JP2019123852A - Rubber composition, rubber roller and image formation apparatus - Google Patents

Abstract

To provide a rubber composition that can reduce an average cell diameter of a foamed cell and also reduce variations in cell diameter, can form an image having a good image quality by suppressing contamination due to migration of components on a member or a sheet through contact therewith, and constitutes a porous body of a roller body or the like, to provide a rubber roller including a roller body composed of a porous body produced by foaming and crosslinking the rubber composition, and to provide an image formation apparatus including the rubber roller.SOLUTION: The rubber composition is produced by blending, into rubber including a diene rubber, at least one kind selected from the group consisting of ethylene/propylene rubbers, and an ion conductive rubber, at least one kind of fine porous particle selected from the group consisting of zeolite, active charcoal and diatomaceous earth together with a crosslinking component and a foaming component. A rubber roller 1 comprises a roller body 2 formed by extruding the rubber composition into a cylindrical shape and crosslinking the same. An image formation apparatus has the rubber roller 1 incorporated therein.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a rubber composition, a rubber roller including a roller main body formed of a porous body formed by molding, foaming, and crosslinking the rubber composition, and an image forming apparatus including the rubber roller.

For example, in image forming apparatuses using electrophotography, such as laser printers, electrostatic copiers, plain paper facsimile machines, or composite machines of these, with the recent market maturation, the height of formed images has become high. There is a tendency that image quality improvement and speeding up of image forming speed are required.
The transfer roller or the like which is one of the parts of the image forming apparatus includes, for example, a rubber composition containing rubber, a crosslinking component, a foaming component and the like and to which conductivity is imparted, which is formed into a tubular shape and then foamed or crosslinked. A rubber roller including a porous and conductive roller main body formed by the above method is used (Patent Document 1).

In order to satisfy the above requirements, such a rubber roller is required to have an average cell diameter of foamed cells exposed on the outer peripheral surface of the roller main body, that is, an average cell diameter as small as possible and a small cell diameter variation. Be
As described above, the roller body is generally formed by forming the rubber composition into a cylindrical shape, foaming and crosslinking, and then polishing the outer peripheral surface thereof to a predetermined outer diameter. is there.

Therefore, in order to reduce the variation of the average cell diameter and the cell diameter of the foamed cells exposed on the outer peripheral surface after polishing, the average cell diameter of the entire roller main body must be reduced and the variation of the cell diameter should be reduced. It does not.
However, in the prior art, although depending on, for example, the balance of viscosity, crosslinking degree, kind of foaming component and blending ratio of the rubber composition, the average cell diameter of the foamed cells is smaller than the present condition or variation of cell diameter. At present, it is becoming difficult to reduce the

That is, there is a limit to the range in which the average cell diameter of the foamed cells can be reduced even if the type, particle size, mixing ratio, etc. of the foaming agent as the foaming component are adjusted.
In addition, as the average cell diameter is reduced, foaming is destabilized, and the cell diameter of individual foamed cells is more likely to vary. Then, for example, there is a tendency to easily include foam cells having a cell diameter much larger than the average cell diameter.

When such a foamed cell having a large cell diameter is exposed to the outer peripheral surface of the roller main body by polishing, when the rubber roller provided with the roller main body is used as, for example, a transfer roller, the image quality of the formed image is deteriorated. Produces
In general, the roller body is disposed in the image forming apparatus such that the outer peripheral surface thereof is in direct contact with members such as the photosensitive member and the belt.

Further, in the case of the transfer roller, the outer peripheral surface of the roller main body is in direct contact with the sheet for image formation.
However, the roller body sometimes contains a component that exudes to the outer peripheral surface of the roller body when a pressure contact force is applied, for example.
Then, when such a component exudes to the outer peripheral surface, it shifts to a member or sheet such as a photosensitive member or the like in direct contact with the outer peripheral surface, contaminates the member or sheet, and causes deterioration of the image quality of the formed image. There is also a problem such as

JP, 2013-067722, A JP, 2006-178128, A

The object of the present invention is to make it possible to make the average cell diameter of the foamed cells smaller than in the present situation and to stably foam so that the variation of the cell diameter can be reduced, and the contacting members and sheets are contaminated by the migration of components. It is an object of the present invention to provide a rubber composition which is the basis of a porous body such as a roller main body which can form an image of good image quality.
Another object of the present invention is to provide a rubber roller including a roller main body made of a porous body obtained by foaming and crosslinking the rubber composition, and an image forming apparatus including the rubber roller.

The present invention is a rubber composition for forming a porous body used in an image forming apparatus utilizing electrophotography,
A rubber comprising an ion conductive rubber, and at least one member selected from the group consisting of a diene rubber and an ethylene propylene rubber,
A crosslinking component for crosslinking the rubber,
The three components of the present invention include a foaming component for foaming the rubber, and at least one fine porous particle selected from the group consisting of zeolite, activated carbon, and diatomaceous earth, per 100 parts by mass of the total amount of the rubber. The blending ratio P of the total of the fine porous particles is represented by the formula (1):
P ≦ Z × 35 + C × 20 + D × 35 (1)
[In the formula, Z represents zeolite, C represents activated carbon, D represents diatomaceous earth, and the mass ratio of each of the three types of fine porous particles is 1]. ]
The rubber composition satisfies

The present invention is also a rubber roller comprising a porous roller main body, which is made of the above rubber composition.
Furthermore, the present invention is an image forming apparatus including the rubber roller.

According to the present invention, it is possible to make the average cell diameter of the foamed cells smaller than in the present situation, and to stably foam so that the variation of the cell diameter can be reduced, and the contacting members and sheets are contaminated by the migration of components. It is possible to provide a rubber composition which is the basis of a porous body such as a roller body and the like, which can form an image of good image quality.
Further, according to the present invention, it is possible to provide a rubber roller including a roller main body made of a porous body obtained by foaming and crosslinking such a rubber composition, and an image forming apparatus including the rubber roller.

It is a perspective view showing an example of an embodiment of a rubber roller of the present invention. It is a figure explaining the method to measure the roller resistance value of a rubber roller.

<< Rubber composition >>
As described above, the present invention is a rubber composition for forming a porous body used in an image forming apparatus utilizing electrophotography.
A rubber comprising an ion conductive rubber, and at least one member selected from the group consisting of a diene rubber and an ethylene propylene rubber,
A crosslinking component for crosslinking the rubber,
The three components of the present invention include a foaming component for foaming the rubber, and at least one fine porous particle selected from the group consisting of zeolite, activated carbon, and diatomaceous earth, per 100 parts by mass of the total amount of the rubber. The blending ratio P of the total of the fine porous particles is represented by the formula (1):
P ≦ Z × 35 + C × 20 + D × 35 (1)
[In the formula, Z represents zeolite, C represents activated carbon, D represents diatomaceous earth, and the mass ratio of each of the three types of fine porous particles is 1]. ]
It is characterized by satisfying.

According to the present invention, zeolite, activated carbon, or diatomaceous earth, which are fine porous particles each having a fine porous structure, adsorbs a part of the gas generated from the foaming component during foaming of the rubber composition, It functions to reduce the foaming of the rubber composition.
Therefore, for example, when the roller main body of the rubber roller is formed as a porous body, the average cell diameter of the whole roller main body can be reduced, and the variation in cell diameter can be reduced.

Therefore, the variation in the average cell diameter and the cell diameter of the foamed cells exposed on the outer peripheral surface of the roller main body by polishing can also be reduced.
In addition, the component that is transferred to the contacting member or sheet and causes contamination is, for example,
・ It is contained in the rubber composition as it occurs when the rubber composition is prepared by kneading the rubber etc.
・ It occurs when molding the rubber composition into the shape of a porous body and crosslinking it,
・ It is generated by the subsequent use of porous material.

On the other hand, according to the present invention, the zeolite, activated carbon or diatomaceous earth, which is a fine porous particle, continuously adsorbs the generated components into the porous structure after the preparation of the rubber composition. It also functions to suppress exudation of the component to the surface of the porous body.
Therefore, for example, when forming a roller main body of a rubber roller as a porous body, a member which directly contacts the outer peripheral surface in the image forming apparatus while suppressing the leaching of the above components to the outer peripheral surface of the roller main body It is also possible to prevent the paper from being contaminated by migration of components.

Examples of components that cause contamination include residues of crosslinking components and the like.
Also, for example, relatively low molecular weight components such as those derived from polymers which are generated at the time of crosslinking reaction, and when epichlorohydrin rubber or chloroprene rubber is used as rubber, chlorine gas generated from these rubbers at the time of crosslinking , One of the components that cause pollution.

When an acid acceptor such as hydrotalcite is blended, the acid acceptor functions to capture chlorine in a chlorine-based gas by the anion exchange ability.
Therefore, it is possible to suppress to some extent that the chlorine-based gas remains free in the crosslinked rubber roller or the remaining chlorine-based gas is transferred to a contacting member or sheet.

However, the other components can not suppress migration even if they contain an acid acceptor.
In particular, when the rubber roller is used as a transfer roller and pressed against the photosensitive member with a predetermined pressure, for example, when left to stand for a certain period in a high temperature and high humidity environment, the above components become the outer periphery of the roller body It exudes to the surface and shifts to a photosensitive member or the like, which tends to cause an image defect of the formed image.
On the other hand, according to the present invention, due to the functions of zeolite, activated carbon and diatomaceous earth compounded as fine porous particles, the component which becomes a source of contamination is a roller even if it is allowed to stand for a fixed period under the above-mentioned conditions. It is possible to suppress the exudation to the outer peripheral surface of the main body and the transfer to the photosensitive member or the like.

Therefore, when the rubber roller provided with the above-mentioned roller main body is used as a transfer roller, for example, the image quality of the formed image can be improved by the synergetic effect of each function mentioned above.
These things are clear also from the result of the example mentioned later and a comparative example.
<Fine porous particles>
As the fine porous particles, at least one selected from the group consisting of the above-mentioned zeolite, activated carbon, and diatomaceous earth having any shape such as powdery, powdery or particulate form is used. it can.

(Zeolite)
As the zeolite, as described above, various zeolites having a function of adsorbing a gas generated from a foaming component at the time of foaming of the rubber composition or a component which causes contamination can be used.
Specifically, the zeolite includes, for example, a hydrous alkali metal salt or alkaline earth metal salt of a crystalline aluminosilicate which is one of clay minerals, and has a three-dimensional network structure including fine pores at the molecular level. And various natural zeolites derived from natural products.

Further, as the zeolite, for example, synthetic zeolite synthesized using various chemical substances as a starting material, or artificial zeolite regenerated from coal ash, paper sludge incinerator ash or the like can also be used.
Specific examples of the zeolite include, for example, chabazite, faujasite, ashcurofutin, chabazite, gmelin zeolite, levinite, wool zeolite, thomson zeolite, soda zeolite, morden zeolite, gismondite, ezingonite, gonnalite, epidesmin, turbidite , Zeolite, fluorite, hiru Zeolite, Laubanite, Pavenite, Brewsterite, Epistilbite, Wellsite, Mesoquartz, Cyanolite, Zeolite P, Zeolite X, Zeolite Y, Zeolite T, Zeolite A, Zeolite L, etc. Be

One or more of these zeolites can be used.
(Activated carbon)
As the activated carbon, it is possible to use various activated carbons produced by various production methods and having a function of adsorbing a gas generated from a foaming component at the time of foaming of a rubber composition or a component serving as a source of contamination.

As a method for producing activated carbon, for example, a gas activation method in which a raw material is activated by being brought into contact with an activating gas such as steam, carbon dioxide, air or combustion gas at high temperature, or the raw material is impregnated with a zinc chloride solution, The chemical activation method etc. which heat in an inert gas stream, carbonize, and activate are mentioned.
Among them, as a raw material for producing activated carbon by the gas activation method, for example, wood, fruit shell (such as coconut shell), carbide such as bamboo and synthetic resin, lignite, peat, bituminous coal, coal such as coal char, Oil residue and other carbides may be mentioned.

Moreover, as a raw material which manufactures activated carbon by a chemical activation method, saw dust etc. are mentioned, for example.
One or more of these activated carbons can be used.
(Diatomaceous earth)
As diatomaceous earth, various diatomaceous earths having a function of adsorbing a gas generated from a foaming component upon foaming of a rubber composition, or a component which causes contamination can be used.

As such a diatomaceous earth, for example, various diatomaceous earths obtained by grinding the diatomaceous earth, which is a deposit mainly composed of the remains of single-celled algae diatomaceous earth, to an arbitrary particle size, and purifying it as necessary Can be used.
One or two or more of these diatomaceous earths can be used.
(Blending ratio)
The total blending ratio P of the three types of fine porous particles of zeolite, activated carbon and diatomaceous earth per 100 parts by mass of the rubber is, as described above, the formula (1):
P ≦ Z × 35 + C × 20 + D × 35 (1)
[In the formula, Z represents zeolite, C represents activated carbon, D represents diatomaceous earth, and the mass ratio of each of the three types of fine porous particles is 1]. ]
You need to be satisfied.

For example, when the fine porous particles are only zeolite (including the case where two or more types of zeolite are used in combination, the same shall apply hereinafter), Z = 1, C = 0, D = 0 in the formula (1) Therefore, the blending ratio P of the zeolite is limited to 35 parts by mass or less per 100 parts by mass of the total amount of rubber.
When the fine porous particles are only activated carbon, Z = 0, C = 1 and D = 0 in the formula (1), so the blending ratio P of activated carbon is 20 mass per 100 mass parts of the total amount of rubber. Limited to part or less.

When the fine porous particles are only diatomaceous earth, Z = 0, C = 0, and D = 1 in the formula (1), so the mixing ratio P of diatomaceous earth is 35 mass per 100 mass parts of the total amount of rubber. Limited to part or less.
Furthermore, when the fine porous particles contain zeolite, activated carbon, and diatomaceous earth in the same amounts, respectively, Z = 1/3, C = 1/3, and D = 1/3 in Formula (1), The blending ratio P of the total of the three types of microporous particles is limited to 30 parts by mass or less per 100 parts by mass of the total amount of rubber.

When the blending ratio P of the total of the fine porous particles is larger than the respective ranges described above, the roller body after crosslinking becomes too hard and, for example, adequate flexibility suitable for use as a transfer roller can be obtained. It may not be.
Moreover, the viscosity at the time of heat-melting of the rubber composition before bridge | crosslinking may rise, and the processability of the said rubber composition may fall.

On the other hand, by setting the blending ratio P of the fine porous particles in the above range, it is possible to maintain good flexibility of the roller body or good processability of the rubber composition.
However, when there are too few fine porous particles, a part of the gas generated from a foaming ingredient at the time of foaming of a rubber composition mentioned above by blending the said fine porous particles is adsorbed, and the said rubber composition In some cases, the function of alleviating the foaming of the product may not be obtained.

Then, for example, there are cases where the average cell diameter of the foamed cells exposed on the outer peripheral surface of the roller body of the rubber roller can not be reduced or the variation in cell diameter can not be reduced.
Moreover, the component which causes the contamination mentioned above may be adsorbed, and the effect which suppresses the contamination by the transfer of the said component, and the fall of the image quality by it may not fully be acquired.
Therefore, the blending ratio of the fine porous particles is preferably 1 part by mass or more, particularly 3 parts by mass or more in the above range.

The lower limit value is the lower limit value of the blending ratio of the fine porous particles when only one of zeolite, activated carbon or diatomaceous earth is used as the fine porous particles.
Moreover, when using together 2 or more types of fine porous particles, it is a lower limit of the compounding ratio of the sum total.
The reason why the upper limit of the blending ratio of activated carbon is smaller than in the case of the other two types of fine porous particles is that activated carbon also functions as a reinforcing agent for rubber, and even if the blending of smaller amounts than the other two types, This is because there is a tendency to harden the roller body after crosslinking.

In addition, when the activated carbon has electron conductivity and is compounded in a large amount, the roller resistance value of the rubber roller after crosslinking may be, for example, too lower than the range suitable as a transfer roller.
In addition, in patent document 1 mentioned above, the zeolite is described as an example of the filler which may be mix | blended with a rubber composition.

However, in the invention described in Patent Document 1, zeolite is merely exemplified as one of various fillers such as carbon black and the like, and an embodiment in which the effect is actually verified by blending zeolite is a patent It is not included in reference 1.
Further, in Patent Document 1, when fine porous particles such as zeolite are blended,
・ Relax the foaming of the rubber composition to make the average cell diameter of the foamed cells smaller than the present condition, reduce the variation of the cell diameter, or · adsorb the component that causes the contamination, Control the contamination of parts and paper by
No mention is made of the fact that it is possible to form an image of good image quality, which is unique to the present invention.

Further, in Patent Document 2, a rubber composition in which a porous filler (fine porous particles) such as zeolite is further blended with a silicone rubber containing a foaming agent is molded into a cylindrical shape, foamed and crosslinked to form a fixing roller. It is stated that forming.
The porous filler adsorbs the gas in the foam expanded by heating in the formed fixing roller, and functions to suppress the thermal expansion of the fixing roller due to the temperature rise.

However, zeolite based on crystalline aluminosilicate, activated carbon based on carbon, and diatomaceous earth based on silicon dioxide all have higher affinity to silicone rubber than other rubbers. .
Therefore, when the fine porous particles and the silicone rubber are combined, the silicone rubber in the molten state is adsorbed to many of the fine pores of the fine porous particles, and the component which is the source of gas or contamination is Not adsorbed enough.

Therefore, in combination with silicone rubber, the gas is adsorbed to reduce the average cell diameter of the foamed cell and its variation, or the component that causes contamination is adsorbed, and the transfer of the component contaminates the member and the paper. It is not possible to obtain the effect of suppressing
This is also apparent from the results of Examples, Comparative Examples, and Conventional Examples described later.
<Rubber>
As the rubber, as described above, at least a diene rubber and / or an ethylene propylene rubber and an ion conductive rubber are used in combination.

In particular, it is preferable to use only a diene rubber and / or an ethylene propylene rubber and an ion conductive rubber as a rubber in a state that does not include (exclude) other rubber such as silicone rubber.
Among them, diene rubber and / or ethylene propylene rubber functions to impart, in particular, good properties as a rubber, that is, a property of being flexible, having a small compression set, and less likely to cause setter, to the roller body.

In addition, the ion conductive rubber functions to impart appropriate ion conductivity to the roller body to adjust the roller resistance value of the rubber roller, for example, in a range suitable as a transfer roller.
(Diene rubber)
Examples of the diene rubber include natural rubber, isoprene rubber (IR), acrylonitrile butadiene rubber (NBR), styrene butadiene rubber (SBR), butadiene rubber (BR), chloroprene rubber (CR) and the like.

In particular, as the diene rubber, at least one of three types of NBR, SBR and BR is preferable.
・ NBR
As NBR, low nitrile NBR having an acrylonitrile content of 24% or less, medium nitrile NBR having 25 to 30%, medium high nitrile NBR having 31 to 35%, high nitrile NBR having 36 to 42%, 43% or more Any very high nitrile NBR can be used.

Further, as NBR, there are oil-extended type in which extension oil is added to adjust flexibility, and non-oil-expanded type in which extension oil is not added. In the present invention, in order to prevent contamination of photoreceptors etc. It is preferable to use a non-oil-extended type NBR which does not contain an extender oil which can be a bleed material.
One or two or more of these NBRs can be used.
・ SBR
As the SBR, any of various SBR synthesized by copolymerizing styrene and 1,3-butadiene by various polymerization methods such as an emulsion polymerization method and a solution polymerization method can be used.

Further, as SBR, there are high styrene type, medium styrene type and low styrene type SBR classified by styrene content, any of which can be used.
Furthermore, as SBR, there are oil-extended type in which extension oil is added to adjust flexibility, and non-oil-expanded type in which extension oil is not added, but in the present invention, in order to prevent contamination of photoreceptors etc. It is preferred to use a non-oil spread type SBR which does not contain an extender oil which can be a bleed material.

One or more of these SBRs can be used.
・ BR
As BR, any of various BRs having a polybutadiene structure in the molecule and having crosslinkability can be used.
In particular, high cis BR having a content of cis-1,4 bond of 95% or more is preferable, which can exhibit good properties as a rubber in a wide temperature range from low temperature to high temperature.

Also, as BR, there are oil-extended type in which extension oil is added to adjust the flexibility, and non-oil-extended type in which it is not added, but in the present invention, in order to prevent contamination of photoreceptors etc. It is preferable to use non-oil-extended BR which does not contain an extender oil which can be a bleed material.
One or more of these BR can be used.
(Ethylene-propylene rubber)
Examples of ethylene-propylene rubbers include ethylene-propylene rubber (EPM), which is a copolymer of ethylene and propylene, and ethylene-propylene-diene rubber (EPDM), which is a copolymer of ethylene, propylene and diene, and EPDM is particularly preferable. .

As the EPDM, various copolymers obtained by copolymerizing ethylene, propylene and diene can be used.
Examples of the diene include ethylidene norbornene (ENB) and dicyclopentadiene (DCPD).
Further, as EPDM, there are oil extension type in which extension oil is added to adjust flexibility, and non oil extension type in which extension oil is not added, but in the present invention, in order to prevent contamination of photoreceptors and the like as well. It is preferred to use a non-oil spread type EPDM which does not contain an extender oil which can be a bleed material.

One or two or more of these EPDMs can be used.
(Ion conductive rubber)
Examples of the ion conductive rubber include epichlorohydrin rubber and polyether rubber.
Among them, as epichlorohydrin rubber, for example, epichlorohydrin homopolymer, epichlorohydrin-ethylene oxide binary copolymer (ECO), epichlorohydrin-propylene oxide binary copolymer, epichlorohydrin-allyl glycidyl ether binary copolymer, epichlorohydrin- Ethylene oxide-allyl glycidyl ether terpolymer (GECO), epichlorohydrin-propylene oxide-allyl glycidyl ether terpolymer, epichlorohydrin-ethylene oxide-propylene oxide-allyl glycidyl ether tetrapolymer, etc. may be mentioned.

Further, examples of polyether rubbers include ethylene oxide-allyl glycidyl ether binary copolymers, ethylene oxide-propylene oxide-allyl glycidyl ether ternary copolymers, and the like.
Among them, copolymers containing ethylene oxide, in particular ECO and / or GECO are preferred.

The ethylene oxide content in ECO and / or GECO is preferably at least 30 mol%, more preferably at least 50 mol%, and preferably at most 80 mol%.
Ethylene oxide works to lower the roller resistance of the rubber roller.
However, if the ethylene oxide content is less than this range, such a function can not be obtained sufficiently, and the roller resistance value of the rubber roller may not be sufficiently reduced.

On the other hand, when the ethylene oxide content exceeds the above range, crystallization of ethylene oxide occurs and the segment movement of molecular chains is hindered, so the roller resistance of the rubber roller tends to increase.
Moreover, the roller body after crosslinking may become too hard, or the viscosity of the rubber composition before crosslinking may increase during heating and melting, and the processability of the rubber composition may decrease.

The epichlorohydrin content in ECO is the remaining amount of ethylene oxide content.
That is, the epichlorohydrin content is preferably 20 mol% or more, more preferably 70 mol% or less, and particularly preferably 50 mol% or less.
The allyl glycidyl ether content in GECO is preferably 0.5 mol% or more, more preferably 2 mol% or more, and preferably 10 mol% or less, particularly preferably 5 mol% or less.

Allyl glycidyl ether functions as a side chain to secure free volume, thereby suppressing the crystallization of ethylene oxide and reducing the roller resistance of the rubber roller.
However, if the content of allyl glycidyl ether is less than this range, such a function can not be sufficiently obtained, and thus the roller resistance value of the rubber roller may not be sufficiently reduced.

On the other hand, allyl glycidyl ether functions as a crosslinking point during GECO crosslinking.
Therefore, when the allyl glycidyl ether content exceeds the above range, the segmental motion of molecular chains is hindered by the fact that the crosslink density of GECO becomes too high, and the roller resistance value of the rubber roller tends to increase.
The epichlorohydrin content in GECO is the balance of ethylene oxide content and allyl glycidyl ether content.

That is, the epichlorohydrin content is preferably 10 mol% or more, particularly preferably 19.5 mol% or more, and more preferably 69.5 mol% or less, particularly preferably 60 mol% or less.
Incidentally, as GECO, in addition to the copolymer in the narrow sense obtained by copolymerizing the three types of monomers described above, a modified epichlorohydrin-ethylene oxide copolymer (ECO) modified with allyl glycidyl ether Things are also known.

Any GECO can be used in the present invention.
One or two or more of these ion conductive rubbers can be used.
(Blending ratio)
The compounding ratio of the ion conductive rubber is preferably 50 parts by mass or more, particularly 55 parts by mass or more, particularly 70 parts by mass or less, particularly preferably 65 parts by mass or less in 100 parts by mass of the total amount of rubber.

The blend ratio of the diene rubber and / or the ethylene propylene rubber is the remaining amount of the ion conductive rubber.
That is, when the blend ratio of the ion conductive rubber is set to a predetermined value within the above range, the blend ratio of the diene rubber and / or the ethylene propylene rubber is set such that the total amount of rubber is 100 parts by mass. Good.

If the blending ratio of the ion conductive rubber is less than the above range or exceeds the above range, the roller resistance value of the rubber roller may not be adjusted to a range suitable as a transfer roller, for example, in any of these cases.
In addition, when the blending ratio of the ion conductive rubber exceeds the above range, the ratio of the diene rubber and / or the ethylene propylene rubber decreases relatively, and the roller main body is good as the rubber described above May not be able to

On the other hand, by setting the blending ratio of the ion conductive rubber in the above range, the roller resistance value of the rubber roller can be adjusted to, for example, a range suitable as a transfer roller.
In addition, the roller body can also be provided with good properties as a rubber.
<Crosslinking component>
As the crosslinking component, a crosslinking agent for crosslinking the rubber and a crosslinking accelerator for promoting the crosslinking of the rubber by the crosslinking agent are preferably used in combination.

Among these, as a crosslinking agent, for example, a sulfur-based crosslinking agent, a thiourea-based crosslinking agent, a triazine derivative-based crosslinking agent, a peroxide-based crosslinking agent, various monomers and the like can be mentioned.
The crosslinking agent can be appropriately selected according to the type of rubber to be combined.
For example, in the case where the rubber is a combination of a diene rubber and / or EPDM each having a sulfur crosslinking property, and GECO, a sulfur crosslinking agent may be used as the crosslinking agent.

Also, for example, when the ion conductive rubber is ECO having no sulfur crosslinking property, as the crosslinking agent, a diene based rubber and / or a sulfur based crosslinking agent for crosslinking EPDM, and a thiourea for crosslinking ECO It may be used in combination with a crosslinking agent.
(Sulfur-based crosslinking agent)
Examples of sulfur-based crosslinking agents include sulfur such as powdered sulfur, oil-treated powdered sulfur, precipitated sulfur, colloidal sulfur, dispersible sulfur, and organic sulfur-containing compounds such as tetramethylthiuram disulfide and N, N-dithiobismorpholine. And the like, with sulfur being particularly preferred.

The blending ratio of sulfur is preferably 0.5 parts by mass or more, and 2 parts by mass or less, based on 100 parts by mass of the total amount of rubber, in consideration of imparting the above-described good characteristics as the rubber to the roller body. Is preferred.
In addition, for example, when using oil processing powder sulfur, dispersible sulfur etc. as sulfur, let the said mixing | blending ratio be a ratio of sulfur itself as an active ingredient contained in each.

Moreover, when using an organic sulfur-containing compound as a crosslinking agent, it is preferable to adjust the compounding ratio so that the ratio per total of 100 mass parts of rubbers of the sulfur contained in a molecule may become said range.
(Crosslinking accelerator)
Examples of the crosslinking accelerator for promoting the crosslinking of the rubber by the sulfur crosslinking agent include one or two of a thiazole accelerator, a thiuram accelerator, a sulfenamide accelerator, and a dithiocarbamate accelerator. There are more species.

Among these, it is preferable to use a thiuram-based accelerator and a thiazole-based accelerator in combination.
Examples of the thiuram-based accelerator include one or more species of tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, dipentamethylenethiuram tetrasulfide and the like.

Further, as a thiazole promoter, for example, 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, zinc salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2- (4 ') -Morpholino dithio) 1 type, or 2 or more types, such as benzothiazole, are mentioned.
Considering that the effect of promoting the crosslinking of the rubber by the sulfur-based crosslinking agent is sufficiently expressed in the combined use system of the two crosslinking accelerators, the compounding ratio of the thiuram-based accelerator is 100 parts by mass of the total amount of rubber. The content is preferably 0.3 parts by mass or more and 3 parts by mass or less.

Moreover, it is preferable that the compounding ratio of a thiazole type | system | group promoter is 0.3 mass part or more and 2 mass parts or less per 100 mass parts of total amounts of rubber | gum.
(Thiourea Crosslinker)
As the thiourea crosslinking agent, various thiourea compounds having a thiourea structure in the molecule and capable of functioning as an ECO crosslinking agent can be used.

Examples of thiourea crosslinking agents include ethylene thiourea, N, N′-diphenylthiourea, trimethylthiourea, and the like.
(C _n H _{2 n + 1} NH) ₂ C = S (2)
[In the formula, n represents an integer of 1 to 12. 1 or 2 types, such as thiourea represented by, and a tetramethyl thiourea, etc. are mentioned, Especially ethylene thiourea is preferable.

The compounding ratio of the thiourea-based crosslinking agent is preferably 0.3 parts by mass or more per 100 parts by mass of the total amount of rubber, considering that the roller body is provided with the above-described good characteristics as the rubber. It is preferably at most parts by weight.
(Crosslinking accelerator)
The thiourea crosslinking agent may be used in combination with various crosslinking accelerators that promote the crosslinking reaction of ECO by the thiourea crosslinking agent.

Examples of the crosslinking accelerator include one or more kinds of guanidine promoters such as 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide, etc. In particular, 1,3-di-o-tolyl guanidine is preferred.
The blending ratio of the crosslinking accelerator is preferably 0.3 parts by mass or more, and 1 part by mass or less, based on 100 parts by mass of the total amount of rubber, considering that the effect of promoting the crosslinking reaction is sufficiently expressed. Is preferred.

<Foaming component>
As a foaming component, various foaming agents which are decomposed by heating to generate a gas can be used. Moreover, you may combine the foaming adjuvant which acts to reduce the decomposition temperature of a foaming agent and to accelerate | stimulate the decomposition | disassembly.
(Foaming agent)
Examples of the foaming agent include one or more of azodicarbonamide (ADCA), 4,4′-oxybis (benzenesulfonylhydrazide) (OBSH), N, N-dinitrosopentamethylenetetramine (DPT), etc. It can be mentioned.

The proportion of the foaming agent is preferably 1 part by mass or more, and more preferably 5 parts by mass or less, per 100 parts by mass of the total amount of rubber.
(Foaming aid)
As the foaming aid, as described above, various foaming aids can be used to lower the decomposition temperature of the foaming agent to be combined and promote the decomposition thereof. For example, as the foaming aid to be combined with ADCA And urea (H ₂ NCO NH ₂ ) foaming aids.

Although the compounding ratio of the foaming auxiliary can be arbitrarily set according to the kind etc. of the foaming agent to combine, it is preferable that it is 1 mass part or more per 100 mass parts of total amounts of rubber, and it is preferable that it is 5 mass parts or less.
(Foaming component)
As the foaming component, it is particularly preferable to combine ADCA and a urea-based foaming aid, or to use OBSH alone.

<Others>
The rubber composition may further contain various additives as required.
As an additive, an acid acceptor, a filler, etc. are mentioned, for example.
Among these, as described above, the acid acceptor captures chlorine in chlorine-based gas generated from epichlorohydrin rubber or the like during crosslinking, and chlorine-based gas remains in the free state in the rubber roller, thereby causing crosslinking inhibition or the like. It functions to suppress the occurrence of contamination of the photosensitive body.

As the acid acceptor, various substances that act as acid acceptors can be used. Among them, hydrotalcites or magsarat having excellent dispersibility are preferable, and hydrotalcites are particularly preferable.
Further, when hydrotalcites and the like are used in combination with magnesium oxide and potassium oxide, it is possible to obtain a higher acid-accepting effect, and it is possible to more reliably prevent the contamination of the photoreceptor and the like.

The mixing ratio of the acid acceptor is preferably 0.2 parts by mass or more, particularly preferably 0.5 parts by mass or more, and more preferably 5 parts by mass or less, particularly preferably 2 parts by mass or less, per 100 parts by mass of the total amount of rubber. .
As a filler, 1 type (s) or 2 or more types, such as a zinc oxide, a silica, carbon black, a talc, a calcium carbonate, magnesium carbonate, aluminum hydroxide, etc. are mentioned, for example.

By blending the filler, the mechanical strength and the like of the rubber roller can be improved.
In addition, by using conductive carbon black as a filler, it is possible to impart electronic conductivity to the rubber roller.
HAF is preferable as the conductive carbon black.
Since HAF can be uniformly dispersed in the rubber composition, the rubber roller can be provided with as uniform electronic conductivity as possible.

The proportion of the conductive carbon black is preferably 5 parts by mass or more, and more preferably 20 parts by mass or less, per 100 parts by mass of the total amount of rubber.
Further, as additives, various additives such as a crosslinking assistant, an antidegradant, a scorch inhibitor, a plasticizer, a lubricant, a pigment, an antistatic agent, a flame retardant, a neutralizing agent, a nucleating agent, a co-crosslinking agent, etc. And may be blended at any ratio.

Rubber roller
FIG. 1 is a perspective view showing an example of the embodiment of the rubber roller of the present invention.
Referring to FIG. 1, the rubber roller 1 of this example comprises a porous roller body 2 formed in a single-layered tubular shape, which is made of a foam of a rubber composition containing the above-described components, and a roller body The shaft 4 is inserted into and fixed to the central through hole 3 of 2.

The shaft 4 is integrally formed of a highly conductive material, for example, a metal such as iron, aluminum, an aluminum alloy, stainless steel or the like.
The shaft 4 is, for example, electrically joined to the roller body 2 via a conductive adhesive and mechanically fixed, or one having an outer diameter larger than the inner diameter of the through hole 3. By press-fitting into 3, the roller body 2 is electrically joined and mechanically fixed.

Further, the shaft 4 may be electrically joined to the roller body 2 and mechanically fixed by using both methods in combination.
<Roller resistance value>
The roller resistance value R (Ω) of the rubber roller 1 can be set in a range suitable for the application according to the application of the rubber roller.

For example, in the case of a transfer roller, the roller resistance value R (Ω) measured by the following measurement method in a normal temperature and normal humidity environment at a temperature of 23 ± 1 ° C. and a relative humidity of 55 ± 1% It is preferable that it is 6.5 or more, and it is preferable that it is 7.5 or less.
(Measurement of roller resistance)
FIG. 2 is a view for explaining a method of measuring the roller resistance value of the rubber roller.

With reference to FIGS. 1 and 2, in this measurement method, an aluminum drum 6 that can be rotated at a constant rotational speed is prepared, and the roller resistance value is applied to the outer peripheral surface 7 of the prepared aluminum drum 6 from above. The outer peripheral surface 5 of the roller body 2 of the rubber roller 1 to be measured is brought into contact.
Further, a DC power supply 8 and a resistor 9 are connected in series between the shaft 4 of the rubber roller 1 and the aluminum drum 6 to constitute a measuring circuit 10.

The DC power supply 8 connects the (−) side to the shaft 4 and the (+) side to the resistor 9.
The resistance value r of the resistor 9 is 100 Ω.
Next, the aluminum drum 6 is rotated at 30 rpm in a state where the load F of 4.9 N ((500 gf) is applied to both ends of the shaft 4 and the roller body 2 is pressed against the aluminum drum 6.

Then, while continuing the rotation, a detection voltage V applied to the resistor 9 is measured 30 seconds after the application voltage E of DC 1000 V is applied from the DC power supply 8 between the rubber roller 1 and the aluminum drum 6.
From the measured detection voltage V and the applied voltage E (= 1000 V), the roller resistance value R of the rubber roller 1 is basically the formula (i ′):
R = r × E / V−r (i ′)
Determined by

However, since the term of -r in formula (i ') can be regarded as minute, in the present invention, formula (i):
R = r × E / V (i)
The roller resistance value of the rubber roller 1 is determined by the value obtained by
<Asker C hardness>
In the case of a transfer roller, the rubber hardness of the roller body 2 is preferably 20 ° or more, preferably 45 ° or less, as expressed by Asker C-type hardness.

If the Asker C-type hardness is less than this range, the strength of the roller body 2 may be insufficient, and it may be easy to cause sagging or the like.
On the other hand, when the Asker C-type hardness exceeds the above range, the roller body 2 may be too hard to obtain appropriate flexibility suitable for use as a transfer roller.
Asker-C hardness of the roller body 2, temperature 23 ± 1 ° C., relative humidity of 55 ± under 1% normal temperature and normal humidity environment, "Physical testing method for thermosetting polyurethane elastomer molded article" Japanese Industrial Standard JIS _{K7312 -1996} Type C hardness tester (for example, Asker rubber hardness meter C manufactured by Kobunshi Keiki Co., Ltd., etc.) in accordance with Japan Rubber Association Standard Standard SRIS 0101 “Physical test method of expanded rubber” incorporated in Appendix 2 of It shall be expressed by the value measured by the following method using.

(Measurement of Asker C hardness)
With the both ends of the shaft 4 inserted and fixed in the roller body 2 fixed to the support base, the pressing needle of the type C hardness tester is pressed against the central portion of the roller body 2 and 4.9 N (≒ Measure the Asker C hardness by applying a load of 500 gf).
<Manufacture of rubber roller>
In order to produce the rubber roller 1 of the present invention, first, a rubber composition comprising the above-described components is extruded into a tubular shape using an extrusion molding machine, and then cut into a predetermined length to obtain a vulcanized can. Internally pressurized with pressurized steam, heated to foam and crosslink.

Next, the foamed and crosslinked cylindrical body is heated and secondary-crosslinked using an oven or the like, cooled, and then polished to a predetermined outer diameter to form the roller body 2.
The shaft 4 can be inserted into the through hole 3 and fixed at any time after cutting of the cylindrical body and after polishing.
However, after cutting, it is preferable to perform secondary crosslinking and polishing in a state where the shaft 4 is inserted into the through hole 3 first.

Thereby, warpage, deformation or the like of the cylindrical body due to expansion and contraction at the time of secondary crosslinking can be suppressed.
Further, by polishing while rotating around the shaft 4, the workability of the polishing can be improved, and moreover, the deformation of the outer peripheral surface 5 can be suppressed.
As described above, the shaft 4 is inserted into the through hole 3 of the cylindrical body before secondary crosslinking via the conductive adhesive, in particular, the conductive thermosetting adhesive, and then secondary crosslinked. Alternatively, it may be pressed into the through hole 3 with an outer diameter larger than the inner diameter of the through hole 3.

In the former case, the thermosetting adhesive is cured simultaneously with the secondary crosslinking of the cylindrical body by heating in an oven, and the shaft 4 is electrically joined to the roller body 2 and mechanically It is fixed to
In the latter case, electrical connection and mechanical fixation are completed simultaneously with the press-in.
Further, as described above, the shaft 4 may be electrically joined to the roller body 2 and mechanically fixed by using both methods in combination.

<Cell diameter of foam cell>
The rubber roller 1 of the present invention manufactured through the above steps is, for example, when used as a transfer roller, the average of the foam cells exposed on the outer peripheral surface 5 of the roller main body 2 by polishing to improve the image quality of the formed image. The cell diameter is preferably 120 μm or less.
Further, the variation in cell diameter of the foamed cells exposed on the outer peripheral surface 5 of the roller body 2 is also small, and the largest cell diameter is preferably 150 μm or less.

In the present invention, these cell diameters are represented by values obtained by the following method.
(Measurement of cell diameter)
From the major diameter (μm) to the minor diameter (μm) of the largest 30 foam cells contained in the field of view observed at a magnification of 200 × with the microscope, the outer peripheral surface 5 of the roller main body 2 is represented by the formula (3) ):
Cell diameter (μm) = (long diameter + short diameter) / 2 (3)
The largest value among the cell diameters of the individual foam cells determined by the above is defined as the largest cell diameter.

In addition, an average value of 30 cell diameters is taken as an average cell diameter.
The rubber roller 1 according to the present invention is preferably used as a transfer roller as described above in an image forming apparatus using an electrophotographic method, such as a laser printer, an electrostatic copying machine, a plain paper facsimile machine, and a complex machine thereof. It can be used for
However, the rubber roller 1 of the present invention can also be used as, for example, a charging roller, a developing roller, a cleaning roller or the like.

<< Image forming device >>
The image forming apparatus of the present invention is characterized by incorporating the rubber roller 1 of the present invention.
As the image forming apparatus of the present invention, as described above, various image forming apparatuses utilizing electrophotography, such as a laser printer, an electrostatic copying machine, a plain paper facsimile apparatus, or a complex machine of these, are cited. Be

The present invention will be further described based on examples, comparative examples and conventional examples, but the configuration of the present invention is not necessarily limited to these examples and comparative examples.
Example 1
(Rubber composition)
As the rubber, 50 parts by mass of GECO (Nippon Zeon Co., Ltd. HYDRIN (registered trademark) T3108), and NBR (JSR Corporation JSR (registered trademark) N250SL, low nitrile NBR, acrylonitrile content 20%, non-oil) Exhibition] 50 parts by mass were blended.

  Then, while masticating 100 parts by mass of the total amount of both rubbers using a Banbury mixer, first, components other than the crosslinking component among the components shown in Table 1 below are added and kneaded, and the crosslinking component is further added and kneaded to be rubber The composition was prepared.

Each component in Table 1 is as follows. The parts by mass in Table 1 are parts by mass per 100 parts by mass of the total amount of rubber.
Zeolite: Natural zeolite (SP # 2300 manufactured by Nitto Shoko Kogyo Co., Ltd.)
Blowing agent: OBSH (Neocerbon (registered trademark) N # 1000 SW, manufactured by Eiwa Kasei Kogyo Co., Ltd.)
Filler: carbon black HAF (trade name SEAST 3 manufactured by Tokai Carbon Co., Ltd.)
Acid acceptor: Hydrotalcites [DHT-4A-2 manufactured by Kyowa Chemical Industry Co., Ltd.]
Crosslinking agent: powdered sulfur (manufactured by Tsurumi Chemical Industries, Ltd.)
Crosslinking accelerator DM: di-2-benzothiazolyl disulfide [Shandong Shanxian Chemical Co. Ltd. Product Name SUNSINE MBTS]
Crosslinking accelerator TS: tetramethylthiuram disulfide (Sunseller (registered trademark) TS manufactured by Sanshin Chemical Industry Co., Ltd.)
(Rubber roller)
The prepared rubber composition is supplied to an extrusion molding machine and extruded into a cylindrical shape with an outer diameter of 10 mm and an inner diameter of 3.0 mm, and then cut into a predetermined length to obtain a temporary shaft for crosslinking with an outer diameter of 2.2 mm. I wore it.

Then, the cylinder is pressurized and heated at 120 ° C. for 10 minutes, then 160 ° C. for 20 minutes in a vulcanizer, and the cylinder is foamed by the gas generated by the decomposition of the foaming agent and rubber Were crosslinked.
Next, this cylindrical body is re-mounted on the shaft 4 with an outer diameter of 5 mm coated with a conductive thermosetting adhesive on the outer peripheral surface, and heated in an oven at 160 ° C. for 60 minutes for secondary crosslinking. The thermosetting adhesive was cured to be electrically bonded to the shaft 4 and mechanically fixed.

Then, after shaping both ends of the cylindrical body, the outer peripheral surface 5 is traverse-grounded using a cylindrical grinder to finish the outer diameter to φ12.5 mm (tolerance ± 0.1 mm) to form the roller body 2 The rubber roller 1 was manufactured.
Example 2
A rubber composition was prepared in the same manner as in Example 1 except that the same amount of SBR (Sumitomo SBR 1502, manufactured by Sumitomo Chemical Co., Ltd., styrene content 23.5%, non-oil spread) was blended instead of NBR. , The rubber roller 1 was manufactured.

Example 3
In the same manner as in Example 1 except that the same amount of BR (JSR BR01 manufactured by JSR Corporation, high cis BR, cis-1,4 bond content 95%, non-oil spread) is blended instead of NBR. A rubber composition was prepared, and a rubber roller 1 was produced.
Example 4
The same as Example 1 except that the same amount of EPDM (Esprene EPDM 505A manufactured by Sumitomo Chemical Co., Ltd., ethylene content: 50%, diene content: 9.5%, non-oil spread) is blended instead of NBR. The rubber composition was prepared, and the rubber roller 1 was manufactured.

Comparative Examples 1 to 4
A rubber composition was prepared in the same manner as in Examples 1 to 4 except that the zeolite was not blended, and rubber roller 1 was manufactured.
Conventional Example 1
Silicone rubber compound [KE-551U manufactured by Shin-Etsu Chemical Co., Ltd.] 100 parts by mass, 5.0 parts by mass of zeolite, 2 parts by mass of organohydrogenpolysiloxane as a crosslinking agent, dimethyl-1, 1 as a foaming agent -A rubber composition was prepared by adding 5 parts by mass of azobis (1-cyclohexanecarboxylate) and chloroplatinic acid as a catalyst.

Then, a rubber roller was manufactured in the same manner as Example 1 except that the rubber composition was used.
The conventional example 1 corresponds to a reproduction of the first example of the patent document 2.
<Measurement and Evaluation of Cell Diameter of Foamed Cell>
The average cell diameter of the foamed cells exposed to the outer peripheral surface 5 and the largest cell diameter of the rubber roller 1 manufactured in the example, the comparative example, and the conventional example were determined by the method described above.

And those having an average cell diameter of 120 μm or less and the largest cell diameter of 150 μm or less are good (○), and the average cell diameter is 120 μm or less, but the largest cell diameter exceeds 150 μm, Those having an average cell diameter exceeding 120 μm were evaluated as defective (×).
<Evaluation of contamination>
(Test 1)
A state in which the roller main body 2 of the rubber roller 1 manufactured in the example, the comparative example, and the conventional example is brought into pressure contact with the photosensitive member taken out of the cartridge of the laser printer [HP LaserJet (registered trademark) P1606 dn made by HP Japan Inc.] The sample was allowed to stand in a high temperature and high humidity environment with a temperature of 40.degree. C. and a relative humidity of 90%.

The pressure load was 4.9 N (≒ 500 gf) per one side of the shaft 4 and 9.8 N (≒ 1 kgf) on both sides.
Then, after one week, the photoreceptor from which pressure contact was released was again incorporated into a cartridge and set in a laser printer, and 10 sheets of black solid images were continuously formed to confirm the presence or absence of an image defect.

(Test 2)
The roller main body 2 of the rubber roller 1 manufactured in the example, the comparative example, and the conventional example was allowed to stand in a high temperature and high humidity environment with a temperature of 40 ° C. and a relative humidity of 90%.
The pressure load was 4.9 N (≒ 500 gf) per one side of the shaft 4 and 9.8 N (≒ 1 kgf) on both sides.

Then, after one week, the surface of the aluminum foil released from pressure contact was observed with a microscope to confirm the presence or absence of a pressure contact mark.
(Evaluation)
Images in which no image defects were observed in the 10 images formed in Test 1 and no pressing marks were confirmed in Test 2 were evaluated as no contamination (good).

On the other hand, images in which an image failure was observed even in one of 10 images formed in test 1 and / or images in which a pressure welding mark was confirmed in test 2 were evaluated as contamination failure (x).
<Rubber hardness evaluation>
The Asker C-type hardness of the roller body 2 of the rubber roller 1 manufactured in the example, the comparative example, and the conventional example at a temperature of 23 ° C. and a relative humidity of 55% under a normal temperature and normal humidity environment according to the measuring method described above Measured.

Then, those having an Asker C-type hardness of not less than 20 ° and not more than 45 ° were evaluated as good (、), those less than 20 °, and those exceeding 45 ° were evaluated as defects (×).
<Evaluation of roller resistance value>
The roller resistance value R (Ω) of the rubber roller 1 manufactured in the example, comparative example, and conventional example in a normal temperature and normal humidity environment with a temperature of 23 ° C. and a relative humidity of 55% was measured according to the measurement method described above did.

And, when the measured roller resistance value R (Ω) is 6.5 or more and 7.5 or less in terms of common logarithm value log R, it is good (o), less than 6.5, and 7.5 or less. Those exceeding were evaluated as bad (x).
The above results are shown in Tables 2 and 3.

According to the results of Examples 1 to 4 and Comparative Examples 1 to 4 in Table 2 and Comparative Examples 1 to 4, by forming the roller main body with a rubber composition containing fine porous particles such as zeolite,
-It is possible to reduce the foaming of the rubber composition and to make the average cell diameter of the foamed cells smaller than the present condition, and to make the variation of the cell diameter smaller.
-It is possible to adsorb the component that is the source of contamination, and to suppress contamination of the member and the paper by the transfer of the component,
It has been found that when used as a transfer roller or the like, a rubber roller capable of forming an image with good image quality can be obtained.

However, according to the results of Examples 1 to 4 and Conventional Example 1, when the rubber is silicone rubber, the above effect can not be obtained even if the zeolite is blended, and the average of the foamed cells exposed on the outer peripheral surface of the roller body It has been found that it is impossible to reduce the cell diameter and the variation in the cell diameter and to suppress the contamination.
Example 5
(Rubber composition)
As rubber,
10 parts by mass of NBR (JSR (registered trademark) N250SL manufactured by JSR Corporation, low nitrile NBR, acrylonitrile content 20%, non-oil spread),
SBR (Sumitomo SBR 1502, manufactured by Sumitomo Chemical Co., Ltd., styrene content 23.5%, non-oil exhibition) 10 parts by mass,
10 parts by mass of BR [JSR BR01 manufactured by JSR Corporation, high cis BR, content of cis-1,4 bond 95%, non-oil spread],
-EPDM (Esprene EPDM 505A manufactured by Sumitomo Chemical Co., Ltd., ethylene content: 50%, diene content: 9.5%, non-oil spread) 10 parts by mass, and-GECO (Nippon Zeon Co., Ltd. HYDRIN (registered trademark) 60 parts by mass of a trademark T3108 was blended.

  Then, while masticating 100 parts by mass of the total amount of the above rubber using a Banbury mixer, first, components other than the crosslinking component among the components shown in Table 4 below are added and kneaded, and the crosslinking component is further added and kneaded to be rubber The composition was prepared.

Each ingredient in Table 4 is as follows. The parts by mass in Table 1 are parts by mass per 100 parts by mass of the total amount of rubber.
Zeolite: Natural zeolite (SP # 2300 manufactured by Nitto Shoko Kogyo Co., Ltd.)
Blowing agent: ADCA (trade name Binihall AC # 3 manufactured by Eiwa Kasei Kogyo Co., Ltd.)
Foaming aid: Urea-based foaming aid (trade name Cell Paste 101, manufactured by Eiwa Kasei Kogyo Co., Ltd.)
Acid acceptor: Hydrotalcites [DHT-4A-2 manufactured by Kyowa Chemical Industry Co., Ltd.]
Crosslinking agent: powdered sulfur (manufactured by Tsurumi Chemical Industries, Ltd.)
Crosslinking accelerator DM: di-2-benzothiazolyl disulfide [Shandong Shanxian Chemical Co. Ltd. Product Name SUNSINE MBTS]
Crosslinking accelerator TS: tetramethylthiuram disulfide (Sunseller (registered trademark) TS manufactured by Sanshin Chemical Industry Co., Ltd.)
(Rubber roller)
The prepared rubber composition is supplied to an extrusion molding machine and extruded into a cylinder having an outer diameter of 15 mm and an inner diameter of 4.5 mm, and then cut into a predetermined length to obtain a temporary shaft for crosslinking of 3.5 mm outer diameter. I wore it.

Then, the cylinder is pressurized and heated at 120 ° C. for 10 minutes, then 160 ° C. for 20 minutes in a vulcanizer, and the cylinder is foamed by the gas generated by the decomposition of the foaming agent and rubber Were crosslinked.
Next, this cylindrical body is remounted on the shaft 4 with an outer diameter of φ 6 mm coated with a conductive thermosetting adhesive on the outer peripheral surface, and heated in an oven at 160 ° C. for 60 minutes for secondary crosslinking. The thermosetting adhesive was cured to be electrically bonded to the shaft 4 and mechanically fixed.

Then, after shaping both ends of the cylindrical body, the outer peripheral surface 5 is traverse-grounded using a cylindrical grinder to finish the outer diameter to φ13 mm (tolerance ± 0.1 mm) to form the roller main body 2; The rubber roller 1 was manufactured.
Example 6
A rubber composition is prepared in the same manner as in Example 5 except that the same amount of activated carbon [Klarecol (registered trademark) PK-D manufactured by Kuraray Co., Ltd.] is blended in place of zeolite, and rubber roller 1 is manufactured. did.

Example 7
In place of zeolite, the same amount of diatomaceous earth [Topco (registered trademark) No. 1 made by Showa Chemical Industry Co., Ltd.] is used. A rubber composition was prepared in the same manner as in Example 5 except that 54] was compounded, to produce a rubber roller 1.
Comparative Example 5
A rubber composition was prepared in the same manner as in Example 5 except that the zeolite was not blended, and a rubber roller 1 was produced.

Example 8, Comparative Example 6
A rubber composition was prepared in the same manner as Example 5, except that the blending ratio of zeolite was 35.0 parts by mass (Example 8) and 40.0 parts by mass (Comparative Example 6) per 100 parts by mass of the total amount of rubber. The rubber roller 1 was prepared.
Example 9, Comparative Example 7
A rubber composition was prepared in the same manner as Example 6, except that the blending ratio of activated carbon was 20.0 parts by mass (Example 9) and 25.0 parts by mass (Comparative Example 7) per 100 parts by mass of the total amount of rubber. The rubber roller 1 was prepared.

Example 10, Comparative Example 8
A rubber composition was prepared in the same manner as in Example 7 except that the blending ratio of diatomaceous earth was 35.0 parts by mass (Example 10) and 40.0 parts by mass (Comparative Example 8) per 100 parts by mass of the total amount of rubber. The rubber roller 1 was manufactured.
Each evaluation mentioned above was implemented about the rubber roller 1 manufactured by the said Example and comparative example. The results are shown in Tables 5 and 6.

From the results of Examples 5 to 10 of Table 5 and Table 6 and Comparative Example 5, the rubber composition containing at least one kind of microporous particles selected from the group consisting of zeolite, activated carbon and diatomaceous earth Also, by forming the rubber, it is possible to reduce the foaming of the rubber composition and to make the average cell diameter of the foamed cells smaller than the present condition, and to reduce the variation of the cell diameter,
-It is possible to adsorb the component that is the source of contamination, and to suppress contamination of the member and the paper by the transfer of the component,
It has been found that when used as a transfer roller or the like, a rubber roller capable of forming an image with good image quality can be obtained.

However, according to the results of Examples 5 and 8 and Comparative Example 6, in the system using zeolite as the fine porous particles, the rubber hardness of the roller body and the roller resistance value are suitable as a transfer roller etc. while maintaining the above effects. It was found that it is necessary to set the blending ratio of the zeolite to 35 parts by mass or less per 100 parts by mass of the total amount of rubber, in order to obtain the above range.
Further, according to the results of Examples 6 and 9 and Comparative Example 7, in the system using activated carbon as the fine porous particles, the rubber hardness of the roller main body and the roller resistance value are suitable as a transfer roller etc. while maintaining the above effects. It was found that it is necessary to set the blending ratio of the activated carbon to 20 parts by mass or less per 100 parts by mass of the total amount of rubber, in order to set the above range.

  Furthermore, according to the results of Examples 7 and 10 and Comparative Example 8, in the system using diatomaceous earth as the fine porous particles, the rubber hardness and roller resistance value of the roller main body are used as a transfer roller etc. while maintaining the above effect. It turned out that it is necessary to make the compounding ratio of the said diatomaceous earth into 35 mass parts or less per 100 mass parts of total amounts of rubber, in order to set it as a suitable range.

1 rubber roller 2 roller body 3 through hole 4 shaft 5 outer peripheral surface 6 aluminum drum 7 outer peripheral surface 8 DC power supply 9 resistance 10 measurement circuit F load V detection voltage

Claims (4)

A rubber composition for forming a porous body used in an image forming apparatus utilizing electrophotography,
A rubber comprising an ion conductive rubber, and at least one member selected from the group consisting of a diene rubber and an ethylene propylene rubber,
A crosslinking component for crosslinking the rubber,
The three components of the present invention include a foaming component for foaming the rubber, and at least one fine porous particle selected from the group consisting of zeolite, activated carbon, and diatomaceous earth, per 100 parts by mass of the total amount of the rubber. The blending ratio P of the total of the fine porous particles is represented by the formula (1)
P ≦ Z × 35 + C × 20 + D × 35 (1)
[In the formula, Z represents zeolite, C represents activated carbon, D represents diatomaceous earth, and the mass ratio of each of the three types of fine porous particles is 1]. ]
Satisfy rubber composition.   The rubber composition according to claim 1, wherein the rubber contains only an ion conductive rubber and at least one selected from the group consisting of a diene rubber and an ethylene propylene rubber.   A rubber roller comprising a porous roller body comprising the rubber composition according to claim 1 or 2.   An image forming apparatus comprising the rubber roller according to claim 3.

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