Fixing member, fixing device, and image forming apparatus

Abstract

An object of the present invention is to provide a fixing member containing no fluorine compound and capable of suppressing release of UFPs to the outside while maintaining separability. The fixing member includes a base layer, an elastic layer laminated on the base layer, an intermediate layer laminated on the elastic layer and including a first resin and no fluorine compound, and a surface layer laminated on the intermediate layer and including a second resin and no fluorine compound. The intermediate layer has an oxygen permeability of 3500 mL / (m2·24hrs·atm) or less at 25°C.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention

[0001] The present invention relates to a fixing member, a fixing device, and an image forming apparatus.2. Description of Related Art

[0002] In the related art, an electrophotographic image forming apparatus such as a copying machine, a laser beam printer, or the like includes a fixing device that fixes a toner image to a recording medium by bringing a heated fixing member into contact with an unfixed toner image carried on the recording medium (for example, refer to PTL 1). Such a fixing device is configured to thermally press a toner image onto a conveyed recording medium and to peel the recording medium from the fixing member. Furthermore, the fixing member is required to have a surface that is not contaminated with toner or wax and to be made of a material having a high melting point in order to melt toner on the surface of the fixing member.

[0003] PTL 1 describes a fixing device including a fixing member, a pressure roller, a fixing belt, an excitation coil, and a demagnetization coil. The fixing belt in the fixing device described in PTL 1 includes a base material layer, an elastic layer made of silicone rubber, and a barrier layer made of fluororesin. In the fixing device described in PTL 1, the fixing belt has an outermost layer containing a fluororesin, thereby exhibiting the above-described function.Citation ListPatent Literature

[0004] PTL 1 Japanese Unexamined Patent Publication No. 2016-18015SUMMARY OF THE INVENTION

[0005] In PTL 1, since the elastic layer of the fixing belt is formed of silicone rubber, particles (Ultra - Fine Particles: UFP) having a diameter in the range of 1.3 to 3.0 nm or less may be generated during fixing of the toner. Further, since the fluorine resin of the outermost layer is chemically very stable, it remains semi-permanently even after the product's lifespan has ended. In addition, some fluororesins areof concern due to their potential for bioaccumulation and toxicity to the human body. In Europe and the like, the regulation of PFAS (Per and Polyfluoroalkylsubstances), which is a general term for organic fluorine resins, is advancing, and it is considered that the regulation on the use of organic fluorine resins will be further strengthened in the future. Therefore, it is desired to use a fixing member using a resin which is not a fluororesin.

[0006] An object of the present invention is to provide a fixing member containing no fluorine compound and capable of suppressing release of UFPs to the outside while maintaining separability. Another object of the present invention is to provide a fixing device and an image forming apparatus each including the fixing member.Solution to Problem

[0007] A fixing member according to one embodiment of the present invention includes a base layer; an elastic layer laminated on the base layer; an intermediate layer laminated on the elastic layer, the intermediate layer including a first resin and not including a fluorine compound; and a surface layer laminated on the intermediate layer, the surface layer including a second resin and not including a fluorine compound; in which the intermediate layer has an oxygen permeability of 3500 mL / (m 2< ·24hrs·atm) or less at 25°C.

[0008] A fixing device according to one embodiment of the present invention includes the fixing member of the present invention; a plurality of rollers that axially support the fixing member; and a heater for heating the fixing member.

[0009] An image forming apparatus according to embodiment of the present invention includes the fixing device of the present invention, in which an unfixed toner image formed on a recording medium by an electrophotographic method is fixed to the recording medium by heating and pressurizing.BRIEF DESCRIPTION OF DRAWING

[0010] The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention: Fig. 1 is a diagram illustrating a configuration of an image forming apparatus according to Embodiment 1 of the present invention; Fig. 2 is a diagram illustrating a configuration of a fixing device according to Embodiment 1 of the present invention; Figs. 3A and B are diagrams illustrating a configuration of a fixing member according to Embodiment 1 of the present invention; and Fig. 4 is a diagram illustrating a configuration of a fixing device according to Embodiment 2 of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.[Embodiment 1](Configuration of Image Forming Apparatus and Fixing Device)

[0012] Fig. 1 is a diagram illustrating a configuration of an image forming apparatus 10 according to Embodiment 1 of the present invention. Fig. 2 is a diagram illustrating a configuration of a fixing device 60 according to Embodiment 1 of the present invention.

[0013] As illustrated in Fig. 1, the image forming apparatus 10 includes an image reading section 20, an image forming section 30, an intermediate transfer section 40, a fixing device 60, and a recording medium conveyance section 80.

[0014] The image reading section 20 reads an image from a document D and obtains image data for forming an electrostatic latent image. The image reading section 20 includes a sheet feed device 21, a scanner 22, a CCD sensor 23, and an image processing section 24.

[0015] The image forming section 30 includes, for example, four image forming units 31 corresponding to respective colors of yellow, magenta, cyan, and black. Each image forming unit 31 includes a photosensitive drum 32, a charging device 33, an exposure device 34, a developing device 35, and a cleaning device 36.

[0016] The photosensitive drum 32 is, for example, a negatively charged organic photosensitive member having photoconductivity. The charging device 33 charges the photosensitive drum 32. The charging device 33 is, for example, a corona charger. The charging device 33 may be a contact charging device that brings a contact charging member, such as a charging roller, a charging brush, or a charging blade, into contact with the photosensitive drum 32 to charge the photosensitive drum 32. The exposure device 34 irradiates the charged photoconductor drum 32 with light to form an electrostatic latent image. The exposure device 34 is, for example, a semiconductor laser. The developing device 35 supplies toner to the photoconductor drum 32 on which an electrostatic latent image is formed to form a toner image corresponding to the electrostatic latent image. The developing device 35 is, for example, a known developing device in an electrophotographic image forming apparatus. The cleaning device 36 removes residual toner on the photosensitive drum 32. Here, the "toner image" refers to a state in which toner is aggregated in the form of an image.

[0017] As the toner, a known toner can be used. The toner may be a mono-component developer or a two component developer. The mono-component developer is composed of toner particles. Two component developer is composed of toner particles and carrier particles. The toner particles each include a toner base particle and an external additive, such as silica, adhering to the surface of the toner mother particle. The toner base particles are composed of, for example, a binder resin, a colorant, and a wax.

[0018] The intermediate transfer section 40 includes a primary transfer unit 41 and a secondary transfer unit 42.

[0019] The primary transfer unit 41 includes an intermediate transfer belt 43, a primary transfer roller 44, a backup roller 45, a plurality of first support rollers 46, and a cleaning device 47. The intermediate transfer belt 43 is an endless belt. The intermediate transfer belt 43 is stretched by the backup roller 45 and the first support rollers 46. When at least one of the backup roller 45 and the first support rollers 46 is driven to rotate, the intermediate transfer belt 43 travels on the endless track in one direction at a constant speed.

[0020] The secondary transfer unit 42 includes a secondary transfer belt 48, a secondary transfer roller 49, and a plurality of second support rollers 50. The secondary transfer belt 48 is an endless belt. The secondary transfer belt 48 is stretched by the secondary transfer roller 49 and the second support rollers 50.

[0021] As illustrated in Fig. 2, the fixing device 60 fixes an unfixed toner image formed on a recording medium S by an electrophotographic method to the recording medium S by heating and pressing. The fixing device 60 includes a fixing member 61, a heating roller 62, a first pressure roller 63, a second pressure roller 64, heaters (heating sections) 65 and 66, a first temperature sensor 67, a second temperature sensor 68, an airflow separation device 69, a guide plate 70, and a guide roller 71.

[0022] The shape of the fixing member 61 is not particularly limited as long as the fixing device 60 can exert the above-described function. Examples of the shape of the fixing member 61 include an endless belt shape, a roller shape, and a plate shape. In the present embodiment, the fixing member 61 has an endless belt shape. In the fixing member 61, a base layer 61a, an elastic layer 61b, an intermediate layer 61c, and a surface layer 61d are laminated in this order (see Figs. 3A and 3B). The fixing member 61 is axially supported by two or more rollers in a state in which the base layer 61a is on the inner side and the surface layer 61d is on the outer side. In the present embodiment, the fixing member 61 is rotatably supported by the heating roller 62 and the first pressure roller 63, which are axially supported. The tensile force of the fixing member 61 is preferably 45 N or less. When the tensile force of fixing member 61 exceeds 45 N, first pressure roller 63 may be damaged. The tensile force of the fixing member 61 is, for example, 43 N.

[0023] The heating roller 62 includes a rotatable sleeve made of aluminum and a heater 65 disposed therein. The type of the heater 65 is not particularly limited. Examples of the type of the heater 65 include a halogen heater (halogen heater type) and an electromagnetic induction coil (IH type). In the present embodiment, the heater 65 is a halogen heater disposed inside the heating roller 62. The first pressure roller 63 includes, for example, a rotatable core metal and an elastic layer disposed on an outer peripheral surface of the core metal.

[0024] The second pressure roller 64 is disposed to face the first pressure roller 63 via the fixing member 61. The second pressure roller 64 includes, for example, a rotatable aluminum sleeve and a heater 66 disposed in the sleeve. The second pressure roller 64 is positioned so as to be able to approach and move away from the first pressure roller 63. When the second pressure roller 64 approaches the first pressure roller 63, the second pressure roller 64 presses the elastic layer of the first pressure roller 63 via the fixing member 61 to form a fixing nip portion which is a contact portion with the fixing member 61. The outer diameter of the second pressure roller 64 is preferably 50 mm or more. When the outer diameter of the second pressure roller 64 is less than the 50 mm, a satisfactory thermal capacity of the roller cannot be achieved, and the printing speed of the image forming apparatus 10 cannot be increased. The type of the heater 66 is not particularly limited. Examples of the type of the heater 66 include a halogen heater and an electromagnetic induction coil. In the present embodiment, the heater 66 is a halogen heater disposed inside the heating roller 62.

[0025] The first temperature sensor 67 is a device for detecting the temperature of the fixing member 61 heated by the heating roller 62. The second temperature sensor 68 is a device for detecting the temperature of the outer peripheral surface of the second pressure roller 64.

[0026] The airflow separation device 69 is a device for generating an airflow from the downstream side in the moving direction of the fixing member 61 toward the fixing nip portion and promoting separation of the recording medium (standard paper, special paper, or the like in the present embodiment) S from the fixing member 61.

[0027] The guide plate 70 is a member for guiding a recording medium S having an unfixed toner image to the fixing nip portion. The guide roller 71 is a member for guiding the recording medium S, on which the toner image has been fixed, from the fixing nip portion to the outside of the image forming apparatus 10.

[0028] The recording medium conveyance section 80 includes three sheet feed tray units 81 and a plurality of registration roller pairs 82. In the sheet feeding tray unit 81, the recording media S identified based on a basis weight, a size, or the like is accommodated for each type set in advance. The registration roller pairs 82 are disposed so as to form an intended conveyance path.

[0029] In such an image forming apparatus 10, at the intermediate transfer portion 40, a toner image is formed on on the recording medium S sent by the recording medium conveyance section 80, based on the image data acquired by the image reading section 20 . The recording medium S on which the toner image has been formed by the intermediate transfer section 40 is sent to the fixing device 60.

[0030] The fixing member 61 in the fixing device 60 is rotationally driven at a predetermined speed, and is heated to a desired temperature (for example, 190°C) by the heater 65 under feedback control by the first temperature sensor 67, for example. The second pressure roller 64 is heated to a desired temperature (for example, 180°C) by the heater 66 under feedback control of the second temperature sensor 68, for example. In synchronization with the arrival of the recording medium S, the second pressure roller 64 biases the outer peripheral surface of the first pressure roller 63 via the fixing member 61 to form a fixing nip portion.

[0031] On the other hand, the recording medium S bearing an unfixed toner image is guided to the fixing nip portion while being guided by the guide plate 70. Next, the fixing member 61 comes into close contact with the recording medium S, so that the unfixed toner image is quickly fixed onto the recording medium S. Further, the recording medium S receives the airflow from the airflow separation device 69 at the downstream end of the fixing nip portion. Therefore, separation of the recording medium S from the fixing member 61 is promoted. The recording medium separated from the fixing member 61 is guided toward the outside of the image forming apparatus 10 by the guide roller 71.(Configuration of Fixing Member)

[0032] Next, the fixing member 61 will be described in detail. Fig. 3A is a perspective view of the fixing member 61, and Fig. 3B is an enlarged view of a region A illustrated in Fig. 3A.

[0033] As illustrated in Figs. 3A and B, the fixing member 61 includes a base layer 61a, an elastic layer 61b, an intermediate layer 61c, and a surface layer 61d. In the fixing member 61, the base layer 61a is disposed on the inner side, and the surface layer 61d is disposed on the outer side.

[0034] The base layer 61a is made of heat-resistant resin. The heat-resistant resin can be appropriately selected from resins that are not denatured or deformed within the range of the use temperature of the fixing member 61. Examples of the heat-resistant resin include polyimide, polyphenylene sulfide, polyarylate, polysulfone, polyethersulfone, polyetherimide, polyamide-imide, and polyether ether ketone. The heat-resistant resin is preferably polyimide from the viewpoint of heat resistance. The heat-resistant resin may be used alone or in combination of two or more kinds thereof.

[0035] Polyimide is obtained by heating polyamic acid, the precursor thereof, at a temperature of 200°C or higher, or by promoting dehydration and cyclization (imidization) reactions of polyamic acid with the use of a catalyst. The polyamic acid may be produced by dissolving a tetracarboxylic dianhydride and a diamine compound in a solvent, followed by mixing and heating for polycondensation reaction, or a commercially available product may be used. Examples of the diamine compound and the tetracarboxylic dianhydride include compounds described in paragraphs 0123 to 0130 of Japanese Unexamined Patent Publication No. 2013-25120.

[0036] The base layer 61a may further include components other than the heat-resistant resins to the extent that the effects of the present embodiment are achieved. The content of the heat-resistant resin in the material of the base layer 61a is preferably within a range of 40 to 100 vol% from the viewpoint of moldability and the like.

[0037] The elastic layer 61b is made of a heat-resistant elastic material. The elastic layer 61b is disposed on the base layer 61a. Examples of the material of the elastic layer 61b include elastic resin materials such as silicone rubber, thermoplastic elastomer, and rubber materials. The material of the elastic layer 61b is preferably silicone rubber.

[0038] Examples of the silicone rubber include polyorganosiloxane or a heat-cured product thereof, and addition reaction type silicone rubber described in Japanese Unexamined Patent Publication No. 2009-122317. Examples of the polyorganosiloxane include a dimethylpolysiloxane capped at both ends thereof with trimethylsiloxane groups and a having vinyl group in the side chain, which is described in paragraph 0029 of Japanese Unexamined Patent Publication No. 2008-255283. The silicone rubber may be used alone, or in combination of two or more kinds thereof.

[0039] The content of the elastic resin material in the elastic material is preferably within a range of 60 to 100 vol%, more preferably within a range of 75 to 100 vol%, and still more preferably within a range of 80 to 100 vol%.

[0040] The thickness of the elastic layer 61b is, for example, preferably in a range of 30 to 400 µm, more preferably in a range of 50 to 300 µm, and still more preferably in a range of 100 to 250 µm, from the viewpoint of sufficiently exhibiting thermal conductivity and resilience.

[0041] The elastic layer 61b may further include a component other than the elastic resin material to the extent that the effect of the present embodiment is achieved. For example, the elastic material may further include a thermally conductive filler for enhancing the thermal conductivity of the elastic layer. Examples of filler materials include silica, metallic silica, alumina, zinc, aluminum nitride, boron nitride, silicon nitride, silicon carbide, carbon, and graphite. The form of the filler is not limited, and for example, it is a spherical powder, an amorphous powder, a flat powder or a fiber.

[0042] The intermediate layer 61c suppresses release of UFPs generated from the elastic layer 61b to the outside during use. The intermediate layer 61c is laminated on the elastic layer 61b. The intermediate layer 61c includes a first resin and does not include a fluorine compound. Examples of the first resin include polyimide, polymethylpentene, and polyethylene. The first resin of the intermediate layer 61c is preferably polyimide.

[0043] Examples of the fluorine compound that cannot be contained in the intermediate layer 61c include a perfluoropolymer having a fluorine-containing aliphatic ring structure in the main chain, a fluoropolymer obtained by copolymerization of a monomer having a methylene group in the molecule and a highly fluorinated monomer, and a fluoropolymer in which a crystalline fluorine-containing segment is graft-polymerized to the main chain having the same configuration as the fluorine-containing elastomer. Examples of the copolymerization component of a fluorine compound include perfluorovinyl monomers such as tetrafluoroethylene (TFE), hexafluoropropylene (HFP), vinylidene fluoride (VDF), and perfluoroalkyl vinyl ethers. Specific examples of the fluorine compound include polytetrafluoroethylene (PTFE), perfluoroalkoxy fluororesin (PFA), a copolymer of tetrafluoroethylene and ethylene (ETFE), and polyvinylidene fluoride (PVDF).

[0044] The intermediate layer 61c has an oxygen permeability of 3500 mL / (m 2< ·24 hrs·atm) or less, more preferably 2000 mL / (m 2< ·24 hrs·atm) or less. In a case where the oxygen permeability exceeds 3500 mL / (m 2< ·24 hrs·atm), it is not possible to suppress release of UFPs generated from the elastic layer 61b to the outside.

[0045] The oxygen permeability of the intermediate layer 61c can be measured by, for example, the following method. First, the interlayer 61c (50 cm 2< ) is attached to a test cell. While maintaining the test cell at 25°C, oxygen having a stable relative humidity is allowed to flow on one side of the intermediate layer 61c, and high-purity nitrogen is allowed to flow on the other side of the intermediate layer 61c. At this time, oxygen permeates the intermediate layer 61c and permeates from the one side to the other side. The oxygen permeating into the nitrogen side is measured with an oxygen / water vapor transmission rate measurement device (C406H; Labthink). Through the above steps, the oxygen permeability of the intermediate layer 61c can be measured.

[0046] The method of adjusting the oxygen permeability of the intermediate layer 61c is not particularly limited. Examples of methods for adjusting the oxygen permeability of the intermediate layer 61c include a method for controlling the degree of crystallinity of a polymer forming the first resin .

[0047] Here, the relationship between the oxygen permeability and the suppression of the release of UFPs to the outside will be described. As described above, UFP means particles having a diameter in a range of 1.3 to 3.0 nm or less. On the other hand, oxygen molecules have a diameter of about 0.34 nm. That is, oxygen molecules are significantly smaller than UFPs. Therefore, when the fixing member 61 includes the intermediate layer 61c having the holes of the size that does not allow the oxygen molecules to pass therethrough, the UFPs larger than the oxygen molecules cannot pass through the fixing member 61. Therefore, whether or not the release of UFP to the outside can be suppressed is defined by defining the oxygen permeability.

[0048] The thickness of the intermediate layer 61c is, for example, preferably within a range of 1 to 20 µm, and more preferably within a range of 5 to 10 µm.

[0049] The tensile strength of the intermediate layer 61c is preferably equal to or more than 20 MPa and preferably equal to or more than 40 MPa. When the tensile strength is less than 20 MPa, the fixing member 61 may be damaged. The tensile strength of the intermediate layer 61c can be measured with a Tensilon universal tensile tester (A & D Co., Ltd).

[0050] The melting point of the intermediate layer 61c (first resin) is preferably 200°C or more and more preferably 220°C or more. In a case where the tensile strength is less than 20 MPa, the layer cannot withstand the temperature at the time of use and may be melted. The melting points of the intermediate layer 61c (first resin) can be confirmed from their melting peaks when measured at 2°C / min with a differential scanning calorimeter (DSC-60, Shimadzu Corporation).

[0051] The surface layer 61d has moderate releasability from toner. The surface layer 61d is disposed on the intermediate layer 61c. The surface layer 61d contains a second resin and does not contain a fluorine compound. Examples of the second resin include silicone resins and polymethylpentene.

[0052] Examples of the fluorine compound that cannot be contained in the surface layer 61d include the same fluorine compounds as the fluorine compounds that cannot be contained in the intermediate layer 61c.

[0053] The thickness of the surface layer 61d is, for example, preferably within a range of 10 to 50 µm and more preferably within a range of 15 to 30 µm from the viewpoints of the heat conductivity, the followability to deformation of the elastic layer 61b, and the exhibition of the releasability.

[0054] The hexadecane contact angle of the surface layer 61d at 150°C is preferably more than 25°. When the hexadecane contact angle is 25° or less, the releasability from the recording medium S may be deteriorated.

[0055] The hexadecane contact angle can be measured, for example, by the following method. The hexadecane contact angle was measured using an automatic contact-angle meter (Dmo-602; Kyowa Interface Science Co., Ltd) under an environment of 150°C, with n-hexadecane used as the contact angle measurement liquid, 2 µL of which was dropped onto the surface of surface layer 61d, and the hexadecane contact angle was measured after 5 seconds.

[0056] The fixing member 61 may further include a layer other than the base layer 61a, the elastic layer 61b, the intermediate layer 61c, and the surface layer 61d described above as long as the effect of the present embodiment can be obtained. Examples of the other layers include a reinforcing layer.

[0057] The reinforcing layer is a layer for increasing the mechanical strength of the fixing member 61, and is disposed, for example, on the surface (the inner peripheral surface of the base layer 61a) of the fixing member 61 opposite to the surface layer 61d. The reinforcing layer may be formed of the above-described heat-resistant resin, and the thickness thereof may be appropriately determined.

[0058] Although it is specified in the above description that the intermediate layer 61c and the surface layer 61d do not contain a fluorine compound, in the present embodiment, none of the constituent elements of the fixing member 61 contains a fluorine compound. Examples of the fluorine compound not contained are the same as the examples of the fluorine compound not contained in the intermediate layer 61c and the surface layer 61d.

[0059] The fixing member 61 according to the present embodiment can be produced using a known method for producing a laminated fixing belt. The method of manufacturing the fixing member 61 includes a step of covering the outer surface of the endless heat-resistant resin-made base layer 61a with a tube that will serve as the intermediate layer 61c, a step of injecting an elastic material or a precursor thereof between the molded body and the tube, a step of heating and curing the elastic material or the precursor as necessary, and a step of forming the surface layer 61d on the surface of the intermediate layer 61c.(Effect)

[0060] As described above, since the fixing member 61 according to the present embodiment includes the intermediate layer 61c that does not include a fluorine compound, it is possible to suppress the release of UFPs to the outside while maintaining the separability.[Second Embodiment]

[0061] Next, an image forming apparatus according to Embodiment 2 will be described. The image forming apparatus of the present embodiment is different from the image forming apparatus 10 of Embodiment 1 only in the configuration of the fixing device 60. Therefore, a configuration the same as that of Embodiment 1 is denoted by the same reference sign, and a description thereof is omitted.

[0062] Fig. 4 is a schematic diagram illustrating a configuration of the fixing device 60 in the image forming apparatus according to Embodiment 2. As illustrated in Fig. 4, the fixing device 60 according to the present embodiment includes a fixing member 61, a heating roller 62 and a first pressure roller 63, a second pressure roller 64, a heater (heating section) 65, a first temperature sensor 67, a second temperature sensor 68, an airflow separation device 69, a guide plate 70, and a guide roller 71.

[0063] The heater (heating section) 65 in the present embodiment is a heat source (SURF system) disposed on the back side of the fixing member 61. The fixing member 61 may have a roller shape or a plate shape.(Effect)

[0064] As described above, the fixing member 61 according to the present embodiment has an effect similar to that of Embodiment 1.Examples

[0065] The present invention will be described more specifically with reference to the following Examples and Comparative Examples. Hereinafter, unless otherwise specified, each operation was performed at room temperature (20°C). Note that the present invention is not limited to the following examples.

[0066] [Example 1] Polyimide (Upilex S; UBE Industries, Ltd) was applied to the outside of the cylindrical mold while the cylindrical mold was rotated. Next, the polyimide tubular product (base layer) having a cylindrical shape and a thickness of 70 µm was obtained by drying and imidizing at 250 to 450°C.

[0067] Next, polyimide (Upilex S; UBE Industries, Ltd) was applied to the outside of the base layer and the inside of the cylindrical mold. Next, the applied polyimide was dried at 250 to 450°C and imidized to obtain a cylindrical polyimide tubular product (intermediate layer) having a thickness of 10 µm.

[0068] Next, a silicone rubber material (X-34-2888; Shin - Etsu Chemical Co., Ltd) was injected into a gap between the base layer and the intermediate layer and was cured by heating to obtain a silicone rubber tubular product (elastic layer) having a thickness of 200 µm.

[0069] Next, silicone resin (SR2361 Dow Toray Co., Ltd) was applied onto the intermediate layer to obtain a 20 µm-thick silicone tubular product (surface layer).

[0070] Through the above steps, a fixing belt 1 of Example 1 including the elastic layer (silicone rubber tubular product), the polyimide tubular product (intermediate layer), and the silicone tubular product (surface layer) on the base layer (polyimide tubular product) was obtained.

[0071] [Examples 2 to 4 and Comparative Example 1] Fixing belts 2 to 5 of Examples 2 to 4 and Comparative Example 1 were obtained in the same manner as the fixing belt 1 except that the components and the ratios were changed as described in Table 1.

[0072] [Comparative Example 2] A fixing belt 6 of Comparative Example 2 was obtained in the same manner as the fixing belt 1 except that the component was changed as described in Table 1 and the intermediate layer was not formed.

[0073] In Table 1, MX002 and DX845 (Mitsui Chemicals, Inc) are polymethylpentene. UHMW-PE (Mitsui Chemicals, Inc) is polyethylene. TK-2500PE (Shin-Etsu Chemical Co., Ltd) is polyvinylchloride.

[0074] The hexadecane contact angle of each fixing belt at 150°C was measured by the above-described method. The tensile strength of each intermediate layer was 20 MPa or more. The intermediate layers of the fixing belts 1 to 3, 5, and 6 each had a melting point of 200°C or higher. The melting point of the intermediate layer of the fixing belt 4 was 150°C.

[0075] [Evaluation of Separability] An image forming apparatus was prepared in which the fixing device including each of the produced fixing belts was mounted as the fixing device in a full color production printer (Accurio Press C3070; Konica Minolta Inc). Using each image forming apparatus, a cyan and magenta two layer solid image (red) having an arbitrary margin in 1 mm increments at the leading edge of the image was outputted as an outputted image, using color copy sheet (basis weight 90 / m 2< mondi Co., Ltd) as A4 plain paper, and the state of sheet passing of the color copy sheet was visually observed, with the separation air volume throttled to 30% of the setting. The separability was evaluated according to the following criteria. A: The plain paper was separated without curling. B: The plain paper curled a little, but there was no problem. C: The plain paper could not be separated.

[0076] [Evaluation of UFPs] Each fixing belt (diameter 100 mm, length 400 mm) was placed in a metal tube having a diameter of 200 mm, a length of 500 mm, and an air vent (diameter 20 mm) to the outside.

[0077] The metal tube was heated to 200°C while nitrogen was allowed to flow through the metal tube at 2 liters / min. The number of UFPs in the outflowing air was measured with an ultrafine particle counter (P-TRAK; Transtec Corporation). The UFPs were evaluated according to the following criteria. A: The number of UFPs was less than 200000 / cc. B: The number of UFPs was 200000 or more and 400000 / cc or less. C: The number of UFPs was more than 400000 pcs / cc.

[0078] Table 1 shows the configuration and physical properties of each fixing belt and the evaluation results. [Table 1]Base layerElastic layerIntermediate layerSurface layerContact angle (°C)Evaluation resultResin typeProduct nameResin typeProduct nameResin typeProduct nameOxygen permeability mL / (m 2< ·24hrs·atm)Resin typeProduct nameSeparabilityUFPExample 1PolyimideUpilex SSilicone rubberx-34-2888PolyimideUpilex S400SiliconeSR236140AAExample 2PolyimideUpilex SSilicone rubberx-34-2888PolymethylpenteneDX8453200SiliconeSR236140ABExample 3PolyimideUpilex SSilicone rubberx-34-2888PolyimideUpilex S400PolymethylpenteneMX00427BAExample 4PolyimideUpilex SSilicone rubberx-34-2888PolyethyleneUHMW-PE400SiliconeSR236140ABComparative example 1PolyimideUpilex SSilicone rubberx-34-2888Polyvinyl chlorideTK-2500PE3800SiliconeSR236140ACComparative example 2PolyimideUpilex SSilicone rubberx-34-2888---PolymethylpenteneMX00230BC

[0079] As illustrated in Table 1, the fixing belts 1 to 4 of Examples 1 to 4 having an oxygen permeability of 3500 mL / (m 2< ·24hrs·atm) or less were satisfactory in separability and suppression of UFP generation.

[0080] In particular, in the fixing belts 1 and 3 of Examples 1 and 3 in which the oxygen permeability was less than or equal to 2000 mL / (m 2< ·24hrs·atm), the suppression of the occurrence of UFPs was particularly satisfactory. The fixing belt 4 of Example 4, which had anoxygen permeability of 2000 mL / (m 2< ·24hrs·atm) or less and was made of polyethylene, was satisfactory at suppressing the occurrence of UFP.

[0081] Furthermore, in the fixing belts 1, 2, and 4 of Examples 1, 2, and 4 in which the material of the surface layer was silicone, the separability was particularly satisfactory.

[0082] In the fixing belt 4 of Example 4 in which the oxygen permeability was 400 mL / (m 2< ·24hrs·atm), the suppression of the generation of UFP was satisfactory. This is probably because the melting point of the intermediate layer is 150°C and thus the suppression of the occurrence of UFP was reduced as compared with the fixing belts 1 and 3 in Examples 1 and 3.

[0083] On the other hand, in the fixing belts 5 and 6 of Comparative Examples 1 and 2 in which the oxygen permeability exceeded 3500 mL / (m 2< ·24hrs·atm) or no intermediate layer was present, the suppression of the occurrence of UFP was unsatisfactory.Industrial Applicability

[0084] According to the present invention, a further increase in speed, improvement in performance, and energy saving in an electrophotographic image forming apparatus are expected, and a further spread of image forming apparatuses is expected.Reference Signs List

[0085] 10 Image forming apparatus 20 Image reading section 21 Sheet feed device 22 Scanner 23 CCD Sensor 24 Image processing section 30 Image forming section 31 Image forming unit 32 Photosensitive drum 33 Charging device 34 Exposure device 35 Developing device 36 Cleaning device 40 Intermediate transfer section 41 Primary transfer unit 42 Secondary transfer unit 43 Intermediate transfer belt 44 Primary transfer roller 45 Backup roller 46 First support roller 47 Cleaning device 48 Secondary transfer belt 49 Secondary transfer roller 50 Second support roller 60 Fixing device 61 Fixing member 61a Base layer 61b Elastic layer 61c Intermediate layer 61d Surface layer 62 Heating roller 63 First pressure roller 64 Second pressure roller 65, 66 Heater 67 First temperature sensor 68 Second temperature sensor 69 Airflow separation device 70 Guide plate 71 Guide roller 80 Recording medium conveyance section 81 Sheet feeding tray unit 82 Registration roller pair D Document S Sheet (recording medium)

Claims

1. A fixing member (61), comprising: a base layer (61a); an elastic layer (61b) laminated on the base layer (61a); an intermediate layer (61c) laminated on the elastic layer (61b), the intermediate layer (61c) including a first resin and not including a fluorine compound; and a surface layer (61d) laminated on the intermediate layer (61c), the surface layer (61d) including a second resin and not including a fluorine compound; wherein the intermediate layer (61c) has an oxygen permeability of 3500 mL / (m2·24hrs·atm) or less at 25°C.

2. The fixing member (61) according to claim 1, wherein the oxygen permeability of the intermediate layer (61c) is 2000 mL / (m2·24hrs·atm) or less at 25°C.

3. The fixing member (61) according to claim 1, wherein the surface layer (61d) has a hexadecane contact angle of more than 25° at 150°C.

4. The fixing member (61) according to claim 1, wherein: the first resin has a tensile strength of 20 MPa or more; and the first resin has a melting point of 200°C or higher.

5. The fixing member (61) according to claim 1, wherein: the fixing member (61) has an endless belt shape; the base layer (61a) is disposed on an inner side in the fixing member (61); and the surface layer (61d) is disposed on an outer side in the fixing member (61).

6. A fixing device (60), comprising: the fixing member (61) according to claim 5; a plurality of rollers (62, 63) that axially support the fixing member (61); and a heater (65) for heating the fixing member (61).

7. The fixing device (60) according to claim 6, wherein the heater (65) is a heat source disposed on a back side of the fixing member (61), a halogen heater disposed inside the roller (62), or an electromagnetic induction coil disposed inside the roller (62).

8. An image forming apparatus (10) comprising the fixing device (60) according to claim 6 or 7, wherein an unfixed toner image formed on a recording medium (S) by an electrophotographic method is fixed to the recording medium (S) by heating and pressurizing.

Images