JPH07295330A - Conductive elastic material - Google Patents

Abstract

PURPOSE:To obtain safety such as enough heat resistance and weather resistance and to facilitate miniturization of devices such as an electrophotographic device and an electrostatic recording device by specifying the remaining rate of fracture elongation of a conductive elastic material after heating according to JISK6301 under specified heating conditions. CONSTITUTION:This conductive elastic material is used as the main material of a conductive member such as an electrifying member, transferring member, developing member and cleaning member used for an electrophotographic device, electrostatic recording device, and the like. The remaining rate of fracture elongation of this material after heating according to JISK6301 under heating conditions of 170 deg.C for 50 hours is specified to >=50%, preferably to >=60%, and more preferably to >=70%. The main material of the conductive elastic material is not limited, and fluororubber, silicone rubber, ethylene-propylene rubber EPM, ethylene-propylene-diene ternary copolymer rubber EPDM, acryl rubber, epichlorohydrin rubber can be used. These materials may be used singly or in the mixture of two or more kinds.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive material which is a main material of a conductive member such as a charging member, a transfer member, a developing member and a cleaning member used in electrophotographic devices such as copying machines and printers and electrostatic recording devices. Elastic material.

[0002]

2. Description of the Related Art Conventionally, a large number of conductive elastic materials made of rubber or resin have been used in electrophotographic devices such as copying machines and printers, and electrostatic recording devices. However, the heat resistance of the electrophotographic processes so far, particularly, the processes such as charging, development, transfer, cleaning, etc., has been hardly required. On the other hand, it is known that heat-resistant silicone rubber is used as the main material of the member in the fixing process, which is the only exposure process under a heating condition in the series of electrophotographic processes. There was no

However, with the recent simplification and miniaturization of electrophotographic devices and electrostatic recording devices, it has become impossible to say that the characteristics of conventional conductive members are sufficient.
That is, in order to simplify and miniaturize these devices, there are increasing cases in which the conductive member is arranged near the heat source or the conductive member itself is heated.

For example, in the electrophotographic apparatus as shown in FIG. 1, the developing roller 7 is in contact with the photosensitive drum 6 between the toner applying roller 9 for supplying the toner and the photosensitive drum 6 holding the electrostatic latent image. And the developing rollers 7,
By rotating the photosensitive drum 6 and the toner application roller 9 in the direction of the arrow in the figure, unnecessary toner 10 is supplied from the toner application roller 9 and the toner formed into a uniform thin film by the layering blade 8 is developed. The latent image on the photosensitive drum 6 is adhered from the roller 7 to be visualized. A cleaning unit 4 removes toner remaining on the surface of the photosensitive drum 6 by the cleaning blade 5 after transfer.

The toner adhering to the photosensitive drum 6 is transferred onto the transfer roller 1 and further transferred onto the transfer paper 3 on the fixing roller 2.
The fixing roller 2 is heated to, for example, 180 ° C. in order to fix the toner 10 thereon. In the process illustrated in FIG. 1, since the transfer roller 1 and the fixing roller 2 are close to each other, it is easy to downsize the apparatus, but the transfer roller 1 is required to have heat resistance.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and when an electrophotographic apparatus or an electrostatic recording apparatus is downsized, these charging members, transfer members,
An object of the present invention is to provide a conductive elastic material that allows a conductive member such as a developing member and a cleaning member to have sufficient safety (heat resistance, weather resistance, etc.).

[0007]

The electrically conductive elastic material of the present invention is brought into contact with a member to be charged and a voltage is applied between the member and the member to be charged to charge the member to a predetermined polarity. Alternatively, in the conductive elastic material which is the main material of the conductive member for static elimination, JISK63 is used under the heating condition of 170 ° C. for 50 hours.
The residual rate of elongation at break after heating at 01 is 50% or more.

Further, the conductive elastic material of the present invention is characterized by having a volume specific resistance value of 10 ³ to 10 ¹⁰ Ω · cm.

Further, the conductive elastic material of the present invention is mainly composed of fluororubber, silicone rubber, EPM, EPD.
It is characterized in that M, acrylic rubber, and epichlorohydrin rubber are used alone or in a mixture of two or more kinds.

[0010]

The conductive elastic material preferably used for the conductive member is required to have conductivity according to various characteristics and to be highly safe. Therefore, it cannot be said that the safety, for example, the heat resistance and the weather resistance is necessarily sufficient because a special blending is required for improving the function of the. However, according to the conductive elastic material of the present invention, while utilizing the characteristics of various conventional members, and since it is possible to improve the heat resistance, there is no problem even if it is arranged close to a heat source, and As a result, it is possible to easily reduce the size of the device.

[0011]

The present invention will be described in more detail below. In the present invention, the heat resistance of the conductive member is evaluated by calculating the residual rate A _R (E _B ) of the breaking elongation after the heating test by the following formula according to JIS K6301 (1975) which is a physical test method for vulcanized rubber. To do.

[0012]

[Equation 1]

In this equation, A _R (E _B ) is the residual rate (%) after heating with respect to the breaking elongation of the sample before heating, S _{11 to} S
₁₄ is a measured value in which the breaking elongation (%) of the sample piece before heating is arranged in the measurement order, and S _{21 to} S ₂₄ are measured values in which the breaking elongation (%) of the sample piece after heating is arranged in the measuring order. ing.

In the present invention, this heating test is performed in air at 170
Under the condition of 50 ° C. for 50 hours, the residual rate A _R (E _B ) is 50% or more, preferably 60% or more, more preferably 70% or more. Here, the fact that the residual rate decreases after heating indicates that the conductive member is deteriorated as a physical property, and it can be said that the higher the residual rate, the more conductive elastic material the heat resistance is. If the residual rate is less than 50%, the physical properties required for the conductive elastic material cannot be obtained.

The main material of the conductive elastic material of the present invention is:
Although not particularly limited, rubber is suitable as a flexible component used in the shape of a roller or a belt in an electrophotographic apparatus or an electrostatic recording apparatus. However, since the physical properties of the rubber composition depend on the compounding, the type of rubber cannot be limited, but fluororubber, silicone rubber, EPM (ethylene-propylene rubber), EPDM
(Ethylene-propylene-diene terpolymer rubber),
Examples thereof include acrylic rubber and epichlorohydrin rubber. These may be used alone or in combination of two or more. Note that materials other than these materials are not preferable in terms of the residual rate after the heating test.

The conductivity-imparting agent to be blended with the conductive elastic material of the present invention is not particularly limited, but carbon black is usually preferably used, whereby the volume resistivity of this member is from 10 ³ to 10 ^{3. 10} Ω · cm, especially,
It is preferably 10 ⁴ to 10 ⁹ Ω · cm. In addition,
If the volume resistivity is less than 10 ³ Ω · cm, it is not preferable in terms of charge leakage, and the volume resistivity is 10 ⁹ Ω · cm.
If it exceeds, it is not preferable in terms of electrical conductivity.

The amount of the conductivity-imparting agent blended varies greatly depending on the type of carbon black, but normally rubber 100 is used.
The amount is preferably 1 to 100 parts by weight, and particularly preferably 1 to 70 parts by weight. In this case, generally, when carbon black having a small particle size is used, a small compounding amount is sufficient, and conversely, when carbon black having a large particle size is used, the compounding amount is large. In addition, the compounding amount of the conductivity-imparting agent is 10
If it exceeds 0 parts by weight, the hardness is excessively increased, which is not preferable.

For the purpose of adjusting the resistance value of the elastic layer,
A small amount of an ion conductive substance such as sodium perchlorate or tetraethylammonium chloride or a surfactant such as dimethylpolysiloxane or polyoxyethylene lauryl ether may be blended with the carbon black. The compounding amount of these is 0.
It can be 1 to 10 parts by weight. It should be noted that if the blending amount of these exceeds 10 parts by weight, the resistance value becomes too low, which is not preferable.

Further, a cross-linking agent and a vulcanizing agent may be added in order to cross-link with the rubber to form a rubber-like substance. In this case, a cross-linking aid, a cross-linking accelerator, a cross-linking retarder or the like can be used in both organic peroxide cross-linking and sulfur cross-linking. In addition to the above, peptizers, foaming agents, plasticizers, softening agents, tackifiers, anti-tacking agents, dispersants, release agents, extenders, colorants, etc. which are generally used as compounding agents for rubber. Can be added.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(Application Example Using the Conductive Elastic Material of the Present Invention) FIG. 1 is a schematic view of an electrophotographic apparatus showing an embodiment of a conductive member using the conductive elastic material of the present invention. The toner attached to the photosensitive drum 6 is transferred onto the transfer roller 1, and the fixing roller 2 is heated to 180 ° C. in order to fix the toner 10 onto the transfer paper 3 on the fixing roller 2. In the process of FIG. 1, since the transfer roller 1 and the fixing roller 2 are close to each other, it is easy to downsize the device, but
Since the heat resistance of the transfer roller 1 is required, the transfer roller 1 is formed by using the conductive elastic material of the present invention as a main material. Although it is used as a transfer roller here as an example of application, it can be suitably used as a flexible component used in the shape of a roller or a belt in a charging member, a transfer member, a developing member, a cleaning member, and the like. .

[0022]

Example 1 EPDM (Nippon Synthetic Rubber, EP33) 1
HAF carbon 60 parts by weight, zinc oxide 5 parts by weight, stearic acid 1 part by weight, vulcanization accelerator mercaptobenzothiazole (MBT) 0.5 parts by weight and tetramethylthiuram monosulfide (TMTM) with respect to 00 parts by weight.
1.5 parts by weight and 1.5 parts by weight of sulfur were mixed in a roll mill and molded in a mold preheated to 150 ° C. for 30 minutes at a pressure of 100 kg / cm ² to obtain a 2 mm thick sheet.
The volume resistivity at this time was 6 × 10 ⁵ Ω · cm.
In addition, this sheet was heated at 170 ° C for 50 hours before and after heating.
The residual elongation at break was measured according to IS K6301 and found to be 70%.

[0023]

Example 2 The obtained sheet was evaluated in the same manner as in Example 1 except that the rubber material was changed to silicone rubber.

[Table 1]

[0024]

[Example 3] Table 1 shows an evaluation of the obtained sheet in the same manner as in Example 1 except that the rubber material was changed to fluororubber.

[0025]

Example 4 The obtained sheet was evaluated in the same manner as in Example 1 except that the rubber material was changed to acrylic rubber.

[0026]

Example 5 Table 1 shows an evaluation of the obtained sheet in the same manner as in Example 1 except that the rubber material was changed to epichlorohydrin rubber.

[0027]

Comparative Example 1 The obtained sheet was evaluated in the same manner as in Example 1 except that the rubber material was changed to chloroprene rubber (CR). As a result of evaluation, the residual rate of elongation at break was 45% and the heat resistance was insufficient.

[0028]

[Comparative Example 2] Table 1 shows an evaluation of the obtained sheet in the same manner as in Example 1 except that the material of the rubber was changed to nitrile rubber (NBR). As a result of evaluation, the residual rate of elongation at break was 45% and the heat resistance was insufficient.

[0029]

Comparative Example 3 The procedure of Example 1 was repeated except that the rubber material was changed to styrene-butadiene rubber (SBR).
Table 1 shows the evaluation of the obtained sheet. As a result of evaluation, the residual rate of elongation at break was 40% and the heat resistance was insufficient.

[0030]

[Comparative Example 4] Table 1 shows an evaluation of the obtained sheet in the same manner as in Example 1 except that the rubber material was changed to natural rubber (NR). As a result of evaluation, the residual rate of elongation at break was 40% and the heat resistance was insufficient.

[0031]

As described above, according to the conductive elastic material of the present invention, while utilizing the characteristics of various conventional members,
In addition, since the heat resistance can be improved, there is no problem even if the heat source is arranged close to the heat source, and this brings about an excellent effect that the size of the device can be easily reduced.

[Brief description of drawings]

FIG. 1 is a schematic view of an electrophotographic apparatus showing an embodiment of a conductive member using the conductive elastic material of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Transfer roller 2 ... Fixing roller 3 ... Transfer paper 4 ... Cleaning section 5 ... Cleaning blade 6 ... Photosensitive drum (latent image holding member) 7 ... Developing roller 8 ... Layering blade 9 ... Toner applying roller 10 ... Toner

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[Procedure amendment]

[Submission date] May 12, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

[0023]

Example 2 The obtained sheet was evaluated in the same manner as in Example 1 except that the rubber material was changed to silicone rubber.

[Table 1]

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Claims (3)

[Claims] 1. A conductive elastic material, which is a main material of a conductive member used by applying a voltage to a photosensitive member in contact with the photosensitive member, is subjected to JIS K6 under heating conditions of 170 ° C. and 50 hours.
A conductive elastic material, wherein the residual rate of elongation at break after heating at 301 is 50% or more. 2. The conductive elastic material according to claim 1, wherein the conductive elastic material has a volume resistivity value of 10 ³ to 10 ¹⁰ Ω · cm. 3. The main material of the conductive elastic material is fluororubber, silicone rubber, EPM, EPDM, acrylic rubber, epichlorohydrin rubber, or a mixture of two or more thereof is used. Or the conductive elastic material according to 2.