JP3105972B2 - Conductive multilayer tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive multilayer tube having a small change in conductivity (resistivity) due to the environment.

[0002]

2. Description of the Related Art Conventionally, as a conductive elastic roll used as a charging roll of an electrophotographic copying machine, for example, a roll having a conductive elastic layer on at least a surface contains a conductive agent such as carbon. And the like obtained by coating a conductive tube to be used.

[0003] As a charging system, a contact charging system using a charging roll and a corona discharging system using a corona charger without using a charging roll are generally used.

However, the corona discharge method is 5 to 10
There is a problem in operability due to the application of a high voltage of KV, and ozone generated by the discharge has problems in pollution of work environment and sanitation. Further, in terms of performance, there were also disadvantages such as occurrence of charging unevenness and poor charging efficiency. For this reason, at present, the contact charging method is not yet mainstream, but there is a tendency to shift from the corona discharge method to the contact charging method.

[0005]

However, a conventional conductive tube coated with, for example, a charging roll,
When a photoreceptor is charged by a contact charging method, there are many cases where the photoreceptor is not uniformly charged and a clear image or the like cannot be obtained due to a large variation in resistance and a large resistance change due to the environment, and is also blended. Insulation breakdown is likely to occur due to the conductive agent, and a favorable image tends to be difficult to obtain due to a decrease in withstand voltage, bleeding out of the softener from the elastic layer of the roll, and the like.

The inventors of the present invention have conducted various studies to obtain a conductive tube suitable for coating, for example, a roll by using a conductive tube, for example, by solving the above-mentioned problems of a conventional charging roll. The present invention has been reached.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a conductive tube having a multilayer structure composed of two or more layers mainly composed of an organic polymer material, wherein the content of the conductive agent in each layer is changed from the inner surface layer to the surface layer. A multi-layer tube comprising at least two or more layers which are gradually reduced from large to small and blended, wherein the conductivity of the inner surface layer is maximum and the surface layer is minimum. For tubes.

Such a tube has a multilayer structure of at least two or more layers, and the content of the conductive agent in each layer in the film thickness direction varies stepwise, and gradually decreases toward the surface layer. Is desirable. At this time, the total conductive agent content in the tube is 10% by weight to 5%.
It is desirable that the content be 0% by weight, preferably 10% by weight to 30% by weight. If it is out of this range, the effect of the present invention may not be sufficiently exhibited in many cases. However, the content may be other than the above value if necessary. In this case, it is natural that the category described in the stepwise manner includes an inclined configuration.

Although the content of the conductive agent in the inner surface layer is not particularly limited, it is preferably 10 to 30% by weight, and if it is less than 10% by weight, the desired conductivity cannot be obtained. In many cases, it is not preferable because the target characteristics are impaired, but depending on the application, a value other than this value can be used. Also, the conductive agent content of the surface layer is gradually reduced from the inner surface, may not be included at all, or may contain a required amount less than the inner surface,
The content is not particularly limited, but is preferably 2 to 10
About% by weight can be exemplified. At this time, if necessary, one or more intermediate layers may be provided between the surface layer and the inner surface layer, and the conductive agent content of the intermediate layer may be an intermediate amount between the surface layer and the inner surface layer. Good. In this case, when two or more intermediate layers are provided, the amount of the conductive agent is gradually reduced from the layer disposed on the inner surface side to the layer disposed on the surface layer side so as to decrease from large to small. It is desirable to make it.

The inner surface layer and the surface layer may be different resins, and the intermediate layer provided as necessary may be a resin layer having a mixed structure of both resins. In this case, it is preferable that the mixed composition be reduced stepwise so that the content of the resin constituting the inner surface becomes smaller from the inner surface layer to the surface layer, but the present invention is not particularly limited to this.

Further, in order to protect the conductive multilayer tube, a protective layer may be further provided on the surface layer to form an outermost layer, and the outermost layer is mainly composed of an organic polymer material containing no conductive agent. However, if necessary, an appropriate filler may be contained, and this is not particularly limited.

The conductive multilayer tube having the above structure is coated on, for example, a roll having a conductive elastic layer. When the conductive multilayer tube is used as, for example, a charging roll by a contact charging method, the photoreceptor is charged by the charging roll. Also,
Since the tube has little variation in resistance in each layer and a change in resistance due to the environment, and furthermore, the withstand voltage is improved, the charging roll using such a tube can uniformly charge the photoconductor and the like. Thus, a better image can be obtained. In addition, such a charging roll can also prevent bleed-out from the elastic layer in the roll, and provide good interlayer adhesion. The reason why bleed-out can be prevented is that the conventional charging roll has a single layer of coating tube, so the conductive agent is evenly distributed, so the softener in the elastic body passes through the conductive agent in the tube to the outer surface. Although the bleed-out has occurred, the tube of the present invention has a multilayer structure, and the content of the conductive agent is smaller in the surface layer. by. Therefore, to further prevent bleed-out,
It is more desirable to provide a protective layer containing no conductive agent on the surface layer.

Examples of the organic polymer material constituting the conductive multilayer tube of the present invention include various thermoplastic elastomers, polycarbonate, polyester, polyarylate, and the like.
Thermoplastic resins such as polyphenylene sulfite, polyamide, polysulfone, polyparabanic acid, fluororesin, polyvinyl chloride, polystyrene, thermoplastic polyimide resin and polyurethane (polyester, polyether), and copolymers derived therefrom , A mixture and the like can also be exemplified, but other than this, it is sufficient to select and use an appropriate one such as a thermosetting resin, and it is not particularly limited,
Rather, those that can be extruded are often used.

The conductive agent according to the present invention is preferably a conductive carbon black, for example, carbon black such as acetylene black and Ketjen black (conductive furnace black), but is not limited thereto. Powders, metal oxides such as tin oxide, indium oxide and the like and other conductive materials may be used, and there is no particular limitation. If necessary, stabilizers, lubricants, pigments, dyes, UV inhibitors, fillers, and other various resins may be added, and there is no particular limitation.

In order to form the conductive multilayer tube of the present invention, a method in which an annular die is attached to a plurality of extruders and the film is formed by coextrusion becomes a seamless tube.
Other than this, a plate-shaped coextrusion method or a film having a plurality of conductive agent contents different from each other was formed and laminated by an appropriate method such as a pressure bonding method or a dry laminating method so that the conductive agent content was changed stepwise. It may be formed into a tube using a multilayer film, and there is no particular limitation. The multilayer tube may be formed by centrifugal molding or other methods.

The stretching and / or heat treatment of the conductive multilayer tubular film of the present invention is not particularly limited and may be carried out as needed, and any suitable method such as a tubular method, a tenter method and the like can be used. However, the present invention is not limited to this. Further, the film may be made heat-shrinkable by stretching to be used as a shrink tube. At this time, the heat shrinkage rate is not particularly limited and may be set to an appropriate value as needed, and is usually 0 to 10% in the axial direction and 10 to 10 in the circumferential direction.
A value of about 80% can be exemplified.

When a protective layer is required, the thickness of the conductive multilayer tube of the present invention can be, for example, about 5 to 50 μm, more preferably about 10 to 30 μm, and when it is 50 μm or more, the resistance of the protective layer becomes large. This is often not preferred, but there is no particular limitation on such values. The surface layer is 1
The thickness is preferably from 0 to 200 μm and the thickness of the inner surface layer is from 30 to 200 μm, but there is no particular limitation, and the thickness may be appropriately determined depending on the application.

The conductive multilayer tube of the present invention is preferably used for a roll-coated tube, for example, a coated tube such as an electrophotographic copying machine for primary charging, transfer, and neutralization rolls. However, the present invention is not limited to this and can be widely used for other uses, and can be expected to expand in future.
In the case of a roll-coated tube, the roll and the tube may be coated via an appropriate adhesive substance, or may be directly coated without using an adhesive substance (may be used if necessary). In this case, it is often preferable to use a material having heat shrinkability as a shrink tube.

Hereinafter, the present invention will be described with reference to examples.

[0020]

【Example】

Example 1 Three co-extrusion dies were attached to three extruders, and a urethane-based resin was used as a main component, and the Ketjen black content in each layer was 15% by weight, 10% by weight, and 5% by weight on the inner surface. , And the compositions were added to each extruder in such a manner that the compositions were gradually reduced from large to small along the surface layer. Each composition is extruded in a molten state by a screw in an extruder heated to a cylinder temperature of 180 ° C. and a die temperature of 195 ° C., and then cooled by an inflation method to form a film. The conductivity of the inner surface layer is maximum. A conductive multilayer tube having a configuration in which the conductivity of the surface layer was minimized was obtained. Then, when it was stretched in the circumferential direction twice at 95 ° C. to form a shrink tube,
The total thickness of such a tube body is 150 μm (20 μm, 70 μm, 60 μm from the surface layer), the inner diameter is 15 mm, and the volume electric resistance is 10 ⁶ Ω · cm, 10 ⁵ Ω · cm, 1
0 was ^{4 Ω} · cm. This conductive multilayer tube was cut at a length of 25 cm in a direction perpendicular to the stretching direction to produce a tube for covering a conductive roll of a copying machine. On this occasion,
The conductive roll had an outer diameter of 12 mm having a conductive rubber layer of about 3 mm on an iron core. When a conductive roll shrink-coated with this tube is used as a charging roll and charged by a contact charging method, the roll has a small variation in resistance value, a small change in resistance due to the environment, and a high withstand voltage. Bleeding out of the softening agent of the soft roll was also prevented. Furthermore, the printability was excellent, and a clear image could be obtained even when continuous copying was performed, and the effect was exceptional.

Example 2 Among the four extruders, one of the co-extruders in which an annular co-extrusion die was attached was a composition mainly composed of a polyvinyl chloride resin serving as an outermost layer as a protective layer. A conductive multilayer shrink tube provided with an outermost layer (protective layer) was obtained in the same manner as in Example 1 except for supplying. From the outermost layer, the thickness of the tube thus obtained was 20 μm, 20 μm, 60 μm and 60 μm.
μ, total thickness 160 μ, volume electric resistance value is 10 ⁸ Ω · cm, 10 ⁶ Ω · cm, 10 ⁵ Ω · cm from the outermost layer,
It was 10 ⁴ Ω · cm. After the conductive multilayer shrink tube was cut in the same manner as in Example 1, the contact charging type copying machine, in which the conductive roll covered with the tube was used as the charging roll in the same manner as in Example 1, was charged with the charging roll. Even when electrified, the variation in the resistance value of the charging roll, the change in resistance value due to the environment is small, the withstand voltage is improved, and the bleed out of the softener in the conductive rubber layer in the conductive roll can be prevented, and the photoconductor can be used. Since it was uniformly charged, a clear copy could be obtained.

Example 3 (1) The composition of the inner surface layer is 85% by weight of a polyurethane resin.
And a Ketjen Black 15% by weight. (2) The composition of the intermediate layer is 63% by weight of a polyurethane resin,
A composition comprising 27% by weight of a composition mainly composed of a polyvinyl chloride resin and 10% by weight of Ketjen black. (3) Composition 6 whose outer surface layer is composed of 28.5% by weight of a polyurethane resin and a polyvinyl chloride resin as a main component
A blended composition comprising 6.5% by weight and 5% by weight Ketjen black. (4) A composition in which the composition of the outermost layer (protective layer) contains 100% by weight of a composition mainly composed of a polyvinyl chloride resin. Each of the blended compositions (1), (2), (3) and (4) was formed into a conductive multilayer tube in the same manner as in Example 1. This conductive multilayer tube was subjected to 25c in the same manner as in Example 1.
m to obtain a conductive roll-coated shrink tube. The volume electric resistance value of each layer is 10 ⁸ Ω · cm, 10 ⁶ Ω · cm, 10 ⁵ Ω · cm, 1 from the outermost layer (protective layer).
0 was ^{4 Ω} · cm. The contact charging type copier equipped with a conductive roll covered with the tube as a charging roll has a small variation in the resistance value of the charging roll even if the charging roll is charged, a small change in the resistance value due to the environment, and an improved withstand voltage. In addition, excellent bleed-out of the softener in the conductive roll can be prevented, and the photoreceptor is uniformly charged, so that clear copying is possible, and a clear image can be obtained even when continuous copying is performed. Met. At this time, the heat shrinkage of the shrink tube in each of the examples was 5% in the axial direction and 50% in the circumferential direction in the atmosphere of 120 ° C. for 3 minutes.
%, That of Example 2 was also 5% and 50%, and that of Example 3 was also 5% and 50%.

[0024]

The conductive multilayer tube according to the present invention is expected to be able to reduce the variation of the resistance value in each layer and the change of the electrical resistance due to the environment, and to improve the withstand voltage. Furthermore, since it is not a single-layer structure as in the prior art, but has a multilayer structure and a structure in which the content of the conductive agent is smaller as it becomes the surface layer, for example, when it is applied to a roll having a conductive elastic material layer, it is softened from the roll. It also has the effect of reducing bleed-out of the agent.
The conductive multilayer tube of the present invention can be used for any purpose other than the roll coating of a copying machine in the future, and it can be expected to expand the use in a wide range of fields.

Claims (3)

(57) [Claims] 1. The method according to claim 1, wherein the content of the conductive agent in each layer containing an organic polymer material as a main component is gradually reduced from large to small from the inner surface layer to the surface layer. A multilayer tube having at least two layers, the inner surface layer having the highest conductivity and the surface layer (containing 2 to 10% by weight of a conductive agent).
(B) a conductive multilayer tube having a configuration having a minimum conductivity. 2. Each layer mainly composed of an organic polymer material
From the inner surface layer to the surface layer,
Within the composition that is gradually reduced so that it becomes smaller
2. A structure comprising three layers: a surface layer, an intermediate layer, and a surface layer.
2. The conductive multilayer tube according to item 1. 3. An organic material containing no conductive agent on the surface layer.
No protective layer (resistive layer) mainly composed of polymer material
The conductive multilayer tube according to claim 1.