JP2008163282A - Method for producing semiconductive silicone rubber member for electrophotographic apparatus, and roll and belt for electrophotographic apparatus having the silicone rubber member - Google Patents

Abstract

A production method for obtaining a silicone rubber member for an electrophotographic apparatus in which a low molecular siloxane component is reduced is provided.
(A) 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 number from 1.95 to 2.05.)
100 parts by mass of an organopolysiloxane represented by
(B) Conductive material Amount to impart semiconductivity, and (C) Curing agent (A) A silicone rubber composition containing an amount capable of curing the component is molded and cured to obtain a molded cured product,
A method for producing a semiconductive silicone rubber member for an electrophotographic apparatus, wherein the obtained molded cured product is treated at a temperature of 80 to 180 ° C. under a pressure of 5.0 × 10 ⁴ Pa or less.
[Selection figure] None

Description

  The present invention relates to a method for producing a semiconductive silicone rubber member for an electrophotographic apparatus, a silicone rubber member obtained by the production method, and a roll and belt for an electrophotographic apparatus having the silicone rubber member.

  Silicone rubber is used for various rolls (for example, developing rolls, toner transports) arranged around OPC (organic conductor) drums used in various electrophotographic apparatuses using electrophotographic processes such as copying machines, facsimiles, and printers. Sponge roll, cleaning sponge roll, fixing roll) or various belts (for example, developing belt, fixing belt) are used as constituent members.

  The silicone rubber member contains a small amount of a low-molecular siloxane component contained in an organopolysiloxane usually used as a raw material in an uncrosslinked state. When the low molecular weight siloxane component is transferred from the silicone rubber member to the OPC drum or toner, it may cause defects such as white streaks or blurring in the printed image. As a method for suppressing the migration of such low-molecular siloxane components, a raw material organopolysiloxane having a low low-molecular-weight siloxane content is used as much as possible, and silicone rubber powder with a low-molecular-weight siloxane content is added to this. A method of reducing the amount of low molecular siloxane in the obtained silicone rubber member is known (Patent Document 1). In addition, a method has been proposed in which low molecular siloxane is adsorbed to a filler or the like to prevent the low molecular siloxane from moving from the silicone rubber member to the outside and adhering to other members (Patent Document 2).

  Usually, silicone rubber is required to be heat-treated for secondary crosslinking. In the case of addition crosslinking, the purpose is to add an aliphatic unsaturated group (such as a vinyl group) bonded to the main chain of an organopolysiloxane used as a base polymer and an organohydrogenpolysiloxane used as a crosslinking agent. It is to increase the production rate of silethylene bonds formed by the reaction (hydrosilylation), and as a result, to improve compression set. In the case of organic peroxide crosslinking, it is possible to remove the decomposition residue of the organic peroxide generated by heat curing and to prevent discoloration. Further, in the case of a sponge foam molded product, it is essential to remove the decomposition residue of the foaming agent and make the internal pressure of the foam uniform to enhance the dimensional stability of the foam. Further, a common purpose for addition crosslinking and organic peroxide crosslinking is to reduce the low molecular siloxane component. The reduction of the low molecular siloxane content is important not only for preventing the occurrence of the above-mentioned image defects, but also for suppressing contact failures such as switches and improving the dimensional stability of the molded product.

  Normally, the temperature conditions for secondary crosslinking are determined according to the decomposition temperature of the target substance to be removed by volatilization and the vapor pressure at the processing temperature of the target substance. There were many cases. As the conditions for secondary crosslinking described in the literature, the condition of heating at 200 ° C. for about 4 hours is often recommended (Patent Document 3). This is because, when secondary crosslinking is performed at a temperature exceeding 200 ° C., the phenomenon that the Si—O bond in the silicone rubber is broken due to thermal degradation and low molecular siloxane is generated becomes remarkable.

  However, in electrophotographic apparatuses, the problem of contamination and image defects caused by bleeding out of low-molecular-weight siloxane from a silicone rubber member and shifting to an OPC drum or toner has not yet been sufficiently solved, and further improvements are made. Is required.

Japanese Patent No. 2748215 Japanese Patent No. 3324413 "Silicone Handbook" edited by Kunio Ito, Nikkan Kogyo Shimbun, August 31, 1990, pages 326 and 612

  Accordingly, an object of the present invention is to provide a production method capable of obtaining a silicone rubber member for an electrophotographic apparatus in which the production method of the silicone rubber member is improved and the low molecular siloxane component is further reduced.

  As a result of intensive research on the conditions for secondary cross-linking treatment of silicone rubber, one of the purposes of the secondary cross-linking treatment is to reduce the low-molecular siloxane components present in the silicone rubber after the primary cross-linking. For this reason, it has been desired to set the secondary crosslinking temperature as high as possible not exceeding 200 ° C. Under such conditions, the main chain of the organopolysiloxane is cleaved. As a result of finding that it promotes the formation and studying the secondary cross-linking conditions there, the production method of the present invention has been developed.

That is, the present invention provides (A) 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 number from 1.95 to 2.05.)
100 parts by mass of an organopolysiloxane represented by
(B) Conductive material A silicone rubber composition containing an amount that imparts semiconductivity and (C) a curing agent (A) that can cure the component is molded on a substrate with or without an intermediate layer. Cured to obtain a molded cured product,
Provided is a method for producing a semiconductive silicone rubber member for an electrophotographic apparatus, wherein the obtained molded cured product is treated at a temperature of 80 to 180 ° C. under a pressure of 5.0 × 10 ⁴ Pa or less. It is.

  The production method of the present invention can effectively remove free silicone oil components (low molecular siloxanes and oligomers) such as low molecular siloxane while suppressing thermal degradation of the silicone polymer in secondary crosslinking. Accordingly, since the silicone rubber member obtained has such a component significantly reduced, when it is used as a silicone rubber member for an electrophotographic apparatus, the silicone component migrates to the OPC drum or the toner, and white streaks or fading occurs on the image. Defects such as are unlikely to occur.

  Since the silicone rubber member obtained by the production method of the present invention has a significantly reduced low-molecular siloxane component, the contamination of the OPC drum is reduced and a conventional protective film such as a urethane coat is unnecessary as a contamination countermeasure. It is possible to make such a contamination protective film thinner.

Hereinafter, the present invention will be described in detail.
[Semiconductive silicone rubber member for electrophotographic equipment]
The electrophotographic apparatus is an apparatus that processes an image by an electrophotographic process, and examples thereof include a copying machine, a facsimile, and a printer.

  The semiconductive silicone rubber member for an electrophotographic apparatus of the present invention is placed in a state where it is in direct or indirect contact with an OPC and a toner during operation in the electrophotographic apparatus. It is a member constituting an electrophotographic belt.

  In the case of the present invention, the roll for an electrophotographic apparatus comprises a roll core metal and at least one semiconductive silicone rubber layer (semiconductive silicone) provided on the outer peripheral surface of the core metal with or without an intermediate layer. Example of rubber member). Examples of the electrophotographic roll include a developing roll, a toner conveying sponge roll, a cleaning sponge roll, and a fixing roll.

  In the case of the present invention, the belt for an electrophotographic apparatus comprises a belt-like base material and at least one silicone rubber layer (an example of a semiconductive silicone rubber member) provided on the base material with or without an intermediate layer. ). Examples of the belt for an electrophotographic apparatus include a developing belt and a fixing belt.

[Silicone rubber composition]
First, the silicone rubber composition used in the production method of the present invention will be described. In the following description, unless otherwise specified, “part” means “part by mass”.

-(A) Organopolysiloxane-
The organopolysiloxane of component (A) is represented by the following average composition formula (1):
R _n SiO _{(4-n) / 2} (1)

In the average composition formula (1), examples of the substituted or unsubstituted monovalent hydrocarbon group represented by R ¹ include alkyl groups such as methyl group, ethyl group, propyl group, butyl group, hexyl group and dodecyl group, and cyclohexyl. A cycloalkyl group such as a group, an alkenyl group such as a vinyl group, an allyl group, a butenyl group, a hexenyl group, an aryl group such as a phenyl group or a tolyl group, an aralkyl group such as a β-phenylpropyl group, or a carbon atom of these groups A chloromethyl group, a trifluoropropyl group, a cyanoethyl group or the like in which a part or all of the hydrogen atoms bonded to is substituted with a halogen atom, a cyano group or the like, and has 1 to 12 carbon atoms, particularly 1 to 8 carbon atoms. Are preferred. A plurality of R ¹ present in the organopolysiloxane may be the same or different. Moreover, a is a positive number of 1.95 to 2.05. The organopolysiloxane is preferably end-capped with a trimethylsilyl group, a dimethylvinyl group, a dimethylhydroxysilyl group, a trivinylsilyl group, or the like.

The organopolysiloxane preferably has at least two alkenyl groups in the molecule, and preferably 0.001 to 5 mol%, particularly 0.01 to 0.5 mol% of alkenyl groups, particularly vinyl groups, of R ^1. .

  In particular, when a combination of a platinum catalyst and an organohydrogenpolysiloxane is used as the curing agent for the component (C), an organopolysiloxane containing such an alkenyl group is usually used.

  This organopolysiloxane can be obtained by methods well known to those skilled in the art, for example, by cohydrolytic condensation of one or more organohalogenosilanes selected to have the required molecular structure and degree of polymerization, or It can be obtained by ring-opening polymerization of cyclic polysiloxane (such as siloxane trimer or tetramer) using an alkaline or acidic catalyst. This organopolysiloxane is basically a linear diorganopolysiloxane, but may be partially branched. Further, it may be a mixture of two or more different molecular structures.

The organopolysiloxane preferably has a viscosity at 25 ° C. of 100 mm ² / s or more. The preferred viscosity for liquid LIMS (for injection molding) material is 100 to 100,000 mm ² / s. The degree of polymerization is preferably 5 or more, particularly preferably 10 or more, and more preferably 50 to 1,000. The viscosity preferably used in the millable material is 100,000 to 10,000,000 mm ² / s, the degree of polymerization is preferably 100 or more, particularly preferably 3,000 or more, and the upper limit is preferably 100,000, more preferably 10,000.

-(B) Conductivity imparting agent-
Next, the conductivity imparting agent of the component (B) will be described. The type of the conductivity-imparting agent is not limited, but conductive carbon black, conductive metal oxide particles such as conductive zinc white and conductive titanium oxide can be used, and the conductivity-imparting agent can be used alone. Two or more types may be used in combination.

  As the conductive carbon black, those usually used in conductive rubber compositions can be used, such as acetylene black, conductive furnace black (CF), super conductive furnace black (SCF), and extra conductive furnace black. (XCF), conductive channel black (CC), furnace black and channel black heat-treated at a high temperature of about 1500 to 3000 ° C. Specific examples of commercially available products (trade names) include Denka Black (manufactured by Electrochemical Co., Ltd.) and Shaunigan Acetylene Black (manufactured by Shaunigan Chemical Co., Ltd.) as acetylene black. Examples of the conductive furnace black include CONTINEX CF (manufactured by Continental Carbon) and Vulcan C (manufactured by Cabot). Examples of super conductive furnace black include CONTINEX SCF (manufactured by Continental Carbon) and Pulcan SC (manufactured by Cabot). Examples of the extra conductive furnace black include Asahi HS-500 (Asahi Carbon Co., Ltd.), Pulcan XC-72 (Cabot Corp.), and the like. Examples of the conductive channel black include Kourax L (manufactured by Degussa). Further, carbon blacks ENSACO260G, ENSACO250G, ENSACO210G (manufactured by TIMCAL) manufactured by an oil combustion method that does not include a quenching process (MMM Process method), and the like can be given. Further, Ketjen Black EC-300JD and Ketjen Black EC-600JD (Ketjen Black International Co., Ltd.), which are a kind of furnace black, can also be used. In furnace black, the amount of impurities, particularly sulfur and sulfur compounds, is 6000 ppm or less, more preferably 3000 ppm or less in terms of the concentration of elemental sulfur. Among these, acetylene black has a low impurity content and has a developed secondary structure structure, so that it has excellent conductivity and is particularly preferably used in the present invention. In addition, ketjen black or the like showing excellent conductivity even at a low filling amount can be preferably used because of its excellent specific surface area.

The addition amount of the conductivity imparting agent of the component (B) is an amount sufficient to give the required semiconductivity to the cured rubber of the conductive silicone rubber composition. Specifically, the volume resistivity of the cured product is The amount is 0.1Ω · m to 10 ¹⁴ Ω · m. Therefore, although an appropriate addition amount changes with kinds of the electroconductivity imparting agent to be used, those skilled in the art can easily determine it by trying a simple test.

  When the conductivity imparting agent is carbon black, it is preferably 1 to 200 parts, more preferably 5 to 50 parts, relative to 100 parts of the organopolysiloxane of the component (A) described above. If the addition amount is too large, it may be difficult to physically mix with other components, particularly the component (A), and the mechanical strength of the cured product may be reduced, or the desired rubber elasticity may be obtained. It may not be possible.

  When the conductivity-imparting agent is conductive metal oxide-based particles, the recommended amount of addition is preferably 30 to 200 parts, particularly 50 to 200 parts per 100 parts of component (A) because the specific gravity of the particles is high. .

-(C) Curing agent-
As the curing agent for component (C), a combination of a platinum-based catalyst and an organohydrogenpolysiloxane (addition crosslinking type curing agent) and an organic peroxide catalyst (radical crosslinking type curing agent) can be used. The curing agent is blended in an effective amount for curing the silicone rubber composition.

  The combination of a platinum-based catalyst and an organohydrogenpolysiloxane is conventionally known as a curing agent for addition-curable silicone compositions. In this case, the organopolysiloxane of component (A) is usually as described above. And those having at least two alkenyl groups in the molecule.

The molecular structure of this organohydropolyenepolysiloxane may be linear, branched or cyclic, but preferably has a degree of polymerization of 300 or less, and the end is blocked with a dimethylhydrosilylsilyl group Diorganopolysiloxane, copolymer of dimethylsiloxane unit, methylhydrodienesiloxane unit and terminal trimethylsiloxy unit, dimethylhydrodienesiloxane unit (H (CH ₃ ) ₂ SiO _0.5 unit) and SiO ₂ unit Low viscosity fluid, 1,3,5,7-tetrahydrodiene-1,3,5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7-trihydrodiene-1,3,5, 7-tetramethylcyclotetrasiloxane, 1,5-dihydrodiene-3,7-dihexyl-1,3,5,7-tetra Such as chill cyclotetrasiloxane are exemplified.
The addition amount of the organohydropolyenepolysiloxane is desirably such that the hydrogen atom directly connected to the silicon atom is 50 to 500 mol% with respect to the alkenyl group of the organopolysiloxane of the component (A).

  As the platinum catalyst to be combined with the organohydrogenpolysiloxane, any known catalyst can be used. For example, platinum element alone, platinum complex, platinum compounds such as chloroplatinic acid, alcohol of chloroplatinic acid, and the like. Examples thereof include compounds, aldehyde compounds, ether compounds, complexes with various olefins, and the like. The addition amount of the platinum-based catalyst is preferably in the range of 1 to 2,000 ppm (mass basis) as platinum atoms with respect to the organopolysiloxane of component (A).

  On the other hand, examples of the organic peroxide used as the curing agent for the component (C) include di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, Examples thereof include alkyl peroxides such as mill peroxide. The addition amount of the organic peroxide is preferably 0.1 to 10 parts with respect to 100 parts of the organopolysiloxane of the component (A).

  As the curing agent for component (C), the addition crosslinking type curing agent and the organic peroxide may be used in combination to cause both addition type crosslinking and radical reaction type crosslinking. When the silicone rubber composition used is a liquid material, an addition crosslinking type curing agent is recommended as the curing agent for the component (C).

-Other ingredients-
As long as the objective and effect of this invention are not impaired, the other component demonstrated below can be added to the silicone rubber composition used for this invention as needed.

・ Reinforcing silica fine powder:
A typical and preferred reinforcing fine silica powder is a fine silica powder. Silica fine powder is necessary to obtain a cured rubber having excellent mechanical strength. For this purpose, the specific surface area is preferably 10 m ² / g or more, more preferably 50 to 400 m ² / g. . Examples of the silica fine powder include fumed silica (dry silica) and precipitated silica (wet silica), and fumed silica (dry silica) is preferable. These surfaces may be hydrophobized with organopolysiloxane, organopolysilazane, chlorosilane, alkoxysilane, or the like. Examples of commercially available reinforcing silica that can be used include Aerosil 130,200,300,380 (trade name, manufactured by Nippon Aerosil Co., Ltd.), Cab-O-sil MS-5, MS-7, HS-5, HS-7 (trade name) , Manufactured by Cabot Corporation), SantocelFRC, CS (trade name, manufactured by Monsanto), Nipsil VN-3 (trade name, manufactured by Nippon Silica Kogyo Co., Ltd.), and the like. These silicas may be used alone or in combination of two or more. Although the amount of silica fine powder added is not strict, it is preferably in the range of 1 to 50 parts per 100 parts of organopolysiloxane in consideration of the reinforcing effect and workability and influence on conductivity. .

・ Other additives:
In addition, colorants, heat resistance improvers such as iron octylate, halogen compounds that impart flame retardancy, acid acceptors, iron oxide, cerium oxide, thermal conductivity improvers, mold release agents, fillers as extenders (For example, pulverized crystalline silica or diatomaceous earth fine powder). Furthermore, dispersants such as alkoxysilane, dimethylsiloxane oil having a polymerization degree lower than that of the organopolysiloxane of component (A), silanol (for example, silanol-blocked low molecular siloxane such as diphenylsilanediol), adhesion and molding processing Examples thereof include various carbon functional silanes for improving the properties, and cured and uncured various olefin elastomers that do not inhibit the crosslinking of the silicone component of the present composition.

-Preparation-
The silicone rubber composition of the present invention can be obtained by uniformly mixing the above-described components using a mixer such as a two-roll mill, a Banbury mixer, a dough mixer (kneader), a Shinagawa mixer, or a planetary mixer.

[Manufacturing method of silicone rubber member]
-Primary cross-linking According to the production method of the present invention, the silicone rubber composition prepared as described above is first molded and cured on a substrate with or without an intermediate layer to obtain a molded cured product. .

  The molding and curing method used here may be a known method and is not particularly limited. A foam curing method can also be used. The method of heating and curing is not particularly limited, and any known method may be used as long as it is a method of applying heat necessary for crosslinking the silicone component of the composition. The molding method is not particularly limited, such as continuous vulcanization by extrusion molding, press molding, and mold molding by injection molding. Molding for the primary crosslinking is performed at a heating temperature of 70 to 500 ° C., particularly 120 to 300 ° C., and a heating time of several seconds to 1 hour, particularly 10 seconds to 30 minutes. Preferably there is.

  More specifically, the silicone rubber composition is formed into a layer (sheet or film) on a substrate with or without an intermediate layer, and then heated and cured. Examples of the intermediate layer include layers such as a primer and a rubber elastic adhesive, and are applied in advance. The base material is a core metal, a metal belt, a resin belt or the like when producing a roll for an electrophotographic apparatus, and a belt-like base material when producing a belt for an electrophotographic apparatus. A layered silicone rubber member is formed on the substrate by primary curing.

Secondary cross-linking The molded cured product obtained as described above is then treated at a temperature of 80 to 180 ° C. under a pressure of 5.0 × 10 ⁴ Pa or less.

As specifically recommended conditions, the molded cured product is under a low pressure of 5.0 × 10 ⁴ Pa (380 Torr) or less, preferably 1.0 × 10 ⁴ Pa (76 Torr) or less, and 80 to 180 ° C., Preferably, heat treatment under reduced pressure is performed at a temperature of 80 to 150 ° C. More preferably, the low pressure heat treatment conditions are good under a low pressure of 2.0 × 10 ³ Pa (15 Torr) or less and a temperature of 80 to 180 ° C. The time for the heat treatment under reduced pressure may be appropriately selected according to the pressure and temperature, but is generally preferably 10 minutes or more, and more preferably 60 minutes or more.

The lower the degree of vacuum, the more volatile components such as low molecular weight siloxane can be removed, and the oxidation of silicone by oxygen can be prevented. Accordingly, there is no particular lower limit for the pressure, but it is usually about 1.0 × 10 ^{2 to} 1.0 × 10 ³ Pa in practice. Further, if the treatment temperature is low, the silicone polymer is less deteriorated, but the removability of the volatile low molecular silicone component is also lowered.

  The above-mentioned reduced pressure heat treatment method is not particularly specified, but specifically, for example, a commercially available reduced pressure dryer, vacuum dryer, heat treatment dryer using radiant heat or the like, for example, a vacuum low temperature dryer DRV420DA manufactured by ADVANTEC Co., Ltd. (Product name) can be used.

The silicone rubber member thus formed is semiconductive. That is, the volume resistivity is in the range of 0.1 to 10 ¹⁴ Ω · m, and it is useful as a constituent member of a roll for an electrophotographic apparatus or a belt.

  On the semiconductive silicone rubber layer as a silicone rubber member formed on the substrate with or without an intermediate layer as described above, further, if necessary, protection, prevention of low molecular siloxane component bleed, Another layer such as a urethane-based coating layer, a silicone-based coating layer, or the like may be formed for preventing scratches, improving slipperiness, imparting abrasion resistance, or other purposes.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not limited to the following Example. The parts shown in Examples and Comparative Examples all represent parts by mass, and the viscosity is a value measured with a Brookfield rotary viscometer at 25 ° C.

Example 1
-Consisting of 99.825 mol% of dimethylsiloxane units and 0.15 mol% of methylvinylsiloxane units, both ends of the molecular chain are blocked with 0.025 mol% of dimethylvinylsilyl groups, and the viscosity is 1 x 10 ⁷ mm ² / 100 parts of organopolysiloxane,
-10 parts of fumed silica (Nippon Aerosil Co., Ltd.) with a specific surface area of 200 m ² / g,
-Two parts silanol group-terminated dimethylpolysiloxane polymer having an average degree of polymerization of 3 to 10 as a dispersant was kneaded using a kneader, and then heat treated at 160 ° C for 2 hours to prepare a base compound A.

  Next, to 100 parts of this base compound, 12 parts of acetylene black DENKA BLACK (average particle size 40 nm, trade name, manufactured by Electrochemical Co., Ltd.) as a conductivity-imparting agent is added and dispersed in a two-roll mill, and conductive rubber is added. Compound A was created.

  Next, methyl hydrogen polysiloxane (polymerization) having silicon atom-bonded hydrogen atoms (that is, Si—H groups) at both ends and in the middle (that is, non-terminal) of the molecular chain as a cross-linking agent was added to 100 parts of this conductive rubber compound A. 17 parts, 2.1 parts of silicon atom-bonded hydrogen atom 0.0060 mol / g), 2.1 parts of reaction control agent, 0.1 part of ethynylcyclohexanol, 0.1 part of platinum catalyst (Pt concentration 1%) It added with the roll mill and prepared the curable silicone rubber composition.

The composition thus obtained was coated around a core metal having a diameter of 6 mm with a thickness of 6 mm, and formed into a roll shape having a diameter of 18 mm and a length of 50 mm as a whole, and was cured. The composition was also molded into a 2 mm thick sheet and cured. The molding and curing conditions at this time were press-cured at 120 ° C. for 15 minutes, and then the secondary crosslinking treatment was performed at 150 ° C. under a reduced pressure of 1.0 × 10 ³ Pa (7.5 Torr). It was heating for hours.

  A roll having a cured silicone rubber layer formed on the surface by the above curing treatment (referred to as a silicone rubber roll) is shaved with a polishing machine until the diameter becomes 16 mm, and the surface is polished to have a surface roughness of 10 μm or less. A smooth roll was obtained. Next, the contamination property of this silicone rubber roll and the depression due to compression were evaluated by the following methods.

・ Contamination:
The contamination property of the silicone rubber roll, that is, the contamination of the OPC drum by the silicone component that may bleed from the cured silicone rubber layer of the roll was evaluated as follows.
The toner cartridge was once removed from the Canon laser printer (LaserPress 4150PS), and the surface of the OPC drum was left for 24 hours in a state where the surface of the silicone rubber layer of the roll was pressed by applying a force of 1 kg to both ends of the silicone rubber roll. Thereafter, the toner cartridge was returned to the printer, and the entire surface was printed with gray. When the silicone component is bleed from the silicone rubber roll and transferred to the OPC drum due to the pressing, contamination occurs in a form in which the pressed surface of the silicone roll is reflected on the printed paper. Continuous printing was performed, and the number of printed sheets until the pressing trace disappeared visually from the printing paper was measured.

・ Dent:
The silicone rubber roll pressed against the OPC drum as described above was removed, and one hour after releasing from the compression by pressing, the amount of dent (that is, the depth of the dent) generated on the silicone rubber roll by pressing the OPC drum was measured. The amount of dents is an important characteristic when the silicone rubber roll is used as a developing roll. This is because when toner adheres to the dent, the toner layer in that portion becomes thicker than the surrounding area, resulting in non-uniform thickness of the toner layer and variations in print density. Therefore, the smaller the dent, the better the developing roll.

  In addition, physical properties and low molecular siloxane content were evaluated as follows using the 2 mm thick silicone rubber sheet prepared above.

・ Physical characteristics:
According to JIS K 6249, hardness (durometer type A) and 180 ° C./22 h compression set were measured. The rebound resilience was measured according to JIS K 6255.

・ Low molecular siloxane content:
After 1 g of a small piece of a silicone rubber sheet was immersed in an acetone solution containing 20 ppm of n-tetradecane for 8 hours and extracted, the temperature was increased from 50 ° C. to 270 ° C. at a temperature increase rate of 10 ° C./min. It measured on the conditions to heat up. The column used was DB1701 manufactured by J & W and He was used as the carrier gas. The concentration of the low molecular siloxane was calculated by converting the peak area using n-tetradecane as a standard substance.
The above evaluation results are shown in Table 1.

[Example 2]
The sheet and rolls were removed in the same manner as in Example 1 except that the degree of vacuum in the secondary crosslinking conditions described in Example 1 was changed from 1.0 × 10 ³ Pa (7.5 Torr) to 1.0 × 10 ⁴ Pa (76 Torr). Obtained.

Example 3
The sheet and rolls were removed in the same manner as in Example 1 except that the degree of vacuum in the secondary crosslinking conditions described in Example 1 was changed from 1.0 × 10 ³ Pa (7.5 Torr) to 5.0 × 10 ⁴ Pa (380 Torr). Obtained.

(Example 4)
A sheet and a roll were obtained in the same manner as in Example 1 except that the temperature of the secondary crosslinking conditions described in Example 1 was changed from 150 ° C to 80 ° C.

(Comparative Example 1)
A sheet and a roll were obtained in the same manner as in Example 1 without carrying out the secondary crosslinking conditions described in Example 1.

[Comparative Example 2]
Sheets and rolls were obtained in the same manner as in Example 1 except that the secondary crosslinking conditions described in Example 1 were changed to 230 ° C / 4h heat treatment at normal pressure instead of heat treatment under reduced pressure.

[Comparative Example 3]
Sheets and rolls were obtained in the same manner as in Example 1 except that the secondary crosslinking conditions described in Example 1 were changed to 200 ° C / 4h heat treatment at normal pressure instead of heat treatment under reduced pressure.

[Comparative Example 4]
Sheets and rolls were obtained in the same manner as in Example 1 except that the secondary crosslinking conditions described in Example 1 were changed to 180 ° C./4 h heat treatment at normal pressure instead of heat treatment under reduced pressure.

[Comparative Example 5]
Sheets and rolls were obtained in the same manner as in Example 1 except that the secondary crosslinking conditions described in Example 1 were changed to 200 ° C./24 h heat treatment at normal pressure instead of heat treatment under reduced pressure.

[Comparative Example 6]
Sheets and rolls were obtained in the same manner as in Example 1 except that the secondary crosslinking conditions described in Example 1 were changed to 150 ° C./24 h heat treatment at normal pressure instead of heat treatment under reduced pressure.

  Evaluation similar to Example 1 was performed using the silicone rubber roll and silicone rubber sheet obtained in Example 2-4 and Comparative Example 1-6. The results are shown in Tables 1 and 2.

[Notes on Table 1]
1) Material hardness, impact resilience, compression set, and amount of low molecular siloxane are data after secondary crosslinking.
2) Dn: Cyclic siloxane composed of n [(CH ₃ ) ₂ SiO] units

[Notes on Table 2]
1) Material hardness, impact resilience, compression set, and amount of low molecular siloxane are data after secondary crosslinking except for Comparative Example 1.
2) Dn: Cyclic siloxane composed of n [(CH ₃ ) ₂ SiO] units

  As shown in Tables 1 and 2, the low-molecular siloxane was efficiently removed from the roll subjected to the heat treatment under the secondary crosslinking conditions by the production method of the present invention, and the OPC drum contamination (printing stains) due to the migration of the silicone component to the OPC drum. It is clear that the number of sheets) is reduced, the dents are small, and the rolls are well reduced.

  The semiconductive silicone rubber member for an electrophotographic apparatus obtained by the production method of the present invention is particularly useful as a rubber member used in direct or indirect contact with an OPC drum or toner, for example, for an electrophotographic apparatus. The constituent members of various rolls and various belts are typical. Specifically, it is useful for constituent members such as a developing roll, a developing belt, a toner conveying sponge roll, a transfer roll, a transfer belt, a fixing roll, and a fixing belt.

Claims (9)

(A) 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 number from 1.95 to 2.05.)
100 parts by mass of an organopolysiloxane represented by
(B) Conductive material Amount to impart semiconductivity and (C) Curing agent (A) A silicone rubber composition containing an amount capable of curing the component is layered on the substrate with or without an intermediate layer Molded and cured to form a molded cured product,
A method for producing a semiconductive silicone rubber member for an electrophotographic apparatus, wherein the obtained molded cured product is treated at a temperature of 80 to 180 ° C. under a pressure of 5.0 × 10 ⁴ Pa or less.   The manufacturing method according to claim 1, wherein the substrate is a core metal of a roll for an electrophotographic apparatus or a belt-shaped substrate of a belt for an electrophotographic apparatus.   The silicone rubber composition is formed into a layer on the outer peripheral surface of the core metal as a base material with or without an intermediate layer and cured to form a cured silicone rubber layer, and the cured silicone rubber layer is decompressed under the above conditions. The manufacturing method according to claim 1, comprising heat-treating under.   4. The manufacturing method according to claim 2, wherein the roll for an electrophotographic apparatus is a developing roll, a toner conveying sponge roll, a cleaning sponge roll, or a fixing roll.   The belt for an electrophotographic apparatus comprises a belt-like base material and at least one silicone rubber layer provided on the base material with or without an intermediate layer, and the semiconductive silicone rubber The manufacturing method according to claim 2, wherein the member is the silicone rubber layer.   6. The method according to claim 2, wherein the electrophotographic belt is a developing belt or a fixing belt.   A semiconductive silicone rubber member for an electrophotographic apparatus produced by the production method according to claim 1.   A roll for an electrophotographic apparatus, comprising the semiconductive silicone rubber member according to claim 7.   A belt for an electrophotographic apparatus comprising the semiconductive silicone rubber member according to claim 7.