JPH0726069A - Molded rubber structure for charge elimination and its use - Google Patents

Abstract

PURPOSE:To provide a molded rubber structure which is disposed within an electrophotographic copier and can effectively discharge static electricity. CONSTITUTION:The structure is prepared by molding a composition prepared by mixing a rubber with carbon fibers and conductive whiskers. The most desirable embodiment of this structure is a charge elimination rubber roll composed of a metallic core and a rubber layer surrounding this core. Other effective embodiments are a charge elimination blade and a charge elimination sheet. This structure is desirably in a state in which part of the carbon fibers or conductive whiskers are exposed to its surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rubber molding structure that effectively removes static electricity, and more specifically, it is mounted on an electrophotographic copying machine, various OA equipment, etc. Various molded structures for effectively removing various obstacles.

[0002]

2. Description of the Related Art Rolls for supplying or conveying paper or film are used in OA equipment such as electrophotographic copying machines and printers of various terminals. This roll is usually made of rubber such as NBR, but in the above-mentioned equipment, static electricity is generated by friction of paper or the like during operation, so that supply or conveyance of paper or film may not be smoothly performed. . In addition, the phenomenon that it is difficult to align the papers after finishing printing with a copying machine is a trouble caused by static electricity.

Further, when a large amount of static electricity is generated, sparks are generated, and in a printing factory or the like which uses a large amount of highly flammable ink solvent, it is feared that the spark may cause a fire. Therefore, the development of a static elimination roll having excellent static elimination effect is urgently needed.

As a countermeasure against such a trouble caused by static electricity, conductive powder such as carbon black or metal powder is added to the rubber layer of the transport roll to impart conductivity to the roll, or the rubber layer is prevented from static electricity. Although methods such as adding agents have been tried, these methods can suppress the generation of static electricity to some extent, but the static electricity removal effect of static electricity once generated is not sufficient, and the influence of static electricity is still eliminated. , It is difficult to smoothly convey, and when the conductivity imparting agent or the antistatic agent as described above is added to the rubber layer of the conveying roll, extremely accurate physical properties such as elasticity are required. The properties of the transport roll that is used may change subtly, which may adversely affect the transport performance.
There is a demand for rolls that have both improved transport performance and static elimination performance.

The influence of static electricity on the operation of equipment is
Not only the rubber rolls described above, but also blades, sheets (goodwill), keyboards, and even discharge belts used in various OA devices can occur in the same manner, and countermeasures against static elimination are awaited.

In view of the above technical requirements, the applicant of the present invention inserts a static elimination ring made of rubber containing carbon fiber or a porous body between the conveying rolls having a rubber layer on the outer circumference of the shaft. Developed a roll for transportation, and applied for 1
The application has been made as No. -23078. Even after that, while continuing the research in search of a rubber molded body having a further excellent static elimination effect, it was found that such a purpose can be more effectively achieved by molding a compounded mixture of specific conductive substances. And completed the present invention.

[0007]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a molded structure having a remarkably excellent static elimination effect. Above all, the purpose is to eliminate static electricity from rubber rolls, elastomer blades, elastomer sheets, mats, tapes, hoses and the like. To provide a molded structure.

[0008]

The present invention has been proposed in order to achieve the above-mentioned object, and it is an important feature that the carbon fiber and the conductive whiskers are compounded in the rubber compounding composition. is there. That is, according to the present invention, there is provided a static elimination rubber molding structure molded from a composition in which carbon fibers and conductive whiskers are mixed in rubber. As a mode of the rubber molding structure for static elimination in the present invention, a rubber roll for static elimination having a core metal and a rubber layer on the outer peripheral surface of the core metal is first mentioned. A second aspect of the rubber molding structure for static elimination is a static elimination blade. further,
A third embodiment of the static elimination rubber molded structure is a static elimination sheet. Other embodiments include the above-mentioned molded structure for the purpose of eliminating static electricity, such as the mat, tape, and hose. Since these molded structures are present with a part of the carbon fibers or the conductive whiskers, especially the tip end portion protruding like whiskers on the surface thereof, the static elimination effect is further enhanced.

[0009]

As previously proposed by the applicant, in the case where only the carbon fiber is blended in the rubber composition, the static electricity generated from the rubber layer is discharged into the air through the carbon fiber in the static elimination ring to eliminate static electricity. In the present invention, the combined use of carbon fibers and conductive whiskers, by the conductive whiskers to contact the carbon fibers present in the rubber, the discharge into the air is efficient. Is done
As a result, a molded product such as a transport roll, an elastomer blade or an elastomer sheet molded from such a composition has a significantly excellent static elimination effect.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The most technical feature of the present invention is that carbon fibers and conductive whiskers are used in combination in the above-mentioned molding elastomer composition and molded into respective molded bodies. It is in.

Any known carbon fiber such as PAN-based carbon fiber and pitch-based carbon fiber can be used as the carbon fiber, and the thickness and length of the fiber are not particularly limited. It can be arbitrarily selected and used according to the shape and size of the molded body. As a preferred carbon fiber for use in the present invention, Soldion (trade name) manufactured by Toray Industries, Inc. may be mentioned.

The blending amount of the carbon fiber is 0.5 to 30% by weight, preferably 1 to 20% by weight, based on the whole elastomer composition. If the blending ratio of the carbon fibers is less than the above range, the static elimination effect is not sufficient, and if it is more than the above range, physical properties such as abrasion as a transport roll or an elastomer blade tend to be slightly reduced. Not only is it uneconomical in terms of price.

When the conductive whiskers are used in combination with the carbon fibers, static electricity is effectively transmitted at the contact portions between the whiskers and discharge into the air is effectively performed. Whiskers (commonly known as cat whiskers) are the names given to fine needle-like crystals, and are "single crystals with a cross-sectional area of 8 × 10 ^-5 in ² or less and a length of 10 times or more the average diameter of the cross-section." Is defined as However, in reality, what is not a single crystal is often called a whisker.
The conductive whiskers in the present invention are those completed by imparting conductivity to the potassium titanate whiskers using a strictly controlled new ceramics technique.

In the use of the present invention, preferred is Dentol BK-300 (trade name) manufactured by Otsuka Chemical Co., Ltd. The characteristics of this conductive whisker are that it is chemically and physically extremely stable, has unique conductivity, and inherits all of the excellent basic properties (fine fiber shape, reinforcement, etc.) of potassium titanate whiskers. is there.

The content of the conductive whiskers is 0.5 to 30% by weight, preferably 1 to 20% by weight, based on the whole elastomer composition. When the compounding ratio of the conductive whiskers is less than the above range, the static elimination effect is small, so that it is used for conveying paper such as OA equipment, and when it is more than the above range, physical properties such as abrasion are deteriorated and the cost is reduced. It will be up.

The mixing ratio of the carbon fibers and the conductive whiskers is not particularly limited, but carbon fiber: conductive whiskers = 1: 3 to 1: 2 in order to obtain an effective static elimination effect. It is preferable. The fiber diameter of the conductive whiskers used in the present invention is preferably as thin as possible for more effective discharge in the air, and the diameter is usually 0.3 to 1.4 μm, particularly 0.5 to 1.0 μm.
It is preferably m, and the length thereof is preferably about 5 to 30 μm. Although carbon fibers having a small fiber diameter are also preferable, any commercially available carbon fibers can be used, and the length thereof is usually about 6 to 7 mm in the case of the Soldion.

The static elimination rubber molded structure of the present invention may exist on the surface of the molded product in a state where a part of the carbon fiber or the conductive whiskers is exposed, and particularly in a state where the tip portion protrudes like a whiskers. preferable. A part of the carbon fiber or conductive whiskers, especially the tip part, is exposed, so the static electricity generated inside the molded body is efficiently discharged from the tip part into the air, resulting in a molding with excellent static elimination effect. Become a body. In order to expose the tips of the carbon fibers and the conductive whiskers, for example, the surface of the molded body is simply polished with a grindstone, and the whisker tips are exposed on the surface, whereby the target molded structure is obtained. Can be easily obtained.

The material of the elastomer constituting the static elimination rubber molding structure of the present invention includes chloroprene rubber and NB.
R, EPDM, synthetic rubber such as urethane rubber, especially hardness
A material having a (Hs) of 50 ° to 80 ° (JIS A) is preferably used, and in addition to this, a porous body such as natural rubber, sponge, porous synthetic resin having elasticity, and sponge is used without any limitation. can do.

As the compounding agent other than the rubber, the carbon fiber and the conductive whiskers, a compounding agent for rubber known per se, such as conductive carbon black, is used according to a conventional method.

In the present invention, the rubber compound having the above composition is kneaded and vulcanized by a conventional method to obtain a molded product such as a static eliminating roll, an elastomer blade, an elastomer sheet, a mat, a hose or a tape. The above-mentioned molding structure such as the static elimination roll is kneaded in a kneader according to the specified composition, then the open roll is added with a vulcanizing agent and a vulcanization aid, the sheet is taken out, and then the sheet is subjected to an electrothermal press molding method, for example, at 160 ° C It can be molded by a method of molding under conditions of × 15 minutes × 150 kg / cm ² or a steam vulcanization molding method.

[0021]

According to the present invention, the carbon fibers and the conductive whiskers mixed in the composition forming the rubber molding structure come into contact with each other at many points inside the molded body, and the carbon fibers or the conductive whiskers Since at least a part of the molded body is exposed on the surface of the molded body, the static electricity generated inside the molded body is entangled at the contact point and discharged from the exposed portion of the molded body surface into the air, resulting in an efficient static elimination effect. A rubber molding structure can be provided which is achieved.

[0022]

EXAMPLES The present invention will be described below with reference to examples.
This is to explain a preferred embodiment of the present invention, and the present invention is not limited thereby. <Example> Blend composition NBR ("Nipol 402" manufactured by Nippon Zeon Co., Ltd.) 100 parts by weight Hardness 80 ° (JIS A) Ketjen Black EC 20 parts by weight Conductive whiskers ("Dentor BK-300") 20 parts by weight DOP 10 Parts by weight carbon fiber (“Soldion”) 10 parts by weight sulfur 5 parts by weight

The composition having the above composition was kneaded and vulcanized by a conventional method to form the carrying roll shown in FIG. Figure 1
In the above, 1 indicates a core metal, and 2 indicates a roll. Roll outer diameter φ25.5 mm Roll length 50 mm Core metal outer diameter φ15 mm The static elimination rate [%] was measured by the following method. Static electricity is generated in the PET film which is stretched between the driving pulley and the driven pulley and rotates, and first, the static electricity on the film surface is measured with a potential measuring device (manufactured by Kasuga Denki Co., Ltd.), and this is measured before static elimination [KV]. And Then, a roll is brought into contact with the surface of the PET film, and then the potential is measured again by a potential measuring device, which is taken as [KV] after static elimination. From this measured value,
The following formula The static elimination rate was measured by. The charge removal rate of this roll is shown in Table 1.

<Comparative Example 1> A roll was similarly molded with a composition containing conductive carbon black instead of the carbon fiber and the conductive whisker in the composition of the example. The results of measuring the static elimination rate are shown in Table 1.

<Comparative Example 2> A roll was formed in the same manner as in Example except that the conductive whiskers were omitted. The results of measuring the static elimination rate are shown in Table 1.

[0026]

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a rubber roll that is a preferred embodiment of a rubber molding structure of the present invention.

[Explanation of symbols]

 1 core 2 rolls

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G03G 15/00 510 2107-2H 21/10 21/06 H05F 1/00 J 9470-5G // B29K 21:00 105: 12

Claims (5)

[Claims] 1. A rubber molding structure for static elimination, which is molded from a composition obtained by mixing carbon fiber and conductive whiskers in rubber. 2. The molded structure according to claim 1, wherein the molded structure is a static elimination rubber roll having a cored bar and a rubber layer on the outer peripheral surface of the cored bar. 3. The molded structure according to claim 1, wherein the molded structure is a static elimination blade. 4. The molded structure according to claim 1, wherein the molded structure is a static elimination sheet. 5. The molding structure according to claim 1, wherein carbon fibers or conductive whiskers are present on the surface of the molding structure in a partially exposed state.