JP7278796B2 - Roller and fixing device - Google Patents

Description

The present invention relates to a roller suitable for use in a fixing device mounted in an image forming apparatus such as an electrophotographic copier or an electrophotographic printer, and a fixing device having the roller.

2. Description of the Related Art A film heating type device is known as a fixing device mounted on an electrophotographic copier or printer. This type of fixing device has a cylindrical film, a plate-like heater that heats the film while being in contact with the inner peripheral surface of the film, and a pressure roller that forms a nip portion together with the heater via the film. are doing. A recording material carrying an unfixed toner image is heated while being nipped and conveyed in the nip portion, whereby the toner image is fixed on the recording material.

It is known that when small-size recording materials are printed continuously at the same print interval as large-size recording materials in copiers and printers, the temperature of the non-passage area of the nip portion of the fixing device, through which the small-size recording materials do not pass, rises excessively. ing. If the temperature of the non-passing region of the nip portion rises excessively, the film heated by the heater and the holder supporting the heater will be damaged.

In order to suppress excessive temperature rise in the non-passing area of the nip portion, the heat of the non-passing area of the nip portion is transferred to the passing area by increasing the thermal conductivity of the pressure roller in the direction perpendicular to the conveying direction of the recording material. , a configuration for lowering the temperature of the non-passing area has been proposed. Patent Document 1 proposes a pressure roller having an elastic layer containing a thermally conductive filler such as pitch-based carbon fiber on the outer periphery of a solid rubber elastic layer. Patent Document 2 proposes a pressure roller in which an adhesive layer between an elastic layer and a release layer contains a thermally conductive filler.

JP-A-2009-31772 JP 2009-103882 A

As the processing speed (process speed) of the printer increases, the temperature of the non-passing area of the nip portion of the fixing device tends to increase, and further suppression of the excessive temperature rise of the non-passing area is required. This is because the time required for the recording material to pass through the nip portion becomes shorter as the speed increases, so the fixing temperature required to heat and fix the toner image onto the recording material must be increased. In addition, the time during which the recording material does not intervene in the nip portion during continuous printing (hereinafter referred to as the time between recording materials) decreases as the speed of the printer increases. Because it becomes difficult.

Therefore, in order to further suppress the excessive temperature rise in the non-passing area of the nip portion, it is conceivable to increase the thermal conductivity of the pressure roller in the direction orthogonal to the recording material conveying direction. As one of them, a configuration in which the fiber length of a thermally conductive filler such as carbon fiber is lengthened is conceivable.

However, when the fiber length of the filler is lengthened, the fibers become entangled with each other, thereby exerting a reinforcing effect, and the hardness of the pressure roller may be remarkably increased. As a result, there has been a problem that the width of the nip portion in the recording material conveying direction is reduced, and the fixing performance is degraded.

SUMMARY OF THE INVENTION An object of the present invention is to provide a roller capable of suppressing an increase in hardness even when a fibrous thermally conductive filler is used, and a fixing device having the roller.

One aspect of the present invention is a roller used in a fixing device that fixes an image formed on a recording material to the recording material, the roller having a core metal and an elastic layer provided around the core metal. In the elastic layer, filler bundles in which a plurality of fiber-like fillers are bundled are dispersed, and the thickness of the filler bundles is smaller than the thickness of the elastic layer and is included in the filler bundles. The orientation of the plurality of fillers is uniform, the filler bundle is oriented in a direction along the axial direction of the roller, and the filler bundle is a filler bundle having an average fiber length of 2 mm or less. characterized by being

ADVANTAGE OF THE INVENTION According to this invention, even if it uses a fibrous thermally conductive filler, it can suppress that hardness becomes high.

FIG. 2 is a cross-sectional view showing a schematic configuration of a fixing device; A view of the fixing device when viewed from the upstream side in the recording material conveying direction Perspective view and cross-sectional view of pressure roller A photograph showing a section cut in the thickness direction of the heat conductive layer of the pressure roller FIG. 2 is a perspective view of a fixing device showing a state in which a small-sized recording material is being conveyed in a nip portion; Cross-sectional view of a thermally conductive layer containing short fillers and a thermally conductive layer containing long fillers (a) is a cross-sectional view of one filler, (b) is a cross-sectional view of three fillers gathered in a bundle, (c) is a cross-sectional view of eight fillers gathered in a bundle, (d) Cross-sectional view of six fillers gathered in a bundle Schematic showing the orientation of unbunched fillers dispersed in a thermally conductive layer Schematic showing the orientation of bundled fillers dispersed in a thermally conductive layer FIG. 4 is a diagram showing hardness measurement positions of the pressure roller in a direction orthogonal to the recording material conveying direction; FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. Although the preferred embodiment of the present invention is an example of the best embodiment of the present invention, the present invention is not limited to the following embodiments, and various other configurations are possible within the scope of the idea of the present invention. can be replaced with

(1) Image forming apparatus 100
An image forming apparatus according to this embodiment will be described with reference to FIG. FIG. 11 is a sectional view showing a schematic configuration of an image forming apparatus (full-color printer in this embodiment) 100 using electrophotographic recording technology. The process speed of the image forming apparatus 100 shown in this embodiment is 180 mm/s.

In the image forming apparatus 100, the image forming section 10 that forms an image on the recording material P using toner has four image forming stations SY, SM, SC, and SK for yellow, magenta, cyan, and black. Each image forming station has a photosensitive drum 1 as an image carrier, a charging member 2, a laser scanner 3, a developing device 4, a transfer member 5, and a cleaner 6 for cleaning the outer peripheral surface of the photosensitive drum. are doing.

The image forming unit 10 further includes a belt 7 that carries and conveys the toner image transferred from each photosensitive drum by a transfer member, and a secondary transfer member 8 that transfers the toner image from the belt to the recording material P. there is Since the operation of the image forming section 10 described above is well known, detailed description thereof will be omitted.

The recording material P accommodated in the cassette 20 in the apparatus main body 100A is supplied to the roller 31 sheet by sheet as the roller 30 rotates. The recording material P is conveyed to the secondary transfer nip formed by the belt 7 and the secondary transfer member 8 by the rotation of the roller 31, and the toner image is transferred onto the recording material P at the secondary transfer nip. A recording material P bearing an unfixed toner image is sent to a fixing device 50 as a fixing unit, and the toner image is heat-fixed onto the recording material by the fixing device. The recording material P coming out of the fixing device 50 is discharged to the tray 40 by the rotation of the roller 32 .

(2) Fixing device 50
Next, the fixing device 50 will be described with reference to FIGS. 1 and 2. FIG. FIG. 1 is a sectional view showing a schematic configuration of the fixing device 50. As shown in FIG. FIG. 2 is a diagram of the fixing device 50 viewed from the upstream side in the recording material conveying direction Z. As shown in FIG. In FIG. 2, the central portion of the fixing device 50 in the direction X orthogonal to the recording material conveying direction Z is omitted.

The fixing device 50 includes a tubular film 51 (fixing rotary member) as a heating member and a pressure member as a pressure member that contacts the outer peripheral surface (surface) of the film to form a nip portion N (fixing nip portion). and a pressure roller (hereinafter simply referred to as “roller”) 53 . The fixing device 50 further includes a ceramic heater 54 as a heating element that contacts the inner peripheral surface (inner surface) of the film 51 to heat the film, a holder 52 as a supporting member that supports the heater, and a reinforcing member that reinforces the holder. and a stay 55 as

The film 51 has a tubular base layer 51a, an elastic layer 51b provided on the outer peripheral surface of the base layer, and a release layer 51c provided on the outer peripheral surface of the elastic layer. These layers are made of polyimide for the base layer 51a, silicone rubber for the elastic layer 51b, and PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) for the release layer 51c. The thickness of each layer is 50 μm for the base layer 51a, 200 μm for the elastic layer 51b, and 20 μm for the release layer 51c. The outer diameter of the film 51 is 18 mm.

The holder 52 inserted through the hollow portion of the film 51 is a member having rigidity, heat resistance, and heat insulation, and is made of liquid crystal polymer. In the direction X, the holder 52 has a concave portion 52a on the flat surface on the roller 53 side, and the heater 54 is supported by this concave portion. This holder 52 also serves as a guide member for guiding the rotation of the film 51 .

Heater 54 has an elongated substrate 54a. A heating resistor layer 54b made of silver-palladium as a heating resistor that generates heat when energized is provided along the longitudinal direction of the substrate 54a on the roller 53 side surface of the substrate 54a. A glass layer 54c is further provided on the roller 53 side of the substrate 54a as a protective layer covering the heat generating resistor layer 54b in order to ensure insulation and abrasion resistance of the heat generating resistor layer 54b.

A stay 55 is installed in the hollow portion of the film 51 on the surface opposite to the surface of the holder 52 on the roller 53 side. The stay 55 has a role of reinforcing the holder 52 .

The roller 53 includes a core metal 53a made of metal such as iron or aluminum, an elastic layer (second elastic layer) 53b provided on the outer peripheral surface of the core metal, and an adhesive layer provided on the outer peripheral surface of the elastic layer. It has a heat conductive layer (first elastic layer) 53c as a layer and a release layer (surface layer) 53d provided on the outer peripheral surface of the heat conductive layer. Materials and manufacturing methods for the elastic layer 53b, the heat conductive layer 53c, and the release layer 53d will be described in detail in (3) below.

As shown in FIG. 2, both ends of a metal core 53a of the roller 53 are rotatably supported by the left and right frames F of the fixing device 50 via bearings B in the direction X. As shown in FIG. The frame F further supports the holder 52 and both ends of the stay 55 .

Both ends of the stay 55 are pressed by springs S in a direction orthogonal to the generatrix direction of the film 51 (recording material thickness direction Y). With this pressure, the holder 52 presses the heater 54 against the inner surface of the film 51 to press the film surface against the outer peripheral surface (surface) of the roller 53 . As a result, the elastic layer 53b of the roller 53 is crushed and elastically deformed, and a nip portion N having a predetermined width is formed in the recording material conveying direction Z by the surface of the roller and the surface of the film.

A heat fixing operation of the fixing device 50 will be described.

When the gear G provided at one end of the metal core 53a of the roller 53 is rotated by the motor M (see FIG. 2), the roller rotates in the direction of the arrow in FIG. The inner surface of the film 51 slides on the glass layer 54c of the heater 54 and rotates in the direction of the arrow in FIG. Grease (not shown) is applied to the inner surface of the film 51 in order to reduce the frictional force generated between it and the holder 52 and between it and the heater 54 due to the rotation of the film 51 .

When electric power is supplied from a power source (not shown) to the heating resistor layer 54b of the heater 54, the heating resistor layer generates heat and the temperature of the heater rises rapidly. A temperature control unit (not shown) controls power supply to the heater so that the temperature of the heater 54 detected by the thermistor TH as a temperature detecting member supported by the holder 52 is maintained at a predetermined fixing temperature (target temperature). Control.

The recording material P carrying the unfixed toner image T is heated while being nipped and conveyed by the nip portion N, whereby the toner image is fixed on the recording material.

(3) Roller 53
Each layer of the roller 53 will be described with reference to FIGS. 3 and 4. FIG. 3A is a perspective view of the roller 53, and FIG. 3B is a sectional view showing the layer structure of the roller 53. As shown in FIG.

(3-1) Elastic layer 53b
The thickness of the elastic layer 53b is not particularly limited as long as the nip portion N having a predetermined width can be formed in the recording material conveying direction Z, but is preferably 2 to 10 mm. Here, the thickness refers to the radial dimension of the roller 53 .

As the material of the elastic layer 53b, general heat-resistant solid rubber such as silicone rubber, foamed sponge rubber, or the like can be used. These rubbers have sufficient heat resistance and durability when used in the fixing device 50, and have preferable elasticity (softness). Therefore, general heat-resistant solid rubber such as silicone rubber and foamed sponge rubber are suitable as the main material for the elastic layer 53b.

A method of forming the elastic layer 53b is not particularly limited, but general molding can be suitably used.

(3-2) Thermal conductive layer 53c
The heat conductive layer 53c is provided between the elastic layer 53b and the release layer 53d. FIG. 4 is a photograph of a cut portion of the heat conductive layer 53c in the thickness direction observed with a scanning electron microscope. In FIG. 4, C indicates the circumferential direction of the roller 53, and O indicates the orientation direction of the filler 53g. As will be described later, a filler with a coating on its surface is referred to as a filler 53g, and a filler without a coating is referred to as a filler 53j. A bundle of fillers 53g is referred to as a filler bundle 53G.

As shown in FIG. 4, the heat conductive layer 53c has a base agent 53e and fibrous heat conductive fillers 53g (more precisely, filler bundles 53G) contained in the base agent. . A heat-resistant rubber material containing an adhesive component or a heat-resistant rubber material not containing an adhesive component is used as the base material 53e. As a heat-resistant rubber material containing an adhesive component, an addition curing silicone rubber adhesive can be used.

The addition-curable silicone rubber adhesive specifically contains an organopolysiloxane having an unsaturated hydrocarbon group represented by a vinyl group, a hydrogen organopolysiloxane, and a platinum compound as a cross-linking catalyst. Then, the organopolysiloxane, hydrogenorganopolysiloxane, and platinum compound are cured by an addition reaction. A known adhesive can be used as such an adhesive.

Examples of self-adhesive components include:
- At least one, preferably two or more selected from the group consisting of alkenyl groups such as vinyl groups, (meth)acryloxy groups, hydrosilyl groups (SiH groups), epoxy groups, alkoxysilyl groups, carbonyl groups, and phenyl groups a silane having a functional group of
-Organosilicon compounds such as cyclic or linear siloxanes having 2 to 30 silicon atoms, preferably 4 to 20 silicon atoms,
- Contains 1 or more and 4 or less aromatic rings such as a phenylene structure having a valence of 1 or more and 4 or less, and contains at least 1 functional group that can contribute to a hydrosilylation addition reaction in a molecule (which may contain oxygen atoms in the molecule), non-silicon organic compounds.

Here, an aromatic ring such as a phenylene structure having a valence of 2 or more and 4 or less is preferable for the aromatic ring having a phenylene structure having a valence of 1 or more and 4 or less. Moreover, it is preferable to contain 1 or more and 2 or less aromatic rings, such as a phenylene structure, in 1 molecule with respect to aromatic rings, such as a phenylene structure, which are contained 1 or more and 4 or less in one molecule. Examples of functional groups that can contribute to the hydrosilylation addition reaction include alkenyl groups and (meth)acryloxy groups. Moreover, it is preferable that one molecule contains 2 to 4 functional groups that can contribute to the hydrosilylation addition reaction. In the above non-silicon organic compounds, the non-silicon type refers to a system containing no silicon atom in the molecule.

The above self-adhesive components can be used singly or in combination of two or more.

Such addition-curable silicone rubber adhesives are commercially available and readily available.

As the heat-resistant rubber material that does not contain an adhesive component, a heat-resistant rubber material such as silicone rubber or fluororubber can be used. When silicone rubber is used as a heat-resistant rubber material that does not contain an adhesive component, addition-curable silicone rubber is preferable from the viewpoint of availability and ease of processing.

53 g of fillers have a role as a filler for ensuring the thermal conductivity of the thermally-conductive layer 53c. By dispersing the filler 53g in the silicone rubber adhesive or silicone rubber as the base agent 53e, a heat flow path can be formed in the base agent. Further, it is preferable that the filler 53g has an elongated fiber shape. When the fiber-shaped filler 53g is used and kneaded with a pre-cured liquid silicone rubber adhesive or silicone rubber, it is easily oriented in the flow direction, that is, the direction X during molding. Therefore, in the direction X, the thermal conductivity of the roller 53 can be enhanced.

FIG. 5 is a perspective view of the fixing device 50 showing a state in which a small-sized recording material is being conveyed at the nip portion N. As shown in FIG. As shown in FIG. 5, since the length of the recording material is shorter than the length of the heating resistor layer 54b of the heater 54 in the direction X, there are non-passing areas on both sides of the passage area of the nip portion N through which the recording material does not pass. occurs. Here, since heat is taken away by the recording material, the passing area becomes a low temperature part, and the non-passing area where heat is not taken away by the recording material becomes a high temperature part.

The non-passing area accumulates heat as the recording material is continuously passed, and the temperature rises more and more. At this time, the heat conduction layer 53c of the roller 53 efficiently disperses heat from the high-temperature portion of the non-passing area to the low-temperature portion of the passing area. This is because the rotation of the roller 53 enables heat to be dispersed using the entire circumference of the roller.

In order to effectively dissipate heat, it is desirable that the heat conductive layer 53c be provided between the elastic layer 53b and the release layer 53d as in this embodiment. The reason for this is that the surface of the release layer 53d is where the temperature difference between the non-passing area and the passing area of the recording material is greatest, and the closer to the release layer, the more likely it is to disperse the heat. is.

Further, in order to disperse heat in the direction X of the roller 53, it is desirable that the filler 53g is oriented not in the thickness direction of the heat conductive layer 53c but in the in-plane direction. Here, the in-plane direction of the heat conductive layer 53c means a direction parallel to the X direction or a direction substantially parallel to the X direction.

FIG. 6(a) is a cross-sectional view in the direction X of the heat conductive layer 53c containing short fillers 53h, and FIG. 6(b) is a cross-sectional view in the direction X of the heat conductive layer 53c containing long fillers 53g.

FIG. 6A shows a case where the length of the filler 53h (100 μm)<the thickness of the heat conductive layer 53c (200 μm). It shows that the filler 53h is also oriented in the thickness direction of the heat conductive layer when the heat conduction layer is formed. FIG. 6B is a diagram showing a case where the length of the filler 53g (2 mm)>the thickness of the heat conductive layer 53c (200 μm) as in this embodiment, and the heat conductive layer 53c is molded. This indicates that the filler 53g cannot be oriented in the thickness direction of the heat conductive layer 53c and tends to be oriented in the in-plane direction.

In this way, when it is desired to orient the filler 53g in the in-plane direction of the heat conductive layer 53c, it is desirable that the length of the filler 53g > the thickness of the heat conductive layer 53c (hereinafter referred to as relational expression 1). .

Furthermore, in order to increase the amount of heat transported in the direction X of the heat conductive layer 53c, it is better to increase the thickness of the heat conductive layer. is desirable.

The method of molding the heat conductive layer 53c is not particularly limited, but generally molding methods such as mold molding and coat molding can be used. Moreover, it is also possible to use the ring coating method disclosed in Japanese Patent Application Laid-Open No. 2003-190870 and Japanese Patent Application Laid-Open No. 2004-290853. The thermally conductive layer 53c can be seamlessly formed on the outer periphery of the elastic layer 53b by the various methods described above. The thickness of the heat conductive layer 53c is preferably 0.1 to 5 mm not only from the viewpoint of performance but also from the viewpoint of molding.

FIG. 7 is a cross-sectional view of the filler 53g or the filler bundle 53G cut along the XC plane of FIG. FIG. 7(a) is a sectional view of one filler 53g, (b) is a sectional view of three bundled fillers 53g, and (c) is eight bundled bundles shown in FIG. (d) is a cross-sectional view of six fillers 53g gathered in a bundle.

The filler 53g used in this embodiment is carbon fiber with a diameter of about 9 μm. The outer peripheral surface of the filler 53g is coated with a binder (adhesive) 53i. As a result, the fillers 53g can be bonded to each other by the binder 53i, so that the fillers can be bundled together like a filler bundle 53G. The binder 53i used in this embodiment is an epoxy resin.

As a pattern in which the fillers 53g are bundled together, as shown in FIG. 7B, each of the fillers 53g-1, 53g-2, and 53g-3 is in contact with two adjacent ones on the outer peripheral surface. may be taken as the basic bundle. By repeating the basic bundle, a skeleton of the bundle as shown in FIG. 7(c) is formed.

Alternatively, as shown in (d) of FIG. 7, although the filler 53g-4 is in contact with two adjacent fillers 53g-5 and 53g-6 on the outer peripheral surface, the filler 53g-5 and the filler 53g are in contact with each other. In some cases, the state in which two of -6 are not in contact with each other is used as a basic bundle.

That is, in both cases of FIGS. 7C and 7D, a plurality of fillers 53g and fillers are formed around a basic filler bundle 53G in which at least two fillers 53g are in contact with the outer periphery of one filler 53g. A bundle 53G is assembled.

If the length of the filler 53g is as short as several tens to several hundred μm, it is difficult to obtain high thermal conductivity in the heat conductive layer 53c because each filler 53g cannot transport heat to a long distance. On the other hand, when the length of the filler 53g is as long as 1 mm or more, the chances of the fillers 53g coming into contact with each other increase, and each filler 53g can transport heat farther. High thermal conductivity is easily obtained.

However, if an attempt is made to knead the filler 53j, which is a long fiber not coated with the binder 53i and has a length of 1 mm or longer, and the base material 53e, the fillers 53j will become entangled with each other, resulting in an increase in the viscosity of the kneaded product. As a result, the long filler 53j may be pulverized into short pieces during the kneading process.

On the other hand, if the filler bundle 53G in which a plurality of fillers 53g whose surfaces are coated with the binder 53i are bundled is used as in the present embodiment, the filler is less likely to bend when the filler bundle 53G and the base material 53e are kneaded. It is possible to suppress the entanglement of the fillers. Furthermore, the area of the filler bundle 53G that contacts the base agent is smaller than that of the filler 53j that is not bundled, so that the viscosity can be lowered. Therefore, it is possible to disperse the filler 53g in the filler bundle 53G in the base material 53e while maintaining the state of long fibers of 1 mm or more.

Also, from the viewpoint of obtaining good fixability, the use of the filler bundle 53G as in this embodiment is preferable to the case of using the filler 53j that is not bundled for the reasons described below. is superior.

As one means for obtaining good fixability, it is conceivable to form a wide nip portion N in the recording material conveying direction Z by reducing the hardness of the roller 53 . This is because the wider the width of the nip portion N, the longer it takes for the heat of the heater 54 to be transferred to the recording material P through the film 51 .

That is, when the filler 53j which is not bundled is used, the hardness of the roller 53 is high, and the width of the nip portion N becomes narrow, so that good fixability cannot be obtained. On the other hand, when the filler bundle 53G is used as in the present embodiment, the hardness of the roller 53 can be lowered, so that a wide nip portion N and good fixability can be obtained. be. This mechanism will be described with reference to FIGS. 8 and 9. FIG.

FIG. 8 is a schematic diagram showing the orientation of unbundle-like fillers 53j dispersed in the heat-conducting layer 53c. FIG. 9 is a schematic diagram showing the orientation of the filler bundles 53G dispersed in the thermally conductive layer 53c. 8 and 9 both show the orientation state of the filler 53j (filler bundle 53G) in the heat conductive layer 53c in the region 53k of the roller 53 shown in FIG. 3(a).

FIG. 8(a) shows how the filler 53j is oriented in the direction X of the roller 53. As shown in FIG. However, not all the fillers 53j are oriented in the direction X, and some are distributed while being inclined in the circumferential direction C of the roller 53. FIG. Therefore, the fillers 53j oriented in the direction X and the fillers 53j inclined in the circumferential direction C intersect at a plurality of locations, thereby exhibiting the effect of reinforcing the heat conductive layer 53c.

As a result, as shown in FIG. 8B, when a force is applied to bend the heat conductive layer 53c in the circumferential direction C of the roller 53, the heat conductive layer is less likely to bend due to the reinforcing effect described above. has increased in hardness.

On the other hand, in the present embodiment, as shown in FIG. 9A, a filler bundle 53G in which the filler 53g is bundled with a binder 53i is used. can be distributed Therefore, as shown in FIG. 8(b), some fillers 53g are distributed while being inclined in the circumferential direction C of the roller 53, but the fillers oriented in the direction X are separated from each other so as to be in contact with each other. As a result, the reinforcing effect was less likely to be exerted.

As a result, as shown in FIG. 9(b), when a force is applied to bend the heat conductive layer 53c in the circumferential direction C of the roller 53, good bendability can be obtained, and the filler 53j which is not bundled can be removed. It was possible to reduce the hardness of the roller while maintaining the same thermal conductivity as that used.

(3-3) Release layer (surface layer) 53d
The release layer 53d is formed by covering the outer peripheral surface of the heat conductive layer 53c with a PFA tube. The thickness of the release layer 53d is not particularly limited as long as it can impart sufficient release properties to the roller 53, but is preferably 20 to 100 μm.

(3-4) Examples of Roller 53 First, Table 1 shows filler bundles 53G or fillers 53j used for each roller 53 according to Examples 1, 2, Comparative Examples 1, and 2. As the filler bundle 53G and the filler 53j, the following pitch-based carbon fibers manufactured by Nippon Graphite Fiber Co., Ltd. were used. The carbon fibers with the trade names XN-80C-02S and XN-80C-01S are filler bundles 53G in which the carbon fibers are bundled with a coating agent, and the carbon fibers with the trade names XN-80C-02 and XN-80C-01 The fiber is a filler 53j made of carbon fiber without coating.

In Table 1, the sizing agent is a coating agent for carbon fibers and corresponds to the binder 53i described in this example. In the product to which the sizing agent is applied, the outer periphery of the carbon fiber is coated with about 2% by mass of epoxy resin per carbon fiber.

Method for manufacturing rollers of Examples and Comparative Examples [Example 1]
First, an elastic layer 53b having a thickness of 3.5 mm is formed on the outer peripheral surface of an aluminum core metal 53a having a diameter of Φ13 by a molding method using an addition curing silicone rubber having a density of 1.20 g/cm ³ . . Thus, an elastic layer covering having a diameter of Φ20 is obtained. Here, the temperature conditions for cross-linking the silicone rubber are 150° C.×30 minutes.

Next, a method of molding the heat conductive layer 53c based on silicone rubber adhesive will be described. Addition-curable silicone rubber adhesive (trade name: SE1819CV A&B) and liquids A and B manufactured by Dow Corning Toray Co., Ltd. are mixed in a ratio of 1:1 to obtain an adhesive stock solution. The adhesive undiluted solution is not limited to this, and other adhesive undiluted solutions may be used.

Pitch-based carbon fiber XN-80C-02S, which is a fibrous thermally conductive filler bundle 53G coated with epoxy resin and bundled into a bundle, was uniformly distributed to the adhesive stock solution so as to have a volume ratio of 15%. was blended and kneaded to obtain an adhesive composition 1. This adhesive composition 1 was uniformly applied to the outer peripheral surface of the elastic layer covering 1 to a thickness of 200 μm.

Further, a PFA tube (thickness: 50 μm) was coated as the release layer 53d on the outer peripheral surface of the adhesive composition 1, and cured by heating at 200° C. for 10 minutes.

[Comparative Example 1]
First, an elastic layer 53b having a thickness of 3.5 mm is formed in the same manner as in Example 1 to obtain an elastic layer covering 1 having a diameter of Φ20.

Next, a method of molding the heat conductive layer 53c based on silicone rubber adhesive will be described. Pitch-based carbon fiber XN-80C-02 not coated with epoxy resin was uniformly blended and kneaded in the same silicone rubber adhesive stock solution as in Example 1 so that the volume ratio was 15%, and adhesion was performed. Agent composition 2 was obtained. However, since the epoxy resin was not coated and the fibers were not bundled, the carbon fibers were entangled and became difficult to knead with the adhesive stock solution, as described above.

Therefore, when a stronger stirring step than in Example 1 was performed, some of the carbon fibers contained in the adhesive composition after kneading became shorter than in Example 1. This adhesive composition 2 was uniformly applied to the outer peripheral surface of the elastic layer covering 1 to a thickness of 200 μm.

Further, a PFA tube (thickness: 50 μm) was coated as the release layer 53d on the outer peripheral surface of the adhesive composition 2, and cured by heating at 200° C. for 10 minutes.

[Example 2]
First, an elastic layer 53b having a thickness of 2.7 mm is formed on the outer peripheral surface of an aluminum core 53a having a diameter of Φ13 by molding using an addition curing silicone rubber having a density of 1.20 g/cm ³ . Thus, an elastic layer covering 2 of Φ18.4 is obtained. Here, the temperature conditions were 150° C.×30 minutes for heat curing.

Next, a method of molding the heat conductive layer 53c based on a heat-resistant rubber material that does not contain an adhesive component will be described. An addition-curable silicone rubber undiluted solution is used as a heat-resistant rubber material that does not contain an adhesive component. Pitch-based carbon fiber XN-80C-01S, which is coated with epoxy resin and has a filler bundle of 53G, is uniformly blended and kneaded with this addition-curable silicone rubber stock solution so that the volume ratio is 7%, and the silicone is A rubber composition 1 was obtained.

Next, an elastic layer covering 2 with a diameter of Φ18.4 was set in a mold with an inner diameter of Φ20.4 so that the metal cores were equal. Then, the silicone rubber composition 1 was injected between the mold and the elastic layer coating 2, and heat-cured at 150° C. for 60 minutes. get 3 things.

Furthermore, a PFA tube (thickness: 50 μm) was coated on the outer periphery of the elastic layer covering 3 as a release layer 53d.

[Comparative Example 2]
First, an elastic layer 53b having a thickness of 2.7 mm is formed in the same manner as in Example 2 to obtain an elastic layer covering 2 having a diameter of Φ18.4.

Next, a method of molding the heat conductive layer 53c based on silicone rubber will be described. Pitch-based carbon fiber XN-80C-01 not coated with epoxy resin was uniformly blended and kneaded in the same addition-curable silicone rubber stock solution as in Example 2 so that the volume ratio was 7%. A silicone rubber composition 2 was obtained. However, since it was not coated with an epoxy resin, it became difficult to knead with the addition-curable silicone rubber undiluted solution, as described above.

Next, an elastic layer covering 2 with a diameter of Φ18.4 was set in a mold with an inner diameter of Φ20.4 so that the metal cores were equal. Then, the silicone rubber composition 2 is injected between the mold and the elastic layer covering 2, and heat-cured at 150° C. for 60 minutes to form an elastic layer covering 4 having a heat conductive layer 53c with an outer diameter of 20.4. obtain.

Furthermore, the outer periphery of the elastic layer covering 4 was covered with a PFA tube (thickness: 50 μm) as a release layer 53d.

[Performance evaluation]
<hardness>
In this example, the hardness was measured using an ASKER Durometer Type C (ASKER-C type hardness tester) manufactured by Kobunshi Keiki Co., Ltd., conforming to JIS K7312 and SRIS0101 standards.

FIG. 10 is a diagram showing hardness measurement positions of the roller 53 in a direction orthogonal to the recording material conveying direction Z. FIG. After molding the roller 53, the surface of the heat-conducting layer 53c and the surface of the elastic layer 53b were obtained by scraping the outer peripheral surface of the release layer 53d with sandpaper in the region indicated by a. By measuring measurement points b1, b2, and b3 with an ASKER-C type hardness meter, the hardness of the roller 53 in the completed state, the hardness of the region where the heat conductive layer 53c is formed on the elastic layer 53b, and the hardness of the elastic layer 53b was evaluated for hardness.

<Nip width>
In a state in which the pressure applied by the spring S of the fixing device 50 is released, pressure-sensitive paper (manufactured by Fuji Film Co., Ltd., Prescale) is sandwiched between the surface of the roller 53 and the surface of the film 51, and then a predetermined pressure is applied by the spring. was applied to the fixing device. The pressure from the spring S of the fixing device 50 was released again, and the pressure-sensitive paper was pulled out. The width of the nip portion N in the recording material conveying direction Z in the pressurized state of the fixing device 50 was measured from the color change of the pressure-sensitive paper.

(Fixability)
Fixability and performance evaluation of excessive temperature rise in the following recording material non-passing area were evaluated by printing at a process speed of 180 mm/s and a fixing temperature of 200°C.

A 5 mm square test pattern was printed on A4 size paper (80 g/m ² ), the test pattern area was rubbed with silbon paper, and the fixability was evaluated by measuring the density change rate of the test pattern before and after rubbing.
○: Average density change rate of less than 20% ×: Average density change rate of 20% or more A density decrease rate of less than 20% is desirable.

(Excessive temperature rise in non-passing area)
The length of the heating resistor layer 54b of the heater 54 in this embodiment is 220 mm. Since the paper width (length in the direction X) of A4 size paper is 210 mm, recording material non-passage areas of 5 mm are generated on both sides of the A4 size paper. Therefore, the surface temperature of the film 51 in the non-passing area was measured when 300 sheets of A4 size paper (80 g/m ² ) were continuously printed. In this example, the excessive temperature rise in the non-passing area was evaluated in the following two stages.
◯: Temperature of non-passing area is less than 230° C. ×: Temperature of non-passing area is 230° C. or higher When the surface temperature of the film 51 in the recording material non-passing area exceeds 230° C., the hardness of the elastic layer 51b of the film may increase. be. As a result, unevenness in the hardness of the elastic layer 51b of the film 51 occurs in the direction X, which may lead to defective transport. Therefore, it is desirable that the temperature of the non-passing area of the film 51 be less than 230.degree.

(Evaluation results)
Table 2 shows a list of evaluation results. In the rollers 53 according to Example 1, Comparative Example 1, Example 2, and Comparative Example 2, the hardness at the measurement point b3 was 32°.

In the roller 53 according to Example 1, the hardness at the measurement point b2 is 39°, which is within a hardness increase of only 7° with respect to the measurement point b3. This is because the filler (carbon fiber) 53g contained in the heat conductive layer 53c is bundled as described above, so that the heat conductive layer 53c is easily bent in the circumferential direction of the roller 53 as shown in FIG. This is because As a result, the hardness at the measurement point b1 was 52°, the width of the nip portion could be widened to 8 mm, and good fixability with an average density reduction rate of 13% could be obtained. The temperature of the recording material non-passing area of the film 51 was 225° C., and a sufficient temperature rise suppressing effect was observed.

In the roller 53 according to Comparative Example 1, the hardness at the measurement point b2 is 46°, which is 14° higher than that at the measurement point b3. As a result, the hardness at the measurement point b1 was 57°, the width of the nip portion was as narrow as 6 mm, and poor fixing occurred (average density decrease rate of 25%).

Furthermore, the temperature of the non-passing portion of the film 51 was 235° C., which is higher than that of the first embodiment.

In the roller 53 according to Example 2, the hardness of the measurement point b2 is 39° and the hardness of the measurement point b1 is 52° due to the effect that the filler (carbon fiber) 53g is bundled in the same manner as in Example 1. A nip width of 8 mm could be obtained. The fixability was also good, and the average density reduction rate was 13%. Moreover, the temperature of the non-passing portion of the film 51 was 225° C., and a sufficient temperature rise suppressing effect was observed in the non-passing region.

In the roller 53 according to Comparative Example 2, since the filler (carbon fiber) 53j is not bundled in the same manner as in Comparative Example 1, the hardness at the measurement point b2 is 47° and the hardness at the measurement point b1 is 58°. The width of the nip portion is as narrow as 6 mm. As a result, poor fixing occurred (average density decrease rate of 26%). Moreover, the temperature of the non-passing portion was 234° C., which is 9° C. higher than that of the second embodiment.

(4) Others Although the epoxy resin was used as the binder 53i in Examples 1 and 2, other materials may be used in consideration of the binding property with the base agent 53e. Further, although the elastic layer 53b is formed of solid rubber, it may be formed of foamed sponge rubber. In addition, although silicone rubber is used as the heat-resistant rubber that serves as the base of the heat-conducting layer 53c, foamed sponge rubber may also be used.

A filler bundle 53G in which a plurality of fiber-like fillers 53g are bundled may be dispersed in at least one of the elastic layer 53b and the heat conductive layer 53c.

In the film heating type fixing device 50, the heater 54 is not limited to a ceramic heater, and may be a heating element heated by a nichrome wire, or a metal heating element that generates heat by electromagnetic induction. Further, the heater 54 does not necessarily have to be positioned at the nip portion N, and may be positioned upstream of the nip portion in the recording material conveying direction.

The roller 53 is applicable not only to the film heating type fixing device 50 but also to an electromagnetic induction heating type fixing device in which the film 51 itself is a cylindrical metal film that generates heat by electromagnetic induction.

50 fixing device, 53 pressure roller (roller), 53a core bar, 53b elastic layer (second elastic layer), 53c heat conduction layer (elastic layer, adhesive layer, first elastic layer), 53d release layer, 53g filler, 53G filler bundle, T unfixed toner image, P recording material

Claims (11)

A roller used in a fixing device for fixing an image formed on a recording material to the recording material,
core metal,
and an elastic layer provided around the core metal,
In the elastic layer, filler bundles in which a plurality of fiber-like fillers are bundled are dispersed ,
The thickness of the filler bundle is smaller than the thickness of the elastic layer,
The orientation of the plurality of fillers contained in the filler bundle is aligned,
The filler bundle is oriented in a direction along the axial direction of the roller,
The roller , wherein the filler bundle is a bundle of the filler having an average fiber length of 2 mm or less . 2. The roller according to claim 1, wherein said filler bundle is formed by bonding a plurality of said fillers with an adhesive. 3. The roller of claim 2, wherein said adhesive is an epoxy resin. A roller according to any preceding claim, wherein the filler is carbon fiber. The roller according to any one of claims 1 to 4, wherein the filler bundle is a bundle of filler having an average fiber length of 1 mm or more. Assuming that the elastic layer is the first elastic layer, the roller further includes a second elastic layer provided between the metal core and the first elastic layer, and a second elastic layer surrounding the first elastic layer. and a surface layer provided, wherein the first elastic layer is an adhesive layer that bonds the second elastic layer and the surface layer, according to any one of claims 1 to 5 Roller as described. 7. A roller according to claim 6 , wherein said adhesive layer is a silicone rubber adhesive. 3. The filler bundle is a bundle in which a plurality of the fillers are gathered around a bundle in which at least two fillers are in contact with the surface of one filler as a core. 8. The roller according to any one of 1 to 7 . A fixing device for fixing an image formed on a recording material to the recording material,
a fixing rotating body;
9. The roller according to any one of claims 1 to 8 , which forms a fixing nip portion that nips and conveys a recording material together with the fixing rotary member;
A fixing device comprising: 10. The fixing device according to claim 9 , wherein the fixing rotator is a cylindrical film. 11. The fixing device according to claim 10 , further comprising a heater that contacts the inner surface of the film.

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