JPH05100549A - Semiconductive foamed body roll - Google Patents

Abstract

PURPOSE:To obtain a semiconductive foamed body roll stabilized in electric resistance and capable of obtaining a uniform nip width by using a specified high molecular compd. as a matrix and incorporating a specified amt. of a perchlorate as a conductive material. CONSTITUTION:This semiconductive foamed body roll is formed with a metallic shaft 5 and a semiconductive polymer layer 6 formed on the shaft. The polymer layer 6 is formed with the semiconductive foamed polymer composition contg. a high molecular compd., a perchlorate and a foaming agent. The high molecular compd. should have an ether linkage in the repeating unit. The amt. of the perchlorate to be mixed is controlled to 0.05-20 pts.wt. based on 100 pts.wt. of the high molecular compd. At <0.05 pts.wt., the electric resistance is not substantially lowered. At >20 pts.wt., the electric resistance is not lowered, the polymer layer becomes brittle, and the durability is deteriorated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductive foam roll used in electrophotographic copying machines, printers and the like.

[0002]

2. Description of the Related Art Rolls such as a charging roll, a developing roll and a transfer roll of an electrophotographic copying machine, which require control of electric resistance in a medium resistance region, generally have a shaft body as shown in FIG. 1 has a single-layer structure in which a semi-conductive polymer layer 2 is formed on the outer circumference of the shaft 1. Alternatively, as shown in FIG. Formed, and the semiconductive polymer layer 2 is formed on the outer periphery thereof 2
Take a layered structure.

In these rolls having a single-layer structure or a two-layer structure, the semiconductive polymer layer 2 has a polymer composition in which a conductive material such as carbon is dispersed and contained in a solid polymer composition, and an interface. Polymer compositions containing an antistatic agent containing an activator as a main component are used. The semiconductive polymer layer 2 has a property that its volume hardly changes even when it is pressurized. Therefore, when these rolls are used for the above-mentioned applications, the load is applied to both ends of the roll, so that the contact width (nip width) between the roll and the photosensitive drum is the same as that of the charging roll as the roll end. Different in the central part, it becomes a drum-shaped nip state (non-uniform contact pressure). When this is remarkable, there arises a problem that the central portion does not come into contact with the photosensitive drum. Also, in order to make the roll and the photosensitive drum all contact equally, it is conceivable to use a shaft body (core bar) with a large diameter to increase the load. However, increasing the load in this way reduces the hardness of the roll itself. Even if it is lowered, the contact pressure between the roll and the photosensitive drum rises, causing a problem that the toner is welded to the surface of the photosensitive drum. To solve such problems, for example,
As shown in FIG. 4, it has been studied to use a roll having a single layer structure in which a semiconductive foam polymer layer 4 made of foam is formed on the outer periphery of the shaft body 1. As a material for forming the semiconductive foam polymer layer 4, a polymer composition containing an antistatic agent containing a surfactant as a main component as described above in order to obtain the required semiconductive resistance region. However, it is difficult to satisfy the electric resistance value required in the single-layer structure. On the other hand, as described above, a semiconductive foamed polymer composition in which a conductive material typified by carbon black is added to control the electric resistance value has been investigated as a suitable one.

[0004]

However, the roll in which the semiconductive foam polymer layer is formed by the above-mentioned forming material using the carbon black or the like as a conductive material is such that the electric resistance of the carbon black or the like is dispersed in the matrix. Since it depends on the distance between the conductive material particles, there is a problem that it is particularly difficult to control the foam. In addition, since the distance between the conductive material particles changes depending on whether the particles are compressed or not, there is a problem that the electric resistance changes. Further, there is a problem in that the connection between the conductive material particles is cut by repeated compression deformation during use, and the electric resistance changes during use.

The present invention has been made in view of the above circumstances, and it is easy to control the electric resistance, the compression resistance and the electric resistance during use are stable, and a uniform nip width can be obtained at a low contact pressure. It is an object of the present invention to provide a semiconductive foam roll that is used.

[0006]

In order to achieve the above object, the semiconductive foam roll of the present invention is a semiconductive foam in which a semiconductive foam polymer layer is formed on the outer periphery of a shaft body. In the roll, the semiconductive foam polymer layer has a polymer compound having an ether bond in a repeating unit as a matrix component, and contains the matrix component, perchlorate and a foaming agent, and the matrix component. 10
The semiconductive foamable polymer composition contains 0.05 to 20 parts by weight of perchlorate with respect to 0 parts by weight.

[0007]

That is, the present inventors have conducted a series of studies in order to obtain a semiconductive foam roll having stable electric resistance and a uniform nip width. As a result, a polymer compound having an ether bond in the repeating unit was used as a matrix, and when a specific amount of ionic conductive perchlorate was used as a conductive material in this matrix, the perchlorate was converted into a matrix. The present invention has been accomplished by finding that a conductive ionic substance is formed due to coordination with an ether bond portion in the inside, and that a substance having stable electric resistance can be obtained.

Next, the present invention will be described in detail.

The semiconductive foam roll of the present invention comprises a shaft and a semiconductive foam polymer layer formed on the outer periphery of the shaft.

The shaft body is not particularly limited, and a cored bar made of a solid metal body or a metal cylindrical body having a hollow hollow inside is used.

The semiconductive foamed polymer layer is formed of a semiconductive foamable polymer composition containing a specific polymer compound, a perchlorate and a foaming agent.

The above-mentioned specific polymer compound must have an ether bond in the repeating unit. Specific examples thereof include polyethylene oxide, polypropylene oxide, epichlorohydrin-ethylene oxide copolymer rubber and urethane rubber, which may be used alone or in combination. Of these, in consideration of foaming, it is preferable to use epichlorohydrin-ethylene oxide copolymer rubber or urethane rubber.

Examples of the perchlorate include potassium perchlorate, sodium perchlorate, and quaternary ammonium perchlorate such as octadecyltrimethylammonium perchlorate. These may be used alone or in combination.

The amount of the perchlorate compounded is 100 parts by weight of the specific polymer compound (hereinafter abbreviated as "part").
It is necessary to set it to 0.05 to 20 parts. That is, if the amount of the perchlorate compounded is less than 0.05 parts, the effect of lowering the electric resistance is not substantially obtained, and the electric resistance is equivalent to the electric resistance of the matrix component,
On the other hand, if it exceeds 20 parts, not only the effect of lowering the electric resistance cannot be obtained, but also the obtained polymer layer becomes brittle and the durability is deteriorated.

The above-mentioned foaming agent is not particularly limited and may be a conventionally known one. For example, when the polymer compound is epichlorohydrin-ethylene oxide copolymer rubber, diazoaminobenzene, dinitrosopentamethylenetetramine, Examples thereof include benzolsulfonyl hydrazide. These may be used alone or in combination. The blending amount of these foaming agents is preferably set to 2 to 10 parts.

In addition to the above-mentioned components, a conductive agent, a foaming aid, a cross-linking agent, an antiaging agent, etc. may be appropriately added to the above semiconductive foamable polymer composition. You can

The semiconductive foam roll of the present invention is obtained, for example, as follows. That is, first, a specific polymer compound as a matrix component, a perchlorate, a foaming agent and, if necessary, other additives are mixed and sufficiently kneaded to prepare a semiconductive foamable polymer composition. Then, this semiconductive foamable polymer composition is extrusion-molded and coated on the outer periphery of a metal shaft (shaft) having an adhesive applied to the outer periphery,
It is obtained by heat foaming and crosslinking in a mold. Also,
It can also be obtained by extruding a foam tube, heat-foaming and crosslinking the foam tube, and then inserting a metal shaft into the foam-crosslinked foam tube. The semiconductive foam roll thus obtained is shown in FIG. In the figure, 5 is a metal shaft (shaft), and 6 is a semiconductive foam polymer layer.

Further, a solvent which is soluble in perchlorate and which permeates the matrix component is used to dissolve the perchlorate, and the foam tube formed by extrusion molding is treated with the above-mentioned perchlorate. Immerse in acid salt solution. And
It is also possible to impregnate the foam tube with perchlorate to produce a semiconductive foam roll. Even if the perchlorate is impregnated in this way, the same effect as in the above kneading process can be obtained.

In the semiconductive foam roll thus obtained, in the semiconductive foam polymer layer 2, the perchlorate salt is coordinate-bonded with the ether bond in the matrix to show ionic conductivity. The roll is semi-conductive (10 ⁵ -10
⁷ Ω).

[0020]

As described above, in the semiconductive foam roll of the present invention, the semiconductive foam polymer layer uses a polymer compound having an ether bond in the repeating unit as a matrix. It is formed of a semiconductive foamable polymer composition in which a perchlorate having ionic conductivity is used as a conductive material in a specific amount. For this reason, the semiconductive foam polymer layer is not electronically conductive as in the case of using conventional carbon black, but is electrically conductive due to ionic conductivity in which perchlorate is coordinate-bonded to the ether bond part in the matrix. Has been done. Therefore, stable electric resistance can be obtained even during compression deformation of the roll and during use, and further, a low hardness and a uniform nip width can be obtained.

Next, examples will be described together with comparative examples.

[0022]

Examples 1 to 6 and Comparative Examples 1 to 4 Tables 1 and 2 below.
The raw materials shown in Table 1 were blended in the proportions shown in the same table, and kneaded using a Banbury mixer and a roll, which are ordinary rubber kneading equipment, to prepare an unvulcanized rubber composition. Then, the above-mentioned unvulcanized rubber composition was charged into an extruder and extruded in a tube shape, and this was heat-treated in an oven at 150 ° C. for 40 minutes to foam and vulcanize to prepare a foam tube. .. Then, this foam tube is inserted into a core metal (diameter 6 mm) whose outer peripheral surface is coated with a conductive adhesive, and the surface of the foam tube is ground to a predetermined size to obtain a target outer diameter of 12 mm. A semiconductive foam roll was obtained.

[0023]

[Table 1]

[0024]

[Table 2]

[0025]

[Comparative Example 5] A conductive rubber composition containing ethylene-propylene-diene rubber and carbon black as main components, adjusted to have an electric resistance of 10 ⁶ Ω · cm at JIS hardness of 25 ° without using a foaming agent was used. A semiconductive non-foamed roll was obtained by the same method as in Example 1 above.

The semi-conductive foam roll thus obtained was measured and evaluated for its nip shape, electric resistance value, durability, hardness and appearance after durability test. The results are shown in Tables 3 and 4 below.

The nip shape is such that a smooth and thick glass plate is provided with semiconductive foam rolls at both ends of which 500
The width of the contact portion between the glass plate and the roll when pressed under a load of g was measured at the center and the end. And, if the width of the contact portion between the central portion and the end portion is 40% or more, x,
Those having a difference of 40 to 20% were evaluated as Δ, and those having a difference of 20% or less were evaluated as ◯.

The above electric resistance value is measured when a semiconductive foam roll is pressed on a metal roll having a smooth surface with a diameter of 30 mm and a predetermined load (100 g, 250 g, 500 g) is applied to both ends of the roll. Is the resistance value (voltage 500
V).

With respect to the durability, a semi-conductive foam roll is pressed by applying a load of 500 g to both ends on a metal roll having a diameter of 30 mm and a smooth surface, and the metal roll is rotated at a speed of 20 rpm. Then, the semiconductive foam roll was rotated 100,000 times while being rotated together. Then, according to the measurement of the electric resistance value, a value measured by applying a load of 250 g to both ends is shown.

The appearance after the above durability test was evaluated as × when the appearance was poor and ◯ when the appearance was not significantly changed.

[0031]

[Table 3]

[0032]

[Table 4]

From the results shown in Tables 3 and 4, the products of Comparative Examples show a large change in electric resistance when a load is applied, and inferior durability. On the other hand, in all the example products, the change in electric resistance is small even if a load is applied. From this, it is understood that the example products have stable electric resistance.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a semiconductive foam roll of the present invention.

FIG. 2 is a sectional view of a conventional semiconductive roll.

FIG. 3 is a sectional view of a conventional semiconductive roll.

FIG. 4 is a sectional view of a conventional semiconductive roll.

[Explanation of symbols]

 5 Metal Shaft 6 Semi-Conductive Foam Polymer Layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazunobu Hashimoto 3600 Amagatsu, Kita Sotoyama, Komaki City, Aichi Prefecture Tokai Rubber Industry Co., Ltd. Rubber Industry Co., Ltd.

Claims (1)

[Claims] 1. A semiconductive foam roll having a semiconductive foam polymer layer formed on the outer periphery of a shaft body, wherein the semiconductive foam polymer layer has an ether bond in a repeating unit. A polymer compound as a matrix component, containing the matrix component, a perchlorate and a foaming agent, and further containing 0.05 to 20 parts by weight of the perchlorate with respect to 100 parts by weight of the matrix component. A semiconductive foam roll, which is formed of a conductive foamable polymer composition.