Endless belt, fixing device, and image forming apparatus

Abstract

To provide an endless belt that has high thermal conductivity on an inner peripheral surface while reducing the slide resistance on the inner peripheral surface.SOLUTION: An endless belt includes: a metallic base material; and a heat-resistance resin layer that is provided as a most inner layer on an inner peripheral surface of the metallic base material, and includes resin and thermally conductive filler having an aspect ratio of 20 or more, wherein the orientation ratio of the thermally conductive filler to a circumferential direction of the endless belt is 20% or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an endless belt, a fixing device, and an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses "an image heating device having a flexible cylindrical film, a nip portion forming member in contact with the inner surface of the film, and a pressure member forming a nip portion together with the nip portion forming member via the film, and heating a recording material carrying a toner image while transporting it through the nip portion, wherein the image heating device has a rough surface portion that satisfies skewness Rsk<0 in an area of ​​the inner surface of the film that slides against the nip portion forming member."

[0003] Patent Document 2 discloses "a fixing belt used for heat fixing a toner image on a recording material by rotating while sliding against a backup member on its inner surface, the fixing belt having at least a cylindrical substrate made of metal and a sliding layer made of a heat-resistant resin formed on the inner peripheral surface side of the cylindrical substrate and sliding against the backup member, the sliding layer containing a shape-anisotropic filler, the aspect ratio of the filler being 5 or more, and the length direction of the filler being oriented so as to be approximately parallel to the longitudinal direction of the fixing belt."

[0004] Patent Document 3 discloses a fixing device having "a film body having at least a surface layer, a base layer, and an inner layer, a pressure roller that is in pressure contact with the film body to form a nip portion, and a driving means for rotating the pressure roller, wherein the film is rotated by rotating the pressure roller, and a recording material is sandwiched and transported in the nip portion and heated and pressurized, the fixing device being characterized in that the inner layer has a porous shape." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2012-198516 A [Patent Document 2] JP 2014-228729 A [Patent Document 3] JP 2019-028273 A Summary of the Invention [Problem to be solved by the invention]

[0006] The endless belt is used, for example, as a fixing belt of a fixing device. In the fixing device, for example, a pressing member and a heat source are arranged on the inner peripheral surface side of the endless belt, and the endless belt rotates while being pressed and heated from the inner peripheral surface side. At this time, the inner peripheral surface of the endless belt slides against the pressing member or a sliding member provided between the pressing member and the endless belt, so that an endless belt with reduced sliding resistance on the inner peripheral surface is required.

[0007] In an endless belt using a metal substrate, for example, a heat-resistant resin layer is provided on the inner peripheral surface of the metal substrate to improve the sliding property on the inner peripheral surface of the endless belt. However, when a heat-resistant resin layer is provided on the inner peripheral surface of the metal substrate, the thermal conductivity on the inner peripheral surface of the endless belt may be reduced. If the thermal conductivity on the inner peripheral surface of the endless belt is low, the heat released from the heat source disposed inside the endless belt may easily accumulate in the endless belt, and the time required for the endless belt to reach the fixing temperature may be increased.

[0008] The object of the present invention is to provide an endless belt having a metal base material and a heat-resistant resin layer provided as an innermost layer on the inner surface of the metal base material, the heat-resistant resin layer containing a resin and a heat-conductive filler having an aspect ratio of 20 or more, the endless belt having high thermal conductivity on the inner surface while reducing sliding resistance on the inner surface, compared to a case in which the orientation rate of the heat-conductive filler in the circumferential direction of the endless belt is less than 20%, or the arithmetic mean roughness Ra in the width direction of the endless belt on the inner surface of the heat-resistant resin layer is less than 0.01 μm or exceeds 1.2 μm, or the average spacing Sm of irregularities is less than 10 μm or exceeds 500 μm. [Means for solving the problem]

[0009] Specific means for solving the above problems include the following aspects.

[0010] <1> A metal substrate; a heat-resistant resin layer provided as an innermost layer on an inner peripheral surface of the metal substrate, the heat-resistant resin layer including a resin and a heat-conductive filler having an aspect ratio of 20 or more, the heat-conductive filler having an orientation rate of 20% or more in the circumferential direction of the endless belt; An endless belt having <2> A metal substrate; a heat-resistant resin layer provided as an innermost layer on an inner circumferential surface of the metal substrate, the heat-resistant resin layer including a resin and a thermally conductive filler having an aspect ratio of 20 or more, the arithmetic mean roughness Ra of the inner circumferential surface in the width direction of the endless belt being 0.01 μm or more and 1.2 μm or less and the mean spacing Sm of irregularities being 10 μm or more and 500 μm or less; An endless belt having

[0011] <3> The thermally conductive filler is a carbon-based filler. <1> or <2> 2. The endless belt according to claim 1 . <4> The carbon-based filler is a carbon nanotube. <3> 2. The endless belt according to claim 1 .

[0012] <5> The thermal conductivity ratio between the metal substrate and the thermally conductive filler (metal substrate / thermally conductive filler) is 1 / 100 or more and 1 / 3 or less. <1> ~ <4> 2. The endless belt according to claim 1 . <6> The thermal conductivity of the thermally conductive filler is 200 W / mK or more and 1500 W / mK or less. <5> 2. The endless belt according to claim 1 .

[0013] <7> The orientation rate of the thermally conductive filler in the width direction of the endless belt is 20% or more and 80% or less. <1> ~ <6> 2. The endless belt according to claim 1 . <8> The thickness of the heat-resistant resin layer gradually increases from the center to the ends in the width direction of the endless belt. <1> ~ <7> 2. The endless belt according to claim 1 .

[0014] <9> <1> ~ <8> A first rotating body comprising the endless belt according to any one of the above items, A second rotor arranged in contact with an outer circumferential surface of the first rotor; a pressing member disposed inside the first rotating body and pressing the first rotating body against the second rotating body from an inner circumferential surface of the first rotating body; A fixing device comprising: <10> An image carrier; a charging device for charging the surface of the image carrier; a latent image forming device for forming a latent image on the charged surface of the image carrier; a developing device for developing the latent image with toner to form a toner image; a transfer device for transferring the toner image onto a recording medium; The toner image is fixed onto a recording medium. <9> a fixing device according to the above; An image forming apparatus comprising: Effect of the Invention

[0015] <1> According to the invention, in an endless belt having a metal substrate and a heat-resistant resin layer provided as an innermost layer on the inner surface of the metal substrate, the heat-resistant resin layer containing a resin and a heat-conductive filler having an aspect ratio of 20 or more, the endless belt has high thermal conductivity on the inner surface while reducing sliding resistance on the inner surface, compared to a case in which the orientation rate of the heat-conductive filler in the circumferential direction of the endless belt is less than 20%. <2> According to the invention, there is provided an endless belt having a metal base material and a heat-resistant resin layer provided as an innermost layer on the inner surface of the metal base material, the heat-resistant resin layer containing a resin and a heat-conductive filler having an aspect ratio of 20 or more. Compared to a case in which the arithmetic mean roughness Ra of the inner surface of the heat-resistant resin layer in the width direction of the endless belt is less than 0.01 μm or exceeds 1.2 μm, or the average spacing Sm of irregularities is less than 10 μm or exceeds 500 μm, there is provided an endless belt having high thermal conductivity on the inner surface while reducing sliding resistance on the inner surface.

[0016] <3> According to the invention, in an endless belt having a metal base material and a heat-resistant resin layer provided as an innermost layer on the inner circumferential surface of the metal base material, the heat-resistant resin layer containing a resin and a heat-conductive filler which is a carbon-based filler having an aspect ratio of 20 or more, the endless belt has high thermal conductivity on the inner circumferential surface while reducing sliding resistance on the inner circumferential surface, compared to a case in which the orientation rate of the heat-conductive filler in the circumferential direction of the endless belt is less than 20%, or the arithmetic mean roughness Ra in the width direction of the endless belt on the inner circumferential surface of the heat-resistant resin layer is less than 0.01 μm or exceeds 1.2 μm, or the average spacing Sm of irregularities is less than 10 μm or exceeds 500 μm. <4> According to the invention, in an endless belt having a metal substrate and a heat-resistant resin layer provided as an innermost layer on the inner surface of the metal substrate, the heat-conductive filler being a resin and a carbon nanotube having an aspect ratio of 20 or more, the orientation rate of the heat-conductive filler in the circumferential direction of the endless belt is less than 20%, or the arithmetic mean roughness Ra in the width direction of the endless belt on the inner surface of the heat-resistant resin layer is less than 0.01 μm or exceeds 1.2 μm, or the average spacing Sm of irregularities is less than 10 μm or exceeds 500 μm, the endless belt has high thermal conductivity on the inner surface while reducing sliding resistance on the inner surface, compared to a case in which the orientation rate of the heat-conductive filler in the circumferential direction of the endless belt is less than 20%, or the arithmetic mean roughness Ra in the width direction of the endless belt on the inner surface of the heat-resistant resin layer is less than 0.01 μm or exceeds 1.2 μm, or the average spacing Sm of irregularities is less than 10 μm or exceeds 500 μm.

[0017] <5> According to the present invention, an endless belt having high thermal conductivity on the inner circumferential surface is provided, compared to a case in which the thermal conductivity ratio between the metal base material and the thermally conductive filler exceeds 1 / 3. <6> According to the present invention, an endless belt having high thermal conductivity on the inner circumferential surface is provided, as compared with a case in which the thermal conductivity of the thermally conductive filler is less than 200 W / mK.

[0018] <7> According to the present invention, an endless belt is provided in which the sliding resistance on the inner peripheral surface is reduced, compared to a case in which the orientation rate of the thermally conductive filler in the width direction of the endless belt is more than 80%. <8> According to the present invention, an endless belt is provided in which deviation in the width direction during rotation is suppressed compared to when the thickness of the heat-resistant resin layer is constant from the center to the ends in the width direction of the endless belt.

[0019] <9> or <10> According to the invention, there is provided a fixing device or image forming apparatus in which an endless belt having a metal base material and a heat-resistant resin layer provided as an innermost layer on the inner surface of the metal base material, the heat-conductive filler containing a resin and an aspect ratio of 20 or more is applied, the orientation rate of the heat-conductive filler in the circumferential direction of the endless belt is less than 20%, or the inner surface of the heat-resistant resin layer has an arithmetic mean roughness Ra in the width direction of the endless belt of less than 0.01 μm or more than 1.2 μm, or an average spacing Sm of irregularities in the width direction of the endless belt of less than 10 μm or more than 500 μm, while reducing the sliding resistance on the inner surface. [Brief description of the drawings]

[0020] [Figure 1] 1 is a schematic diagram illustrating an example of a layer structure of an endless belt according to an embodiment of the present invention. [Diagram 2] 1 is a schematic diagram illustrating a first fixing device which is an example of a configuration of a fixing device according to the present embodiment. [Diagram 3] 4 is a schematic diagram showing a second fixing device which is another example of the configuration of the fixing device according to the present embodiment. FIG. [Figure 4] 1 is a schematic diagram illustrating an example of the configuration of an image forming apparatus according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] [Endless belt] <First embodiment> The endless belt according to the first embodiment has a metal base material and a heat-resistant resin layer provided as an innermost layer on an inner circumferential surface of the metal base material, the heat-resistant resin layer containing a resin and a heat-conductive filler having an aspect ratio of 20 or more, and having an orientation rate of the heat-conductive filler in the circumferential direction of the endless belt of 20% or more. Hereinafter, the orientation rate of the heat-conductive filler in the circumferential direction of the endless belt is also referred to as "orientation rate (circumferential direction) A".

[0022] As described above, in an endless belt using a metal substrate, for example, a heat-resistant resin layer is provided on the inner peripheral surface of the metal substrate in order to improve the sliding property on the inner peripheral surface of the endless belt. However, when a heat-resistant resin layer is provided on the inner peripheral surface of the metal substrate, the thermal conductivity on the inner peripheral surface of the endless belt may be reduced. If the thermal conductivity of the inner peripheral surface of the endless belt is low, heat tends to accumulate in the endless belt, and it may become difficult to continuously fix images on recording media (hereinafter also referred to as "small-sized media") having a width smaller than the heating width in the width direction of the endless belt. Specifically, in the region of the endless belt in the width direction through which the small-sized media pass, heat is easily removed by contact with the small-sized media, whereas in the region through which the small-sized media do not pass, heat is not removed and accumulates, causing partial high temperatures, which may make continuous image fixing difficult. Furthermore, if the thermal conductivity of the inner peripheral surface of the endless belt is low, a large amount of heat is required for the endless belt to reach the fixing temperature, which may lengthen the warm-up time of the fixing device.

[0023] In contrast, in the first embodiment, the heat-resistant resin layer provided as the innermost layer on the inner surface of the metal base material contains resin and a thermally conductive filler having an aspect ratio of 20 or more, and has an orientation rate (circumferential direction) A of 20% or more. Therefore, when the heat-resistant resin layer contains the heat-conductive filler oriented in one direction, the heat-resistant resin layer has improved thermal conductivity compared to a heat-resistant resin layer that does not contain the heat-conductive filler. In other words, the heat conductivity of the inner peripheral surface of the endless belt is improved. As a result, partial temperature rise caused by continuous image fixing on small-sized media is suppressed, and the warm-up time of the fixing device is also shortened.

[0024] In addition, since the heat-resistant resin layer contains the heat-conductive filler oriented in the circumferential direction of the endless belt, the sliding resistance on the inner peripheral surface of the endless belt is reduced compared to when the heat-conductive filler is oriented in the width direction of the endless belt or when the heat-conductive filler is not contained. Although the reason for this is unclear, it is speculated that the unevenness on the inner peripheral surface of the heat-resistant resin layer caused by the heat-conductive filler is aligned along the circumferential direction of the endless belt, and the contact state of the pressing member or the sliding member with respect to the inner peripheral surface of the heat-resistant resin layer during rotation of the endless belt is stabilized, thereby reducing the sliding resistance. If the sliding resistance on the inner peripheral surface of the endless belt is high, this may result in an increase in the rotation load of the endless belt, misalignment in the width direction of the endless belt when rotating (i.e., meandering of the endless belt), generation of abnormal noise, etc. However, as described above, in the first embodiment, the sliding resistance on the inner peripheral surface of the endless belt is reduced, so that an increase in the rotation load of the endless belt, misalignment in the width direction of the endless belt, generation of abnormal noise, etc. are also suppressed. For the reasons described above, it is presumed that the endless belt of the first embodiment has high thermal conductivity on its inner circumferential surface while reducing the sliding resistance on the inner circumferential surface.

[0025] <Second embodiment> The endless belt according to the second embodiment has a metal base material and a heat-resistant resin layer provided as an innermost layer on an inner circumferential surface of the metal base material, the heat-resistant resin layer including a resin and a thermally conductive filler having an aspect ratio of 20 or more, and having an arithmetic mean roughness Ra of 0.01 μm or more and 1.2 μm or less in the width direction of the endless belt and an average spacing Sm of irregularities of 10 μm or more and 500 μm or less on the inner circumferential surface.

[0026] As described above, when a heat-resistant resin layer is provided on the inner peripheral surface of an endless belt using a metal substrate in order to improve the sliding property on the inner peripheral surface of the metal substrate, the thermal conductivity on the inner peripheral surface of the endless belt may decrease. In contrast, in the second embodiment, the heat-resistant resin layer, which is the innermost layer, contains resin and a thermally conductive filler having an aspect ratio of 20 or more, and the arithmetic mean roughness Ra of the inner surface in the width direction of the endless belt is 0.01 μm or more and 1.2 μm or less, and the average spacing Sm of the irregularities is 10 μm or more and 500 μm or less. Therefore, when the heat-resistant resin layer contains the heat-conductive filler, the heat conductivity of the heat-resistant resin layer is improved compared to a heat-resistant resin layer that does not contain the heat-conductive filler. In other words, the heat conductivity of the inner peripheral surface of the endless belt is improved. As a result, a partial temperature rise caused by continuously fixing images on small-sized media is suppressed, and the warm-up time of the fixing device is also shortened.

[0027] In addition, since the arithmetic mean roughness Ra in the width direction of the endless belt on the inner peripheral surface of the heat-resistant resin layer is 0.01 μm to 1.2 μm and the average interval Sm of the irregularities is 10 μm to 500 μm, the sliding resistance on the inner peripheral surface of the endless belt is reduced compared to the case where the arithmetic mean roughness Ra and the average interval Sm of the irregularities are out of the above range. Although the reason is unclear, it is presumed that the inner peripheral surface of the heat-resistant resin layer has moderate irregularities at moderate intervals in the width direction of the endless belt, so that the contact state of the pressing member or the sliding member with the inner peripheral surface of the heat-resistant resin layer during the rotation of the endless belt is stabilized, thereby reducing the sliding resistance. Furthermore, the reduction in the sliding resistance also suppresses an increase in the rotation load of the endless belt, a shift in the width direction of the endless belt, and the generation of abnormal noise. For the reasons described above, it is presumed that the endless belt of the second embodiment has high thermal conductivity on its inner circumferential surface while reducing the sliding resistance on the inner circumferential surface.

[0028] Hereinafter, an endless belt that corresponds to both the endless belt according to the first embodiment and the endless belt according to the second embodiment will be referred to as an "endless belt according to this embodiment." However, an example of the endless belt of the present invention may be an endless belt that corresponds to at least one of the endless belt according to the first embodiment and the endless belt according to the second embodiment.

[0029] Hereinafter, an endless belt according to an embodiment of the present invention will be described with reference to the drawings. In the following explanation, an endless belt having a metal substrate, a heat-resistant resin layer provided on the inner peripheral surface of the metal substrate, an elastic layer provided on the outer peripheral surface of the metal substrate, and a release layer provided on the outer peripheral surface of the elastic layer will be taken as an example.

[0030] Fig. 1 shows an example of a layer structure of an endless belt according to the present embodiment. The endless belt 110 shown in Fig. 1 has a metal substrate 120, a heat-resistant resin layer 130 provided on the inner peripheral surface of the metal substrate 120, an elastic layer 140 provided on the outer peripheral surface of the metal substrate 120, and a release layer 150 provided on the outer peripheral surface of the elastic layer 140.

[0031] In FIG. 1, an endless belt having a metal substrate 120, a heat-resistant resin layer 130, an elastic layer 140, and a release layer 150 is described as an example, but the endless belt according to the present embodiment is not limited to the above configuration. The endless belt according to the present embodiment may be an endless belt having at least a metal substrate and a heat-resistant resin layer, with the heat-resistant resin layer being the innermost layer, and may be, for example, an endless belt without a release layer, or an endless belt further having other layers. Examples of the other layers include an adhesive layer provided between the metal substrate and the heat-resistant resin layer, between the metal substrate and the elastic layer, etc.

[0032] Each layer constituting the slide member according to this embodiment will be specifically described below. In the following description, reference numerals will be omitted.

[0033] <Metal substrate> The metal substrate is not particularly limited as long as it is an endless substrate made of a metal material. Examples of metal materials include various metals such as SUS, nickel, copper, and aluminum. Among these, SUS and nickel (electroformed) are preferred from the viewpoints of thermal conductivity and strength.

[0034] The thickness of the metal substrate is not particularly limited, and from the viewpoint of having mechanical strength and ensuring flexibility, it is preferably from 20 μm to 200 μm, more preferably from 30 μm to 150 μm, even more preferably from 40 μm to 130 μm, and particularly preferably from 40 μm to 100 μm. From the viewpoint of mechanical strength, it is preferable that the thickness of the base material does not change along the axial direction (that is, the width direction of the endless belt).

[0035] <Heat-resistant resin layer> The heat-resistant resin layer is a layer provided on the inner peripheral surface of the metal substrate, and contains a resin and a thermally conductive filler having an aspect ratio of 20 or more. In addition to the resin and the thermally conductive filler having an aspect ratio of 20 or more, the heat-resistant resin layer may contain other additives as necessary. The heat-resistant resin layer may be provided directly on the inner peripheral surface of the metal substrate, or may be provided via another layer such as an adhesive layer. From the viewpoint of obtaining high thermal conductivity in the thickness direction of the endless belt, it is preferable that the heat-resistant resin layer is provided directly on the inner peripheral surface of the metal substrate. In addition, when the heat-resistant resin layer is provided via another layer, it is preferable that the other layer is a layer having high thermal conductivity (for example, a thermal conductivity of 20 W / mK or more at 150°C). Here, heat resistance means the property of not melting or decomposing even when the temperature of the fixing device is reached (for example, 230°C. When continuous narrow paper is passed through, the temperature of the non-paper passing areas rises significantly and can reach around 230°C because the paper does not absorb heat).

[0036] (resin)

[0037] Examples of the resin contained in the heat-resistant resin layer include polyimide, polyimideamide, polyamide, polyester, polyethylene terephthalate, polyethersulfone, polyetherketone, polyetheretherketone (PEEK) polysulfone, fluororesin, fluorinated polyimide, polybenzimidazole, polyphenylene sulfide, and polyetherimide. Among these, the resin contained in the heat-resistant resin layer is preferably a heat-resistant resin such as polyimide, polyimideamide, or polyetheretherketone (PEEK) from the viewpoint of heat resistance. The heat-resistant resin layer may contain only one type of resin, or may contain two or more types of resins. Polyimide and polyimide amide will be described below as examples of resin.

[0038] -Polyamide-imide- There are no particular limitations on the polyamideimide, so long as it is a resin having imide bonds and amide bonds in the repeating unit. More specifically, the polyamideimide may be a polymer of a trivalent carboxylic acid compound (also called tricarboxylic acid) having an acid anhydride group and a diisocyanate compound or a diamine compound.

[0039] As the tricarboxylic acid, trimellitic anhydride and its derivatives are preferable. In addition to the tricarboxylic acid, tetracarboxylic dianhydride, aliphatic dicarboxylic acid, aromatic dicarboxylic acid, etc. may be used in combination.

[0040] Examples of the diisocyanate compound include 3,3'-dimethylbiphenyl-4,4'-diisocyanate, 2,2'-dimethylbiphenyl-4,4'-diisocyanate, biphenyl-4,4'-diisocyanate, biphenyl-3,3'-diisocyanate, biphenyl-3,4'-diisocyanate, 3,3'-diethylbiphenyl-4,4'-diisocyanate, 2,2'-diethylbiphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, 2,2'-dimethoxybiphenyl-4,4'-diisocyanate, naphthalene-1,5-diisocyanate, and naphthalene-2,6-diisocyanate. The diamine compound may be a compound having a structure similar to that of the above-mentioned isocyanate, but having an amino group instead of the isocyanato group.

[0041] -Polyimide- Examples of polyimides include imidized products of polyamic acids (precursors of polyimides), which are polymers of tetracarboxylic dianhydrides and diamine compounds.

[0042] Specific examples of tetracarboxylic dianhydrides used as raw materials for polyimides include pyromellitic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2'-bis(3,4-dicarboxyphenyl)sulfonic dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, and ethylenetetracarboxylic dianhydride.

[0043] Specific examples of diamine compounds used as raw materials for polyimide include 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 3,3'-dichlorobenzidine, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3'-dimethyl 4,4'-biphenyldiamine, benzidine, and 3,3'-dimethylbenzidine. Benzidine, 3,3'-dimethoxybenzidine, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenylpropane, 2,4-bis(β-amino-tert-butyl)toluene, bis(p-β-amino-tert-butylphenyl)ether, bis(p-β-methyl-δ-aminophenyl)benzene, bis-p-(1,1-dimethyl-5-amino-pentyl)benzene, 1-isopropyl-2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di(p- Aminocyclohexyl)methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3 -methylheptamethylenediamine, 5-methylnonamethylenediamine, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 12-diaminooctadecane, 2,2-bis[4-(4-aminophenoxy)phenyl]propane, piperazine, H2N(CH2)3O(CH2)2O(CH2)NH2, H2N(CH2)3S(CH2)3NH2, H2N(CH2)3N(CH3)2(CH2)3NH2, and the like.

[0044] (Thermal conductive filler) The thermally conductive filler contained in the heat-resistant resin layer is not particularly limited as long as it is a thermally conductive filler having an aspect ratio of 20 or more. An example of the thermally conductive filler is a filler having a thermal conductivity of 20 W / mK or more at 150° C. Hereinafter, the thermal conductivity at 150° C. will also be simply referred to as "thermal conductivity".

[0045] Specific examples of the thermally conductive filler having an aspect ratio of 20 or more include carbon-based fillers such as carbon nanotubes and graphite. Among these, carbon nanotubes are preferable from the viewpoint of obtaining high thermal conductivity of the endless belt. The carbon nanotubes may be single-walled carbon nanotubes or multi-walled carbon nanotubes. As the thermally conductive filler, one type may be used alone, or two or more types may be used in combination.

[0046] The aspect ratio of the thermally conductive filler is not particularly limited as long as it is 20 or more. Here, when the thermally conductive filler is fibrous, the aspect ratio of the thermally conductive filler means the length of the thermally conductive filler divided by the major axis (width) of the thermally conductive filler. From the viewpoint of obtaining the effect of the orientation of the thermally conductive filler, the aspect ratio of the thermally conductive filler is preferably 20 or more, more preferably 25 or more, and even more preferably 35 or more. Moreover, from the viewpoint of toughness, the aspect ratio of the thermally conductive filler is preferably 100 or less, more preferably 80 or less, and even more preferably 60 or less.

[0047] When the thermally conductive filler is carbon nanotubes, the average outer diameter of the carbon nanotubes is preferably 0.005 μm or more and 2 μm or less, more preferably 0.01 μm or more and 1.5 μm or less, even more preferably 0.02 μm or more and 1.0 μm or less, and particularly preferably 0.05 μm or more and 0.5 μm or less, from the viewpoint of dispersibility in the resin. From the viewpoint of reducing the sliding resistance on the inner surface of the endless belt while obtaining high thermal conductivity on the inner surface, the average outer diameter of the carbon nanotubes is preferably 10 to 300 times the average thickness of the heat-resistant resin layer, more preferably 20 to 250 times, and even more preferably 30 to 200 times.

[0048] Furthermore, when the thermally conductive filler is carbon nanotubes, the average length of the carbon nanotubes is preferably 0.5 μm or more and 100 μm or less, more preferably 1 μm or more and 60 μm or less, even more preferably 2 μm or more and 20 μm or less, and particularly preferably 3 μm or more and 10 μm or less, from the viewpoint of toughness to the layer containing carbon nanotubes (CNTs).

[0049] The aspect ratio of the thermally conductive filler and the average outer diameter and average length of the carbon nanotubes are determined by observing 100 or more target thermally conductive fillers with an optical microscope, determining the images obtained, and taking the arithmetic mean. When measuring the aspect ratio of the thermally conductive filler contained in the heat-resistant resin layer, the surface of the heat-resistant resin layer may be observed with an optical microscope, or the resin contained in the heat-resistant resin layer may be dissolved with a solvent and the remaining thermally conductive filler may be observed with an optical microscope.

[0050] From the viewpoint of obtaining high thermal conductivity on the inner peripheral surface of the endless belt, the thermal conductivity of the thermally conductive filler is preferably 50 W / mK or more, and more preferably 100 W / mK or more. The upper limit of the thermal conductivity of the thermally conductive filler is not particularly limited. The thermal conductivity of the thermally conductive filler may be 3000 W / mK or less.

[0051] The thermal conductivity of the thermally conductive filler is measured, for example, using a thermal conductivity measuring device (ai-Phase Mobile manufactured by Ai-Phase Co., Ltd.) When measuring the thermal conductivity of the thermally conductive filler contained in the heat-resistant resin layer, for example, the resin contained in the heat-resistant resin layer is dissolved with a solvent, and the above measurement is performed on the remaining thermally conductive filler.

[0052] From the viewpoint of obtaining high thermal conductivity on the inner peripheral surface of the endless belt, the thermal conductivity ratio between the metallic substrate and the thermally conductive filler (metallic substrate / thermally conductive filler), i.e., the ratio of the thermal conductivity of the metallic substrate to the thermal conductivity of the thermally conductive filler, is preferably 1 / 100 or more and 1 / 3 or less, more preferably 1 / 80 or more and 1 / 4 or less, and even more preferably 1 / 60 or more and 1 / 6 or less. When the thermal conductivity ratio (metal substrate / thermally conductive filler) is in the above range, the thermal conductivity of the thermally conductive filler is high compared to when it is greater than the above range, and the thermal conductivity on the inner peripheral surface of the endless belt is also likely to be high. Also, when the thermal conductivity ratio (metal substrate / thermally conductive filler) is in the above range, the sliding maintenance is likely to be high compared to when it is less than the above range. The thermal conductivity of the metal substrate is measured in the same manner as in the measurement of the thermal conductivity of the thermally conductive filler.

[0053] The content of the thermally conductive filler contained in the heat-resistant resin layer is not particularly limited, and from the viewpoint of obtaining high thermal conductivity on the inner circumferential surface while reducing the sliding resistance on the inner circumferential surface of the endless belt, the content is preferably 5 parts by mass or more and 30 parts by mass or less, more preferably 8 parts by mass or more and 25 parts by mass or less, and even more preferably 10 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the resin contained in the heat-resistant resin layer.

[0054] (Orientation rate) The thermally conductive filler is contained in the heat-resistant resin layer so that the orientation rate (circumferential direction) A is 20% or more. Here, the orientation rate (circumferential direction) A is expressed by the following formula, where N is the total number of thermally conductive fillers, and N' is the number of thermally conductive fillers for which the inclination θ of the major axis direction of the thermally conductive filler with respect to the circumferential direction of the endless belt is -30°≦θ≦30°. Formula: A = (N' / N) x 100 When the thermally conductive filler is a carbon nanotube, the long diameter direction of the thermally conductive filler means the length direction of the carbon nanotube.

[0055] The orientation rate (circumferential direction) A is 20% or more, and from the viewpoint of obtaining high thermal conductivity on the inner peripheral surface while reducing the sliding resistance on the inner peripheral surface of the endless belt, it is preferably 20% or more, more preferably 25% or more, even more preferably 30% or more, and particularly preferably 40% or more. The upper limit of the orientation rate (circumferential direction) A is not particularly limited, and may be 100%, 80% or less, 75% or less, or 70% or less.

[0056] From the viewpoint of obtaining high thermal conductivity on the inner peripheral surface while reducing the sliding resistance on the inner peripheral surface of the endless belt, the orientation rate of the thermally conductive filler in the width direction of the endless belt is preferably 20% to 80%, more preferably 25% to 75%, and even more preferably 30% to 70%. Hereinafter, the orientation rate of the thermally conductive filler in the width direction of the endless belt is also referred to as "orientation rate (width direction) B". When the orientation rate (width direction) B is within the above range, the sliding properties are superior compared to when it is greater than the above range, and the axial strength is superior compared to when it is smaller than the above range. The width direction of the endless belt means the direction of the rotation axis of the endless belt. In addition, the orientation rate (width direction) B is expressed by the following formula, where N is the total number of thermally conductive fillers, and N'' is the number of thermally conductive fillers whose inclination θ' of the major axis direction of the thermally conductive filler with respect to the width direction of the endless belt satisfies -30°≦θ'≦30°. Formula: B=(N'' / N)×100

[0057] The ratio A / B of the orientation rate (circumferential direction) A to the orientation rate (width direction) B is preferably 1.0 or more. By setting the ratio A / B within the above range, it is possible to obtain high thermal conductivity on the inner peripheral surface while reducing the sliding resistance on the inner peripheral surface of the endless belt, compared to a case where the ratio is smaller than the above range.

[0058] The orientation rate (circumferential direction) A and the orientation rate (width direction) B are measured by the following method. Specifically, the inner surface of the heat-resistant resin layer is observed with an optical microscope at 10 equally spaced locations from one end to the other end of the heat-resistant resin layer in the width direction of the endless belt, and for 50 or more heat-conductive fillers, the total number N of heat-conductive fillers, the number N' of heat-conductive fillers for which the inclination θ of the long diameter direction of the heat-conductive filler relative to the circumferential direction of the endless belt is -30°≦θ≦30°, and the inclination θ' of the long diameter direction of the heat-conductive filler relative to the width direction of the endless belt is -30°≦θ'≦30° are counted, and the orientation rate (circumferential direction) A and the orientation rate (width direction) B are calculated.

[0059] As a method for controlling the orientation rate (circumferential direction) A and the orientation rate (width direction) B within the above range, for example, a method of forming a heat-resistant resin layer using a spiral coating method and adjusting the coating conditions can be mentioned. In the spiral coating method, for example, while rotating the metal base, and while moving a discharge part that discharges the coating liquid for forming a heat-resistant resin layer onto the inner peripheral surface of the metal base from one end to the other end in the direction of the rotation axis of the metal base (i.e., the width direction of the endless belt), the coating liquid for forming a heat-resistant resin layer is discharged onto the inner peripheral surface of the metal base. Then, the orientation rate (circumferential direction) A and the orientation rate (width direction) B are controlled by adjusting the rotation speed of the metal base, the movement speed of the discharge part in the direction of the rotation axis of the metal base, and the discharge amount of the coating liquid for forming a heat-resistant resin layer per unit time.

[0060] (Method of forming heat-resistant resin layer) The heat-resistant resin layer can be formed, for example, through a method including a coating liquid preparation step of preparing a coating liquid for forming a heat-resistant resin layer that becomes a heat-resistant resin layer when heated, a coating step of applying the coating liquid for forming a heat-resistant resin layer to the inner peripheral surface of a metal substrate to form a coating film, and a heating step of heating the coating film. The heating step may include, for example, a plurality of steps in which heating is performed at different temperatures. Specifically, the heating step may include, for example, a drying step in which the coating film is dried (i.e., the solvent in the coating film is removed) and a baking step in which the dried coating film is heated and baked at a temperature higher than that in the drying step.

[0061] - Coating solution preparation process - In the coating liquid preparation step, a coating liquid for forming a heat-resistant resin layer, which becomes a heat-resistant resin layer when heated, is prepared. The heat-resistant resin layer-forming coating liquid may, for example, contain a solvent, at least one of a resin precursor and a resin, a thermally conductive filler, and, if necessary, other additives.

[0062] The solvent is appropriately selected depending on the type of at least one of the resin precursor and the resin used, and specific examples include organic polar solvents. Specific examples of organic polar solvents include sulfoxide-based solvents such as dimethyl sulfoxide and diethyl sulfoxide; formamide-based solvents such as N,N-dimethylformamide and N,N-diethylformamide; acetamide-based solvents such as N,N-dimethylacetamide and N,N-diethylacetamide; pyrrolidone-based solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone; phenol-based solvents such as phenol, o-, m-, or p-cresol, xylenol, halogenated phenols, and catechol; ether-based solvents such as tetrahydrofuran, dioxane, and dioxolane; alcohol-based solvents such as methanol, ethanol, and butanol; cellosolve-based solvents such as butyl cellosolve; and hexamethylphosphoramide and γ-butyrolactone. The solvent may be used alone or in combination of two or more kinds.

[0063] The content of the solvent in the coating liquid for forming a heat-resistant resin layer is preferably in the range of 70% by mass to 80% by mass, and more preferably 76% by mass to 78% by mass, based on the total amount of the coating liquid for forming a heat-resistant resin layer.

[0064] The viscosity (at 25° C.) of the coating liquid for forming the heat-resistant resin layer is not particularly limited, but is preferably in the range of 1 Pa·s to 100 Pa·s, and more preferably in the range of 3 Pa·s to 50 Pa·s. The viscosity of the coating liquid is measured in an environment of 25° C. using a constant speed viscometer PK100 manufactured by HAKKE Corporation.

[0065] The coating liquid for forming a heat-resistant resin layer may be prepared, for example, by dissolving at least one of a resin precursor and a resin in a solution in which a thermally conductive filler is dispersed in a solvent, or by dispersing a thermally conductive filler in a solution in which at least one of a resin precursor and a resin is dissolved in a solvent. Examples of the method for dispersing the thermally conductive filler include known methods such as a ball mill, a sand mill, a bead mill, and a jet mill (opposed collision type disperser).

[0066] -Coating process- In the coating step, the coating liquid for forming the heat-resistant resin layer is applied to the inner peripheral surface of the metal substrate to form a coating film. Examples of a method for forming a coating film on the inner peripheral surface of the metal substrate include a spiral coating method. Specifically, in the spiral coating method, a coating liquid for forming a heat-resistant resin layer is discharged from a discharge part to coat the inner peripheral surface of the metal base while rotating the metal base around its axis with the direction of the rotation axis of the metal base being a horizontal direction. Then, while the metal base is being rotated, the discharge part is moved from one end to the other end in the direction of the rotation axis of the metal base while the coating liquid for forming a heat-resistant resin layer is discharged from the discharge part. As a result, the coating liquid for forming a heat-resistant resin layer is applied in a spiral shape to the inner peripheral surface of the metal base to form a coating film.

[0067] -Heating process- In the heating step, the coating film formed in the coating step is heated to remove the solvent in the coating film and form a heat-resistant resin layer. In the heating step, for example, a high-temperature (higher than the heating temperature) gas is fed from one end of the metal base in the axial direction to the other end to heat the coating film on the inner peripheral surface of the metal base. As described above, the heating step may include, for example, a drying step for drying the coating film and a baking step for heating and baking the dried coating film. The heating temperature in the drying step is, for example, 120° C. or higher and 220° C. or lower, and preferably 140° C. or higher and 210° C. or lower. The heating temperature in the baking step is, for example, a higher temperature than the heating temperature in the drying step, and is preferably 200° C. or higher and 300° C. or lower, and more preferably 240° C. or higher and 280° C. or lower.

[0068] (Thickness and characteristics) From the viewpoint of obtaining high thermal conductivity on the inner circumferential surface while reducing the sliding resistance on the inner circumferential surface of the endless belt, the average thickness of the heat-resistant resin layer is preferably 1 μm or more and 40 μm or less, more preferably 3 μm or more and 30 μm or less, and even more preferably 5 μm or more and 20 μm or less. The average thickness of the heat-resistant resin layer is the average value of the values ​​measured at five equally spaced points from one end to the other end in the width direction of the endless belt on the heat-resistant resin layer, and is measured using a micrometer or the like.

[0069] From the viewpoint of obtaining high thermal conductivity on the inner peripheral surface while reducing the sliding resistance on the inner peripheral surface of the endless belt, the average thickness of the heat-resistant resin layer is preferably 0.01 to 1 times the thickness of the metal substrate, more preferably 0.05 to 0.8 times, and even more preferably 0.1 to 0.4 times.

[0070] It is preferable that the thickness of the heat-resistant resin layer gradually increases from the center to the ends in the width direction of the endless belt. It is presumed that the increase in the thickness of the heat-resistant resin layer toward the ends suppresses the endless belt from shifting in the width direction when the endless belt rotates, and the endless belt is less likely to meander, thereby suppressing the occurrence of wrinkles in the recording medium. From the viewpoint of suppressing deviation in the width direction of the endless belt, the thickness of the heat-resistant resin layer at the end portion in the width direction of the endless belt is preferably 1 to 3 times, and more preferably 1 to 2.5 times, the thickness of the heat-resistant resin layer at the center portion in the width direction of the endless belt. In addition, when the thickness of the elastic layer is gradually increased from the center portion in the width direction of the endless belt toward the end portion, the thickness of the heat-resistant resin layer does not have to be increased from the center portion in the width direction of the endless belt toward the end portion.

[0071] As a method for gradually increasing the thickness of the heat-resistant resin layer from the center to the ends in the width direction of the endless belt, for example, a method of forming the heat-resistant resin layer by using a spiral coating method and adjusting the coating conditions can be mentioned.Specific examples of the method include a method of changing the moving speed of the discharge part in the rotation axis direction of the metal base from the center to the ends in the width direction of the endless belt, and a method of changing the discharge amount of the coating liquid for forming the heat-resistant resin layer per unit time from the center to the ends in the width direction of the endless belt.

[0072] The arithmetic mean roughness Ra in the width direction of the endless belt on the inner surface of the heat-resistant resin layer is 0.01 μm or more and 1.20 μm or less, and from the viewpoint of reducing the sliding resistance on the inner surface of the endless belt, it is preferably 0.05 μm or more and 1.05 μm or less, and more preferably 0.1 μm or more and 0.9 μm or less. The average spacing Sm of the irregularities in the width direction of the endless belt on the inner surface of the heat-resistant resin layer is 10 μm or more and 500 μm or less, and from the viewpoint of reducing the sliding resistance on the inner surface of the endless belt, it is preferably 20 μm or more and 450 μm or less, and more preferably 30 μm or more and 400 μm or less.

[0073] Here, the arithmetic mean roughness Ra and the mean spacing between projections and recesses Sm are based on the JIS B0601 (1994) standard. The arithmetic mean roughness Ra and the mean spacing between projections and recesses Sm are measured using a Tokyo Seimitsu SURFCOM under the following conditions: measurement length: 4 mm, cutoff wavelength: 0.8 mm, cutoff type: Gaussian, and measurement speed: 0.3 mm / s.

[0074] As a method for setting the arithmetic mean roughness Ra and the average spacing Sm of irregularities in the width direction of the endless belt on the inner surface of the heat-resistant resin layer within the above-mentioned ranges, for example, a method in which the orientation rate (circumferential direction) A of the thermally conductive filler contained in the heat-resistant resin layer is set to 20% or more can be mentioned.

[0075] The thermal conductivity of the entire heat-resistant resin layer is preferably 0.6 W / mK or more, and more preferably 0.8 W / mK or more. The upper limit of the thermal conductivity of the entire heat-resistant resin layer is not particularly limited. The thermal conductivity of the inner peripheral surface of the heat-resistant resin layer may be 2.5 W / mK or less. The thermal conductivity of the entire heat-resistant resin layer is measured in the same manner as the thermal conductivity of the thermally conductive filler, except that the thermal conductivity of the entire heat-resistant resin layer is the average value of measurements taken at 10 equally spaced locations from one end to the other end of the heat-resistant resin layer in the width direction of the endless belt.

[0076] <Elastic layer> The elastic layer is a layer provided on the outer peripheral surface of the metal substrate as necessary, and is not particularly limited as long as it is an elastic layer. When the endless belt is used as a fixing belt of a fixing device, the elastic layer is a layer provided from the viewpoint of imparting elasticity to the fixing belt against pressure from the outer peripheral side, and plays a role of, for example, following the unevenness of the toner image on the recording medium and bringing the surface of the fixing belt into close contact with the toner image.

[0077] The elastic layer is preferably made of an elastic material that returns to its original shape even when deformed by the application of an external force of, for example, 100 Pa. Examples of the elastic material used for the elastic layer include fluororesin, silicone resin, silicone rubber, fluororubber, fluorosilicone rubber, etc. As the material for the elastic layer, from the viewpoints of heat resistance, thermal conductivity, insulation, etc., silicone rubber and fluororubber are preferred, and silicone rubber is more preferred.

[0078] Examples of silicone rubber include RTV silicone rubber, HTV silicone rubber, and liquid silicone rubber. Specific examples of silicone rubber include polydimethyl silicone rubber (MQ), methyl vinyl silicone rubber (VMQ), methyl phenyl silicone rubber (PMQ), and fluoro silicone rubber (FVMQ). An example of a commercially available silicone rubber is liquid silicone rubber SE6744 manufactured by Dow Corning Corporation.

[0079] As the silicone rubber, those that mainly use addition reaction type as the crosslinking form are preferred.Also, various types of functional groups are known for silicone rubber, and preferred are dimethyl silicone rubber with methyl group, methylphenyl silicone rubber with methyl group and phenyl group, vinyl silicone rubber with vinyl group (vinyl group-containing silicone rubber), etc.In addition, vinyl silicone rubber with vinyl group is more preferred, and silicone rubber with organopolysiloxane structure with vinyl group and hydrogen organopolysiloxane structure with hydrogen atom (SiH) bonded to silicon atom is more preferred.

[0080] Examples of the fluororubber include vinylidene fluoride rubber, tetrafluoroethylene / propylene rubber, tetrafluoroethylene / perfluoromethylvinyl ether rubber, phosphazene rubber, and fluoropolyether. An example of a commercially available fluororubber product is Viton B-202 manufactured by DuPont Dow Elastomers.

[0081] The elastic material used in the elastic layer preferably contains silicone rubber as a main component (i.e., contains 50% or more by mass), more preferably has a silicone rubber content of 90% or more by mass, and even more preferably has a silicone rubber content of 99% or more by mass.

[0082] In addition to the elastic material, the elastic layer may contain an inorganic filler for the purpose of reinforcement, heat resistance, heat transfer, etc. Examples of the inorganic filler include known ones, and preferred examples thereof include fumed silica, crystalline silica, iron oxide, alumina, and metallic silicon. In addition to the above, examples of inorganic filler materials include well-known inorganic fillers such as carbides (e.g., carbon black, carbon fiber, carbon nanotubes, etc.), titanium oxide, silicon carbide, talc, mica, kaolin, calcium carbonate, calcium silicate, magnesium oxide, graphite, silicon nitride, boron nitride, cerium oxide, and magnesium carbonate. Among these, silicon nitride, silicon carbide, graphite, boron nitride, and carbides are preferred from the viewpoint of thermal conductivity. The content of inorganic filler in the elastic layer may be determined based on the required thermal conductivity, mechanical strength, etc., and may be, for example, from 1% by mass to 20% by mass, preferably from 3% by mass to 15% by mass, and more preferably from 5% by mass to 10% by mass, based on the entire elastic layer.

[0083] In addition, the elastic layer may contain additives such as softeners (paraffin-based, etc.), processing aids (stearic acid, etc.), antioxidants (amine-based, etc.), vulcanizing agents (sulfur, metal oxides, peroxides, etc.), functional fillers (alumina, etc.), etc.

[0084] The thickness of the elastic layer may be, for example, in the range of 30 μm to 600 μm, and preferably in the range of 100 μm to 500 μm. The thickness of the elastic layer may be constant from the center to the ends in the width direction of the endless belt, or may gradually increase from the center to the ends.

[0085] The elastic layer may be formed by a known method, for example, by forming it on the outer circumferential surface of the metal base material by a coating method. When silicone rubber is used as the elastic material of the elastic layer, for example, first, prepare an elastic layer forming coating liquid containing liquid silicone rubber that is cured by heating to become silicone rubber. Next, apply the elastic layer forming coating liquid onto a metal substrate (for example, by flow coating (spiral winding coating)) to form an elastic coating film, and for example, vulcanize the elastic coating film as necessary to form an elastic layer on the metal substrate. The vulcanization temperature in the vulcanization is, for example, 150°C or higher and 250°C or lower, and the vulcanization time is, for example, 30 minutes or higher and 120 minutes or lower.

[0086] <Release layer> The release layer is a layer that is provided on the outer peripheral surface of the elastic layer as necessary, and when the endless belt is used as a fixing belt of a fixing device, this layer plays a role in preventing the molten toner image from adhering to the surface (outer peripheral surface) that comes into contact with the recording medium during fixing.

[0087] The release layer is required to have, for example, heat resistance and releasability. From this viewpoint, it is preferable to use a heat-resistant release material as the material constituting the release layer, and specific examples thereof include fluororubber, fluororesin, silicone resin, polyimide resin, and the like. Among these, fluororesin is preferable as the heat-resistant release material. Specific examples of fluororesins include tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluoroethylene (PCTFE), and vinyl fluoride (PVF).

[0088] The surface of the release layer on the elastic layer side may be subjected to a surface treatment. The surface treatment may be a wet treatment or a dry treatment, and examples of the surface treatment include a liquid ammonia treatment, an excimer laser treatment, and a plasma treatment.

[0089] The thickness of the release layer is preferably in the range of 10 μm to 100 μm, and more preferably in the range of 15 μm to 50 μm.

[0090] The release layer may be formed by a known method, for example, a coating method. The release layer may be formed by preparing a tubular release layer in advance and coating the outer periphery of the elastic layer.

[0091] [Fixing device] The fixing device of this embodiment includes a first rotating body consisting of the endless belt of this embodiment described above, a second rotating body arranged in contact with the outer peripheral surface of the first rotating body, and a pressing member arranged inside the first rotating body and pressing the first rotating body against the second rotating body from the inner peripheral surface of the first rotating body. The fixing device according to the present embodiment may further include a heat source disposed inside the first rotating body. An example of the fixing device according to the present embodiment will be described below with reference to the drawings, but the present invention is not limited to this.

[0092] <First fixing device> FIG. 2 is a schematic diagram showing an example of the first fixing device. The fixing device 60 shown in FIG. 2 has a fixing belt 62 (an example of a first rotating body) consisting of the endless belt related to the present embodiment described above, a pressure roll 64 (an example of a second rotating body), a pressure pad 66 (an example of a pressing member), a halogen lamp 68 (an example of a heat source), and a reflector 70. The outer circumferential surfaces of the fixing belt 62 and the pressure roll 64 are in contact with each other to form a contact area N. The fixing belt 62 and the pressure roll 64 rotate together to transport the recording medium in the contact area.

[0093] The fixing belt 62 is rotatably supported by bearings (not shown) at both axial ends of the fixing belt 62. A drive transmission member (gear, etc.) (not shown) is fitted into one axial end of the fixing belt 62. The fixing belt 62 rotates as the drive transmission member is rotated around an axis by a drive source (motor, etc.) (not shown).

[0094] The pressure roll 64 is provided in contact with the outer circumferential surface of the fixing belt 62 . The pressure roll 64 is made of resin or metal, for example, and is formed in a cylindrical or columnar shape. A bearing member (not shown) is pressed against the pressure pad 66 via the fixing belt 62 by an elastic member (such as a spring) on ​​a part of the outer circumferential surface of the pressure roll 64. As a result, the pressure roll 64 and the fixing belt 62 form a contact area N (so-called a nip portion). That is, the pressure roll 64 has a function of pressing the fixing belt 62 together with the pressure pad 66 in the contact area N by sandwiching the fixing belt 62 therebetween.

[0095] Fitting members (caps, etc.) (not shown) are fitted to both axial ends of the pressure roll 64, increasing the rigidity of the pressure roll 64 against external forces in the radial direction. The fitting members are rotatable about their axes by bearing members (not shown). The pressure roll 64 is rotated in response to the rotation of the fixing belt 62. As a result, the pressure roll 64 rotates together with the fixing belt 62 in the contact area N to transport the recording medium. The fixing belt 62 may be rotated by the rotation of the pressure roll 64 .

[0096] The pressure pad 66 is provided on the inner peripheral surface side of the fixing belt 62 . The pressure pad 66 is, for example, configured of a columnar member made of resin or metal. The pressure pad 66 has a function of pressing the fixing belt 62 together with the pressure roll 64 in a contact area N by pressing the pressure roll 64 against the pressure pad 66 via the fixing belt 62 .

[0097] Alternatively, the pressure pad 66 may be pressed against the pressure roll 64 via the fixing belt 62 by an elastic member (such as a spring). In other words, the pressure pad 66 may be either a member pressed by the pressure roll 64 to pressurize the fixing belt 62, or a member pressing itself against the pressure roll 64 to pressurize the fixing belt 62. Moreover, instead of the pressure pad 66, a roll-shaped pressure member may be provided.

[0098] The halogen lamp 68 is provided on the inner circumferential surface of the fixing belt 62. Specifically, for example, the halogen lamp 68 is provided facing the contact area N via the pressure pad 66. The halogen lamp 68 directly heats the contact area N.

[0099] The halogen lamp 68 is a cylindrical halogen lamp that extends along the width direction (the belt rotation axis direction) of the fixing belt 62. The halogen lamp 68 uses a filament with a small heat capacity as a heat source, so it starts radiating heat quickly after the power is turned on.

[0100] Instead of the halogen lamp 68, a known heat source such as a ceramic heater or a Coltz lamp may be used.

[0101] The reflector 70 is provided on the inner circumferential surface side of the fixing belt 62. Specifically, for example, the reflector 70 is provided facing the contact area N with the halogen lamp 68 interposed therebetween. The reflector 70 is, for example, made of a plate-shaped metal member or a plate-shaped resin member with a metal layer deposited on the reflective surface. The reflector 70 is curved, for example, so that the contact area N side is concave. The reflector 70 has a function of reflecting radiant heat from the halogen lamp 68 toward the contact area N.

[0102] In the fixing device 60 described above, the fixing belt 62 and the pressure roll 64 rotate, and the toner image formed on the recording medium is pressurized and heated in the contact area N between the fixing belt 62 and the pressure roll 64, thereby fixing the toner image to the recording medium. Since the fixing belt 62 is the endless belt according to the present embodiment described above, the thermal conductivity of the fixing belt 62 is high, and the sliding resistance between the inner circumferential surface of the fixing belt 62 and the sliding surface of the pressure pad 66 is reduced. As a result, the warm-up time of the fixing device 60 is short, and partial temperature increases due to continuous image fixing to small-sized media are suppressed, and an increase in rotation load, meandering of the fixing belt 62, generation of abnormal noise, etc. due to the sliding resistance between the fixing belt 62 and the pressure pad 66 are suppressed.

[0103] In addition, since the fixing belt 62 has a small heat capacity and the halogen lamps 68 directly heat the contact area N, the parts of the fixing belt 62 other than the contact area N are easily cooled. Therefore, hot offset due to overshooting is easily suppressed. In addition, the halogen lamp 68 uses a filament with a small heat capacity as a heat source, and is therefore a heating source that starts radiating heat quickly after the power is turned on. Therefore, when the halogen lamp 68 is used, the time for which the power is turned off can be extended, making it easier to suppress hot offset due to overshoot.

[0104] Furthermore, by providing the reflector 70, the contact area N can be heated quickly. In other words, the time for which the power supply to the halogen lamp 68 is turned off can be extended, which makes it easier to suppress hot offset due to overshoot.

[0105] <Second Fixing Device> 3 is a schematic diagram showing an example of the second fixing device, in which the same reference numerals are given to members having substantially the same functions as those of the first fixing device, and the description thereof will be omitted. The fixing device 80 shown in FIG. 3 includes a fixing belt 62 (an example of a first rotating body) consisting of the endless belt according to the embodiment described above, a pressure roll 64 (an example of a second rotating body), a recording medium conveying belt 72, a linear heating element 74 (an example of a pressing member and a heating source), a pulse current section 74A, and a heat sink 76. The outer circumferential surfaces of the fixing belt 62 and the pressure roll 64 contact each other via the recording medium transport belt 72 to form a contact area N. The fixing belt 62 and the pressure roll 64 rotate together to transport the recording medium in the contact area. The contact area N where the outer circumferential surfaces of the fixing belt 62 and the pressure roll 64 come into contact with each other also includes the contact area N where the fixing belt 62 comes into contact with the pressure roll 64 via a member such as the recording medium transport belt 72 .

[0106] The fixing belt 62 is supported while being given tension by rotation support rolls 62A, 62B, and 62C. Of the three rotation support rolls 62A, 62B, and 62C, the first rotation support roll 62B, which is located downstream in the rotation direction of the fixing belt 62 from the position where the linear heating element 74 is disposed, is used as a drive roll that drives the fixing belt 62 to rotate.

[0107] The pressure roll 64 is provided on the inner circumferential surface side of the recording medium transport belt 72. A part of the outer circumferential surface of the pressure roll 64 is pressed against the linear heating element 74 side via the fixing belt 62 and the recording medium transport belt 72 by a bearing member (not shown) and an elastic member (such as a spring). As a result, the pressure roll 64 and the fixing belt 62 form a contact area N (so-called a nip portion) via the recording medium transport belt 72. That is, the pressure roll 64 has a function of pressing the fixing belt 62 and the recording medium transport belt 72 together with the pressure pad 66 in the contact area N by sandwiching them.

[0108] The recording medium transport belt 72 is supported while being given tension by rotation support rolls 72 A, 72 B, and 72 C. The recording medium transport belt 72 is rotated in accordance with the rotation of the fixing belt 62.

[0109] Here, the rotating support rolls 62A, 62B supporting the fixing belt 62 and the rotating support rolls 72A, 72B supporting the recording medium transport belt 72 are disposed opposite to each other via the fixing belt 62 and the recording medium transport belt 72. In other words, the outer peripheral surfaces of the fixing belt 62 and the recording medium transport belt 72 are disposed so as to face each other between the rotating support rolls 62A, 72A and the rotating support rolls 62B, 72B.

[0110] The linear heating element 74 is provided on the inner circumferential surface side of the fixing belt 62. Specifically, the linear heating element 74 is provided facing the contact area N. The linear heating element 74 directly heats the contact area N.

[0111] The linear heating element 74 also has the function of applying pressure to the fixing belt 62 in contact area N together with the pressure roll 64 by pressing the pressure roll 64 against the linear heating element 74 via the fixing belt 62 and the recording medium transport belt 72.

[0112] The linear heating element 74 is made of a long member extending along the width direction (the direction of the endless belt rotation axis) of the fixing belt 62. The linear heating element 74 is, for example, a heat source having a linear heating portion in which a plurality of heating resistors serving as a heat source are arranged in a row on a substrate. In other words, the linear heating element 74 is a heating element that is different from heating elements made of nichrome wire. An example of the linear heating element 74 is a thermal head.

[0113] Pulse current supplying unit 74A is composed of a power source, and is electrically connected to linear heating element 74 in order to supply pulse current to linear heating element 74. Specifically, pulse current supplying unit 74A supplies pulse current to the heating resistor. The shape of the energizing pulse applied by the pulse energizing unit 74A may be a rectangular wave, a triangular wave, a sine wave, etc. Note that it is not necessary to turn off the energization between pulses.

[0114] The pulse current supplying unit 74A is connected to the control unit 40. The control unit 40 controls the pulse current supplying unit 74A to supply pulse current to the linear heating element 74.

[0115] The heat sink 76 is provided in contact with the inner circumferential surface of the fixing belt 62. Specifically, for example, the heat sink 76 is provided downstream of the contact area N in the rotation direction of the fixing belt 62. The heat sink 76 absorbs heat from the fixing belt 62 downstream of the heated contact area N in the rotation direction of the fixing belt 62 and dissipates the heat, thereby cooling the fixing belt 62. This cools the fixed image after the toner image is fixed in the contact area N.

[0116] In the fixing device 80 described above, the recording medium on which the toner image has been formed is pressurized and heated in a contact area N between the fixing belt 62 and the pressure roll 64 via the recording medium conveying belt 72, thereby fixing the toner image to the recording medium. Thereafter, the fixed image on the recording medium is cooled by the heat sink 76 and then separated from the fixing belt 62. Since the fixing belt 62 is the endless belt according to the present embodiment described above, the fixing belt 62 has high thermal conductivity and reduces sliding resistance between the inner circumferential surface of the fixing belt 62 and the sliding surface of the linear heating element 74. As a result, the warm-up time of the fixing device 60 is short, and partial temperature increases due to continuous image fixing on small-sized media are suppressed, and an increase in rotation load, meandering of the fixing belt 62, generation of abnormal noise, etc. due to sliding resistance between the fixing belt 62 and the linear heating element 74 are suppressed.

[0117] In addition, since the contact area N is directly heated by the linear heating element 74, the portions of the fixing belt 62 other than the contact area N are easily cooled. Therefore, hot offset due to overshooting is easily suppressed.

[0118] In addition, since the linear heating element 74 can be divided into many heating regions like a thermal head, the amount of heat generated can be easily controlled, which makes it easier to suppress hot offset caused by overshoot.

[0119] Furthermore, the heat generated by the pulse current supplying section 74A from the linear heating element 74 can be easily controlled in temperature by the pulse waveform, pulse interval, etc. of the pulse current supply. This makes it easier to suppress hot offset due to overshoot.

[0120] Moreover, the fixed image fixed in the contact area N is separated from the fixing belt 62 after being cooled by the heat sink 76 (i.e., after the molten toner constituting the image is solidified). This makes it easier to suppress hot offset. In addition, since the fixing belt 62 is also cooled by the heat sink 76, it makes it easier to suppress hot offset due to overshoot.

[0121] Alternatively, the heat sink 76 may not be provided, and the rotating support roll 72B supporting the recording medium transport belt 72 provided at a position where the fixed image is separated from the fixing belt 62 may be increased in diameter, and the increased diameter rotating support roll 72B may be used as the cooling section. When the rotating support roll 72B is increased in diameter (specifically, for example, when the rotating support roll 72B is increased in diameter compared to the rotating support roll 62B supporting the fixing belt 62), the fixed image is cooled via the recording medium transport belt 72 by the rotating support roll 72B.

[0122] [Image forming equipment] The image forming apparatus according to the present embodiment includes an image carrier, a charging device for charging the surface of the image carrier, a latent image forming device for forming a latent image on the surface of the charged image carrier, a developing device for developing the latent image with toner to form a toner image, a transfer device for transferring the toner image to a recording medium, and the fixing device according to the present embodiment described above for fixing the toner image to the recording medium. The image forming apparatus according to the present embodiment uses the first fixing device described above as the fixing device. An example of an image forming apparatus according to the present embodiment will be described below with reference to the drawings, but the present invention is not limited to this.

[0123] FIG. 4 is a schematic diagram showing the configuration of an example of an image forming apparatus according to the present embodiment. 4 is, for example, an intermediate transfer type image forming apparatus generally called a tandem type, and includes a plurality of image forming units 1Y, 1M, 1C, and 1K in which toner images of each color component are formed by an electrophotographic method, a primary transfer section 10 that sequentially transfers (primary transfer) the toner images of each color component formed by each image forming unit 1Y, 1M, 1C, and 1K onto an intermediate transfer belt 15, a secondary transfer section 20 that collectively transfers (secondary transfer) the superimposed toner images transferred onto the intermediate transfer belt 15 onto a recording medium, paper K, and a fixing device 60 that fixes the secondarily transferred image onto the paper K. The image forming apparatus 100 also includes a control section 40 that transmits and receives information between each device (each section) and controls the operation of each device (each section). The unit including the intermediate transfer belt 15, the primary transfer section 10, and the secondary transfer section 20 corresponds to an example of a transfer device.

[0124] Each of the image forming units 1Y, 1M, 1C, and 1K of the image forming apparatus 100 includes a photoconductor 11 that rotates in the direction of arrow A as an example of an image carrier that carries a toner image formed on its surface.

[0125] Around the photoconductor 11, there is provided a charger 12 as an example of a charging device that charges the photoconductor 11, and there is provided a laser exposure device 13 (the exposure beam is indicated by the symbol Bm in the figure) as an example of a latent image forming device that writes an electrostatic charge image on the photoconductor 11.

[0126] In addition, around the photoconductor 11, there is provided a developing device 14, which is an example of a developing device, that contains toner of each color component and makes the electrostatic charge image on the photoconductor 11 visible using the toner, and there is provided a primary transfer roll 16 that transfers the toner image of each color component formed on the photoconductor 11 to an intermediate transfer belt 15 at the primary transfer section 10. At least one of the color component toners is the specific toner described above. In this embodiment, it is preferable that all of the color component toners are the specific toner described above.

[0127] Furthermore, a photoreceptor cleaner 17 that removes residual toner on the photoreceptor 11 is provided around the photoreceptor 11, and electrophotographic devices including a charger 12, a laser exposure device 13, a developer 14, a primary transfer roll 16, and the photoreceptor cleaner 17 are sequentially arranged along the rotation direction of the photoreceptor 11. These image forming units 1Y, 1M, 1C, and 1K are arranged in a substantially linear fashion in the order of yellow (Y), magenta (M), cyan (C), and black (K) from the upstream side of the intermediate transfer belt 15.

[0128] The intermediate transfer belt 15 is driven (rotated) in a circular manner (in a direction B shown in Fig. 4) by various rolls at a speed suited to the purpose. The various rolls include a drive roll 31 driven by a motor (not shown) to rotate the intermediate transfer belt 15, a support roll 32 that supports the intermediate transfer belt 15 extending in a substantially straight line along the arrangement direction of the photoconductors 11, a tensioning roll 33 that applies tension to the intermediate transfer belt 15 and functions as a correction roll that suppresses meandering of the intermediate transfer belt 15, a back roll 25 provided in the secondary transfer unit 20, and a cleaning back roll 34 provided in a cleaning unit that scrapes off residual toner on the intermediate transfer belt 15.

[0129] The primary transfer section 10 is composed of a primary transfer roll 16 as an opposing member disposed opposite the photoconductor 11 with the intermediate transfer belt 15 sandwiched therebetween. The primary transfer roll 16 is composed of a core body and a sponge layer as an elastic layer fixed to the periphery of the core body. The core body is a cylindrical rod made of a metal such as iron or SUS. The sponge layer is formed of a blend rubber of NBR, SBR and EPDM mixed with a conductive agent such as carbon black, and has a volume resistivity of 10 7.5 Ωcm or more 10 8.5 It is a sponge-like cylindrical roll with a surface resistance of less than Ωcm.

[0130] The primary transfer roll 16 is arranged in pressure contact with the photoconductor 11 with the intermediate transfer belt 15 sandwiched therebetween, and furthermore, a voltage (primary transfer bias) of the opposite polarity to the charge polarity of the toner (negative polarity; the same applies below) is applied to the primary transfer roll 16. As a result, the toner images on the photoconductors 11 are electrostatically attracted to the intermediate transfer belt 15 in sequence, and superimposed toner images are formed on the intermediate transfer belt 15.

[0131] The secondary transfer unit 20 includes a back roll 25 and a secondary transfer roll 22 that is disposed on the toner image bearing surface side of the intermediate transfer belt 15 .

[0132] The back roll 25 is made of a tube of EPDM and NBR blend rubber with carbon dispersed on the surface, and the inside is made of EPDM rubber. 7 Ω / □ or more 10 10 The hardness is set to, for example, 70° (Asker C: manufactured by Kobunshi Keiki Co., Ltd., the same applies below.) The back roll 25 is disposed on the back side of the intermediate transfer belt 15 to constitute an opposing electrode of the secondary transfer roll 22, and is in contact with a metallic power supply roll 26 to which a secondary transfer bias is stably applied.

[0133] On the other hand, the secondary transfer roll 22 is composed of a core body and a sponge layer as an elastic layer fixed around the core body. The core body is a cylindrical rod made of metal such as iron or SUS. The sponge layer is made of a blend rubber of NBR, SBR and EPDM mixed with a conductive agent such as carbon black, and has a volume resistivity of 10 7.5 Ωcm or more 10 8.5 It is a sponge-like cylindrical roll with a surface resistance of less than Ωcm.

[0134] The secondary transfer roll 22 is placed in pressure contact with the back roll 25 with the intermediate transfer belt 15 sandwiched therebetween, and the secondary transfer roll 22 is further grounded to form a secondary transfer bias between the secondary transfer roll 22 and the back roll 25, thereby secondarily transferring the toner image onto paper (an example of a recording medium) K transported to the secondary transfer section 20.

[0135] In addition, an intermediate transfer belt cleaner 35 is provided on the downstream side of the secondary transfer section 20 of the intermediate transfer belt 15 in a manner that allows it to be freely attached and detached, which removes residual toner and paper dust from the intermediate transfer belt 15 after the secondary transfer and cleans the surface of the intermediate transfer belt 15.

[0136] The intermediate transfer belt 15, the primary transfer section 10 (the primary transfer roll 16), and the secondary transfer section 20 (the secondary transfer roll 22) correspond to an example of a transfer unit.

[0137] Meanwhile, a reference sensor (home position sensor) 42 is provided upstream of the yellow image forming unit 1Y to generate a reference signal that serves as a reference for timing image formation in each of the image forming units 1Y, 1M, 1C, and 1K. An image density sensor 43 for adjusting image quality is provided downstream of the black image forming unit 1K. This reference sensor 42 generates a reference signal by recognizing a mark provided on the back side of the intermediate transfer belt 15, and each of the image forming units 1Y, 1M, 1C, and 1K is configured to start image formation in response to an instruction from the control unit 40 based on the recognition of this reference signal.

[0138] Furthermore, in the image forming apparatus according to this embodiment, as transport means for transporting the paper K, there are provided a paper storage section 50 for storing the paper K, a paper feed roll 51 for taking out and transporting the paper K accumulated in the paper storage section 50 at a predetermined timing, a transport roll 52 for transporting the paper K fed by the paper feed roll 51, a transport guide 53 for sending the paper K transported by the transport roll 52 to the secondary transfer section 20, a transport belt 55 for transporting the paper K transported after secondary transfer by the secondary transfer roll 22 to a fixing device 60 (an example of a fixing means), and a fixing entrance guide 56 for guiding the paper K to the fixing device 60.

[0139] The control unit 40 is configured as a computer that controls the entire device and performs various calculations. Specifically, for example, the control unit 40 includes a CPU (Central Processing Unit), a ROM (Read Only Memory) that stores various programs, a RAM (Random Access Memory) that is used as a work area when the programs are executed, a non-volatile memory that stores various information, and an input / output interface (I / O) (all not shown). The CPU, ROM, RAM, non-volatile memory, and I / O are each connected via a bus.

[0140] In addition to the control unit 40, the image forming apparatus 100 is equipped with an operation display unit, an image processing unit, an image memory, a storage unit, a communication unit, and the like (none of which are shown). Each of the operation display unit, image processing unit, image processing unit, image memory, storage unit, and communication unit is connected to the I / O of the control unit 40. The control unit 40 controls each unit by transmitting and receiving information between each of the operation display unit, image processing unit, image memory, storage unit, and communication unit.

[0141] Next, a basic image forming process of the image forming apparatus according to this embodiment will be described. In the image forming apparatus 100 shown in FIG. 4, image data output from an image reading device (not shown) or a personal computer (PC) (not shown) is subjected to image processing by an image processing device (not shown), and then image formation is performed by image forming units 1Y, 1M, 1C, and 1K.

[0142] The image processing device performs image processing on the input reflectance data, such as shading correction, positional deviation correction, brightness / color space conversion, gamma correction, and various image editing such as frame erasure, color editing, and movement editing. The image data that has undergone image processing is converted into color material gradation data of four colors, Y, M, C, and K, and is output to the laser exposure device 13.

[0143] In the laser exposure device 13, an exposure beam Bm emitted from, for example, a semiconductor laser is irradiated onto the photoconductor 11 of each of the image forming units 1Y, 1M, 1C, and 1K in accordance with the input color material gradation data. In each of the photoconductors 11 of the image forming units 1Y, 1M, 1C, and 1K, the surface is charged by the charger 12, and then the surface is scanned and exposed by the laser exposure device 13 to form an electrostatic image. The formed electrostatic image is developed into a toner image of each color of Y, M, C, and K by each of the image forming units 1Y, 1M, 1C, and 1K.

[0144] The toner images formed on the photoconductors 11 of the image forming units 1Y, 1M, 1C, and 1K are transferred onto the intermediate transfer belt 15 in the primary transfer section 10 where each photoconductor 11 comes into contact with the intermediate transfer belt 15. More specifically, in the primary transfer section 10, a voltage (primary transfer bias) of the opposite polarity to the charging polarity (negative polarity) of the toner is applied to the base material of the intermediate transfer belt 15 by the primary transfer roll 16, and the toner images are sequentially superimposed on the surface of the intermediate transfer belt 15 to perform the primary transfer.

[0145] After the toner images are sequentially primarily transferred onto the surface of the intermediate transfer belt 15, the intermediate transfer belt 15 moves to transport the toner images to the secondary transfer unit 20. When the toner images are transported to the secondary transfer unit 20, the transport means rotates the paper feed roll 51 in accordance with the timing at which the toner images are transported to the secondary transfer unit 20, and paper K of the desired size is supplied from the paper storage unit 50. The paper K supplied by the paper feed roll 51 is transported by the transport roll 52 and reaches the secondary transfer unit 20 via the transport guide 53. Before reaching the secondary transfer unit 20, the paper K is temporarily stopped, and an alignment roll (not shown) rotates in accordance with the movement timing of the intermediate transfer belt 15 on which the toner images are held, thereby aligning the position of the paper K with the position of the toner image.

[0146] In the secondary transfer section 20, the secondary transfer roll 22 is pressed against the back roll 25 via the intermediate transfer belt 15. At this time, the paper K, which has been transported in time, is sandwiched between the intermediate transfer belt 15 and the secondary transfer roll 22. At this time, when a voltage (secondary transfer bias) of the same polarity as the charging polarity (negative polarity) of the toner is applied from the power supply roll 26, a transfer electric field is formed between the secondary transfer roll 22 and the back roll 25. Then, the unfixed toner images held on the intermediate transfer belt 15 are electrostatically transferred collectively onto the paper K in the secondary transfer section 20, which is pressed by the secondary transfer roll 22 and the back roll 25.

[0147] Thereafter, the paper K onto which the toner image has been electrostatically transferred is transported as it is after being peeled off from the intermediate transfer belt 15 by the secondary transfer roll 22, and is transported to a transport belt 55 provided downstream of the secondary transfer roll 22 in the paper transport direction. The transport belt 55 transports the paper K to the fixing device 60 at an optimal transport speed for the fixing device 60. The unfixed toner image on the paper K transported to the fixing device 60 is fixed onto the paper K by being subjected to a fixing process using heat and pressure by the fixing device 60. The paper K on which the fixed image has been formed is then transported to an ejected paper storage section (not shown) provided in the ejection section of the image forming apparatus.

[0148] On the other hand, after the transfer to the paper K is completed, the residual toner remaining on the intermediate transfer belt 15 is transported to the cleaning section as the intermediate transfer belt 15 rotates, and is removed from the intermediate transfer belt 15 by the cleaning back roll 34 and the intermediate transfer belt cleaner 35. Through the above steps, an image is formed on paper K as a recording medium by image forming apparatus 100. EXAMPLES

[0149] The present embodiment will be specifically described below with reference to examples, but the present embodiment is not limited to the examples shown below.

[0150] [Making endless belts] <Example 1> (Metal substrate) An endless SUS substrate with a thickness of 50 μm, an inner diameter of 30 mm, and a length of 360 mm was prepared as the metal substrate. The thermal conductivity of the SUS substrate was 40 W / mK.

[0151] (Formation of heat-resistant resin layer) As the thermally conductive filler, carbon nanotubes (CNTs) (VGCF-H, manufactured by Showa Denko KK, average outer diameter: 150 nm, average length: 6 μm, aspect ratio: 40, thermal conductivity: 1200 W / mK) were prepared.

[0152] The above carbon nanotubes were added in an amount of 14 parts by mass per 100 parts by mass of resin solids to an N-methyl-2-pyrrolidone (NMP) solution (solids concentration: 22% by mass) of polyamic acid consisting of 3,3',4,4'-biphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether, and the mixture was mixed and roughly dispersed in a planetary mixer (Aikosha Seisakusho Co., Ltd.) and then dispersed using a jet mill to prepare coating liquid 1 for forming a heat-resistant resin layer.

[0153] While rotating the metal substrate, the coating liquid 1 for forming a heat-resistant resin layer was applied to the inner peripheral surface of the metal substrate by spiral coating. The coating conditions were a rotation speed of the metal substrate: 100 (unit: rpm), and a moving speed of the discharge part in the direction of the rotation axis of the metal substrate: 1000 (unit: mm / s). The discharge amount of the coating liquid for forming a heat-resistant resin layer per unit time was 1.5 (unit: g / 10s) at the end of the rotation axis direction of the metal substrate, gradually decreasing from the end toward the center, and was 0.8 (unit: g / 10s) at the center. Thereafter, while the metal substrate was kept horizontal, it was heated and dried at 140° C. for 30 minutes, and then heated at 320° C. for 1 hour to imidize the polyamic acid.

[0154] In this manner, a heat-resistant resin layer containing polyimide as the resin and carbon nanotubes as the thermally conductive filler was formed. Table 1 shows the orientation rate (circumferential direction) A of the thermally conductive filler in the obtained heat-resistant resin layer ("Orientation rate A circumferential" in Table 1), orientation rate (width direction) B ("Orientation rate B width" in Table 1), average thickness, thickness at the center of the endless belt in the width direction ("Center thickness" in Table 1), thickness at the ends of the endless belt in the width direction ("End thickness" in Table 1), arithmetic mean roughness Ra in the width direction of the endless belt on the inner surface, and average spacing Sm of irregularities in the width direction of the endless belt on the inner surface.

[0155] (Formation of Elastic Layer and Release Layer) A liquid silicone rubber (KE1940-35, liquid silicone rubber 35 degrees, manufactured by Shin-Etsu Chemical Co., Ltd.) adjusted to have a hardness of 35 degrees as specified by JIS Type A was applied to the outer peripheral surface of the metal substrate to a film thickness of 200 μm and then dried to obtain an elastic layer. Next, a PFA dispersion (dispersion of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, 500 cL, manufactured by Mitsui DuPont Fluorochemicals) was applied to the outer surface of the obtained elastic layer to a film thickness of 30 μm, and baked at 380 degrees to form a release layer. In this manner, an endless belt 1 was obtained.

[0156] <Example 2> In forming the heat-resistant resin layer, the coating conditions for the coating liquid for forming a heat-resistant resin layer were as follows: rotation speed of the metal substrate: 60 (unit: rpm), movement speed of the discharge part in the rotation axis direction of the metal substrate: 800 (unit: mm / s), and discharge amount of the coating liquid for forming a heat-resistant resin layer per unit time was 1.5 (unit: g / 10 s) at the end part in the rotation axis direction of the metal substrate and gradually decreased from the end part toward the center, to 0.8 (unit: g / 10 s) at the center, in the same manner as in Example 1, to obtain an endless belt 2.

[0157] <Example 3> An endless belt 3 was obtained in the same manner as in Example 1, except that in the preparation of the heat-resistant resin layer-forming coating liquid, 20 parts by mass of carbon nanotubes were added per 100 parts by mass of the resin solid content.

[0158] <Example 4> An endless belt 4 was obtained in the same manner as in Example 1, except that in the preparation of the heat-resistant resin layer-forming coating liquid, 10 parts by mass of carbon nanotubes were added per 100 parts by mass of the resin solid content.

[0159] <Example 5> An endless belt 5 was obtained in the same manner as in Example 1, except that in preparing the coating liquid for forming a heat-resistant resin layer, carbon nanotubes (CNTs) (VGCF-S, manufactured by Showa Denko, average outer diameter: 80 nm, average length: 100 μm, aspect ratio: 1250, thermal conductivity: 1000 w / mK) were used as the conductive filler.

[0160] <Example 6> In forming the heat-resistant resin layer, the coating conditions for the coating liquid for forming the heat-resistant resin layer were such that the discharge amount of the coating liquid for forming the heat-resistant resin layer per unit time was constant at 1.6 (unit: g / 10 s) from the end portion in the rotational axis direction of the metal substrate to the center portion, and the same procedure was followed as in Example 1 to obtain an endless belt 6.

[0161] <Comparative Example 1> In forming the heat-resistant resin layer, the above-mentioned coating liquid 1 for forming a heat-resistant resin layer was used, and the coating liquid 1 for forming a heat-resistant resin layer was applied to the inner surface of the metal substrate by a dip coating method, by pulling the metal substrate in the axial direction, thereby obtaining an endless belt C1 in the same manner as in Example 1.

[0162] <Comparative Example 2> An endless belt C2 was obtained in the same manner as in Example 1, except that the carbon nanotubes were not added in the preparation of the heat-resistant resin layer-forming coating liquid.

[0163] [Evaluation of endless belts] <Thermal conductivity on the inner surface of the endless belt> The thermal conductivity of the inner peripheral surface of the obtained endless belt (i.e., the thermal conductivity of the entire heat-resistant resin layer) was measured using a thermal conductivity measuring device (ai-Phase Mobile manufactured by Ai-Phase Corporation) in accordance with ISO 22007-6 by the AC steady-state method. A higher thermal conductivity value obtained by the measurement means higher thermal conductivity of the inner peripheral surface of the endless belt. The results are shown in Table 1.

[0164] <Sliding resistance on the inner surface of the endless belt> Using a friction and wear tester (FPR-2100, manufactured by Rhesca Co., Ltd.), the obtained endless belt was placed on a 150°C heating stage so that the inner peripheral surface of the endless belt was in contact with a pin (material: SUS), and three loads of 10g, 20g, and 30g were applied. The dynamic friction coefficient was measured for each load by a linear reciprocating sliding measurement method with a measurement length of 50mm and a measurement speed of 25mm / sec, and the average value was calculated. The smaller the average value of the dynamic friction coefficient calculated by the measurement, the more reduced the sliding resistance on the inner peripheral surface of the endless belt. The results are shown in Table 1.

[0165] [Table 1]

[0166] It was found that the endless belt of the example had reduced sliding resistance on the inner peripheral surface while achieving high thermal conductivity on the inner peripheral surface, compared to the endless belt of the comparative example. [Explanation of symbols]

[0167] 1Y, 1M, 1C, 1K Image forming unit 10 Primary transfer section 11 Photoconductor (an example of an image carrier) 12 Charger (an example of a charging device) 13 Laser exposure device (an example of a latent image forming device) 14 Developing unit (an example of a developing device) 15 Intermediate transfer belt 16 Primary transfer roll 17 Photoconductor cleaner 20 Secondary transfer section 22 Secondary transfer roll 25 Back roll 26 Power supply roll 31 Driving Roll 32 Support roll 33 Tensioning roll 34 Cleaning back roll 35 Intermediate transfer belt cleaner 40 Control section 42 Reference Sensor 43 Image density sensor 50 Paper storage section 51 Paper feed roll 52 Transport roll 53 Transport guide 55 Conveyor belt 56 Fixing entrance guide 60 Fixing device 62 Fixing belt (an example of a first rotating body) 62A, 62B, 62C, 72A, 72B, 72C Rotating support roll 64 Pressure roll (an example of a second rotating body) 66 Pressure pad (an example of a pressing member) 68 Halogen lamp (an example of a heat source) 70 Reflector 72 Recording medium transport belt (an example of a second rotating body) 74 Linear heating element (an example of a pressing member and a heating source) 74A Pulse current supply 76 Heat sink 80 Fixing device 100 Image forming device 110 Endless Belt 120 Metallic substrate 130 Heat-resistant resin layer 140 Elastic layer 150 Release layer Bm Exposure Beam N contact area K Paper

Claims

1. A metal substrate; a heat-resistant resin layer provided as an innermost layer on an inner circumferential surface of the metal substrate, the heat-resistant resin layer including a resin and a heat-conductive filler having an aspect ratio of 20 or more, the heat-conductive filler having an orientation rate of 20% or more in the circumferential direction of the endless belt; An endless belt having

2. 2. The endless belt according to claim 1, wherein the thermally conductive filler is a carbon-based filler.

3. 3. The endless belt according to claim 2, wherein the carbon-based filler is a carbon nanotube.

4. 4. The endless belt according to claim 1, wherein a thermal conductivity ratio between the metal substrate and the thermally conductive filler (metal substrate / thermally conductive filler) is 1 / 100 or more and 1 / 3 or less.

5. 5. The endless belt according to claim 4, wherein the thermal conductivity of the thermally conductive filler is 200 W / mK or more and 1500 W / mK or less.

6. 6. The endless belt according to claim 1, wherein an orientation rate of the thermally conductive filler in the width direction of the endless belt is 20% or more and 80% or less.

7. 7. The endless belt according to claim 1, wherein the heat-resistant resin layer has a thickness that gradually increases from a central portion toward each end in the width direction of the endless belt.

8. A first rotating body formed of the endless belt according to any one of claims 1 to 7; A second rotating body disposed in contact with an outer circumferential surface of the first rotating body; a pressing member disposed inside the first rotating body and pressing the first rotating body against the second rotating body from an inner circumferential surface of the first rotating body; A fixing device comprising:

9. An image carrier; a charging device for charging the surface of the image carrier; a latent image forming device for forming a latent image on the charged surface of the image carrier; a developing device for developing the latent image with toner to form a toner image; a transfer device for transferring the toner image onto a recording medium; a fixing device according to claim 8 for fixing the toner image onto a recording medium; An image forming apparatus comprising:

Images