JPH1010896A - Electrophotographic fixing member and fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic fixing member which is strong to wear, is highly durable, has an excellent release property to toners even under a condition of decreasing the amt. of a release agent, is capable of uniformly fixing unfixed toner images, is high in the smoothness of an image surface after fixing and provides high image quality and a fixing device formed by using the same. SOLUTION: This member is formed by having a surface layer 4 consisting of a heat resistant elastomer dispersed with inorg. fillers treated by a silane coupling agent contg. perfluoroalkyl groups. In this case, the member is used as an elastic heating roll or heating belt, etc., of the fixing device. The heating roll 1 has the constitution obtd. by forming an elastic layer 3 and the surface layer 4 on a hollow arbor 2 and is so arrange to face a pressure roller 11 in such a manner that a nip area is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing member used in a copying apparatus, a printer, and various other image forming apparatuses using an electrophotographic system, and further includes a roller-shaped or belt-shaped elastic member. The present invention relates to a fixing device for fixing a toner image by heat and pressure using a rotating body.

[0002]

2. Description of the Related Art A fixing device used in a copying apparatus, a printer and the like using an electrophotographic system which has been conventionally used is constituted as follows.

A fixing device has two rotating members, for example, as shown in FIG.
As shown in the figure, the heating roll 1 is composed of a pair of rolls of a heating rotator called a heating roll formed in a roll shape and a pressing rotator called a pressure roll formed in a roll shape. The heating roll 1 is made of aluminum, On the surface of a cylindrical hollow core 2 made of iron or the like, fluorine rubber, silicone rubber, polytetrafluoroethylene (PTFE), a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene (P
FA) and a surface layer 4 made of a heat-resistant elastomer or a heat-resistant resin having excellent release properties, such as a fluororesin, and a heating lamp. A heater 21 is provided. On the other hand, the pressure roll 11 covers the surface of a cylindrical hollow metal core 12 made of aluminum, iron or the like with a surface layer 14 made of a heat-resistant elastomer or a heat-resistant resin having the same or a different type as the heating roll. It is constituted by doing. The heating roll and the pressure roll are pressed against each other by a spring or the like. In order to ensure the durability against friction with the toner image support such as paper, an inorganic oxide such as SiO ₂ or carbon is added to the heat-resistant elastomer or heat-resistant resin of the rotating body surface layer of these fixing devices. An inorganic filler such as black is added.

[0004] However, the rotating body surface layer to which these inorganic additives are added is excellent in durability, but is not excellent in releasability from toner. Therefore, in order to ensure the releasability of the surface layer of the rotating body, a releasing agent such as silicone oil is supplied from the outside to the surface of the heated rotating body on the side directly pressed against the unfixed image by the releasing agent applying device 29. In addition, separation and separation are performed by a release agent layer formed between the unfixed image and the surface. In the drawing, 27 indicates an inlet chute, 28 indicates an outlet chute, 31 indicates paper, and 32 indicates a toner image.

However, with respect to supplying a release agent such as silicone oil, the release agent may be paper or OHP at the time of fixing.
Adhering to a toner image support such as a film, and as a result, discomfort due to stickiness when a hand touches the surface of the toner image support, a problem that adhesive tapes do not adhere, or a release agent from the outside. Since a supply device is required, there is a problem that miniaturization and cost reduction of the fixing device are restricted. For this reason, there is a problem that the amount of the release agent supplied to the surface of the heating rotator is reduced or hardly used.

Therefore, as a method for ensuring the releasability without relying on a releasing agent, a fixing member has been proposed in which the surface of the roll has a low surface energy so that the adhesive force between the roll surface and the toner is reduced. For example, in Japanese Patent Publication No. 4-76381, a rubber composition in which an acrylic polymer containing a perfluoroalkyl group is mixed with an organic synthetic rubber is used, and in Japanese Patent Publication No. 8-14739, a surface rubber layer is used. It has been proposed to add a fluorinated surfactant. However, these have the drawback that although their releasability can be maintained for a long period of time, their abrasion resistance is inferior. Japanese Patent Application Laid-Open Nos. 58-16275 and 63-42424 disclose a method of adding carbon fluoride to a fluororesin.
And JP-A-6-102786 propose a method of adding carbon fluoride to a fluororesin or silicone rubber. However, when carbon fluoride is added to the fluororesin, the fluororesin is poor in elasticity and cannot be fixed uniformly, so there is a drawback that the high image quality aptitude is low. It has the drawback of low performance.

For the reasons described above, it is difficult in the prior art to reduce the amount of the release agent in the fixing device or to satisfy all of the maintenance, the offset resistance and the high image quality in a state where the release agent is hardly used. there were. Therefore, even in a situation where the amount of the release agent is newly excellent and the amount of the release agent is reduced, an elastic rotating body for fixing which is excellent in toner releasability and excellent in high image quality aptitude is required.

[0008]

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances in the prior art, and has as its objects the following objects: (1) it is resistant to abrasion and has excellent durability; (3) A fixing member for electrophotography, which is excellent in releasability from toner even in a situation where (3) an unfixed image can be uniformly fixed, and has high smoothness and high image quality on an image surface after fixing. To provide an improved fixing device.

[0009]

The present inventors have conducted a number of experiments and found that the amount of the release agent was reduced, or the surface of the inorganic filler was added to the surface of the rotating body under the condition that it was hardly used. It has been found that the active group and the binder resin of the toner such as polystyrene and polyester react and combine to increase the adhesion between the surface of the rotating body and the toner. Therefore, as a result of further research, the surface of the inorganic filler dispersed in the heat-resistant rubber surface layer of the elastic rotating body was treated with a silane coupling agent containing a perfluoroalkyl group to seal the active groups on the surface of the inorganic filler. In addition to stopping, the surface layer of the rotating body has a low surface energy, has excellent durability without impairing the effect of the filler, and has excellent release properties even in situations where the amount of release agent is small. The inventors have found that a material can be formed, and have completed the present invention.

Therefore, the above object of the present invention is achieved by the following electrophotographic fixing member and fixing device. That is, the electrophotographic fixing member of the present invention is used for a copying apparatus using an electrophotographic method, a printer, and various other image forming apparatuses, and is particularly suitable for a fixing roll or a belt for fixing an image. And having a surface layer made of a heat-resistant elastomer in which an inorganic filler treated with a silane coupling agent containing a perfluoroalkyl group is dispersed.

Further, the fixing device of the present invention has an elastic heating roll or heating belt having at least a surface having heat resistance and releasability, and a pressure roll pressed against the elastic heating roll or heating belt. An unfixed toner image is passed through a support for supporting an unfixed toner image through a nip area formed between an elastic heating roll or a heating belt and a pressure roll, and fixing is performed by heat and pressure. The heating belt has a surface layer made of a heat-resistant elastomer in which an inorganic filler treated with a silane coupling agent containing a perfluoroalkyl group is dispersed.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details will be described below. As the base material of the fixing member, in the case of a roll, a cylindrical hollow core made of a metal such as aluminum or iron can be mentioned, and in the case of a belt, a heat-resistant resin sheet such as a Ni electroformed sheet and a polyimide. And the like.

Examples of the heat-resistant elastomer include fluorine rubber, silicone rubber, and acrylic rubber.
Among them, fluorine rubber and silicone rubber are desirable. Also,
These heat-resistant elastomers can be compounded with various known inorganic and organic additives such as plasticizers, anti-aging agents and general rubber compounding agents (vulcanizing agents, vulcanizing aids, etc.). is there. However, it is necessary to add these additives within a range that does not impair the releasability of the surface of the toner.

An elastic layer may be interposed between the substrate and the surface layer. As the elastic layer, the same or different type of the above-described heat-resistant elastomer is used.

Inorganic fillers to be treated with a silane coupling agent containing a perfluoroalkyl group to be added to the heat-resistant elastomer include SiO ₂ , TiO ₂ , Al
Inorganic oxides such as ₂ O ₃ , MgO, CaO, Fe ₂ O ₃ ,
SiC (silicon carbide), BN (boron nitride), silicate and the like. The average particle size of these inorganic fillers is
It is preferable to set the thickness in the range of 0.1 μm to 8 μm. If the average particle diameter is larger than 8 μm, the possibility of falling off increases.

These inorganic fillers are treated with a silane coupling agent containing a perfluoroalkyl group. Examples of the silane coupling agent containing a perfluoroalkyl group to be used include compounds represented by the following general formula.

Rf— (CH ₂ ) _n —SiX _{3 wherein} Rf is a perfluoroalkyl group (C _m F _{2m + 1} ,
m is an integer of 1 to 30), X: a chlorine atom, a reactive group such as an alkoxy group (—OC _k H _{2k + 1} , k is an integer of 1 to 5),
n: an integer of 2 to 20] The perfluoroalkyl group may have a linear structure or a branched structure, but preferably has a linear structure. Moreover, the releasability improves as the number of carbon atoms of the perfluoroalkyl group increases, and the number of carbon atoms is preferably 7 or more, particularly preferably in the range of 7-20.

The treatment of the inorganic filler with the silane coupling agent is carried out by dissolving the silane coupling agent in an organic solvent and immersing and stirring the inorganic filler in the solution. This treatment may be performed to such an extent that the dispersibility of the inorganic filler in the heat-resistant elastomer is not impaired. As the organic solvent used in the treatment, when the reactive group: X is a chlorine atom, a halogen-containing solvent, a hydrocarbon solvent,
Non-aqueous organic solvents such as ether solvents are preferred, and a plurality of these solvents may be mixed.
Further, when the reactive group is an alkoxy group, it is desirable to carry out the treatment in ethanol containing a small amount of acetic acid and 5 to 50% of water.

The inorganic additive treated as described above contains 0.1% by weight to 5% by weight of the composition constituting the surface layer.
Although it is contained in the range of 0% by weight, it is preferably in the range of 1% by weight to 30% by weight.

The fixing member of the present invention is manufactured, for example, by the following method. That is, the above-mentioned heat-resistant elastomer is dissolved in a solvent, the inorganic filler treated with the silane coupling agent by the above-mentioned method, and additives such as a vulcanizing agent and a vulcanizing aid are added and stirred. The material is immersed in dip coating, or the treated inorganic filler and the above-mentioned heat-resistant elastomer and additives are added to a solvent, mixed and suspended and dispersed, and the base material is spray-coated or the like. Apply and bake. Thereby, a surface layer is formed on the substrate.

The surface layer of the fixing member according to the present invention has a structure in which the inorganic filler treated with the silane coupling agent containing a perfluoroalkyl group is dispersed in the heat-resistant elastomer as described above. While maintaining the durability-improving effect due to the addition of the filler, the releasability is excellent, and the toner does not adhere to the surface. That is, since the active groups on the surface of the inorganic filler are sealed, and the surface of the inorganic filler has a low surface energy, the adhesive force between the exposed inorganic filler surface and the toner is reduced, and the surface of the fixing member is adhered to the surface. It is possible to suppress toner offset. In addition, since the perfluoroalkyl group is chemically bonded to the surface of the inorganic filler via a siloxane bond, it is possible to exhibit releasability over a long period of time.

Next, the fixing device of the present invention will be described. 2 to 4 are schematic configuration diagrams of a fixing device using the above-described fixing member of the present invention. FIG. 2 is a schematic cross-sectional view of a roll-in type fixing device for a full-color copying machine, in which two rolls, a heating roll 1 and a pressure roll 11, face each other and are pressed so as to form a nip area. I have. The heating roll 1 has a structure in which an elastic layer 3 and a surface layer 4 are sequentially provided on the surface of a hollow metal core 2 having a heater 21 provided therein. Further, the pressure roll 11
Has a structure in which an elastic layer 13 and a surface layer 14 are sequentially provided on the surface of a hollow cored bar 12 having a heater 26 provided therein. As described above, the surface layers 4 and 14 of the heating roll and the pressure roll are each made of a heat-resistant elastomer in which an inorganic filler treated with a silane coupling agent containing a perfluoroalkyl group is dispersed. . In this fixing device, the toner image 32
The paper 31 supported by the heating roll 1 and the pressure roll 1
The fixing is carried out by passing through the nip area formed by 1.

3A and 3B show a fixing device incorporating a belt for a full-color copying machine. FIG. 3A is a schematic sectional view, and FIG. 3B is an enlarged sectional view of a heating belt. The heating belt 6 is rotatably supported by a belt driving roll 24 provided with an elastic layer 24A on its surface and belt transport rolls 25,25. The heater 22 is located at a position facing the pressure roll 11.
And a pressure pad 23 are provided, and the heating belt 6 is heated and pressed against the pressure roll 11 to form a nip area. The heating belt is provided with an elastic layer 8 and a surface layer 9 on a heat-resistant sheet 7, and the surface layer has a heat-resistant property in which an inorganic filler treated with a silane coupling agent containing a perfluoroalkyl group is dispersed. It is composed of an elastomer. Also,
The same pressure roll 11 as in FIG. 2 is used. In this fixing device, fixing is performed by passing the paper 31 supporting the toner image 32 through a nip area formed by the heating belt 6 and the pressure roll 11.

FIG. 4 is a schematic cross-sectional view of a roll-in type fixing device for a black-and-white copying machine, in which two rolls of a heating roll 1 and a pressure roll 11 are opposed to each other and pressed to form a nip area. It is provided in. The heating roll 1
A surface layer 4 made of a heat-resistant elastomer in which an inorganic filler treated with a silane coupling agent containing a perfluoroalkyl group is dispersed is provided on the surface of a hollow metal core 2 having a heater 21 provided therein. . The pressure roll 11 has a structure in which an elastic layer 13 and a fluororesin film 15 are sequentially provided on the surface of a hollow metal core 12. In this fixing device, fixing is performed by passing the paper 31 supporting the toner image 32 through a nip area formed by the heating roll 1 and the pressure roll 11.

[0025]

Hereinafter, embodiments of the present invention will be described.
The present invention is not limited to these examples. Example 1 An inorganic filler was subjected to a surface treatment, a built-in fixing device for a full-color copying machine as shown in FIG. 2 was manufactured, and an evaluation test was performed. (Surface Treatment of Inorganic Filler) [2- (Perfluorooctyl) ethyl] trichlorosilane is used as a silane coupling agent containing a perfluoroalkyl group at 10 ⁻² mol / l.
And dissolved in a mixed solvent of n-hexadecane / carbon tetrachloride (volume ratio = 4: 1) at a concentration of 100 parts by weight, and 10 parts by weight of TiO ₂ fine particles as an inorganic filler were added to 100 parts by weight of this solution. Mixing and stirring were performed under an atmosphere for 3 hours. After the completion of the stirring, the TiO ₂ fine particles taken out of the solution were washed with n-hexadecane, then washed with pure water, and dried.

(Preparation of Heating Roll)
An aluminum hollow core 2 coated with silicone rubber having a thickness of 50 mm and a hardness of 50 degrees as an elastic layer 3 is prepared, a primer for silicone rubber is applied in advance, and then a treated inorganic filler (treated TiO ₂ fine particles) ), A fluororubber and a vulcanization aid were mixed in the following proportions and dispersed and dissolved in an organic solvent. The base material was immersed in the obtained coating solution, dip-coated, baked to form a heat-resistant elastomer surface layer 4, and the heating roll 1 was prepared. Treated TiO ₂ fine particles: 15 parts by weight Fluorine rubber: (G-952, manufactured by Daikin Industries, Ltd.) 100 parts by weight of vulcanization agent (triallyl isocyanurate (TAIC) manufactured by 4 parts by weight Daikin Industries, Ltd.) Peroxide (Par Oxide perhexa, 5 parts by weight (manufactured by NOF CORPORATION) (Preparation of pressure roll) As a base material, an aluminum hollow cored bar 12 coated with silicone rubber having a thickness of 1.5 mm and a hardness of 50 degrees as an elastic layer 13 was used. A pressure roller 11 was prepared by preparing a surface layer in the same manner as in the case of the above-mentioned heating roll.

(Evaluation Test) Using the fixing roll thus obtained, a copying machine (A color 635 manufactured by Fuji Xerox Co., Ltd.) was modified and attached to the configuration shown in FIG. 2, and continuous copying was performed. Then, the smoothness of the image after fixing was evaluated by using a gloss meter GM-26D (manufactured by Murakami Color Research Laboratory Co., Ltd.) at an incident light of 75 ° to the sample. The conditions are as shown below. Toner: Cyan toner for A color 635 manufactured by Fuji Xerox Co., Ltd. Toner image: Solid image (20 cm × 5 cm), toner amount = 1 mg / cm ² Paper: Color paper manufactured by Fuji Xerox Co., Ltd. Transfer speed: 100 mm / sec Release agent oil amount: 4 μl As a result, a smooth image was obtained due to the excellent releasability of the fixing rolls (heating rolls and pressure rolls), and a clear image was obtained even after fixing. The color development of the image
The toner was filled when the gloss value exceeded 40, and the fixing temperature was 125 ° C. to 175 ° C. Even when the number of copies exceeded 150,000, no image disturbance, no offset on the fixing roll, and no abrasion were observed.

Example 2 A heating belt was prepared, a belt-integrated fixing device for a full-color copying machine as shown in FIG. 3 was manufactured, and an evaluation test was performed. (Surface Treatment of Inorganic Filler) The treatment was performed in the same manner as in Example 1. (Preparation of Heating Belt) As a substrate, a polyimide sheet 7 coated with a 0.1 mm thick silicone rubber having a hardness of 30 degrees as an elastic layer 8 was prepared. On this base material, a surface layer was formed by the same method as that described in Example 1, and a heating belt 6 was formed. (Preparation of Pressure Roll) A pressure roll 11 was prepared in the same manner as described in Example 1.

(Evaluation Test) Using the heating belt and the pressure roll thus obtained, a copying machine (A color 635 manufactured by Fuji Xerox Co., Ltd.) was modified and attached to the configuration shown in FIG. Continuous copying was performed under the same conditions as in Example 1, and the same evaluation as in Example 1 was performed. As a result, a smooth image was obtained because of the excellent smoothness due to the excellent release property of the belt, and the image could be peeled off even after fixing. The color development of the image was satisfied where the gloss value exceeded 40, and the fixing temperature was 125 ° C. to 170 ° C. Even when the number of copies exceeded 150,000, no image disturbance, offset on the heating belt, and wear were observed.

Example 3 An inorganic filler was subjected to a surface treatment as described below, and a roll-incorporated fixing device for a black-and-white copying machine as shown in FIG. 4 was manufactured and evaluated. (Surface treatment of inorganic filler) 5 to 50% of water was added, and a small amount of acetic acid was added to prepare an ethanol solution whose pH (hydrogen ion concentration) was adjusted to 5.5. After dissolving [2- (perfluorooctyl) ethyl] trimethoxysilane at a concentration of 10 ⁻² mol / l as a silane coupling agent containing a perfluoroalkyl group in this ethanol solution, 100 weight of the obtained solution was obtained. Parts, as an inorganic filler,
Add 10 parts by weight of SiO ₂ fine particles, and add
Mixing and stirring were performed for hours. After the completion of the stirring, the SiO ₂ fine particles taken out of the solution were washed with 1,1,2-trichloro-1,2,2-trifluoroethane, then with pure water, and dried at 150 ° C. in air at 150 ° C. Heated for hours.

(Preparation of Heating Roll) A hollow metal core 2 made of aluminum was prepared as a base material, coated with a primer in advance, and treated with fine particles of SiO ₂ and a fluororubber (trade name: Daiel Latex GLS, Daikin Industries, Ltd.). Made in the following proportions and spray coating,
Baking was performed to form the heat-resistant elastomer surface layer 4, and the heating roll 1 was formed. Treated SiO ₂ fine particles: 10 parts by weight Fluorine rubber paint (Solution A): 100 parts by weight Fluorine rubber paint (Solution B, curing agent): 5 parts by weight (Preparation of pressure roll) Then, a fluororesin film 1 is formed on an aluminum hollow core 12 coated with a silicone rubber having a hardness of 50 degrees as an elastic layer 13.
5 was coated by tuping to prepare a pressure roll 11.

(Evaluation Test) The fixing roll obtained in this manner was modified and mounted in a copying apparatus (Vision 500 manufactured by Fuji Xerox Co., Ltd.) in the configuration shown in FIG. 4, and continuous copying was performed. The releasability of the solid image when the temperature was changed was evaluated. The conditions are as shown below. Toner: Fuji Xerox Co., Ltd., black toner for VIVACE500 Toner image: solid image (20 cm × 5 cm), toner amount = 1 mg / cm ² Paper: Fuji Xerox Co., Ltd. black and white L paper Transport speed: 300 mm / sec Release agent oil amount : None

As a result, a clear image which can be peeled at a wide range of temperatures was obtained due to the excellent releasing property of the heating roll. The releasable fixing temperature was from 155 ° C to 200 ° C. Even when the number of copies exceeded 300,000, no image disturbance, no offset on the fixing roll, and no abrasion were observed.

Comparative Example 1 (Preparation and Evaluation of Fixing Roll)
Fixing rolls (heating roll and pressure roll) were prepared and evaluated in the same manner except that untreated TiO ₂ fine particles were added instead of O ₂ fine particles. as a result,
The fixing temperature at which the gloss value exceeds 40 is from 125 ° C. to 150 ° C.
° C, which was inferior to that of Example 1 from 125 ° C to 175 °. Further, when the number of copies exceeded 100,000, disturbance of the image and offset on the fixing roll were observed.

Comparative Example 2 (Preparation and evaluation of heating belt and pressure roll)
Except that in place of the treated TiO ₂ particles were added untreated TiO ₂ fine particles to prepare a heated belt in the same way. The same evaluation was performed using the same pressure roll as in Example 2. As a result, the fixing temperature at which the gloss value exceeds 40 is from 125 ° C. to 145 ° C.
To 170 ° C. If the number of copies is 1
When the number of sheets exceeded 100,000, image disturbance and offset on the heating belt were observed.

Comparative Example 3 (Preparation and Evaluation of Fixing Roll)
A heating roll was prepared in the same manner except that untreated SiO ₂ fine particles were added instead of O ₂ fine particles. Using the same pressure roll as in Example 3, the evaluation was performed in the same manner. As a result, the fixing temperature at which peeling is possible is from 165 ° C. to 19 ° C.
5 ° C., which was inferior to that of Example 3 from 155 ° C. to 200 ° C. When the number of copies exceeded 150,000, image disturbance and offset on the fixing belt were observed.

[0037]

According to the fixing member for electrophotography of the present invention, since the inorganic filler treated with the silane coupling agent containing a perfluoroalkyl group is dispersed in the heat-resistant elastomer forming the surface layer, the abrasion is reduced. Strong, excellent releasability, and no toner binder polymer adheres to its surface. Therefore, when the fixing member of the present invention is used in an image fixing device such as a copying machine or a printer using an electrophotographic method, the durability and the releasability of the toner in a situation where the amount of the releasing agent is reduced are improved. Since the image quality is excellent, it is possible to improve maintainability, prevent toner offset, and form a clear image. In addition, since the amount of the release agent used is reduced, not only the tackiness of a fixed image formed on a support such as paper or an OHP film and the adhesion to an adhesive tape or the like are improved, but also the size of the fixing device is reduced. And cost reduction are also possible.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a conventional heating roll type fixing device.

FIG. 2 is a schematic cross-sectional view of a fixing device incorporating a roll for a full-color copying machine according to the present invention.

FIG. 3 is a schematic view of a belt-integrated fixing device for a full-color copying machine according to the present invention, wherein (a) is a schematic sectional view,
(B) is an enlarged sectional view of a heating belt.

FIG. 4 is a schematic cross-sectional view of a belt-type fixing device for a black-and-white copying machine of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heating roll, 2 ... Hollow core metal, 3 ... Elastic layer, 4 ... Surface layer, 6 ... Heating belt, 7 ... Heat resistant sheet, 8 ... Elastic layer,
9: surface layer, 11: pressure roll, 12: hollow core metal, 13
... elastic layer, 14: surface layer, 15: fluororesin film, 21: heater, 22: heater, 23: pressure pad, 24: belt drive roll, 24A: elastic layer, 25 ...
Belt transport roll, 26 ... heater, 31 ... paper, 32 ...
Toner image.

Claims (3)

[Claims] 1. An electrophotographic fixing member having a surface layer made of a heat-resistant elastomer in which an inorganic filler treated with a silane coupling agent containing a perfluoroalkyl group is dispersed. 2. An electrophotographic fixing device according to claim 1, comprising an elastic roll or belt having a surface layer made of a heat-resistant elastomer in which an inorganic filler treated with a silane coupling agent containing a perfluoroalkyl group is dispersed. Parts. 3. An elastic heating roll or heating belt having at least a surface having heat resistance and releasability, and a pressure roll pressed against said elastic heating roll or heating belt. In a fixing device that passes a support for supporting an unfixed toner image through a nip area formed between the pressure roller and a fixing roller by heat and pressure, at least an elastic heating roll or a heating belt has a perfluoroalkyl group. A fixing device having a surface layer made of a heat-resistant elastomer in which an inorganic filler treated with a silane coupling agent is dispersed.