JP7153187B2 - Developing roller and manufacturing method thereof - Google Patents

Description

The present invention relates to a developing roller and its manufacturing method.

For example, in an image forming apparatus using electrophotography, such as a laser printer, an electrostatic copier, a plain paper facsimile machine, or a combination of these machines, an electrostatic latent image formed on the surface of a photoreceptor is formed by toner. A developer roller is used to develop the image.
The developing roller includes, for example, a roller body formed by molding a conductive rubber composition into a cylindrical shape and cross-linked, and a shaft made of metal or the like, which is inserted and fixed through a through hole in the center of the roller body. and the like are used.

In the development using the developing roller, the developing roller is provided in the developing section containing the toner of the image forming apparatus, and the tip of the amount regulating blade (charging blade) is brought into contact with the outer peripheral surface of the roller body of the developing roller. The developing roller is rotated in this state.
As a result, the toner in the developing section is charged and adheres to the outer peripheral surface of the roller body. is regulated, and a toner layer having a substantially constant thickness is formed on the outer peripheral surface.

At the same time, an electrostatic latent image is formed on the surface of the photoreceptor by uniformly charging it and then exposing it to light.
Next, when the developing roller is further rotated in this state to convey the toner layer to the vicinity of the surface of the photoreceptor, the toner forming the toner layer is transferred according to the electrostatic latent image formed on the surface of the photoreceptor. It selectively moves to the surface of the photoreceptor to develop the electrostatic latent image into a toner image.

The axial end of the roller body of the developing roller is generally sealed with a sealing member in order to prevent the toner adhered to the outer peripheral surface of the roller body from leaking out of the developing section. .
The seal member is made of, for example, felt, and is fixed to the housing of the developing section or the like, and is brought into sliding contact with the outer peripheral surface of the rotating developing roller at the end portion in the axial direction of the roller main body.

However, for example, in a high-endurance image forming apparatus (high-endurance machine) that is set to perform maintenance every image formation of about 8,000 sheets, the seal member seals the image between the start of use and the first maintenance. Toner may leak from the end where it should be.
Toner leakage is caused by repeated image formation, which wears the outer peripheral surface of the axial end of the roller main body with which the seal member is slidably contacted, creating a gap between it and the seal member.

Further, for example, in an image forming apparatus (high-speed machine) with a high image forming speed, when image forming is repeated, the developing roller may generate heat due to friction between the seal member and the end portion of the roller body.
Therefore, in Patent Document 1, the axial end portion of the roller body with which the seal member is slidably contacted is formed of rubber having a low coefficient of friction, mainly silicone rubber, to suppress wear of the outer peripheral surface of the end portion. is being considered.

Further, in Patent Document 1, in order to further suppress wear, the entire outer peripheral surface of the roller body, including the ends, is coated with a surface treatment layer made of a cured product of an isocyanate compound, or a coating layer made of urethane or the like. are also being considered.
Among these, the surface treatment layer is formed by applying a treatment liquid containing an isocyanate compound to the entire outer peripheral surface of the roller body by a coating method such as a dip coating method, a roll coating method, or a spray coating method, followed by heating to cure the isocyanate compound. It is formed by reacting.

The coating layer is formed by applying a liquid coating agent containing urethane, acrylic urethane, nylon, NBR, etc. to the entire outer peripheral surface of the roller body by the same coating method, followed by drying and solidifying or heating and curing. be done.
However, forming the ends of the roller body from another rubber increases the manufacturing process and the materials used for the roller body, resulting in a decrease in the productivity of the developing roller and a high manufacturing cost. There is

In addition, when the entire outer peripheral surface of the roller body is covered with a surface treatment layer or a coating layer, the entire roller body becomes hard, and when the tip of the weight control blade is brought into contact with the nip, it becomes difficult to deform the nip. In some cases, a toner layer having a uniform thickness cannot be formed on the outer peripheral surface.
In addition, as described above, the surface treatment layer is formed using a treatment liquid, and the coating layer is formed using a liquid coating agent. There is also the issue of ease.

Moreover, the formed surface treatment layer and coat layer cannot follow the nip deformation of the roller body, and are likely to peel off and be lost from the outer peripheral surface of the roller body in a relatively short period of time.
And if the surface treatment layer and coating layer are lost in a short period of time, as mentioned above, toner leakage due to abrasion during use in high-endurance machines and heat generation in high-speed machines will be sufficiently prevented. There are cases where it cannot be controlled.

In Patent Document 2, in order to suppress wear of the outer peripheral surface of the ends of the roller body, it is considered to selectively coat the ends with a wear-resistant material layer.
The wear-resistant material layer is formed by, for example, applying a liquid coating containing urethane resin, phenolic resin, fluororesin, silicone resin, etc. by the coating method described above, followed by drying and solidifying or heating and curing. .

Further, in Patent Document 2, it is also considered to form a resin layer by applying the paint to the entire surface of the roller body, and to apply a thick resin layer only to the ends of the roller body to form the wear-resistant material layer. there is
Furthermore, in Patent Document 3, in order to suppress the heat generation of the developing roller, it is studied to increase the thermal conductivity by forming the roller body from silicone rubber containing metal silicon particles.

Further, in Patent Document 3, in order to further suppress heat generation by reducing friction, it is also considered to coat the outer peripheral surface of the end portion in the axial direction of the roller body with an end protective layer containing a fluorine-containing resin. .
Further, in Patent Document 3, covering the entire surface of the roller body with a coating layer containing urethane resin is also considered.

However, the wear-resistant material layer and resin layer described in Patent Document 2, and the edge protection layer and coat layer described in Patent Document 3 also have the same problems as the surface treatment layer and coat layer described in Patent Document 1. have.
That is, since the wear-resistant material layer and the resin layer described in Patent Document 2 are formed using a liquid paint as described above, various problems are likely to occur during the respective formation processes.

Moreover, the formed wear-resistant material layer and resin layer cannot follow the deformation of the nip of the roller body and are likely to peel off and be lost from the outer peripheral surface of the roller body in a relatively short period of time.
In particular, if the wear-resistant material layer is lost in a short period of time, toner leakage due to abrasion during use in high-endurance machines and heat generation in high-speed machines cannot be sufficiently suppressed. occur.

In addition, when the entire outer peripheral surface of the roller body is covered with a resin layer, the entire roller body becomes hard, and when the tip of the amount regulating blade is brought into contact, the nip is less likely to be deformed, and the outer periphery of the roller body is hardened. In some cases, a toner layer having a uniform thickness cannot be formed on the surface.
In addition, since the edge protection layer described in Patent Document 3 is formed using a liquid resin composition containing a fluorine-containing resin, and the coating layer is formed using a liquid resin composition containing a urethane resin, the respective layers Various problems tend to occur during the formation process.

Moreover, the formed end protection layer and coat layer cannot follow the deformation of the nip of the roller body and are likely to peel off and be lost from the outer peripheral surface of the roller body in a relatively short period of time.
In addition, especially if the end protective layer is lost in a short period of time, toner leakage due to abrasion during use in a high-endurance machine and heat generation in a high-speed machine cannot be sufficiently suppressed. .

In addition, when the entire outer peripheral surface of the roller body is covered with a coating layer, the entire roller body becomes hard, and when the tip of the amount regulating blade is brought into contact, the nip is less likely to be deformed, and the outer periphery of the roller body is hardened. In some cases, a toner layer having a uniform thickness cannot be formed on the surface.
In the following, the outer peripheral surface of the roller body is covered with the surface treatment layer and coat layer of Patent Document 1, the wear-resistant material layer and resin layer of Patent Document 2, and the edge protection layer and coat layer of Patent Document 3. Conventional layers made of resin, rubber, or the like are sometimes collectively referred to as a "coating layer."

Japanese Patent Application Laid-Open No. 2001-222163 JP-A-10-293453 JP 2018-59993 A

An object of the present invention is to integrally form the entire roller body from a crosslinked product of the same rubber composition without forming the ends of the roller body with another rubber or forming a coating layer on the outer peripheral surface. To provide a developing roller in which friction is reduced while maintaining a simple structure and less likely to cause leakage of toner and heat generation, and to provide a method for manufacturing the developing roller.

The present invention includes a cylindrical roller body made of a crosslinked product of a rubber composition, and at both ends of the roller body in the axial direction, radially inward of the outer peripheral surface of the roller body and A cross-linked product of the rubber composition and a cured product of an isocyanate group-containing silane compound in the vicinity of the outer peripheral surface, including a cured region exposed on the outer peripheral surface, and an intermediate portion between the both ends of the roller body Part is a developing roller composed only of a crosslinked rubber composition that does not contain a cured product of the isocyanate group-containing silane compound .
The present invention also provides a method for manufacturing the developing roller of the present invention, comprising: forming the rubber composition into a tubular shape and cross-linking to form the roller main body ; A step of supplying a treatment liquid containing at least the isocyanate group-containing silane compound to the outer peripheral surface of the portion, and selectively impregnating the treatment liquid radially inward of the both end portions from the outer peripheral surface; and a curing reaction of the isocyanate group-containing silane compound in the impregnated treatment liquid, so that the middle portion between the both ends of the roller body is a rubber that does not contain a cured product of the isocyanate group-containing silane compound. While formed only by the crosslinked product of the composition, the crosslinked product of the rubber composition and the isocyanate group-containing silane are placed radially inward of the outer peripheral surface of the both ends and in the vicinity of the outer peripheral surface. The method for manufacturing the developing roller includes a step of forming the cured region exposed on the outer peripheral surface, the developing roller containing a cured product of a compound.

According to the present invention, the entire roller body is integrally formed of the same crosslinked rubber composition without forming the end portions of the roller body with another rubber or forming a coating layer on the outer peripheral surface. Therefore, it is possible to provide a developing roller which has a simple structure and is less likely to cause toner leakage or heat generation, and a method of manufacturing the same.

FIG. (a) is a perspective view showing the appearance of an example of an embodiment of the developing roller of the present invention, and FIG. A cross-sectional view schematically showing the internal structure of both ends, FIG. It may be abbreviated.) is a cross-sectional view schematically showing the internal structure.

<<Developing Roller and its Manufacturing Method>>
<Developing roller>
FIG. 1(a) is a perspective view showing the appearance of an example of an embodiment of the developing roller of the present invention, and FIG. A cross-sectional view schematically showing the internal structure of both ends in the axial direction, and FIG. It is a sectional view showing.

Referring to each figure, the developing roller 1 of this example includes a non-porous single-layer cylindrical roller body 2 integrally formed of a crosslinked product of the same rubber composition. A shaft 4 is inserted through a through hole 3 in the center of the roller body 2 and fixed.
The shaft 4 is integrally made 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 pressing it into the hole 3, it is electrically connected to the roller body 2 and mechanically fixed.
Alternatively, both of these methods may be used together to electrically connect the shaft 4 to the roller body 2 and mechanically fix it.

The entire outer peripheral surface 5 of the roller body 2 is exposed without being covered with a coating layer made of resin, rubber, or the like.
That is, the roller main body 2 does not include (exclude) the coating layer coated on the outer peripheral surface 5 .
The roller body 2 has an isocyanate group-containing silane compound in a cross-linked rubber composition integrally forming the roller body 2 at both ends 2a in the axial direction with which seal members (not shown) are slidably contacted. A substantially cylindrical cured region 21 containing a cured product of .

The hardened region 21 is located radially inward of the outer peripheral surface 5 of the end portion 2a of the roller body 2 and in the vicinity of the outer peripheral surface 5 (hereinafter sometimes abbreviated as “surface layer portion”). thinly formed.
Further, the hardened region 21 is exposed on the outer peripheral surface 5 without being covered with the coating layer as described above.

The cured region 21 is formed by, for example, selectively impregnating the end portion 2a of the roller body 2 from the outer peripheral surface 5 with a treatment liquid containing at least an isocyanate group-containing silane compound, as will be described later, and then applying the isocyanate group-containing silane compound. It is formed by, for example, curing a compound.
The isocyanate group-containing silane compound can undergo a curing reaction, for example, by reacting with moisture in the air.

The cured region 21 formed by the curing reaction is in a state in which the cured product of the isocyanate group-containing silane compound is mixed in the crosslinked product of the rubber composition forming the roller body 2 .
Therefore, the hardness of the outer peripheral surface 5 of the end portion 2 a of the roller body 2 can be increased by the cured product of the isocyanate group-containing silane compound contained in the cured region 21 .
Moreover, since the isocyanate group-containing silane compound contains silicon in the molecule, the cured product thereof is, for example, compared to the cured product of the aromatic diisocyanate compound widely used as the isocyanate compound described in Patent Document 1. It is also excellent in the effect of reducing friction.

Therefore, in combination with these factors, the friction on the outer peripheral surface 5 of the end portion 2a of the roller body 2 can be satisfactorily reduced by selecting and using the isocyanate group-containing silane compound.
Further, the cured region 21 is formed integrally with the entire roller body 2 by the crosslinked product of the rubber composition, as described above.

Therefore, even if the roller body 2 deforms in the nip, the hardened region 21 does not peel off from the roller body 2 in a short period of time and be lost unlike the conventional coating layer, which cannot follow the nip deformation.
Therefore, by providing the hardened region 21, the end portion 2a with which the seal member (not shown) is in sliding contact may be worn when used in a high-endurance machine, causing leakage of toner, or when used in a high-speed machine. heat generation can be suppressed for a longer period of time.

A non-impregnated region 22 to which the isocyanate group-containing silane compound in the treatment liquid impregnated from the outer peripheral surface 5 has not reached is present in the end portion 2 a of the roller body 2 radially inward of the cured region 21 .
That is, the non-impregnated region 22, together with the intermediate portion 2b of the roller body 2, consists only of a crosslinked rubber composition that does not contain a cured product of an isocyanate group-containing silane compound.

Moreover, the non-impregnated region 22 occupies most of the end portion 2a with respect to the very thin hardened region 21 .
Therefore, the roller body 2 does not include the above-described coating layer, and not only the intermediate portion 2b but also the end portions 2a having the hardened regions 21 have good properties as rubber, that is, flexibility and compression. The permanent strain is small and it is possible to maintain the characteristics that do not easily cause settling.

Therefore, when the tip of the amount regulating blade is brought into contact with the outer peripheral surface 5 of the roller body 2, the entire roller body 2 is uniformly nip-deformed, and a toner layer having a uniform thickness is formed on the outer peripheral surface 5. can be formed.
Furthermore, the roller main body 2 can maintain a simple structure in which the end portion 2a is not made of another rubber and the outer peripheral surface 5 is not coated with a coating layer.

Therefore, while maintaining such a simple structure and maintaining good rubber properties of the roller body 2, friction is reduced, and the effect of preventing toner leakage and heat generation is maintained for a long period of time. It becomes possible to
Although the thickness of the cured region 21 is not limited to this, it is preferably 500 μm or less, for example.

When the thickness of the hardened region 21 is larger than this range, the end portion 2a becomes too hard, the flexibility of the end portion 2a decreases, and the flexibility of the adjacent intermediate portion 2b tends to become uneven.
In addition, when the tip of the amount-regulating blade is brought into contact with the outer peripheral surface 5 of the roller body 2, the nip deformation of the entire roller body 2 becomes uneven, and the outer peripheral surface 5 has a uniform thickness. In some cases, the toner layer cannot be formed.

On the other hand, by setting the thickness of the hardened region 21 within the above range, it is possible to impart uniform flexibility to the end portion 2 a and thus to the entire roller body 2 .
Therefore, when the tip of the amount regulating blade is brought into contact with the outer peripheral surface 5 of the roller body 2 , the entire roller body 2 is uniformly nip-deformed, and a toner layer having a uniform thickness is formed on the outer peripheral surface 5 . can be formed.

As shown in FIG. 1(c), an oxide film 6 made of an oxide of a crosslinked product of the rubber composition may be formed on the outer peripheral surface 5 of the intermediate portion 2b.
The oxide film 6 is formed, for example, by irradiating the outer peripheral surface 5 of the intermediate portion 2b of the roller body 2 with ultraviolet light having a predetermined wavelength for a predetermined time period to oxidize the cured rubber composition exposed on the outer peripheral surface 5. be done.

When the oxide film 6 is formed, the oxide film 6 functions as a dielectric layer and the dielectric loss tangent of the developing roller 1 can be reduced.
In addition, since the oxide film 6 functions as a low-friction layer, it suppresses the toner from remaining or accumulating on the outer peripheral surface 5 of the roller body 2, thereby suppressing the influence of the toner on the formed image. Alternatively, the friction on the entire outer peripheral surface 5 can be reduced.

Furthermore, the oxide film 6 is a very thin film compared to the coating layer, and does not harden the entire roller body 2 like the coating layer.
Therefore, when the tip of the amount regulating blade is brought into contact with the outer peripheral surface 5 of the roller body 2, the roller body 2 is easily nip-deformed to form a toner layer having a uniform thickness on the outer peripheral surface 5. be able to.

Moreover, the oxide film 6 functions as a low-friction layer to reduce the friction of the outer peripheral surface 5 from the boundary between the end portion 2a and the intermediate portion 2b to the intermediate portion 2b.
Therefore, it is possible to further suppress the heat generation of the developing roller 1 by reducing the torque of the developing roller 1 as a whole, and to further suppress the leakage of toner by suppressing the wear at the boundary portion.

The oxide film 6 may be selectively formed only on the outer peripheral surface 5 of the intermediate portion 2b of the roller body 2, or may be formed on the entire outer peripheral surface 5 including the end portions 2a.
However, oxide film 6 may not be formed.
The "single layer structure" of the roller body 2 means that the number of layers made of rubber or the like is a single layer, and the oxide film 6 formed by irradiation of ultraviolet rays or the like is not included in the number of layers. .

<Isocyanate Group-Containing Silane Compound>
As described above, since the isocyanate group-containing silane compound contains silicon in the molecule, the cured product thereof has an excellent effect of reducing friction on the outer peripheral surface 5, compared to, for example, a cured product of an aromatic diisocyanate compound. there is
Therefore, by selecting and using an isocyanate group-containing silane compound, the thickness of the cured region 21 can be reduced, which provides the same friction reduction effect as compared with an aromatic diisocyanate compound or the like.

Further, the flexibility of the end portion 2a of the roller body 2 can be further increased, and the time required for impregnation with the treatment liquid can be shortened.
In addition, the isocyanate group-containing silane compound has excellent reactivity with water compared to aromatic diisocyanate compounds and the like, so as described above, for example, the time required for the curing reaction due to moisture in the air can be shortened. can also

Therefore, productivity of the developing roller 1 can be improved.
These facts are also apparent from the results of Examples and Comparative Examples, which will be described later.
Various silane compounds containing an isocyanate group in the molecule can be used as the isocyanate group-containing silane compound.
In particular, the isocyanate group-containing silane compound has the formula (1):
R ¹ —Si(NCO) ₃ (1)
[In the formula, R ¹ represents an isocyanate group or an alkyl group having 1 to 3 carbon atoms. ]
A compound represented by is preferred.

Further, specific examples of the isocyanate group-containing silane compound represented by formula (1) include, for example, tetraisocyanate silane in which R ¹ in formula ( ¹ ) is an isocyanate group, methyl At least one such as triisocyanate silane can be used.
These two compounds are excellent in the above-mentioned effects, and tetraisocyanate silane is particularly preferred.

<Manufacturing method of developing roller>
To manufacture the developing roller 1, first, the rubber composition is extruded into a cylindrical shape using, for example, an extruder, then cut into a predetermined length, and pressurized with pressurized steam in a vulcanization can. , heat to crosslink.
Next, the crosslinked cylindrical body is heated using an oven or the like to cause secondary crosslinking, cooled, and then ground to a predetermined outer diameter to form the roller body 2 .

The shaft 4 can be inserted through the through hole 3 and fixed at any time from after cutting the cylindrical body to after polishing. Cross-linking and polishing are preferred.
As a result, it is possible to suppress warping and deformation of the cylindrical body due to expansion and contraction during secondary cross-linking. It can suppress fringing.

As described above, the shaft 4 is inserted through the through hole 3 of the cylindrical body before secondary cross-linking via a conductive adhesive, particularly a conductive thermosetting adhesive, and then 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 subjected to secondary cross-linking by heating in an oven, and the thermosetting adhesive is cured at the same time, so that the shaft 4 is electrically joined to the roller body 2 and mechanically joined. fixed to

In the latter case, electrical connection and mechanical fixation are completed at the same time as press-fitting.
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.
Next, in the example of FIG. 1(a), both ends 2a of the roller body 2 in the axial direction are impregnated from the outer peripheral surface 5 with a treatment liquid containing at least an isocyanate group-containing silane compound.

In order to impregnate both ends 2a in the axial direction of the roller body 2 with the treatment liquid, for example, both ends 2a may be individually immersed in the treatment liquid.
Alternatively, the intermediate portion 2b of the roller body 2 is covered with a mask, and the end portion 2a is exposed, and the processing liquid is continuously supplied to the end portion 2a by an arbitrary coating method such as a spray method. good too.

The impregnation conditions are not particularly limited, but the impregnation temperature (environmental temperature and treatment liquid temperature) is preferably room temperature, that is, 15° C. or higher and 35° C. or lower, and particularly preferably 20° C. or higher.
This makes it possible to impregnate the end portion 2a with the treatment liquid as quickly as possible while suppressing rapid progression of the curing reaction of the isocyanate group-containing silane compound.

Also, depending on the combination of the isocyanate group-containing silane compound and the rubber composition forming the roller body 2, the concentration of the treatment liquid, etc., when the temperature is room temperature, the impregnation time is 1 minute or longer. is preferred, and the time is preferably 1 hour or less.
If the impregnation time is less than this range, it is not possible to impregnate the end portion 2a with an appropriate amount of the treatment liquid to form a continuous hardened region 21 that has an appropriate thickness and can satisfactorily reduce the friction of the outer peripheral surface 5. There is

On the other hand, if the impregnation time exceeds the above range, the thickness of the cured region 21 becomes too large, and the end 2a, and thus the roller body 2 as a whole, cannot maintain good rubber properties. Sometimes.
On the other hand, by setting the impregnation time within the above range, the end portions 2a are impregnated with an appropriate amount of the treatment liquid while maintaining good properties as a rubber in the entire roller body 2. It is possible to form a continuous hardened region 21 that has a thickness and can reduce the friction of the outer peripheral surface 5 satisfactorily.

In particular, when a solution of an organic solvent is used as the treatment liquid, even if the impregnation time is within the above range or shortened, the end portion 2a of the roller body 2 is quickly impregnated, and a better cured region is obtained. 21 can be formed, and the productivity of the developing roller 1 can be improved.
In order to adjust the impregnation time, for example, in the case of the immersion method, the time for continuously immersing each end 2a of the roller body 2 in the treatment liquid may be set within the above range.

Further, for example, in the case of a spray method or the like, the time for which the treatment liquid is continuously supplied to the end portion 2a may be set within the above range.
Next, when a predetermined impregnation time has elapsed, the end portion 2a is pulled up from the treatment liquid in the case of the immersion method, and after stopping the supply of the treatment liquid in the case of the spray method or the like, the outer peripheral surface 5 of the end portion 2a is Remove the processing liquid adhering to the

If the treatment liquid adhering to the outer peripheral surface 5 is not removed, the isocyanate group-containing silane compound remains on the outer peripheral surface 5 in a continuous or discontinuous state, and the isocyanate group-containing silane compound undergoes a curing reaction. A cured product is formed.
Then, the outer peripheral surface 5 of the end portion 2a becomes hard locally, or a hard projection made of a hardened material is formed on the outer peripheral surface 5.

As a result, the toner that passes between the developing roller 1 and the toner amount regulating blade and is triboelectrically charged is brought into pressure contact with the locally hardened portion of the outer peripheral surface 5 and fused to the toner amount regulating blade. In some cases, the formed image tends to have vertical streak-like density unevenness.
In contrast, as described above, by removing the processing liquid adhering to the outer peripheral surface 5, the occurrence of these problems can be suppressed.

In order to remove the processing liquid adhering to the outer peripheral surface 5 of the end portion 2a, the outer peripheral surface 5 pulled up from the processing liquid may be wiped off using, for example, a wiper made of non-woven fabric.
The roller body 2 from which the treatment liquid adhering to the outer peripheral surface 5 of the end portion 2a has been removed is allowed to stand still under a predetermined temperature and humidity environment, and the isocyanate group-containing silane compound impregnated in the end portion 2a is treated as described above. As described above, the curing reaction is caused by the moisture in the air.

Then, as shown in FIGS. 1(a) and 1(b), the surface layer in the end portion 2a of the roller body 2 contains the crosslinked product of the rubber composition and the cured product of the isocyanate group-containing silane compound, and the outer peripheral surface 5 An exposed substantially cylindrical hardened region 21 can be formed.
For example, an isocyanate group-containing silane compound that is solid at room temperature may be used as a treatment liquid in the form of a solution diluted with any organic solvent.

On the other hand, the isocyanate group-containing silane compound, which is liquid at room temperature, may be used as the treatment liquid as it is, or may be diluted with any organic solvent and used as the treatment liquid.
However, although it depends on the type of rubber forming the roller body, in order to reduce the contact angle of the treatment liquid with respect to the outer peripheral surface 5 of the roller body and quickly impregnate the treatment liquid, a liquid isocyanate group-containing silane is required. Even if it is a compound, it is preferable to use it as a treatment liquid in the form of a solution diluted with an arbitrary organic solvent.

Various organic solvents capable of dissolving the isocyanate group-containing silane compound can be used as the organic solvent.
Examples of organic solvents include one or more of n-pentane, n-octane, toluene, methylene chloride, n-hexanol, and the like.
The oxide film 6 may be formed either before or after forming the cured region 21 .

As described above, the oxide film 6 is preferably formed by irradiating at least the outer peripheral surface 5 of the intermediate portion 2b of the roller body 2 with ultraviolet rays.
That is, only the outer peripheral surface 5 of the intermediate portion 2b of the roller body 2 or the entire outer peripheral surface 5 including the end portions 2a is irradiated with ultraviolet light having a predetermined wavelength for a predetermined time, and the vicinity of the outer peripheral surface 5 is irradiated. The oxide film 6 can be formed by oxidizing the constituent rubber composition.

Therefore, the process of forming the oxide film 6 is simple and efficient, and it is possible to prevent a decrease in productivity of the developing roller 1 and an increase in manufacturing cost.
Moreover, the oxide film 6 formed by irradiation with ultraviolet rays does not cause the above-described problems of the conventional coating layer, and is excellent in thickness uniformity, adhesion to the roller body 2, and the like.

The wavelength of the ultraviolet rays to be irradiated is preferably 100 nm or more, 400 nm or less, particularly 300 nm or less, in consideration of efficiently oxidizing the rubber composition and forming the oxide film 6 having excellent functions as described above. is preferred.
The irradiation time is preferably 30 seconds or longer, particularly 1 minute or longer, and preferably 30 minutes or shorter, particularly 20 minutes or shorter.

However, the oxide film 6 may be formed by another method, or may not be formed.
<<Rubber composition>>
The rubber composition forming the roller body 2 of the developing roller 1 is prepared by blending rubber with a cross-linking component for cross-linking the rubber and various additives.
In order to impart electrical conductivity to the rubber composition and adjust the roller resistance value of the developing roller 1 within a suitable range, an ion-conductive rubber composition will be described below. A rubber composition having either a high conductivity or an electronic conductivity may be used.

<Rubber>
As described above, in order to impart ionic conductivity to the rubber composition, it is preferable to use an ionic conductive rubber as the rubber.
As the rubber, it is preferable to use a diene rubber together with the ion conductive rubber.

By using these rubbers together, it is possible to impart good workability to the rubber composition and improve the mechanical strength, durability, etc. of the roller body.
Also, the roller body can be imparted with good properties as rubber.
(ion conductive rubber)
Examples of ion conductive rubber include epichlorohydrin rubber, polyether rubber, and the like.

Among these, epichlorohydrin rubber includes, 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 terpolymer and the like.

Examples of polyether rubbers include ethylene oxide-allyl glycidyl ether binary copolymers and ethylene oxide-propylene oxide-allyl glycidyl ether terpolymers.
Among them, copolymers containing ethylene oxide, particularly ECO and/or GECO are preferred.

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

On the other hand, if the ethylene oxide content exceeds the above range, crystallization of ethylene oxide occurs, hindering the segmental motion of the molecular chains, so that the roller resistance of the developing roller tends to increase.
In addition, the roller body after cross-linking may become too hard, and the viscosity of the rubber composition before cross-linking may increase when heated and melted, resulting in a decrease in processability of the rubber composition.

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

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 developing roller.
However, if the allyl glycidyl ether content is less than this range, such function cannot be sufficiently obtained, and thus the roller resistance value of the developing roller may not be sufficiently lowered.

On the other hand, allyl glycidyl ether functions as a cross-linking point during cross-linking of GECO.
Therefore, if the allyl glycidyl ether content exceeds the above range, the crosslink density of GECO becomes too high, hindering the segmental movement of the molecular chains, and on the contrary, the roller resistance of the developing roller tends to increase. .
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 19.5 mol % or more, and preferably 69.5 mol % or less, particularly 60 mol % or less.
As GECO, in addition to the copolymer in the narrow sense obtained by copolymerizing the three kinds of monomers described above, modified epichlorohydrin-ethylene oxide copolymer (ECO) modified with allyl glycidyl ether things are also known.

Either of these GECOs can be used in the present invention.
One or more of these ion-conductive rubbers can be used.
(Diene rubber)
Examples of 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, it is preferable to use both BR and CR as diene rubbers.
However, both rubbers may be used in combination of two or more.
・ BR
BR functions to impart good properties as rubber, particularly to the roller body.
BR also functions to improve the chargeability of positively charged toner, and to improve the fluidity and moldability of the rubber composition before cross-linking.

Furthermore, BR functions as a material that is oxidized by ultraviolet irradiation in an oxidizing atmosphere to form an oxide film on the outer peripheral surface of the roller body.
Any of various crosslinkable BRs having a polybutadiene structure in the molecule can be used as the BR.
Particularly preferred is a high cis BR having a cis-1,4 bond content of 95% or more, which can exhibit good properties as a rubber over a wide temperature range from high to low.

As BR, there are an oil-extended type in which extender oil is added to adjust flexibility and a non-oil-extended type in which extender oil is not added. It is preferred to use a non-oil-extended type of BR, which does not contain extender oil which can be a material.
One or more of these BRs can be used.
・CR
CR functions particularly to improve the flexibility of the roller body and enhance the image durability of the developing roller.

The image durability is an index representing how long the image quality of formed images can be maintained while suppressing the deterioration of the toner when the same toner is repeatedly used for image formation.
That is, only a small portion of the toner contained in the developing section of the image forming apparatus is used for one image formation, and most of the remaining toner repeatedly circulates within the developing section.
Therefore, the extent to which the roller body of the developing roller, which is provided in the developing section and repeatedly contacts the toner, damages the toner, or not, is a key factor in improving image durability.

When the flexibility of the roller main body is reduced and the image durability is reduced, the image quality of the formed image tends to gradually deteriorate as the image formation is repeated.
Therefore, the conductive roller is required to have a roller body with excellent flexibility in order to improve image durability.
CR also functions to improve the charging characteristics of positively charged toner in particular, and to finely adjust the roller resistance value of the developing roller since CR itself is a polar rubber.

Furthermore, CR also functions as a material that is oxidized by ultraviolet irradiation in an oxidizing atmosphere and forms an oxide film on the outer peripheral surface of the roller body.
CR is synthesized, for example, by emulsion polymerization of chloroprene, and is classified into a sulfur-modified type and a non-sulfur-modified type according to the type of molecular weight modifier used at that time.
Of these, sulfur-modified CR is synthesized by plasticizing a polymer obtained by copolymerizing chloroprene and sulfur as a molecular weight modifier with thiuram disulfide or the like to adjust the viscosity to a predetermined value.

On the other hand, non-sulfur-modified CR is classified into, for example, mercaptan-modified type, xanthogen-modified type, and the like.
Of these, mercaptan-modified CR is synthesized in the same manner as sulfur-modified CR, except that alkylmercaptans such as n-dodecylmercaptan, tert-dodecylmercaptan and octylmercaptan are used as molecular weight modifiers.

The xanthogen-modified CR is also synthesized in the same manner as the sulfur-modified CR, except that an alkylxanthogen compound is used as a molecular weight modifier.
Furthermore, CR is classified into a type with a slow crystallization rate, a type with a moderate rate of crystallization, and a type with a high rate of crystallization based on its crystallization rate.
In the present invention, any type of CR may be used, but a non-sulphur-modified CR with a slow crystallization rate is preferred.

As CR, a copolymer rubber of chloroprene and other copolymer components may be used.
Such other copolymer components include, for example, 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, styrene, acrylonitrile, methacrylonitrile, isoprene, butadiene, acrylic acid, acrylic acid One or more of esters, methacrylic acid, methacrylic acid esters, and the like may be used.

Further, CR includes an oil-extended type in which extender oil is added to adjust flexibility and a non-oil-extended type in which extender oil is not added. It is preferred to use a non-oil-extended CR that does not contain extender oil that can be a bleeding material.
One or more of these CRs can be used.
(Proportion of rubber)
The ratio of the ion conductive rubber is preferably 10 parts by mass or more and preferably 40 parts by mass or less in 100 parts by mass of the total rubber.

The ratio of the diene rubber is the remaining amount of the ion conductive rubber.
That is, the proportion of the diene rubber may be set so that the total amount of the rubber is 100 parts by mass when the proportion of the ion conductive rubber is set to a predetermined value within the above range.
If the ratio of the ion-conductive rubber is less than the above range or exceeds the above range, the roller resistance value of the developing roller may not be adjusted to a range suitable for the developing roller.

On the other hand, if the ratio of the ion-conductive rubber exceeds the above range, the ratio of the diene rubber becomes relatively small, and the roller main body cannot be provided with the above-mentioned good characteristics as a rubber. In some cases.
On the other hand, by setting the proportion of the ion-conductive rubber within the above range, it is possible to impart favorable characteristics as rubber to the roller body while adjusting the roller resistance value of the developing roller within a suitable range. .

<Crosslinking component>
As the cross-linking component, it is preferable to use a cross-linking agent for cross-linking the rubber together with a cross-linking accelerator for promoting the cross-linking of the rubber by the cross-linking agent.
Examples of cross-linking agents include sulfur-based cross-linking agents, thiourea-based cross-linking agents, triazine derivative-based cross-linking agents, peroxide-based cross-linking agents, and various monomers, with sulfur-based cross-linking agents being particularly preferred.

(Sulfur-based cross-linking agent)
Examples of sulfur-based cross-linking agents include sulfur such as powdered sulfur, oil-treated powdered sulfur, precipitated sulfur, colloidal sulfur, dispersible sulfur, or organic sulfur-containing compounds such as tetramethylthiuram disulfide and N,N-dithiobismorpholine. etc., and sulfur is particularly preferred.
The proportion of sulfur is preferably 0.5 parts by mass or more, and preferably 2 parts by mass or less per 100 parts by mass of the total amount of rubber, in consideration of imparting good rubber properties to the roller body. preferable.

For example, when oil-processed powdery sulfur, dispersible sulfur, or the like is used 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 for promoting cross-linking of rubber include thiuram-based accelerators, thiazole-based accelerators, thiourea-based accelerators, guanidine-based accelerators, sulfenamide-based accelerators, dithiocarbamate-based accelerators, and the like. 1 type or 2 types or more are mentioned.
Among these, thiuram accelerators, thiazole accelerators, thiourea accelerators, and guanidine accelerators are preferably used in combination.

Thiuram-based accelerators include, for example, one or more of tetramethylthiuram monosulfide, tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, dipentamethylenethiuram tetrasulfide, and the like. Thiuram monosulfide is preferred.
Thiazole accelerators include, for example, 2-mercaptobenzothiazole, di-2-benzothiazolyl disulfide, zinc salt of 2-mercaptobenzothiazole, cyclohexylamine salt of 2-mercaptobenzothiazole, 2-(4'- morpholinodithio)benzothiazole and the like, and di-2-benzothiazolyl disulfide is particularly preferred.

As the thiourea accelerator, various thiourea compounds having a thiourea structure in the molecule can be used.
Thiourea-based accelerators include, for example, ethylenethiourea, N,N'-diphenylthiourea, trimethylthiourea, formula (2):
( _CnH2n+ 1NH) _{2C =} S (2)
[In the formula, n represents an integer of 1 to 12. ], tetramethylthiourea and the like, and ethylenethiourea is particularly preferred.

Guanidine-based accelerators include, for example, one or more of 1,3-diphenylguanidine, 1,3-di-o-tolylguanidine, 1-o-tolylbiguanide and the like, particularly 1,3- Di-o-tolylguanidine is preferred.
In the combined system of the above four types, considering the effect of promoting cross-linking of the rubber sufficiently, the ratio of the thiuram-based accelerator is 0.3 parts by mass or more per 100 parts by mass of the total rubber. is preferable, and it is preferably 1 part by mass or less.

The ratio of the thiazole-based accelerator is preferably 0.3 parts by mass or more and preferably 2 parts by mass or less per 100 parts by mass of the total rubber.
The ratio of the thiourea-based accelerator is preferably 0.3 parts by mass or more and preferably 1 part by mass or less per 100 parts by mass of the total rubber.
Furthermore, the proportion of the guanidine-based accelerator is preferably 0.2 parts by mass or more and preferably 1 part by mass or less per 100 parts by mass of the total rubber.

The thiourea-based accelerator also functions as an ECO cross-linking agent that does not have sulfur cross-linking properties, and the guanidine-based accelerator also functions as an accelerator for ECO cross-linking by the thiourea-based accelerator.
<others>
Various additives may be added to the rubber composition, if necessary. Examples of additives include cross-linking aids, acid acceptors, fillers, plasticizers, processing aids, and anti-deterioration agents.

Examples of the cross-linking aid include metal compounds such as zinc oxide (zinc white); fatty acids such as stearic acid, oleic acid and cottonseed fatty acid; and one or more of conventionally known cross-linking aids. be done.
The proportion of the cross-linking coagent is preferably 0.1 parts by mass or more and preferably 7 parts by mass or less per 100 parts by mass of the total rubber.

The acid-accepting agent functions to prevent chlorine-based gas generated from epichlorohydrin rubber, CR, etc. during crosslinking from remaining in the roller body, thereby inhibiting crosslinking and contamination of the photoreceptor.
As the acid acceptor, various substances that act as acid acceptors 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 0.2 parts by mass or more, particularly preferably 0.5 parts by mass or more, and preferably 7 parts by mass or less per 100 parts by mass of the total rubber.

Examples of fillers include one or more of zinc oxide, silica, carbon black, talc, calcium carbonate, magnesium carbonate, aluminum hydroxide, and the like.
By blending the filler, the mechanical strength of the roller body can be improved.
Further, by using conductive carbon black as a filler, it is possible to impart electronic conductivity to the roller body.

Examples of conductive carbon black include acetylene black.
The proportion of conductive carbon black is preferably 10 parts by mass or more and preferably 30 parts by mass or less per 100 parts by mass of the total amount of rubber.
Examples of plasticizers include various plasticizers such as dibutyl phthalate, dioctyl phthalate, and tricresyl phosphate, and various waxes such as polar waxes.

Examples of processing aids include fatty acid metal salts such as zinc stearate.
The proportion of plasticizers and/or processing aids is preferably no more than 3 parts by weight per 100 parts by weight of total rubber.
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 developing roller on the environment and suppresses the increase in the roller resistance value during continuous energization.
Anti-aging agents include, for example, nickel diethyldithiocarbamate, nickel dibutyldithiocarbamate and the like.
The proportion of the anti-aging agent is preferably 0.1 part by mass or more and preferably 1 part by mass or less per 100 parts by mass of the total rubber.

As additives, various additives such as anti-scorch agents, lubricants, pigments, antistatic agents, flame retardants, neutralizing agents, nucleating agents and co-crosslinking agents may be blended in arbitrary proportions.
In the examples of FIGS. 1(a) to 1(c), the roller body 2 has a single-layer structure, but the roller body may have a laminated structure of two or more layers.
In that case, the above-described hardened region may be formed at the edge of the outermost layer that constitutes the laminated structure.

The developing roller 1 of the present invention can be used, for example, in image forming apparatuses using electrophotography, such as laser printers, electrostatic copiers, plain paper facsimile machines, and multifunction machines thereof.

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)
As the rubber, GECO [Epion (registered trademark) 301 manufactured by Osaka Soda Co., Ltd., EO/EP/AGE=73/23/4 (molar ratio)] 20 parts by mass, BR [BR01 manufactured by JSR Corporation, Cis-1,4 bond content: 95%, non-oil-extended] 70 parts by mass, and CR [Showprene (registered trademark) WRT manufactured by Showa Denko KK, non-oil-extended] 10 parts by mass were used.

A total of 100 parts by mass of the three kinds of rubbers was masticated using a Banbury mixer, and the following components were first blended and kneaded.

Each component in Table 1 is as follows. Parts by mass in the table are parts by mass per 100 parts by mass of the total amount of rubber.
Conductive carbon black: acetylene black, DENKA BLACK (registered trademark) granular product manufactured by Denka Co., Ltd. Cross-linking aid: Zinc oxide type 2, manufactured by Mitsui Mining & Smelting Co., Ltd. Then, while continuing kneading, the following cross-linking components were added. A rubber composition was prepared by blending and further kneading.

Each component in Table 2 is as follows. Parts by mass in the table are parts by mass per 100 parts by mass of the total amount of rubber.
Cross-linking agent: Kinkajirushi 5% oil-containing fine sulfur powder manufactured by Tsurumi Chemical Industry Co., Ltd. Accelerator TS: Tetramethylthiuram monosulfide, Sancera (registered trademark) TS manufactured by Sanshin Chemical Industry Co., Ltd., thiuram-based accelerator Agent DM: di-2-benzothiazolyl disulfide, Accel (registered trademark) DM manufactured by Kawaguchi Chemical Industry Co., Ltd., thiazole-based accelerator Accelerator 22: ethylene thiourea, 2-mercaptoimidazoline, Kawaguchi Chemical Industry Co., Ltd. Axel 22-S made by
Accelerator DT: 1,3-di-o-tolylguanidine, Suncellar DT manufactured by Sanshin Chemical Industry Co., Ltd., guanidine-based accelerator (production of developing roller)
The prepared rubber composition was supplied to an extruder and extruded into a cylindrical shape having an outer diameter of φ20 mm and an inner diameter of φ7 mm. .

Next, the crosslinked cylindrical body was reattached to a metal shaft having an outer diameter of φ7.5 mm, the outer peripheral surface of which was coated with a conductive thermosetting adhesive (polyamide), and heated to 160°C in an oven. It was heated and adhered to the metal shaft.
Next, both ends were shaped, and the outer peripheral surface was traverse-polished using a cylindrical polisher, and then mirror-polished using a #2000 lapping film [mirror film manufactured by Sankyo Rikagaku Co., Ltd.] to an outer diameter of φ20.00 mm. (Tolerance 0.05).

After the polishing, the roller body is washed with water and dried, and then each end of the roller body in the axial direction is individually immersed in a treatment liquid containing an isocyanate group-containing silane compound at a temperature of 23±1°C. , the treatment liquid was impregnated into the end portion from the outer peripheral surface of the end portion of the roller body.
As the treatment liquid, a stock solution of methyltriisocyanatesilane [Orgatics (registered trademark) SI-310 manufactured by Matsumoto Fine Chemicals Co., Ltd.] in which R ¹ in formula (1) is a methyl group was used.

After immersion for 30 minutes, the end of the roller body was pulled up from the treatment liquid, and excess treatment liquid adhering to the outer peripheral surface of the end was wiped off with a wiper [Cupra (registered trademark) continuous filament nonwoven fabric as a base fabric. BENCOT (registered trademark) manufactured by Asahi Kasei Corporation].
Then, it was allowed to stand for 24 hours in an environment of a temperature of 23±1° C. and a relative humidity of 55±1%, and the isocyanate group-containing silane compound impregnated in the edge was allowed to undergo a curing reaction to form a cured region in the edge.

Next, the ends where the cured regions are formed are covered with a mask, and the roller body is set in an ultraviolet treatment device [PL21-200 manufactured by Sen Special Light Source Co., Ltd.] with the intermediate portion between the ends exposed. did.
Then, while rotating the roller body by 90° around the shaft, ultraviolet rays with wavelengths of 184.9 nm and 253.7 nm are irradiated for 15 minutes each, thereby forming an oxide film on the outer peripheral surface of the intermediate portion and developing. manufactured rollers.

<Example 2>
Development was carried out in the same manner as in Example 1, except that the undiluted solution of tetraisocyanate silane [Orgatics SI-400 manufactured by Matsumoto Fine Chemicals Co., Ltd.] in which R ¹ in formula (1) is an isocyanate group was used as the processing solution. manufactured rollers.
<Example 3>
A developing roller was manufactured in the same manner as in Example 2, except that the step of irradiating the intermediate portion with ultraviolet rays was omitted and no oxide film was formed on the intermediate portion.

<Example 4>
As the treatment liquid, a solution of the same tetraisocyanate silane [Orgatics SI-400 manufactured by Matsumoto Fine Chemical Co., Ltd.] as used in Example 2 and toluene at a mass ratio of 1:1 was used. A developing roller was manufactured in the same manner as in Example 1, except that the two ends in the axial direction were individually immersed in the above treatment liquid for 5 minutes.

<Comparative Example 1>
A developing roller of Comparative Example 1 was obtained by polishing the outer peripheral surface of the roller body in Example 1 and rinsing it with water, and then forming neither a hardened region at the end portion nor an oxide film in the intermediate portion.
<Comparative Example 2>
The developing roller of Comparative Example 2 was obtained by polishing the outer peripheral surface of the roller body in Example 1 and rinsing it with water, and then forming an oxide film on the entire outer peripheral surface of the roller body without forming hardened regions at the ends. did.

<Comparative Example 3>
As the treatment liquid, a solution of carbodiimide-modified diphenylmethane diisocyanate [carbodiimide-modified MDI, manufactured by BASF INOAC Polyurethane Co., Ltd., Lupranate (registered trademark) MM-103], which is an aromatic diisocyanate compound, and toluene at a mass ratio of 1:1 is used. A developing roller was manufactured in the same manner as in Example 1, except that

<Comparative Example 4>
Example 1 except that a solution of unmodified MDI (pure MDI, Lupranate MS manufactured by BASF INOAC Polyurethane Co., Ltd.), which is an aromatic diisocyanate compound, and toluene at a mass ratio of 1:1 was used as the treatment liquid. A developing roller was manufactured in the same manner.
<Friction test>
The dynamic friction coefficients of the developing rollers produced in Examples and Comparative Examples were measured using a Handy Tribomaster TL201Ts manufactured by Trinity Lab Co., Ltd. under an environment of a temperature of 23±1° C. and a relative humidity of 55±1%. Measurement was performed under the following conditions: contactor, load: 10 g, measurement distance: 10 mm, moving speed: 10 mm/sec.

<Actual machine test>
Genuine new cartridge [TN-56J manufactured by Brother Industries, Ltd.], which is equipped with a toner container containing toner, a photoreceptor, and a developing roller in contact with the photoreceptor, and which can be attached to and detached from the main body of a laser printer. The developing rollers manufactured in Examples and Comparative Examples were incorporated instead of the developing rollers of the above.

Next, the above cartridge was loaded into a laser printer [HL-6180DW manufactured by Brother Industries, Ltd.], and 6000 images of 5% density were printed on plain paper in an environment of a temperature of 23±1° C. and a relative humidity of 55±1%. After the sheets were continuously formed, leakage of toner around the cartridge was confirmed, and the developing roller was taken out from the cartridge to observe the end portion of the roller body.
Then, the state of wear of the roller body was evaluated according to the following criteria.

⊚: The edge of the roller body was not worn at all, and toner leakage was not observed.
Good: The end of the roller body was slightly worn, but no toner leakage was observed.
x: The end of the roller body was worn, and toner leakage was observed.
Tables 3 and 4 show the above results.

From the results of Examples 1 to 4 and Comparative Examples 1 to 4 in Tables 3 and 4, a cured region was formed by forming a cured region containing an isocyanate group-containing silane compound at the end of the roller body of the developing roller. Friction on the outer peripheral surface of the roller body can be greatly reduced compared to the case where the curing area is not formed or the case where the cured region is formed of an aromatic diisocyanate compound, and wear of the end portion of the roller body and accompanying toner leakage are both reduced. It was found to be well suppressed.

Further, from the results of Examples 1 to 3, considering the further reduction of surface friction, it is preferable to use tetraisocyanate silane as the isocyanate group-containing silane compound, and that an oxide film is formed in the middle part of the roller body. was found to be preferable.
Furthermore, from the results of Examples 2 and 4, even if the impregnation time is shortened, the end portion of the roller body is quickly impregnated, thereby forming a better cured region and improving the productivity of the developing roller. Taking this into account, it has been found that it is preferable to use a solution of a silane compound containing an isocyanate group as the treatment liquid.

Reference Signs List 1 developing roller 2 roller main body 2a end portion 2b intermediate portion 21 hardened region 22 non-impregnated region 3 through hole 4 shaft 5 outer peripheral surface 6 oxide film

Claims (5)

A cylindrical roller body made of a crosslinked rubber composition is provided at both ends in the axial direction of the roller body radially inward of and in the vicinity of the outer peripheral surface of the roller body. , a crosslinked product of the rubber composition and a cured product of an isocyanate group-containing silane compound, including a cured region exposed on the outer peripheral surface, and an intermediate portion between the both ends of the roller body, the above A developing roller comprising only a crosslinked product of a rubber composition that does not contain a cured product of an isocyanate group-containing silane compound . 2. The developing roller according to claim 1, wherein the roller body includes an oxide film made of an oxide of a crosslinked product of the rubber composition on at least the outer peripheral surface other than the end portions. 3. The developing roller according to claim 1, wherein the isocyanate group-containing silane compound is tetraisocyanate silane. 4. The method for manufacturing the developing roller according to any one of claims 1 to 3, comprising: forming the rubber composition into a cylindrical shape and cross-linking to form the roller body; A treatment liquid containing at least the isocyanate group-containing silane compound is supplied to the outer peripheral surfaces of the both ends , and the treatment liquid is selectively directed radially inward of the both ends from the outer peripheral surfaces. and curing reaction of the isocyanate group-containing silane compound in the impregnated treatment liquid, the intermediate portion between the both ends of the roller body is a cured product of the isocyanate group-containing silane compound. While formed only by the crosslinked product of the rubber composition that does not contain the crosslinked product of the rubber composition, and A method for producing a developing roller, comprising a step of forming the cured region exposed on the outer peripheral surface, the developing roller containing a cured product of the isocyanate group-containing silane compound. 4. A step of irradiating an outer peripheral surface of said roller body at least other than said end portion with ultraviolet rays to form an oxide film made of an oxide of a crosslinked product of said rubber composition on said outer peripheral surface. 3. The method of manufacturing the developing roller according to .

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