JP2649161B2 - Manufacturing method of conductive roll - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a conductive roll used as a charging roll, a developing roll, a cleaning roll and the like of an electrophotographic copying machine.

[Conventional technology]

A conductive roll used for a charging roll of an electrophotographic machine or the like is required to have a conductivity within a range of about 10 ¹ to 10 ¹² Ω, and usually, as shown in FIG. And a conductive elastic layer 2 formed on the outer peripheral surface thereof. The conductive elastic layer 2 generally includes
It is formed of a composition in which conductive powder and conductive fibers (carbon black, metal powder, carbon fibers, etc.) are mixed in synthetic rubber such as silicone rubber. Also, instead of the conductive elastic layer 2, an ionic semiconducting material utilizing the inherent ionic conductivity of synthetic rubber, or adding a high dielectric liquid or an ionic substance thereto to reinforce the ionic conductivity of the synthetic rubber. A conductive roll provided with a conductive elastic layer is also known.

In order for such a conductive roll to perform a sufficient function in applications such as charging, developing, cleaning, and transfer, the electric resistance level must be 10 ¹ to 10 ¹² as described above.
It is said that it is desirable to be in the range of Ω. And
In particular, when used as a charging roll, as shown in FIG. 4, the charging rolls 3 and 3a are pressed against the outer peripheral surface of the photosensitive drum 4 and rotated.
In order to charge the outer peripheral surface of the charging roll, it is required that the charging roll has elasticity and at the same time, its electric resistance level does not fluctuate due to elastic deformation. It is said that the electric resistance level of such a charging roll is desirably in the range of 10 ⁵ to 10 ⁸ Ω. In FIG. 4, reference numeral 5 denotes toner adhered to the surface of the photosensitive drum 4, and shows a state in which the photosensitive drum 4 is charged on the cathode and the toner 5 is charged on the anode. Reference numeral 6 denotes a copy sheet for receiving a supply of the toner 5 from the photosensitive drum 4 to form a copy image.

[Problems to be solved by the invention]

However, since the conductive roll provided with the conductive elastic layer 2 is provided with conductivity by the contact between the conductive particles mixed in the synthetic rubber, uniform contact between particles cannot always be obtained. This is particularly noticeable in the semiconductive region, and it is therefore difficult to keep the conductivity within the above range. Further, when the hardness of the synthetic rubber serving as the matrix is low (for example, in the case of a foam), the conductive elastic layer 2 is easily deformed by pressurization, so that the degree of contact between the conductive particles changes and the electric resistance increases. Change. Therefore, due to the non-uniformity of the conductivity and the change of the electric resistance, the charging and the like of the photosensitive drum become non-uniform, and a satisfactory image quality cannot be obtained in an electrophotographic copying machine or the like.

Also, when utilizing the inherent ionic conductivity of synthetic rubber,
It is difficult to keep the electric resistance level within the range of 10 ⁵ to 10 ⁸ Ω, and it is conceivable to add a high dielectric liquid or ionic substance to lower the electric resistance level,
This causes a problem such as contamination of the photoconductor. In particular, when an organic photoreceptor is used as the photoreceptor, the high dielectric liquid may dissolve the photoreceptor.

On the other hand, a method for producing a toner charging roll in which a methoxymethylated nylon layer is directly provided on the outer peripheral surface of a metal sleeve is disclosed (Japanese Patent Application Laid-Open No. 56-89766). But,
According to this method, the nylon layer is directly provided on the outer peripheral surface of the smooth metal sleeve, and the nylon layer is not provided via the elastic layer. Then, it is considered that the metal sleeve is immersed only once with the metal sleeve lying on its side. However, even in this case, an elastic layer is formed on the outer peripheral surface, and the elastic layer is not as smooth as the surface of the metal sleeve.
The conductive nylon layer cannot be formed uniformly.

Thus, all of the conventional conductive rolls are
There have been problems such as non-uniform conductivity and contamination of the photoreceptor, and in fact, satisfactory products have not been obtained.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a method for manufacturing a conductive roll of excellent quality, which has a uniform conductivity and does not cause a risk of contamination of the photosensitive member.

[Means for solving the problem]

In order to achieve the above object, a method of manufacturing a conductive roll of the present invention includes preparing a metal shaft having a conductive elastic layer formed on an outer peripheral surface thereof, preparing a solvent solution of N-methylmethoxylated nylon, In a state where the metal shaft is vertical, the immersion and pull-up are repeatedly performed in the N-methylmethoxylated nylon solvent solution, and the N-methylmethoxylated nylon solvent solution is formed on the conductive elastic layer on the outer periphery of the metal shaft. A liquid film is formed, and then a solvent is volatilized from the liquid film through a drying step to form a conductive resin layer made of N-methylmethoxylated nylon.

[Action]

That is, to obtain a conductive roll having uniform conductivity and no risk of contamination of the photoreceptor, the present inventors do not simply mix a conductive substance with an elastic body such as synthetic rubber or the like. When the conductive resin layer is formed from a resin liquid having a conductive property and physical properties such as elasticity and abrasion resistance exhibiting appropriate values, the conductive resin layer formed uniformly can be used. The idea was that the conductivity would be uniform, so that the conductivity would be uniform. As a result of a series of studies on resins having such properties, N-
Methylmethoxylated nylon has been found to be suitable. However, simply forming the conductive resin layer made of nylon on an elastic layer having no smoothness such as the surface of a metal sleeve by a simple immersion method does not make the conductivity uniform. . Then, the present inventors have devised the immersion method and arrived at the present invention. In the present invention, “mainly” is used to include a case where the conductive resin composition is composed of only the N-methylmethoxylated nylon.

 Next, the present invention will be described in detail.

The conductive roll obtained according to the present invention has a conductive elastic layer 12a formed on an outer peripheral surface of a metal shaft 10 via an adhesive layer (not shown), as shown in FIG. And a conductive resin layer 11 formed thereon.

The conductive roll is obtained, for example, as follows. That is, first, an elastic body such as synthetic rubber containing a conductive substance such as conductive carbon is spread around the outer periphery of the metal shaft 10 that has been subjected to the adhesive treatment, and then vulcanized in a mold and then polished to form the conductive elastic layer 12a. Let it. On the other hand, N-methylmethoxylated nylon is dissolved in a solvent such as a mixed solution of methanol and toluene to prepare a resin solution of N-methylmethoxylated nylon. Then, on the outer peripheral surface of the conductive elastic layer 12a of the metal shaft 10, the resin liquid is adhered by immersion, and then
By drying and curing, an intended conductive roll is obtained.

The immersion of the metal shaft 10 in such a resin solution will be described in more detail. A resin solution in which the above-mentioned N-methylmethoxylated nylon is dissolved is stored as a dipping solution in a tank 12 as shown in FIG. Metal shaft 10
The resin liquid film is formed on the outer peripheral surface of the conductive elastic layer 12a of the metal shaft 10 by standing vertically and repeatedly immersed in the resin liquid in the tank 12. At this time, the conditions such as the elevating speed, the number of elevating and lowering times, and the drying time are as follows.
It is preferable to set the optimum conditions so as to fall within the range of 500 μm. Then, by drying this under predetermined conditions, the solvent is removed and the resin liquid film is cured, whereby the conductive resin layer 11 can be obtained.

In the conductive resin layer 11 thus obtained, since the N-methylmethoxylated nylon, which is the conductive resin, is uniformly distributed, the conductivity is not unevenly distributed depending on the place. As a result, uniform conductivity is obtained.

The N-methylmethoxylated nylon used in the present invention is:
A resin having the following repeating units, in which hydrogen bonded to nitrogen is partially substituted with a methylmethoxy group in an amide bond portion of a normal nylon resin, and is usually referred to as "8-nylon". . The electric resistance is 10 ⁶ -10 ¹⁰ Ω · cm.

The hardness of the N-methylmethoxylated nylon decreases as the degree of methylmethoxylation (hereinafter abbreviated as “MM degree”) increases. Preferably, the degree is in the range of 20-40%. That is, when the degree of M / M conversion is less than 20%, the hardness of the conductive resin layer 11 obtained is too high, and the partner is worn out early in rubbing with the photoreceptor, etc., resulting in slipping or scratching. Is not preferred. Conversely, if the degree of M · M exceeds 40%, the hardness of the conductive resin layer 11 to be obtained is too low, so that the conductive resin layer 11 itself wears quickly and is not practical.

In addition, it is preferable that the MM degree is particularly around 30% in the above range.

Examples of the solvent for dissolving the N-methylmethoxylated nylon include a mixed solvent of methanol (M) and toluene (T) (mixing ratio M / T = 7/3) or a mixed solvent of methanol and water (mixing ratio M / water). = 8/2), methanol and ethanol (E)
(Mixing ratio M / E = 3/1).

The conductive resin layer of the conductive roll thus obtained
In FIG. 11 (see FIG. 1), N-methylmethoxylated nylon, which is a semiconductive resin, is dispersed in a uniform state, and shows uniform conductivity at any location.

The conductive resin layer 11 in the obtained conductive roll was used.
Has an electrical resistance in the range of 10 ⁵ to 10 ⁸ Ω, and exhibits sufficient performance even when used as a charging roll with particularly demanding electrical characteristics.

The conductivity can be further enhanced by adding conductive material particles such as metal powder, which has been conventionally used, to the conductive resin layer 11.

Furthermore, nylon particles may be added to the conductive resin layer 11 to make the surface rough. In other words, when the conductive roll is used on the premise of rubbing like a charging roll or the like, if the surface of the conductive resin layer 11 is close to a mirror surface, the friction increases and the burden increases.
Therefore, when nylon particles are added to the conductive resin layer 11 and irregularities due to the nylon particles are imparted to the surface, the conductive roll and the rubbing partner are dispersed in point contact with each other when rubbing with the photoreceptor or the like. Has an effect that the mutual burden is reduced. As the nylon particles, a particle diameter of 10 to 300
From the viewpoint of the effect, it is preferable to use particles of μm having an electric resistance level of 10 ⁵ Ω · cm or more. The amount of addition is preferably set to 2% by volume or more of the conductive resin layer 11, particularly 5% by volume or more. In addition, the particle shape of the above nylon particles is spherical, flat, cylindrical, etc.
Any shape is acceptable. Conductive resin layer 11
This is because it is sufficient to provide irregularities on the surface.

The conductive rolls obtained as described above can be appropriately used depending on the application such as charging, development, transfer, and cleaning.

 Next, examples will be described together with comparative examples.

Example 1 A conductive roll (metal shaft 10+) having the structure shown in FIG.
The conductive elastic layer 12a + conductive resin layer 11) was specifically manufactured, and the function as a charging roll was evaluated.

That is, first, N-methoxymethylated nylon (M.
30% M degree, Tresin EF-30T, Teikoku Chemical Sangyo)
It was dissolved in a mixed solvent of methanol / toluene (former / latter = 7/3) to obtain a N-methylmethoxylated nylon resin habit. This resin solution was poured into a dipping tank (see FIG. 2) as a dipping solution after adjusting the viscosity. On the other hand, the shaft diameter is 8φ
Of metal Shaft prepared to form a conductive elastic layer polynorbornene rubber compositions containing conductive carbon to the outer periphery (hardness 20 °, the electric resistance 10 ³ Ω · cm) wound. The thickness of the conductive elastic layer was 3 mm. Then, the metal shaft with the conductive elastic layer was set vertically, and was repeatedly immersed in the previously prepared tank containing the resin liquid, coated with the resin liquid, and air-dried at room temperature. Subsequently, the solvent was removed by heating at 60 to 80 ° C. for 0.5 to 3 hours to form a conductive resin layer. The thickness of this conductive resin layer was 100 μm. Thus, the desired conductive roll was obtained.

[Examples 2 to 5] N-methylmethoxylated nylons having different M and M degrees (see the table below) were used. Otherwise in the same manner as in Example 1, the intended conductive roll was obtained.

[Comparative Example 1] A metal shaft was coated with a rubber in which carbon black was blended with EPDM, and after vulcanization in a mold, polishing was performed to obtain a conductive roll having a structure as shown in FIG.

Comparative Example 2 NBR containing TPXP (tributoxyethyl phosphate) was used in place of the EPDM containing carbon black. Otherwise in the same manner as in Comparative Example 1, a conductive roll was obtained.

[Comparative Example 3] In Example 2, the metal shaft with the conductive elastic layer was
It was immersed repeatedly in the resin liquid horizontally, and the resin liquid was coated. Otherwise, in the same manner as in Example 2, a conductive roll was obtained.

For each of the conductive rolls thus obtained, 25
In order to measure the electrical resistance under 60 ℃ and 60% RH, and to evaluate the variation of electrical resistance, draw a 10mm square electrode with silver paste (with a guard electrode) on five places on the outer surface of the conductive roll, and use a metal shaft. And the resistance between the electrodes. Further, these conductive rolls were used as charging rolls in an actual electrophotographic copying machine, and whether or not the organic photoreceptor layer was contaminated was observed and its durability was examined.

 The results are shown in the table below.

From the above results, it can be seen that all of the products of the examples have a small variation in resistance, and show excellent durability without photoconductor contamination. On the other hand, it can be seen that the products of Comparative Examples 1 and 3 have a large resistance variation, and the product of Comparative Example 2 has contamination of the photoconductor, which is not preferable as a charging roll.

〔The invention's effect〕

As described above, the present invention provides the above-described N-shape in a state where the metal shaft having the conductive elastic layer formed on the outer peripheral surface is vertical.
In a methylmethoxylated nylon solvent solution, repeated immersion and pulling up, a liquid film made of an N-methylmethoxylated nylon solvent solution is formed on the conductive elastic layer on the outer periphery of the metal shaft, and then passed through a drying step. The solvent is volatilized from the liquid film to form a conductive resin layer made of N-methylmethoxylated nylon, so that an excellent conductive roll having uniform conductivity and not contaminating the photoreceptor is formed by a special method. It can be easily manufactured using a conventional device without using a device.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a conductive roll obtained by the present invention, FIG. 2 is an explanatory view for explaining a method for forming a conductive resin layer of the present invention, and FIG. FIG. 4 is a vertical sectional view showing a conductive roll, and FIG. 4 is a schematic explanatory view for explaining the function of a charging roll in a general electrophotographic copying machine. 10: Metal shaft, 11: Conductive resin layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroyasu Kato 3600 Gezu, Kita-gaiyama, Komaki-shi, Aichi Tokai Rubber Industries Co., Ltd. Tokai Rubber Industries, Ltd. (56) References JP-A-56-89766 (JP, A)

Claims (2)

(57) [Claims] 1. A metal shaft having a conductive elastic layer formed on an outer peripheral surface thereof is prepared, and a solvent solution of N-methylmethoxylated nylon is prepared. In a methoxylated nylon solvent solution, repeatedly dipped and pulled up, on the conductive elastic layer on the outer periphery of the metal shaft, to form a liquid film composed of an N-methyl methoxylated nylon solvent solution, and then through a drying step A method for producing a conductive roll, comprising: evaporating a solvent from the liquid film to form a conductive resin layer made of N-methylmethoxylated nylon. 2. The method according to claim 1, wherein the thickness of the liquid film is 10 to 500 μm.