JPH11158383A - Heat conductive silicone rubber composition and fixing roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a heat conductive silicone rubber composition capable of forming a silicone rubber having a high heat conductivity and a high impact resilience and to provide a fixing roll formed by using the composition and excellent in copying durability. SOLUTION: This heat conductive silicone rubber composition comprises (A) 100 pts.wt. diorganopolysiloxane having average >=3 silicon atom-bonded alkenyl groups in the side chain of one molecule, (B) 50-500 pts.wt. alumina fine powder having 0.1-50 μm average particle diameter, (C) an organopolysiloxane having at least 2 silicon atom-bonded hydrogen atoms in one molecule (in an amount so as to provide 0.3-1.2 mol silicon atom-bonded hydrogen atoms in the component C based on 1 mol alkenyl groups in the component A) and (D) a catalytic amount of a platinum-based catalyst. Furthermore, the fixing roll comprises a fluororesin layer or a fluororubber layer 3 formed through a silicone rubber layer 2 composed of a cured product of the heat conductive silicone rubber composition on the outer peripheral surface of a roll shaft 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermally conductive silicone rubber composition and a fixing roll formed by using the composition, and more particularly, to a high resilient rubber having high thermal conductivity. The present invention relates to a thermally conductive silicone rubber composition capable of forming a silicone rubber having the following, and a fixing roll formed using this composition and having excellent copying durability.

[0002]

2. Description of the Related Art A thermally conductive silicone rubber composition obtained by blending a large amount of silica fine powder or alumina fine powder with a silicone rubber composition in order to improve the thermal conductivity of the silicone rubber is already known. However, silicone rubber obtained by curing such a thermally conductive silicone rubber composition has low resilience, and when used as an outer covering material of a fixing roll used in an electrophotographic copying machine or a printer, There is a problem that the copying durability is poor.

[0003]

DISCLOSURE OF THE INVENTION The present inventors have intensively studied the above-mentioned problems, and as a result, have reached the present invention. That is, an object of the present invention is to provide a thermally conductive silicone rubber composition capable of forming a silicone rubber having high repulsive elasticity despite having high thermal conductivity, and a composition formed using this composition. Another object of the present invention is to provide a fixing roll having excellent copying durability.

[0004]

The heat conductive silicone rubber composition of the present invention comprises (A) a diorganopolysiloxane having an average of three or more silicon-bonded alkenyl groups in the side chain of one molecule.
0 parts by weight, (B) 50 to 500 parts by weight of alumina fine powder having an average particle diameter of 0.1 to 50 μm, (C) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule. The silicon-bonded hydrogen atom in this component is in the range of 0.3 to 1. based on 1 mol of the alkenyl group in component (A).
And (D) a catalytic amount of a platinum-based catalyst.

Further, the fixing roll of the present invention is a fixing roll having a fluororesin layer or a fluororubber layer formed on the outer peripheral surface of a roll shaft via a silicone rubber layer,
The silicone rubber forming the silicone rubber layer is obtained by curing the heat conductive silicone rubber composition according to claim 1.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The thermally conductive silicone rubber composition of the present invention will be described in detail. The diorganopolysiloxane of the component (A) is a main component of the present composition, and is characterized by having an average of three or more silicon-bonded alkenyl groups in one molecular side chain. This is because if the number of alkenyl groups bonded to the silicon atom in the side chain in one molecular chain is less than 3 on average, the resulting silicone rubber has a low elastic modulus. Although the molecular structure of the component (A) is substantially linear,
Part of the molecular chain may be branched. Examples of the alkenyl group in the component (A) include a vinyl group, an allyl group, a butenyl group, a pentenyl group, a hexenyl group, and a heptenyl group, and a vinyl group is particularly preferable. Also,
Examples of the group that binds to a silicon atom other than the alkenyl group in the component (A) include an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and a hexyl group; a phenyl group, a tolyl group, and a xylyl group. Aralkyl groups such as benzyl group and phenethyl group; halogenated alkyl groups such as 3-chloropropyl group and 3,3,3-trifluoropropyl group; alkoxy groups such as methoxy group and ethoxy group, and hydroxyl group. And particularly preferably a methyl group. The viscosity of the component (A) is not limited, but the viscosity at 25 ° C. is preferably not less than 1,000 centipoise, and the viscosity at 25 ° C. Is preferably in the range of 1,000 to 1,000,000 centipoise, and in particular, the viscosity at 25 ° C is 1
Preferably, it is in the range of from 0.000 to 500,000 centipoise.

Examples of the diorganopolysiloxane of the component (A) include a methylvinylsiloxane-dimethylsiloxane copolymer having trimethylsiloxy groups at both ends of the molecular chain, a methylvinylpolysiloxane having trimethylsiloxy groups at both ends of the molecular chain, Methyl vinyl siloxane / dimethyl siloxane copolymer with dimethyl vinyl siloxy group at both ends of chain, methyl vinyl polysiloxane with dimethyl vinyl siloxy group at both ends of molecular chain, methyl vinyl siloxane / dimethyl siloxane copolymer with silanol group at both ends of molecular chain, molecule A methylvinylpolysiloxane having silanol groups at both ends of the chain, a diorganopolysiloxane in which a part of the methyl groups in these diorganopolysiloxanes is substituted with a phenyl group, a 3,3,3-trifluoropropyl group,
And mixtures of two or more of these diorganopolysiloxanes. If the number of alkenyl groups bonded to silicon atoms in the side chain in one molecular chain is 3 or more on average, the number of alkenyl groups bonded to silicon atoms in the side chain in one molecular chain is three. Dimethylpolysiloxane capped with dimethylvinylsiloxy groups at both ends of the molecular chain, dimethylpolysiloxane capped with trimethylsiloxy groups at both ends of the molecular chain, dimethylpolysiloxane capped with silanol groups at both ends of the molecular chain, and methyl groups in the diorganopolysiloxane May be substituted with a phenyl group, 3,3,3-trifluoropropyl group or the like.

The alumina fine powder of the component (B) is a component for improving the thermal conductivity and mechanical properties of the silicone rubber obtained by curing the present composition. The reason that the component (B) as the heat conductive filler is limited to alumina fine powder is that, when a filler such as silica fine powder is used as the heat conductive filler, even if the component (A) is used, Even if such a diorganopolysiloxane is used, it has high thermal conductivity,
Further, it is difficult to form a silicone rubber having high resilience. The shape of the component (B) is not limited, and may be spherical or irregular. Also,
The average particle size of the component (B) is in the range of 0.1 to 50 μm, but since the mechanical properties of the silicone rubber obtained by curing the present composition can be further improved,
It is preferable that the thickness be in the range of 0.1 to 10 μm. (B)
As the alumina fine powder of the component, a powder whose surface is treated with an organosilicon compound such as an organoalkoxysilane, an organohalosilane, or an organosilazane may be used. As the alumina fine powder, those previously surface-treated with the above-mentioned organosilicon compound may be used, and when this is blended with the component (A), the above-mentioned organosilicon compound may be blended into this system. May be used to treat this surface.

The amount of the component (B) is in the range of 50 to 500 parts by weight per 100 parts by weight of the component (A), and the resilience of the silicone rubber obtained by curing the composition is determined. In order to further improve the content, the content is preferably in the range of 50 to 300 parts by weight based on 100 parts by weight of the component (A).

The organopolysiloxane of the component (C) is a component for curing the present composition, and is characterized by having at least two silicon-bonded hydrogen atoms in one molecule. The molecular structure of the component (C) is not limited, and may be linear, partially branched linear, branched, or cyclic, and in particular, linear or partially branched linear. Is preferred. The bonding position of the silicon-bonded hydrogen atom in the component (C) is not limited, and examples thereof include a molecular chain terminal and / or a molecular chain side chain. Examples of the group other than the hydrogen atom bonded to the silicon atom in the component (C) include an alkyl group such as a methyl group, an ethyl group and a propyl group; an aryl group such as a phenyl group, a tolyl group and a xylyl group; a benzyl group and a phenethyl group Aralkyl groups such as 3-chloropropyl group and 3,3,3-trifluoropropyl group; and a methyl group is particularly preferable.

Examples of the organopolysiloxane of the component (C) include dimethylpolysiloxane having dimethylhydrogensiloxy groups at both ends of molecular chains, methylhydrogenpolysiloxane having dimethylhydrogensiloxy groups at both ends of molecular chains, and methylhydrogenpolysiloxane having both ends of molecular chains. Terminal dimethyl hydrogen siloxy group-blocked dimethyl siloxane / methyl hydrogen siloxane copolymer, molecular chain both terminal trimethyl siloxy group-blocked methyl hydrogen polysiloxane,
Trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer at both molecular chain terminals, Silanol group-blocked methylhydrogenpolysiloxane at both molecular chain terminals, dimethylsiloxane / methylhydrogensiloxane copolymer blocked at both molecular chain terminal silanol groups,
An organopolysiloxane comprising a siloxane unit represented by the formula: (CH ₃ ) ₃ SiO _1/2 , a siloxane unit represented by the formula: (CH ₃ ) ₂ HSiO _1/2 , and a siloxane unit represented by the formula: SiO _4/2 , wherein: the siloxane units represented by the formula _{(CH 3) 2 HSiO 1/2:} SiO 4 / organopolysiloxane composed of siloxane units represented by _2, the formula: (C
H ₃ ) A siloxane unit represented by HSiO _2/2 and a formula: CH ₃
Siloxane unit represented by SiO _3/2 or formula: HSi
An organopolysiloxane comprising a siloxane unit represented by O _3/2 , an organopolysiloxane in which a part of the methyl group of these organopolysiloxanes is substituted with a phenyl group, a 3,3,3-trifluoropropyl group, and the like; And mixtures of two or more of these organopolysiloxanes.

The amount of component (C) is such that the amount of silicon-bonded hydrogen atoms in this component is in the range of 0.3 to 1.2 moles per mole of alkenyl group in component (A). Preferably, the amount is such that the silicon-bonded hydrogen atoms in the component are in the range of 0.5 to 1.0 mol per 1 mol of the alkenyl group in the component (A).

The platinum catalyst as the component (D) is a catalyst for accelerating the curing of the present composition. Such platinum catalysts of component (D) include platinum fine powder, platinum-supported alumina powder, platinum-supported silica powder, platinum-supported carbon powder,
Chloroplatinic acid, an alcohol solution of chloroplatinic acid, an olefin complex of platinum, an alkenylsiloxane complex of platinum, a carbonyl complex of platinum, an acrylic resin,
Examples thereof include resin powders dispersed in a thermoplastic resin such as a polycarbonate resin, a polystyrene resin, and a silicone resin.

The amount of the component (D) is a catalytic amount, and is not limited as long as it can promote the curing of the present composition. The amount of the platinum metal in the component (D) is preferably in the range of 0.01 to 500 ppm, and in particular, the amount of the platinum metal in the component (D) is 0.1 to 0.1 parts by weight with respect to the component (A). Preferably, the amount is in the range of 100 ppm to 100 ppm.

The present composition comprises at least the above components (A) to (D), and as other optional components, 3-methyl-1-butyn-3-ol and 3,5-dimethyl-1-ol.
Hexin-3-ol, 3-phenyl-1-butyne-3
Acetylenic compounds such as -ol; 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexene-
Enyne compounds such as 1-yne; 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,3
Alkenylsiloxane compounds such as 5,7-tetrahexenylcyclotetrasiloxane; triazole compounds such as benzotriazole; other phosphine compounds;
A curing inhibitor for adjusting the storage stability and curability of the composition, such as a mercaptan compound or a hydrazine compound, can be blended. The amount of such a curing inhibitor is not limited, but is practically preferably 0.001 to 5 parts by weight based on 100 parts by weight of the component (A).

[0016] The composition of the present invention contains fumed silica, precipitated silica, and the like, in order to improve the mechanical properties of the obtained silicone rubber and to impart electrical conductivity within a range not to impair the object of the present invention. Fillers such as calcined silica, crushed quartz, diatomaceous earth, carbon black, silver powder, and nickel powder may be blended. In order to reduce the compression set of the obtained silicone rubber, a six-membered ring having a carbon-nitrogen unsaturated bond in a ring of pyridine, pyrimidine, 1,3,5-triazine or the like is used in the present composition. Compound,
Alternatively, a trace amount of a derivative thereof may be blended. Further, the composition may further contain known pigments, dyes, heat-resistance imparting agents, flame-retardant imparting agents, roll workability improvers, and the like, if necessary.

The composition comprises the above components (A) to (D),
And other components are mixed.
As a method for preparing the present composition, the components (A) to
The component (D) and other components can be prepared by a kneading device such as a kneader mixer, a loss mixer, a Henschel mixer or the like.

Next, the fixing roll of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the fixing roll of the present invention is characterized in that a fluororesin layer or a fluororubber layer 3 is formed on the outer peripheral surface of a roll shaft 1 via a silicone rubber layer 2. The material of the roll shaft 1 is as follows.
Examples include iron, stainless steel, copper, and aluminum. The silicone rubber forming the silicone rubber layer 2 is obtained by curing the above silicone rubber composition. Examples of the fluororesin forming the fluororesin layer include polytetrafluoroethylene resin (PTFE), tetrafluoroethylene / perfluoroalkylvinyl ether copolymer resin (PFA), and fluoroethylene / polypropylene copolymer resin (FEP). ),
Tetrafluoroethylene / ethylene copolymer resin (ET
FE), polychlorotrifluoroethylene copolymer resin
(PCTFE), polyvinylidene fluoride resin (PVDF),
Polyvinyl fluoride resin (PVF), ethylene trifluoride ethylene / ethylene copolymer resin (ECTFE), tetrafluoroethylene / hexafluoropropylene copolymer resin (F
EP), and examples of the fluororubber forming the fluororubber layer 3 include vinylidene fluoride / hexafluoropropylene copolymer rubber (VDF-HFP) and vinylidene fluoride / hexafluoropropylene / tetrafluoroethylene copolymer Rubber (VDF-HFP-TF
E) and tetrafluoroethylene / propylene copolymer rubber (TFE-Pr). The thickness of the fluororesin layer or fluororubber layer 3 is preferably 0.1 mm or less, particularly preferably 0.1 to 50 μm.

As a method of preparing the fixing roll of the present invention using the above-mentioned heat conductive silicone rubber composition, for example, a metal roll shaft is placed inside a roll forming die, and then the roll is formed. After placing a tube made of a fluororesin or a fluororubber on the inner wall of the molding die, a thermally conductive silicone rubber composition is pressed into the cavity between the roll shaft and the tube to cure the silicone rubber composition. Method, after placing a metal roll shaft inside the roll forming mold, press-fit the thermally conductive silicone rubber composition, cure this silicone rubber composition,
A method of applying a fluororesin or a fluororubber to the outer peripheral surface of the silicone rubber roll and performing a heat treatment,
In particular, the former method is preferable. At this time, in order to improve the adhesiveness between the roll shaft and the silicone rubber layer and the adhesiveness between the silicone rubber layer and the fluororesin or fluororubber layer, the outer peripheral surface of the roll shaft and the fluororesin or fluororubber tube are used. It is preferable that the inner peripheral surface is previously treated with a primer. As a method of press-fitting the thermally conductive silicone rubber composition into the cavity of the roll shaft and the tube made of fluororesin or fluororubber, for example,
A compression molding machine, a transfer molding machine, and an injection molding machine can be used. Further, when the curing temperature of the thermally conductive silicone rubber composition is extremely low, the curing speed becomes slow,
If the productivity of the fixing roll is significantly reduced, and if the curing temperature is extremely high, wrinkles are formed on the surface of the fixing roll.
The temperature is preferably in the range of 0 ° C.
Preferably it is in the range of 0 ° C. Further, in order to reduce the compression set of the silicone rubber obtained by curing at a relatively low temperature, the silicone rubber is further heated at 150 to 250 ° C.
It is preferable to perform a heat treatment.

In the fixing roll of the present invention, the fluororesin or the fluororubber layer is formed on the outer peripheral surface of the roll shaft via the silicone rubber layer obtained by curing the above-mentioned thermally conductive silicone rubber composition. Despite its excellent thermal conductivity, it has a high repulsive elasticity and excellent copy durability, and thus is suitable as a fixing roll for devices such as electrophotographic copying machines, printers, and facsimile machines.

[0021]

EXAMPLES The thermally conductive silicone rubber composition and the fixing roll of the present invention will be described in more detail with reference to examples. In addition, the viscosity in an Example is a value measured at 25 degreeC. The properties of the silicone rubber were evaluated as follows. [Hardness of Silicone Rubber] The heat conductive silicone rubber composition was heated by a heating press machine at 120 ° C. for 20 minutes to form a silicone rubber, and then heated in a 200 ° C. oven.
Heated for hours. 6m thickness created in this way
The hardness of a silicone rubber with a hardness of m is determined by a spring hardness test specified in JIS K6301 [Vulcanized rubber physical test method].
(Type A) was measured. [Thermal conductivity of silicone rubber]
Showa Denko Sho 12mm thick silicone rubber
The measurement was performed by thertherm QTM (unsteady hot wire method). [Resilience of Silicone Rubber] Silicone rubber JIS K 630 having a thickness of 12 mm prepared by the above method.
It was measured according to the resilience test method specified in 1. [Compression Set of Silicone Rubber] The compression set of the silicone rubber having a thickness of 12 mm produced by the above method was measured in accordance with the compression set test method specified in JIS K6301. The temperature and time of the heat treatment were set at 180 ° C. for 22 hours. [Volume Resistivity of Silicone Rubber] The volume resistivity of the silicone rubber having a thickness of 2 mm prepared by the above method was determined according to JIS.
It was measured according to the volume resistivity test method specified in C 2123 [Test method for silicone rubber compound for electric use].

Further, the fixing roll was prepared as follows. [Production Method of Fixing Roll] After commercially available primer was uniformly applied on the outer peripheral surface of a cylindrical iron roll shaft having a diameter of 10 mm, the primer was sufficiently dried by being left in an oven at 150 ° C. for 30 minutes. In addition, after a commercially available primer was uniformly applied to the inner surface of a tetrafluoroethylene / perfluoroalkyl perfluorovinyl ether copolymer tube whose inner surface was alkali-treated and whose film thickness was 50 μm,
The primer was left to dry at room temperature for 1 hour.
Next, the roll shaft is placed inside the roll forming mold, and the tube is placed on the inner wall of the mold, and the heat conductive silicone rubber is placed in the cavity between the roll shaft and the tube. After injecting the composition,
And cured for 30 minutes to prepare a fluororesin-coated fixing roll having a thickness of 10 mm. Next, this fixing roll was heated in an oven at 200 ° C. for 4 hours.

[Example 1] The viscosity was determined to be 40,000 centipoise by a Ross mixer.

Embedded image 100 parts by weight of a dimethylsiloxane / methylvinylsiloxane copolymer (vinyl group content = 0.5% by weight) having a trimethylsiloxy group at both ends of a molecular chain represented by the formula: and fine alumina powder 180 having an average particle diameter of 3 μm After uniformly mixing the parts by weight, it has a viscosity of 10 centipoise and the formula:

Embedded image 9 parts by weight of a dimethylpolysiloxane (content of silicon-bonded hydrogen atoms = 0.16% by weight) having a dimethylhydrogensiloxy group at both ends of the molecular chain represented by the following formula: The amount of silicon-bonded hydrogen atoms in this dimethylpolysiloxane to be 0.8 mol per 1 mol of vinyl group),
Further, 0.5 parts by weight of a chloroplatinic acid solution in isopropyl alcohol (content of platinum metal = 1% by weight) was uniformly mixed to prepare a thermally conductive silicone rubber composition. The hardness (JIS A) of the silicone rubber obtained by curing the thermally conductive silicone rubber composition is 35, the thermal conductivity is 1.6 × 10 ⁻³ cal / cm · sec · ° C., and the elasticity is resilient. Was 75% and the compression set was 8%. Using this heat conductive silicone rubber composition, a fluororesin-coated fixing roll was prepared. The fixing roll was mounted on an electrophotographic copying machine and 150,000 sheets of A4 size copy paper were continuously copied.
There were no paper wrinkles or paper jams, and all the copied images were clear.

[Comparative Example 1] According to a Ross mixer, the viscosity was 40,000 centipoise.

Embedded image 100 parts by weight of a dimethylsiloxane-methylvinylsiloxane copolymer (vinyl group content = 0.5% by weight) having a trimethylsiloxy group at both ends of a molecular chain represented by the formula: and a finely ground quartz powder having an average particle diameter of 5 μm. After uniformly mixing 140 parts by weight, it has a viscosity of 10 centipoise and has the formula:

Embedded image 7 parts by weight of a dimethyl siloxane / methyl hydrogen siloxane copolymer (content of silicon-bonded hydrogen atoms = 0.16% by weight) having a trimethylsiloxy group at both ends of the molecular chain represented by An amount in which the silicon-bonded hydrogen atoms in the dimethylsiloxane / methylhydrogensiloxane copolymer are 0.65 mol with respect to 1 mol of the vinyl groups in the copolymer), and an isopropyl alcohol solution of chloroplatinic acid (Content of platinum metal = 1% by weight) 0.5 parts by weight were uniformly mixed to prepare a thermally conductive silicone rubber composition. The hardness (JIS A) of the silicone rubber obtained by curing the thermally conductive silicone rubber composition is 35, the thermal conductivity is 1.6 × 10 ⁻³ cal / cm · sec · ° C., and the elasticity is resilient. Was 60% and the compression set was 8%. Using this heat conductive silicone rubber composition, a fluororesin-coated fixing roll was prepared. When this fixing roll was mounted on an electrophotographic copying machine and 150,000 sheets of A4 size copy paper were continuously copied, paper wrinkles and paper jams occurred after the 100,000th sheet.

Comparative Example 2 The viscosity was 40,000 centipoise measured by a Ross mixer.

Embedded image Dimethylpolysiloxane having a dimethylvinylsiloxy group at both ends of the molecular chain represented by the formula (vinyl group content = 0.09)
% By weight) and 180 parts by weight of an alumina fine powder having an average particle diameter of 3 μm are uniformly mixed, and then the mixture has a viscosity of 5 centipoise and the formula:

Embedded image 1 part by weight of a dimethylsiloxane / methylhydrogensiloxane copolymer (content of silicon-bonded hydrogen atoms = 0.45% by weight) represented by the following formula: The amount of silicon-bonded hydrogen atoms in the dimethylsiloxane / methylhydrogensiloxane copolymer is 1.5 mol per 1 mol of the group), and the isopropyl alcohol solution of chloroplatinic acid (content of platinum metal) = 1
0.5% by weight) to prepare a thermally conductive silicone rubber composition. Hardness of silicone rubber obtained by curing this thermally conductive silicone rubber composition
(JIS A) is 35 and the thermal conductivity is 1.6 × 10 ^-3 c
al / cm · sec · ° C., the resilience was 58%, and the compression set was 15%. Using this heat conductive silicone rubber composition, a fluororesin-coated fixing roll was prepared. When this fixing roll was attached to an electrophotographic copying machine and 150,000 sheets of A4 size copy paper were continuously copied, paper wrinkles and paper jams occurred after the 90,000th sheet.

[Comparative Example 3] The viscosity was 40,000 centipoise measured by a Ross mixer.

Embedded image Dimethylvinylsiloxy group-blocked dimethylsiloxane / methylvinylsiloxane copolymer (vinyl group content = 0.12% by weight) represented by the following formula: 100 parts by weight,
And alumina fine powder 180 having an average particle diameter of 3 μm.
After uniformly mixing the parts by weight, it has a viscosity of 6 centipoise and the formula:

Embedded image 2.2 parts by weight of a dimethylsiloxane-methylhydrogensiloxane copolymer (trimethylsiloxy group-blocked dimethylsiloxane / methylhydrogensiloxane copolymer content 0.32% by weight) represented by the following formula: The silicon-bonded hydrogen atoms in the dimethylsiloxane / methylhydrogensiloxane copolymer are each 1 mole of the vinyl group in the vinylsiloxane copolymer.
5 parts by mass) and 0.5 parts by weight of a solution of chloroplatinic acid in isopropyl alcohol (content of platinum metal = 1% by weight) to prepare a thermally conductive silicone rubber composition. The hardness (JIS A) of the silicone rubber obtained by curing the thermally conductive silicone rubber composition is 35.
The thermal conductivity is 1.6 × 10 ⁻³ cal / cm · sec · ° C., the resilience is 62%, and the compression set is 12%.
Met. Using this heat conductive silicone rubber composition, a fluororesin-coated fixing roll was prepared. The fixing roll is mounted on an electrophotographic copying machine, and an A4 size copy paper
When 100,000 sheets were continuously copied, paper wrinkles and paper jams occurred after the 100,000th sheet.

Example 2 The viscosity was found to be 8,000 centipoise by a Ross mixer.

Embedded image 100 parts by weight of a dimethylsiloxane / methylvinylsiloxane copolymer (vinyl group content = 0.3% by weight) having a trimethylsiloxy group at both ends of the molecular chain represented by the formula: Parts, and 8 parts by weight of carbon black (Denka acetylene black manufactured by Denki Kagaku Co., Ltd.) were mixed uniformly,
The centipoise is the formula:

Embedded image 0.65 parts by weight of a dimethylsiloxane-methylhydrogensiloxane copolymer (content of silicon-bonded hydrogen atoms = 0.75% by weight) represented by the following formula: The silicon-bonded hydrogen atoms in this dimethylsiloxane / methylhydrogensiloxane copolymer are 0.5 mole per 1 mole of vinyl groups in the vinylsiloxane copolymer.
Mol) and 1.0 part by weight of a solution of chloroplatinic acid in isopropyl alcohol (content of platinum metal = 1% by weight) to prepare a thermally conductive silicone rubber composition. The hardness (JIS A) of the silicone rubber obtained by curing the thermally conductive silicone rubber composition is 2, the thermal conductivity is 1.0 × 10 ⁻³ cal / cm · sec · ° C., and the elasticity is resilient. Was 35%, the volume resistivity was 1.0 × 10 ⁵ Ω · cm, and the compression set was 8%. Using this heat conductive silicone rubber composition, a fluororesin-coated fixing roll was prepared. When this fixing roll was mounted on a laser beam printer and printed on A4 size copy paper, the printed image was clear.

[Comparative Example 4] The viscosity was 8,000 centipoise measured by a Ross mixer.

Embedded image 100 parts by weight of a dimethylsiloxane-methylvinylsiloxane copolymer (vinyl group content = 0.3% by weight) having a trimethylsiloxy group at both ends of the molecular chain represented by the formula: Parts by weight, and 8 parts by weight of carbon black (Denka acetylene black manufactured by Denki Kagaku) were uniformly mixed, and then,
The centipoise is the formula:

Embedded image 0.6 parts by weight of the dimethylsiloxane / methylhydrogensiloxane copolymer (content of silicon-bonded hydrogen atoms = 0.75% by weight) having a trimethylsiloxy group at both ends of the molecular chain represented by the following formula: The silicon-bonded hydrogen atoms in the dimethylsiloxane / methylhydrogensiloxane copolymer were 0.4 per mole of the vinyl groups in the vinylsiloxane copolymer.
5 mol) and 1.0 part by weight of a solution of chloroplatinic acid in isopropyl alcohol (content of platinum metal = 1% by weight) to prepare a thermally conductive silicone rubber composition. The hardness (JIS A) of the silicone rubber obtained by curing the thermally conductive silicone rubber composition is 2, the thermal conductivity is 1.0 × 10 ⁻³ cal / cm · sec · ° C., and the elasticity is resilient. Is 20% and the volume resistivity is 1.0 × 10 ⁵ Ω · cm
And the compression set was 8%. Using this heat conductive silicone rubber composition, a fluororesin-coated fixing roll was prepared. The fixing roll was mounted on a laser beam printer and printed on A4 size copy paper, but the initial image was unclear.

[0029]

The heat-conductive silicone rubber composition of the present invention comprises the components (A) to (D). In particular, as the component (A), an average of three or more silicon atoms bonded to the side chain of the molecular chain. Since a diorganopolysiloxane having an alkenyl group is used, it has a feature that a silicone rubber having high resilience can be formed in spite of having high thermal conductivity. Further, the fixing roll of the present invention is characterized by having excellent copying durability since such a silicone rubber is used for the member.

[Brief description of the drawings]

FIG. 1 is a sectional view of a fixing roll of the present invention.

[Explanation of symbols]

 1 roll shaft 2 silicone rubber layer 3 fluororesin layer or fluororubber layer

Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G03G 15/20 103 G03G 15/20 103 // (C08K 3/00 3:22 3:08) (72) Inventor Yoshito Shio Chiba 2-2 Chikusa Beach, Hara City Dow Corning Toray R & D Headquarters

Claims (2)

[Claims] (A) 100 parts by weight of a diorganopolysiloxane having an average of three or more silicon-bonded alkenyl groups in one molecular side chain, and (B) an alumina fine particle having an average particle diameter of 0.1 to 50 μm. Powder 50-50
0 parts by weight, (C) an organopolysiloxane having at least two silicon-bonded hydrogen atoms in one molecule. 1 mole of the alkenyl group in the component (A), the silicon-bonded hydrogen atoms in the component are A thermally conductive silicone rubber composition comprising a platinum-based catalyst in an amount of from 0.3 to 1.2 mol｝ and (D) a catalytic amount. 2. A fixing roll in which a fluororesin layer or a fluororubber layer is formed on the outer peripheral surface of a roll shaft with a silicone rubber layer interposed therebetween, wherein the silicone rubber forming the silicone rubber layer is the same as in claim 1. A fixing roll obtained by curing a heat conductive silicone rubber composition.