JP6883202B2 - Conductive foam member and its manufacturing method, transfer roll, process cartridge, and image forming apparatus - Google Patents

Description

The present invention relates to a conductive foam member and a method for producing the same, a transfer roll, a process cartridge, and an image forming apparatus.

Conductive rubber rollers such as charging rollers, transfer rollers, and developing rollers are used in many electrophotographic image forming devices (also referred to as electrophotographic devices and electrophotographic image forming devices) such as copiers and printers. These rubber rollers are required to maintain a uniform nip width by contacting with a photoconductor in order to respond to high speed and high image quality of the device, and when the rubber layer is a foam, the foam It is desired that the foam cells are dense and uniform.

For example, Patent Document 1 describes a method for manufacturing a conductive rubber roller having a foam rubber layer on a conductive core material, wherein the rubber material of the foam rubber layer is acrylonitrile butadiene rubber, epichlorohydrin rubber and ethylene as rubber components. It contains at least one selected from the oxide-propylene oxide-allyl glycidyl ether ternary copolymer, and the amount of chlorine in the rubber component is 21% by mass or less with respect to 100 parts by mass of the rubber component, for foam formation. The only foaming agent to be arranged in is p, p'-oxybis (benzenesulfonyl hydrazide), the urea-based foaming aid is not arranged, and the vulcanized foaming of the rubber material is performed by microwave irradiation and heated air. A method for manufacturing a conductive rubber roller, which is characterized by being performed, is disclosed.

Further, Patent Document 2 describes a conductive rubber roller having a rubber layer on a conductive shaft body, wherein the rubber component of the rubber layer has an ethylene oxide content of 50 mol% or more and 60 mol% or less and an allylglycidyl ether content. It contains epichlorohydrin rubber having a content of 2 mol% or more and 10 mol% or less and acrylonitrile butadiene rubber having an acrylonitrile content of 16% by mass or more and 20% by mass or less. It is 25 parts by mass or more and 40 parts by mass or less, the rubber layer is crosslinked with sulfur and / or a sulfur donor, and the rubber layer is chemically foamed, and the hardness is 15 ascar C hardness. A conductive rubber roller characterized by having a degree of 40 degrees or more is disclosed.

Japanese Unexamined Patent Publication No. 2008-216449 Japanese Unexamined Patent Publication No. 2008-216462

The problems to be solved by the present invention are ozone resistance and ozone resistance as compared with the case where nitrile rubber, epichlorohydrin-based rubber, and ethylene-propylene-diene rubber are sulfur-vulcanized and foamed to contain a foamed resin. It is an object of the present invention to provide a conductive foamed member having excellent resistance stability and small permanent strain.

Specific means for solving the above problems include the following aspects.
< 1 > is
At least one resin A selected from the group consisting of nitrile rubber, chloroprene rubber and hydride nitrile rubber, and at least one resin B selected from the group consisting of styrene-butadiene rubber and epichlorohydrin-based rubber. It is a conductive foamed member containing a foamed resin obtained by cross-linking and foaming ethylene-propylene-diene rubber with ethylene-propylene-diene rubber, and carbon black.

< 2 > is
The conductive foaming member according to < 1 > , wherein the resin B contains an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer.

< 3 > is
The conductive foamed member according to < 1 > or < 2 > , wherein the content of the resin B in the foamed resin is 30% by mass or less with respect to the total mass of the foamed resin.

< 4 > is
It said carbon black is a conductive foamed member according to any one of <1> to <3> comprising two or more carbon blacks having different oil absorbing.

< 5 > is
The resin B is a conductive foamed member according to any one of <1> to <4> comprising a styrene-butadiene rubber.

< 6 > is
A conductive foamed member according to any one of <1> to <5> to selected further comprising at least one compound of zinc oxide and the group consisting of magnesium oxide.

< 7 > is
Wherein the resin A is a conductive foamed member according to any one of the at least one resin selected from the group consisting of chloroprene rubber and hydrogenated nitrile rubber <1> to <6>.

< 8 > is
At least one resin A selected from the group consisting of nitrile rubber, chloroprene rubber and hydride nitrile rubber, and at least one resin B selected from the group consisting of styrene-butadiene rubber and epichlorohydrin-based rubber. ethylene - propylene - diene rubber and a carbon black, a peroxide, according to any one of <1> to <7> of the composition by crosslinking and foaming including including the step of obtaining a foamed resin and a blowing agent This is a method for manufacturing a conductive foam member.

< 9 > is
A transfer roller having a conductive foamed member according to any one of <1> to <7>.

< 10 > is
It is a process cartridge having the transfer roll according to < 9 > , including a transfer means for transferring a toner image formed on the surface of an image holder to a recording medium, and is attached to and detached from an image forming apparatus.

< 11 > is
Toner is an image holder, a charging means for charging the image holder, a latent image forming means for forming a latent image on the surface of the charged image holder, and a latent image formed on the surface of the image holder. An image including a developing means for forming a toner image by developing the toner image, and a transfer means having the transfer roll according to < 9 > and transferring the toner image formed on the surface of the image holder to a recording medium. It is a forming device.

According to < 1 > , ozone resistance and resistance stability are compared with the case where nitrile rubber, epichlorohydrin-based rubber, and ethylene-propylene-diene rubber are sulfur-vulcanized and foamed to contain a foamed resin. Provided is a conductive foamed member having excellent properties and low permanent strain.
According to < 2 > , a conductive foamed member having higher ozone resistance than when only styrene-butadiene rubber is used as the resin B is provided.
According to < 3 > , the conductive foamed member having more excellent resistance stability than the case where the content of the resin B in the foamed resin exceeds 30% by mass with respect to the total mass of the foamed resin is provided. Will be done.
According to < 4 > , a conductive foamed member having superior resistance stability is provided as compared with the case where the carbon black is only one type of carbon black.
According to < 5 > , a conductive foamed member having higher resistance stability than when only epichlorohydrin-based rubber is used as the resin B is provided.
According to < 6 > , a conductive foamed member having more excellent resistance stability as compared with the case where hydrotalcite is contained as an antacid is provided.
According to < 7 > , a conductive foamed member having superior ozone resistance and resistance stability as compared with the case where the resin A is a nitrile rubber is provided.
According to < 8 > , ozone resistance and resistance are stable as compared with the case of producing a foamed resin obtained by sulfur vulcanizing and foaming nitrile rubber, epichlorohydrin-based rubber, and ethylene-propylene-diene rubber. Provided is a method for producing a conductive foamed member having excellent properties and small permanent strain.
According to < 9 > , ozone resistance and resistance stability are compared with the case where nitrile rubber, epichlorohydrin-based rubber, and ethylene-propylene-diene rubber are sulfur-vulcanized and foamed to contain a foamed resin. A transfer roll having excellent performance and low permanent distortion is provided.
According to < 10 > , ozone resistance and resistance stability are compared with the case where nitrile rubber, epichlorohydrin-based rubber, and ethylene-propylene-diene rubber are sulfur-vulcanized and foamed to contain a foamed resin. A process cartridge having a transfer roll having excellent and low permanent strain is provided.
According to < 11 > , ozone resistance and resistance stability are compared with the case where nitrile rubber, epichlorohydrin-based rubber, and ethylene-propylene-diene rubber are sulfur-vulcanized and foamed to contain a foamed resin. An image forming apparatus having a transfer roll having excellent characteristics and small permanent distortion is provided.

It is a schematic block diagram which shows an example of the image forming apparatus which concerns on this embodiment.

Hereinafter, embodiments that are an example of the present invention will be described in detail.

<Conductive foam member>
The conductive foamed member according to the present embodiment is composed of at least one resin A selected from the group consisting of nitrile rubber, chloroprene rubber and hydride nitrile rubber, and the group consisting of styrene butadiene rubber and epichlorohydrin rubber. It contains a foamed resin obtained by cross-linking and foaming at least one selected resin B and ethylene-propylene-diene rubber, and carbon black.
Further, the conductive foaming member according to the present embodiment is intended for members in an image forming apparatus such as a toner supply member, a transfer member, a developing member, a charging member, a paper feed transport member, and a cleaning member, and for static electricity suppression, grounding, and the like. It is preferably used as a cushioning material, a sealing material, a dustproof material, and the like.
Among these, it is preferably used for a transfer member used in an image forming apparatus, and particularly preferably for a transfer roll.

Conventionally, a nitrile rubber (NBR) / epichlorohydrin-based material or a urethane-based foam material has been used for the conductive foam member. However, these materials have insufficient lifetime due to sufficient resistance stability due to ozone deterioration, hygroscopicity and hydrolyzability, and deterioration of strain due to a decrease in elasticity.
In addition, as a result of studies by the present inventors, ethylene-propylene-diene rubber, which is considered to have excellent ozone resistance, is mixed with nitrile rubber and epichlorohydrin-based rubber, and vulcanization with sulfur (sulfur vulcanization) is performed. The foamed resin used did not have sufficient resistance stability and ozone resistance.
On the other hand, the conductive foamed member according to the present embodiment has excellent ozone resistance and resistance stability due to the above configuration, and has a small permanent strain. The reason is not clear, but it is presumed as shown below.

At least one resin A selected from the group consisting of nitrile rubber, chloroprene rubber and vulcanized nitrile rubber, and at least one resin B selected from the group consisting of styrene-butadiene rubber and epichlorohydrin-based rubber. By using ethylene-propylene-diene rubber, the compatibility of the resins with each other is excellent, the permanent strain of the obtained foamed resin is reduced, and by containing carbon black, sufficient conductivity is ensured. By cross-linking and foaming the seed resin to form a foamed resin with excellent compatibility, the reaction uniformity and its vulcanization rate are improved, and ozone deterioration, moisture absorption, hydrolysis, etc. over time are suppressed. It is estimated that a conductive foamed member having excellent ozone resistance and resistance stability can be obtained.

Hereinafter, the details of the conductive foamed member according to the present embodiment will be described.

(Resin A)
The foamed resin in the conductive foamed member according to the present embodiment contains at least one resin A selected from the group consisting of nitrile rubber, chloroprene rubber and hydrogenated nitrile rubber.
The resin A is preferably at least one selected from the group consisting of chloroprene rubber and hydrogenated nitrile rubber from the viewpoint of resistance stability and suppression of permanent strain.
The nitrile rubber is a copolymer of acrylonitrile and butadiene (acrylonitrile butadiene rubber), and may be a copolymer further copolymerized with a monomer other than acrylonitrile and butadiene.
Examples of monomers other than acrylonitrile and butadiene include methacrylic acid, isoprene, and vinyl chloride.
Further, from the viewpoint of resistance stability and suppression of permanent strain, the content of the monomer unit (acrylonitrile content) formed by polymerizing acrylonitrile in the nitrile rubber is 10% by mass or more and 50% by mass with respect to the total mass of the nitrile rubber. It is preferably 25% by mass or more, more preferably 50% by mass or less, and further preferably 35% by mass or more and 50% by mass or less.
Further, the hydrogenated nitrile rubber having excellent ozone resistance instead of this may be any nitrile rubber to which a polar double bond is hydrogenated, and is preferably a hydrogenated body of the nitrile rubber. Further, in the above hydrogenation, it is not necessary to completely hydrogenate the ethylenically unsaturated bond, and a part of the ethylenically unsaturated bond may remain.
The chloroprene rubber is a polymer of chloroprene, and is preferably a homopolymer of chloroprene.

The resin A may be used alone or in combination of two or more.
The content of the resin A in the foamed resin is preferably 5% by mass or more and 50% by mass or less, preferably 15% by mass, based on the total resin components forming the foamed resin from the viewpoint of resistance stability and suppression of permanent strain. It is more preferably% or more and 45% by mass or less, further preferably 20% by mass or more and 40% by mass or less, and particularly preferably 25% by mass or more and 35% by mass or less. When it is 50% by mass or less, the uniformity of peroxide cross-linking is excellent.

(Resin B)
The foamed resin in the conductive foamed member according to the present embodiment contains at least one resin B selected from the group consisting of styrene-butadiene rubber and epichlorohydrin-based rubber.
The resin B preferably contains epichlorohydrin-based rubber from the viewpoint of ozone resistance, resistance stability and conductivity, and also has ozone resistance, compatibility and co-vulcanization (co-vulcanization). From the viewpoint of oxide crosslinkability), it is preferable to contain styrene-butadiene rubber.

Styrene-butadiene rubber is a copolymer rubber of styrene and butadiene.
The content of the monomer unit formed by polymerizing styrene in styrene-butadiene rubber (styrene content) is 60% by mass or more and 85% by mass or less with respect to the total mass of styrene-butadiene rubber from the viewpoint of ozone resistance and compatibility. It is preferably 60% by mass or more and 75% by mass or less.

The epichlorohydrin-based rubber is a polymer rubber containing at least epichlorohydrin as a polymerization component. The epichlorohydrin-based rubber may be either a homopolymer rubber of epichlorohydrin or a multi-polymer copolymer rubber (binary copolymer rubber, ternary copolymer rubber, etc.).

Examples of the epichlorohydrin-based rubber include epichlorohydrin homopolymer, epichlorohydrin-allyl glycidyl ether copolymer, and epichlorohydrin-alkylene oxide (ethylene oxide, propylene oxide, or both). Examples thereof include a polymer, an epichlorohydrin-alkylene oxide-allyl glycidyl ether copolymer, and an allyl glycidyl ether-modified epichlorohydrin-alkylene oxide copolymer.
Among them, epichlorohydrin-based rubbers include epichlorohydrin-allyl glycidyl ether copolymer and epichlorohydrin-alkylene from the viewpoints of co-vulcanization property, ozone resistance, resistance stability and conductivity. It is preferably at least one resin selected from the group consisting of oxide-allyl glycidyl ether copolymers, more preferably epichlorohydrin-alkylene oxide-allyl glycidyl ether copolymers, and epichlorohydrin. It is particularly preferable that it is a-ethylene oxide-allyl glycidyl ether copolymer.

The resin B may be used alone or in combination of two or more.
From the viewpoint of ozone resistance and resistance stability, the content of the resin B in the foamed resin is preferably 5% by mass or more and 50% by mass or less, preferably 20% by mass, based on the total resin components forming the foamed resin. It is more preferably% or more and 50% by mass or less, further preferably 20% by mass or more and 40% by mass or less, and particularly preferably 25% by mass or more and 35% by mass or less. When it is 50% by mass or less, sufficient characteristics can be obtained in terms of resistance adjustment, and it is inexpensive in terms of cost. On the other hand, when it is 5% by mass or more, the resistance of the foamed roll is appropriate and the resistance can be easily adjusted.

(Ethylene-propylene-diene rubber)
The foamed resin in the conductive foamed member according to the present embodiment contains ethylene-propylene-diene rubber.
Examples of the ethylene-propylene-diene rubber include copolymers of ethylene, propylene and diene (ethylidene norbornene, 1,4-hexadiene, dicyclopentadiene, isophorone structure, etc.).
The content (ethylene content) of the monomer unit formed by polymerizing ethylene in ethylene-propylene-diene rubber is preferably 40% by mass or more and 80% by mass or less, preferably 40% by mass or more and 70% by mass or more, from the viewpoint of ozone resistance. It is more preferably mass% or less.
Further, the content (propylene content) of the monomer unit formed by polymerizing propylene in ethylene-propylene-diene rubber is preferably 20% by mass or more and 60% by mass or less from the viewpoint of ozone resistance and low cost. More preferably, it is 30% by mass or more and 50% by mass or less.
Further, as the diene component in ethylene-propylene-diene rubber, ethylidene norbornene, 1,4-hexadiene, dicyclopentadiene and the like are preferably mentioned from the viewpoint of ozone resistance.

Ethylene-propylene-diene rubber may be used alone or in combination of two or more.
From the viewpoint of ozone resistance, the content of ethylene-propylene-diene rubber in the foamed resin is preferably 10% by mass or more and 60% by mass or less, preferably 20% by mass, based on the total resin components forming the foamed resin. It is more preferably 50% by mass or more, more preferably 20% by mass or more and 40% by mass or less, and particularly preferably 25% by mass or more and 35% by mass or less.

(Carbon black)
The conductive foamed member according to this embodiment contains carbon black.
Examples of carbon black include carbon black produced by the contact method (for example, channel black, roller black, disc black, etc.) and carbon black produced by the fur nest method (for example, gas fur nest black, oil fur nest black, etc.). , Carbon black produced by the thermal method (for example, thermal black, acetylene black, etc.) can be mentioned.
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, and it is composed of acetylene black and thermal black. At least one carbon black selected from the group is more preferred.
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 types of carbon black having different oil absorbency in combination from the viewpoint of reducing the 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 conductivity, and thermal black, which has low oil absorption and excellent rubber reinforcement. The combined use of these carbon blacks reduces the resistance variation of the belt. The carbon black having a different oil absorption property refers to a carbon black having a different DBP (dibutyl phthalate) oil absorption amount. The DBP oil absorption is a value defined in ASTM D2414-6TT.
Here, the ratio of carbon black used is, for example, preferably at least one of Ketjen black and acetylene black in terms of mass ratio: thermal black = 1: 1 to 1: 8, and more preferably 1: 2 to 1: 5. ..

The content of carbon black is preferably 1 part by mass or more and 50 parts by mass or less, and more preferably 15 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the foamed resin.

(Antacid)
From the viewpoint of resistance stability, the conductive foamed member according to the present embodiment preferably contains an acid-receiving agent, and more preferably contains the foamed resin containing epichlorohydrin-based rubber and an acid-receiving agent. ..
As the antacid, at least one compound selected from the group consisting of metal oxides and hydrotalcites is preferably mentioned.
Examples of the metal oxide include zinc oxide, magnesium oxide, lead oxide, calcium oxide, iron oxide, copper oxide, tin oxide, nickel oxide, titanium oxide, chromium oxide, cobalt oxide and aluminum oxide.
Furthermore, as the _{hydrotalcite, Mg 4.5 Al 2 (OH)} 13 CO 3 hydrate.
Among these, as the antacid, at least one compound selected from the group consisting of zinc oxide and magnesium oxide is particularly preferable from the viewpoint of resistance stability.

The antacid may be used alone or in combination of two or more.
From the viewpoint of resistance stability, the content of the antacid is preferably 0.1 part by mass or more and 30 parts by mass or less, and 0.5% by mass or more and 20% by mass or less with respect to 100 parts by mass of the foamed resin. It is more preferable that there is, and it is particularly preferable that it is 1% by mass or more and 10% by mass or less.

(Peroxide)
The foamed resin in the conductive foamed member according to the present embodiment is a foamed resin formed by peroxide cross-linking and foaming.
Peroxide cross-linking in the production of the foamed resin is preferably performed using a peroxide.
Further, in the present specification, peroxide cross-linking may be referred to as peroxide vulcanization. Needless to say, peroxide vulcanization is not sulfur vulcanization.
The peroxide may be an inorganic peroxide or an organic peroxide, but an organic peroxide is preferable.
Examples of the organic peroxide 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) ) Benzane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexin-3, t-butylperoxycumene and the like.

The peroxide may be used alone or in combination of two or more.
The amount of peroxide used can be appropriately adjusted depending on the characteristics of the resin used and the application of the foam, but is 0 with respect to 100 parts by mass of the total amount of resin A, resin B and ethylene-propylene-diene rubber used. It is preferably 1 part by mass to 20 parts by mass, and more preferably 0.5 part by mass to 10 parts by mass. Within the above range, ozone resistance and permanent strain suppression are excellent. Further, from the knowledge of the present inventor so far, it is preferable to blend styrene-butadiene rubber. It is presumed that the compounding of styrene-butadiene rubber improves the peroxide vulcanization rate, is an elastic material that is particularly effective for co-vulcanization in various mixed systems, and is an effective means of strain resistance. ..

(Foaming agent)
The foamed resin in the conductive foamed member according to the present embodiment is a foamed resin formed by peroxide cross-linking and foaming.
Foaming in the production of the foamed resin is preferably performed using a foaming agent.
As the foaming agent, a known one can be used, and it may be a chemical foaming agent or a physical foaming agent, but from the viewpoint of handleability and storage stability, the chemical foaming agent is preferable.
The chemical foaming agent may be an inorganic compound or an organic compound, and two or more kinds may be used in combination.
Examples of the organic chemical foaming agent include nitrosamine compounds such as dinitrosopentamethylenetetramine (DPT), azo compounds such as azodicarbonamide (ADCA), 4,4'-oxybisbenzenesulfonyl hydrazide (OBSH) and hydrazodicarbonate. Examples thereof include hydrazine compounds such as amide (HDCA).
Examples of the inorganic chemical foaming agent include hydrogen carbonates such as sodium bicarbonate, carbonates, and combinations of hydrogen carbonates and organic acid salts.
Among them, organic chemical foaming agents are preferable, nitrosamine compounds, azo compounds and hydrazine compounds are more preferable, and azodicarbonamide (ADCA), 4,4'-oxybis (benzenesulfonylhydrazide) (OBSH), and dinitrosopentamethylenetetramine. At least one compound selected from the group consisting of (DTP) is particularly preferred.

Examples of the physical foaming agent 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 carbon dioxide, nitrogen, or a mixture thereof in a supercritical state.

When a chemical foaming agent is used, it is preferable to mix it with a composition containing resin A, resin B and ethylene-propylene-diene rubber and foam it by heat.
When a physical foaming agent is used, it may be mixed with a composition containing resin A, resin B and ethylene-propylene-diene rubber and foamed under normal pressure or pressure, or the physical foaming agent may be added to the composition. May be impregnated and foamed.
The foaming method is not particularly limited, and specific examples thereof include a batch foaming method, a press foaming method, a normal pressure foaming method, and a normal pressure secondary foaming method.
Further, as the foaming agent and the foaming method, the foaming agent and the foaming method described in JP-A-11-106543, "New Edition Rubber Technology Basics Revised Edition", and edited by the Japan Rubber Association can be referred to.

As the foaming agent, one type may be used alone, two or more types may be used in combination, 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 used and the intended use of the foam, but it is 0. It is preferably 1 part by mass to 30 parts by mass, more preferably 0.5 part by mass to 20 parts by mass, further preferably 1 part by mass to 15 parts by mass, and 2 parts by mass to 10 parts by mass. Is particularly preferable. Within the above range, resistance stability and permanent strain suppression are excellent.

(Other additives)
The conductive foamed member according to the present embodiment may contain other additives.
Examples of other additives include various well-known additives for rubber. Specifically, for example, foaming aids, cross-linking accelerators (vulcanization accelerators), softeners, plasticizers, curing agents, antioxidants, surfactants, coupling agents, fillers (silica, calcium carbonate, etc.) ) Etc. can be mentioned.

The volume resistivity of the conductive foam member according to the present embodiment is preferably 10 ⁷ [Omega] cm or less, more preferably 10 ⁶ [Omega] cm or less, and preferably at 10 ⁴ [Omega] cm or more, more 10 ⁵ [Omega] cm More preferred.

The volume resistivity of the conductive foamed member according to the present embodiment is measured according to JIS K 6911 (1995) using a circular electrode (for example, a UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd.).
For the measurement of volume resistivity, the volume resistivity ρv (Ωcm) is calculated by the following formula. Here, in the following formula, t indicates the thickness of the conductive foamed member. Further, the voltage V (V) indicates the applied voltage, and the current I (A) indicates the current flowing when the voltage is applied.
Equation ρv = 2.011 × (V / I) × t
The volume resistivity is 22 ° C. using a circular electrode (UR probe of Hi-Lester IP manufactured by Mitsubishi Yuka Co., Ltd .: outer diameter Φ16 mm of columnar electrode part, inner diameter Φ30 mm, outer diameter Φ40 mm of ring-shaped electrode part). Calculate the current value after applying a voltage of 500 V for 10 seconds under a / 55% RH environment.
^{Here, 2.011 shown in the above equation is an electrode coefficient for converting to resistivity, and is πd 2} / from the outer diameter d (mm) of the columnar electrode portion and the sample thickness t (cm). It is calculated as 4t. The thickness of the conductive foamed member is measured using an eddy current type film thickness meter CTR-1500E manufactured by Sanko Denshi Co., Ltd.

The shape and thickness of the conductive foamed member according to the present embodiment are not particularly limited and may be appropriately selected depending on the intended use. For example, when the conductive foamed member according to the present embodiment is used for the transfer roll, the thickness of the conductive foamed member is preferably 2 mm or more and 20 mm or less, and more preferably 2 mm or more and 15 mm or less.

<Manufacturing method of conductive foam member>
The method for producing the conductive foamed member according to the present embodiment is not particularly limited, but at least one resin A selected from the group consisting of nitrile rubber, chloroprene rubber and hydride nitrile rubber, and styrene butadiene rubber (SBR). ) And at least one resin B selected from the group consisting of epichlorohydrin-based rubber, ethylene-propylene-diene rubber, carbon black, peroxide, and a foaming agent. , And a production method including a step of cross-linking (peroxide cross-linking) and foaming the composition to obtain a foamed resin is preferable.
Regarding the preferred embodiments of the resin A, the resin B, the ethylene-propylene-diene rubber, the carbon black, the peroxide, and the foaming agent in the method for producing the conductive foamed member according to the present embodiment, the conductive foamed according to the present embodiment. The same applies to the preferred embodiments of the resin A, the resin B, the ethylene-propylene-diene rubber, the carbon black, the peroxide, and the foaming agent described above in the member.
Crosslinking and foaming in the step of obtaining the foamed resin may be performed simultaneously or sequentially. When it is carried out sequentially, it is preferable to carry out cross-linking and then foam.
The temperature and time at the time of crosslinking and foaming are not particularly limited and may be appropriately set according to the peroxide and foaming agent used.
Crosslinking and foaming are preferably performed by heating, and the heating temperature is preferably 50 ° C. or higher and 170 ° C. or lower.

<Transfer roll>
The transfer roll according to the present embodiment is a transfer roll having the conductive foaming member according to the present embodiment, and the support and the conductive foaming member according to the present embodiment arranged on the outer peripheral surface of the support are provided. It is preferable to have a layer containing the support, and it is more preferable to have a layer composed of the support and the conductive foamed member according to the present embodiment arranged on the outer peripheral surface of the support.

The support used for the transfer roll is a member that functions as an electrode and a support member of the transfer roll.
Examples of the support include metal members such as iron (free-cutting steel and the like), copper, brass, stainless steel, aluminum, and nickel.
Further, examples of the support include a member whose outer surface is plated (for example, a resin or ceramic member), a member in which a conductive agent is dispersed (for example, a resin or ceramic member), and the like.
Further, the support may be a hollow member (cylindrical member) or a non-hollow member.
Further, the size and shape of the support are not particularly limited and may be appropriately set according to a desired application.

<Image forming device and process cartridge>
The image forming apparatus according to the present embodiment is an image forming apparatus having a conductive foam member according to the present embodiment, and is preferably an image forming apparatus having a transfer roll according to the present embodiment. A charging means for charging the image holder, a latent image forming means for forming a latent image on the surface of the charged image holder, and a latent image formed on the surface of the image holder are developed with toner to develop a toner. An image forming apparatus including a developing means for forming an image and a transfer means having a transfer roll according to the present embodiment and transferring a toner image formed on the surface of the image holder to a recording medium. More preferred.

In the transfer means, for example, a direct transfer method configuration to a recording medium provided with a transfer roll alone, or an intermediate transfer body and the surface of the image holder on which the toner image formed on the surface of the image holder is transferred. The configuration of the intermediate transfer method includes a primary transfer roll that transfers the formed toner image to the surface of the intermediate transfer body and a secondary transfer roll that transfers the toner image transferred to the surface of the intermediate transfer body to a recording medium. To be done.
In the direct transfer method configuration, it is preferable to include the transfer roll according to the present embodiment as the transfer roll arranged so as to face the image holder.
Further, in the configuration of the intermediate transfer method, it is preferable to include the transfer roll according to the present embodiment as at least one transfer roll of the primary transfer roll and the secondary transfer roll.

Examples of the image forming apparatus according to the present embodiment include a normal monocolor image forming apparatus that accommodates only monochromatic toner in a developing apparatus, and a toner image held on an image holder is directly transferred to a recording medium. A plurality of image holders equipped with an image forming apparatus, a color image forming apparatus for sequentially repeating primary transfer of a toner image held on an image holder to an intermediate transfer body, and a developing device for each color are serially mounted on the intermediate transfer body. It may be any of the tandem type color image forming apparatus arranged in.

The process cartridge according to the present embodiment is a process cartridge having the conductive foamed member according to the present embodiment, preferably a process cartridge having a transfer roll according to the present embodiment, and the transfer roll according to the present embodiment is used. It is more preferable that the process cartridge has a transfer means for transferring the toner image formed on the surface of the image holder to the recording medium, and is attached to and detached from the image forming apparatus.
Further, the process cartridge according to the present embodiment includes an image holder, a charging means for charging the image holder, a latent image forming means for forming a latent image on the surface of the charged image holder, and an image holder, if necessary. At least one means selected from the developing means for developing the latent image formed on the surface of the body with toner to form the toner image may be provided.

Hereinafter, the image forming apparatus according to the present embodiment will be described 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 shown in FIG. 1 is an electrophotographic first to output images of each color of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. A fourth image forming unit 10Y, 10M, 10C, 10K (image forming means) is provided. These image forming units (hereinafter, simply referred to as “units”) 10Y, 10M, 10C, and 10K are arranged side by side at a specific distance from each other in the horizontal direction. The units 10Y, 10M, 10C, and 10K may be process cartridges that can be attached to and detached from the image forming apparatus main body.

An intermediate transfer belt 20 as an intermediate transfer body is arranged above each unit 10Y, 10M, 10C, and 10K in the drawing. The intermediate transfer belt 20 is wound by applying tension to the drive rolls 22 arranged apart from each other from the left to the right in FIG. 1 and the support roll 24 in contact with the inner surface of the intermediate transfer belt 20 from the first unit 10Y. The 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 or the like (not shown), and a specific tension is applied to the intermediate transfer belt 20 wound around the support roll 24. Further, an intermediate transfer body cleaning device 30 is provided on the side surface of the image holder of the intermediate transfer belt 20 so as to face the drive roll 22.
Further, each of the developing devices (developing means) 4Y, 4M, 4C, and 4K of each unit 10Y, 10M, 10C, and 10K has yellow, magenta, cyan, and black contained in the toner cartridges 8Y, 8M, 8C, and 8K, respectively. 4 color toners can be supplied.

Since the first to fourth units 10Y, 10M, 10C, and 10K described above have the same configuration, here, the first unit 10Y forming a yellow image arranged on the upstream side in the traveling direction of the intermediate transfer belt. Will be explained on behalf of. The second to fourth units are provided with reference numerals with magenta (M), cyan (C), and black (K) instead of yellow (Y) in the portion equivalent to the first unit 10Y. The description of 10M, 10C, and 10K will be omitted.

The first unit 10Y has a photoconductor 1Y that acts as an image holder. Around the photoconductor 1Y, a charge roll 2Y that charges the surface of the photoconductor 1Y to a specific potential, and a laser beam 3Y based on a color-separated image signal expose the charged surface to form a static charge image. Exposure device 3, developing device (development means) 4Y that supplies charged toner to the electrostatic charge image to develop the electrostatic charge image, and primary transfer roll 5Y (primary) that transfers the developed toner image onto the intermediate transfer belt 20. The transfer means) and the photoconductor cleaning device (cleaning means) 6Y that removes the toner remaining on the surface of the photoconductor 1Y after the primary transfer with a cleaning blade are arranged in this order.
The primary transfer roll 5Y is arranged inside the intermediate transfer belt 20 and is provided at a position facing the photoconductor 1Y. Further, a bias power supply (not shown) for applying a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power supply changes the transfer bias applied to each primary transfer roll by control by a control unit (not shown).

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

The electrostatic charge image is an image formed on the surface of the photoconductor 1Y by charging, and the laser beam 3Y reduces the specific resistance of the irradiated portion of the photosensitizing layer, and the charged charge on the surface of the photoconductor 1Y flows. On the other hand, it is a so-called negative latent image formed by the residual charge of the portion not irradiated with the laser beam 3Y.
The electrostatic charge image formed on the photoconductor 1Y in this way is rotated to a specific developing position as the photoconductor 1Y travels. Then, at this developing position, the electrostatic charge image on the photoconductor 1Y is made into a visible image (developed image) by the developing device 4Y.

For example, yellow toner is housed in the developing apparatus 4Y. The yellow toner is triboelectrically charged by being agitated inside the developing apparatus 4Y, and has a charge having the same polarity (negative electrode property) as the charged charge on the photoconductor 1Y, and is a developer roll (developer holder). It is held on. Then, as the surface of the photoconductor 1Y passes through the developing device 4Y, the yellow toner is electrostatically adhered to the statically eliminated latent image portion on the surface of the photoconductor 1Y, and the latent image is developed by the yellow toner. .. The photoconductor 1Y on which the yellow toner image is formed is continuously traveled at a specific speed, and the toner image developed on the photoconductor 1Y is conveyed to a specific primary transfer position.

When the yellow toner image on the photoconductor 1Y is conveyed to the primary transfer unit, a specific primary transfer bias is applied to the primary transfer roll 5Y, and the electrostatic force from the photoconductor 1Y to the primary transfer roll 5Y is applied to the toner. The toner image on the photoconductor 1Y is transferred onto the intermediate transfer belt 20 by being acted on by the image. 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, for example.
On the other hand, the toner remaining on the photoconductor 1Y is removed by the cleaning device 6Y and recovered.

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 is transferred in 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 multiplex transferred.

The intermediate transfer belt 20 on which the toner images of four colors are multiplex-transferred through the first to fourth units is arranged on the image holding surface side of the support roll 24 and the intermediate transfer belt 20 in contact with the intermediate transfer belt 20 and the inner surface of the intermediate transfer belt 20. It leads to a secondary transfer unit composed of the secondary transfer roll (secondary transfer means) 26. A cleaning blade 27 made of an elastic material is in contact with the outer peripheral surface of the secondary transfer roll 26, and the cleaning blade 27 is not transferred from the intermediate transfer belt 20 to the recording medium P but is transferred to the outer peripheral surface of the secondary transfer roll 26. The adhered toner is removed.

On the other hand, the recording medium P is fed to the gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are in contact with each other 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 is (-) polarity, which is the same polarity as the polarity (-) of the toner, and the electrostatic force from the intermediate transfer belt 20 toward the recording medium P is applied to the toner image, and the transfer bias is applied to the toner image. The toner image of is transferred onto the recording medium P. The secondary transfer bias at this time is determined according to the resistance detected by the resistance detecting means (not shown) that detects the resistance of the secondary transfer unit, and is voltage controlled.

After that, the recording medium P is sent to the fixing device (fixing means) 28 to heat the toner image, and the color-overlapped toner image is melted and fixed on the recording medium P. The recording medium P for which the color image has been fixed is carried out toward the discharge unit, and a series of color image forming operations is completed.

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

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

(Example 1)
As rubber components, 30 parts of hydrogenated acrylonitrile butadiene rubber (H-NBR, Zetpol 2020 manufactured by Nippon Zeon Co., Ltd.), 40 parts of EPDM (ethylene-propylene-diene rubber, Esplen 505 manufactured by Sumitomo Chemical Co., Ltd.), GECO ( Add 30 parts of epichlorohydrin-ethylene oxide-allylglycidyl ether copolymer, Epichromer CG-102 manufactured by Osaka Soda Co., Ltd., ethylene oxide (EO) = 56%), knead with a pressure kneader, and chemically foam. 7 parts of 4,4'-oxybisbenzenesulfonyl hydrazide (OBSH) as an agent, 12 parts of acetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd., DBP oil absorption = 212 ml / 100 g) as a filler, thermal black (Asahi Carbon Co., Ltd.) ), DBP oil absorption = 103 ml / 100 g) 23 parts, magnesium oxide (manufactured by Kyowa Chemical Co., Ltd.) 5 parts, stearic acid 1 part, peroxide (p, p'-oxybenzenesulfonyl hydrazide, Eiwa Kasei Kogyo ( Six parts of Neocerbon N # 100s) manufactured by Co., Ltd. were added and further kneaded with two heating rolls. This mixture is inserted into a SUS core metal (6 mmφ), extruded into a roll, cut into a fixed size from a microwave vulcanization (UHF) furnace via a hot air vulcanizer, and dropped to 18.7 mmφ by cylindrical polishing. A conductive foam roll (foam hardness C = 33, 6.8 product, volume resistance value at direct current (DC) 1 kV) was prepared. Using a DocuCenter-III 3000 PF manufactured by Fuji Xerox Co., Ltd., the obtained conductive foam roll was used to observe environmental changes in the resistance value of the nip portion after running 800,000 sheets on the transfer roll. The change in electrical resistance (amount of environmental change) between low temperature and low humidity (15 ° C, 30% RH) and high temperature and high humidity (30 ° C, 85% RH) is 0.7 digits, and the amount of environmental change after running changes. There wasn't.

(Example 2)
The H-NBR described in Example 1 is CR (chloroprene, Neoprene WRT manufactured by Showa Denko Co., Ltd.), and the GECO described in Example 1 is Epichromer CG-107 (GECO, EO =) manufactured by Osaka Soda Co., Ltd. It was processed in the same manner as in Example 1 except that it was set to 41%) to obtain a conductive foamed roll (hardness 30, 7.8 product). The amount of environmental change was 0.5 digits, and similarly, the amount of environmental change after running was 0.6 digits, and the change was small.

(Example 3)
A conductive foamed roll was obtained by processing in the same manner as in Example 1 except that the GECO described in Example 1 was Epion 301 (GECO, EO = 56%) manufactured by Osaka Soda Co., Ltd. (hardness 35, 7.3 Vehicles). The amount of environmental change was 0.9 digits, and the environmental change after running did not change.

(Example 4)
The GECO described in Example 1 was SBR (styrene butadiene rubber, JSR 1502 manufactured by JSR Corporation) and processed in the same manner as in Example 1 except that magnesium oxide was not added to obtain a conductive foamed roll. (Hardness 35, 6.8 vehicles). The amount of environmental change was 1.4 digits, which was ionic conductivity, and the amount of environmental change after running was 0.8 digits.

(Comparative Example 1)
The H-NBR described in Example 1 was NBR (acrylonitrile butadiene rubber, Nipol DN401LL manufactured by Nippon Zeon Co., Ltd.), and a sulfur vulcanizer (Sulfax PMC manufactured by Tsurumi Chemical Industry Co., Ltd.) was used instead of the peroxide. ) 1 part, 1 part of vulcanization accelerator (Noxeller TS, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.), and 1 part of vulcanization accelerator (Noxeller DT, manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.) were used. Except for the above, it was processed in the same manner as in Example 1 to obtain a conductive foamed roll (surface hardness 38, 7.0-vehicle product). The obtained conductive foam roll was subjected to a running test with DCIII-3000PF manufactured by Fuji Xerox Co., Ltd., and as a result of measuring the environmental change in the same manner after the test, the initial single digit environmental change amount was 1.8 digits. Increased to, and deteriorated in ionic conductivity.

<Evaluation>
The following evaluations were performed on each of the obtained conductive foam rolls.

(Ozone resistance)
The roll after being left in the ozone chamber at an ozone concentration of 1 ppm for 72 hours was cut to a length of 1 cm, the cross section was compressed by 30%, and then left for 1 day to check its recovery.
The recovery rate from the initial height ((initial height-height over time) x 100 / initial height) was evaluated.
A: 20% or less B: More than 20% and less than 30% C: 30%

(Resistance stability)
A roll having the same composition was placed on the transfer roll 5 shown in FIG. 1, and the resistance change of the roll run under low temperature / low humidity (10 ° C., 30% RH) for 300 k cycles was changed from the initial stage to high temperature / high humidity (30 ° C., 30% RH). The environmental fluctuation range (Δlog digit difference) of the resistance value between 30 ° C. and 80% RH) was evaluated.
A: Less than 0.5 digits B: 0.5 digits or more and less than 1 digit C: 1 digit or more

(Permanent distortion inhibitory property)
The roll was cut to a length of 1 cm in a 70 ° C. chamber, the cross section was compressed by 30% and left to stand for 72 hours, and then the roll was taken out and left to stand for 1 day to check its recovery.
The recovery rate from the initial height ((initial height-height over time) x 100 / initial height) was evaluated.
A: 20% or less B: More than 20% and less than 30% C: 30%

Tables 1 and 2 list the compounding composition of the conductive foamed rolls of each example at the time of producing the foamed resin and the evaluation results.

1Y, 1M, 1C, 1K photoconductor (example of image holder)
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 beam 4Y, 4M, 4C, 4K developing device (example of developing means)
5Y, 5M, 5C, 5K primary transfer roll (example of primary transfer means)
6Y, 6M, 6C, 6K Photoreceptor cleaning device (an example of cleaning means)
8Y, 8M, 8C, 8K Toner Cartridge 10Y, 10M, 10C, 10K Image Forming Unit 20 Intermediate Transfer Belt (Example of Intermediate Transfer)
22 Drive roll 24 Support roll 26 Secondary transfer roll (an example of secondary transfer means)
30 Intermediate transfer cleaning device P Recording paper (an example of recording medium)

Claims (10)

And the resin A is a water hydride nitrile rubber, at least one resin B is selected from styrene-butadiene rubber and epichlorohydrin-based group consisting of rubbers, ethylene - propylene - a diene peroxide crosslinking and foaming Foamed resin and
Conductive foam member containing carbon black. The conductive foamed member according to claim 1, wherein the resin B contains an epichlorohydrin-ethylene oxide-allyl glycidyl ether copolymer. The conductive foamed member according to claim 1 or 2, wherein the content of the resin B in the foamed resin is 30% by mass or less with respect to the total mass of the foamed resin. The conductive foamed member according to any one of claims 1 to 3, wherein the carbon black contains two or more types of carbon black having different oil absorbency. The conductive foamed member according to any one of claims 1 to 4, wherein the resin B contains styrene-butadiene rubber. The conductive foaming member according to any one of claims 1 to 5, further comprising at least one compound selected from the group consisting of zinc oxide and magnesium oxide. And the resin A is a water hydride nitrile rubber, at least one resin B is selected from styrene-butadiene rubber and epichlorohydrin-based group consisting of rubbers, ethylene - propylene - and diene rubber, and carbon black, peroxide The method for producing a conductive foamed member according to any one of claims 1 to 6 , which comprises a step of cross-linking and foaming a composition containing the foaming agent and a foaming agent to obtain a foamed resin. A transfer roll having the conductive foamed member according to any one of claims 1 to 6. A process cartridge having the transfer roll according to claim 8 , comprising a transfer means for transferring a toner image formed on the surface of an image holder to a recording medium, and being attached to and detached from an image forming apparatus. Image holder and
A charging means for charging the image holder and
A latent image forming means for forming a latent image on the surface of the charged image holder, and
A developing means for developing a latent image formed on the surface of the image holder with toner to form a toner image, and
A transfer means having the transfer roll according to claim 8 and transferring a toner image formed on the surface of the image holder to a recording medium.
An image forming apparatus comprising.

Images