JP2003082232A - Silicone rubber composition for semiconductive roller and semiconductive roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductive roller which has volume resistivity in a semiconductive range not affected by molding conditions, having extremely slight dispersion and being stable, provides stable electric properties even under environmental conditions of a wide range of temperature, humidity, etc., and has excellent molding processability, vulcanization properties and rubber elasticity. SOLUTION: This silicone rubber composition for semiconductive roller is obtained by mixing 100 parts.wt. of a thermosetting organopolysiloxane composition with 0.001-10 parts.wt. of a lithium salt.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a semiconductive roller which has a volume resistivity in a semiconductive region (1 × 10 ³ to 1 × 10 ¹⁰ Ω · cm) and provides a semiconductive roller exhibiting a stable volume resistivity. The present invention relates to a silicone rubber composition for rollers and a semiconductive roller using the same.

[0002]

2. Description of the Related Art Conventionally, various rubber materials have been known in which a conductive material is added to a rubber-like substance having an electric insulation property to impart conductivity, and, for example, a conductive material is known. A conductive rubber having a volume resistivity in the range of 1 × 10 ⁻¹ to 1 × 10 ² Ω · cm mixed with carbon black or the like has been applied in a wide field.

On the other hand, silicone rubber, which is one of the electrically insulating rubber-like substances, is excellent in heat resistance, cold resistance and weather resistance and is widely used as an electrically insulating rubber. Similarly, by adding a conductive material, it has been put to practical use as a conductive rubber. As a method for stabilizing the volume resistivity, addition of silicone powder is known as described in JP-A-3-195752.

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 non-conductive powders and short fiber surfaces such as silver. The one treated with metal, the one mixed with carbon fiber, metal fiber, etc., has an electrical resistivity of silicone rubber of 1 × 10 ⁻³ depending on the kind and filling amount of the conductive material without impairing the unique properties of rubber. ~ 1
It is often used because it can be lowered to about 10 ¹⁰ Ω · cm.

However, when synthetic carbon such as silicone rubber is mixed with conductive carbon such as Ketjen black or acetylene black, 1 × 10 ³ to 1 × 10 ¹⁰ Ω
In the semi-conductive region of cm, the variation in volume resistivity was extremely large, and it was very difficult to stabilize it. It is considered that this is because the dispersion of the conductive carbon significantly changes depending on the molding conditions.

Further, Japanese Patent Application Laid-Open No. 2001-164118 proposes a semiconductive silicone rubber composition in which a conductive titanium oxide whisker and an antistatic agent having a portion containing a metal ion in the molecule are used in combination. It was insufficient to solve the above problems.

However, recently, parts of OA equipment, especially a charging roller, a developing roller, and the like in a dry copying machine,
Paper feed roller, fixing roller, pressure roller, static elimination roller,
As a rubber roller such as a cleaning roller and an oil applying roller, the need for a semi-conductive roller is increasing, and therefore, there is a demand for a semi-conductive roller that exhibits a small volume resistivity variation in a semi-conductive region and exhibits a stable volume resistivity.

The present invention has been made in view of the above circumstances, and the fluctuation range of the volume resistivity in the semiconductive region is extremely narrow,
An object of the present invention is to provide a semiconductive roller whose volume resistivity is stable regardless of molding conditions.

[0009]

Means for Solving the Problems and Modes for Carrying Out the Invention As a result of intensive studies to achieve the above object, the present inventor has blended a thermosetting organopolysiloxane composition with a specific amount of a lithium salt. When a silicone rubber composition is used and molded and cured to form a silicone rubber cured product layer on a core metal, the rubber cured product layer has a size of 1 × 10 ³ to 1 × 10.
The volume resistivity variation in the semi-conductive region of ¹⁰ Ω · cm gives a stable volume resistivity of 2 digits or less, and
The inventors have found that a highly stable semiconductive roller which gives stable electric characteristics even under a wide range of environmental conditions such as temperature and humidity and which is particularly suitable for a developing device has been completed, and thus has accomplished the present invention.

Therefore, in the present invention, 100 parts by weight of the thermosetting organopolysiloxane composition is added to 0.001 of the lithium salt.
Provided is a silicone rubber composition for a semiconductive roller characterized by containing 10 to 10 parts by weight, and a semiconductive roller characterized by comprising a cured metal layer of the composition formed on a core metal.

The present invention will be described in more detail below. The silicone rubber composition of the present invention is a thermosetting organopolysiloxane composition blended with a lithium salt.

The above-mentioned thermosetting organopolysiloxane composition does not contain a lithium salt and is not particularly limited as long as it is an organopolysiloxane composition which is cured by heat, but it contains a conductive material. It is preferable. More specifically, for example, (A) an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule, (B) at least three hydrogen atoms bonded to silicon atoms in one molecule. Organohydrogenpolysiloxane to be contained, (C) a conductive material other than a lithium salt, and (D) a hydrosilylation reaction catalyst, or the above (A) component, (C) component and (E)
Those containing an organic peroxide are preferably used.

As the organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule of component (A), those represented by the following average composition formula (1) can be used. R ¹ _a SiO _{(4-a) / 2} (1) (In the formula, R ^{1 s} are the same or different and have 1 to 12 carbon atoms;
It is preferably a 1-8 unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number in the range of 1.5-2.8, preferably 1.9-2.5. )

Here, the unsubstituted or substituted monovalent hydrocarbon group represented by R ¹ is a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group or te.
rt-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, dodecyl group and other alkyl groups, phenyl group, tolyl group, xylyl group, naphthyl group and other aryl groups, benzyl Groups, aralkyl groups such as phenethyl groups, vinyl groups, allyl groups, propenyl groups, isopropenyl groups, butenyl groups, hexenyl groups, cyclohexenyl groups, alkenyl groups such as octenyl groups, and some of the hydrogen atoms of these groups or All of them are substituted with halogen atoms such as fluorine atom, bromine atom and chlorine atom, cyano group and the like, for example, chloromethyl group, chloropropyl group, bromoethyl group, trifluoropropyl group, cyanoethyl group, etc. 90% of ¹
The above is preferably a methyl group. Further, at least two of R ¹ need to be alkenyl groups (preferably having 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, and particularly preferably vinyl group).

The content of the alkenyl group is 1.0 × 10 ^{−6 to} 5.0 × 10 ⁻³ mo in the organopolysiloxane.
1 / g, especially 5.0 × 10 ^{−6 to} 1.0 × 10 ⁻³ mol /
It is preferably g. The amount of alkenyl groups is 1.0 x
If it is less than 10 ^-6 mol / g, crosslinking may be insufficient and gelation may occur, and 5.0 × 10 ^-3 mol / g
If it is more than g, the crosslink density becomes too high, which may result in brittle rubber. The alkenyl group may be bonded to a silicon atom at the end of the molecular chain, a silicon atom in the middle of the molecular chain, or both.

The structure of this organopolysiloxane is basically composed of repeating diorganosiloxane units represented by R ¹ ₂ SiO _2/2 in the main chain portion, and both ends of the molecular chain are R groups.
It is preferable to have a linear structure blocked with a triorganosiloxy group represented by ¹ ₃ SiO _1/2 , but it may have a partially branched structure, a cyclic structure, or the like, and particularly in terms of molecular weight. The viscosity is not limited and may be liquid at room temperature (25 ° C) or raw rubber as long as the viscosity is 10 mPa · s or more, but it is liquid at room temperature and has a viscosity of 25 ° C.
At 100,000 mPa · s or less, especially 100 to 50,
It is preferably 000 mPa · s.

The organohydrogenpolysiloxane containing at least three hydrogen atoms (Si—H groups) bonded to silicon atoms in one molecule of the component (B) is represented by the following average composition formula (2). It can be used, but this is one in which the Si-H group in the molecule acts as a curing agent for curing the composition by hydrosilyl addition reaction with the alkenyl group bonded to the silicon atom in the component (A). is there.

R ² _b H _c SiO _{(4-bc) / 2} (2) (In the formula, R ^{2 s} are the same or different and have 1 to 12 carbon atoms;
It is preferably an unsubstituted or substituted monovalent hydrocarbon group having 1 to 8 carbon atoms, b is 0.7 to 2.1, and c is 0.001 to 1.
0 and b + c are positive numbers satisfying 0.8 to 3.0. )

[0019] As the monovalent hydrocarbon group represented by R ^2, there may be mentioned the same ones as exemplified for R ^1, it is having no aliphatic unsaturated group (alkenyl group) Preferably, b is preferably 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.

The above organohydrogenpolysiloxane contains at least 3, preferably 3 to 100, and more preferably 3 to 50 Si-H groups in one molecule.

The content of this Si--H group is 0.001 to 0.017 m in the organohydrogenpolysiloxane.
It is preferable to set it as ol / g, especially 0.002-0.015 mol / g. The amount of Si-H group is 0.001 mol
If it is less than 0.1 g / g, crosslinking may be insufficient and a gel may be formed. If it is more than 0.017 mol / g, the crosslinking density may be too high and brittle rubber may be obtained. The hydrogen atom bonded to the silicon atom may be located at the end of the molecular chain or in the middle of the molecular chain,
It may be located in both.

Examples of the organohydrogenpolysiloxane include trimethylsiloxy group-blocked methylhydrogenpolysiloxane at both ends, trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer at both terminals, and dimethylhydrogensiloxy group-blocked dimethyl at both terminals. Polysiloxane, dimethylhydrogensiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer at both ends, trimethylsiloxy group-blocked methylhydrogensiloxane / diphenylsiloxane copolymer at both ends, trimethylsiloxy group-blocked methylhydrogensiloxane at both ends Diphenyl siloxane / dimethyl siloxane copolymer, (CH ₃ ) ₂
A copolymer consisting of HSiO _1/2 units and SiO _4/2 units,
(CH ₃ ) ₂ HSiO _1/2 unit, SiO _4/2 unit and (C
₆ H ₅ ) SiO _3/2 units and the like.

The molecular structure of the organohydrogenpolysiloxane may be linear, cyclic, branched or three-dimensional network structure, and the number of silicon atoms in one molecule (degree of polymerization). 3 to 300 pieces, particularly 4 to 150 pieces, which are liquid at room temperature (25 ° C.) are preferably used, and the viscosity thereof at 25 ° C. is preferably 1,000 mPa · s or less, more preferably 0. It is 1 to 500 mPa · s.

The amount of the organohydrogenpolysiloxane blended is preferably 0.1 to 30 parts by weight, more preferably 0.3 to 20 parts by weight, based on 100 parts by weight of the component (A). The amount of the organohydrogenpolysiloxane blended is such that the amount of hydrogen atoms (Si—H groups) bonded to the silicon atom in the component (B) is molar relative to the alkenyl group bonded to the silicon atom in the component (A). It can also be blended in an amount of usually 0.3 to 10.0, preferably 0.5 to 5.0.

The conductive material other than the lithium salt as the component (C) is not particularly limited as long as it has conductivity, but conductive carbon black, conductive zinc white, conductive titanium oxide, etc. Of these, it is preferable to contain one kind or two or more kinds.

As the conductive carbon black, those which are commonly used in conductive rubber compositions can be used. For example, acetylene black, conductive furnace black (CF), super conductive furnace black (SCF), extra conductive furnace black ( XCF), conductive channel black (CC), furnace black heat-treated at a high temperature of about 1,500 ° C., channel black, and the like.

Specifically, as acetylene black, Denka acetylene black (manufactured by Denki Kagaku), Shaunigan acetylene black (manufactured by Shawnigan Chemical)
As a conductive furnace black, Continex CF (manufactured by Continental Carbon Co., Ltd.), Vulcan C (manufactured by Cabot Co.), etc. are used as super conductive furnace blacks, and Continex SCP.
(Continental Carbon Co., Ltd.), Vulcan SC (Cabot Co.), etc., as Extra Conductive Furnace Black, Asahi HS-500 (Asahi Carbon Co., Ltd.), Vulcan XC-72 (Cabot Co., Ltd.), etc. as Conductive Channel Black. Is Kolux L
(Manufactured by Degussa) and the like, and Ketjen Black EC and Ketjen Black EC-600JD (manufactured by Ketjen Black International), which are types of furnace black, can also be used.

Among these, acetylene black is excellent in conductivity because it has a low impurity content and has a developed secondary structure structure, and is particularly preferably used in the present invention. In addition, Ketjen Black EC, Ketjen Black EC-600JD and the like, which have excellent conductivity even with a low filling amount due to their excellent specific surface area, can be preferably used.

The compounding amount of the conductive material other than the lithium salt is
The cured product of the thermosetting organopolysiloxane composition has a volume resistivity of 1 × 10 ³ to 1 × 10 ¹⁰ Ω · cm, particularly 1 × 1.
The amount is 0 ⁴ to 1 × 10 ⁸ Ω · cm, but when the conductive carbon black is used as the conductive material, the addition amount is 0.5 to 100 parts by weight of the component (A) described above.
It is preferably 50 parts by weight, particularly preferably 1 to 20 parts by weight. If the addition amount is less than 0.5 parts by weight, the desired conductivity may not be obtained, and if it exceeds 50 parts by weight, the volume resistivity of the obtained cured product may be less than 1 × 10 ³ Ω · cm. Therefore, the desired semiconductive region may not be obtained.

Further, as the electroconductive zinc white, specifically, electroconductive zinc white manufactured by Honjo Chemical Co., Ltd. is preferably used, and it is 3 per 100 parts by weight of the above-mentioned component (A).
It is preferable to add 0 to 300 parts by weight, particularly 50 to 250 parts by weight, whereby 1 × 10 ⁶ to 1 × 10 ¹⁰ Ω ·
A volume resistivity of cm can be obtained. If the amount added is less than 30 parts by weight, conductivity may not be obtained, while if it exceeds 300 parts by weight, mechanical properties may be significantly deteriorated.
More preferably, it is 0 part by weight.

Further, the conductive titanium oxide may be in the form of powder or needles, and examples thereof include ET-500W (manufactured by Ishihara Sangyo Co., Ltd.). In this case, the basic composition is Ti
It is preferable that Sb is doped into O ₂ .SnO ₂ . The added amount is the same as the above-mentioned added amount of conductive zinc white.

Examples of the hydrosilylation reaction catalyst of the component (D) include platinum black, chloroplatinic acid, chloroplatinic acid, a reaction product of chloroplatinic acid and a monohydric alcohol, a complex of chloroplatinic acid and olefins, and platinum. Examples thereof include bisacetoacetate, palladium-based catalysts and rhodium-based catalysts. The amount of the hydrosilylation reaction catalyst to be added is a catalytic amount and can be appropriately selected. However, it is usually 0.5 to 1,000 ppm, particularly preferably 0.5 to 1,000 ppm as the metal content based on the total of the components (A) and (B). It is preferable to add about 1 to 500 ppm.

The organic peroxide as the component (E) is used as a catalyst for accelerating the crosslinking reaction of the component (A) and may be a conventionally known one, for example, benzoyl peroxide, 2, 4-dichlorobenzoyl peroxide, p-methylbenzoyl peroxide, o-methylbenzoyl peroxide, 2,4-dicumyl peroxide, 2,5-dimethyl-bis (2,5- (ter
t-butyl) peroxy) hexane, di-tert-butylperoxide, tert-butylperbenzoate, 1,1-bis (tert-butylperoxycarboxy) hexane and the like, but not limited thereto. . The addition amount may be appropriately selected according to the curing speed, but is usually in the range of 0.1 to 10 parts by weight, particularly 0.2 to 2 parts by weight, relative to 100 parts by weight of the component (A). It is preferable.

Further, in the above thermosetting organopolysiloxane composition, if necessary, reinforcing silica filler such as silica hydrogel (hydrous silicic acid), silica aerogel (silicic anhydride-fumed silica), clay, calcium carbonate. , Diatomaceous earth, fillers such as titanium dioxide, low-molecular-weight siloxane esters, silanols, dispersants such as diphenylsilanediol, heat resistance improvers such as iron oxide, cerium oxide, iron octylate, adhesion and molding processability. Various carbon functional silanes for improving and halogen compounds for imparting flame retardancy may be added and mixed.

In the present invention, the lithium salt is a salt in which a lithium positive ion and an arbitrary monovalent negative ion are ionically bonded, and these may be used as the lithium salt alone, or the lithium salt may be used as an organic solvent or a liquid organic solvent. It may be used as a solution dissolved in a molecule.

The lithium salt is not limited at all
Are used in so-called lithium ion conductive agents.
A thium salt is preferably used. As an example, Li
BF _Four, LiClO_Four, LiPF₆, LiAsF₆, LiS
bF₆, LiSO₃CF₃, LiN (SO₂CF₃)₂, Li
SO₃C_FourF₉, LiC (SO₂CF₃)₃, LiB (C
₆H_Five)_FourEtc., but the ion radius is very small.
The ionic radius of monovalent negative ions is
Large LiN (SO₂CF₃)₂, LiC (SO₂CF ₃)₃
Is preferred. In addition, LiCl is inexpensive and easily available
O_FourIs also preferably used.

When the lithium salt is used as a solution, the organic solvent for dissolving the lithium salt is preferably a polar solvent having a high solubility for the lithium salt, and examples thereof include methanol, ethanol, n-propyl alcohol, isopropyl alcohol, Alcohols such as n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, amyl alcohol and hexyl alcohol, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, diethyl ether, dibutyl ether, tetrahydrofuran and 1,4-dioxane. And the like, and diethyl carbonate, dipropyl carbonate, ethylene carbonate, propylene carbonate, and other carbonates. In the ester system, acetic acid esters such as ethyl acetate, n-propyl acetate and isobutyl acetate, malonic acid esters,
Succinates, glutarates, adipates, phthalates and the like are also preferable. In particular, as a substituent of these organic solvents, an alkylene oxide group, preferably an ethylene oxide group (—CH ₂ C
Those containing H ₂ O-) are relatively preferable because they have a relatively high polarity and the solubility of the lithium salt is high.

On the other hand, as the liquid organic polymer in which the lithium salt is dissolved, if the organic polymer itself is a liquid having a relatively low molecular weight, it may be used as it is, or a liquid or solid organic polymer may be used as the organic polymer. You may use it as a solution which melt | dissolved in the monomer which comprises a molecule | numerator, or an organic solvent.

Examples of the above-mentioned organic polymer are not particularly limited as long as they are obtained by polymerizing, condensing and polycondensing a monomer, and polyester, polyether, polyurethane, polycarbonate, polyamide, polyimide, poly (meth) acrylate. , Polyphosphazene, polyvinyl alcohol and the like.

As the organic solvent for dissolving the organic polymer,
Aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as n-hexane, ligroin, kerosene and mineral spirits, alicyclic hydrocarbons such as cyclohexane and decahydronaphthalene, methanol, ethanol, n
-Propyl alcohol, isopropyl alcohol, n-
Butyl alcohol, isobutyl alcohol, tert-
Butyl alcohol, amyl alcohol, hexyl alcohol and other alcohols, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and other ketones, diethyl ether, dibutyl ether, tetrahydrofuran, 1,4-dioxane and other ethers, diethyl carbonate, dipropyl Carbonates such as carbonate, ethylene carbonate, propylene carbonate, acetic acid esters such as ethyl acetate, n-propyl acetate, isobutyl acetate, malonic acid esters, succinic acid esters, glutaric acid esters, adipic acid esters, phthalates Examples include ester-based solvents such as acid esters.

On the other hand, when the organic polymer is dissolved with the monomer constituting the organic polymer, it is preferable to use the monomer constituting the polymer to be dissolved, such as ethylene glycol, diethylene glycol, 1 , 4-butanediol, 1,6-hexanediol, catechol and other alcohols, ethylenediamine, hexamethylenediamine, isophoronediamine and other amines, adipic acid,
Carboxylic acids such as phthalic acid, hexamethylene diisocyanate, isocyanates such as isophorone diisocyanate, ethylene oxide, propylene oxide,
Alkylene oxides such as tetrahydrofuran, alkylene carbonates such as ethylene carbonate and propylene carbonate, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth ) (Meth) acrylates such as acrylate, N-vinylpyrrolidone, γ-caprolactone, ε-caprolactam, vinyl acetate and the like are exemplified.

In order to improve the solubility of the lithium salt, the liquid organic polymer has an alkylene oxide group, preferably an alkylene oxide group, as a substituent, in any or all of the organic polymers, organic solvents and monomers constituting the liquid organic polymer. It is preferable that an ethylene oxide group (—CH ₂ CH ₂ O—) is contained.

The amount of the lithium salt added is 0.001 to 10 parts by weight, preferably 0.01 to 1 part by weight, relative to 100 parts by weight of the above-mentioned thermosetting organopolysiloxane composition.
The amount may be in the range of 0.1 part by weight, more preferably 0.1 to 0.5 part by weight. If it is less than 0.001 part by weight, the lithium ion concentration is too low and the ionic conductivity is insufficient. If it exceeds 10 parts by weight, the lithium salt absorbs water in the air and deliquesces, resulting in insufficient ionic conductivity. .

In addition to the above-mentioned essential components, a reinforcing silica powder may be added as an optional component to the silicone rubber composition according to the present invention as long as it does not impair the effects of the present invention. The reinforcing silica powder is added to obtain a silicone rubber having excellent mechanical strength. For this purpose, the specific surface area is 50 m ² / g or more, preferably 100 to 300 m ² / g. Is. If the specific surface area is less than 50 m ² / g, the mechanical strength of the cured product will be low. As such a reinforcing silica,
For example, fumed silica, precipitated silica and the like can be mentioned, and those whose surface is made hydrophobic with chlorosilane or hexamethyldisilazane are also suitably used.

The amount of the reinforcing silica powder added is 0 to 5 with respect to 100 parts by weight of the organopolysiloxane as the component (A).
0 parts by weight, particularly preferably 1 to 20 parts by weight,
If it exceeds 50 parts by weight, the workability may deteriorate and the mechanical strength may decrease.

Silicone rubber powder, red iron oxide,
Fillers such as crushed quartz and calcium carbonate may be added.

Furthermore, in the case of molding a sponge, an inorganic material,
Add an organic blowing agent. Examples of the foaming agent include azobisisobutyronitrile, dinitropentamethylenetetramine, benzenesulfone hydrazide azodicarbonamide, and the addition amount thereof is 1 to 10 parts by weight based on 100 parts by weight of the silicone rubber composition. Ranges are preferred. Thus, by adding a foaming agent to the silicone rubber composition of the present invention, a sponge-like silicone rubber can be obtained.

If necessary, various additives such as a colorant and a heat resistance improver, a reaction control agent, a release agent or a filler dispersant are added to the silicone rubber composition of the present invention. Although it is optional, diphenylsilanediol, various alkoxysilanes, carbon functional silanes, silanol group-containing low molecular weight siloxanes and the like used as the filler dispersant are the minimum so as not to impair the effects of the present invention. It is preferable to limit the amount added.

Further, in order to make the silicone rubber composition of the present invention flame-retardant and fire-resistant, a platinum-containing material, a platinum compound and titanium dioxide, platinum and manganese carbonate, platinum and γ-Fe.
Known additives such as ₂ O ₃ , ferrite, mica, glass fiber and glass flakes may be added.

In the silicone rubber composition according to the present invention, the above-mentioned components are uniformly mixed using a rubber kneader such as a two-roll, Banbury mixer, dough mixer (kneader) or the like, and heat-treated if necessary. It can be obtained by applying.

The semiconductive roller of the present invention is one in which a semiconductive cured material layer of the above silicone rubber composition is formed on a core metal. In this case, the material and size of the core metal depend on the type of roller. It can be selected as appropriate.

The method of molding and curing the silicone rubber composition can be appropriately selected. For example, injection molding, transfer molding, injection molding, coating and the like can be used for molding, and the molded composition can be cured by heating. A fluororesin layer or a urethane resin layer may be further provided on the outer circumference of the silicone rubber layer, and the outer circumference resin layer is formed by a resin coating material, a resin tube or the like.

Examples of the fluororesin coating material for coating the silicone rubber layer include polytetrafluoroethylene resin (PTFE) latex, Daier latex (fluorine latex manufactured by Daikin Industries, Ltd.) and the like. As the resin tube, a commercially available product can be used. For example, polytetrafluoroethylene resin (PTFE), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin (PF
A), fluorinated ethylene / polypropylene copolymer resin (FEP), polyvinylidene fluoride resin (PVDF),
Polyvinyl fluoride resin and the like can be mentioned, but among these, PFA is preferable.

On the other hand, examples of the urethane resin coating material include dialomer (manufactured by Dainichiseika Kogyo Co., Ltd.) and die plastic coat (manufactured by Dainichiseika Kogyo Co., Ltd.), and urethane resin tubes such as tofretane (manufactured by Nippon Bulker Co., Ltd.) Can be mentioned.

The semiconductive cured material layer usually has a thickness of 0.
It is molded to a thickness of 2 to 50 mm, especially 0.5 to 30 mm, and its volume resistivity is 1 × 10 ³ to 1 × 10 ¹⁰ Ω · cm.
It is effective that the semiconductive cured material layer has a variation in volume resistivity within two digits within the above range.
It is suitable as a semiconductive layer such as a paper feed roller. Further, even if the semiconductive cured material layer is exposed to a wide range of temperature and humidity conditions for a long time, the change in volume resistivity due to the environment is within two digits, which is suitable as a semiconductive layer.

[0056]

EFFECTS OF THE INVENTION The semiconductive roller of the present invention has a volume resistivity in the semiconductive region which is not affected by molding conditions, has little variation and is stable, and has a wide range of environmental conditions such as temperature and humidity. But it gives stable electrical characteristics,
It is also excellent in moldability, vulcanization characteristics and rubber elasticity.

[0057]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1] 100 parts by weight of dimethylpolysiloxane (polysiloxane A, degree of polymerization: 500) having both ends blocked with dimethylvinylsiloxy groups, and a specific surface area of 1
5 parts by weight of fumed silica (R-972, manufactured by Nippon Aerosil Co., Ltd.) having a hydrophobicity of 10 m ² / g and 3 parts by weight of acetylene black (Denka Black HS-100, manufactured by Denki Kagaku Co., Ltd.) are planetary mixers. Charge to
After continuing stirring for 30 minutes, methyl hydrogen polysiloxane having a Si—H group at both ends and side chains as a cross-linking agent (polysiloxane B, degree of polymerization 17, Si—H amount of 0.
1.7 parts by weight, ethynylcyclohexanol as a reaction control agent 0.05 parts by weight, platinum catalyst (Pt concentration 1%) 0.5 parts by weight, lithium perchlorate powder 0.1 parts by weight as a lithium salt. Was added and stirring was continued for another 15 minutes to obtain a silicone rubber composition.

Next, on the surface of an aluminum shaft having a diameter of 10 mm and a length of 300 mm, a hydrosilylation reaction type liquid silicone rubber primer No. 101A / B (manufactured by Shin-Etsu Chemical Co., Ltd.) was applied. The aluminum shaft was fixed in a mold, the silicone rubber composition was filled in the mold at 10 kg / cm ² , heat-cured at 150 ° C. for 30 minutes, and post-cured at 180 ° C. for 2 hours to obtain an outer diameter. Three
A silicone rubber roller having a length of 0 mm and a length of 250 mm was prepared, and the hardness and the initial volume resistivity of the obtained roller were measured. Further, in order to evaluate the environmental dependence, the volume resistivity after the environmental test in which the sample was stored for 1 week under the condition of temperature 70 ° C./humidity 80% was also measured. The results are shown in Table 1.

The volume resistivity was measured by bringing the roller 1 into contact with an electrode 3 having a width of 7 mm as shown in FIG. 1 and applying a measuring voltage of 100 V between the electrode 3 and the roller core metal 2. At the measurement point, slide the terminal 4 in the axial direction to
The variation was evaluated in terms of points. As the measuring device 5, a digital wave ultra high resistance meter R8340 manufactured by Advantest was used.

Example 2 Example 1 was repeated except that 0.5 parts by weight of lithium perchlorate powder was replaced by 5 parts by weight of a 10 wt% butoxyethoxyethyl acetate solution of lithium perchlorate as the lithium salt. A silicone rubber composition was obtained in the same manner as. Next, a silicone rubber roller was prepared in the same manner as in Example 1, and the hardness and electric characteristics of the obtained roller were measured. The results are shown in Table 1.

[Example 3] As a lithium salt, 0.5 parts by weight of lithium perchlorate powder was replaced with 10% by weight of lithium perchlorate of polyethylene glycol (PEG) 400.
As in Example 1, except that 5 parts by weight of the solution was used,
A silicone rubber composition was obtained. Next, a silicone rubber roller was prepared in the same manner as in Example 1, and the hardness and electric characteristics of the obtained roller were measured. The results are shown in Table 1.

Example 4 Dimethylsiloxane Unit 9
9.85 mol% and methyl vinyl siloxane unit 0.1
Hydrophobized fumed sinker (R-972, Japan, 100 parts by weight of methyl vinyl polysiloxane (polysiloxane C) having an average degree of polymerization of 5 mol% and a specific surface area of 110 m ² / g) 8 parts by weight of Aerosil, acetylene black (Denka Black H)
S-100, manufactured by Denki Kagaku Kogyo Co., Ltd.) and 4 parts by weight of lithium perchlorate powder as a lithium salt were added and kneaded. Then, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexane was added as an organic peroxide and kneaded to obtain a silicone rubber composition.

Then, the surface of an aluminum shaft having a diameter of 10 mm and a length of 300 mm was coated with a peroxide-curable silicone rubber primer No. 18B (manufactured by Shin-Etsu Chemical Co., Ltd.) was applied. The aluminum shaft was fixed in a mold, and the silicone rubber composition was put in the mold at 80 kg / c.
m ² filled, heat cured at 180 ° C. for 30 minutes, then 1
Post cure at 80 ° C for 2 hours, outside diameter 30mm x length 2
A 50 mm silicone rubber roller was prepared, and the hardness and electric characteristics of the obtained roller were measured in the same manner as in Example 1.
The results are shown in Table 1.

Comparative Example 1 A silicone rubber composition was obtained in the same manner as in Example 1 except that the lithium salt was not added. Next, a silicone rubber roller was prepared in the same manner as in Example 1, and the hardness and electric characteristics of the obtained roller were measured. The results are shown in Table 1.

Comparative Example 2 A silicone rubber composition was obtained in the same manner as in Example 4 except that the lithium salt was not added. Next, a silicone rubber roller was prepared in the same manner as in Example 4, and the hardness and electric characteristics of the obtained roller were measured. The results are shown in Table 1.

[0067]

[Table 1]

[Brief description of drawings]

FIG. 1 is a schematic diagram of an apparatus used to measure volume resistivity.

[Explanation of symbols]

1 roller 2 Roller core 3 electrodes 4 terminals 5 Measuring equipment

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsutomu Nakamura             Gunma Prefecture Usui District, Matsuida Town             Shin-Etsu Chemical Co., Ltd. Silicone electronic materials             Inside the technical laboratory F term (reference) 3J103 AA13 FA02 FA14 GA57 HA20                       HA31 HA47 HA52 HA53                 4J002 CP031 DA017 DA037 DA077                       DA087 DB006 DE107 DE137                       DG046 DH006 DK006 FD01                       FD06 FD13 FD14 FD32 GM00

Claims (8)

[Claims] 1. A silicone rubber composition for a semiconductive roller, which comprises 100 parts by weight of a thermosetting organopolysiloxane composition and 0.001 to 10 parts by weight of a lithium salt. 2. The silicone rubber composition for a semiconductive roller according to claim 1, wherein the thermosetting organopolysiloxane composition further contains a conductive material other than a lithium salt. 3. A thermosetting organopolysiloxane composition comprising: (A) 100 parts by weight of an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule, and (B) silicon in one molecule. Organohydrogenpolysiloxane containing at least 3 hydrogen atoms bonded to atoms 0.1 to 30 parts by weight, (C) conductive material other than lithium salt, volume resistivity of cured product is 1 × 10 ³ to 1 × 10 ^The silicone rubber composition for a semiconductive roller according to claim 2, wherein the silicone rubber composition has an amount of ¹⁰ Ω · cm and a catalytic amount of (D) a hydrosilylation reaction catalyst. 4. A thermosetting organopolysiloxane composition comprising: (A) 100 parts by weight of an organopolysiloxane containing at least two alkenyl groups bonded to silicon atoms in one molecule, and (C) a conductive material other than a lithium salt. ^{3. The} semiconductive roller according to claim 2, further comprising: (E) an organic peroxide catalyst amount, which is an amount of the cured material having a volume resistivity of 1 × 10 ³ to 1 × 10 ¹⁰ Ω · cm. Silicone rubber composition for use. 5. The conductive material is selected from conductive carbon black, conductive zinc white or conductive titanium oxide.
5. The silicone rubber composition for a semiconductive roller according to claim 2, which contains one or more kinds. 6. The lithium salt is dissolved in one or more kinds selected from an organic solvent and / or a liquid organic polymer, and the lithium salt is dissolved in one or more kinds. Silicone rubber composition for semiconductive roller. 7. The lithium salt is LiBF_Four, LiCl
O_Four, LiPF₆, LiAsF₆, LiSbF₆, LiSO
₃CF₃, LiN (SO₂CF₃)₂, LiSO₃C _FourF₉, L
iC (SO₂CF₃)₃, LiB (C₆H_Five)_FourChosen from
1 or 2 or more types, It is characterized by the above-mentioned.
6. Silicone rubber for semiconductive roller according to any one of 6
Composition. 8. A semiconductive roller comprising a cored bar on which a cured product layer of the silicone rubber composition for a semiconductive roller according to claim 1 is formed.