JP2022165543A - Rubber composition for transfer roller and transfer roller - Google Patents

Abstract

To provide a rubber composition for transfer roller which may form a transfer roller in which the variations of a roller resistance value due to a difference in a use environment and the rise of the roller resistance value in the continuous electric conduction are small, the roller resistance value is stable and which can continuously form images with the excellent image quality, and provide a transfer roller including a roller body formed by using the rubber composition for transfer roller.SOLUTION: A rubber composition for transfer roller includes NBR and GECO. The GECO jointly uses only two kinds of GECO (I) whose AGE content is 0.1 to 4.0 mol% and GECO (II) whose AGE content is 4.5 to 6.0 mol%. A transfer roller 1 includes a porous roller body 2 made of a cross-linked material of the rubber composition for transfer roller.SELECTED DRAWING: Figure 1

Description

The present invention relates to a rubber composition for forming a transfer roller for use in an electrophotographic image forming apparatus such as a laser printer, an electrostatic copier, a plain paper facsimile machine, or a multifunction machine of these, and a rubber composition using the rubber composition. The present invention relates to a transfer roller including a roller body formed by the method.

In an image forming apparatus, a roller body of a transfer roller used for transferring a toner image formed on a photoreceptor to a surface of paper is made of rubber and a crosslinked rubber composition containing a crosslinking component for crosslinking the rubber. may be formed porous by (See Patent Document 1, etc.).

JP 2016-142793 A JP 2014-51574 A

In Patent Document 1, acrylonitrile-butadiene rubber and an epichlorohydrin-ethylene oxide-allylglycidyl ether terpolymer, which is an ion-conductive rubber, are used in combination as the rubber that forms the base of the roller body, so that the transfer roller is ion-conductive. endowed with sex.
However, according to the study of the inventor, the transfer roller imparted with ionic conductivity by the ionic conductive rubber has a problem that the roller resistance value fluctuates greatly depending on the difference in use environment, that is, the difference in temperature and humidity.

In addition, the roller resistance value of the transfer roller greatly fluctuates due to differences in locations where the image forming apparatus incorporating the transfer roller is installed, and changes in climate and weather even in the same location, resulting in deterioration of the formed image such as image density. image quality may be affected.
If a methacrylic acid ester is added to the rubber composition for the transfer roller, the difference in roller resistance due to the difference in usage environment can be reduced. There is a problem that it is easy to cause contamination such as.

Therefore, in Patent Document 2, it is considered to select and use a (meth)acrylic acid ester compound having a specific structure.
Such a specific (meth)acrylic acid ester compound is excellent in the effect of reducing the difference in roller resistance value due to the difference in usage environment, and even if the amount is reduced, the same effect as the conventional one can be obtained. It is expected that the accompanying contamination of the photoreceptor and the like can be suppressed.

However, even with such a specific (meth)acrylic acid ester compound, when the transfer roller is continuously energized for a relatively long period of time, it still bleeds onto the outer peripheral surface of the roller body, resulting in exposure to light. It may cause contamination of the body etc.
In addition, even if it does not bleed, the (meth)acrylic acid ester compound may move in the roller body due to energization and cause uneven distribution, which may increase the roller resistance of the transfer roller.

It is an object of the present invention to provide a stable roller resistance with little variation in roller resistance due to differences in usage environment and a small increase in roller resistance during continuous energization, and to enable continuous formation of high-quality images. An object of the present invention is to provide a rubber composition for a transfer roller that can form a transfer roller.
Another object of the present invention is to provide a transfer roller including a roller body formed using the rubber composition for a transfer roller.

The present invention comprises a rubber comprising acrylonitrile butadiene rubber and an epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer, and a cross-linking component for cross-linking said rubber, and said epichlorohydrin-ethylene oxide-allyl glycidyl ether ternary. The copolymer is
(I) an epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer having an allyl glycidyl ether content of 0.1 mol% or more and 4.0 mol% or less; and
(II) an epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer having an allyl glycidyl ether content of 4.5 mol% or more and 6.0 mol% or less;
are two types of rubber compositions for transfer rollers.

The present invention also provides a transfer roller including a porous roller main body made of a crosslinked product of the rubber composition for a transfer roller of the present invention.

According to the present invention, fluctuations in the roller resistance value due to differences in usage environment and increases in the roller resistance value during continuous energization are small, and the roller resistance value is stable, so that images with good image quality can be continuously formed. A rubber composition for a transfer roller can be provided that can form a transfer roller.
Further, according to the present invention, it is possible to provide a transfer roller including a roller body formed using the rubber composition for a transfer roller.

1 is a perspective view showing an example of an embodiment of a transfer roller of the present invention; FIG. FIG. 4 is a diagram illustrating a method of measuring a roller resistance value of a transfer roller;

<<Rubber composition for transfer roller>>
The rubber composition for a transfer roller of the present invention comprises, as described above, acrylonitrile-butadiene rubber (NBR), rubber containing epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (GECO), and rubber for cross-linking rubber. comprising a cross-linking component, and GECO comprising:
(I) GECO having an allyl glycidyl ether (AGE) content of 0.1 mol % or more and 4.0 mol % or less (hereinafter sometimes abbreviated as "GECO (I)"); 〕,and
(II) GECO having an allyl glycidyl ether (AGE) content of 4.5 mol % or more and 6.0 mol % or less (hereinafter sometimes abbreviated as "GECO (II)"); ],
Only two types of [GECO (I) and GECO (II) include cases where two or more types are used in combination. Same below. ].

According to the present invention, ion conductivity can be imparted to the transfer roller by using GECO, which is an ion conductive rubber, as the rubber as described above.
In addition, by using NBR, which is a diene rubber, together with GECO, it is possible to impart good workability to the rubber composition for transfer rollers and improve the mechanical strength and durability of the roller body. .

In addition, by using NBR together, the roller body can be imparted with good properties as rubber, that is, properties such as flexibility, low compression set and resistance to settling.
Moreover, by using only two types of GECO, GECO (I) and GECO (II), which differ in AGE content, the roller resistance value is stable, and a transfer roller that can continue to form images with good image quality is formed. You can also

That is, by using GECO (II) having an AGE content of 4.5 to 6.0 mol % as GECO, it is possible to suppress fluctuations in roller resistance value due to differences in usage environments.
However, when only GECO (II) is used, there is a tendency for the roller resistance value to increase during continuous energization.
In addition, the roller body may become hard and unsuitable as a transfer roller for an image forming apparatus, particularly for forming color images.

On the other hand, by using GECO (I) with an AGE content of 0.1 to 4.0 mol % together with GECO (II), the roller resistance value during continuous energization increases and the roller body becomes hard. You can prevent it from happening.
Therefore, by using these two types of GECO together, fluctuations in the roller resistance value due to differences in the usage environment and increases in the roller resistance value during continuous energization are small, and the roller resistance value is stable, resulting in good image quality. It is possible to form a transfer roller that can continue to form a

These facts are also apparent from the results of Examples and Comparative Examples, which will be described later.
In Examples 9 and 10 of Patent Document 1, two types of GECO, Epichromer (registered trademark) CG102 manufactured by Osaka Soda Co., Ltd. and EPION (registered trademark) 301 manufactured by the same company, are used in combination. The AGE content is outside the limits of the invention mentioned above.

Specifically, the AGE content of epichromer CG102 is 4.0, the AGE content of epion 301 is 4.1, and does not contain GECO (II). The variation in the roller resistance value becomes large due to the difference in .
Therefore, Examples 9 and 10 of Patent Document 1 merely correspond to the prior art of the present invention, and do not teach or suggest the present invention.

<GECO (I)>
GECO (I) is a terpolymer of epichlorohydrin (EP), ethylene oxide (EO), and allyl glycidyl ether (AGE) with an AGE content of 0.1 mol% or more and 4.0 mol% Any of the following GECO variations are available.
GECO (I) is not only a copolymer in a narrow sense obtained by copolymerizing the above three monomers, but also an epichlorohydrin-ethylene oxide binary copolymer (ECO) with allyl glycidyl ether. Modified modified products can also be used.
Allyl glycidyl ether itself functions as a side chain to secure free volume, thereby suppressing crystallization of ethylene oxide and reducing the roller resistance of the transfer roller.

However, if the AGE content is less than the above range, such action cannot be sufficiently obtained, and the roller resistance value of the transfer roller may not be sufficiently lowered to the range suitable for the transfer roller.
On the other hand, GECO with an AGE content exceeding the above range, even when used in combination with GECO (II), suppresses the increase in roller resistance during continuous energization and the hardening of the roller body, as described above. Can not do it.

On the other hand, by selecting GECO(I) whose AGE content is within the above range and using it together with GECO(II), the resistance of the roller during continuous energization increases and the roller body does not become hard. can be suppressed.
It is also possible to give the transfer roller a roller resistance value suitable for the transfer roller.

Specific examples of GECO (I) having an AGE content within the above range include, but are not limited to, the following various GECOs.
Osaka Soda Co., Ltd. Epichroma CG102 [EO / EP / AGE = 56.0 / 40.0 / 4.0 (molar ratio), Mooney viscosity ML (1 + 4) 100 ° C.: 55], CG104 [EO / EP / AGE = 35.5/62.0/2.5 (molar ratio), Mooney viscosity ML (1+4) 100°C: 60], CG105 [EO/EP/AGE = 48.0/48.0/4.0 ( Molar ratio), Mooney viscosity ML (1 + 4) 100 ° C.: 65], CG107 [EO / EP / AGE = 41.0 / 56.0 / 3.0 (molar ratio), Mooney viscosity ML (1 + 4) 100 ° C.: 65 ].

HYDRIN (registered trademark) T3108 [EO/EP/AGE=64.0/33.2/2.8 (molar ratio), Mooney viscosity ML (1+4) 100° C.: 47] manufactured by Zeon Corporation.
However, it is preferable to select and use GECO (I) having an AGE content within the above range and an ethylene oxide (EO) content of 30 mol % or more and 60 mol % or less.

Ethylene oxide works to lower the roller resistance of the transfer roller.
However, if the EO content is less than this range, such function cannot be sufficiently obtained, and the roller resistance value of the transfer roller may not be sufficiently reduced to a range suitable for the transfer roller.
On the other hand, if the EO content exceeds the above range, crystallization of ethylene oxide occurs, hindering the segmental motion of the molecular chain. may contaminate the photoreceptor or the like.

Considering the improvement of kneadability with GECO (II) and NBR, GECO (I) satisfies the above ranges for AGE content and EO content, and Mooney viscosity ML (1+4) 100°C It is more preferable to select and use one with a value of 50 or more.
GECO(I) satisfying these conditions include, in particular, the epichromers CG102, CG104 and CG105.
One or more of these GECO (I) can be used.

<GECO (II)>
GECO (II) is a terpolymer of epichlorohydrin (EP), ethylene oxide (EO), and allyl glycidyl ether (AGE) with an AGE content of 4.5 mol% or more and 6.0 mol% Any of the following GECO variations are available.

As GECO (II), not only copolymers in the narrow sense obtained by copolymerizing the above three kinds of monomers, but also modified products obtained by modifying ECO with allyl glycidyl ether can be used.
Allyl glycidyl ether functions as a cross-linking point during cross-linking of GECO.
Therefore, if the AGE content exceeds the above range, the crosslink density of GECO becomes too high, hindering the segmental movement of the molecular chains, which tends to increase the roller resistance of the transfer roller.

On the other hand, GECO having an AGE content below the above range cannot suppress fluctuations in roller resistance due to differences in use environment, as described above, even when used in combination with GECO (I).
On the other hand, by selecting GECO (II) having an AGE content within the above range and using it together with GECO (I), the transfer roller can A roller resistance value suitable for the transfer roller can be given.

As GECO (II), in consideration of improving the kneadability with GECO (I) and NBR, the AGE content satisfies the above range and the Mooney viscosity ML (1 + 4) 100 ° C. is 50 or more. It is even more preferable to select and use one.
Specific examples of GECO (II) satisfying these conditions include, but are not limited to, HYDRIN T3106 [EO/EP/AGE=56.0/39.3/4.7 manufactured by Nippon Zeon Co., Ltd. (molar ratio), Mooney viscosity ML (1+4) 100° C.:60] and the like.
One or more of these GECO (II) can be used.

<NBR>
As the NBR, any of various crosslinkable NBRs synthesized by copolymerizing acrylonitrile and butadiene by various polymerization methods such as emulsion polymerization can be used.

The NBR includes low nitrile NBR with an acrylonitrile content of 24% or less, medium nitrile NBR with an acrylonitrile content of 25 to 30%, medium and high nitrile NBR with an acrylonitrile content of 31 to 35%, high nitrile NBR with an acrylonitrile content of 36 to 42%, and 43% or more. Any very high nitrile NBR is available.
There are two types of NBR: an oil-extended type in which extender oil is added to adjust flexibility, and a non-oil-extended type in which extension oil is not added. It is preferable to use non-oil-extended NBR that does not contain extender oil that can be a bleeding substance.
One or more of these NBRs can be used.

<Other rubbers>
As the rubber, if necessary, diene rubber other than NBR such as styrene-butadiene rubber (SBR), chloroprene rubber (CR), acrylic rubber (ACM), or ethylene-α-olefin-nonconjugated A polyene copolymer rubber or the like may be used together.

In particular, when ethylene-α-olefin-non-conjugated polyene copolymer rubber is used together, the ozone resistance of the roller body is improved, making it suitable for use in image forming apparatuses that employ a charging method using corona discharge, which is particularly susceptible to the generation of ozone. Rollers can be formed.
As the ethylene-α-olefin-nonconjugated polyene copolymer rubber, ethylene-propylene-diene copolymer rubber (EPDM), which is excellent in the effect of improving ozone resistance and is highly versatile, is particularly preferable.

(EPDM)
As the EPDM, any of various EPDMs in which a double bond is introduced into the main chain by adding a small amount of a third component (diene component) to ethylene and propylene can be used.
As EPDM, various products are provided that differ in the type and amount of the third component.
Typical third components include ethylidene norbornene (ENB), 1,4-hexadiene (1,4-HD), dicyclopentadiene (DCP) and the like.

A Ziegler catalyst is generally used as the polymerization catalyst.
EPDM includes an oil-extended type in which extender oil is added to adjust flexibility, and a non-oil-extended type in which no extender oil is added. It is preferable to use a non-oil-extended EPDM that does not contain an extender oil that can be a bleeding substance.
One or more of these EPDMs can be used.

<rubber ratio>
The ratio PA of GECO (II) having an AGE content of 4.5 to 6.0 mol% per 100 parts by mass of GECO (I) having an AGE content of 0.1 to 4.0 mol% is 30 parts by mass. Above all, it is preferably 40 parts by mass or more, particularly preferably 50 parts by mass or more, and preferably 95 parts by mass or less, particularly preferably 80 parts by mass or less.

If the ratio PA of GECO(II) is less than this range, it may not be possible to suppress fluctuations in the roller resistance due to differences in use environment.
On the other hand, if the ratio PA of GECO(II) is higher than the above range, the ratio of GECO(I) becomes relatively small, and it may not be possible to suppress an increase in the roller resistance value during continuous energization.
On the other hand, by setting the ratio PA of GECO (II) per 100 parts by mass of GECO (I) within the above range, fluctuations in the roller resistance value due to differences in the use environment and an increase in the roller resistance value during continuous energization can be reduced to further stabilize the roller resistance value.

Further, the total ratio PB of GECO (I) and GECO (II) in 100 parts by mass of the total amount of rubber is preferably 30 parts by mass or more, particularly 35 parts by mass or more, and 75 parts by mass or less, particularly It is preferably 70 parts by mass or less.
If the total ratio PB of the two GECOs, which are ion-conductive rubbers, is less than this range, the transfer roller may not be provided with a sufficient roller resistance suitable for the transfer roller.

On the other hand, if the total ratio PB of both GECOs is greater than the above range, the roller resistance value may fluctuate greatly due to the difference in usage environment even though the two types of GECOs are used together.
In addition, the proportion of NBR is relatively low, and there are cases where the roller body of the transfer roller cannot be imparted with good properties as a rubber.

On the other hand, by setting the total ratio PB of the two types of GECO within the above range, it is possible to reduce fluctuations in the roller resistance value due to differences in the usage environment while imparting good rubber characteristics to the roller body. Therefore, the roller resistance value can be stabilized.
Also, the transfer roller can be provided with a sufficient roller resistance value suitable for the transfer roller.

The proportion of NBR is the balance of the two GECOs when no other rubber such as EPDM is blended.
That is, the proportion of NBR is preferably 25 parts by mass or more, particularly preferably 30 parts by mass or more, and preferably 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.

When EPDM is blended as another rubber, the proportion of the EPDM is 5 parts by mass or more, particularly 10 parts by mass, in 100 parts by mass of the total rubber in order to obtain the above-mentioned effect of improving the ozone resistance. It is preferably 30 parts by mass or less, particularly preferably 20 parts by mass or less.

When EPDM is used together, the ratio of NBR may be the balance of the two types of GECO and EPDM.
That is, the proportion of NBR is preferably 5 parts by mass or more, particularly preferably 15 parts by mass or more, and preferably 65 parts by mass or less, particularly preferably 50 parts by mass or less, in 100 parts by mass of the total amount of rubber.

<Crosslinking component>
Cross-linking components for cross-linking rubber include cross-linking agents and cross-linking accelerators.
(crosslinking agent)
Examples of cross-linking agents include sulfur-based cross-linking agents, peroxide-based cross-linking agents, etc., and sulfur-based cross-linking agents are particularly preferred.
Examples of sulfur-based cross-linking agents include sulfur such as powdered sulfur, powdered sulfur containing oil, precipitated sulfur, colloidal sulfur, and dispersible sulfur, and organic sulfur-containing compounds such as tetramethylthiuram disulfide and N,N-dithiobismorpholine. sulfur is particularly preferred.

Although the proportion of sulfur can be set arbitrarily, it is preferably 0.5 parts by mass or more, particularly 1 part by mass or more, and 2.5 parts by mass or less, particularly 2 parts by mass or less per 100 parts by mass of the total amount of rubber. is preferred.
If the proportion of sulfur is less than this range, the speed of crosslinking of the rubber composition for transfer rollers as a whole becomes slow, and the time required for crosslinking increases, which may reduce the productivity of transfer rollers.

Further, when the sulfur content exceeds the above range, the compression set after crosslinking may become large, or excessive sulfur may bloom on the outer peripheral surface of the roller body.
In the case of using, for example, oil-containing powdered sulfur, dispersible sulfur, etc. as sulfur, the above ratio is the ratio of sulfur itself as an active ingredient contained therein.
Further, when an organic sulfur-containing compound is used as a cross-linking agent, it is preferable to adjust the ratio so that the ratio of sulfur contained in the molecule per 100 parts by mass of the total amount of rubber is within the above range.

(Crosslinking accelerator)
Examples of cross-linking accelerators include inorganic accelerators such as slaked lime, magnesia (MgO) and litharge (PbO), and one or more of the following organic accelerators.
Guanidine accelerators such as 1,3-di-o-tolylguanidine, 1,3-diphenylguanidine, 1-o-tolylbiguanide, and dicatechol borate di-o-tolylguanidine salt.

thiazole accelerators such as 2-mercaptobenzothiazole and di-2-benzothiazolyl disulfide;
Sulfenamide accelerators such as N-tert-butyl-2-benzothiazolylsulfenamide and N-cyclohexyl-2-benzothiazolylsulfenamide.
thiuram accelerators such as tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, dipentamethylenethiuram tetrasulfide;

dithiocarbamate accelerators such as zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, and zinc dibutyldithiocarbamate;
thiourea accelerators such as N,N'-diphenylthiourea, trimethylthiourea, N,N'-diethylthiourea;
The ratio of the cross-linking accelerator can be arbitrarily set depending on the type thereof, but usually it is preferably 0.1 parts by mass or more, particularly 0.2 parts by mass or more, per 100 parts by mass of the total rubber. It is preferably 5 parts by mass or less, particularly 2 parts by mass or less.

<Foam component>
It is preferable that the roller body of the transfer roller is made porous by a crosslinked product of the rubber composition for the transfer roller.
In order to make the roller body porous, a foaming component may be added to the rubber composition for the transfer roller so that the rubber is crosslinked and foamed.

As the foaming component, various foaming agents that are decomposed by heating to generate gas can be used.
Also, a foaming aid may be combined that functions to lower the decomposition temperature of the foaming agent and promote its decomposition.

(foaming agent)
Examples of foaming agents include one or more of azodicarbonamide (ADCA), 4,4′-oxybis(benzenesulfonylhydrazide) (OBSH), N,N-dinitrosopentamethylenetetramine (DPT), and the like. mentioned. ADCA is particularly preferred.
The proportion of the foaming agent is preferably 1 part by mass or more, particularly preferably 3 parts by mass or more, and preferably 7 parts by mass or less, particularly preferably 5 parts by mass or less per 100 parts by mass of the total amount of rubber.

(foaming aid)
As the foaming aid, various foaming aids can be used that function to lower the decomposition temperature of the combined foaming agent and promote its decomposition, as described above.
For example, foaming aids combined with ADCA include urea (H ₂ NCONH ₂ )-based foaming aids.
The proportion of the foaming aid can be arbitrarily set according to the type of foaming agent to be combined, etc., but it is preferably 1 part by mass or more, particularly preferably 2 parts by mass or more, and 5 parts by mass or less, per 100 parts by mass of the total amount of rubber. In particular, it is preferably 3 parts by mass or less.

<others>
If necessary, various additives may be added to the rubber composition for the transfer roller.
Additives include, for example, acid acceptors, fillers, deterioration inhibitors, cross-linking aids, plasticizers, and the like.

(acid acceptor)
Of the above, the acid acceptor captures the chlorine in the chlorine-based gas generated by GECO during cross-linking, and the chlorine-based gas remains in the roller body in a free state, thereby inhibiting cross-linking and contamination of the photoreceptor. It functions to suppress the occurrence of such things as

As the acid acceptor, various substances that act as an acid acceptor can be used. Among them, hydrotalcites or magsalat, which are excellent in dispersibility, are preferred, and hydrotalcites are particularly preferred.
Further, when hydrotalcite or the like is used in combination with magnesium oxide or potassium oxide, a higher acid-accepting effect can be obtained, and contamination of the photoreceptor or the like can be more reliably prevented.
The proportion of the acid acceptor is preferably 0.1 parts by mass or more, particularly 0.5 parts by mass or more, and 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.

(filler)
The filler functions to improve the mechanical strength and the like of the roller body, and to lower the compounding unit cost of rubber compounding without affecting the properties of the roller body.

Examples of fillers include one or more of zinc oxide, silica, carbon black, talc, calcium carbonate, clay, magnesium carbonate, aluminum hydroxide and the like.
In particular, it is preferable to use one or more of talc, calcium carbonate, clay, magnesium carbonate, aluminum hydroxide and the like in order to reduce the unit price of rubber compounding without affecting the properties of the roller body.

The proportion of the filler is preferably 3 parts by weight or more, especially 7 parts by weight or more, and preferably 15 parts by weight or less, especially 12 parts by weight or less, per 100 parts by weight of the total amount of rubber.
Further, by using conductive carbon black as a filler, it is possible to impart electronic conductivity to the roller body.
HAF is preferred as the conductive carbon black.

Since HAF can be uniformly dispersed in the rubber composition for the transfer roller, it is possible to provide the roller body with as uniform electronic conductivity as possible.
The proportion of the conductive carbon black is preferably 1 part by weight or more, particularly 3 parts by weight or more, and preferably 10 parts by weight or less, particularly 7 parts by weight or less, per 100 parts by weight of the total rubber.

(degradation inhibitor)
Anti-deterioration agents include various anti-aging agents and antioxidants.
Among them, the anti-aging agent reduces the dependence of the roller resistance value of the transfer roller on the environment and suppresses an increase in the roller resistance value during continuous energization.
Anti-aging agents include, for example, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine and zinc salt of 2-mercaptobenzimidazole.
The proportion of the anti-aging agent is preferably 0.5 parts by mass or more, particularly preferably 1 part by mass or more, and preferably 5 parts by mass or less, particularly 4 parts by mass or less, per 100 parts by mass of the total rubber. preferable.

(crosslinking aid)
Examples of cross-linking aids include metal compounds such as zinc oxide; fatty acids such as stearic acid, oleic acid and cottonseed fatty acid; and one or more of conventionally known cross-linking aids.
The proportion of the cross-linking coagent is preferably 0.1 parts by mass or more, particularly preferably 0.5 parts by mass or more, and 8 parts by mass or less, particularly 6 parts by mass or less per 100 parts by mass of the total amount of rubber. is preferred.

As additives, various additives such as waxes, colorants, tackifiers, anti-scorch agents, lubricants, pigments, antistatic agents, flame retardants, neutralizers, nucleating agents, and co-crosslinking agents may be used. may be blended at a ratio of
The rubber composition for the transfer roller can be prepared, for example, by first kneading each component other than the cross-linking component among the above components using a kneader, Banbury mixer, etc., and then adding the cross-linking component and kneading.

《Transfer roller》
FIG. 1 is a perspective view showing an example of an embodiment of a transfer roller of the invention.
Referring to FIG. 1, the transfer roller 1 of this example is a porous single-layer cylinder formed by cross-linking and foaming (cross-linked and foaming) of the transfer roller rubber composition containing the above components. It includes a roller body 2 which is shaped into a shape.
A shaft 4 is inserted through and fixed to a through hole 3 in the center of the roller body 2 .
The shaft 4 is integrally formed of a highly conductive material such as metal such as iron, aluminum, aluminum alloy, and stainless steel.

Shaft 4 is electrically connected and mechanically fixed to roller body 2 via, for example, a conductive adhesive, or has an outer diameter larger than the inner diameter of through hole 3 . By press-fitting into the roller body 2, it is electrically connected to the roller body 2 and mechanically fixed.
Alternatively, both methods may be used together to electrically connect the shaft 4 to the roller body 2 and mechanically fix them.

In order to manufacture the transfer roller 1, first, the prepared rubber composition for the transfer roller is extruded into a cylindrical shape using an extruder, then cut into a predetermined length, and pressurized and heated in a vulcanization can. Then, the rubber is crosslinked and foamed.
Next, the crosslinked and foamed cylindrical body is heated using an oven or the like to cause secondary crosslinking, and after cooling, the outer peripheral surface 5 of the roller body 2 is polished so as to have a predetermined outer diameter.

Various polishing methods such as dry traverse polishing can be used as the polishing method.
The shaft 4 can be fixed by inserting it into the through hole 3 at any time from after cutting the cylindrical body to after polishing. and preferably polished.

As a result, warping and deformation of the roller body 2 due to expansion and contraction during secondary cross-linking can be suppressed.
Further, by polishing while rotating around the shaft 4, the workability of the polishing can be improved, and the fluctuation of the outer peripheral surface 5 can be suppressed.
As described above, the shaft 4 is inserted through the through hole 3 of the cylindrical body before the secondary cross-linking through the conductive adhesive, particularly the conductive thermosetting adhesive, and then the secondary cross-linked. Alternatively, an object having an outer diameter larger than the inner diameter of the through hole 3 may be press-fitted into the through hole 3 .

In the former case, the cylindrical body is secondarily crosslinked by heating in an oven, and the thermosetting adhesive is cured at the same time, so that the shaft 4 is electrically and mechanically joined to the roller body 2. fixed to
In the latter case, electrical connection and mechanical fixation are completed at the same time as the shaft 4 is press-fitted.

Further, as described above, both methods may be used together to electrically connect the shaft 4 to the roller body 2 and mechanically fix them.
In the embodiment shown in FIG. 1, the roller body 2 has a single-layer structure made of a cross-linked foamed rubber composition for a transfer roller containing the components described above, but the roller body has a laminated structure of two or more layers. may be

In that case, the outermost layer constituting the outer peripheral surface may be formed by cross-linking and foaming the rubber composition for the transfer roller.
The transfer roller of the present invention can be used by being incorporated in various image forming apparatuses using electrophotography, such as laser printers, electrostatic copiers, plain paper facsimile machines, and multifunction machines thereof.

《Roller Resistance》
<Measurement of roller resistance value under normal temperature and humidity>
FIG. 2 is a diagram explaining a method of measuring the roller resistance value of the transfer roller.
1 and 2, in this measuring method, an aluminum drum 6 that can be rotated at a constant rotational speed is prepared, and a roller resistance value is measured from above on the outer peripheral surface 7 of the prepared aluminum drum 6. The outer peripheral surface 5 of the roller body 2 of the transfer roller 1 to be measured is brought into contact.

A DC power source 8 and a resistor 9 are connected in series between the shaft 4 of the transfer roller 1 and the aluminum drum 6 to form a measurement circuit 10 . The DC power supply 8 connects the shaft 4 on the (-) side and the resistor 9 on the (+) side.
Next, in a normal temperature and normal humidity environment with a temperature of 23° C. and a relative humidity of 55%, a load F of 500 g is applied to each end of the shaft 4 and the roller body 2 is pressed against the aluminum drum 6, and the aluminum drum 6 is rotated. Let

While continuing to rotate, an applied voltage E of 1000 V DC is applied from the DC power source 8 between the transfer roller 1 and the aluminum drum 6. After 30 seconds, the detected voltage V applied to the resistor 9 is measured.
The measurement is performed 32 times in the circumferential direction of the transfer roller 1 rotating with the rotation of the aluminum drum 6, and the average value is obtained.

At this time, the resistance value r of the resistor 9 is adjusted in the range of 100 Ω to 10 kΩ in accordance with the level of the roller resistance value so that the effective digits of the measured value of the roller resistance value are maximized.
Based on the average value of the measured detected voltage V and the applied voltage E (=1000 V), the roller resistance value R of the transfer roller 1 is basically expressed by the formula (i'):
R=r×E/V−r(i′)
sought by

However, since the −r term in formula (i′) can be regarded as minute, in the present invention formula (i):
R=r×E/V (i)
A roller resistance value R _NN (Ω) of the transfer roller 1 under a normal temperature and normal humidity environment is assumed to be the value obtained by the above.
The roller resistance value R _NN (Ω) may be within a range suitable for the transfer roller.
Specifically, it is preferably 6.6 or more, particularly preferably 6.8 or more, and 8.5 or less, particularly preferably 7.8 or less, in terms of common logarithm _logRNN .

<Evaluation of stability of roller resistance value due to differences in usage environment>
The roller resistance value R was measured under a low temperature and low humidity environment with a temperature of 10 ° C. and a relative humidity of 20%, and under a high temperature and high humidity environment with a temperature of 32 ° C. and a relative humidity of 80%. A resistance value R _LL (Ω) and a roller resistance value R _HH (Ω) under a high-temperature and high-humidity environment are obtained.
Then, the difference logR _LL -logR _HH (=ΔlogR) between the logarithmic value logR _LL and logR _HH of both roller resistance values is obtained, and if the difference is 2.2 or less, the variation is small (○), and 2.2 is Those exceeding are evaluated as large fluctuations (x).

<Evaluation of stability of roller resistance during continuous energization>
1 and 2, a load F of 500 g is applied to both ends of the shaft 4, and the roller body 2 is pressed against the aluminum drum 6. A DC power supply 8 of 2,000 V is applied between the roller body 2 and the aluminum drum 6. The applied voltage E is continuously applied.
During this continuous energization, the aluminum drum 6 stops rotating so that the same portion of the roller body 2 is always kept in contact with the aluminum drum 6 .
The resistance value r of the resistor 9 is also adjusted in the range of 100Ω to 10kΩ in accordance with the level of the roller resistance value so that the effective digits of the measured value of the roller resistance value are as large as possible.

Next, the transition of the detected voltage V applied to the resistor 9 immediately after the start of energization is recorded, and the roller resistance value R ₀ (Ω) at the start of energization and the roller resistance value R ₁ (Ω) at the time when one hour has passed since the start of energization Ω).
The measurement is carried out under normal temperature and humidity conditions of 23° C. and 55% relative humidity.
Then, the ratio R ₁ /R ₀ of the resistance values of both rollers is obtained as the increase ratio of the roller resistance values. It is evaluated as (×).

EXAMPLES The present invention will be further described below based on examples and comparative examples, but the configuration of the present invention is not necessarily limited to these examples.
<Example 1>
(Preparation of rubber composition for transfer roller)
As the rubber, the following four types were used.

GECO (I): Epichromer CG104 [EO/EP/AGE = 35.5/62.0/2.5 (molar ratio) manufactured by Osaka Soda Co., Ltd., Mooney Viscosity ML (1+4) 100°C: 60 ] 38 parts by mass GECO (II): HYDRIN T3106 [EO / EP / AGE = 56.0 / 39.3 / 4.7 (molar ratio) manufactured by Nippon Zeon Co., Ltd., Mooney viscosity ML (1 + 4) 100° C.: 60] 20 parts by mass NBR: N250SL manufactured by JSR Corporation [low nitrile NBR, non-oil-extended, acrylonitrile content: 19.5%, Mooney viscosity ML (1+4) 100° C.: 43] 29 parts by mass EPDM: Esprene (registered trademark) 505A manufactured by Sumitomo Chemical Co., Ltd. [diene component: ENB, non-oil-extended, ethylene content: 50%, diene content: 9.5%, Mooney viscosity ML (1+4) 100°C: 47] 13 mass Parts While masticating 100 parts by mass of the above rubber, the following components were blended and kneaded.

Each component in Table 1 is as follows, and parts by mass in the table are parts by mass per 100 parts by mass of the total amount of rubber.
Filler i: carbon black HAF [SEAST (registered trademark) 3 manufactured by Tokai Carbon Co., Ltd.]
Filler ii: heavy calcium carbonate [BF300 manufactured by Bihoku Funka Kogyo Co., Ltd.]
Crosslinking aid i: stearic acid [Tsubaki manufactured by NOF Corporation]
Crosslinking aid ii: 2 types of zinc oxide [manufactured by Mitsui Mining & Smelting Co., Ltd.]
Foaming agent: ADCA (trade name Vinihole AC#3 manufactured by Eiwa Kasei Kogyo Co., Ltd.)
Foaming aid: urea-based foaming aid [trade name Cellpaste 101 manufactured by Eiwa Kasei Kogyo Co., Ltd.]
Acid acceptor: hydrotalcites [DHT-4A (registered trademark)-2 manufactured by Kyowa Chemical Industry Co., Ltd.]
Antiaging agent i: 4,4′-bis(α,α-dimethylbenzyl)diphenylamine [Nocrac (registered trademark) CD manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.]
Antiaging agent ii: Zinc salt of 2-mercaptobenzimidazole [Nocrac MBZ manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd.]
Next, while continuing kneading, the following cross-linking components were blended and further kneaded to prepare a rubber composition for a transfer roller.

Each component in Table 2 is as follows, and parts by mass in the table are parts by mass per 100 parts by mass of the total amount of rubber.
Cross-linking agent: 5% oil-treated powdered sulfur [manufactured by Tsurumi Chemical Industry Co., Ltd.]
Accelerator TS: tetramethylthiuram monosulfide [Sunceller (registered trademark) TS manufactured by Sanshin Chemical Industry Co., Ltd., thiuram-based accelerator]
Accelerator DM: di-2-benzothiazolyl disulfide [Noxeller (registered trademark) DM manufactured by Ouchi Shinko Kagaku Kogyo Co., Ltd., thiazole-based accelerator]
The ratio PA of GECO (II) per 100 parts by weight of GECO (I) is 52.6 parts by weight, and the total ratio PB of GECO (I) and GECO (II) in the total amount of 100 parts by weight of rubber is 58 parts by weight. there were.

(Manufacture of transfer roller)
The prepared rubber composition for a transfer roller was supplied to a single-screw extruder and extruded into a cylindrical shape, then cut into a predetermined length and attached to a temporary shaft for cross-linking.
Then, in the vulcanizing can, the tubular body was pressurized and heated by pressurized steam, and the tubular body was foamed by the gas generated by the decomposition of the foaming agent, and the rubber was crosslinked.
The conditions for cross-linking are adjusted so that the 95% torque rise time t measured by a curastometer is about 95 minutes. It was set so that a sufficient amount of cross-linking was obtained.

Next, this cylindrical body is reattached to a shaft coated with a conductive thermosetting adhesive on the outer peripheral surface, heated in an oven for secondary cross-linking, and curing of the thermosetting adhesive. It was electrically connected to the shaft and mechanically fixed.
Then, after shaping both ends of the cylindrical body, the outer peripheral surface was finished by traverse grinding using a cylindrical grinder to form a roller body, thereby manufacturing a transfer roller.

<Example 2>
A rubber composition for a transfer roller was prepared in the same manner as in Example 1 except that the amount of GECO (II) was changed to 30 parts by mass and the amount of NBR was changed to 19 parts by mass, and a transfer roller was manufactured.
The ratio PA of GECO (II) per 100 parts by weight of GECO (I) is 78.9 parts by weight, and the total ratio PB of GECO (I) and GECO (II) in 100 parts by weight of the total amount of rubber is 68 parts by weight. there were.

<Example 3>
As GECO (I), Epichromer CG102 [EO/EP/AGE=56.0/40.0/4.0 (molar ratio), Mooney viscosity A rubber composition for a transfer roller was prepared in the same manner as in Example 1, except that the same amount of ML (1+4) 100° C.:55] was blended, and a transfer roller was manufactured.
The ratio PA of GECO (II) per 100 parts by weight of GECO (I) is 52.6 parts by weight, and the total ratio PB of GECO (I) and GECO (II) in the total amount of 100 parts by weight of rubber is 58 parts by weight. there were.

<Example 4>
A rubber composition for a transfer roller was prepared in the same manner as in Example 3 except that the amount of GECO (I) was 31.45 parts by mass, the amount of GECO (II) was 16.55 parts by mass, and the amount of NBR was 39 parts by mass. Materials were prepared and transfer rollers were manufactured.
The ratio PA of GECO (II) per 100 parts by weight of GECO (I) is 52.6 parts by weight, and the total ratio PB of GECO (I) and GECO (II) in the total amount of 100 parts by weight of rubber is 48 parts by weight. there were.

<Example 5>
A rubber composition for a transfer roller was prepared in the same manner as in Example 3 except that the amount of GECO (I) was 24.9 parts by mass, the amount of GECO (II) was 13.1 parts by mass, and the amount of NBR was 49 parts by mass. Materials were prepared and transfer rollers were manufactured.
The ratio PA of GECO (II) per 100 parts by weight of GECO (I) is 52.6 parts by weight, and the total ratio PB of GECO (I) and GECO (II) in the total amount of 100 parts by weight of rubber is 38 parts by weight. there were.

<Comparative Example 1>
A rubber composition for a transfer roller was prepared in the same manner as in Example 3 except that the amount of GECO (I) was 48 parts by mass, the amount of NBR was 39 parts by mass, and GECO (II) was not blended. manufactured rollers.
The ratio PA of GECO (II) per 100 parts by weight of GECO (I) was 0 parts by weight, and the total ratio PB of GECO (I) and GECO (II) in 100 parts by weight of the total amount of rubber was 48 parts by weight. .

<Comparative Example 2>
A rubber composition for a transfer roller was prepared in the same manner as in Example 3 except that the amount of GECO (I) was changed to 58 parts by mass and GECO (II) was not blended, and a transfer roller was manufactured.
The ratio PA of GECO (II) per 100 parts by weight of GECO (I) was 0 parts by weight, and the total ratio PB of GECO (I) and GECO (II) in 100 parts by weight of the total amount of rubber was 58 parts by weight. .

<Comparative Example 3>
Epichromer CG102 [EO / EP / AGE = 56.0 / 40.0 / 4.0 (molar ratio), Mooney viscosity ML (1 + 4) 100 ° C.: 55] 38 parts by mass, both of which are GECO (I), and epichromer CG104 [EO / EP / AGE = 35.5 / 62.0 / 2.5 (molar ratio), Mooney viscosity ML (1 + 4) 100 ° C.: 60] 20 parts by mass and blended with GECO (II) A rubber composition for a transfer roller was prepared in the same manner as in Example 3, except that the transfer roller was manufactured.
The ratio PA of GECO (II) per 100 parts by weight of GECO (I) was 0 parts by weight, and the total ratio PB of GECO (I) and GECO (II) in 100 parts by weight of the total amount of rubber was 58 parts by weight. .

<Comparative Example 4>
Epichromer CG102 [EO / EP / AGE = 56.0 / 40.0 / 4.0 (molar ratio), Mooney viscosity ML (1 + 4) 100 ° C.: 55] 28 parts by mass, both of which are GECO (I), and epichromer CG104 [EO / EP / AGE = 35.5 / 62.0 / 2.5 (molar ratio), Mooney viscosity ML (1 + 4) 100 ° C.: 60] 30 parts by mass and GECO (II) is blended A rubber composition for a transfer roller was prepared in the same manner as in Example 3, except that the transfer roller was manufactured.
The ratio PA of GECO (II) per 100 parts by weight of GECO (I) was 0 parts by weight, and the total ratio PB of GECO (I) and GECO (II) in 100 parts by weight of the total amount of rubber was 58 parts by weight. .

<Roller resistance value>
(Measurement of roller resistance value _RNN under normal temperature and humidity environment)
The roller resistance value R _NN (Ω) of the transfer rollers manufactured in Examples and Comparative Examples was measured under a normal temperature and normal humidity environment with a temperature of 23° C. and a relative humidity of 55% according to the measurement method described above.

<Changes in roller resistance due to differences in usage environment>
Fluctuations in the roller resistance value (environmental fluctuations) of the transfer rollers manufactured in Examples and Comparative Examples due to differences in usage environments were evaluated by the method described above.

<Increase in roller resistance during continuous energization>
The transfer rollers manufactured in Examples and Comparative Examples were evaluated for an increase in roller resistance value (increase in energization) during continuous energization by the method described above.
Tables 3 and 4 show the above results.

From the results of Examples 1 to 5 and Comparative Examples 1 to 4 in Tables 3 and 4, together with NBR, GECO (I) having an AGE content of 0.1 to 4.0 mol% and GECO (I) having an AGE content of 0.1 to 4.0 mol% and By using only two types of GECO (II), which is 4.5 to 6.0 mol%, the fluctuation of the roller resistance value due to the difference in the usage environment and the increase in the roller resistance value during continuous energization are small. It was found that the value is stable and a transfer roller capable of continuously forming images of good quality can be obtained.

Further, from the results of Examples 1 to 5, the ratio PA of GECO (II) per 100 parts by mass of GECO (I) is preferably 30 to 95 parts by mass. It has been found that the total proportion PB of I) and GECO (II) is preferably between 30 and 75 parts by weight.
Further, from the results of Examples 1 to 5, it is preferable to use GECO(I) having an EO content of 30 to 60 mol%. It has been found that it is preferable to use one having a viscosity ML(1+4) of 50 or more at 100°C.

From the results of Examples 1 to 5, it was found that the rubber preferably further contains ethylene-α-olefin-nonconjugated polyene copolymer rubber such as EPDM.

F Load V Detection voltage 1 Transfer 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 Measuring circuit

Claims (8)

Rubber containing acrylonitrile-butadiene rubber and epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer, and epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer comprising a crosslinking component for crosslinking said rubber teeth,
(I) an epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer having an allyl glycidyl ether content of 0.1 mol% or more and 4.0 mol% or less; and
(II) an epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer having an allyl glycidyl ether content of 4.5 mol% or more and 6.0 mol% or less;
Rubber compositions for transfer rollers, which are two types of Per 100 parts by mass of the epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer of (I), the ratio of the epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer of (II) is 30 parts by mass or more. , 95 parts by mass or less. Total of the epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (I) and the epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (II) in the total amount of 100 parts by mass of the rubber is 30 parts by mass or more and 75 parts by mass or less, the rubber composition for a transfer roller according to claim 1 or 2. 4. The transfer roller according to claim 1, wherein the ethylene oxide content of the epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (I) is 30 mol % or more and 60 mol % or less. rubber composition for Both the epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (I) and the epichlorohydrin-ethylene oxide-allyl glycidyl ether terpolymer (II) have a Mooney viscosity of ML(1+4) of 100° C. 5. The rubber composition for a transfer roller according to any one of claims 1 to 4, wherein the R.sub.i is 50 or more. 6. The rubber composition for a transfer roller according to claim 1, further comprising an ethylene-α-olefin-nonconjugated polyene copolymer rubber. 7. The rubber composition for a transfer roller according to claim 1, further comprising a foaming component for foaming the rubber. A transfer roller comprising a porous roller body made of a crosslinked product of the rubber composition for a transfer roller according to any one of claims 1 to 7.

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