JP5240546B2 - Fixing rotator, fixing device, image forming apparatus, and fixing rotator manufacturing method - Google Patents

Description

The present invention, for example, a manufacturing method of the electrostatic transfer process by you fixing the toner image transferred onto the recording medium constant wear rotor and a fixing device and an image forming apparatus and the fixing rotary member, more particularly to the improvement of thermal conductivity It is.

  In electrophotographic copying machines and printers aiming at high image quality, especially in devices that perform output by color electrophotography, the fixing member for fixing the toner image transferred to the recording medium ensures flexible adhesion to the toner, heat resistance For this reason, silicone rubber is often used. These heat-resistant rubber materials have low thermal conductivity, and become a heat resistance layer when transferring heat from a heat source to the recording medium. In color images, a soft rubber layer is particularly important for improving image quality. However, since the heat capacity is large and the thermal resistance is high, the rise time is delayed. In addition, even in the case of a high-speed machine, the heat supply is not in time. Therefore, as shown in Patent Document 1 and Patent Document 2, attempts have been made to improve thermal conductivity using a filler.

In the fixing member disclosed in Patent Document 1, 20-40% by weight of carbon fiber having a density of 2.20 g / cm 3 or more is contained in silicone rubber so as to increase the thermal conductivity of the silicone rubber layer. In addition, the fixing member disclosed in Patent Document 2 is a three-dimensional network-like molded body made of a silicone rubber foam blended with a heat conductive filler to form a continuous heat flow path, and silicone is formed in the pores. An elastic body having a lower thermal conductivity than rubber is occupied to increase the thermal conductivity.
JP 2005-292218 A JP 2006-133576 A

However, in the techniques disclosed in Patent Document 1 and Patent Document 2, it is impossible to reduce the heat capacity by reducing the density of the fixing member, and development of a fixing member having high thermal conductivity while reducing the density to reduce the heat capacity. The rise time could not be shortened.
There are two reasons for this.
1. In order to reduce the density, when the expansion ratio (the volume Vs in the absence of bubbles is used as the denominator and the sum of the bubbles volume Vf and Vs is used as the numerator) is increased, the thermal conductivity rapidly decreases. This occurs when the thermal conductivity of the original material does not change. (For example, see Eucken's formula in the thermophysical handbook Yokendo C.2 p.179)
2. Similarly, when the expansion ratio is increased, the wall surface becomes relatively thin and the strength decreases.
Due to these two problems, it has been difficult to develop a member having low heat capacity (low density), high thermal conductivity, and heat resistance, with a fixing member that is repeatedly deformed in a high temperature environment.

This invention is to solve such problems, improves the thermal conductivity rises quickly Ru can be enhanced responsiveness to temperature control constant wear rotor and a fixing device and an image forming apparatus and rotated for fixing It aims at providing the manufacturing method of a body .

The fixing rotator according to the present invention is a fixing rotator to which a pressure member is pressed to form a nip portion in which the recording medium is conveyed in a fixing device for fixing unfixed toner on the recording medium. A metal roller having a built-in heat source, and a silicone rubber layer provided on the outer surface of the metal roller, the silicone rubber layer being distributed throughout the thickness direction of the carbon fiber and the silicone rubber layer. a plurality of first holes, a number of the distributed throughout the thickness direction of the silicone rubber layer to have a large volume than the first holes adjacent cavity of the plurality of first It has a second air holes, and a respective said plurality of second holes, and characterized in that a plurality of first holes located next to the second holes are connected to each other To do.

  The carbon fiber is preferably pitch-based carbon fiber.

  The expansion ratio of the silicone rubber layer is preferably 1.5 or more and 3.0 or less.

  Furthermore, the metal roller has a thickness of 0.4 mm to 0.5 mm, and a plurality of circumferential convex reinforcements are integrally formed on the inner surface.

  Moreover, it has the layer which consists of a fluorine-type polymer of the outer surface of the said silicone rubber layer, It is characterized by the above-mentioned.

  As for the surface roughness of the layer made of this fluorine-based polymer, it is desirable that the ten-point average height Rz is 5 μm or less.

  A fixing device according to the present invention includes any one of the fixing rotators described above and a pressure member that is in pressure contact with the fixing rotator.

In the fixing device, the quotient obtained by dividing the pressure F (N) applied to the fixing rotator by the area S (cm ² ) of the contact portion in pressure contact with the fixing rotator is 4.9 (N / cm ² ) or more. 39.2 (N / cm ² ) or less.

  An image forming apparatus according to the present invention includes the fixing device and an electrophotographic image forming unit. The image forming unit forms a toner image on a recording medium, and the toner image formed on the recording medium is fixed by the fixing device. It is characterized by making it.

  The method for producing a heating member of the present invention includes a step of foaming an unvulcanized addition-type silicone rubber containing carbon fibers and first pre-expanded particles by containing a foaming agent or foamed particles, and an unvulcanized addition-type silicone. And a second vulcanization step after first vulcanizing the rubber.

The present invention provides a silicone rubber layer that conducts heat, including carbon fibers , a plurality of first holes, and a plurality of second holes having a volume larger than that of the first holes. is because I was constructed in a structure in communication with the first holes located around the carbon fiber becomes a path for heat conduction, since the first of the holes smaller has a multi I構 granulation just large The temperature rise can be accelerated because the heat capacity is lower than that with holes. Further, by reinforcing the silicone rubber with carbon fibers, compression set can be reduced even if there are large second holes.

  Moreover, by using pitch-based carbon fibers as carbon fibers, the thermal conductivity can be increased to 500 W / mK or more, and the thermal conductivity is higher by one digit or more than PAN-based carbon fibers. Can be secured.

  Furthermore, when the expansion ratio of the silicone rubber layer is 1.5 or more and 3.0 or less, the low heat capacity and strength are satisfied, and a sufficient fixing operation is possible. That is, when the expansion ratio is 1.5 times or less, the heat capacity is large, so that the thickness for enlarging the nip cannot be secured. When the expansion ratio is 4.0 times, the wall surface of the secondary structure becomes extremely thin. The strength decreases and the compression set increases, but such adverse effects can be prevented.

  In addition, the metal roller has a thickness of 0.4 mm to 0.5 mm, and a plurality of circumferential convex reinforcements are integrally formed on the inner surface. The strength can be ensured, and a fast start-up fixing device can be obtained.

  Moreover, by having the layer which consists of a fluorine-type polymer of the outer surface of a silicone rubber layer, mold release property and durability can be improved.

  Furthermore, by setting the surface roughness of the layer made of the fluoropolymer to a 10-point average height Rz of 5 μm or less, it is possible to prevent toner from adhering and improve durability.

  In addition, the fixing device having the fixing rotator of the present invention and the pressure member pressed against the fixing rotator is heated efficiently because of uniform heat transfer, quick start-up, and high film strength. In addition, the durability can be improved.

In the fixing device, the quotient obtained by dividing the pressure F (N) applied to the fixing rotator by the area S (cm ² ) of the contact portion in pressure contact with the fixing rotator is 4.9 (N / cm ² ) or more. By setting it to 39.2 (N / cm ² ) or less, fixing can be performed with an appropriate pressure, and image fixing properties can be improved.

  An image forming apparatus including the fixing device and an electrophotographic image forming unit can increase energy efficiency and save energy.

According to the method for manufacturing a fixing rotor of the present invention, an unvulcanized addition-type silicone rubber containing carbon fibers and first pre-expanded particles is foamed by containing a foaming agent or foamed particles, and the unvulcanized addition-type silicone is produced. By first vulcanizing the rubber and then secondarily vulcanizing, the carbon fibers oriented by the first foamed particles are compressed, improving the contact efficiency between the carbon fibers, and the thermal resistance between the carbon fibers Can be made very small, and the uniform orientation improves the strength and reduces the compression set.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present invention. The image forming apparatus 1 includes a photoreceptor 2, a charging device 3, a writing device 4, a developing device 5, a transfer device 6, a cleaning device 7, and a fixing device 8. The image forming apparatus 1 uniformly charges the surface of the photoreceptor 2 with the charging device 3, and scans the charged photoreceptor 2 with light according to image information formed by the writing device 4 to form an electrostatic latent image. The toner image is formed and visualized by supplying toner to the formed electrostatic latent image by the developing device 5 to form a toner image. The toner image formed on the photoconductor 2 is transferred to a recording medium by the transfer device 6, and the toner remaining on the photoconductor 2 is removed by the cleaning device 7 to prepare for the next image formation. The recording medium to which the toner image is transferred is sent to the fixing device 8.

  The fixing device 8 includes a fixing roller 9 and a pressure roller 10 as shown in the cross-sectional view of FIG. The fixing roller 9 includes a metal roller 12 having a heater 11 as a heat source therein, a silicone rubber layer 13 provided on the outer surface of the metal roller 12, and a PFA layer 14 provided on the surface of the silicone rubber layer 13. . The pressure roller 10 is pressed against the fixing roller 9 by the pressure mechanism 15, and the recording medium 17 onto which the toner image 16 is transferred is fixed by heat and pressure when passing through the nip portion between the fixing roller 9 and the pressure roller 10.

  A cross section of the surface portion of the fixing roller 9 is shown in FIG. 3, and an enlarged cross section of the silicone rubber layer 13 is shown in FIG. The silicone rubber layer 13 includes a silicone rubber containing carbon fibers 18, a substructure 20 of a small volume single bubble 19, and a large volume single bubble 21. Here, the single bubble means a bubble that is not connected to the adjacent bubble (hole). As shown in FIG. 5, the continuous bubble refers to a single bubble that is connected to an adjacent bubble so that the gas inside can flow during deformation.

FIG. 3 schematically shows a state in which the heat from the heater 11 flows through the secondary rubber 20 portion of the silicone rubber containing the carbon fiber 18 of the silicone rubber layer 13 and the small volume single bubble 19. Heat flow 22 is shown. FIG. 6 shows details of the heat flow 22 flowing through the substructure 20 portion. In order to improve the thermal conductivity of the silicone rubber layer 13, it is important to reduce the orientation of the carbon fibers 18 and the thermal resistance. As shown in FIG. 4 and FIG. 6, the high thermal conductivity carbon fiber 18 is oriented in the wall portion in parallel with the bubbles 19 and 21, so that high thermal conductivity can be obtained. In particular, when a foaming agent is used, since the pressure at the time of foaming increases the number of contact portions between the carbon fibers 18, it is possible to make the thermal resistance very small. As the carbon fiber 18, pitch type Nippon Graphite Fiber Co., Ltd. product name: carbon fiber milled product number: XN-100-05M (50 microns) is optimal. The thermal conductivity of XN-100-05M (50 microns) is 500 W / mK. On the other hand, the thermal conductivity of the PAN system is 50 W / mK at the maximum. Furthermore, it is also useful to classify pitch-based carbon fibers with a sieve, an air current, etc., and use short ones.
Moreover, the carbon fiber 18 has good adhesiveness with silicone rubber, and can increase the tensile strength of the wall surface of the foamed silicone rubber layer 13. Higher thermal conductivity can be achieved through an appropriate process.
Furthermore, it becomes possible to lower a heat capacity by taking a secondary structure, and a material with a lower heat capacity can be obtained.

When the silicone rubber layer 13 is produced, an unvulcanized addition type silicone rubber containing a foaming agent or expanded particles in an unvulcanized addition type silicone rubber including the carbon fiber 18 and the first already expanded particles is previously added. Set a PFA tube with an adhesive layer on the inner surface and a metal core with a convex reinforcement (called a rib) on the inner surface of 0.5 mm inside, and mix with a curing agent between them. Inject between cores. Next, it is foamed by primary heating and fixed by secondary heating.
Alternatively, a silicone non-crosslinked liquid prepared in the same manner can be applied to a roller and crosslinked to prepare a fluororesin coat layer, or it can be covered with a fluororesin tube.

  As the fluororesin that forms the PFA layer 14 of the fixing roller 9, a resin having a relatively low melting point (preferably 250 to 300 ° C.) having a good melt film forming property by firing is preferably selected. Specific examples include fine powders of low molecular weight polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). It is done. As the low molecular weight polytetrafluoroethylene (PTFE) powder, Lubron L-5, L-2 (Daikin Industries), MP1100, 1200, 1300, TLP-10F-1 (Mitsui DuPont Fluorochemical) are known. As the tetrafluoroethylene-hexafluoropropylene copolymer (FEP) powder, 532-8000 (DuPont) is known. As the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), MP-10, MP102, (Mitsui DuPont Fluorochemical) are known. In particular, MP103, MP300 (Mitsui Dupont Fluorochemical), AC-5600, AC5539 (Daikin Industries) and the like are suitable as those having a low MFR (melt flow rate) and low fluidity.

  Examples of the foaming agent include azobisisobutyronitrile (AIBN) and the like, and examples of the foamed particles include Matsumoto Yuka Pharmaceutical's F-30, F-30VS, F-46, F-50D, F-55D, and the like. is there. Further, as the already expanded particles, Matsumoto Yushi Seiyaku's 100CA, 80CA, F-80DE, F-30E, F-50E, F-80SDE and the like are available.

The carbon fibers 18 include PAN (polyacrylonitrile) carbon fibers made from synthetic acrylic long fibers and pitch carbon fibers made from coal tar and petroleum pitch.
PAN-based carbon fiber is obtained by carbonizing a PAN precursor (polyacrylonitrile fiber) and has properties of high strength and high elastic modulus.
Pitch-based carbon fibers are obtained by carbonizing pitch precursors (pitch fibers obtained from coal tar or heavy petroleum oil as a raw material). Under various manufacturing conditions, low-modulus to ultra-high modulus / high strength A wide range of properties can be obtained. Ultra-high modulus products have excellent thermal conductivity and conductivity characteristics, as well as high rigidity applications.

  Next, the present invention will be described in detail with reference to examples.

Example 1
A powder of F-80SDE (diameter of about 30 μm) and XN-100-05M (length of about 50 μm) dispersed in uncured addition-type liquid silicone is prepared. Next, F-50D is added as expanded particles to produce an uncured addition-type liquid silicone. Further, it is applied to the aluminum metal roller 12 through a primer. This coating layer is formed by foaming to a thickness of 2 mm and is primarily cured. At this time, F-50D had a size of 150 μm to 200 μm. Further, secondary curing was performed, and a PFA resin tube was bonded to the outside to produce an outer diameter of 40 mm. This was set in a fixing unit of a copying machine MF4570 manufactured by Ricoh Co., Ltd., and the temperature rise time (seconds) up to 160 ° C. with a 1000 W halogen heater was measured. The temperature was measured by providing a thermocouple in the upper part of the fixing rotator. When the PFA resin layer is made of a material having a model number of HP-Plus 950HP manufactured by Mitsui / DuPont Fluorochemical Co., Ltd., the spherulite is reduced and the surface roughness is improved. The thickness of the metal roller 12 is 0.4 mm with a rib. The formulation is parts by weight with respect to the silicone rubber 100. The amount of F-50D is used for adjusting the expansion ratio, and is indicated by the overall measured expansion ratio by the Archimedes method. Basically, the larger the amount of F-50D, the higher the expansion ratio.

  Comparison between Example A to Example C in which XN-100-05M was used as the carbon fiber 18 and the expansion ratio was changed, and Comparative Example A having no secondary structure 20 as shown in FIG. Table 1 below shows the temperature rise time (sec) and compression set (%) of Example B and Comparative Example C using PAN as carbon fiber.

  As shown in Table 1, Example A, Example B, and Example C start up within 30 seconds. On the other hand, since the contact efficiency of the carbon fiber is low in the comparative example A, it is considered that the rise in the comparative example C is slow because the thermal conductivity of the carbon fiber is low. In Comparative Example B, the compression set was large, and deformation of the heating roller was observed by heating and pressing at 160 ° C. for 100 hours.

(Example 2)
A powder of F-80SDE (diameter of about 30 μm) and XN-100-05M (length of about 50 μm) dispersed in addition-type liquid silicone is prepared. Next, as an already expanded particle, F-80DE (diameter of about 100 μm) is added to produce an uncured addition type liquid silicone. A powder-dispersed silicone layer is formed to a thickness of 2 mm through a primer on an aluminum metal roller 12 and is primarily cured. Further, secondary curing was performed, and a PFA resin tube was bonded to the outside to produce an outer diameter of 40 mm. This was set in a fixing unit of a copying machine MF4570 manufactured by Ricoh Co., Ltd., and the temperature rise time (seconds) up to 160 ° C. with a 1000 W halogen heater was measured. The temperature was measured by providing a thermocouple in the upper part of the fixing rotator. The blending was performed in parts by weight, but F-80D was added as a bubble up to the specified expansion ratio. When the PFA resin layer is made of a material having a model number of HP-Plus 950HP manufactured by Mitsui DuPont Fluorochemical Co., Ltd., the spherulite is reduced and the surface roughness is improved. The thickness of the metal roller 12 is 0.4 mm with a rib.

  Example D to Example F in which the expansion ratio was changed using XN-100-05M as the carbon fiber 18, Comparative Example D having no secondary structure 20, Comparative Example E having a higher expansion ratio, and carbon fiber Table 2 below shows the temperature rise time (sec) and compression set (%) of Comparative Example F using a PAN system.

  As shown in Table 2, in Example D to Example F, it rises within 30 seconds. Further, when Comparative Example D and Example E are compared, Example E has half the rise time of Comparative Example D. In Comparative Example E, the compression set is large, and the heating roller is deformed by heating and pressing at 160 ° C. for 100 hours. In Comparative Example F, the rise time is very slow.

(Example 3)
Table 3 below shows the temperature rise time (sec) and compression set (%) of Example G and Comparative Examples G to J, in which the fixing member of Example B was produced by changing the thickness of the cored bar.

  As shown in Table 3, in the case of Example G in which the thickness of the metal roller 12 is 0.5 mm, the rise time is 20 seconds or less, and Comparative Examples G to Comparative Example in which the thickness of the metal roller 12 is 0.6 mm or more. I got up in a short time compared to I. Further, in Comparative Example J in which the thickness of the metal roller 12 was 0.3 mm, destruction occurred during rotation.

Example 4
The surface roughness of the metal roller 12 of Example B was changed and mounted on a fixing unit of MF4570 manufactured by Ricoh Co., Ltd., and 10000 sheets were passed through a black solid image of imagio MP C4500 manufactured by Ricoh Co., Ltd. The results of examining the toner adhesion amount and the paper wrapping are shown in Table 4 below.

  As shown in Table 4, if the surface roughness (ten-point average roughness: JIS B0601-1994) Rz of the metal roller 12 is 5 μm or less, there is no toner adhesion and paper wrapping, and the surface roughness is 7 μm. With 6530 sheets, jams occurred frequently, so the experiment was canceled.

(Example 5)
An unfixed image created with IPSIO Color 8100 manufactured by Ricoh Co., Ltd. was tested. Since the toner of the IPSIO Color 8100 has insufficient releasability, an oil application member impregnated with silicon oil is additionally applied to the surface of the fixing roller 9. Through this IPSIO Color 8100, 10,000 black solid images were passed, and the toner adhesion state on the roller surface was observed. No significant adhesion was observed. There was no change from the normal one. When the coating member was removed, the toner adhered to the fixing roller 9 on 60000 sheets.

(Example 6)
A fixing roller 9 of Example B having a surface roughness Rz of 2 μm or less was produced. A fixing tester using a fixing unit of MF4570 was manufactured, and the pressure applied to the unfixed image of imagio MP C4500 was changed, and the toner adhesion amount on the roller surface and paper wrapping when the fixing roller 9 was used to pass the paper Table 5 below shows the results of examining the fixability.

As shown in Table 5, when the applied pressure is 2.9 (N / cm ² ) or less, the fixability is very poor, and when the applied pressure is 19.6 (N / cm ² ) or more, toner adhesion to the fixing roller 9 is observed. It was. Further, the paper wrapping is caused by the further deterioration of the toner adhesion state and the wrapping. Further, when the applied pressure is 39.2 (N / cm ² ) or less, no wrapping of paper is observed. In addition, as a result of rubbing the solid cloth on the solid image after fixing and having the toner on the cloth remarkably determined as a fixing failure, the fixing failure was found when the applied pressure was 2.9 (N / cm ² ). . As a result, the applied pressure is desirably 39.2 (N / cm ² ) or less and 4.9 (N / cm ² ) or more.

(Example 7)
An example in which the heating member of the present invention is applied to a belt-type fixing device is shown in FIG. In the fixing device shown in FIG. 8, a fixing belt 33 is wound around a heating roller 31 and a fixing roller 32 having a heater 30 inside, and is held in a tensioned state by a tension spring 34. The pressure roller 36 pressed by the fixing belt 33 and the pressure spring 35 forms a nip portion, and the recording medium 17 on which the toner 16 guided by the inlet guide plate 37 is placed is introduced into the nip portion. The fixing belt 33 is temperature-controlled by temperature measurement by a temperature sensor 38 such as a thermistor. As the fixing belt 33, a heat-resistant polymer material or a metal belt is used as a base.

  As a substrate constituting the fixing belt 33, for example, a polyimide belt having a thickness of 50 μm is used, and a powder-dispersed silicone layer is formed with a thickness of 400 μm through a primer and is primarily cured. Further, secondary curing was performed, and a PFA resin tube was bonded to the outside. This was set in a fixing unit of a printer IPSiO-CX8800 manufactured by Ricoh Co., Ltd., and the temperature rise time (seconds) up to 160 ° C. with a 1000 W halogen heater was measured. The temperature was measured using a thermistor. The blending was carried out in parts by weight, but F-80D was added as bubbles up to the specified expansion ratio. When the PFA resin layer is made of a material having a model number of HP-Plus 950HP manufactured by Mitsui / DuPont Fluorochemical Co., Ltd., the spherulite is reduced and the surface roughness is improved. The thickness of the heating roller 31 is 0.4 mm with a rib.

  Example H to Example J in which the expansion ratio was changed using XN-100-05M as the carbon fiber, Comparative Example K having no secondary structure 20 as shown in FIG. 7, and Comparative Example in which the expansion ratio was increased Table 6 below shows the temperature rise time (sec) and compression set (%) of Comparative Example M using PAN as L and carbon fiber.

  As shown in Table 6, in Example H to Example J, the operation was started within 20 seconds. Further, when Comparative Example K and Example I are compared, Example I has a rise time 1/5 that of Comparative Example K. In Comparative Example L, it is considered that the rise is delayed due to a decrease in thermal conductivity due to poor contact between fillers. Furthermore, in Comparative Example M, the rise time is very slow.

1 is a schematic configuration diagram of an image forming apparatus of the present invention. FIG. 2 is a cross-sectional view illustrating a configuration of a fixing device. FIG. 3 is a cross-sectional view illustrating a configuration of a surface portion of a fixing roller. FIG. 3 is an enlarged cross-sectional view illustrating a configuration of a silicone rubber layer of a fixing roller. It is an expanded sectional view which shows the secondary structure which has a continuous bubble of a silicone rubber layer. It is an expanded sectional view which shows the heat flow in the secondary structure which has the single bubble of a silicone rubber layer. It is an expanded sectional view of the silicone rubber layer which does not have a silicone rubber containing carbon fiber and the substructure of a single bubble. It is a block diagram of a belt-type fixing device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1; Image forming apparatus, 2; Photoconductor, 3; Charging apparatus, 4; Writing apparatus, 5; Developing apparatus,
6; transfer device, 7; cleaning device, 8; fixing device, 9; fixing roller,
10; pressure roller, 11; heater, 12; metal roller, 13; silicone rubber layer,
14; PFA layer, 15; pressure mechanism, 16; toner image, 17; recording medium,
18; carbon fiber, 19; single foam, 20; substructure, 21; single foam, 22; heat flow.

Claims (10)

A fixing rotating body in which a pressure member is pressed to form a nip portion in which the recording medium is conveyed in a fixing device for fixing unfixed toner on the recording medium,
A metal roller having a built-in heat source, and a silicone rubber layer provided on the outer surface of the metal roller,
The silicone rubber layer, carbon fibers, a number of first distributed throughout the thickness direction of the silicone rubber layer and the pores of the first cavity of the plurality of first have a large volume from A plurality of second holes distributed throughout the thickness direction of the silicone rubber layer so as to be adjacent to the holes,
Fixing rotatable member, characterized in that the each of the plurality of second holes, and a plurality of first holes located next to the second holes are connected to each other.   The fixing rotating body according to claim 1, wherein the carbon fibers are pitch-based carbon fibers.   The fixing rotating body according to claim 1 or 2, wherein the expansion ratio of the silicone rubber layer is 1.5 or more and 3.0 or less.   4. The metal roller according to claim 1, wherein the metal roller has a thickness of 0.4 mm to 0.5 mm, and a plurality of circumferential protrusion reinforcements are integrally formed on the inner surface. Rotor for fixing.   5. The fixing rotator according to claim 1, further comprising a layer made of a fluorine polymer on an outer surface of the silicone rubber layer.   6. The fixing rotator according to claim 5, wherein the ten-point average height Rz of the surface of the layer made of the fluoropolymer is 5 [mu] m or less.   7. A fixing device comprising: the fixing rotator according to claim 1; and a pressure member that presses against the fixing rotator. 8. The fixing device according to claim 7, wherein a quotient obtained by dividing a pressing force F (N) applied to the fixing rotator by an area S (cm ² ) of a contact portion in pressure contact with the fixing rotator is 4.9 (N / cm ² ) or more and 39.2 (N / cm ² ) or less.   9. A fixing device according to claim 7 and an electrophotographic image forming unit, wherein the image forming unit forms a toner image on a recording medium, and the toner image formed on the recording medium is fixed by the fixing device. An image forming apparatus. A method for manufacturing a fixing rotor according to claim 1,
The step of producing the silicone rubber layer includes a step of foaming an unvulcanized addition-type silicone rubber containing carbon fibers and first pre-expanded particles by containing a foaming agent or foamed particles, and an unvulcanized addition-type silicone. And a second vulcanization step after first vulcanizing the rubber.

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