Fixing member and heat fixing device

Abstract

To provide a fixing member capable of obtaining excellent image quality while having high thermal conductivity.SOLUTION: When a thickness of the surface layer is T, a region from a position of 0.2*T in a depth direction from an outer surface of the surface layer to a surface of the surface layer on a side opposite to the outer surface is a region A, and a region from the position of 0.2*T in the depth direction from the outer surface to the surface layer is a region B, an amount of the carbon black with respect to 100 parts by mass of the fluorine-based resin in the region A is 1.0 part by mass or less, and an amount of the carbon black with respect to 100 parts by mass of the fluorine-based resin in the region B is 4.0 parts by mass or more and 10.0 parts by mass or less, the surface layer contains spherulites of a fluorine-based resin, at least a part of an outer surface of the surface layer is composed of spherulites, a thermal conductivity λ in a thickness direction of the surface layer is 0.21 (W / m·K), and an arithmetic average roughness Ra of the outer surface of the surface layer is 0.2 μm or less.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a fixing member used in a heat fixing device of an electrophotographic image forming apparatus, and to the heat fixing device. [Background technology]

[0002] Fixing members used in the heat fixing devices of electrophotographic image forming devices such as printers, copiers, and facsimiles are available in film or roller shapes. Known fixing members include those that have a film or roller-shaped substrate made of heat-resistant resin or metal, optionally with an elastic layer made of heat-resistant rubber or the like formed on the substrate, and a surface layer containing a fluororesin that has excellent toner releasability. Here, the fluororesin contained in the surface layer is preferably a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), which has excellent heat resistance.

[0003] In recent years, there has been an increasing demand for resource conservation, and there is an increasing demand for fixing members with high heat transfer efficiency that can maintain fixability even with low power consumption. Furthermore, there is an increasing demand for higher image quality in the finished product, and it is also important to make the surface layer of the fixing member smooth.

[0004] It has been found that improving the crystallinity is effective in increasing heat transfer efficiency. For example, Patent Document 1 describes an invention relating to improving the crystallinity of the surface layer of a fixing member, but this invention still has room for improvement. Furthermore, Patent Document 2 proposes that a high level of surface smoothness can be achieved by using a fluororesin with small spherulite size as a release layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-93650 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-10430 [Patent Document 3] Japanese Patent Application Publication No. 2018-28637 Summary of the Invention [Problem to be solved by the invention]

[0006] As described in Patent Document 1, the crystallinity of the PFA can be increased by heating the fixing member above the melting point of the PFA used in the release layer and then slowly cooling it. However, when PFA is slowly cooled, the crystal growth rate increases relative to the frequency of spherulite nuclei, resulting in the formation of large spherulites on the release layer surface. This increases the irregularities along the spherulite shape, reducing the surface smoothness of the fixing member. This creates the problem of the irregularities on the release layer surface being transferred to the image surface, resulting in reduced image quality.

[0007] In addition, as in Patent Document 3, the method of adding a thermally conductive filler to the release layer is also a common method for improving the heat transfer efficiency (thermal conductivity) of a component, but the addition of the filler reduces surface smoothness, resulting in reduced image quality. An object of the present disclosure is to provide a fixing member that has high thermal conductivity and yet can provide good image quality. [Means for solving the problem]

[0008] In order to solve the above problems, the present disclosure provides: A fixing member having a base layer, an elastic layer on the base layer, and a surface layer on the elastic layer, the surface layer contains a fluorine-based resin as a binder and carbon black, where T is the thickness of the surface layer, Region A is the region from the outer surface of the surface layer in the depth direction to a position at a thickness of 0.2×T, and Region B is the region from the outer surface in the depth direction from the position at a thickness of 0.2×T to a face of the surface layer on the opposite side from the outer surface, the amount of carbon black per 100 parts by mass of the fluororesin in Region A is 1.0 part by mass or less, and the amount of carbon black per 100 parts by mass of the fluororesin in Region B is 4.0 parts by mass or more and 10.0 parts by mass or less, the surface layer contains spherulites of the fluororesin, At least a portion of the outer surface of the surface layer is made up of the spherulites, the thermal conductivity λ of the surface layer in the thickness direction is 0.21 (W / m K) or more; The fixing member is characterized in that the arithmetic mean roughness Ra of the outer surface of the surface layer is 0.20 μm or less. [Effects of the Invention]

[0009] By heating and melting a PFA tube with a CB (carbon black) rich inner surface and a CB poor outer surface, the crystallinity is improved and thermal conductivity is increased. The presence of the CB rich layer reduces the spherulite size and improves surface smoothness, resulting in glossy, uniform images despite energy savings. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view schematically illustrating an image forming apparatus. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating a fixing device. [Figure 3] FIG. 2 is a cross-sectional view schematically illustrating a fixing film. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, specific examples (examples) of embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the following examples. <One embodiment> One embodiment is for a fuser member. The fixing member of the present disclosure comprises: A fixing member having a base layer, an elastic layer on the base layer, and a surface layer on the elastic layer, the surface layer contains a fluorine-based resin as a binder and carbon black, where T is the thickness of the surface layer, Region A is the region from the outer surface of the surface layer in the depth direction to a position at a thickness of 0.2×T, and Region B is the region from the outer surface in the depth direction from the position at a thickness of 0.2×T to a face of the surface layer on the opposite side from the outer surface, the amount of carbon black per 100 parts by mass of the fluororesin in Region A is 1.0 part by mass or less, and the amount of carbon black per 100 parts by mass of the fluororesin in Region B is 4.0 parts by mass or more and 10.0 parts by mass or less, the surface layer contains spherulites of the fluororesin, At least a portion of the outer surface of the surface layer is made up of the spherulites, the thermal conductivity λ of the surface layer in the thickness direction is 0.21 (W / m K) or more; The surface layer is characterized in that the outer surface thereof has an arithmetic mean roughness Ra of 0.20 μm or less. Each item will be explained below.

[0012] 1 is a cross-sectional view of a color electrophotographic printer 1, which is an example of an image forming apparatus according to this embodiment, taken along the conveyance direction of a recording material P. In this embodiment, the color electrophotographic printer is simply referred to as a "printer."

[0013] The printer 1 shown in FIG. 1 includes image forming units 10 for the colors Y (yellow), M (magenta), C (cyan), and BK (black). A photosensitive drum 11 is pre-charged by a charger 12. A latent image is then formed on the photosensitive drum 11 by a laser scanner 13. The latent image is then converted into a toner image by a developing unit 14. The toner image on the photosensitive drum 11 is sequentially transferred by a primary transfer blade 17 to an image carrier, such as an intermediate transfer film 31. After transfer, any toner remaining on the photosensitive drum 11 is removed by a cleaner 15. As a result, the surface of the photosensitive drum 11 becomes clean and is ready for the next image formation.

[0014] Meanwhile, recording material P is fed one sheet at a time from paper feed cassette 20 or multi-paper feed tray 25 and sent to registration roller pair 23. Registration roller pair 23 temporarily receives recording material P and straightens it out if it is skewed. Then, registration roller pair 23 synchronizes with the toner image on intermediate transfer film 31 and sends recording material P between intermediate transfer film 31 and secondary transfer roller 35. The color toner image on the intermediate transfer film is transferred to recording material P by a transfer body, such as secondary transfer roller 35. Thereafter, the toner image on recording material P is fixed to recording material P by heating and pressing recording material P by fixation unit 40.

[0015] Next, the fixing device used in this example will be described. A film-heating type heating device (tensionless type) was used, as shown in the schematic configuration diagram of fixing unit 40 in Figure 2. The heat fixing device of the present disclosure is a heat fixing device in an electrophotographic image forming apparatus, and includes a heating body, a fixing member that slides and rotates on the surface of the heating body, and a pressure member that heats and presses a recording material via the fixing member, and the fixing member is the fixing member of the present disclosure.

[0016] The heater 43 is a ceramic heater (hereinafter also referred to as a heater) as a heating element of the present disclosure. This heater 43 is basically composed of a long, thin ceramic substrate with its longitudinal direction perpendicular to the drawing and an energized heat-generating resistor layer provided on the surface of this substrate. It is a low-heat capacity heater that heats up with a steep rise in temperature overall when current is applied to the heat-generating resistor layer. In addition, it is configured to switch the energized area depending on the longitudinal width size of the recording material.

[0017] The fixing film 41 is a cylindrical (endless) heat-resistant fixing film (fixing member of the present disclosure) that serves as a heating member for transmitting heat, and is loosely fitted around a support member including the heater 43. The fixing film 41 in this embodiment is as shown in Fig. 3, and is a fixing film having a three-layer composite structure of at least a surface layer 41a, an elastic layer 41c, and a base layer 41d.

[0018] The pressure roller 44 is a heat-resistant elastic pressure roller serving as a pressure member of the present disclosure, and is made of a core metal and an elastic layer made of heat-resistant rubber such as silicone rubber or fluororubber, or a silicone rubber foam, with both ends of the core metal rotatably supported by bearings. The fixing film 41 and heater 43 are arranged above the pressure roller 44, parallel to the pressure roller 44 with respect to the heater 43 side, and are pressed by a pressing member (not shown) to bring the lower surface of the heater 43 and the upper surface of the pressure roller 44, via the fixing film 41, into pressure contact against the elasticity of the roller elastic layer, thereby forming a fixing nip portion of a predetermined width as a heating portion.

[0019] The pressure roller 44 is driven to rotate counterclockwise as indicated by the arrow at a predetermined peripheral speed by a driving means (not shown). The rotation of the pressure roller 44 generates a frictional force between the pressure roller 44 and the fixing film 41 at the fixing nip, which acts on the cylindrical fixing film 41, causing the fixing film 41 to rotate clockwise as indicated by the arrow while sliding in close contact with the downward surface of the heater 43. The support member also serves as a rotation guide member for the cylindrical fixing film 41.

[0020] The pressure roller 44 is driven to rotate, and the cylindrical fixing film 41 is driven to rotate accordingly. Also, power is applied to the heater 43, causing the heater to heat up quickly and reach a predetermined temperature, and in this state the recording material P carrying an unfixed toner image T is introduced between the fixing film 41 and the pressure roller 44 in the fixing nip portion, and the toner image-carrying side of the recording material P comes into close contact with the outer surface of the fixing film 41 in the fixing nip portion, and the recording material P is sandwiched and transported through the fixing nip portion together with the fixing film 41.

[0021] During this nipping and conveying process, the recording material P is heated by the heat of the fixing film 41 heated by the heater 43, and the unfixed toner image T on the recording material P is melted and fixed by heat and pressure onto the recording material P. After passing through the fixing nip portion, the recording material P is separated from the surface of the fixing film 41 by curvature and is conveyed to be discharged.

[0022] A contact thermometer (thermistor) 45 measures the temperature of the fixing film 41 heated by the heater 43, and transmits the detection result to a temperature control means (not shown). The heater holder 46 is a member that holds the heater 43 when it has been heated to a high temperature.

[0023] Next, the fixing film will be described in detail. The fixing film (fixing member) of the present disclosure is a fixing film comprising a base layer having an endless shape, an elastic layer provided on the outer peripheral surface of the base layer, and a surface layer on the outer peripheral surface of the elastic layer.

[0024] The fixing film 41 in the present disclosure is as shown in Fig. 3. The fixing film has a base layer 41d, an elastic layer 41c that covers the outer surface of the base layer 41d, and a surface layer 41a that covers the surface of the elastic layer 41c opposite to the side facing the base layer 41d. Note that the surface layer 41a has an adhesive layer 41b made of resin on the surface of the elastic layer 41c opposite to the side facing the base layer 41d.

[0025] (1) Base layer The fixing member of the present disclosure has a base layer 41d. The material of the base layer 41d is not particularly limited, and any known material used as a base layer for fixing members such as fixing films can be used. In the fixing member of the present disclosure, the base layer 41d preferably includes a metal or alloy containing at least one selected from the group consisting of aluminum, iron, stainless steel, and nickel, and / or a polyimide resin. The thickness is not particularly limited, but is preferably 20 μm or more and 100 μm or less from the viewpoints of strength, flexibility, and heat capacity. In the present invention, the chemical species of the base layer 41d, elastic layer 41c, adhesive layer 41b, surface layer 41a, etc. can be confirmed by nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), or the like.

[0026] The outer surface of the base layer 41d may be subjected to a surface treatment to provide adhesion to the elastic layer 41c. The surface treatment may be one or a combination of physical treatments such as blasting, lapping, or polishing, or chemical treatments such as oxidation, coupling agent treatment, or primer treatment.

[0027] When the elastic layer 41c containing silicone rubber is provided on the surface of the base layer 41d, it is preferable to apply a primer treatment to the surface of the base layer 41d in order to improve the adhesion between the base layer 41d and the elastic layer 41c. Examples of the primer used for the primer treatment include paint in which a silane coupling agent, a silicone polymer, a hydrogenated methylsiloxane, an alkoxysilane, a reaction-accelerating catalyst, and a colorant such as red iron oxide are appropriately mixed and dispersed in an organic solvent.

[0028] The primer can be appropriately selected depending on the material of the base layer 41d, the type of the elastic layer 41c, or the form of crosslinking reaction. In particular, when the elastic layer contains a large amount of unsaturated aliphatic groups, a primer containing a hydrosilyl group is preferably used to impart adhesiveness by reacting with the unsaturated aliphatic groups. When the elastic layer contains a large amount of hydrosilyl groups, a primer containing an unsaturated aliphatic group is preferably used.

[0029] Other examples of primers include those containing alkoxy groups. Commercially available primers can be used. The primer treatment includes applying the primer to the outer surface of the base layer (the surface to be bonded to the elastic layer) and drying or baking it.

[0030] (2) Elastic layer The fixing member of the present disclosure has an elastic layer 41c on a base layer 41d. The material of the elastic layer 41c is not particularly limited, and any known material used as an elastic layer for fixing members such as fixing films can be used. In the fixing member of the present disclosure, the elastic layer 41c preferably contains silicone rubber, which has excellent heat resistance. Furthermore, addition-curing liquid silicone rubber is preferably used as the raw material for the silicone rubber.

[0031] The thickness of the elastic layer 41c can be appropriately designed in consideration of the surface hardness of the fixing film and the width of the fixing nip portion to be formed. When the fixing film is the fixing film 41, the thickness of the elastic layer 41c is preferably 100 μm or more and 1000 μm or less.

[0032] By setting the thickness of the elastic layer 41c within this range, it is possible to ensure a sufficient width of the fixing nip portion when the fixing film is incorporated into a fixing device. The elastic layer 41c may contain a filler, which is added to control the thermal conductivity, heat resistance, and elastic modulus.

[0033] Specifically, these include non-conductive fillers such as silicon carbide (SiC), silicon nitride (Si3N4), silica (SiO2), boron nitride (BN), aluminum nitride (AlN), alumina (Al2O3), iron oxide (Fe2O3), zinc oxide (ZnO), magnesium oxide (MgO), and titanium oxide (TiO2).

[0034] The material constituting elastic layer 41c may contain a reaction control agent (inhibitor) to control the reaction start time. Known reaction control agents such as methylvinyltetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohol, and hydroperoxide are used.

[0035] (3) Adhesive layer The fixing member of the present disclosure preferably has an adhesive layer 41b. An addition-curing silicone rubber adhesive is used for the adhesive layer 41b. This adhesive contains uncrosslinked silicone rubber components, and when heated, bonds with the uncrosslinked components of the inner surface treatment layer of the surface layer 41a and the elastic layer 41c, thereby bonding the surface layer 41a and the elastic layer 41c.

[0036] (4) Surface layer The fixing member of the present disclosure has a surface layer 41a, which contains a fluororesin as a binder and carbon black. The fluororesin is not particularly limited, and known fluororesins can be used. The fluororesin of the present disclosure preferably contains tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). Examples of fluororesins include fluorinated ethylene propylene (FEP), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene hexafluoropropylene vinylidene fluoride (THV), and tetrafluoroethylene-ethylene copolymer (ETFE). One type of fluororesin may be used alone, or two or more types may be used in combination. In the present disclosure, the fluororesin contains at least carbon black. Furthermore, the fluororesin may contain a conductive material or a filler.

[0037] The tube for an image-forming apparatus according to the present disclosure may have a single-layer structure including only a layer formed of a fluororesin, as shown in FIG. 3, or may have a multi-layer structure including layers formed of a fluororesin, as shown in FIG.

[0038] In the fixing member of the present disclosure, the thickness of the surface layer 41a is T, the region from the outer surface of the surface layer 41a in the depth direction to a position at a thickness of 0.2 × T is defined as region A, and the region from the outer surface in the depth direction to a position at a thickness of 0.2 × T is defined as region B. In region A, the amount of carbon black per 100 parts by mass of the fluororesin is 1.0 part by mass or less, and in region B, the amount of carbon black per 100 parts by mass of the fluororesin is 4.0 parts by mass or more and 10.0 parts by mass or less. In this case, T is preferably 10 μm or more and 40 μm or less. This provides the surface layer 41a with releasability, favorable thermal conductivity (described below), and the strength required for a surface layer. The value of T can be confirmed by a cross-sectional scanning electron microscope (SEM) image.

[0039] Furthermore, when the total thickness of the PFA-containing layer is T, if the amount of carbon black per 100 parts by mass of fluororesin in region A extending from the outer surface of the PFA-containing layer to a depth of 0.2 × T exceeds 1.0 part by mass, the releasability required for use as surface layer 41a during fixing will be impaired.

[0040] Furthermore, if the amount of carbon black per 100 parts by mass of fluororesin in region B is less than 4.0 parts by mass, the required thermal conductivity will not be achieved, and if it exceeds 10.0 parts by mass, there are concerns that the strength of the component will be significantly reduced, leading to manufacturing issues.

[0041] Furthermore, in the fixing member of the present disclosure, the surface layer 41a contains spherulites of the fluororesin, and at least a portion of the outer surface of the surface layer 41a is made up of the spherulites. The surface layer containing spherulites has a higher degree of crystallinity than the surface layer containing no spherulites. A high degree of crystallinity is excellent in terms of thermal conductivity and abrasion resistance, and the fixing member of the present disclosure preferably has a degree of crystallinity of surface layer 41a of 26% or more and 30% or less.

[0042] In the fixing member of the present disclosure, the arithmetic mean roughness Ra of the surface of the surface layer 41a is 0.2 μm or less, and preferably 0.07 μm or more. By having an Ra of 0.2 μm or less, the surface smoothness is improved, and a fixed image with high image gloss can be obtained. By reducing the diameter of the spherulites present in the surface layer through the nucleation effect of carbon black, Ra can be reduced to 0.2 μm or less, resulting in high surface smoothness and high image gloss.

[0043] In the fixing member of the present disclosure, the thermal conductivity λ of the surface layer 41a in the thickness direction is 0.21 (W / m·K) or more, and preferably λ is 0.24 (W / m·K) or more and 0.26 (W / m·K) or less. This reduces uneven toner melting and provides good image quality.

[0044] <Evaluation of melting unevenness> By observing the melted state of the toner after fixing the toner image formed on the paper, it is possible to obtain an index of the ability of the fixing member to follow the unevenness of the paper.

[0045] Using the same film-heating fixing device 40 as used in the evaluation of abrasion resistance, images for evaluating melting unevenness are fixed on 10 sheets in succession under an environment of a temperature of 10°C and a relative humidity of 50%. The paper used is A4-sized recycled paper (product name: Recycled Paper GF-R100; manufactured by Canon Inc., thickness 92 μm, basis weight 66 g / m). 2 The paper used was 70% recycled paper, with a Beck smoothness of 23 seconds (measured using a method conforming to JIS P8119). The image used to evaluate uneven melting was a 10 μm x 10 μm patch image formed with cyan toner and magenta toner at 100% concentration, placed near the center of the paper.

[0046] As a guideline for uneven melting, sufficient heat and pressure must be applied to the image area where two colors are formed, causing the toner to melt and mix. In particular, if heat is applied but no pressure is applied to the concave areas of the paper, the toner grain boundaries remain after fixing, resulting in insufficient color mixing and uneven melting. If the fixing member cannot adequately conform to the concave and convex surfaces, pressure is applied to the convex areas, causing color mixing, but insufficient color mixing in the concave areas. Therefore, conformability to the concave and convex surfaces was confirmed by observing the melting state of the image-forming area.

[0047] After printing 10 consecutive sheets of images for evaluating uneven melting, a sample of the 10th sheet was taken out and the image-formed area was observed under an optical microscope to evaluate uneven melting. The evaluation criteria were as follows. If the evaluation was A to C according to the following evaluation criteria, it was determined that the effects of the present disclosure were achieved. (Evaluation criteria) A: The toner grain boundaries are not visible even in the recesses of the paper fibers, and the colors are mixed in both the recesses and protrusions. B: Toner grain boundaries are barely visible even in the recesses of the paper fibers, and the colors are mixed in both the recesses and protrusions. C: Although some toner grain boundaries are observed in the recesses of the paper fibers, the colors are generally mixed in both the recesses and protrusions. D: Only the convex parts of the paper fibers are mixed, and many toner grain boundaries are observed in the concave parts.

[0048] <Evaluation of image gloss> The evaluation of image glossiness was carried out using the same film-heating type fixing device 40 as in the evaluation of abrasion resistance. A black solid image was fixed in an environment of 23°C and 50% relative humidity, with the surface temperature of the fixing film at the paper passing portion adjusted to 160°C. The paper used was A4 size paper (product name: GFC-081 (81.0 G / m 2 ); sold by Canon Marketing Japan Inc.) was used. The 60° gloss (glossiness at an incident angle of 60°) of the output image was measured using a gloss meter (handheld gloss meter PG-1M manufactured by Nippon Denshoku Industries Co., Ltd.), and the average value was evaluated according to the following criteria. If the evaluation was A to C according to the following evaluation criteria, it was determined that the effects of the present disclosure had been obtained. (Evaluation criteria) A: 60° gloss is 10 or more B: 60° gloss is 8 or more and less than 10 C: 60° gloss is 6 or more and less than 8 D: 60° gloss is less than 6 [Example]

[0049] (Method of manufacturing fixing film) Next, a method for producing the fixing film (fixing member) used in this example will be described. In this example, the fixing film was produced by a manufacturing method consisting of steps 1 to 4.

[0050] Surface layer 41a is made of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). PFA is a copolymer of perfluoroalkyl vinyl ether (PAVE) and tetrafluoroethylene (TFE). Surface layer 41a made of PFA is formed by applying a dispersion liquid (water-based dispersion paint) or powder paint containing PFA as a main component to the surface of elastic layer 41c, and then heating the coating to above its melting point to form a film. Alternatively, a PFA tube manufactured by extrusion molding is used to cover the surface of elastic layer 41c. As the PFA, commercially available products can be used.

[0051] Specific examples include AP-230 (trade name, manufactured by Daikin Industries, Ltd.) and AP-231SH (trade name, manufactured by Daikin Industries, Ltd.), which is a PFA with fully fluorinated terminal groups. Furthermore, when the thermal conductivity of the PFA-containing layer in the thickness direction is λ≧0.21 (W / m·K), uneven toner melting can be suppressed.

[0052] One method for achieving a thermal conductivity λ of 0.21 (W / m·K) in the thickness direction of the PFA-containing layer is to heat the surface layer 41a formed during the manufacturing process of the fixing member to a temperature equal to or higher than the melting point of PFA, and then control the cooling rate to promote crystallization of the PFA. Although the specific method is not particularly limited, the following methods for heat treatment of the surface layer can be used.

[0053] To heat the entire fixing member, an upright cylindrical heating cylinder capable of heating up to 330°C or higher is used. A band heater equipped with a thermocouple is installed inside the heating cylinder to control the heating temperature of the fixing member. The heating temperature is preferably between the melting point of PFA and 350°C. The heating time may be any time long enough to allow the temperature of the surface layer 41a to reach the desired temperature, and may be, for example, 1 to 20 minutes, 1 to 10 minutes, or 2 to 5 minutes.

[0054] After heating is complete, the cooling rate of the heating barrel is controlled to control the cooling rate of the fixing member. For example, the cooling rate can be controlled by providing an air supply nozzle on the outer periphery of the heating barrel and adjusting the air flow rate. The slower the cooling rate in the PFA crystallization temperature range, the more the crystallization of PFA can be promoted. For the reasons mentioned above, it is preferable to adjust the cooling rate so that the crystallinity is 26% or higher.

[0055] The PFA tube can be produced, for example, by extruding molten PFA through a cylindrical die. Such a PFA tube is rapidly cooled during the extrusion process, causing rapid crystallization, resulting in crystals oriented in the extrusion direction and a low degree of crystallinity. After the PFA tube is coated on the surface of the elastic layer 41c to form the surface layer 41a, the surface layer is subjected to the aforementioned heat treatment, thereby increasing the degree of crystallinity and forming spherulites on the outer surface of the surface layer 41a.

[0056] The methods for measuring each physical property in the present disclosure are shown below. <Method for measuring thermal conductivity> First, the surface layer was isolated from the fixing member. The thermal diffusivity of the isolated surface layer was measured at 25°C using a cyclic heating method (temperature wave thermal analysis method) thermal diffusivity measuring device (product name: FTC-1, manufactured by Advance Riko Co., Ltd.). The thermal conductivity was calculated by multiplying the obtained thermal diffusivity by the separately measured density and specific heat.

[0057] <How to check for spherulites> First, the surface layer is isolated from the fixing member. The isolated surface layer is then attached to a high-hardness plate such as a SUS plate, and the surface is thinly cut out using a surface and interface characterization analyzer (SAICAS) or similar. It is preferable to cut out a portion 0.2T from the surface. The surface thus obtained is observed under a microscope to obtain an image of the spherulites. It is preferable to obtain an image that can confirm the structure of the spherulites using a transmission polarizing microscope, but it is also possible to use a known microscope such as an optical microscope or scanning electron microscope that can confirm the shape of the spherulites on the outer surface of the surface layer. The spherulites are confirmed from the obtained image.

[0058] <Method for measuring crystallinity> First, the surface layer is isolated from the fixing member. Specifically, the surface layer is peeled off from the substrate together with the elastic layer, and the elastic layer adhered to the surface layer is dissolved in a solvent, thereby isolating only the surface layer.

[0059] The endothermic peak temperature and endothermic amount are measured using a differential scanning calorimeter (product name: Q2000, manufactured by TA INSTRUMENTS). The melting points of indium and zinc are used to correct the temperature of the detector, and the heat of fusion of indium is used to correct the amount of heat.

[0060] Specifically, approximately 4 mg of the surface layer is weighed and placed in an aluminum pan. An empty aluminum pan is used as a reference, and measurements are performed at a heating rate of 20°C / min within a measurement range of 25°C to 400°C. The sample is heated to 400°C once and held there for 5 minutes, then cooled to 25°C at a rate of 20°C / min, after which the sample is heated again. During the first heating process, the area enclosed by the temperature-endothermic curve including the endothermic peak and the baseline is taken as the endothermic amount. The degree of crystallinity of PFA can be calculated by dividing the endothermic amount by the heat of fusion of PTFE (92.9 J / G) for complete crystallization.

[0061] <Method for measuring the arithmetic mean roughness Ra of the release layer surface> The arithmetic mean roughness Ra of the release layer surface is measured using a contact type roughness meter (product name: SE-3500, manufactured by Kosaka Manufacturing Co., Ltd.) The various conditions for the measurement are as follows. Standard: JIS B0601 / ISO 4287 1997 (Roughness) Cutoff wavelength: 0.8 mm Evaluation length: 4.0 mm Scanning speed: 1.0 mm / s Measurement magnification: 5000x The average value is calculated by measuring 12 randomly selected points on the surface layer.

[0062] <Method for measuring the amount of carbon black contained in the surface layer> The amount of carbon black contained in the surface layer is measured using a TGA / SDTA851e (manufactured by METTLER TOLEDO). First, the surface layer is isolated from the fixing member. Specifically, the surface layer is peeled off from the substrate together with the elastic layer, and the elastic layer adhered to the surface layer is dissolved in a solvent, thereby isolating only the surface layer. Approximately 20 mg of the surface layer is precisely weighed and placed in an aluminum pan, and the weight change is measured using the following procedure. (1) Isothermal: 40℃_5min, N2_50ml / min (2) Temperature increase: 20K / min (40℃→600℃), N2 50ml / min (3) Isothermal: 600℃_10min, N2_50ml / min (4) Temperature drop: -20K / min (600℃→400℃), N2_50ml / min (5) Temperature increase: 20K / min (400℃→600℃), Air_50ml / min (6) Isothermal: 600℃_150min, Air_50ml / min

[0063] The mass ratio of carbon black in the surface layer is calculated by (ratio of mass at the end of (3) to initial mass) - (ratio of mass at the end of (6) to initial mass). The mass ratio of carbon black in the surface layer is calculated by (mass ratio of carbon black in the surface layer) / (1 - (mass ratio of carbon black in the surface layer)) x 100, which is the amount (parts by mass) of carbon black per 100 parts by mass of PFA resin.

[0064] Example 1 (Inner surface treatment of PFA tube) Fluorine-based resin (area A: PFA resin not blended with carbon black, etc.) and (area B: PFA resin blended with carbon black (10.0 parts by mass of carbon black per 100 parts by mass of PFA resin)) were melt-extruded using a circular die to prepare a single-layer cylindrical tube (fluororesin tube) for image-forming devices with a thickness of 30 μm.

[0065] The PFA resin in region A was 950HP-Plus (manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd.), and the PFA resin in region B was C-9068 (manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd.) These PFA resin pellets were each supplied to an extruder equipped with a two-layer circular die and melt-extruded, and the extruded product was cooled at room temperature while being produced substantially without stretching.

[0066] An aqueous solution containing 5% by weight of sodium benzoate and 1% by weight of Surflon S-113 (AGC Seimi Chemical Co., Ltd.) was applied to the entire inner surface of the PFA tube, and after air drying, it was subjected to 300 mJ / cm 2 The tube was irradiated with six shots of KRF excimer laser light at 1 / 1000 pulses to obtain a PFA tube with an inner surface treated.

[0067] (base material) A stainless steel (SUS) substrate with an inner diameter of 24 mm and a thickness of 30 μm was used.

[0068] (Formation of inner sliding layer) First, a polyimide precursor solution was obtained by reacting approximately equimolar amounts of an aromatic tetracarboxylic dianhydride or its derivative with an aromatic diamine in an aprotic polar organic solvent. The obtained polyimide precursor solution was applied to the inner surface of the substrate by ring coating, and after drying the solvent in an electric furnace, the substrate was heated at 260 to 400°C for approximately 1 hour to form an inner sliding layer. The thickness of the inner sliding layer was 12 μm.

[0069] (Formation of primer layer and elastic layer) A primer layer and an elastic layer were formed on the substrate on which the inner sliding layer had been formed by the following procedure. A hydrosilyl silicone primer (DY39-051 A / B; Dow-Toray) was applied to the substrate and cured at 200°C for 5 minutes. An addition reaction liquid silicone rubber using alumina as a filler was applied to the primer layer and cured at 200°C for 30 minutes, forming a 250 μm-thick elastic silicone rubber layer.

[0070] (Applying adhesive layer) After forming the elastic layer, an adhesive (SE1819CV A / B; manufactured by Dow-Toray Industries, Inc.) was applied to a thickness of 7 μm on the elastic layer using a ring coating method.

[0071] (Formation of surface layer) After applying the adhesive, a PFA tube with an internally treated surface was vacuum-expanded from the outside to form a surface layer (vacuum expansion coating). Specifically, the PFA tube was vacuum-adsorbed onto the inner surface of an outer cylinder with an inner diameter larger than the outer diameter of the workpiece after the adhesive-coated elastic layer was formed, expanding the diameter. The workpiece was then inserted into the tube, and the vacuum was released to coat the PFA tube on the adhesive. After removing excess adhesive and air between the PFA tube and the elastic layer using an O-ring or similar, the adhesive was cured and bonded using heating means such as an electric furnace. Both ends were then cut to the desired length.

[0072] (Heat treatment of the surface layer) After cutting both ends to the desired length, the specimen was inserted into a heating cylinder with an inner diameter of 42 mm and heated over its entire area using a band heater inside the heating cylinder. The heating temperature was controlled to 330°C, and the actual temperature of the surface layer was controlled to be above the melting temperature of PFA.

[0073] The heating time was set to 3 minutes after the fixing film was placed in the heating barrel, which was the time required for the surface layer to reach the desired temperature. After 3 minutes had passed, the heating barrel was cooled to 200°C at a rate of 20°C / min, and then the fixing film was taken out of the heating barrel into a room temperature atmosphere to obtain a fixing film. The measurement results of the prepared fixing film are shown in Table 1.

[0074] <Example 2> A fixing film was obtained in the same manner as in Example 1, except that in the heat treatment of the surface layer, the cooling rate of the heating barrel was changed to 60° C. / min.

[0075] Example 3 A fixing film was obtained in the same manner as in Example 1, except that the amount of carbon black per 100 parts by mass of PFA resin in region B was changed to 4.0 parts by mass in the material of the surface layer.

[0076] Example 4 A fixing film was obtained in the same manner as in Example 3, except that in the heat treatment of the surface layer, the cooling rate of the heating barrel was changed to 60° C. / min.

[0077] <Example 5> A fixing film was obtained in the same manner as in Example 1, except that the thickness of the surface layer was changed to 10 μm.

[0078] Example 6 A fixing film was obtained in the same manner as in Example 5, except that in the heat treatment of the surface layer, the cooling rate of the heating barrel was changed to 10° C. / min.

[0079] Example 7 A fixing film was obtained in the same manner as in Example 6, except that the amount of carbon black per 100 parts by mass of PFA resin in region B was changed to 4.0 parts by mass in the material of the surface layer.

[0080] Example 8 A fixing film was obtained in the same manner as in Example 3, except that the amount of carbon black in region A was changed to 1.0 part by mass relative to 100 parts by mass of the PFA resin in the surface layer material.

[0081] Example 9 A fixing film was obtained in the same manner as in Example 1, except that the amount of carbon black in region A was changed to 1.0 part by mass relative to 100 parts by mass of the PFA resin in the surface layer material.

[0082] Example 10 A fixing film was obtained in the same manner as in Example 1, except that the amount of carbon black in the surface layer was changed to 0.1 parts by mass relative to 100 parts by mass of the PFA resin in region A.

[0083] Example 11 A fixing film was obtained in the same manner as in Example 3, except that the amount of carbon black in region A was changed to 0.1 parts by mass relative to 100 parts by mass of the PFA resin in the surface layer material.

[0084] Example 12 A fixing film was obtained in the same manner as in Example 1, except that the amount of carbon black per 100 parts by mass of PFA resin in region B was changed to 8.0 parts by mass in the material of the surface layer.

[0085] <Comparative Example 1> A fixing film was obtained in the same manner as in Example 1, except that the amount of carbon black in region A was changed to 2.0 parts by mass relative to 100 parts by mass of the PFA resin in the surface layer material.

[0086] <Comparative Example 2> A fixing film was obtained in the same manner as in Example 1, except that the surface layer was not subjected to the heat treatment.

[0087] <Comparative Example 3> A fixing film was obtained in the same manner as in Example 1, except that the thickness of the surface layer was changed to 100 μm.

[0088] <Comparative Example 4> A fixing film was obtained in the same manner as in Example 1, except that the amount of carbon black per 100 parts by mass of PFA resin in region B was changed to 3.0 parts by mass in the material of the surface layer.

[0089] <Comparative Example 5> A fixing film was obtained in the same manner as in Example 1, except that in the heat treatment of the surface layer, the cooling rate of the heating barrel was changed to 200° C. / min. The results of Examples 1 to 12 and Comparative Examples 1 to 5 are summarized in Table 1.

[0090] [Table 1] As shown in this example, both surface smoothness and high thermal conductivity were achieved.

[0091] The disclosure of this embodiment includes the following configuration. (Configuration 1) A fixing member having a base layer, an elastic layer on the base layer, and a surface layer on the elastic layer, the surface layer contains a fluorine-based resin as a binder and carbon black, where T is the thickness of the surface layer, Region A is the region from the outer surface of the surface layer in the depth direction to a position at a thickness of 0.2×T, and Region B is the region from the outer surface in the depth direction from the position at a thickness of 0.2×T to a face of the surface layer on the opposite side from the outer surface, the amount of carbon black per 100 parts by mass of the fluororesin in Region A is 1.0 part by mass or less, and the amount of carbon black per 100 parts by mass of the fluororesin in Region B is 4.0 parts by mass or more and 10.0 parts by mass or less, the surface layer contains spherulites of the fluororesin, At least a portion of the outer surface of the surface layer is made up of the spherulites, the thermal conductivity λ of the surface layer in the thickness direction is 0.21 (W / m K) or more; The fixing member is characterized in that the arithmetic mean roughness Ra of the outer surface of the surface layer is 0.20 μm or less. (Configuration 2) 2. The fixing member according to claim 1, wherein the crystallinity of the surface layer is 26% or more. (Configuration 3) 2. The fixing member according to claim 1, wherein T is 10 μm or more and 40 μm or less. (Configuration 4) 2. The fixing member according to claim 1, wherein the fluorine-based resin contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). (Configuration 5) 2. The fuser member of claim 1, wherein the elastic layer comprises silicone rubber. (Configuration 6) 2. The fixing member according to claim 1, wherein the base layer comprises a metal or alloy including one or more selected from the group consisting of aluminum, iron, stainless steel, and nickel, and / or a polyimide resin. (Configuration 7) A heat fixing device in an electrophotographic image forming apparatus, The heat fixing device includes a heating body, a fixing member that rotates and slides on the surface of the heating body, and a pressure member that applies heat and pressure to a recording material via the fixing member, A heat fixing device, wherein the fixing member is the fixing member according to any one of the first to sixth aspects. [Explanation of symbols]

[0092] 10: Image forming unit 11: Photosensitive drum 12: Charger 13: Laser scanner 14: Developer 15: Cleaner 17: Primary transfer blade 20: Paper cassette 25: Multi-feed tray 23: Registration roller pair 31: Intermediate transfer film 35: Secondary transfer roller 40: Fixing unit 41: Fixing film 41a: Surface layer 41d: Base layer 41c: Elastic layer 41b: Adhesive layer 43: Heating body 44: Pressure roller 45: Contact thermistor 46: Heater holder 501: Corona discharge grid 502: Fixing member 503: Surface potential meter probe P: Recording material T: Toner

Claims

1. A fixing member having a base layer, an elastic layer on the base layer, and a surface layer on the elastic layer, the surface layer contains a fluorine-based resin as a binder and carbon black, where T is the thickness of the surface layer, Region A is a region from the outer surface of the surface layer in the depth direction to a position at a thickness of 0.2×T, and Region B is a region from the outer surface in the depth direction from the position at a thickness of 0.2×T to a face of the surface layer on the opposite side from the outer surface, the amount of carbon black per 100 parts by mass of the fluororesin in Region A is 1.0 part by mass or less, and the amount of carbon black per 100 parts by mass of the fluororesin in Region B is 4.0 parts by mass or more and 10.0 parts by mass or less, the surface layer contains spherulites of the fluororesin, At least a portion of the outer surface of the surface layer is made up of the spherulites, The thermal conductivity λ of the surface layer in the thickness direction is 0.21 (W / m K) or more, The fixing member is characterized in that the arithmetic mean roughness Ra of the outer surface of the surface layer is 0.20 μm or less.

2. 2. The fuser member of claim 1, wherein the surface layer has a crystallinity of 26% or more.

3. 2. The fixing member according to claim 1, wherein T is 10 [mu]m or more and 40 [mu]m or less.

4. 2. The fixing member according to claim 1, wherein the fluorine-based resin includes a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA).

5. The fuser member of claim 1 , wherein the elastic layer comprises a silicone rubber.

6. The fixing member according to claim 1 , wherein the base layer comprises a metal or alloy including one or more selected from the group consisting of aluminum, iron, stainless steel, and nickel, and / or a polyimide resin.

7. A heat fixing device in an electrophotographic image forming apparatus, The heat fixing device includes a heating body, a fixing member that rotates and slides on the surface of the heating body, and a pressure member that applies heat and pressure to a recording material via the fixing member, A heat fixing device, wherein the fixing member is the fixing member according to any one of claims 1 to 6.

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