JP3408326B2 - Conductive silicone rubber composition and silicone rubber roll - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a conductive silicone rubber composition having excellent conductive stability and thermal conductivity in the semiconductor region and also excellent compression set, and such a conductive silicone rubber composition. Relates to a silicone rubber roll.

[0002]

TECHNICAL BACKGROUND OF THE INVENTION AND PROBLEMS OF THE INVENTION Silicone rubber compositions which are cured into silicone rubber have been well known, and have excellent properties such as weather resistance, heat resistance, cold resistance and electric insulation. It is widely used as a potting material for electric and electronic parts, a coating material, and a molding material for molding. In addition, a conductive material such as conductive carbon black, graphite, and metal powder is blended with the silicone rubber composition, which is originally an insulating material, to have an electric resistance of 10 ^-1.
It has been put to practical use as a conductive silicone rubber in the range of ~ 10 ^-2 Ω · cm.

However, when a conductive carbon black is blended with silicone rubber to obtain a conductive silicone rubber molded product in the semiconductor region of about 10 ³ to 10 ¹⁰ Ω · cm, one molded product The variation of the electrical resistivity became extremely large, and it was difficult to stabilize the electrical resistivity.

It is considered that this is because a strain is generated inside the rubber during molding, and the uniform carbon chain changes due to the strain, and the carbon chain becomes sparse and dense.

As a method for solving this problem, a method of preparing conductive silicone rubber powder in advance and blending it with an insulating silicone rubber composition (Japanese Patent Laid-Open No. 61-108661).
JP, JP-A-63-156858, JP, JP-A-63
No. 251464), or a method in which a conductive silicone rubber composition containing carbon black and an insulating silicone rubber composition containing no carbon black are prepared in advance, and these are mixed and macro-dispersed (JP-A-3-190).
964).

However, in the former method of blending conductive silicone rubber powder, it is extremely difficult to obtain a uniform and stable conductive silicone rubber fine powder, and
Since the compound contains rubber powder, there is a problem in that roll processability, sheeting property and extrudability are difficult. Furthermore, in the case of a molded product obtained by such a method, when this is used for a rubber roll of a copying machine or the like, when polishing the surface, conductive rubber powder is scraped off and crater-like projections (holes) are formed on the surface. There is also a problem that it occurs and it takes a long time for polishing, and further, there is a problem that durability is deteriorated due to poor wear resistance when used as a rubber roll.

The latter method of mixing a silicone rubber composition containing carbon black and a silicone rubber composition not containing carbon black is a macroscopic dispersion of both to form a sea-island structure, and a stable conductive silicone rubber. However, there is a drawback in that the dispersibility is different depending on the kneading conditions when the compound is produced or when the molded product is processed, and the conductivity of the obtained silicone rubber varies. In addition, the molded product obtained by this method has weak mechanical strength, and due to mixing of silicone rubber compositions that are originally incompatible with each other, a layer peeling phenomenon occurs, and when used in a roll such as a copying machine, the conductivity is low. Similar to the case of blending the silicone rubber powder, craters were generated during polishing and the durability was lowered, and it was not usable in actual use.

As a compounding example other than carbon black, there has been proposed a method in which tin oxide, zinc oxide or the like is compounded to obtain a conductive silicone rubber (JP-A-3-190964). However, in order to obtain a conductive silicone rubber molded product in the semiconductor region by blending these conductive metal oxides, a large amount of conductive metal oxides must be blended, which results in a decrease in mechanical strength. However, there is a problem that the compression set becomes worse.

On the other hand, a method in which a filler such as quartz powder, aluminum oxide or boron nitride is mixed with silicone rubber to obtain a heat conductive silicone rubber is generally used. However, the above filler originally does not have conductivity, and when used in a heat roll of office equipment, there is a problem that paper jam easily occurs due to electrification. Further, even if carbon black or the like is added to prevent this, a large amount of the above filler is blended, so a large amount of carbon black must also be blended, resulting in high hardness and poor compression set. There was a problem that it would end up.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances and has excellent electrical conductivity and thermal conductivity in the semiconductor region while maintaining the original characteristics of silicone rubber, and is resistant to compression set. It is an object of the present invention to provide a conductive silicone rubber composition which is excellent and is particularly suitable as a silicone rubber roll material.

[0011]

The present inventors have conducted extensive studies to achieve the above object, and as a result, it is effective to blend a specific organopolysiloxane with a conductive metal oxide surface-treated with a surface-treating agent. It was found that there is something, and the present invention has been completed.

That is, the present invention provides (A) an organopolysiloxane represented by the following general formula (1):
100 parts by weight of R ¹ _a SiO _{(4-a) / 2} (1) (wherein R ¹ is the same or different unsubstituted or substituted monovalent hydrocarbon group, and a is a positive number from 1.90 to 2.05) () (B) Silane compound, silazane, polyorganosiloxane
A conductive silicone rubber composition characterized by comprising a conductive metal oxide 50-1000 parts by weight (C) a catalytic amount of a curing agent, which has been surface-treated in advance with a surface treatment agent selected from the above, and the like. A silicone rubber roll obtained by uniformly coating a conductive silicone rubber composition on a roll core metal and curing the same.

The present invention will be described in detail below.

The component (A) constituting the composition of the present invention is an organopolysiloxane represented by the above general formula (1), wherein R ¹ is a methyl group, an ethyl group, a propyl group, a butyl group or the like. Alkyl group, vinyl group, allyl group, alkenyl group such as butanyl group, phenyl group, aryl group such as tolyl group, or part or all of the hydrogen atoms bonded to carbon atoms of these groups may be replaced by halogen atom, cyano group, etc. The same or different unsubstituted or substituted monovalent hydrocarbon group selected from a substituted chloromethyl group, chloropropyl group, 3,3,3-trifluoropropyl group, 2-cyanoethyl group, etc., preferably having a carbon number 1-10, more preferably 1-8
belongs to. Also, a is a positive number from 1.90 to 2.05.

This compound preferably has a linear molecular structure, but there is no problem even if the molecule contains a partially branched molecular structure. Further, this may have a molecular chain terminal blocked with a triorganosilyl group or a hydroxyl group, and the triorganosilyl group may be a trimethylsilyl group, a dimethylvinylsilyl group, a methylphenylvinylsilyl group, or a methyldiphenyl group. Examples thereof include a silyl group, a methyldivinylsilyl group and a trivinylsilyl group.

The degree of polymerization of this material is not limited, but in the case of liquid silicone rubber, the degree of polymerization is 100 to 2000, and in the case of millable silicone rubber, the degree of polymerization is 2000 to 10
000 is preferred.

The component (B) of the present invention is a conductive metal oxide surface-treated with a surface-treating agent, and is a characteristic component for achieving the intended effect of the present invention.

Specific conductive metal oxides include oxides of titanium, tin and antimony, solid solutions of iron oxide (FeO) and titanium oxide (TiO ₂ ), magnesium oxide (MgO) and aluminum oxide (Al ₂ Solid solution with O ₃ ), tin oxide (SnO ₂ ).
Of antimony oxide (Ab ₂ O ₅ ), solid solution of indium oxide (In ₂ O ₃ ) and tin oxide (SnO ₂ ), oxides of aluminum, gallium, tin, indium, titanium and zinc oxide Solid solution is given. In addition, these solid solutions are used for magnesium, zinc, calcium, strontium, barium, titanium, etc. and their oxides, hydroxides,
It may be the one coated on the surface of a sulfide, a nitrate, or the like.

Of these, zinc oxide type is preferable because it is easy to control the electrical conductivity and thermal conductivity. In particular, a zinc oxide-aluminum oxide type is more preferable.

The average particle diameter of these (B) components is 100 μm
It is preferably not more than 50 μm, more preferably not more than 50 μm, further preferably not more than 10 μm. If the average particle size exceeds 100 μm, the mechanical strength may be weakened.

The specific resistance of this material is required to be 500 Ω · cm or less, and more preferably 300 Ω · cm or less. When the specific resistance exceeds 500 Ω · cm, the conductivity of the obtained silicone rubber may not be sufficiently exhibited.

The component (B) used in the present invention is obtained by surface-treating the above conductive metal oxide with a surface-treating agent.

Examples of the surface treatment agent include silane compounds, silazanes, polyorganosiloxanes and the like. However, considering the surface treatment effect on the conductive metal oxide, the silane compound is particularly preferable.

As the silane compound, vinyltrichlorosilane, vinyltriethoxysilane, vinyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3
-Chloropropylmethyldichlorosilane, 3-chloropropylmethyldiethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltriethoxysilane, 3-aminopropyltriethoxysilane, N
-(2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyl Dimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, diphenyldimethoxy. Examples thereof include silane, diphenyldiethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, diphenylsilanediol, dimethyldichlorosilane, and methyltrichlorosilane.

As the polyorganosiloxane,
Examples are shown by the following general formula, the degree of polymerization is 10
It is 0 or less, preferably 50 or less.

R _b SiO _{(4-b) / 2 In the} formula, R is hydrogen and / or a monovalent substituted or unsubstituted hydrocarbon group, and as the monovalent substituted or unsubstituted hydrocarbon group, Alkenyl group such as vinyl group, methyl group,
Unsubstituted carbonization such as ethyl group, propyl group, butyl group, hexyl group, alkyl group such as dodecyl group, aryl group such as phenyl group, aralkyl group such as β-phenylethyl group and β-phenylpropyl group Examples thereof include a hydrogen group and a substituted hydrocarbon group such as a chloromethyl group and a 3,3,3-trifluoropropyl group. In addition, a methyl group, a vinyl group, a phenyl group, and a 3,3,3-trifluoropropyl group are generally preferable. Also, b is a number from 0 to 3.0.

Examples of silazanes include hexamethyldisilazane and divinyltetramethyldisilazane.

These surface treatment agents may be used alone or in combination of two or more depending on the required characteristics of the present composition.

The amount of the surface treatment agent added is preferably 0.1 to 5% by weight, and more preferably 0.2 to 5% by weight, based on the amount of the conductive metal oxide.
It is 3% by weight.

[0030] As a method for surface treatment of the conductive metal oxides with these surface treatment agents, typically, the surface treatment agent added to the conductive metal oxide, a method of mixing is used in its ordinary stirrer such as a Henschel mixer To be When mixing,
It may be either heated at room temperature, but have preferably carried out under heating at about 100 to 300 ° C..

The surface-treated conductive metal oxide as the component (B) is not limited to one type, and two or more types can be used in combination.

The content of the component (B) is 50 to 10 parts by weight based on 100 parts by weight of the organopolysiloxane of the component (A).
It is 00 parts by weight, preferably 100 to 500 parts by weight.
If it exceeds 1000 parts by weight, the mechanical strength of the cured product may decrease, and if it is less than 50 parts by weight, the desired conductivity may not be obtained.

The curing agent as the component (C) is appropriately selected according to the reaction mechanism for obtaining the rubber elastic body. As the reaction mechanism, (1) a crosslinking method using an organic peroxide vulcanizing agent, (2) a condensation reaction method, (3) an addition reaction method, etc. are known.
It is well known that the preferred combination of component (A) and component (C), i.e. a curing catalyst or crosslinking agent, and the amount of component (C) are determined.

The (A) organopolysiloxane and (D) curing agent in the reaction mechanisms (1) to (3) will be described below.

First, when the crosslinking method (1) is applied, at least two of the organic groups bonded to silicon atoms in one molecule are usually vinyl as the organopolysiloxane of the component (A). , Propenyl, butenyl,
An organopolysiloxane that is an alkenyl group such as hexenyl is used. Of these groups, the vinyl group is particularly preferred because it is easy to synthesize and the raw materials are easily available. Further, as the curing agent of the component (C), benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, cumyl-t-butyl peroxide, 2,5
Various organic peroxide vulcanizing agents such as -dimethyl-2,5-di-t-butylperoxyhexane and di-t-butylperoxide are used. Since they give particularly low compression set, dicumyl peroxide, Cumyl-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, di-t-butyl peroxide are preferred. In addition, these organic peroxide vulcanizing agents are used as one kind or as a mixture of two or more kinds.

The blending amount of the organic peroxide as the curing agent of the component (C) is preferably 0.05 to 15 parts by weight with respect to 100 parts by weight of the organopolysiloxane of the component (A). If the amount of the organic peroxide is less than 0.05 parts by weight, vulcanization is not sufficiently performed,
This is because, if the amount is more than 15 parts by weight, not only there is no particular effect, but also the physical properties of the obtained conductive silicone rubber may be adversely affected.

When the condensation reaction of the above (2) is applied, an organopolysiloxane having hydroxyl groups at both ends is used as the organopolysiloxane of the component (A). As the curing agent for the component (C), first, as a cross-linking agent, ethyl silicate, propyl silicate, methyltrimethoxysilane, vinyltrimethoxysilane, methyltriethoxysilane, vinyltriethoxysilane, methyltris (methoxyethoxy) silane, vinyltris ( Alkoxy type such as methoxyethoxy) silane and methyltripropenoxysilane; acetoxy type such as methyltriacetoxysilane and vinyltriacetoxysilane; methyltri (acetoneoxime) silane, vinyltri (acetoneoxime) silane, methyltri (methylethylketoxime) silane, Examples thereof include vinyltri (methylethylketoxime) silane and the like, and partial hydrolysates thereof. Hexamethyl-bis (diethylaminoxy)
Cyclotetrasiloxane, tetramethyldibutyl-bis (diethylaminoxy) cyclotetrasiloxane, heptamethyl (diethylaminoxy) cyclotetrasiloxane, pentamethyl-tris (diethylaminoxy) cyclotetrasiloxane, hexamethyl-bis (methylethylaminoxy) cyclotetrasiloxane, Cyclic siloxanes such as tetramethyl-bis (diethylaminoxy) -mono (methylethylaminoxy) cyclotetrasiloxane are also exemplified. As described above, the cross-linking agent may have a silane or siloxane structure, and the siloxane structure may have a linear, branched or cyclic structure. Furthermore, when these are used, it is not necessary to be limited to one type, and two or more types can be used in combination.

Further, among the curing agents of the component (C), as the curing catalyst, iron octoate, cobalt octoate,
Carboxylic acid metal salts such as manganese octoate, tin naphthenate, tin caprylate, tin oleate; dimethyltin dioleate, dimethyltin dilaurate,
Organotin compounds such as dibutyltin diacetate, dibutyltin dioctoate, dibutyltin dilaurate, dibutyltin dioleate, diphenyltin diacetate, dibutyltin oxide, dibutyltin dimethoxide, dibutylbis (triethoxysiloxy) tin, dioctyltin dilaurate are used.

In the curing agent as the component (C), the amount of the crosslinking agent is preferably 0.1 to 20 parts by weight based on 100 parts by weight of the organopolysiloxane as the component (A). The amount of cross-linking agent used is 0.1
If it is less than 10 parts by weight, the rubber after curing will not have sufficient strength, and if it exceeds 20 parts by weight, the obtained rubber will become brittle.
Both are unbearable for practical use. Also, the amount of the curing catalyst compounded is
(A) 100 parts by weight of organopolysiloxane is 0.
01 to 5 parts by weight is preferred. If the amount is less than this, it is insufficient as a curing catalyst, and it takes a long time to cure, and the curing in the interior far from the contact surface with air becomes poor. On the other hand, if the amount is larger than this, the storage stability will decrease. A more preferable range of blending amount is 0.1 to 3 parts by weight.

(A) when applying the addition reaction of (3) above
As the component organopolysiloxane, those similar to the organopolysiloxane in (1) above are used. Further, as the curing agent of the component (C), a platinum catalyst such as chloroplatinic acid, a platinum olefin complex, a platinum vinyl siloxane complex, platinum black, or a platinum triphenylphosphine complex is used as a curing catalyst. An organopolysiloxane having at least an average of more than 2 hydrogen atoms bonded to silicon atoms in one molecule is used.

In the curing agent as the component (C), the amount of the curing catalyst is preferably such that the amount of platinum element is in the range of 1 to 1000 ppm with respect to 100 parts by weight of the organopolysiloxane as the component (A). If the compounding amount of the curing catalyst is less than 1 ppm as the amount of platinum element, the curing does not proceed sufficiently, and if it exceeds 1000 ppm, no particular improvement in the curing rate can be expected. The amount of the cross-linking agent to be blended is preferably such that 0.5 to 4.0 hydrogen atoms bonded to silicon atoms in the cross-linking agent per one alkenyl group in the component (A), and more preferably 1.0. ~ 3.
The amount is 0. When the amount of hydrogen atoms is less than 0.5, curing of the composition does not proceed sufficiently, the hardness of the composition after curing becomes low, and the amount of hydrogen atoms is 4.0
If the number exceeds the limit, the physical properties and heat resistance of the composition after curing will deteriorate.

In the composition of the present invention, a dispersant such as a low molecular weight siloxane having a degree of polymerization of 100 or less, a silanol group-containing silane, an alkoxy group-containing silane, iron oxide, cerium oxide, iron octylate, etc. may be added, if necessary. Heat resistance improver,
Flame retardants such as platinum compounds, iron oxides, azo compounds, titanium oxides, pigments, etc., and fumed silica from the aspect of reinforcement,
Wet silica, fumed silica whose surface has been hydrophobized or wet silica, fine silica powder such as quartz fine powder, diatomaceous earth, and polyorganosilsesquioxane may be added, and the composition may be processed and molded. For the purpose of imparting properties, saturated aliphatic hydrocarbons such as isoparaffin solvent, and other additives which are added to ordinary silicone rubber compositions can be added.

As the method for producing the composition of the present invention, the kneader, Banbury mixer, mixing roll and the like may be used for compounding and kneading with a conventionally used apparatus.

Further, the conductive silicone rubber composition of the present invention can be molded and processed by a usual method such as pressure molding, extrusion molding, injection molding, calender molding and the like to be made into a product.

Particularly, the conductive silicone rubber composition of the present invention is useful as a silicone rubber roll material, and the conductive silicone rubber composition of the present invention is uniformly coated and cured on a roll core metal as in a conventional method. As a result, a silicone rubber roll having excellent performance can be obtained.

[0046]

EFFECTS OF THE INVENTION According to the present invention, a molded article can be provided with a silicone rubber which is excellent in electrical conductivity stability and thermal conductivity in the semiconductor region and has mechanical strength maintained, and in particular has a small compression set. Therefore, the conductive silicone rubber composition and the cured product of the present invention are effectively used in a wide range of fields such as a rubber member such as a packing material, a field of electric industry, and a field of transportation equipment such as automobile parts, and particularly dry copying. It is useful for machine and printer rolls and industrial rolls.

[0047]

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. In the following examples, parts are parts by weight. Example 1 To 100 parts of a solid solution of zinc oxide and aluminum oxide (“conductive zinc flower” manufactured by Honjo Chemical Co., Ltd.), 1 part of vinyltriethoxysilane was added as a surface treatment agent, and the mixture was homogenized using a Henschel mixer. And disperse into 1
Heat treatment was carried out for an hour to obtain a conductive metal oxide A.

Then, methyl vinyl siloxane unit 0.15
A compound was prepared by mixing and kneading 100 parts of dimethylpolysiloxane (average degree of polymerization of about 6000) containing 300% by mol of the above-mentioned conductive metal oxide A using a kneader. Next, to 100 parts of this compound, 1.0 part of 2,5-dimethyl-2,5-di-t-butylperoxyhexane as a curing agent was mixed and kneaded using a two-roll mill, and the thickness was 2 mm. And 1 mm sheet, 150 mm long, 50 horizontal
A rectangular parallelepiped piece having a size of 15 mm and a height of 15 mm was prepared, and physical properties were evaluated using a 2 mm sheet, volume resistivity was measured using a 1 mm sheet, and thermal conductivity was evaluated using a rectangular parallelepiped piece. The sample sheet was press-vulcanized at 170 ° C for 10 minutes after forming the sheet, then 20
It was prepared by post-vulcanization at 0 ° C. for 4 hours. The physical properties were measured according to JIS K 6301, and the volume resistivity was 100 using Hiresta IP (manufactured by Mitsubishi Petrochemical Co., Ltd.).
Five points were measured in the sheet by applying V. The thermal conductivity was measured using "Shotherm QTM-DII rapid thermal conductivity meter" (Showa Denko KK) . Comparative Example 1 A compound and sheet were used in the same manner as in Example 1 except that the surface-treated "conductive zinc flower" (manufactured by Honjo Chemical Co., Ltd.) was used in place of the conductive metal oxide A of Example 1. A rectangular parallelepiped piece was prepared and evaluated. Comparative Example 2 Instead of 300 parts of the conductive metal oxide A of Example 1, acetylene black (“Denka Black” Denki Kagaku Kogyo Co., Ltd.) was used.
Compound, sheet and rectangular parallelepiped piece were prepared and evaluated in the same manner as in Example 1 except that 15 parts were mixed. Comparative Example 3 A compound, sheet and rectangular parallelepiped piece were prepared in the same manner as in Example 1 except that aluminum oxide (“AS-40” manufactured by Showa Denko KK) was used in place of the conductive metal oxide A of Example 1. It was prepared and evaluated.

The results are shown in Table 1.

[0050]

[Table 1]

Examples 2 to 4 100 parts of a solid solution of zinc oxide and tin oxide (“Pastran 2100” manufactured by Mitsui Mining & Smelting Co., Ltd.) was used as a surface treatment agent containing 50 mol% of methyl hydrogen siloxane units as methyl. Add 1 part hydrogen polysiloxane,
After evenly dispersing with a Henschel mixer, 150
It heat-processed at 2 degreeC for 2 hours, and the conductive metal oxide B was obtained.

Further, the same treatment as above was carried out using a titanium oxide whose surface was coated with a solid solution of tin oxide and antimony oxide (“W-1” manufactured by Mitsubishi Materials Corp.) to obtain a conductive material. A metal oxide C was obtained.

The same treatment as described above was performed using barium sulfate whose surface was coated with a solid solution of tin oxide and antimony oxide (“Pastran 4110” manufactured by Mitsui Mining & Smelting Co., Ltd.), and the conductivity was increased. A metal oxide D was obtained.

Then, methyl vinyl siloxane unit 0.2
To 100 parts of dimethylpolysiloxane (average degree of polymerization: about 8000) containing mol%, 250 parts of each of the above conductive metal oxides B to D were mixed and kneaded using a kneader to prepare a compound. Next, with 100 parts of these compounds, 1.0 part of 2,4-dichlorobenzoyl peroxide as a curing agent was mixed and kneaded using a double roll, and then 2 parts of
mm and 1 mm, then hot air vulcanization was performed at 200 ° C for 15 minutes, then postvulcanization at 200 ° C for 4 hours to prepare a sheet and rectangular parallelepiped pieces. The same evaluation as in Example 1 was performed.

The results are shown in Table 2.

[0056]

[Table 2]

Comparative Examples 4 to 6 Sheets and rectangular parallelepiped pieces were prepared in the same manner as in Examples 2 to 4 except that the conductive metal oxides used in Examples 2 to 4 were blended without surface treatment. An evaluation was made. Comparative Example 7 Example except that quartz powder (“Crystallite VX-S” manufactured by Tatsumori) was used in place of the conductive metal oxide B used in Example 2.
A sheet and a rectangular parallelepiped piece were produced in the same manner as in 2, and evaluated. Comparative Example 8 Instead of the conductive metal oxide B used in Example 2 , aluminum oxide (“alumina AS-40” manufactured by Showa Denko KK) 250
And 30 parts of acetylene black (“Denka Black” manufactured by Denki Kagaku Kogyo Co., Ltd.) were blended, and a sheet and a rectangular parallelepiped piece were prepared and evaluated in the same manner as in Example 2 .

The results are shown in Table 3.

[0059]

[Table 3]

Example 5 To 100 parts of a solid solution of zinc oxide and tin oxide (“Pastran 2100” manufactured by Mitsui Mining & Smelting Co., Ltd.), 1 part of dimethyldimethoxysilane as a surface treatment agent was added, and a Henschel mixer was used. After being uniformly dispersed, heat treatment was performed at 150 ° C. for 1 hour to obtain a conductive metal oxide E.

Next, 100 parts of dimethylpolysiloxane (average degree of polymerization: about 800) whose molecular chain ends were blocked with dimethylvinylsilyl groups were mixed and kneaded with 200 parts of the above conductive metal oxide E using a kneader. , A compound was prepared. Next, to 100 parts of this compound, 50 mol% of methyl hydrogen siloxane unit was used as a curing agent.
After mixing 2 parts of contained methyl hydrogen polysiloxane (average degree of polymerization of about 20), 1 part of trialine isocyanurate and 0.001 part of chloroplatinic acid, and mixing and kneading,
A sheet and a rectangular parallelepiped piece were prepared and evaluated in the same manner as in Example 1. Comparative Example 9 A compound, a sheet, and a sheet were prepared in the same manner as in Example 6 except that the surface-treated "Pastran 2100" (manufactured by Mitsui Mining & Smelting Co., Ltd.) was used in place of the conductive metal oxide E of Example 5 .
A rectangular parallelepiped piece was prepared and evaluated.

The results are shown in Table 4.

[0063]

[Table 4]

Example 6 A composition similar to that of Example 1 was applied onto a stainless steel core having a length of 25 cm and a diameter of 5 mm at a thickness of 6 mm at 170 ° C.
After press vulcanization in 15 minutes, atto vulcanization was performed in an oven at 200 ° C for 4 hours to prepare a silicone rubber roll, and Hiresta IP (manufactured by Mitsubishi Petrochemical Co., Ltd.) was used to apply 100 V to the core and roll. The volume resistivity between the surfaces was measured at 10 points. Comparative Example 10 A roll was prepared and evaluated in the same manner as in Example 6 except that the same composition as in Comparative Example 8 was used.

The results are shown in Table 5.

[0066]

[Table 5]

Claims (4)

(57) [Claims] (A) R ¹ _a SiO _{(4-a) / 2} (1) (wherein R ¹ is the same or different) in 100 parts by weight of the organopolysiloxane represented by the following general formula (1): Unsubstituted or substituted monovalent hydrocarbon group, a is a positive number from 1.90 to 2.05.) (B) Silane compound, silazane, polyorganosiloxane
A conductive silicone rubber composition comprising a conductive metal oxide preliminarily surface-treated with a surface-treating agent selected from 50 to 1000 parts by weight (C) of a catalytic amount of a curing agent. 2. The conductive silicone rubber composition according to claim 1, wherein the conductive metal oxide as the component (B) is conductive zinc oxide. 3. The conductive metal oxide as the component (B) is a zinc oxide-aluminum oxide conductive zinc oxide.
The conductive silicone rubber composition described. 4. A silicone rubber roll obtained by uniformly coating and curing the conductive silicone rubber composition according to claim 1 on a roll core metal.