JP2000256557A - Semiconductive roll - Google Patents

Abstract

(A) Abstract: (A) Ethylene propylene rubber and / or
Or ethylene / propylene / diene rubber
5 to 98 parts by weight (B) The following average composition formula (1) R _n SiO _{(4-n) / 2} (1) (where R is a substituted or unsubstituted monovalent hydrocarbon group,
n is a positive number from 1.95 to 2.05. ) Organopolysiloxane 2
95 parts by weight (C) 5 to 20 parts by weight based on 100 parts by weight of the total of the spherical silicone elastomer particles (A) and (B) having an average particle diameter of 0.1 to 100 μm.
0 part by weight, (D) A semiconductive roll, wherein a semiconductive rubber cured layer of a conductive rubber composition containing a conductive material is formed on a cored bar. The semiconducting roll of the present invention is stable in the electric resistivity in the semiconductive region without being influenced by the molding conditions, has very little variation, and is excellent in moldability, vulcanization characteristics and rubber elasticity. It is a thing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a semiconductive region (10
^The present invention relates to a semiconductive roll exhibiting stable electric resistance at ³ to 10 ¹⁰ Ω · cm.

[0002]

2. Description of the Related Art
Various conductive rubbers in which a conductive material is blended with a rubber-like substance exhibiting electrical insulation properties are known. For example, carbon black or the like is blended as a conductive material, and the electrical resistance is 10 ^-1 to 10.
Conductive rubber in the range of ² Ω · cm has been applied in a wide range of fields. On the other hand, ethylene-propylene-diene rubber (hereinafter referred to as EPDM) and silicone rubber, which are one of the electrically insulating rubber-like substances, have excellent heat resistance, cold resistance, and weather resistance, and are widely used as the electrically insulating rubber. However, by adding a conductive material like other rubber-like substances, it has been put into practical use as a conductive rubber. Further, Japanese Unexamined Patent Publication No.
Japanese Patent No. 302232 proposes to add a silicone rubber powder to an organic rubber other than the silicone rubber, but it is necessary to use both a conductivity imparting agent by electron conduction and a conductivity imparting agent by ionic conduction. It is not versatile and the stability of the resistance of the semiconductive region is insufficient.

In this case, as a conductive material to be added to the conductive EPDM or the conductive silicone rubber, for example, various metal powders such as carbon black, graphite, silver, nickel and copper, various non-conductive powders, and short fiber surfaces are used. Is treated with a metal such as silver, mixed with carbon fiber, metal fiber, etc., without deteriorating the specific characteristics of rubber, and the electrical resistivity of silicone rubber is determined by the type and filling amount of the conductive material. It is frequently used because it can be reduced to about 10 ¹⁰ to 10 ⁻³ Ω · cm.

However, when conductive carbon black such as Ketjen black and acetylene black is blended with synthetic rubber, the variation in electrical resistivity becomes extremely large in a semiconductive region of 10 ³ Ω · cm to 10 ¹⁰ Ω · cm. Was difficult to stabilize. This is considered to be due to the fact that the dispersion of carbon significantly changes depending on molding conditions.

[0005] Recently, however, parts of OA equipment, in particular, a charging roll, a transfer roll, and the like in a dry copying machine have been developed.
Developing roll, paper feed roll, fixing roll, pressure roll,
The need for semiconductive rolls has increased as rubber rolls such as static elimination rolls, cleaning rolls, and oil application rolls.
For this reason, there is a demand for a semiconductive roll that has a small variation in electrical resistance in the semiconductive region and exhibits stable electrical resistance.

[0006] As a method for stabilizing the resistance value, Japanese Patent Application Laid-Open No. Hei 3-195572 proposes mixing EPDM and organopolysiloxane. However, as the demand for the stability of the resistance of the semiconductive region becomes higher, further stability of the resistance is required.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a semiconductive roll in which the variation in electrical resistance in a semiconductive region is extremely narrow and the electrical resistance is stable irrespective of molding conditions. With the goal.

[0008]

Means for Solving the Problems and Embodiments of the Invention As a result of intensive studies to achieve the above object, the present inventors have found that: (A) ethylene-propylene rubber and / or ethylene-propylene-diene rubber 98 parts by weight (B) the following average compositional formula _{(1) R n SiO (4} -n) / 2 (1) ( where, R is a substituted or unsubstituted monovalent hydrocarbon radical, n is 1.95～ A conductive EPDM / silicone rubber obtained by blending a conductive material such as conductive carbon black, conductive zinc oxide, or conductive titanium oxide with 2 to 95 parts by weight of an organopolysiloxane represented by the following formula: The average particle diameter of the composition is 0.1 to 100.
μm spherical silicone elastomer particles (A)
When a mixture of 5 to 200 parts by weight with respect to 100 parts by weight of the total of the component (B) is molded and cured to form a semiconductive silicone rubber layer on a cored bar,
In ^{0 3} ~10 ¹ 0 Ω · semiconductive region of cm, giving the electric resistance variation stable electric resistance of two orders of magnitude less,
The present inventors have found that they are excellent in weather resistance and hardly cause OPC contamination, so that a highly stable semiconductive roll particularly suitable for a developing roll, a transfer roll, a charging roll and the like can be obtained, and have accomplished the present invention.

Hereinafter, the present invention will be described in more detail. The semiconductive roll of the present invention comprises: (A) 5 to 98 parts by weight of ethylene / propylene rubber and / or ethylene / propylene / diene rubber; Compositional formula (1) R _n SiO _{(4-n) / 2} (1) (where R is a substituted or unsubstituted monovalent hydrocarbon group, and n is a positive number from 1.95 to 2.05) 2) to 95 parts by weight (C) 5 to 200 parts by weight based on 100 parts by weight of the total of components (A) and (B) of spherical silicone elastomer particles having an average particle diameter of 0.1 to 100 [mu] m. And (D) a conductive rubber composition containing a conductive material, wherein a semiconductive cured layer is formed.

The component (A) used in the semiconductive rubber composition is not particularly limited, and generally commercially available ethylene / propylene rubber (hereinafter, EPM),
EPDM can be used, but those having an ethylene content of 40 to 70% by weight and a Mooney viscosity at 100 ° C of 5 to 100, particularly 5 to 70 are preferably used. If the Mooney viscosity is too high, the dispersibility with the organopolysiloxane may deteriorate, and the stability of the resistance may be insufficient. In addition, as the diene monomer constituting EPDM, ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene, and the like can be mentioned.
As the degree of unsaturation, those having an iodine value in the range of 1 to 40 are preferable.

Next, the organopolysiloxane of the component (B) is represented by the following average composition formula (1). R _n SiO _{(4-n) / 2} (1)

R in the above formula (1) represents a substituted or unsubstituted monovalent hydrocarbon group, and usually has 1 to 10 carbon atoms, especially 1 to 10 carbon atoms.
To 8, specifically, methyl group, ethyl group, propyl group, butyl group, hexyl group, alkyl group such as octyl group, cyclopentyl group, cycloalkyl group such as cyclohexyl group, vinyl group, allyl group, An alkenyl group such as a propenyl group, an aryl group such as a cycloalkenyl group, a phenyl group or a tolyl group, an aralkyl group such as a benzyl group or a phenylethyl group, or a part or all of the hydrogen atoms of these groups is a chlorine atom or a fluorine atom Examples thereof include a halogenated hydrocarbon group substituted with an organic group such as a cyano group, a cyanated hydrocarbon group, and the like. Particularly generally, the organopolysiloxane in which the main chain is composed of dimethylsiloxane units or A phenyl group in the main chain of dimethylpolysiloxane,
Those into which a vinyl group, 3,3,3-trifluoropropyl group or the like is introduced can be suitably used. Also, n is 1.95-
It is a positive number of 2.05.

The degree of polymerization of the organopolysiloxane is preferably 100 or more. Polymerization degree 100
If the amount is less than the above, the mechanical strength of the cured product may be reduced, and the moldability may be poor. More preferably 100 to 100,00
0, more preferably 3,000 to 20,000.

In the present invention, as the rubber component, the component (A) and the organopolysiloxane of the component (B) are in a weight ratio of 98: 2 to 5:95, more preferably 95: 5 to 40. : 60, more preferably 90:10
Use a mixture of 50:50. In addition,
By using the components (A) and (B) together, the stability of the resistance of the semiconductive region is excellent, and the weather resistance is excellent.
There is an advantage that OPC contamination in the developing device is extremely small.

Next, the spherical silicone elastomer particles of the component (C) are components that act synergistically with the components (A) and (B) to stabilize the resistance of the semiconductive region. 0.1-100 μm, preferably 0.5-40
Use a μm. Particles having an average particle diameter of less than 0.1 μm are difficult to produce, and it is difficult to sufficiently obtain the effect of adding the particles. If the average particle diameter exceeds 100 μm, the mechanical strength of the cured rubber product may be impaired.

In this case, the type, grade, production method and the like of the spherical silicone elastomer particles are not particularly limited as long as they are cured products of the organopolysiloxane having the above-mentioned average particle size, and appropriate ones can be used. In particular,
Although there is no particular limitation on the spherical silicone elastomer particles, a method of curing a curable organopolysiloxane composition in a spray dryer at 230 to 300 ° C to obtain a granular silicone elastomer (Japanese Patent Application Laid-Open No. 59-96122) Or a curable organopolysiloxane composition, for example, an addition-reaction-type organopolysiloxane composition comprising a vinyl-containing organopolysiloxane and an organohydrogenpolysiloxane, is used to form emulsion particles in water using a surfactant. Particle size 20
μm or less, adding a platinum-based catalyst for an addition reaction, and curing the organopolysiloxane contained in the emulsion particles before spray drying or by the end of spray drying (Japanese Patent Application Laid-Open No. Sho 62).
No. 257939) can be used. Particularly, a vinyl group-containing organopolysiloxane and an organohydrogenpolysiloxane are formed into an emulsion using a surfactant, and the emulsion is subjected to an addition reaction with a platinum-based catalyst. Those produced by curing are preferred. In addition, as the elastomer particles, those whose surfaces are treated with silane, siloxane, or the like in advance or during the production thereof can also be used.

The amount of the spherical silicone elastomer particles to be used is 5 to 200 parts, preferably 10 to 150 parts, based on 100 parts (parts by weight, hereinafter the same) of the rubber component. If the amount of the spherical silicone elastomer particles is less than the above ratio, the effect of addition cannot be obtained. If the amount exceeds the above ratio, the mechanical strength of the cured product may decrease.

Next, as the conductive material of the component (D), a semiconductive rubber cured product having a volume resistivity of 10 ³ to 10 ¹⁰
As long as it becomes Ω · cm, its type and blending amount are not limited, but conductive carbon black, conductive zinc white,
It is preferable to use one or more of the conductive titanium oxides in combination.

Here, as the conductive carbon black, those commonly used in conductive rubber compositions can be used, for example, acetylene black, conductive furnace black (CF), superconductive furnace black (SCF), and extra carbon black. Conductive furnace black (XCF), conductive channel black (CC), furnace black and channel black heat-treated at a high temperature of about 1500 ° C. can be used. Specifically, as acetylene black, electrified acetylene black (manufactured by Denki Kagaku), Shaunigan acetylene black (manufactured by Shaunigan Chemical), etc., and as conductive furnace black, Continex CF (manufactured by Continental Carbon),
Vulcan C (made by Cabot Corporation), etc. has become Continex SC as superconductive furnace black.
F (manufactured by Continental Carbon), Vulcan SC (manufactured by Cabot) and the like. As extra conductive furnace black, Asahi HS-500 (manufactured by Asahi Carbon) and Vulcan XC-72 (manufactured by Cabot) include conductive channel black. Examples thereof include Colux L (manufactured by Degussa), and Ketjen Black EC and Ketjen Black EC-600JD (manufactured by Ketjen Black International), which are a kind of furnace black, can also be used. In addition,
Among these, acetylene black has a low impurity content and has a developed secondary structure structure and thus has excellent conductivity, and is particularly preferably used in the present invention. In addition, Ketjen Black EC, which exhibits excellent conductivity even at low loadings due to its outstanding specific surface area
And Ketjen Black EC-600JD can also be preferably used.

The amount of the conductive carbon black added is as follows:
1 to 50 parts, especially 5 to 100 parts of the above rubber component
It is preferable to set it to 20 parts. If the amount is less than 1 part, the desired conductivity may not be obtained. If the amount exceeds 50 parts, the electrical resistance of the obtained member may be less than 10 ³ Ω · cm. It may not be an area.

As the conductive zinc white, specifically, conductive zinc white manufactured by Honjo Chemical Co., Ltd. is preferably used, and 50 to 300 parts, especially 80 to 250 parts, of this is added. An electrical resistance of 10 ³ to 10 ¹⁰ Ω · cm can be obtained. If the amount is less than 50 parts, conductivity cannot be obtained, while if it exceeds 300 parts, the mechanical properties may be significantly deteriorated.
More preferably, it is 250 parts.

Further, examples of the white conductive titanium oxide include ET-500W (manufactured by Ishihara Sangyo Co., Ltd.). In this case, the basic composition is TiO ₂ · SnO ₂
Preferably, b is doped. In addition, the addition amount can be made the same as the addition amount of the above-described conductive zinc white.

In order to cure the rubber component, a curing agent is used. As the curing agent, vulcanization and curing are carried out by utilizing a radical reaction usually used for vulcanizing a conductive rubber composition. The curing mechanism is not limited as long as the curing agent is used, and various conventionally known curing agents can be used. For example, peroxides include alkyl peroxides such as di-t-butyl peroxide and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and aralkyl peroxides such as dicumyl peroxide. In addition to organic peroxides, sulfur vulcanization may be used. The amount of the curing agent used is a curing effective amount. In the case of an organic peroxide, the amount is preferably 0.1 to 10 parts based on 100 parts of the rubber component.

The rubber composition may contain reinforcing silica fillers such as silica hydrogel (hydrous silicic acid) and silica aerogel (silicic anhydride-fumed silica), clay, calcium carbonate, diatomaceous earth, and titanium dioxide, if necessary. Fillers, low-molecular-weight siloxane esters, dispersants such as silanols such as diphenylsilanediol, heat-resistance improvers such as iron oxide, cerium oxide, and iron octylate; and various carbon funks for improving adhesiveness and moldability. It is also possible to add and mix optional silane and a halogen compound for imparting flame retardancy.

The semiconductive roll of the present invention has a semiconductive cured layer of the above rubber composition formed on a cored bar. In this case, the material and dimensions of the cored bar depend on the type of roll. It can be selected as appropriate. In addition, the molding and curing methods of the rubber composition can also be appropriately selected, for example, can be molded by a method such as pressure molding, transfer molding, extrusion molding, injection molding, calender molding, and the curing method is selected according to the type of the curing agent. Is done.

It is effective that the semiconductive cured layer has a resistance of 1 × 10 ³ to 1 × 10 ¹⁰ Ω · cm between the surface and the core metal. In this range, the variation of the electric resistance is within two digits, so that it is particularly suitable as a semiconductive roll such as a charging roll, a transfer roll, a developing roll, and a paper feed roll in a developing device.

[0027]

According to the semiconductive roll of the present invention, the electric resistivity in the semiconductive region is not influenced by the molding conditions, the dispersion is extremely small, the molding processability is improved,
It has excellent vulcanization characteristics and rubber elasticity.

[0028]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, all parts are parts by weight.

[Examples 1 and 2, Comparative Examples 1 to 3] EPDM
(Trade name: EP-43, manufactured by Nippon Synthetic Rubber Co., Ltd.), the average degree of polymerization of 99.85 mol% of dimethylsiloxane units and 0.15 mol% of methylvinylsiloxane units is about 8000.
Methylvinylpolysiloxane, silica R-972 having a hydrophobicized surface (trade name, manufactured by Nippon Aerosil Co., Ltd.), liquid paraffin PW-380 (trade name, manufactured by Idemitsu Kosan Co., Ltd.), antioxidant (Nocrack MB Ouchi Shinko Chemical Co., Ltd.), spherical silicone elastomer particles K
MP594 (particle size: 3 to 10 μm, trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) was blended in the amount shown in Table 1, and Ketjen Black was further added and kneaded. Then, the organic peroxide 2,5
-Dimethyl-2,5-di (t-butylperoxy) hexane was kneaded, and the resulting compound was used to form a mixture having a diameter of 20%.
mm rolls were formed. The molding temperature at this time is 1
The molding pressure was 30 kgf / cm ² at 65 ° C. for 15 minutes. Next, the electrical characteristics of the obtained roll were measured. Table 1 shows the results. In addition, the electrical characteristics measured the resistance between the electrode 3 and the roll core 2 by making the roll 1 contact the electrode 3 of 7 mm width as shown in FIG. The dispersion was evaluated at 20 measurement points in the axial direction. in this case,
The measuring voltage was 100 V, and the measuring device 4 was Advantest Digital Ultra High Resistance Meter R8340. Also, OP
The contamination to C was evaluated by incorporating the obtained roll into a laser printer. Table 1 shows the results.

[0030]

[Table 1]

Examples 3, 4 and Comparative Example 4 Ketjen black and conductive zinc white (trade name, manufactured by Honjo Chemical Co., Ltd.) or white conductive titanium oxide ET-500W (trade name, manufactured by Ishihara Sangyo Co., Ltd.) ) Was added in the proportions shown in Table 2, and the other characteristics were evaluated in the same manner as in Example 1. Table 2 shows the results.

[0032]

[Table 2]

From the results shown in Tables 1 and 2, the blends of EPDM, organopolysiloxane and spherical silicone elastomer particles (Examples 1 to 4) exhibited more stable electric resistance values in the semiconductive region, and showed that Was also less.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an apparatus used to measure electrical properties of a semiconductive roll.

[Explanation of symbols]

 1 roll 2 core metal 3 electrode 4 resistance measuring instrument

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/08 501 G03G 15/08 501D 4J002 15/16 103 15/16 103 15/20 103 15/20 103 (72) Inventor Masayuki Yoshida 1-chome, Hitomi, Matsuida-cho, Usui-gun, Gunma Prefecture F-term (reference) 2E003 CC05 2H032 AA05 2H033 AA02 BB06 BB29 2H077 AD02 AD06 FA21 FA25 3J103 AA02 FA15 GA02 GA33 GA52 GA74 HA05 HA12 HA20 HA41 HA47 HA53 4J002 BB151 CP032 CP033 CP082 CP092 DA036 DE106 DE136 FA083 FD010 FD116 FD140 GQ02

Claims (3)

[Claims] (A) 5 to 98 parts by weight of an ethylene / propylene rubber and / or an ethylene / propylene / diene rubber (B) The following average composition formula (1) R _n SiO _{(4-n) / 2} (1) ( However, R is a substituted or unsubstituted monovalent hydrocarbon group, and n is a positive number from 1.95 to 2.05.) 2 to 95 parts by weight of an organopolysiloxane represented by the following formula: The spherical silicone elastomer particles having a particle size of 0.1 to 100 µm, and the semiconductivity of a conductive rubber composition containing (D) a conductive material, based on a total of 100 parts by weight of the components (A) and (B). A semiconductive roll, wherein a cured rubber layer is formed on a cored bar. 2. The semiconductive roll according to claim 1, wherein the conductive material is at least one selected from conductive carbon black, conductive zinc oxide, and conductive titanium oxide. 3. The semiconductive rubber cured product has a volume resistance of 10 ^3.
The semiconductive roll according to claim 1, wherein the semiconductive roll has a pressure of ¹⁰ to 10 ¹⁰ Ω · cm.