coordinate point when a cell selected at random in the cross section of the foamed elastic layer is approximated by a circle. and ρ is the cell number density (average density) in the cross section of the foamed elastic layer
In other words, K(d), which is the K function, is the average number of center-of-gravity coordinate points when approximating other cells contained within a circle of radius d centered at a randomly selected point with a circle. It is a value divided by the cell number density ρ (average density) in the layer. It is known that a random distribution of points on a finite plane follows a Poisson distribution. If the barycentric coordinate points are randomly distributed according to the Poisson distribution, the expected value of the number of barycentric coordinate points when approximating other cells existing in a circle of radius d with a circle is given by the average density ρ Since it is a value obtained by multiplying the area of the circle πd ^{by 2} , it is represented by the following formula (K).

Here, the L function is a linear function obtained by standardizing the K function. L(d), which is the L function, is represented by the following formula (L).

Considering the index of the L function, L(d)=0 when the barycentric coordinate points are randomly distributed regardless of the radius d. L(d) takes a positive value when the spatial distribution is a concentrated distribution, and takes a negative value when it is a regular distribution (constant interval distribution).

The inventors of the present invention have investigated the relationship between various indices relating to cell uniformity, strain over time, and outer diameter stability over time. The distance defined by the L function in the foamed elastic layer shall be measured and calculated by the following method. The obtained image was introduced into the image analysis software Image-Pro Plus manufactured by Media Cybernetics, and the X/Y value of the foamed elastic layer was measured. Measured for 100 or more cells (foam structure) in the cross section. And the position data are calculated, then the position data are evaluated by the L function, and the value with the largest L value is taken as the average inter-cell distance.

In the foamed elastic layer, the average cell-to-cell distance calculated by the L function is preferably 300 μm or more and 650 μm or less, and more preferably 320 μm or more and 600 μm or less, from the viewpoints of strain suppression over time and outer diameter stability over time. is more preferable, and 400 μm or more and 550 μm or less is particularly preferable.

-Elastic material-
The foamed elastic layer preferably contains an elastic material.
A rubber material is preferably used as the elastic material.
Specific examples include isoprene rubber, chloroprene rubber, epichlorohydrin rubber (ECO), butyl rubber, urethane rubber, silicone rubber, fluororubber, 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 rubber (EPDM), acrylonitrile-butadiene copolymer rubber (NBR), natural rubber, and rubber mixtures thereof.
Among these, urethane rubber or epichlorohydrin rubber is preferably included, and epichlorohydrin rubber is particularly preferably included, from the viewpoints of resistance maintenance, strain suppression over time, and outer diameter stability over time. Epichlorohydrin rubber is also a conductive compound, which will be described later.
The content of the epichlorohydrin rubber with respect to 100 parts by mass of the elastic material in the foamed elastic layer is preferably 10 parts by mass or more and 100 parts by mass or less, more preferably 20 parts by mass or more and 100 parts by mass or less, and 30 parts by mass from the viewpoint of resistance maintenance. 100 parts by mass or less is more preferable, 40 parts by mass or more and 100 parts by mass or less is particularly preferable, and 50 parts by mass or more and 100 parts by mass or less is most preferable.

Examples of epichlorohydrin rubber include epichlorohydrin homopolymer rubber, copolymer rubber (epichlorohydrin-ethylene oxide copolymer rubber, epichlorohydrin-allyl glycidyl ether copolymer rubber, epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer rubber, etc.), and mixtures thereof. Rubber etc. are mentioned.

The elastic material may be used singly or in combination of two or more.
The content of the elastic material in the foamed elastic layer is preferably 30% by mass or more and 90% by mass or less, more preferably 40% by mass or more and 80% by mass, based on the total mass of the foamed elastic layer, from the viewpoint of resistance maintenance. It is more preferably 50% by mass or more and 70% by mass or less.
In addition, the content of the resin component in the foamed elastic layer is preferably 30% by mass or more and 100% by mass or less, more preferably 40% by mass or more and 100% by mass, based on the total mass of the foamed elastic layer, from the viewpoint of resistance maintenance. It is more preferably not more than 50% by mass, and still more preferably 50% by mass or more and 100% by mass or less.

- Amount of liberated chlorine ions -
When the foamed elastic layer contains epichlorohydrin rubber, the liberated amount of chloride ions in the foamed elastic layer is 0.5 μg/g or more and 100 μg/g or less from the viewpoint of temporal distortion suppression and temporal outer diameter stability. is more preferably 1 μg/g or more and 80 μg/g or less, more preferably 5 μg/g or more and 60 μg/g or less, and particularly 10 μg/g or more and 40 μg/g or less preferable.
In order to keep the liberated amount of chloride ions in the conductive elastic layer within the above range, the introduction of washing, lowering of the vulcanization temperature, etc. are preferably utilized. For example, when the washing time and the drying time after washing are lengthened, the liberated amount of chlorine ions tends to decrease. Further, when the vulcanization temperature for forming the conductive elastic layer is lowered, the liberated amount of chlorine ions tends to decrease.
In addition, the “chlorine ion” in the present embodiment means an ion containing a chlorine atom, and includes chloride ion, hypochlorite ion, and the like.

A method for measuring the amount of chlorine ions liberated in the foamed elastic layer is as follows.
A 0.5 g sample is collected from the foamed elastic layer of the foamed elastic member. A 0.5 g sample is put into a resin container, 100 mL of ultrapure water (0.058 μS/cm) is added to the resin container, and the sample is immersed for 30 minutes to extract ion components. The extract is diluted 50-fold and injected into ion chromatography (ICS-2100 manufactured by Thermo Fisher Scientific) to measure chloride ions. The column is AS-19 (manufactured by Thermo Fisher Scientific), the eluent is potassium hydroxide, and the liquid is sent at a flow rate of 1.0 mL/min. Then, using an electrical conductivity detector, chloride ions are quantified by an absolute calibration curve method using a mixed standard solution containing chloride ions (manufactured by Kanto Chemical Co., Ltd., anion mixed standard solution I), and the amount of chloride ions is determined. demand.
This operation is performed on three types of samples taken from both ends and the central portion of the foamed elastic layer in the thickness direction of the foamed elastic member, and the amount of chloride ions is obtained, and the average value is taken as the liberated amount of chloride ions.

- Conductive compound -
The foamed elastic layer preferably contains a conductive compound.
Examples of the conductive compound include ion conductive resins and ion conductive agents.
The foamed elastic layer may contain either an ion conductive resin or an ion conductive agent, or both.
The foamed elastic layer may contain one type of ion-conductive resin alone or two or more types thereof.
In addition, the foamed elastic layer may contain one type of ion conductive agent alone or two or more types thereof.
When the foamed elastic layer contains an ion-conductive resin, it preferably further contains an elastic material other than the ion-conductive resin from the viewpoint of adjustment of conductivity and durability.
Further, when the foamed elastic layer contains an ionic conductive agent, it is preferable that it further contains an elastic material or an ionic conductive resin other than an ionic conductive resin from the viewpoint of conductivity and durability. More preferably, it further comprises materials.
The ion-conductive resin is not particularly limited, and known ion-conductive resins are used, but from the viewpoint of resistance maintenance, it preferably contains epichlorohydrin rubber.

From the viewpoint of resistance maintenance, conductivity and durability, the content of the ion-conductive resin should be the same as the ion-conductive resin contained in the foamed elastic layer and the elastic material other than the ion-conductive resin (also referred to as the "resin component"). ) is preferably 20 parts by mass or more, more preferably 50 parts by mass or more, and particularly preferably 90 parts by mass or more and 100 parts by mass or less.

The ionic conductive agent is not particularly limited, and known ionic conductive agents are used.
Examples of ion conducting agents include quaternary ammonium salts (e.g., lauryltrimethylammonium, stearyltrimethylammonium, octadodecyltrimethylammonium, dodecyltrimethylammonium, hexadecyltrimethylammonium, perchlorates such as modified fatty acids and dimethylethylammonium). , chlorates, hydroborofluorates, sulfates, ethosulfate salts, benzyl halide salts (e.g., benzyl bromide salts, benzyl chloride salts, etc.), aliphatic sulfonates, higher alcohol sulfates, Higher alcohol ethylene oxide added sulfate, higher alcohol phosphate, higher alcohol ethylene oxide added phosphate, various betaines, higher alcohol ethylene oxide, polyethylene glycol fatty acid ester, polyhydric alcohol fatty acid ester, various ionic liquids and fluorine-based charged inhibitors and the like.
Among these, quaternary ammonium salts are preferred from the viewpoint of resistance maintenance.

Among them, the anion possessed by the ion conductive agent is preferably an anion having at least one structure selected from the group consisting of a chlorine atom, an alkoxide group, and a sulfonate group, from the viewpoint of resistance maintenance. It is more preferably an anion having at least one structure selected from the group consisting of an atom and an alkoxide group, more preferably an anion having a chlorine atom, and particularly preferably a perchlorate ion. .

The content of the ion conductive agent should be 0.01 parts by mass or more and 10 parts by mass or less with respect to the total content of the resin components contained in the foamed elastic layer, from the viewpoint of resistance maintenance, conductivity, and durability. is preferred, and more preferably 0.1 parts by mass or more and 3 parts by mass or less.

-Carbon black-
The foamed elastic layer may contain carbon black.
Carbon black includes, for example, carbon black produced by a contact method (e.g. channel black, roll black, disk black, etc.), carbon black produced by a furnace method (e.g. gas furnace black, oil furnace black, etc.). , and carbon black produced by a thermal method (for example, thermal black, acetylene black, etc.).
Among them, from the viewpoint of conductivity and resistance stability, at least one carbon black selected from the group consisting of ketjen black, oil furnace black, channel black, acetylene black and thermal black is preferable, consisting of acetylene black and thermal black. At least one carbon black selected from the group is more preferable.
Carbon black may be used alone or in combination of two or more.

As the carbon black, it is preferable to use two or more kinds of carbon black having different oil absorption properties in combination from the viewpoint of reducing variation in resistance. Specifically, it is preferable to use at least one of ketjen black and acetylene black, which have high oil absorption and excellent electrical conductivity, together with thermal black, which has low oil absorption and excellent rubber reinforcing properties. Combined use of these carbon blacks reduces the resistance variation of the belt. The carbon black with different oil absorption means carbon black with different DBP (dibutyl phthalate) oil absorption. The DBP oil absorption is a value defined in ASTM D2414-6TT.
Here, the ratio of carbon black to be used is, for example, preferably at least one of ketjen black and acetylene black: thermal black = 1:1 to 1:8, more preferably 1:2 to 1:5 in mass ratio. .

Further, from the viewpoint of resistance stability, in the foamed elastic layer, among the two or more kinds of carbon blacks with different oil absorption, the content of the carbon black with the lowest oil absorption is higher than the content of the other carbon blacks. is preferably large.

From the viewpoint of low resistance and resistance stability, the content of carbon black is preferably 1% by mass or more and 60% by mass or less, and 5% by mass or more and 50% by mass or less, relative to the total mass of the elastic layer. is more preferable, and more preferably 10% by mass or more and 45% by mass or less.

-Vulcanizing agent-
The foamed elastic layer may contain foamed and vulcanized rubber.
Examples of vulcanizing agents for vulcanizing rubber include sulfur, organic sulfur-containing compounds, and organic peroxides. Examples of organic sulfur-containing compounds include tetramethylthiuram disulfide and N,N'-dithiobismorpholine. Examples of organic peroxides include dicumyl peroxide and benzoyl peroxide.
A vulcanizing agent may be used individually by 1 type, or may use 2 or more types together.
The amount of the vulcanizing agent to be added can be appropriately adjusted depending on the characteristics of the resin to be used and the application of the foamed elastic member. It is preferably 1 part by mass or less, and more preferably 1 part by mass or more and 8 parts by mass or less.

The foamed elastic layer may contain foamed and peroxide-vulcanized rubber.
In the present embodiment, cross-linking with peroxide is also referred to as peroxide vulcanization, although sulfur atoms are not used.
Peroxide vulcanization in making foamed resins is preferably carried out using peroxides.
The peroxide may be an inorganic peroxide or an organic peroxide, but an organic peroxide is preferred.
Examples of organic peroxides include diisopropylbenzene hydroperoxide, 2,4-dichlorobenzoyl peroxide, benzoyl peroxide, t-butyl perbenzoate, cumyl hydroperoxide, t-butyl hydroperoxide, 1,1 -di(t-butylperoxy)-3,3,5-trimethylhexane, n-butyl-4,4-di(t-butylperoxy)valerate, α,α'-bis(t-butylperoxyisopropyl) ) benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, t-butylperoxycumene and the like.

A peroxide may be used individually by 1 type, or may use 2 or more types together.
The amount of the peroxide to be used can be appropriately adjusted depending on the properties of the resin to be used and the application of the foamed elastic member. and more preferably 0.5 parts by mass or more and 10 parts by mass or less.

-Vulcanization accelerator-
A vulcanization accelerator may be used to form the foamed elastic layer.
As the vulcanization accelerator, various conventionally used vulcanization accelerators are used, and it is particularly preferable to use a sulfenamide-based vulcanization accelerator. The amount of the vulcanization accelerator added is preferably 0.3 parts by mass or more and 4 parts by mass or less, and more preferably 0.5 parts by mass or more and 3 parts by mass or less with respect to 100 parts by mass of the resin component of the elastic layer. more preferred.

-Blowing agent-
A foaming agent is preferably used to form the foamed elastic layer.
As the foaming agent, a known one can be used, and it may be a chemical foaming agent or a physical foaming agent, but the chemical foaming agent is preferable from the viewpoint of handling and storage.
The chemical foaming agent may be an inorganic compound or an organic compound, and two or more of them may be used in combination. Two or more agents are preferably used in combination, more preferably two or three agents in combination, and particularly preferably two agents in combination.
Examples of organic chemical foaming agents include nitrosamine compounds such as dinitrosopentamethylenetetramine (DPT), azo compounds such as azodicarbonamide (ADCA), 4,4′-oxybisbenzenesulfonyl hydrazide (OBSH) and hydrazodicarbonate. Hydrazine compounds such as amide (HDCA) and the like are included.
Examples of inorganic chemical foaming agents include hydrogen carbonates such as sodium bicarbonate, carbonates, and combinations of hydrogen carbonates and organic acid salts.
Among them, organic chemical blowing agents are preferred, and nitrosamine compounds, azo compounds and hydrazine compounds are more preferred, azodicarbonamide (ADCA), 4,4'-oxybis(benzenesulfonylhydrazide) (OBSH), and dinitrosopentamethylenetetramine. At least one compound selected from the group consisting of (DTP) is more preferred, and it is particularly preferred to use two of azodicarbonamide (ADCA) and 4,4'-oxybis(benzenesulfonylhydrazide) (OBSH) in combination. .

Examples of physical blowing agents include inert gases such as nitrogen and carbon dioxide, and volatile organic compounds. Among them, it is preferable to use an inert gas, and it is preferable to use supercritical carbon dioxide, nitrogen, or a mixture thereof.

When a chemical foaming agent is used, it is preferably mixed with a composition containing an elastic material and foamed by heat.
When a physical foaming agent is used, it may be mixed with a composition containing an elastic material and foamed at normal pressure or under pressure, or the composition may be impregnated with the physical foaming agent and foamed. .
The foaming method is not particularly limited, but specific examples include a batch foaming method, a press foaming method, a normal pressure foaming method, a normal pressure secondary foaming method, and steam pressure heating foaming in a vulcanization pot. mentioned.
As for the foaming agent and foaming method, reference can be made to the foaming agent and foaming method described in Japanese Patent Laid-Open No. 11-106543, "New Edition: Basics of Rubber Technology, Revised Edition", edited by the Japan Rubber Association.
Further, the foamed elastic layer is preferably a semi-open foam or open foam (also referred to as "semi-open cell" and "open cell", respectively).

The foaming agents may be used singly or in combination of two or more, or a chemical foaming agent and a physical foaming agent may be used in combination.
The amount of the foaming agent used can be appropriately adjusted depending on the characteristics of the resin to be used and the application of the foamed elastic member. 0.5 to 20 parts by mass, more preferably 1 to 15 parts by mass, and particularly preferably 2 to 10 parts by mass. Within the above range, the resistance stability is more excellent.

Further, when two or more chemical foaming agents are used, the mass ratio (F1/F2) between the amount F1 of the foaming agent having the lowest decomposition temperature and the amount F2 of the foaming agent having the highest decomposition temperature is the ability to suppress distortion over time. and, from the viewpoint of the stability of the outer diameter over time, it is preferably 0.2 or more and 5.0 or less, and more preferably 0.25 or more and 4.0 or less.

-Other additives-
The foamed elastic layer may contain other additives.
Other additives include various known rubber additives. Specifically, for example, processing aids (stearic acid, etc.), foaming aids, softeners, plasticizers, curing agents, antioxidants, surfactants, coupling agents, fillers (silica, calcium carbonate, etc.) etc.

-Outer diameter variation-
When the foamed elastic member had a roller shape, the initial outer diameter of the foamed elastic member was set to Da, and after being left in an environment of 60°C and 85% RH for 48 hours, it was left in an environment of 22°C and 55% RH for 24 hours. When the outer diameter Db of the later foamed elastic member is taken, the value of Da - Db (the amount of change in the outer diameter) is preferably less than 531 μm from the viewpoint of the suppression of distortion over time and the stability of the outer diameter over time. , is more preferably less than 521 μm, even more preferably less than 450 μm, particularly preferably less than 15 μm.

The value of Da-Db is measured as follows.
The outer diameter of the roll left still for 24 hours or longer in a 22° C., 55% environment is measured at 20 mm at both ends and at three points in the center. An outer diameter Da is obtained by averaging the outer diameters at these three locations.
Thereafter, the foamed elastic layer is allowed to stand in an environment of 60° C. and 85% RH for 48 hours without touching anything.
After standing still for 48 hours, the outer diameter of the roll which was left standing again in a 22° C., 55% environment for 24 hours was similarly measured at 20 mm at both ends and at three points in the center, and the average outer diameter was defined as outer diameter Db.
Da-Db is calculated and used as the outer diameter change amount.

- Amount of compression set -
The foamed elastic layer was left in an environment of 60° C. and 85% RH for 48 hours in a state in which the foamed elastic layer was cut into an SUS metal flat plate with a thickness of 8.0 mm by 0.6 mm, and then in an environment of 22° C. and 55% RH for 24 hours. After standing, the flat metal plate was removed, and the strain amount (compression permanent strain amount) of the outer diameter of the foamed elastic member at the portion where the flat metal plate was bitten was measured 30 minutes later. From the viewpoint of outer diameter stability, it is preferably less than 225 μm, more preferably 220 μm or less, still more preferably 210 μm or less, and particularly preferably 170 μm or less.

The compression set amount is measured as follows.
The foamed elastic layer was allowed to stand in an environment of 22°C and 55% for 24 hours or more, and then set so that the foamed elastic layer was inserted into a SUS metal flat plate with a thickness of 8.0mm facing each other by 0.6mm. , under 85% RH environment for 48 hours.
After standing for 48 hours, it was again allowed to stand in a 22° C., 55% environment for 24 hours. The outer diameter of the roll may also be used.) is measured by a contact type shape measuring machine at three points, 20 mm from both ends of the portion of the foamed elastic member where the flat metal plate is bitten, and the central portion. The maximum value (Max value)-minimum value (Min value) of the outer diameter at each of these three points is calculated, and the Max value-Min value of the three points is averaged to determine the amount of compression set.

The thickness of the foamed elastic layer is not particularly limited, and may be appropriately selected according to the application. For example, when the foamed elastic member according to the present embodiment is used for the transfer roll, the thickness of the foamed elastic layer is preferably 2 mm or more and 20 mm or less, more preferably 2 mm or more and 15 mm or less.

The method of forming the foamed elastic layer is not particularly limited, but a method of vulcanizing and foaming a composition containing a resin component containing a conductive compound, a vulcanizing agent, and a foaming agent to form a foamed rubber layer. It is preferably mentioned.
Vulcanization and foaming in the step of obtaining the foamed resin may be performed simultaneously or sequentially. When it is performed sequentially, it is preferable to perform foaming after vulcanization.
Moreover, from the viewpoint of the ability to suppress distortion over time and the stability of the outer diameter over time, it is preferable to foam using two or more chemical foaming agents.
The temperature and time during vulcanization and foaming are not particularly limited, and may be appropriately set according to the vulcanizing and foaming agents to be used.
Vulcanization and foaming are preferably performed by heating, and the heating temperature is preferably 100° C. or higher and 200° C. or lower.
Alternatively, the vulcanization may be performed by microwave vulcanization.
Examples of the method for microwave vulcanization include the method described in JP-A-2008-176027.

The foamed elastic member according to this embodiment may further have other layers such as a surface layer, a rubber coating layer, an adhesive layer, etc., depending on the application.
Other layers are not particularly limited, and known layers are provided according to the application.

The foamed elastic member according to the present embodiment includes, for example, a charging roll for charging the surface of an image carrier in an electrophotographic copier, an electrostatic printer, etc., and a toner image formed on the image carrier onto a transfer medium. A transfer roll for transfer, a toner transport roll for transporting toner onto an image carrier, a conductive roll for supplying power or driving in combination with a conductive belt for electrostatically transporting paper, removing toner from the image carrier It is used as a cleaning roll for cleaning. It is also used as a power supply roll for charging an intermediate transfer member before ink is ejected from an inkjet head in an inkjet image forming apparatus.

<Image forming apparatus and process cartridge>
The image forming apparatus according to the present embodiment is an image forming apparatus including the elastic foam member according to the present embodiment, and is preferably an image forming apparatus including the elastic foam member according to the present embodiment as a transfer roll. charging means for charging the image carrier; latent image forming means for forming a latent image on the surface of the charged image carrier; and developing the latent image formed on the surface of the image carrier with toner. developing means for forming a toner image; and transfer means for transferring the toner image formed on the surface of the image carrier onto a recording medium, having the foamed elastic member according to the present embodiment as a transfer roll. More preferably, it is an image forming apparatus.

In the transfer means, for example, a configuration of a direct transfer system to a recording medium having a transfer roll alone, or an intermediate transfer member to which the toner image formed on the surface of the image carrier is transferred and the surface of the image carrier. A configuration of an intermediate transfer system including a primary transfer roll for transferring a formed toner image onto the surface of an intermediate transfer member and a secondary transfer roll for transferring the toner image transferred on the surface of the intermediate transfer member onto a recording medium is mentioned. be done.
In the configuration of the direct transfer system, it is preferable to include the transfer roll according to the present embodiment as the transfer roll arranged to face the image carrier.
Further, in the configuration of the intermediate transfer system, it is preferable to include the transfer roll according to the present embodiment as at least one of the primary transfer roll and the secondary transfer roll.
Further, the conductive roll according to the present embodiment may be used as a power supply or drive roll within the paper transport belt.

As an image forming apparatus according to the present embodiment, for example, a normal mono-color image forming apparatus in which only a single color toner is accommodated in a developing device, and a toner image held on an image carrier are directly transferred onto a recording medium. An image forming apparatus, a color image forming apparatus that sequentially repeats primary transfer of a toner image held on an image carrier onto an intermediate transfer member, and a plurality of image carriers each having a developing device for each color arranged in series on the intermediate transfer member. any of the tandem type color image forming apparatus arranged in a row.

A process cartridge according to the present embodiment is a process cartridge that has the elastic foam member according to the present embodiment and is detachable from an image forming apparatus, and is a process cartridge that has the elastic foam member according to the present embodiment as a transfer roll. A process cartridge which preferably has the foamed elastic member according to the present embodiment as a transfer roll, has transfer means for transferring a toner image formed on the surface of an image carrier to a recording medium, and is detachable from an image forming apparatus. is more preferable.
Further, the process cartridge according to the present embodiment includes 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, and image holding means, as required. At least one means selected from developing means for developing a latent image formed on the surface of the body with toner to form a toner image may be provided.

An image forming apparatus according to the present embodiment will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present embodiment. The image forming apparatus is an image forming apparatus in which the elastic foam member according to the present embodiment is applied to a primary transfer roll and a secondary transfer roll. It is a device.

The image forming apparatus shown in FIG. 1 is a first to electrophotographic system for outputting 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 arranged side by side with a specific distance from each other in the horizontal direction. Note that these units 10Y, 10M, 10C, and 10K may be process cartridges that are removable from the main body of the image forming apparatus.

Above each unit 10Y, 10M, 10C, and 10K in the drawing, an intermediate transfer belt 20 as an intermediate transfer member is arranged through each unit. The intermediate transfer belt 20 is wound while tension is applied to a drive roll 22 and a support roll 24 in contact with the inner surface of the intermediate transfer belt 20, which are spaced apart from each other in the left-to-right direction in FIG. A transfer unit for the image forming apparatus is configured so as to travel in the direction toward the fourth unit 10K.
The support roll 24 is urged in a direction away from the drive roll 22 by a spring (not shown) or the like, and a specific tension is applied to the intermediate transfer belt 20 wound around both. An intermediate transfer member cleaning device 30 is provided on the intermediate transfer belt 20 on the side of the image carrier so as to face the drive roll 22 .
Further, the developing devices (developing means) 4Y, 4M, 4C and 4K of the respective units 10Y, 10M, 10C and 10K respectively store yellow, magenta, cyan and black toner cartridges 8Y, 8M, 8C and 8K. 4 colors of toner can be supplied.

Since the above-described first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, the first unit 10Y for forming a yellow image arranged on the upstream side in the running direction of the intermediate transfer belt is used here. will be described as a representative. By attaching reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y) to portions equivalent to those of the first unit 10Y, the second to fourth units Description of 10M, 10C, and 10K is omitted.

The first unit 10Y has a photoreceptor 1Y acting as an image carrier. Surrounding the photoreceptor 1Y are a charging roll 2Y that charges the surface of the photoreceptor 1Y to a specific potential, and the charged surface is exposed to a laser beam 3Y based on color-separated image signals to form an electrostatic charge image. An exposure device 3, a developing device (developing means) 4Y that supplies charged toner to the electrostatic charge image to develop the electrostatic charge image, and a primary transfer roll 5Y that transfers the developed toner image onto the intermediate transfer belt 20 (primary transfer roller 5Y). transfer means), and a photoreceptor cleaning device (cleaning means) 6Y for removing toner remaining on the surface of the photoreceptor 1Y after primary transfer with a cleaning blade.
The primary transfer roll 5Y is arranged inside the intermediate transfer belt 20 and provided at a position facing the photoreceptor 1Y. Further, a bias power source (not shown) that applies 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).

The operation of forming a yellow image in the first unit 10Y will be described below. First, prior to 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 stacking a photosensitive layer on a conductive base material (volume resistivity at 20° C.: 1×10 ⁶ Ωcm or less). This photosensitive layer normally has a high resistance (resistivity equivalent to that of general resin), but has the property of changing the specific resistance of the portion irradiated with the laser beam 3Y 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 according to yellow image data sent from a control unit (not shown). The laser beam 3Y irradiates the photosensitive layer on the surface of the photoreceptor 1Y, thereby forming an electrostatic charge image of a yellow print pattern on the surface of the photoreceptor 1Y.

The electrostatic charge image is an image formed on the surface of the photoreceptor 1Y by charging. The laser beam 3Y reduces the specific resistance of the irradiated portion of the photoreceptor layer, and the charged charges on the surface of the photoreceptor 1Y flow. On the other hand, it is a so-called negative latent image formed by charge remaining in the portion not irradiated with the laser beam 3Y.
The electrostatic charge image formed on the photoreceptor 1Y in this manner is rotated to a specific development position as the photoreceptor 1Y runs. 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 charge charged on the photoreceptor 1Y, and a developer roll (developer holding member). held on top. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner is electrostatically adhered to the static-eliminated 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 portion, a specific primary transfer bias is applied to the primary transfer roll 5Y, and the electrostatic force from the photoreceptor 1Y to the primary transfer roll 5Y is applied to the toner. Acting on the image, the toner image on the photoreceptor 1Y is transferred onto the intermediate transfer belt 20. FIG. 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 a control section (not shown) in the first unit 10Y, for example.
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.
In this way, the intermediate transfer belt 20 to 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 each color are superimposed and transferred in multiple layers.

The intermediate transfer belt 20 on which the four-color toner images are multiple-transferred through the first to fourth units is arranged on the intermediate transfer belt 20, the support roll 24 contacting the inner surface of the intermediate transfer belt 20, and the image holding surface side of the intermediate transfer belt 20. A secondary transfer portion is formed by a secondary transfer roll (secondary transfer means) 26 which is connected to the secondary transfer roller 26 . A cleaning blade made of an elastic material is in contact with the outer peripheral surface of the secondary transfer roll 26 , and adheres to the outer peripheral surface of the secondary transfer roll 26 without being transferred from the intermediate transfer belt 20 onto the recording medium P. toner is removed.

On the other hand, the recording medium P is fed to the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 via the supply mechanism at a specific timing, and a specific secondary transfer bias is applied to the support roll 24. . The transfer bias applied at this time has the same (-) polarity as the polarity (-) of the toner. is transferred onto the recording medium P. The secondary transfer bias at this time is determined according to the resistance detected by resistance detection means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

After that, the recording medium P is sent to a fixing device (fixing means) 28, where the toner image is heated, and the superimposed toner images are melted and fixed onto the recording medium P. FIG. The recording medium P on which the fixing of the color image has been completed is carried out toward the discharge section, and a series of color image forming operations is completed.

Note that the image forming apparatus exemplified above has a configuration in which the toner image is transferred onto the recording medium P via the intermediate transfer belt 20, but the image forming apparatus according to the present embodiment is limited to the above configuration. Instead, a structure in which a toner image is directly transferred onto the recording medium P from the photosensitive member may be used.

Examples will be described below, but the present invention is not limited to these examples. In the following description, "parts" and "%" are all based on mass unless otherwise specified.

(Examples 1 to 7, and Comparative Examples 1 and 2)
<Production of conductive roll>
-Formation of foamed elastic layer-
The blending mass parts of foaming agent A and foaming agent B were appropriately adjusted so that the X/Y ratio of the following mixture was a desired value, and after kneading with an open roll to obtain rubber kneaded material A, a hole was formed in the center. It was extruded in an open state (doughnut shape) and formed into a cylindrical roll.
Then, the cylindrical roll was heated at 160° C. for 30 minutes to vulcanize and foam. After that, annealing treatment was performed at 120° C. for 2 hours.
An example of an outer diameter of 18 mm (rubber thickness of 5.0 mm) and a length of 224 mm by inserting a SUS (stainless steel) shaft with a diameter of 8 mm into the hole in the center of the roll after annealing, and polishing the outer peripheral surface of the roll. The conductive rolls of Examples 1 to 10 and Comparative Examples 1 and 2 were obtained. The polished roll was washed with an ultrasonic cleaner containing 1 μS/cm pure water (20° C.) for 40 minutes, taken out of water, and dried naturally.
・Rubber material (mixture of 60% epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber (CG102, manufactured by Osaka Soda Co., Ltd.) and 40% nitrile acrylobutadiene rubber (N230SV, manufactured by JSR Corporation)): 100 Parts by mass Carbon black (#55, manufactured by Asahi Carbon Co., Ltd.): 15 parts by mass Vulcanizing agent (sulfur) (200 mesh, manufactured by Tsurumi Chemical Industry Co., Ltd.): 1 part by mass Vulcanization accelerator (Noccellar DM, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.): 1.5 parts by mass Vulcanization accelerator (Nocceler TET, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.): 1.0 parts by mass Zinc oxide (zinc white 1 No.: Seido Chemical Industry Co., Ltd.): 5 parts by mass Calcium carbonate (Whiten SSB: manufactured by Shiraishi Calcium Co., Ltd.): 10 parts by mass Stearic acid (stearic acid S: manufactured by Kao Corporation): 1 Part by mass Foaming agent A azodicarbonamide (ADCA): appropriate amount Foaming agent B 4,4'-oxybis (benzenesulfonyl hydrazide, OBSH): appropriate amount Foaming aid urea compound: 0.5 parts by mass

(Example 8)
A conductive roll was obtained in the same manner as in Example 1, except that the epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer rubber of Example 1 was changed to EPION301 (manufactured by Osaka Soda Co., Ltd.).

(Example 9)
A conductive roll was obtained in the same manner as in Example 1, except that 1 part by mass of a quaternary ammonium salt (lauryltrimethylammonium) was added to the mixture of Example 1.

(Example 10)
A conductive roll was obtained in the same manner as in Example 1, except that the outer peripheral surface of Example 1 was polished to change the outer diameter by 14 mm (rubber thickness: 3.0 mm).

<Measurement of X/Y ratio>
Using a razor, cross-sections in a direction perpendicular to the surface direction of the foamed elastic layer were prepared at four 90° positions on the central portion of the foamed rubber roll.
The cross-sectional shape was observed using a laser microscope VK-X200 manufactured by Keyence Corporation to obtain a cross-sectional image of foaming. At this time, observation with a laser microscope was performed at a magnification at which a foamed shape was obtained.
The resulting image was introduced into Image-Pro Plus, an image analysis software manufactured by Media Cybernetics, and the aspect ratio (X/Y ratio) of foamed rubber cells (foam structure) was measured and measured for 100 or more cells. was calculated and the average value was calculated.

<Residual ion evaluation method for conductive roll>
A method for measuring the amount of liberated chlorine ions in the foamed elastic layer is as follows.
A 0.5 g sample is collected from the foamed elastic layer. A 0.5 g sample is put into a resin container, 100 mL of ultrapure water (0.058 μS/cm) is added to the resin container, and the sample is immersed for 30 minutes to extract ion components. The extract was diluted 50-fold and injected into ion chromatography (ICS-2100 manufactured by Thermo Fisher Scientific) to measure chloride ions. AS-19 (manufactured by Thermo Fisher Scientific) was used as the column, potassium hydroxide was used as the eluent, and the solution was fed at a flow rate of 1.0 mL/min. Then, using an electrical conductivity detector, chloride ions are quantified by an absolute calibration curve method using a mixed standard solution containing chloride ions (manufactured by Kanto Chemical Co., Ltd., anion mixed standard solution I), and the amount of chloride ions is determined. asked.
This operation was performed on three types of samples taken from both ends and the central portion of the foamed elastic layer in the thickness direction of the foamed elastic member, and the amount of chloride ions was determined, and the average value was taken as the liberated amount of chloride ions.

<Evaluation of change in outer diameter>
The outer diameter of the roll left still for 24 hours or longer in a 22° C., 55% environment is measured at 20 mm at both ends and at three points in the center. An outer diameter Da was obtained by averaging the outer diameters at these three locations.
Thereafter, the foamed elastic layer was allowed to stand in an environment of 60° C. and 85% RH for 48 hours without touching anything.
After standing still for 48 hours, the outer diameter of the roll was again allowed to stand in a 22° C., 55% environment for 24 hours.
Da-Db was calculated and used as the amount of change in outer diameter.

<Evaluation of compression set amount>
The roll was allowed to stand in an environment of 22°C and 55% for 24 hours or longer, and was set to 0.6 mm into a SUS metal flat plate with a thickness of 8.0 mm facing the foamed elastic layer. C. and 85% RH environment for 48 hours.
After standing still for 48 hours, it was again allowed to stand in a 22° C., 55% environment for 24 hours. Measurements were taken at three points, 20 mm from both ends of the biting portion and the central portion. The maximum value (Max value)-minimum value (Min value) of the outer diameter at each of these three points was calculated, and the Max value-Min value at the three points was averaged to obtain the compression set amount.

The evaluation results are summarized in Table 1.

*1: The amount of foaming agent A and foaming agent B used in Examples 2 to 5 and 7 in Table 1 was adjusted appropriately between the amount used in Example 1 and the amount used in Example 6. Each foamed elastic member was produced so as to have X/Y, etc. described in 1 above.
*2: The amount of blowing agent A and blowing agent B used in Comparative Example 1 in Table 1 was slightly less than the amount of blowing agent A used in Example 1, and the amount of blowing agent B used in Example 1. A foamed elastic member was produced so as to have X/Y, etc. shown in Table 1 with a slightly larger ratio than the above.
*3: The amount of blowing agent A and blowing agent B used in Comparative Example 2 in Table 1 was slightly larger than the amount of blowing agent A used in Example 6, and the amount of blowing agent B used in Example 6. A foamed elastic member was produced so as to have X/Y, etc. shown in Table 1 with a slightly smaller ratio.

As shown in Table 1, the foamed elastic members of Examples had a smaller compression set than the foamed elastic members of Comparative Examples even after long-term storage in a high-temperature, high-humidity environment.
In addition, as shown in Table 1, the foamed elastic members of Examples showed little change in outer diameter even after long-term storage in a high-temperature, high-humidity environment.

1Y, 1M, 1C, 1K photoreceptors (examples of image carriers)
2Y, 2M, 2C, 2K charging roll (an example of charging means)
3 Exposure device (an example of electrostatic charge image forming means)
3Y, 3M, 3C, 3K laser beams 4Y, 4M, 4C, 4K developing device (an example of developing means)
5Y, 5M, 5C, 5K primary transfer roll (an example of primary transfer means)
6Y, 6M, 6C, 6K photoreceptor cleaning device (an example of cleaning means)
8Y, 8M, 8C, 8K toner cartridges 10Y, 10M, 10C, 10K image forming unit 20 intermediate transfer belt (an example of an intermediate transfer body)
22 drive roll 24 support roll 26 secondary transfer roll (an example of secondary transfer means)
30 Intermediate transfer member cleaning device P Recording paper (an example of recording medium)

Claims (7)

a conductive substrate;
a foamed elastic layer disposed on the conductive substrate;
The foamed elastic layer contains epichlorohydrin rubber, and the liberation amount of chlorine ions is 1 μg/g or more and 80 μg/g or less,
In the cross section of the foamed elastic layer cut in the thickness direction of the foamed elastic layer, the thickness direction of the foamed elastic layer is the y-axis, and the direction perpendicular to the y-axis in the cross section is the x-axis. The average value of X/Y is 0.86 or more and 1.16 or less, where X is the maximum length of the cells in the x-axis direction and Y is the maximum length of the y-axis direction of the cells in the elastic layer. Element. The elastic foam member according to claim 1 , wherein the elastic foam member is roller-shaped. The initial outer diameter of the foamed elastic member was defined as Da, and the outer diameter of the foamed elastic member after being left in an environment of 60°C and 85% RH for 48 hours and then in an environment of 22°C and 55% RH for 24 hours was defined as Db. 3. The foamed elastic member according to claim 2 , wherein the value of Da-Db is less than 521 μm. The foamed elastic layer was left in a 60° C. 85% RH environment for 48 hours in a state in which the foamed elastic layer was cut into a metal flat plate with a thickness of 8.0 mm by 0.6 mm, and then left in a 22° C. 55% RH environment for 24 hours. 4. The deformation amount of the outer diameter of the foamed elastic member at the portion where the metal flat plate is bitten, measured 30 minutes after the metal flat plate is removed, is less than 225 μm. The foamed elastic member according to 1. A transfer device comprising the foamed elastic member according to any one of claims 1 to 4 as a transfer member for transferring a transfer material to a transferred material. A transfer device according to claim 5 ,
A process cartridge that is attached to and detached from an image forming apparatus. an image carrier;
a charging device that charges the surface of the image carrier;
an electrostatic latent image forming device that forms an electrostatic latent image on the surface of the charged image carrier;
a developing device that develops an electrostatic latent image formed on the surface of the image carrier with a developer containing toner to form a toner image;
6. The transfer device according to claim 5 , which transfers the toner image onto the surface of a recording medium;
An image forming apparatus.

Images