JP4920147B2 - Semiconductive roll - Google Patents

Description

表１に示す結果より、球状シリコーンエラストマー粒子を配合したもの（実施例１〜３）は、該エラストマー粒子を配合しないものや少量配合したもの（比較例１，２）に比べて、半導電領域においてより安定した電気抵抗値を示し、そのバラツキが１桁程度であることが確認された。また、ミラブルゴム（流動性のない生ゴム状のメチルビニルポリシロキサン）を用いた時（比較例３）と比較して、成形性に優れ、かつロールとしての性能も優れるものであった。
【図面の簡単な説明】
【図１】半導電ロールの電気特性を測定するために用いられた装置の概略図である。
【符号の説明】
１ ロール
２ 芯金
３ 電極
４ 抵抗値測定器[0001]
BACKGROUND OF THE INVENTION
The present invention provides a semiconductive region (10^Three-10^TenIt relates to a semiconductive roll exhibiting a stable electrical resistivity at Ω).
[0002]
[Prior art and problems to be solved by the invention]
Conventionally, 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^-1-10²Conductive rubber in the range of Ω · cm has been applied in a wide range of fields. On the other hand, silicone rubber, which is one of the electrically insulating rubbery substances, is excellent in heat resistance, cold resistance and weather resistance, and is widely used as an electrically insulating rubber, but it is conductive like other rubbery substances. It is also put into practical use as a conductive rubber by adding materials. Moreover, as a method for stabilizing the resistance value, addition of silicone powder is known as described in JP-A-3-195552.
[0003]
In this case, as the conductive material added to the conductive silicone rubber, for example, various metal powders such as carbon black, graphite, silver, nickel and copper, various nonconductive powders and the surface of short fibers are treated with a metal such as silver. The mixture of carbon fiber, metal fiber, and the like has a silicone rubber electrical resistivity of 10 depending on the type and amount of the conductive material without impairing the unique properties of silicone rubber.^Three-10^TenIt is frequently used because it can be reduced to about Ω · cm.
[0004]
However, when conductive carbon black such as ketjen black and acetylene black is blended with silicone rubber, 10^Three-10^TenIn the semiconducting region of Ω · cm, the variation in electric resistivity is extremely large, and it is difficult to stabilize the electric resistivity. This is thought to be due to the fact that the dispersion of carbon changes significantly depending on the molding conditions.
[0005]
  However, recently, in OA equipment parts, especially in dry copying machines.RugoAs a mu roll, the need for a semi-conductive roll is increased, and therefore, there is a demand for a semi-conductive roll exhibiting a stable electric resistivity with little variation in electric resistivity in the semi-conductive region.
[0006]
The present invention has been made in view of the above circumstances, and provides a semiconductive roll in which the variation in electric resistivity in the semiconductive region is extremely narrow and the electric resistivity is stable regardless of molding conditions. Objective.
[0007]
Means for Solving the Problem and Embodiment of the Invention
  As a result of intensive studies to achieve the above object, the present inventor has (A) in one molecule.,An alkenyl group bonded to a silicon atomIncluding at least 2YesAnd having an alkenyl group bonded to a silicon atom at the end of the molecular chain and having a linear structure represented by the following average composition formula (1)Liquid organopolysiloxane with specific viscosity, (B) One molecule has hydrogen atoms bonded to silicon atomsAnd expressed by the following average composition formula (2)Specific viscosity liquid organohydrogenpolysiloxane, (C) spherical silicone elastomer particles, (D) conductive materialAs one or more selected from acetylene black, conductive zinc white and conductive titanium oxide(E) The silicone rubber composition containing the addition reaction catalyst has low viscosity, excellent moldability, and does not cause troubles during molding such as deformation of a core metal such as an aluminum shaft, and the silicone rubber composition Is formed and cured to form a semiconductive cured product layer on the cored bar, whereby the cured product layer has an electrical resistance of 10 between the cored bar and the cured product layer surface.^Four-10⁸In a semi-conductive region of Ω, a stable electric resistivity with a variation of electric resistance of 2 digits or less is given, and in particular, a developing deviceFor charging roll, transfer roll or developing rollIt has been found that a highly stable semiconductive roll suitable for the above can be obtained, and the present invention has been made.
[0008]
  Accordingly, the present invention provides (A) one molecule,Containing at least two alkenyl groups bonded to the silicon atom,And having an alkenyl group bonded to the silicon atom at the end of the molecular chain,
The following average composition formula (1)
  R ¹ _a SiO _{(4-a) / 2} ... (1)
(Wherein R ¹ Are the same or different C1-C12 unsubstituted or substituted monovalent hydrocarbon groups. a is a positive number in the range of 1.5 to 2.8. )
Indicated by
Viscosity at 25 ° C100 ~100,000 mPa ·in sis thereLinear structureLiquid organopolysiloxane: 100 parts by weight
(B) containing at least three hydrogen atoms bonded to silicon atoms in one molecule;
The following average composition formula (2)
  R ² _b H _c SiO _{(4-bc) / 2} ... (2)
(Wherein R ² Is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms. b is 0.7 to 2.1, c is 0.001 to 1.0, and b + c is a positive number satisfying 0.8 to 3.0. )
Indicated by
Viscosity at 25 ° C0.11,000 mPa ·in sA certain liquid organohydrogenpolysiloxane: 0.1 to 30 parts by weight
(C) Spherical silicone elastomer particles having an average particle size of 0.1 to 100 μm: 5 to 200 parts by weight
(D)Acetylene as a conductive materialOne or more selected from black, conductive zinc white and conductive titanium oxideonly: 1 × 10 resistance between the cored bar and the cured product layer surface^Four~ 1x10⁸Ω amount
(E) Addition reaction catalyst: catalyst amount
A semiconductive cured product layer of a silicone rubber composition which is liquid at room temperature (25 ° C.) containingFor charging roll, transfer roll or developing roll in developing deviceA semiconductive roll is provided.
[0009]
  The present invention will be described in further detail below.
  The component (A) of the present invention is a liquid organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule. As this organopolysiloxane, one represented by the following average composition formula (1) is used.The
[0010]
R¹ _aSiO_{(4-a) / 2}         ... (1)
(Wherein R¹Are the same or different monovalent hydrocarbon groups having 1 to 12, preferably 1 to 8, carbon atoms. a is a positive number in the range of 1.5 to 2.8, preferably 1.8 to 2.5. )
[0011]
Where R¹As alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl, pentyl, neopentyl, hexyl, cyclohexyl, octyl, nonyl, decyl, etc. Aryl group such as phenyl group, tolyl group, xylyl group, naphthyl group, aralkyl group such as benzyl group, phenylethyl group, phenylpropyl group, vinyl group, allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group , Alkenyl groups such as cyclohexenyl group, octenyl group, etc., and those in which part or all of the hydrogen atoms of these groups are substituted with halogen atoms such as fluorine atom, bromine atom, chlorine atom, cyano group, etc., such as chloromethyl group Chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group, etc. Mentioned are but, all R¹It is preferable that 90% or more of is a methyl group.
[0012]
In addition, R¹At least two of them must be alkenyl groups (preferably those having 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, and particularly preferably vinyl groups).
[0013]
  The alkenyl group content is 1.0 × 10 6 in the organopolysiloxane.^-6~ 5.0 × 10^-3mol / g, especially 5.0 × 10^-6~ 1.0 × 10^-3It is preferable to set it as mol / g. The amount of alkenyl group is 1.0 × 10^-6If the amount is less than mol / g, crosslinking may be insufficient and a gel may be formed.^-3When the amount is more than mol / g, the crosslinking density becomes too high, and there is a fear that the rubber becomes brittle.
  This alkenyl group is bonded to the silicon atom at the end of the molecular chain.AndBonded to a silicon atom in the middle of the molecular chainMoyoYes.
[0014]
  The structure of the organopolysiloxane of the present invention basically has a main chain portion of R.¹ ₂SiO_2/2In which both ends of the molecular chain are R¹ _ThreeSiO_1/2Linear structure blocked with a triorganosiloxy group represented byIs.
  This organopolysiloxane is liquid at room temperature (25 ° C.) and its viscosity is 25 ° C.100 ~100,000 mPa ·s,Preferably, it is 100 to 50,000 mPa · s. If the viscosity is too high, stable electrical resistivity cannot be obtained in the semiconductive region.
[0015]
  The component (B) of the present invention is a liquid organohydrogenpolysiloxane containing at least three hydrogen atoms (Si—H groups) bonded to silicon atoms in one molecule, and the Si—H groups in the molecule (A) It crosslinks with the alkenyl group couple | bonded with the silicon atom in a component by hydrosilylation addition reaction, and acts as a hardening | curing agent for hardening a composition.
  As this organohydrogenpolysiloxane, one represented by the following average composition formula (2) is used.The
[0016]
R² _bH_cSiO_{(4-bc) / 2}         ... (2)
(Wherein R²Is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, preferably 1 to 8 carbon atoms. b is 0.7 to 2.1, c is 0.001 to 1.0, and b + c is a positive number satisfying 0.8 to 3.0. )
[0017]
Where R²As the monovalent hydrocarbon group, R¹Examples thereof are the same as those exemplified in the above, but those having no aliphatic unsaturated group (alkenyl group) are preferable, and a methyl group, a phenyl group, and a trifluoropropyl group are particularly preferable. B is preferably a positive number satisfying 0.8 to 2.0, c is preferably 0.01 to 1.0, and b + c is preferably a positive number satisfying 1.0 to 2.5.
[0018]
The organohydrogenpolysiloxane of the present invention has at least 3, preferably 3 to 100, more preferably 3 to 50, hydrogen atoms bonded to silicon atoms (Si—H group) in one molecule. is there.
[0019]
The Si—H group content in the organohydrogenpolysiloxane is preferably 0.001 to 0.017 mol / g, particularly preferably 0.002 to 0.015 mol / g. If the amount of Si-H groups is less than 0.001 mol / g, crosslinking may be insufficient and gelation may occur, and if it exceeds 0.017 mol / g, the crosslinking density becomes too high and brittle rubber There is a risk of becoming.
The hydrogen atom bonded to the silicon atom may be located at either the molecular chain end or in the middle of the molecular chain, or may be located at both.
[0020]
Examples of the organohydrogenpolysiloxane include trimethylsiloxy group-capped methylhydrogen polysiloxane at both ends, trimethylsiloxy group-capped dimethylsiloxane / methylhydrogensiloxane copolymer at both ends, dimethylhydrogensiloxy group-capped dimethylpolysiloxane at both ends, Both end dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer, Both end trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer, Both end trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane / Dimethylsiloxane copolymer (CH_Three)₂HSiO_1/2Unit and SiO_4/2A copolymer comprising units, (CH_Three)₂HSiO_1/2Unit and SiO_4/2Unit and (C₆H_Five)_ThreeSiO_3/2Examples thereof include a copolymer comprising units.
[0021]
  The molecular structure of the organohydrogenpolysiloxane may be any of linear, branched, cyclic, and three-dimensional network. The number of silicon atoms (polymerization degree) in one molecule is preferably 2 to 300, particularly about 4 to 150.
  Furthermore, this organohydrogenpolysiloxane is liquid at room temperature (25 ° C.), and its viscosity is 25 ° C.0.11,000 mPa ·s,Preferably it is 0.1-500 mPa * s.
[0022]
In addition, the compounding quantity of this organohydrogenpolysiloxane is 0.1-30 weight part with respect to 100 weight part of (A) component, Preferably it is 0.3-20 weight part.
Moreover, the compounding amount of this organohydrogenpolysiloxane is such that the amount of silicon atom-bonded hydrogen atoms (Si—H groups) in component (B) relative to alkenyl groups bonded to silicon atoms in component (A) is in molar ratio. In general, it can be blended in an amount of 0.3 to 10.0, preferably 0.5 to 5.0.
[0023]
As the spherical silicone elastomer particles of the component (C) of the present invention, those having an average particle size of 0.1 to 100 μm, preferably 0.5 to 40 μm are used. Particles having an average particle diameter of less than 0.1 μm are difficult to produce and the effect of adding them is difficult to obtain. If the average particle diameter exceeds 100 μm, the mechanical strength of the cured rubber is impaired. In addition, this average particle diameter can be calculated | required as a weight average value (or median diameter) etc. in the particle size distribution measurement by a laser beam diffraction method, for example.
[0024]
In this case, the spherical silicone elastomer particles are a cured product of an organopolysiloxane having the above average particle diameter (for example, a rubbery silicone elastic body (elastomer) cured product obtained by curing a curable organopolysiloxane composition by crosslinking). If it is, there is no restriction | limiting in the kind, grade, manufacturing method, etc., An appropriate thing can be used. The “spherical” in the component (C) means a substantially spherical granular material without corners, and does not necessarily mean a true spherical shape.
[0025]
Specifically, the spherical silicone elastomer particles are not particularly limited, but a method of obtaining a granular silicone elastomer by curing a curable organopolysiloxane composition in a spray dryer at 230 to 300 ° C. No. 59-96122), or a curable organopolysiloxane composition, for example, an addition-reaction type organopolysiloxane composition comprising a vinyl group-containing organopolysiloxane and an organohydrogenpolysiloxane with a surfactant in water. The emulsion particles are emulsified to a particle size of 20 μm or less, a platinum catalyst for addition reaction is added, and the organopolysiloxane contained in the emulsion particles is cured before spray drying or by the end of spray drying. Method (JP-A-62-2 Can be used, and in particular, a vinyl group-containing organopolysiloxane and an organohydrogenpolysiloxane are made into an emulsion using a surfactant and subjected to an addition reaction with a platinum-based catalyst and cured. What was manufactured in this way is preferable.
[0026]
As the elastomer particles, those whose surfaces have been treated with silane, siloxane or the like in advance or during the production thereof can also be used (for example, a silicone resin layer (that is, a three-dimensional surface on the surface of rubber-like silicone elastomer particles). Silicone rubber / resin composite particles having a network-like silicone resin layer)).
[0027]
The amount of the spherical silicone elastomer particles used is 5 to 200 parts by weight, preferably 10 to 150 parts by weight, based on 100 parts by weight of the organopolysiloxane of the component (A). When the blending amount of the spherical silicone elastomer particles is less than the above ratio, the effect of addition cannot be obtained, and when it exceeds the above ratio, the mechanical strength of the cured product decreases.
[0028]
  As the conductive material of the component (D) of the present invention,acetyleneOne or more of black, conductive zinc white, and conductive titanium oxide are used.
[0029]
  here,acetyleneAs black, those usually used in conductive rubber compositions are usually used.obtain.
[0030]
  In particular, ElectricAcetylene black (manufactured by Denki Kagaku Kogyo Co., Ltd.), Shaunigan acetylene black (manufactured by Shaunigan Chemical Co., Ltd.), etc.Is illustrated.
[0031]
  In additionACetylene black has a low impurity content and has a developed secondary structure structure, so it has excellent conductivity and is particularly preferably used in the present invention.The
[0032]
  The blending amount of the conductive material of the component (D) is the resistance between the surface of the cured product layer of the silicone rubber composition and the core metal on which the cured product layer is formed.1× 10^Four~ 1x10⁸This is the amount of Ω.
  Specifically, the aboveacetyleneThe amount of black added is preferably 0.5 to 50 parts by weight, particularly 1 to 20 parts by weight, based on 100 parts by weight of the organopolysiloxane of the component (A). If the amount added is less than 0.5 parts by weight, the desired conductivity may not be obtained. If the amount added exceeds 50 parts by weight, the electrical resistance between the surface of the obtained cured product layer and the cored bar is 10.^ThreeMay be less than Ω and may not be the intended semiconductive region.
[0033]
Further, as the conductive zinc white, specifically, conductive zinc white manufactured by Honjo Chemical Co., Ltd. is preferably used, preferably 30 to 300 parts by weight, more preferably 50 to 250 parts by weight. By adding, the volume resistivity of the cured product layer is 10^Three-10^TenΩ · cm, especially 10^Five-10^TenAn electrical resistance of Ω · cm can be obtained. If the addition amount is less than 30 parts by weight, conductivity may not be obtained. On the other hand, if it exceeds 300 parts by weight, the mechanical properties may be remarkably deteriorated. Therefore, the addition amount is 100 to 250 parts by weight. It is particularly preferred.
[0034]
Furthermore, as electroconductive titanium oxide, ET-500W (Ishihara Sangyo Co., Ltd. product) can be mentioned, for example. In this case, the basic composition is TiO₂・ SnO₂It is preferable to be doped with Sb. The addition amount is the same as the addition amount of the conductive zinc white described above.
[0035]
(E) Component addition reaction catalysts include platinum black, platinous chloride, chloroplatinic acid, a reaction product of chloroplatinic acid and a monohydric alcohol, a complex of chloroplatinic acid and an olefin, platinum bisacetoacetate, etc. Examples include platinum group metal catalysts such as platinum catalysts, palladium catalysts, rhodium catalysts. In addition, the compounding amount of this addition reaction catalyst is a catalyst amount, and it is preferable to mix | blend normally 0.5-1,000 ppm with respect to the sum total of (A) and (B) component as a metal component, especially about 1-500 ppm. .
[0036]
  The silicone rubber composition may contain reinforcing silica filler such as silica hydrogel (hydrous silicic acid), silica airgel (anhydrous silicic acid-fumed silica), clay, calcium carbonate, diatomaceous earth as necessary.SoilFillers, low molecular siloxane esters, silanols such as diphenylsilanediol,acidCeriumEtc.A heat resistance improver, various carbon functional silanes for improving adhesiveness and moldability, and halogen compounds for imparting flame retardancy may be added and mixed.
[0037]
The silicone rubber layer obtained by curing the liquid silicone rubber composition of the present invention usually has a volume resistivity of 1 × 10.^Three~ 1x10¹¹Ω · cm, preferably 1 × 10^Three~ 1x10^TenΩ · cm, more preferably 1 × 10^Four~ 1x10⁸Having a semiconductive region electrical resistance of about Ω · cm is desirable from the viewpoint of obtaining a semiconductive roll having a predetermined resistance between the core metal and the cured product layer surface.
[0038]
The liquid silicone rubber composition of the present invention has a viscosity at 25 ° C. of 100 to 100,000 poise (10 to 10,000 Pa · s), particularly 200 to 50,000 poise (20) from the viewpoint of moldability and workability. Is preferably in the range of ˜5,000 Pa · s). If it is less than 100 poise, the rubber elasticity and strength required as a semiconductive roll may not be obtained, and if the viscosity is too high, the composition has a high viscosity, which may cause molding troubles such as deformation of the core during molding. In addition, it is difficult to make the molding conditions constant, and a stable electrical resistivity cannot be obtained in the semiconductive region.
[0039]
The semiconductive roll of the present invention forms the semiconductive cured product layer (silicone rubber layer) of the silicone rubber composition on the core metal. In this case, the material, dimensions, etc. of the core metal are the types of rolls. Can be selected as appropriate. Also, the molding and curing method of the silicone rubber composition can be appropriately selected. For example, the silicone rubber composition can be molded by a method such as injection molding, transfer molding, injection molding or coating, and cured by heating.
[0040]
Moreover, the semiconductive roll of this invention may provide a fluororesin layer further in the outer periphery of a silicone rubber layer. In this case, the fluororesin layer is formed of a fluororesin coating material, a fluororesin tube, or the like, and covers the silicone rubber layer.
[0041]
Examples of the fluorine resin coating material include polytetrafluoroethylene resin (PTFE) latex and Daiel latex (produced by Daikin Industries, Ltd., fluorine latex). Moreover, as a fluorine resin tube, a commercial item can be used, for example, polytetrafluoroethylene resin (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), fluorinated ethylene-polypropylene copolymer. Resin (FEP), polyvinylidene fluoride resin (PVDF), polyvinyl fluoride resin and the like can be mentioned, among which PFA is particularly preferable.
[0042]
  The semiconductive cured product layer (silicone rubber layer) is usually formed to a thickness of 0.2 to 100 mm, particularly 0.5 to 50 mm, and the resistance between the surface and the core metal is low.1 × 10 ^Four ~ 1x10 ⁸ ΩIt is effective that the silicone rubber layer of the present invention has a variation in electric resistance within two digits within the range of the resistance value, so that the charging roll, transfer roll,OrDevelopment rowLeSuitable as a semiconductive layer.
[0043]
【The invention's effect】
The semiconductive roll of the present invention is stable in that the electrical resistivity in the semiconductive region is not affected by molding conditions and has extremely small variations and does not cause molding troubles such as deformation of the metal core during molding. Excellent in properties, vulcanization characteristics and rubber elasticity.
[0044]
【Example】
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. In the following examples, parts indicate parts by weight.
[0045]
[Example 1, Comparative Example 1]
100 parts of dimethylpolysiloxane (degree of polymerization 500) blocked at both ends with dimethylvinylsiloxy groups, specific surface area 110 m²/ G hydrophobized fumed silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) and spherical silicone elastomer particles KMP594 (particle diameter 3-10 μm, manufactured by Shin-Etsu Chemical Co., Ltd.), and acetylene black (Denka Black HS-100) , Manufactured by Denki Kagaku Kogyo Co., Ltd.) in an amount planetary mixer shown in Table 1, and after stirring for 30 minutes, methylhydrogenpolysiloxane having Si-H groups at both ends and side chains as a crosslinking agent. (Polymerization degree 17, Si-H group amount 0.0060 mol / g) 1.7 parts, ethynylcyclohexanol 0.05 part as a reaction control agent, platinum catalyst (Pt concentration 1%) 0.1 part, Stirring was continued for 15 minutes to obtain a silicone rubber composition.
[0046]
Next, primer No. 3 for addition reaction type liquid silicone rubber was applied to the surface of an aluminum shaft having a diameter of 10 mm and a length of 300 mm. 101A / B (manufactured by Shin-Etsu Chemical Co., Ltd.) is applied, the aluminum shaft is fixed in the mold, and the silicone rubber composition is placed in the mold at 10 kg / cm.²And cured by heating at 150 ° C. for 30 minutes and further post-cured at 180 ° C. for 2 hours to obtain a silicone rubber roll having a diameter of 20 mm. Troubles such as deformation of the aluminum shaft did not occur at the time of forming, and the surface accuracy of the obtained roll was sufficiently high and could be used as it is. Table 1 shows the results of measuring the hardness and electrical properties of this roll.
[0047]
As for electrical characteristics, the roll 1 was brought into contact with the electrode 3 having a width of 7 mm as shown in FIG. 1 and the resistance between the electrode 3 and the roll core 2 was measured. The measurement was performed 20 points in the axial direction, and the variation was evaluated. The measurement voltage was 100 V, and the resistance measuring instrument 4 was an Advantest Digital Ultra High Resistance Meter R8340.
[0048]
[Examples 2 and 3, Comparative Example 2]
100 parts of dimethylpolysiloxane (degree of polymerization 500) blocked at both ends with dimethylvinylsiloxy groups, specific surface area 110 m²/ G hydrophobized fumed silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) and spherical silicone elastomer particles KMP594 (particle diameter 3-10 μm, manufactured by Shin-Etsu Chemical Co., Ltd.), and conductive zinc white (Honjo Chemical ( Co., Ltd.) or white conductive titanium oxide ET-500W (Ishihara Sangyo Co., Ltd.) is placed in the amount planetary mixer shown in Table 1, and stirring is continued for 30 minutes. 1.7 parts of methyl hydrogen polysiloxane having a Si—H group (polymerization degree 17, Si—H group amount 0.0060 mol / g), 0.05 part of ethynylcyclohexanol as a reaction control agent, platinum catalyst (Pt 0.1 parts of a concentration of 1%) was added, and stirring was continued for 15 minutes to obtain a silicone rubber composition.
[0049]
Next, primer No. 3 for addition reaction type liquid silicone rubber was applied to the surface of an aluminum shaft having a diameter of 10 mm and a length of 300 mm. 101 A / B (manufactured by Shin-Etsu Chemical Co., Ltd.) was applied, and the silicone rubber composition was placed in a mold at a rate of 5 kg / cm between a 50 μm-thick PFA tube whose inner surface was primed and an aluminum shaft.²And cured by heating at 150 ° C. for 30 minutes and further post-cured at 180 ° C. for 2 hours to obtain a PFA resin-coated silicone rubber roll having an outer diameter of 20 mm × length of 250 mm. Troubles such as deformation of the aluminum shaft did not occur at the time of forming, and the surface accuracy of the obtained roll was sufficiently high and could be used as it is. Table 1 shows the results of measuring the hardness and electrical characteristics of this roll in the same manner as in Example 1.
[0050]
[Comparative Example 3]
100 parts of raw rubber-like methylvinylpolysiloxane having an average degree of polymerization of about 8,000 consisting of 99.85 mol% of dimethylsiloxane units and 0.15 mol% of methylvinylsiloxane units, and a specific surface area of 110 m²/ G hydrophobized fumed silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) and spherical silicone elastomer particles KMP594 (particle diameter 3-10 μm, manufactured by Shin-Etsu Chemical Co., Ltd.), and acetylene black (Denka Black HS-100) , Manufactured by Denki Kagaku Kogyo Co., Ltd.) in an amount planetary mixer shown in Table 1, and after stirring for 30 minutes, 2,5-dimethyl-2,5-di (t- Butylperoxy) hexane was added and stirring was continued for 15 minutes to obtain a silicone rubber composition.
[0051]
Next, on the surface of an aluminum shaft having a diameter of 10 mm and a length of 300 mm, a peroxide curable silicone rubber primer No. 18B (manufactured by Shin-Etsu Chemical Co., Ltd.) was applied, the aluminum shaft was fixed in the mold, and the silicone rubber composition was put in the mold at 80 kg / cm.²Filled with, heated and cured at 180 ° C. for 30 minutes, and further post cured at 180 ° C. for 2 hours to obtain a silicone rubber roll with a diameter of 20 mm, but the viscosity of the composition is high, and the trouble that the aluminum shaft deforms during molding often occurs did. Further, the roll obtained has low surface accuracy (rough surface), and the surface must be polished for actual use. Table 1 shows the results of measuring the hardness and electrical properties of the obtained rolls in the same manner as in Example 1.
[0052]
[Table 1]

From the results shown in Table 1, those containing spherical silicone elastomer particles (Examples 1 to 3) were more semiconductive than those not containing the elastomer particles and those containing a small amount (Comparative Examples 1 and 2). It showed a more stable electric resistance value, and it was confirmed that the variation was about one digit. Further, compared with the case where millable rubber (raw rubber-like methyl vinyl polysiloxane having no fluidity) was used (Comparative Example 3), the moldability was excellent and the performance as a roll was also excellent.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of an apparatus used to measure the electrical properties of a semiconductive roll.
[Explanation of symbols]
1 roll
2 Core
3 electrodes
4 Resistance measuring instrument

Claims (4)

(A) in one molecule, the alkenyl group bonded to a silicon atom at least two containing and having alkenyl groups bonded to the silicon atoms at the molecular chain terminals,
The following average composition formula (1)
R ¹ _a SiO _{(4-a) / 2} (1)
(In the formula, R ¹ is the same or different, unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms. A is a positive number in the range of 1.5 to 2.8.)
Indicated by
Liquid organopolysiloxane having a linear structure having a viscosity at 25 ° C. of 100 to 100,000 mPa · s : 100 parts by weight (B) One molecule contains at least three hydrogen atoms bonded to silicon atoms,
The following average composition formula (2)
R ² _b H _c SiO _{(4-bc) / 2} (2)
Wherein R ² is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 12 carbon atoms, b is 0.7 to 2.1, c is 0.001 to 1.0, and b + c Is a positive number satisfying 0.8 to 3.0.)
Indicated by
Liquid organohydrogenpolysiloxane having a viscosity at 25 ° C. of 0.1 to 1,000 mPa · s : 0.1 to 30 parts by weight (C) Spherical silicone elastomer particles having an average particle size of 0.1 to 100 μm: 5 ~ 200 parts by weight (D) As the conductive material, only one or two or more selected from acetylene black, conductive zinc white and conductive titanium oxide: resistance between the cored bar and the cured layer surface is 1 × Amount of 10 ⁴ to 1 × 10 ⁸ Ω (E) addition reaction catalyst: characterized in that a semiconductive cured product layer of a silicone rubber composition which is liquid at room temperature containing a catalytic amount is formed on a cored bar. A semiconductive roll for a charging roll, a transfer roll or a developing roll in the developing device . The semiconductive roll according to claim 1, wherein the conductive material is acetylene black. The semiconductive roll according to claim 1 or 2 , wherein the spherical silicone elastomer particles as the component (C) have an average particle size of 0.5 to 40 µm. The semiconductive roll according to any one of claims 1 to 3 , wherein a fluororesin layer is further provided on the outer periphery of the semiconductive cured product layer.

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