JPH093333A - Conductive silicone rubber composition and conductive silicone rubber roll using the same - Google Patents

Abstract

PURPOSE: To obtain a conductive silicone rubber compsn. which has an excellent moldability and gives a cured silicone rubber molding excellent in compression set properties and conductivity while having a low hardness and to obtain a conductive silicone rubber roll produced from the same. CONSTITUTION: This compsn. contains 100 pts.wt. linear high-molecular polyorganosiloxane which has a degree of polymn. of 3,000 or higher and of which 90mol% or higher of the side chains are methyl and 0.01-1.0mol % of them are vinyl, 40-100 pts.wt. low-molecular polyorganosiloxane which has a degree of polymn. of 50-1,000 and of which 50mol% or higher of the side chains are methyl, 1-15 pts.wt. carbon black comprising hollow shell particles and having a specific surface area of 500m<2> /g or higher, and a necessary amt. of a curative. A conductive silicone rubber roll is obtd. by forming a molded silicone rubber layer having a hardness (with a JIS A durometer) of 20 or lower from the compsn. on the surface of a metal roll core.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive silicone rubber which is excellent in molding processability and which, after being cured, can be obtained as a silicone rubber molded product which has a low hardness but is excellent in compression set resistance and conductivity. The present invention relates to a composition and a conductive silicone rubber roll using the composition.

[0002]

2. Description of the Related Art Various conductive rubbers in which a conductive material is blended with a rubber-like substance exhibiting electrical insulation have been known in the art. For example, by blending carbon black or the like as the conductive material, electrical resistance can be improved. Conductive rubber in the range of 10 ^{5 to} 10 Ω · cm is applied in various fields.

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.
Although it is used in various places as an electrically insulating rubber, it is also put into practical use as a conductive silicone rubber by adding a conductive material such as carbon black like other rubber-like substances.

In this case, as the conductive material added to the silicone rubber composition, for example, carbon-based powder such as carbon black and graphite, various metal powders such as silver, nickel and copper, non-conductive powder and short fibers. Examples thereof include those whose surface is treated with a metal such as silver, conductive fibers such as carbon fibers and metal fibers, or a mixture thereof. The volume resistivity of silicone rubber is 10 ¹⁰ ~ depending on the type of conductive material and the filling amount without impairing the properties of silicone rubber.
It is often used because it can be lowered to about 10 ^-3 Ω · cm. In particular, in the case of obtaining a highly conductive silicone rubber of 10 ⁵ Ω · cm or less, among the above conductive materials, metal powders such as carbon black, silver and nickel are mainly used. Black is often used.

The conductive silicone rubber as described above is
It is used for various purposes such as office equipment rolls, keyboard contacts, sheet heating elements, electromagnetic wave shielding materials, and more particularly fixing rolls for office machines such as copiers and facsimiles, paper feed rolls, developing rolls, transfer rolls, It is often used as a roll material such as a charging roll. By the way, with the recent miniaturization and speeding up of office equipment, it has been required for office equipment rolls to obtain a roll nip width with a small diameter roll, which requires a low hardness material for the roll material. ing.

[0006] To meet the demand for rolls for office equipment, silicone polymers that are commonly used are
It has a hardness of about 15 or more as measured by JIS / A type hardness tester without adding a filler. When carbon black is added to obtain conductivity, the hardness is further increased. It was difficult to obtain a conductive silicone rubber having a hardness of 20 or less with a silicone rubber composition. Further, it is possible to reduce the hardness by reducing the degree of crosslinking of the silicone polymer, but with this method, the compression set becomes large and the durability is greatly reduced.
It cannot be practically used as a roll for office equipment.

[0007]

As described above, the roll material for office equipment is required to have a low hardness, but the conventional conductive silicone rubber composition has a low hardness of, for example, 20 or less. There is a problem that it is difficult to obtain a conductive silicone rubber having hardness without impairing its durability, that is, without increasing compression set.

On the other hand, JP-A-55-120656 discloses that by using carbon black having hollow shell-shaped particles as a conductive material, good conductivity can be obtained with a small blending amount and physical properties after curing can be obtained. Curable liquid organopolysiloxane compositions having enhanced properties are described.

However, the main polymer used in the curable liquid organopolysiloxane composition has a viscosity of 10%.
Since it has a low viscosity of 0000 CS or less, it cannot be processed by, for example, two rolls, and it is difficult to uniformly disperse the unique carbon black as described above. Having and polymerization degree
Since a low molecular weight polyorganosiloxane of 50 or less is blended, there is a serious problem that this component volatilizes and the office equipment to which the conductive rubber roll is applied is easily contaminated.

The present invention has been made in order to solve such a problem, and is a silicone rubber molding which is excellent in molding processability and has low compression set after curing and excellent resistance to compression set and conductivity. The purpose of the present invention is to provide a conductive silicone rubber composition from which a body is obtained, and by using such a conductive silicone rubber composition, low hardness is achieved without impairing durability or conductivity. It is an object of the present invention to provide a conductive silicone rubber roll that makes it possible.

[0011]

The conductive silicone rubber composition of the present invention has (i) a degree of polymerization of 3000 or more, 90 mol% or more of side chain groups being a methyl group, and 0.01
~ 1.0 mol% vinyl group is a straight chain high molecular weight polyorganosiloxane 100 parts by weight, (b) polymerization degree is 50 ~ 1000
40 to 100 parts by weight of a linear or branched low molecular weight polyorganosiloxane in which 50 mol% or more of the side chain groups are methyl groups, and (c) a specific surface area of at least 500 m.
Carbon black with ² / g hollow shell particles 1 ~
It is characterized by containing 15 parts by weight and (d) a necessary amount of a curing agent.

Further, the conductive silicone rubber roll of the present invention is a conductive silicone rubber roll having a roll core metal and a conductive silicone rubber coated on the surface of the roll core metal, wherein the conductive silicone rubber is It is characterized in that it is composed of a rubber molding formed using the conductive silicone rubber composition of the present invention and has a hardness of 20 or less as measured by a JIS / A type rubber hardness meter.

The component (a) constituting the conductive silicone rubber composition of the present invention is a linear high molecular weight polyorganosiloxane having a degree of polymerization of 3000 or more and serves as a base polymer. If the degree of polymerization of this component (a) is less than 3000, the mechanical strength after curing will decrease and, for example,
It is not possible to obtain good molding workability, such as the workability (dividing property) of the two rolls is reduced. The more preferable degree of polymerization of component (a) is in the range of 5,000 to 10,000, and a high molecular weight polyorganosiloxane in this degree of polymerization range gives particularly good moldability and imparts good mechanical strength after curing. be able to.

The side chain group bonded to the silicon atom forming the main skeleton of the straight chain high molecular weight polyorganosiloxane of the component (a) has 90 mol% or more of the side chain group as a methyl group. When the methyl group as a side chain group is less than 90 mol%, the compression set becomes large. At least a part of the side chain group other than the methyl group is required to be an alkenyl group for curing the composition with the curing agent of the component (d) described in detail later, and in the present invention, particularly the heat resistance, etc. It is a vinyl group from the point. The side chain group other than the methyl group and the vinyl group is not particularly limited, but is preferably a phenyl group from the viewpoint of heat resistance and the like. The phenyl group is not necessarily required, but the vinyl group is contained in the range of 0.01 to 1.0 mol% of the side chain group. The amount of vinyl groups is 0.01 mol%
When it is less than 1.0, the compression set of the obtained conductive silicone rubber molded article increases, while when it exceeds 1.0 mol%, the hardness of the obtained conductive silicone rubber molded article increases and the rubber strength decreases. A more preferable range of the amount of vinyl group is 0.05 to 0.3 mol%. The molecular chain terminal of the high molecular weight polyorganosiloxane may have a structure blocked with a triorganosilyl group or a hydroxyl group.

The low molecular weight polyorganosiloxane of the component (b) in the composition of the present invention reduces the hardness of the conductive silicone rubber molded article without increasing the compression set of the resulting conductive silicone rubber molded article. It is a component that causes.
The low molecular weight polyorganosiloxane may have a linear or branched molecular structure, but it is important that the degree of polymerization is in the range of 50 to 1,000. (B)
When the low molecular weight polyorganosiloxane as a component has a degree of polymerization of less than 50, it exhibits volatility and causes problems such as contamination of applied equipment after molding and curing. On the other hand, if the degree of polymerization exceeds 1000, the above effect cannot be obtained.
The more preferable degree of polymerization of the low molecular weight polyorganosiloxane is in the range of 80 to 500 for the same reason.

The side chain group bonded to the silicon atom forming the main skeleton of the straight chain or branched low molecular weight polyorganosiloxane of the component (b) has 50 mol% or more of it as a methyl group. When the methyl group content is less than 50 mol%, the compatibility with the component (a) becomes poor and bleeding may occur after curing. A phenyl group is mentioned as a preferable side chain group other than a methyl group, but the most preferable form is that all side chain groups are methyl groups. However, a low molecular weight polyorganosiloxane in which 40 mol% or less of the side chain group is a phenyl group is also mentioned as a preferable form. In addition,
You may have one or less unsaturated groups in one molecule, but if the amount of unsaturated groups exceeds one in one molecule, the crosslink density will increase and it will be difficult to obtain low hardness. Become.

In the conductive silicone rubber composition of the present invention, the blending amount of the above-mentioned component (b) is important, and (a)
The range is 40 to 100 parts by weight based on 100 parts by weight of the high molecular weight polyorganosiloxane as a component. If the amount of the low molecular weight polyorganosiloxane as the component (b) is less than 40 parts by weight, the above effects cannot be obtained, and if it exceeds 100 parts by weight, for example, the workability with a two-roll roll deteriorates. However, good moldability cannot be obtained, and oil bleeding easily occurs after curing. (B)
A more preferable compounding amount of the components is in the range of 50 to 80 parts by weight for the same reason. The component (c) in the composition of the present invention is carbon black having a hollow shell-shaped particle and a specific surface area of at least 500 m ² / g. Therefore, it becomes possible to impart good conductivity. That is, the obtained conductive silicone rubber molded body is kept low in hardness and is given good conductivity. When the specific surface area of the component (c) is less than 500 m ² / g, it is not possible to obtain the good conductivity-imparting effect due to the small amount of the compound as described above. The more preferable specific surface area of the component (c) is 700 m ² / g or more. Specific examples of such a component (c) include Ketjen Black EC, Ketjen Black EC600JD (trade name, manufactured by Ketjen Black International).

The blending amount of the above-mentioned component (c) is determined by the intended conductivity, but in order to achieve a low hardness of the obtained conductive silicone rubber molded article,
The amount is 1 to 15 parts by weight with respect to 100 parts by weight of the high molecular weight polyorganosiloxane as the component (a). If the compounding amount of the component (c) exceeds 15 parts by weight, the hardness of the obtained conductive silicone rubber molded article will be high, and for example JIS.
Only a rubber molded product having a hardness of more than 20 according to the A-type rubber hardness tester can be obtained. Further, if the compounding amount of the component (c) is too small, sufficient conductivity cannot be imparted, so 1 part by weight or more is added to 100 parts by weight of the component (b). The more preferable compounding amount of the component (c) is in the range of 3 to 10 parts by weight.

The curing agent of component (d) in the composition of the present invention is a rubber-like elastic body (conductive silicone rubber molding).
It is appropriately selected according to the reaction mechanism for obtaining. As the reaction mechanism, (1) crosslinking reaction with an organic peroxide vulcanizing agent, (2) addition reaction and the like are known. The curing agent of the component (d) will be described below according to the reaction mechanisms of (1) and (2) above.

First, in the case of applying the crosslinking reaction of the above (1), as the curing agent of the component (d), benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dicumyl peroxide, cumyl-t-butyl peroxide,
2,5-dimethyl-2,5-di-t-butylperoxyhexane,
Various organic peroxide vulcanizing agents such as di-t-butyl peroxide are used. In addition, these organic peroxide vulcanizing agents are
Used as one kind or as a mixture of two or more kinds.

The compounding amount of the organic peroxide as the curing agent of the component (d) is 100 parts by weight of the high molecular weight polyorganosiloxane (silicone base polymer) of the component (a).
The content is preferably in the range of 0.05 to 15 parts by weight. If the blending amount of the organic peroxide is less than 0.05 parts by weight, vulcanization is not sufficiently performed, and the compression set increases, while if blending more than 15 parts by weight, there is no particular effect. There is a possibility that the physical properties of the obtained conductive silicone rubber molded product may be adversely affected.

When the addition reaction (2) is applied, a curing catalyst and a crosslinking agent are used as the curing agent of the component (d). For example, 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, and a hydrogen atom bonded to a silicon atom is used as a crosslinking agent. Polydiorganosiloxanes having an average of at least more than 2 in a molecule are used.

In the above-mentioned curing agent of component (d), the compounding amount of the curing catalyst is 1 to 1000 ppm in terms of platinum element based on 100 parts by weight of the high molecular weight polyorganosiloxane of component (b).
The amount in the range of is preferable. If the compounding amount of the curing catalyst is less than 1 ppm as the amount of platinum element, curing does not proceed sufficiently, and if the compounding amount exceeds 1000 ppm, no particular improvement in the curing rate can be expected. In addition, the amount of the cross-linking agent is (a)
The amount is preferably such that the number of hydrogen atoms bonded to the silicic group atoms in the cross-linking agent is 0.5 to 4.0, more preferably 1.0 to 3.0, per 1 alkenyl group in the component. If the amount of hydrogen atoms is less than 0.5, curing of the composition does not proceed sufficiently and the hardness after curing becomes too low, and if the amount of hydrogen atoms exceeds 4.0, physical properties after curing And the heat resistance decreases.

In the conductive silicone rubber composition of the present invention, if necessary, a filler other than the above-mentioned components (a) to (d),
For example, silanol group-containing silanes having a degree of polymerization of 100 or less, dispersants such as alkoxy group-containing silanes, heat resistance improvers such as iron oxide, cerium oxide and iron octylate, platinum compounds, iron oxides, azo compounds, titanium oxides, etc. Flame retardants, pigments, etc. may be added, and from the viewpoint of reinforcement, fumed silica, wet silica, fumed silica whose surface is hydrophobized or wet silica, fine silica powder such as quartz fine powder, diatomaceous earth, etc. ,
You may mix polyorganosilsesquioxane etc.
Further, a saturated aliphatic hydrocarbon such as an isoparaffin solvent and other additives to be added to other ordinary silicone rubber compositions may be blended for the purpose of imparting processability and moldability to the composition.

The conductive silicone rubber composition of the present invention comprises
It can be obtained by blending and kneading the above-mentioned components in a conventionally used apparatus such as a kneader, a Banbury mixer, and a mixing roll such as a two-roll mill. In addition, the conductive silicone rubber composition of the present invention,
The product can be molded and processed by a usual method such as pressure molding, extrusion molding, injection molding, calender molding or the like to be a product.

The conductive silicone rubber composition of the present invention comprises
It is particularly useful as a conductive silicone rubber roll material, and the conductive silicone rubber composition of the present invention is uniformly coated on a roll core according to a conventional method, and then cured to form a rubber molded body. A high performance conductive silicone rubber roll having a conductive silicone rubber coated on the surface can be obtained. The conductive silicone rubber roll of the present invention is one in which a conductive silicone rubber molding is formed using such a conductive silicone rubber composition of the present invention. Thus, by using the conductive silicone rubber composition of the present invention,
A conductive silicone rubber roll having a low hardness of 20 or less as measured by an A-type rubber hardness tester, a low compression set and high conductivity can be obtained. If the hardness of the conductive silicone rubber roll measured by the JIS / A type rubber hardness meter exceeds 20, an effective roll nip width cannot be obtained. Further, the conductivity of the conductive silicone rubber roll can attain, for example, 10 ⁵ Ω · cm or less in volume resistivity.

As described above, since the conductive silicone rubber roll of the present invention has low hardness, low compression set and high conductivity, it is a fixing roll for office equipment, a paper feed roll, a developing roll, a transfer roll, a charging roll. It is useful as a roll.

[0028]

Embodiments of the present invention will be described below. In addition, all "parts" in the following Examples and Comparative Examples represent "parts by weight".

EXAMPLE 1 Vinyl group-containing polydimethylsiloxane 100 containing 0.03 mol% of methylvinylsiloxane unit and having a degree of polymerization of about 7,000.
Ketjenblack EC-600JD (trade name, as carbon black with 50 parts of linear polydimethylsiloxane with a degree of polymerization of about 100 and hollow shell particles with a specific surface area of about 1300 m ² / g Ketjen Black International Co., Ltd.) was charged into an open kneader at a ratio of 5 parts, thoroughly mixed, and then uniformly dispersed with a three-roll mill. Then, with a 2-roll, 2,5-dimethyl-2,5-di-t-
A conductive silicone rubber composition was obtained by mixing 1 part of butylperoxyhexane.

Next, the above conductive silicone rubber composition is added.
Press vulcanized under the condition of 443K × 10 minutes, 200mm × 200mm × 2m
A rubber sheet of m and a cylinder having a diameter of 29 mm and a height of 12.7 mm were molded, and thereafter, vulcanization was performed in an oven at 473 K for 4 hours to prepare a conductive silicone rubber sheet and a cylinder piece.

In the above process, first, the distributability (thickness: 5 mm) of the conductive silicone rubber composition with a two-roll was evaluated. Then, using the conductive silicone rubber sheet having a thickness of 2 mm, the hardness is measured by a JIS / A type hardness meter according to JIS K-6301, and the volume is measured by using Loresta IP manufactured by Mitsubishi Petrochemical Co., Ltd. The resistivity was measured. Further, the compression set was measured using the above-mentioned cylindrical piece according to JIS K-6301 at 453K × 22h, 25% compression. The results are shown in Table 1 together with the compounding ratio of the conductive silicone rubber composition. Example 2 Vinyl group-containing polydimethylsiloxane 100 containing 0.07 mol% of methylvinylsiloxane unit and having a degree of polymerization of about 8000.
Ketjen black as a carbon black in which 70 parts of linear polydimethylsiloxane with a degree of polymerization of about 200 and hollow shell particles with a specific surface area of about 800 m ² / g
EC (made by Ketjen Black International) 7
The mixture was charged into an open kneader at a ratio of 1 part, mixed well, and then uniformly dispersed with a three-roll mill. Then, 1 part of 2,5-dimethyl-2,5-di-t-butylperoxyhexane was blended with a two-roll mill to obtain a conductive silicone rubber composition. The conductive silicone rubber composition thus obtained was used to evaluate the dispersibility with a two-roll roll in the same manner as in Example 1. Further, a conductive silicone rubber sheet and a cylindrical piece were prepared under the same conditions as in Example 1, and the characteristics of the conductive silicone rubber were evaluated in the same manner. The measurement results are shown in Table 1 together with the compounding ratio of the conductive silicone rubber composition.

Comparative Example 1 In the conductive silicone rubber composition of Example 1 above,
A conductive silicone rubber composition was produced in the same manner as in Example 1 except that polydimethylsiloxane having a degree of polymerization of about 6000 was used in place of the linear polydimethylsiloxane having a degree of polymerization of about 100. Further, using this conductive silicone rubber composition, the distributability by a two-roll was evaluated in the same manner as in Example 1, and a conductive silicone rubber sheet and a cylindrical piece were prepared under the same conditions as in Example 1, Similarly, the characteristics of the conductive silicone rubber were evaluated. The measurement results are shown in Table 1 together with the compounding ratio of the conductive silicone rubber composition.

Comparative Example 2 In the conductive silicone rubber composition of Example 1 above,
A conductive silicone rubber composition was produced in the same manner as in Example 1 except that polydimethylsiloxane having a degree of polymerization of about 30 was used instead of linear polydimethylsiloxane having a degree of polymerization of about 100. Further, using this conductive silicone rubber composition, the distributability by a two-roll was evaluated in the same manner as in Example 1, and a conductive silicone rubber sheet and a cylindrical piece were prepared under the same conditions as in Example 1, Similarly, the characteristics of the conductive silicone rubber were evaluated. The measurement results are shown in Table 1 together with the compounding ratio of the conductive silicone rubber composition.

Comparative Example 3 In the conductive silicone rubber composition of Example 1 above,
The amount of linear polydimethylsiloxane with a degree of polymerization of about 100 was set to 150 parts, and Ketjenblack EC-600 was used.
A conductive silicone rubber composition was produced in the same manner as in Example 1 except that the JD content was 10 parts. Also, using this conductive silicone rubber composition, in the same manner as in Example 1.
In addition to the evaluation of the distributability by using two rolls, Example 1
A conductive silicone rubber sheet and a cylindrical piece were prepared under the same conditions as above, and the characteristics of the conductive silicone rubber were evaluated in the same manner. The measurement results are shown in Table 1 together with the compounding ratio of the conductive silicone rubber composition.

Comparative Example 4 In the conductive silicone rubber composition of Example 1 above,
Same as Example 1 except that acetylene black (Denka Black: trade name, manufactured by Denki Kagaku Kogyo) having a specific surface area of about 60 m ² / g is used instead of carbon black (Ketjen Black EC-600SD). Then, a conductive silicone rubber composition was prepared. Further, using this conductive silicone rubber composition, the distributability by a two-roll was evaluated in the same manner as in Example 1, and a conductive silicone rubber sheet and a cylindrical piece were prepared under the same conditions as in Example 1, Similarly, the characteristics of the conductive silicone rubber were evaluated. The measurement results are shown in Table 1 together with the compounding ratio of the conductive silicone rubber composition.

Comparative Example 5 In the conductive silicone rubber composition of Example 1 above,
A conductive silicone rubber composition was produced in the same manner as in Example 1 except that a vinyl group-containing polydimethylsiloxane having a degree of polymerization of about 500 was used instead of the vinyl group-containing polydimethylsiloxane having a degree of polymerization of about 7,000. Further, using this conductive silicone rubber composition, the distributability by a two-roll was evaluated in the same manner as in Example 1, and a conductive silicone rubber sheet and a cylindrical piece were prepared under the same conditions as in Example 1, Similarly, the characteristics of the conductive silicone rubber were evaluated. The measurement results are shown in Table 1 together with the compounding ratio of the conductive silicone rubber composition.

[0037]

[Table 1] As is clear from Table 1, the conductive silicone rubber compositions according to Examples 1 and 2 are excellent in moldability and
It can be seen that low hardness, high conductivity and low compression set are obtained after curing. On the other hand, when the degree of polymerization of the low molecular weight polyorganosiloxane for lowering the hardness of the conductive silicone rubber molded product is outside the range of the present invention, the compression set is increased (Comparative Example 1), or after curing. Problems such as oil bleeding (Comparative Example 2) occur. It is also found that the same applies to the blending amount of the low molecular weight polyorganosiloxane.

Example 3 Vinyl group-containing polydimethylsiloxane 100 containing 0.05 mol% of methylvinylsiloxane unit and having a degree of polymerization of about 8000.
As a carbon black containing 70 mol of linear polymethylphenyl siloxane containing 10 mol% of phenyl groups and a degree of polymerization of about 300, and having a specific surface area of about 1300 m ² / g and hollow shell particles. Ketjen Black EC-600JD (trade name, made by Ketjen Black International) 6
The mixture was charged into an open kneader at a ratio of 1 part, mixed well, and then uniformly dispersed with a three-roll mill. Then, 0.01 parts of chloroplatinic acid made into a 10% isopropyl alcohol solution with a two-roll and 50 mol% of hydrogen atoms bonded to silicon atoms.
Methyl hydrogen siloxane with (degree of polymerization = about 10
0) 1.5 parts and 1 part of trialine isocyanurate were mixed to obtain a conductive silicone rubber composition.

The conductive silicone rubber composition thus obtained was used to evaluate the dispensability with a two-roll roll in the same manner as in Example 1. In addition, a conductive silicone rubber sheet and a cylindrical piece were prepared under the same conditions as in Example 1, and
Similarly, the characteristics of the conductive silicone rubber were evaluated. The measurement results are shown in Table 2 together with the compounding ratio of the conductive silicone rubber composition.

Comparative Example 6 In the conductive silicone rubber composition of Example 3 above,
In place of the vinyl group-containing polydimethylsiloxane having a degree of polymerization of about 8000, a vinyl group-containing polydimethylsiloxane containing 2 mol% of methylvinylsiloxane units and having a degree of polymerization of about 8000 is used, and the amount of methylhydrogensiloxane is compounded. A conductive silicone rubber composition was produced in the same manner as in Example 3 except that the amount was 3 parts. Further, using this conductive silicone rubber composition, the same procedure as in Example 3 was performed.
In addition to evaluating the dispensing property of this roll, a conductive silicone rubber sheet and a cylindrical piece were prepared under the same conditions as in Example 3, and the characteristics of the conductive silicone rubber were evaluated in the same manner. The measurement results are shown in Table 2 together with the compounding ratio of the conductive silicone rubber composition.

[0041]

[Table 2] As is clear from Table 2, the conductive silicone rubber composition according to Example 3 is excellent in molding processability, and also has low hardness, high conductivity and low compression set after being cured.

Example 4 The composition of the conductive silicone rubber produced in Example 1 was press-molded and vulcanized to a thickness of 7 mm on a stainless steel roll core having a diameter of 5 mm and a length of 230 mm. The surface of this was polished with a polishing machine so as to have a wall thickness of 6 mm, and a conductive silicone rubber roll was obtained.

The hardness of the conductive silicone rubber roll thus obtained was measured using a JIS / A type hardness meter.
Further, the roll was placed on an aluminum plate, a load of 500 g was applied to each end of the roll core metal, and the resistance between the core metal and the aluminum plate was measured using a digital multimeter R6871E manufactured by Advantest. Next, sandwich the roll between two aluminum plates with a thickness of 5 mm, put it in the oven compressed to a thickness of 4.5 mm, heat treat it under the condition of 453 K × 22 h, open the oven, and then let it come to room temperature. The wall thickness was measured for 30 minutes. Table 3 shows the measurement results.

Comparative Example 7 A conductive silicone rubber roll was prepared in the same manner as in Example 4 except that the conductive silicone rubber composition prepared in Comparative Example 1 was used. Further, using this conductive silicone rubber roll, the hardness and resistance were measured in the same manner as in Example 4, and the durability was evaluated. Table 3 shows the measurement results.

[0045]

[Table 3] As is clear from Table 3, the conductive silicone rubber roll according to Example 4 has high conductivity and low hardness, and is excellent in durability.

Even when the conductive silicone rubber composition of Example 3 was used, a similar high-performance conductive silicone rubber roll was obtained.

[0047]

As described above, according to the conductive silicone rubber composition of the present invention, it is possible to obtain a silicone rubber molded article having a low hardness after curing and excellent in compression set resistance and conductivity. In addition, good moldability can be obtained. Then, according to the conductive silicone rubber roll of the present invention formed by using such a conductive silicone rubber composition, without impairing the durability or conductivity,
It becomes possible to achieve low hardness. Therefore, it is possible to provide a conductive silicone rubber roll effective as a fixing roll, a paper feed roll, a developing roll, a transfer roll, a charging roll, etc. for office equipment.

[0048]

Claims (2)

[Claims] (A) The degree of polymerization is 3000 or more, 90 mol% or more of the side chain groups are methyl groups, and 0.01 to 1.0 mol.
100 parts by weight of a linear high molecular weight polyorganosiloxane in which% is a vinyl group, (b) the degree of polymerization is in the range of 50 to 1000, and 50 of the side chain groups
40 to 100 parts by weight of a straight or branched low molecular weight polyorganosiloxane having a mol% of at least a methyl group, and (c) a carbon black having hollow shell particles having a specific surface area of at least 500 m ² / g 1 to 15 A conductive silicone rubber composition, characterized in that it contains, by weight, (d) a necessary amount of a curing agent. 2. A conductive silicone rubber roll having a roll core and a conductive silicone rubber coated on the surface of the roll core, wherein the conductive silicone rubber is the conductive silicone rubber composition according to claim 1. A conductive silicone rubber roll characterized by comprising a rubber molded body formed by using a material, and having a hardness of 20 or less according to a JIS / A type rubber hardness meter.