Fixing member and heat fixing device

Abstract

To provide a fixing member capable of obtaining high image glossiness and excellent image quality while improving wear resistance with paper.SOLUTION: The surface layer contains crystals of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), a surface SA of the central area A and a surface SB of the end area B constituting the outer surface of the fixing member are each roughened by the crystals, and when the arithmetic average roughness of the surface SA is defined as RaA and the arithmetic average roughness of the surface SB is defined as RaB, the following formula (1) is satisfied: RaA> RaB (1) in a heat absorption curve obtained by measuring a sample sampled from the outermost layer in the end area B at a temperature increase rate of 20 °C. / min using a differential scanning calorimetry (DSC), an amount of heat absorption during the temperature increase is 21J / g or more.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Electrophotographic members, such as fixing members used in 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, for example, a film- or roller-shaped substrate made of heat-resistant resin or metal, on which an elastic layer or surface layer made of heat-resistant rubber or the like is formed as needed. For example, a fluororesin having releasability is used for the surface layer. A tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) is preferably used for the surface layer, as it is a fluororesin having excellent releasability for toner.

[0003] There is a demand for additional performance improvements, such as faster printing speeds, higher image quality, energy-saving performance, and compatibility with a wide variety of media. In particular, the surface layer of the fixing member is prone to wear from the edges of paper and scratches from foreign matter, which has a significant impact on the lifespan of the fixing member.

[0004] Patent Document 1 proposes a film-heating type image heating device with excellent power-saving properties as an image heating device to be installed in an image forming apparatus. In a film-heating type image heating device, a pressure roller, together with a heater, forms a fixing nip between the fixing film and the pressure roller for sandwiching and transporting a recording material, and an unfixed toner image is fixed to the recording material by heat from the heater while applying pressure at this fixing nip. The film is configured in a cylindrical shape, and inside it, a heater, a film guide, an inner sliding portion of a flange member, and the like are arranged, guiding the rotation of the fixing film, which is driven by the rotation of the pressure roller. Furthermore, Patent Document 2 proposes a fixing member in which the surface roughness of the central portion in the longitudinal direction is greater than that of the end portions in the longitudinal direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 4-44075 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-142832 Summary of the Invention [Problem to be solved by the invention]

[0006] In an image heating device such as that described in Patent Document 1, if the friction between the fixing member and the pressure member is small, slippage (microslip) of the fixing film against the pressure roller or recording material may occur, so there is room for improvement in the wear resistance of the surface of the fixing member caused by the edges of the recording material.

[0007] Furthermore, in a high-temperature, high-humidity usage environment, if the toner contains moisture, the moisture contained in the toner may evaporate due to heat when the toner is fixed under heat and pressure, leaving room for improvement in the gloss uniformity of the image caused by water vapor. In a fixing member in which the surface roughness of the surface layer is high in the longitudinal center and low at the longitudinal ends as in Patent Document 2, it is expected that water vapor generated when the toner melts in the longitudinal center, which is the image area, can escape through the unevenness of the surface, thereby suppressing gloss unevenness in the image, while at the longitudinal ends, slippage with the pressure roller can be suppressed by tight contact with the pressure roller.

[0008] As a method for manufacturing such a fixing member, as proposed in Patent Document 2, when cooling and crystallizing the PFA that forms the surface layer of the fixing member from a molten state, there is a method in which the cooling rate is increased only at the edges to reduce the size of the PFA crystals. However, when crystallizing PFA using this method, there is room for improvement in the abrasion resistance of the longitudinal edge regions. Therefore, the present inventors recognized that there is still room for improvement in achieving both abrasion resistance of the fixing member against paper and image quality.

[0009] The present disclosure provides an electrophotographic member that can obtain good image quality with high image gloss while improving the abrasion resistance of the surface layer against paper.The present disclosure also provides a heat fixing device that can obtain good image quality with high image gloss while improving the abrasion resistance of the surface layer against paper, and an electrophotographic image forming apparatus equipped with the heat fixing device. [Means for solving the problem]

[0010] The present disclosure provides: A fixing member having an endless shape, At least a base layer, an elastic layer, and a surface layer in this order; the surface layer contains crystals of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), When the total width of the fixing member in the longitudinal direction perpendicular to the circumferential direction is defined as L, a region of the fixing member extending from the midpoint of the fixing member in the longitudinal direction toward both ends to a position of 0.35×L is defined as a central region A, and regions of the fixing member extending from both ends of the longitudinal direction toward the midpoint to a position of 0.15×L are defined as end regions B, a surface SA of the central region A and a surface SB of the end region B that constitute the outer surface of the fixing member are each roughened by the crystals, When the arithmetic mean roughness of the surface SA is RaA and the arithmetic mean roughness of the surface SB is RaB, the following formula (1) is satisfied: RaA>RaB (1) The fixing member is characterized in that, when a sample taken from the surface layer in the end region B is measured using a differential scanning calorimeter (DSC) at a temperature rise rate of 20°C / min, the amount of heat absorbed during the temperature rise process is 21 J / g or more in the endothermic curve. The present disclosure also provides 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, The fixing member is the above-mentioned fixing member, which is a heat fixing device. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to provide a fixing member that can obtain high image gloss and good image quality while improving abrasion resistance against paper. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view schematically illustrating a color electrophotographic printer, which is an example of an electrophotographic image forming apparatus. [Figure 2] 1 is a cross-sectional view schematically illustrating a general configuration of a heat fixing device. [Figure 3] FIG. 2 is a cross-sectional view schematically illustrating the structure of a fixing film. [Figure 4] 3 is a diagram illustrating a central region A and an end region B of the fixing member. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] In this specification, unless otherwise specified, the expressions "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints. Furthermore, when a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined. Hereinafter, embodiments of the present disclosure will be described in detail. Note that the technical scope of the present disclosure is not limited to the following description.

[0014] <One embodiment> One embodiment is for a fuser member. The fixing member of the present disclosure comprises: A fixing member having an endless shape, At least a base layer, an elastic layer, and a surface layer in this order; the surface layer contains crystals of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), When the total width of the fixing member in the longitudinal direction perpendicular to the circumferential direction is defined as L, a region of the fixing member extending from the midpoint of the fixing member in the longitudinal direction toward both ends to a position of 0.35×L is defined as a central region A, and regions of the fixing member extending from both ends of the longitudinal direction toward the midpoint to a position of 0.15×L are defined as end regions B, a surface SA of the central region A and a surface SB of the end region B that constitute the outer surface of the fixing member are each roughened by the crystals, When the arithmetic mean roughness of the surface SA is RaA and the arithmetic mean roughness of the surface SB is RaB, the following formula (1) is satisfied: RaA>RaB (1) A sample taken from the surface layer in the end region B is measured using a differential scanning calorimeter (DSC) at a heating rate of 20°C / min, and the endothermic curve shows an endothermic amount of 21 J / g or more during the heating process. The explanation is given below.

[0015] <Electrophotographic image forming apparatus> 1 is a cross-sectional view of a color electrophotographic printer, which is an example of an electrophotographic image forming apparatus (hereinafter also referred to as an "image forming apparatus") according to this embodiment, taken along the conveyance direction of a recording material. In this embodiment, the color electrophotographic printer is simply referred to as a "printer."

[0016] 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 (photoconductor) 11 is pre-charged by a charger 12. The photosensitive drum 11 is then exposed by a laser scanner 13, and an electrostatic latent image is formed on it.

[0017] The electrostatic latent image is developed into a toner image by a developing unit 14. The toner image on the photosensitive drum 11 is sequentially transferred onto an image carrier, such as an intermediate transfer belt 31, by a primary transfer blade 17. 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.

[0018] Meanwhile, recording materials P are fed one by one from a paper feed cassette 20 or a multi-paper feed tray 25 in the direction of arrow 3 and fed into a pair of registration rollers 23. The pair of registration rollers 23 temporarily receives the recording material P and straightens it out if it is skewed.

[0019] The registration roller pair 23 then synchronizes with the toner image on the intermediate transfer belt 31 and feeds the recording material P between the intermediate transfer belt 31 and the secondary transfer roller 35. The color toner image on the intermediate transfer belt is transferred onto the recording material P by a transfer body, such as the secondary transfer roller 35. Thereafter, the toner image on the recording material P is fixed to the recording material P by the recording material P being heated and pressed by a heat fixing device 40.

[0020] The electrophotographic image forming apparatus includes a heat fixing device 40. The heat fixing device of the present disclosure is the heat fixing device 40 in the electrophotographic image forming apparatus, and the heat fixing device 40 includes a heating body, a fixing member that rotates and slides 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.

[0021] Next, a heat fixing device in an electrophotographic image forming apparatus will be described. The heat fixing device includes a fixing member and a pressure member disposed opposite the fixing member. FIG. 2 is a schematic diagram of a heat fixing device 40, showing an example of a film heating type heating device (tensionless type). This type of heating device was used in this example, but a roller pair type or film type heating device can also be used.

[0022] Reference numeral 43 denotes a ceramic heater (hereinafter referred to as heater) as a heating element. The 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. The heater 43 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. It is also configured to switch the energized area depending on the longitudinal width size of the recording material.

[0023] An electrophotographic member according to at least one embodiment of the present disclosure can be used, for example, as a fixing member. The fixing film 41 is a cylindrical (endless) heat-resistant fixing member that serves as a heating member for transmitting heat, and is loosely fitted around a support member (heater holder) 46 that includes the heater 43. The structure of the fixing film 41 is as shown in FIG. 3, and the fixing film has a three-layer composite structure that includes at least a surface layer 41a, an elastic layer 41c, and a base layer 41b.

[0024] The pressure roller 44 is a heat-resistant elastic pressure roller serving as a pressure member, and has a core metal and an elastic layer made of heat-resistant rubber such as silicone rubber or fluororubber, or a silicone rubber foam. Both ends of the core metal are rotatably supported by bearings.

[0025] The fixing film 41 and heater 43 are arranged above the pressure roller 44 in parallel with the pressure roller 44, and are pressed by a pressing member (not shown). In this way, the lower surface of the heater 43 and the upper surface of the pressure roller 44 are pressed against each other via the fixing film 41 against the elasticity of the elastic layer, thereby forming a fixing nip portion of a predetermined width as a heating portion.

[0026] The pressure roller 44 is driven to rotate at a predetermined peripheral speed in the counterclockwise direction indicated by the arrow 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 as a rotational force on the cylindrical fixing film 41. The fixing film 41 then slides in close contact with the downward surface of the heater 43, rotating clockwise as indicated by the arrow. The support member (heater holder) 46 also serves as a rotation guide for the fixing film 41.

[0027] The pressure roller 44 is driven to rotate, and the cylindrical fixing film 41 is driven to rotate accordingly, and the heater 43 is energized, causing the heater to heat up quickly to a predetermined temperature and enter a temperature-regulated state. In this state, the recording material P carrying the unfixed toner image T is introduced between the fixing film 41 and the pressure roller 44 in the fixing nip portion.

[0028] Then, in the fixing nip portion, the toner image-carrying side of the recording material P comes into close contact with the outer surface of the fixing film 41, and the recording material P is sandwiched and conveyed to the fixing nip portion together with the fixing film 41. During this sandwiching 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 heated and pressed onto the recording material P, melting and fixing it. Having passed through the fixing nip portion, the recording material P is separated by curvature from the surface of the fixing film 41 and is conveyed to be discharged.

[0029] 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 that has been heated to a high temperature.

[0030] At least one embodiment of the electrophotographic member of the present disclosure is, for example, a fixing member. For example, the electrophotographic member is a fixing belt. The electrophotographic member (fixing member) of the present disclosure has an endless shape and has at least a base layer, an elastic layer, and a surface layer in this order. That is, the electrophotographic member has a base layer, an elastic layer on the base layer, and a surface layer on the elastic layer. If necessary, other layers may be provided between the base layer, the elastic layer, and the surface layer, and on the inner peripheral surface side of the base layer and the outer peripheral surface side of the surface layer.

[0031] As shown in FIGS. 2 and 3, the fixing member is, for example, a fixing film 41. The fixing member (fixing film 41) has a base layer 41b, an elastic layer 41c, and a surface layer 41a. The surface layer 41a can be a release layer that has releasability for toner, for example. The surface layer 41a can form the outer surface of the electrophotographic member. The surface layer 41a may be adhered to the surface of the elastic layer 41c by an adhesive layer (not shown). An inner sliding layer (not shown) may be provided on the inner peripheral surface of the base layer 41b.

[0032] Each layer will be specifically described below. <base layer> The material of the base layer 41b is not particularly limited and may be any known electrophotographic material. Examples include metals and alloys such as aluminum, iron, stainless steel (SUS), and nickel, as well as heat-resistant resins such as polyimide. Stainless steel is preferred. The thickness of the base layer 41b is not particularly limited, but is preferably 20 μm to 100 μm, more preferably 20 μm to 50 μm, from the viewpoints of strength, flexibility, and heat capacity.

[0033] The outer surface of the base layer 41b 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.

[0034] When the elastic layer 41c containing silicone rubber is provided on the surface of the base layer 41b, it is preferable to apply a primer treatment to the surface of the base layer 41b in order to improve the adhesion between the base layer 41b and the elastic layer 41c. Examples of the primer used for the primer treatment include paints 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.

[0035] The primer can be appropriately selected depending on the material of the base layer 41b, the type of the elastic layer 41c, or the type of crosslinking reaction. In particular, when the elastic layer 41c 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 41c contains a large amount of hydrosilyl groups, a primer containing an unsaturated aliphatic group is preferably used.

[0036] Other examples of primers include those containing alkoxy groups. Commercially available primers can be used. The primer treatment includes a step of applying the primer to the outer surface of the base layer 41b (the surface to be bonded to the elastic layer 41c) and drying or baking the primer.

[0037] <Inner sliding layer> An inner sliding layer may be provided on the inner peripheral surface side of the base layer 41b. A resin having both high durability and high heat resistance, such as polyimide resin, is suitable for the inner sliding layer. Since the inner sliding layer gradually wears away due to friction, it is preferable to provide a thickness that is sufficient to allow it to function as a sliding layer throughout use. On the other hand, a thickness that does not interfere with the supply of heat from the heater is preferable. Therefore, the thickness is preferably 5 μm or more and 20 μm or less, and more preferably 10 μm or more and 15 μm or less. The inner sliding layer may be formed using a known coating method or the like.

[0038] <Elastic layer> The elastic layer 41c may be made of any known electrophotographic material, and is not particularly limited. The elastic layer 41c preferably contains silicone rubber, which has excellent heat resistance. An addition-curing liquid silicone rubber is preferably used as the raw material for the silicone rubber. The elastic layer 41c may be formed, for example, by applying addition-curing liquid silicone rubber to the outer surface of the base layer 41b and then heat-curing it. The application method is not particularly limited, and any known method may be used.

[0039] The thickness of the elastic layer 41c can be appropriately designed taking into consideration the surface hardness of the fixing member and the width of the fixing nip portion to be formed, and is preferably 100 μm to 500 μm, more preferably 200 μm to 400 μm.

[0040] As the silicone rubber, for example, a cured product of an addition-curing liquid silicone rubber composition described below can be used. The elastic layer 41c can be formed by applying and heating the liquid silicone rubber composition by a known method.

[0041] The liquid silicone rubber composition generally contains the following components (a) to (d): Component (a): organopolysiloxane having an unsaturated aliphatic group Component (b): Organopolysiloxane having silicon-bonded active hydrogen Component (c): Catalyst Component (d): Thermally conductive filler

[0042] Each component will be described below. (Component (a)) The organopolysiloxane having an unsaturated aliphatic group is an organopolysiloxane having an unsaturated aliphatic group such as a vinyl group, and examples thereof include those represented by the following formulas (C1) and (C2). The organopolysiloxane having an unsaturated aliphatic group is preferably a linear type. [ka] In formula (C1), m 1 indicates an integer of 0 or greater, and n 1 represents an integer of 3 or more. In addition, in formula (C1), R 1 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group, provided that R 1 At least one of R represents a methyl group. 2 each independently represents an unsaturated aliphatic group.

[0043] [ka] In formula (C2), n 2 denotes a positive integer, and R 3 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group, provided that R 3 At least one of R represents a methyl group. 4 each independently represents an unsaturated aliphatic group.

[0044] In formula (C1) and formula (C2), R 1 and R 3Examples of the monovalent unsubstituted or substituted hydrocarbon group containing no unsaturated aliphatic group that can be represented by include the following groups: Unsubstituted hydrocarbon groups Alkyl groups (e.g., methyl, ethyl, propyl, butyl, pentyl, hexyl) aryl groups (e.g., phenyl groups) Substituted hydrocarbon groups Substituted alkyl groups (e.g., chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, 3-cyanopropyl, 3-methoxypropyl)

[0045] The organopolysiloxanes represented by formula (C1) and formula (C2) have at least one methyl group directly bonded to the silicon atom forming the chain structure. However, for ease of synthesis and handling, R 1 and R 3 Preferably, 50% or more of each group is a methyl group, and all of the R 1 and R 3 is more preferably a methyl group.

[0046] In addition, in formula (C1) and formula (C2), R 2 and R 4 Examples of unsaturated aliphatic groups that can be represented by include the following groups. That is, examples of unsaturated aliphatic groups include vinyl groups, allyl groups, 3-butenyl groups, 4-pentenyl groups, and 5-hexenyl groups. Among these groups, R 2 and R 4 is preferably a vinyl group.

[0047] From the viewpoint of moldability, the viscosity of component (a) is 1000mm 2 / s or more 50000mm 2 / s or less is preferable. 2 If the hardness is lower than 50,000 mm / s, it becomes difficult to adjust the hardness required for the elastic layer 41c. 2If the viscosity is higher than 1 / s, the viscosity of the composition will be too high, making it difficult to apply. Viscosity (kinematic viscosity) can be measured using a capillary viscometer or rotational viscometer in accordance with JIS Z 8803:2011.

[0048] The blending amount of component (a) is preferably 55% by volume or more from the viewpoint of durability and 65% by volume or less from the viewpoint of heat transfer, based on the liquid silicone rubber composition used to form elastic layer 41c.

[0049] (ingredient (b)) The organopolysiloxane having silicon-bonded active hydrogen atoms functions as a crosslinker that reacts with the unsaturated aliphatic groups of component (a) under the action of a catalyst to form a cured silicone rubber.

[0050] Any organopolysiloxane having a Si-H bond can be used as component (b). In particular, from the viewpoint of reactivity with the unsaturated aliphatic group of component (a), those having an average of three or more hydrogen atoms bonded to silicon atoms per molecule are preferably used.

[0051] Specific examples of component (b) include the linear organopolysiloxane shown by the following formula (C3) and the cyclic organopolysiloxane shown by the following formula (C4). [ka] In formula (C3), m 2 indicates an integer of 0 or greater, and n 3 represents an integer of 3 or more, and R 5 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group. [ka] In formula (C4), m 3 indicates an integer of 0 or greater, and n 4 represents an integer of 3 or more, and R 6 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group.

[0052] R in formula (C3) and formula (C4) 5 and R 6 Examples of the monovalent unsubstituted or substituted hydrocarbon group not containing an unsaturated aliphatic group that can be represented by R 1 Among these, R 5 and R 6 Preferably, 50% or more of each group is a methyl group, and all of the R 5 and R 6 is more preferably a methyl group.

[0053] (component (c)) Examples of catalysts used in forming silicone rubber include hydrosilylation catalysts for accelerating the curing reaction. Known substances such as platinum compounds and rhodium compounds can be used as the hydrosilylation catalyst. The amount of catalyst used can be appropriately determined and is not particularly limited.

[0054] (ingredient (d)) The elastic layer 41c may contain a filler. The filler is added to control the thermal conductivity, heat resistance, and elastic modulus. Examples of the thermally conductive filler include metals, metal compounds, and carbon fibers. Highly thermally conductive fillers are more preferable, and specific examples thereof include the following materials:

[0055] Examples include metal silicon (Si), silicon carbide (SiC), silicon nitride (Si3N4), boron nitride (BN), aluminum nitride (AlN), alumina (Al2O3), iron oxide (Fe2O3), zinc oxide (ZnO), magnesium oxide (MgO), titanium oxide (TiO2), silica (SiO2), copper (Cu), aluminum (Al), silver (Ag), iron (Fe), nickel (Ni), carbon black (C), carbon nanotubes (C), vapor-grown carbon fiber, PAN-based (polyacrylonitrile) carbon fiber, and pitch-based carbon fiber.

[0056] <Adhesive layer> An adhesive layer may be provided between the elastic layer 41c and the surface layer 41a to bond them together. The material of the adhesive layer is not particularly limited, and known materials may be used. The adhesive layer preferably contains a silicone rubber adhesive. The thickness of the adhesive layer is not particularly limited, but is preferably 1 μm or more and 20 μm or less, and more preferably 3 μm or more and 10 μm or less.

[0057] <Surface layer> The fixing member of the present disclosure has a surface layer 41a containing tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). The surface layer 41a is preferably made of PFA. A plurality of PFA crystals of different sizes are exposed on the outer surface of the surface layer. Furthermore, at least a portion of the outer surface of the fixing member is made up of the surfaces of the crystals and is roughened by the crystals. The chemical composition of the surface layer, etc., can be confirmed, for example, by nuclear magnetic resonance (NMR).

[0058] As shown in Figure 4, the fixing member of the present disclosure has a surface layer with a plurality of crystals of different sizes exposed in the central region 41aA and the end region 41aB of the outer surface. The central region A and the end region B are defined as follows: L is the overall width in the longitudinal direction perpendicular to the circumferential direction of the fixing member, and the region extending from the midpoint of the fixing member to both ends of the length 0.35 x L is defined as a central region A. The end region B is defined as the region extending from both ends of the fixing member to the midpoint of the length 0.15 x L. The surface SA of the central region A and the surface SB of the end region B, which constitute the outer surface of the fixing member, are each formed of the crystal surfaces and roughened by the crystals. However, it is sufficient that at least a portion of the outer surface of the fixing member is formed of the crystal surfaces and roughened by the crystals.

[0059] Ten observation areas are randomly arranged in each of the central region A and the edge region B on the outer surface of the fixing member. The arithmetic mean roughness Ra is measured in each observation area with a measurement line length of 1.25 mm. In the fixing member of the present disclosure, when the average of the arithmetic mean roughness Ra at 10 points on the surface SA of the central region A is RaA and the average of the arithmetic mean roughness Ra at 10 points on the surface SB of the edge region B is RaB, RaA and RaB satisfy the relationship of the following formula (1): RaA>RaB (1)

[0060] A sample taken from the end region 41aB (surface layer in end region B) on the outer surface of the fixing member is used as a measurement sample, and measurement is performed once using a differential scanning calorimeter (DSC) at a temperature increase rate and a temperature decrease rate of 20°C / min. In the endothermic curve obtained in this measurement, the fixing member of the present disclosure has an endothermic amount of 21 J / g or more during the first temperature increase process.

[0061] The reason why a fixing member having such a surface layer can satisfy all of the requirements, including abrasion resistance against paper, high image gloss, and good image quality, will be explained below along with an explanation of each configuration of the surface layer. PFA is a copolymer of perfluoroalkyl vinyl ether (PAVE) and tetrafluoroethylene (TFE). The surface layer 41a containing PFA can be formed by coating the surface of the elastic layer 41c with a dispersion (water-based dispersion paint) or powder paint containing PFA as the main component, and then heating the coating to above its melting point to form a film. Alternatively, a PFA tube manufactured by extrusion molding can be used to cover the surface of the elastic layer 41c. The surface layer 41a can be, for example, a PFA tube.

[0062] The PFA is not particularly limited, and known PFAs can be used. Commercially available PFAs may be used. Specific examples include AP-230 (trade name, manufactured by Daikin Industries, Ltd.) and AP-231SH (trade name, manufactured by Daikin Industries, Ltd.).

[0063] The PFA can be identified by, for example, the presence of a peak characteristic of polytetrafluoroethylene (PTFE) in the FT-IR ATR spectrum, as well as the presence of a peak at 994 cm , which does not appear in PTFE. -1 This can be confirmed by checking for the presence of a small peak nearby.

[0064] First, the characteristic peak of PTFE is 1200 cm -1 (CF2 antisymmetric stretching), 1150cm -1 (CF2 symmetrical expansion), 640cm -1 (CF2 out-of-plane bending angle (wagging)), 555cm -1 (CF2 in-plane angle change (scissors)), 505cm -1 (CF2 in-plane deflection (rocking)).

[0065] In addition, the characteristic of PFA is 994cm -1 The position of the peak around 994 cm varies depending on the length of the carbon chain of the perfluoroalkyl vinyl ether moiety. -1 In the case of the perfluoroethoxy group, it appears at 1090 cm -1 In the case of the perfluoromethoxy group, it appears at 881 cm -1 Appears in.

[0066] When the total width of the fixing member in the longitudinal direction is L, the arithmetic mean roughness RaA of the surface of the central region A, which is 0.35 x L from the midpoint in the longitudinal direction to both ends, is large. This allows the water vapor generated when the toner that has absorbed moisture in the HH environment melts to escape through the unevenness in the central region through which the toner-carrying recording material passes, thereby suppressing uneven gloss of the image caused by the water vapor. When the total width of the fixing member in the longitudinal direction is L, the arithmetic mean roughness RaB of the surface of the edge region B, which is 0.15 x L from both ends to the midpoint, is small. This increases the true contact area in the nip with the pressure member and increases the coefficient of friction.

[0067] This suppresses microslip with the pressure member, and image misalignment due to microslip in the central and edge regions perpendicular to the recording material conveyance direction can be suppressed. Furthermore, suppressing microslip between the fixing member and pressure member also has the effect of suppressing wear between the recording material and the fixing member. Therefore, by making the arithmetic mean roughness RaA of the central region and the arithmetic mean roughness RaB of the edge regions satisfy the relational expression (1), it is possible to suppress uneven gloss and misalignment of the image, and to obtain good image quality and wear resistance.

[0068] It is more preferable that the relationship between RaA and RaB satisfies the following (2). RaA-RaB≧0.03 (2) The fixing member of the present disclosure preferably has an RaA of 0.15 μm or more and 0.22 μm or less, and more preferably 0.24 μm or less. When the RaA is in the range of 0.15 μm or more, the surface has large irregularities, allowing water vapor to escape easily when the toner melts, and gloss unevenness is likely to be effectively suppressed. Furthermore, when the RaA is in the range of 0.22 μm or less, the surface smoothness is better and the actual contact area between the recording material and the fixing member is large, making it less likely that toner melting unevenness will occur and gloss unevenness will be effectively suppressed.

[0069] In the fixing member of the present disclosure, the surfaces SA and SB preferably have different surface roughnesses due to the area-average diameter of the crystals, and the RaB is preferably 0.06 μm or more and 0.13 μm or less. When the RaB is 0.06 μm or more, the amorphous portion of the PFA present in the gaps between the lamellar structure of the crystalline spherulites is reduced, suppressing a decrease in crystallinity and improving wear resistance. Furthermore, when the RaB is 0.13 μm or less, the actual contact area at the nip with the pressure member is reduced, which tends to effectively suppress slippage.

[0070] In the fixing member of the present disclosure, it is preferable that the area-average diameter of the crystals in at least one of the observation areas included in the central region A is 25 μm or more and 40 μm or less, and it is also preferable that the area-average diameter of the crystals in at least one of the observation areas included in the edge region B is 5 μm or more and 20 μm or less.

[0071] In the fixing member of the present disclosure, the area average diameter DA of the spherulites of the PFA contained in the surface layer in the central region A of the surface layer is more preferably 25 μm or more and 40 μm or less, and the area average diameter DB of the spherulites in the edge region B of the surface layer is more preferably 5 μm or more and 20 μm or less. By doing so, the fixing member of the present disclosure can obtain higher image gloss and better image quality while improving abrasion resistance with paper.

[0072] The fixing member of the present disclosure preferably has a surface layer 41a having a thickness of 10 μm or more and 30 μm or less. When the thickness of the surface layer 41a is 30 μm or less, the influence of the nucleating agent on the inner surface side of the surface layer on the RaB becomes greater, making it easier to reduce the size of PFA spherulites, thereby better suppressing slippage of the recording medium. When the thickness of the surface layer 41a is 10 μm or more, it makes it easier to increase the size of PFA spherulites, making it easier to improve the escape of water vapor during toner melting in an HH environment. The thickness of the surface layer is more preferably 15 μm or more and 30 μm or less.

[0073] In addition, a plurality of PFA crystals of different sizes are exposed on the outer surface of the surface layer in the central region and the edge region, and at least a portion of the outer surface of the fixing member is made up of the surfaces of the crystals and is roughened by the crystals.

[0074] This allows the outer surface of the fixing member to remain roughened over long periods of use, allowing water vapor to escape in the central region when the toner melts, and preventing the recording medium from slipping in the edge regions, resulting in good image quality.

[0075] The roughened surface caused by crystals is when PFA spherulites are formed on the outer surface, and the unevenness is formed along the spherulite shape. The larger the spherulite diameter, the larger the unevenness. The unevenness formed along the spherulite shape is difficult to flatten due to the heat and pressure during fixing, and the unevenness can be maintained over long periods of use.

[0076] The method for confirming that the surface is roughened with PFA crystals is as follows. Two observation areas of 1200 μm × 1600 μm are set up in each of the central region A and edge region B, and the area mean diameter of the spherulites is calculated using the method described below. The correlation coefficient R between the arithmetic mean roughness Ra and the area mean diameter D calculated using the method described below is found for each observation area, and when R is +0.90 or greater, it is determined that the surface is roughened by crystals.

[0077] A method for forming PFA spherulites on the outer surface can be, for example, during the manufacturing process of the fixing member, by forming the surface layer 41a, heating it to a temperature above the melting point of PFA, and then cooling it to crystallize the PFA and form spherulites. Although the specific method is not particularly limited, the following methods for heat treatment of the surface layer can be used.

[0078] After forming the surface layer, an upright cylindrical heating cylinder capable of heating up to, for example, 330°C or higher is used to heat the entire electrophotographic member. 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 surface layer to reach the desired temperature, and may be, for example, 1 to 20 minutes, 1 to 10 minutes, or 2 to 5 minutes.

[0079] A sample taken from the edge region 41aB is used as the measurement sample, and a differential scanning calorimeter (DSC) is used to measure the temperature at both a heating rate and a cooling rate of 20°C / min. The amount of heat absorbed during the first heating process in the DSC measurement is the amount of heat absorbed due to crystalline melting of PFA. The crystallinity of PFA can be calculated by dividing the amount of heat absorbed by the heat of complete crystalline melting of PFA (92.9 J / g). An endothermic amount of 21 J / g or more provides good abrasion resistance to paper. It is even more preferable that the amount of heat absorbed during the heating process be 24 J / g or more.

[0080] One method for achieving a heat absorption of 21 J / g or more is to heat the surface layer 41a to a temperature above the melting point of PFA after forming it during the manufacturing process of the fixing member, and then promote crystallization of the PFA by controlling the cooling rate.

[0081] After forming the surface layer, the surface layer 41a is heated to 330°C or higher using the heating barrel as described above to heat the entire electrophotographic member, and the cooling rate of the heating barrel is then 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 faster the cooling rate in the PFA crystallization temperature range, the smaller the PFA spherulite diameter. The cooling rate is preferably controlled until the temperature of the edge region 41aB falls below the PFA crystallization temperature range. The cooling rate may be within a range that allows the PFA spherulite diameter to be controlled to the desired size, for example, 8 to 60°C / min.

[0082] The specific method for controlling RaA and RaB is not particularly limited, but an example is a method for controlling the area mean diameter of PFA spherulites on the outer surface. This method is described below.

[0083] It is believed that the area mean diameter of PFA spherulites decreases as the frequency of spherulite nuclei increases relative to the PFA crystal growth rate. For example, to reduce the area mean diameter of spherulites on the outer surface, one method is to increase the cooling rate in the PFA crystallization temperature range, as described above. Another method is to place a substance that acts as a nucleating agent for spherulites on the inner side of the surface layer 41a, i.e., near the surface facing the elastic layer. This increases the frequency of spherulite nuclei on the inner side.

[0084] Spherulites grow from spherulite nuclei and stop growing when they come into contact with other spherulites. Therefore, if the frequency of spherulite nuclei is high, the diameter of the spherulites formed on the inner surface side becomes smaller. In the surface layer 41a, the smaller the diameter of the spherulites formed on the inner surface side, the smaller the diameter of the spherulites on the outer surface. This is thought to be because spherulites first form on the inner surface side, and then molecules adhere to the surface, causing crystallization to progress toward the outer surface. Therefore, if the frequency of spherulite nuclei is high on the inner surface side, the area-average diameter of the spherulites on the outer surface tends to be small. Conversely, if the frequency of spherulite nuclei is low on the inner surface side, the area-average diameter of the spherulites on the outer surface tends to be large.

[0085] To create a nucleating agent on the inner surface of the surface layer, for example, a PFA tube is used to create the surface layer 41a, and the inner surface is irradiated with excimer laser light under controlled irradiation conditions. During excimer laser treatment, fluorine atoms on the inner surface of the PFA tube are released, resulting in reactions such as carbonization and the generation of carbonyl groups through reactions with oxygen. This results in a change in the elemental ratio on the inner surface. The resulting carbon becomes a nucleating agent, allowing this method to create a nucleating agent on the inner surface.

[0086] As described above, in the surface layer containing PFA, the outer surface of the surface layer is roughened with PFA crystals, and by satisfying RaA>RaB, water vapor generated when the toner melts can be released in the central region over long periods of use, suppressing uneven gloss, while slippage of the recording medium can be suppressed in the edge regions, resulting in good image quality.

[0087] When a fixing film is manufactured by a conventional method, the area-average diameter of the spherulites is uniform in the longitudinal direction, and RaA and RaB are equal. As a specific method for making RaA>RaB, the following method can be used. Here, an example is given in which a PFA tube is used to fabricate surface layer 41a, but the surface layer according to the present disclosure is not limited to one formed using a PFA tube.

[0088] 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 crystallization, resulting in the crystals being oriented in the extrusion direction. The PFA tube is then coated on the surface of the elastic layer 41c to form the surface layer 41a, and the surface layer is then heat-treated to form spherulites on the surface of the surface layer. In this process, it is preferable to control the cooling rate within the crystallization temperature range of the PFA to control the spherulite diameter.

[0089] The inner surface of the PFA tube can be preliminarily treated with sodium, excimer laser, ammonia, or the like to improve wettability and adhesion to the elastic layer 41c or an adhesive layer that is provided as needed. It is preferable to treat the inner surface of the PFA tube using excimer laser treatment.

[0090] For the excimer laser treatment, it is preferable to attach a compound that absorbs ultraviolet light to the inner surface of the PFA tube, and then irradiate it with ultraviolet laser light such as KrF excimer laser light or ArF excimer laser light. Known compounds that absorb ultraviolet light can be used. For example, an aqueous solution is prepared by mixing a compound that absorbs ultraviolet light, such as sodium benzoate, with a known fluorosurfactant, and the aqueous solution is applied to the inner surface of the PFA tube and allowed to dry naturally.

[0091] During excimer laser treatment, fluorine atoms on the inner surface of the PFA tube are released, causing reactions such as carbonization and the generation of carbonyl groups through reactions with oxygen. As a result, the element ratio on the inner surface changes. The carbon generated by this process acts as a nucleating agent, allowing the nucleating agent to exist on the inner surface.

[0092] In this disclosure, the irradiation conditions of the excimer laser beam are controlled to control the carbonization of the inner surface of the PFA tube, thereby controlling the amount of carbon on the surface of the surface layer facing the elastic layer, thereby producing an electrophotographic member in which the surface roughness of the surface layer has a distribution in the longitudinal direction. The irradiation conditions of the excimer laser beam are usually selected from the viewpoint of improving wettability and adhesiveness, and the irradiation amount per shot or the number of shots is adjusted.

[0093] In the present disclosure, it is preferable to create areas with a high number of shots and areas with a low number of shots by varying the timing of the process of attaching a compound that absorbs excimer laser light to the inner surface between the longitudinal center and the longitudinal ends, thereby controlling the amount of carbon on the inner surface of the PFA tube for each area.

[0094] In the end regions where the number of shots is high, the amount of carbon on the inner surface of the PFA tube is high, which makes it easier to reduce the area mean diameter of the PFA spherulites on the outer surface of the surface layer. The number of shots in this case is preferably 6 to 10, more preferably 6 to 8. In the center region where the number of shots is low, the amount of carbon on the inner surface of the PFA tube is low, which makes it easier to increase the area mean diameter of the PFA spherulites on the outer surface of the surface layer.

[0095] The number of shots in this case is preferably 2 or more and 6 or less, more preferably 4 or more and 6 or less. However, in order to satisfy the relationship that the arithmetic mean roughness RaA of the central part is larger than the arithmetic mean roughness RaB of the edge part, the number of shots at the edge part must be larger. In addition, the irradiation dose of the excimer laser light is preferably 100 mJ / cm. 2 / pulse over 600mJ / cm 2 / pulse or less, more preferably 200 mJ / cm2 / pulse over 400mJ / cm 2 / pulse or less.

[0096] Furthermore, the thickness of the surface layer 41a is preferably 30 μm or less. When the thickness is 30 μm or less, the influence of the nucleating agent on the inner surface side of the surface layer on the area average diameters DA and DB becomes greater, making it easier to control the spherulite diameters in the central region A and the edge region B. The thickness of the surface layer 41a is more preferably 10 μm or more and 25 μm or less.

[0097] The method for covering the surface of the elastic layer with the PFA tube is not particularly limited, and known methods can be used. For example, a method of expanding a fluororesin tube from the outside to cover it (expansion covering method) can be used. A vacuum expansion covering method can be used, in which the PFA tube is vacuum expanded from the outside to cover it.

[0098] The methods for measuring each physical property in the present disclosure are shown below. <Method for measuring the arithmetic mean roughness RaA and RaB of the outer surface of the surface layer> Ten observation areas are randomly arranged in each of the central region A and the edge region B on the outer surface of the fixing member. The observation areas are measured using a shape analysis laser microscope (product name: VK-X150, manufactured by Keyence Corporation) according to a method conforming to JIS B0633:2001. Using the shape measurement mode and a 20x objective lens, a shape measurement image of the outermost surface of the transparent body is obtained. A measurement line 1.25 mm long and parallel to the longitudinal direction of the fixing member is placed in the center of the shape measurement image, and the arithmetic mean roughness Ra is measured with a cutoff wavelength λc of 0.25 mm.

[0099] The average value of the arithmetic mean roughness Ra measured at 10 points within the central region A using the above method was defined as RaA, and the average value of the arithmetic mean roughness Ra measured at 10 points within the edge region B was defined as RaB.

[0100] <Method for measuring endothermic heat> First, the surface layer is isolated from the electrophotographic member. Specifically, the surface layer is peeled off from the base layer along with the elastic layer, and the elastic layer bonded to the surface layer is dissolved in a solvent to isolate only the surface layer. The isolated surface layer is cut into a piece approximately 2 mm x 2 mm so that it fits into the DSC measurement pan.

[0101] 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 for temperature correction of the detector, and the heat of fusion of indium is used for heat correction. Specifically, 4 mg of the surface layer is precisely weighed and placed in an aluminum pan. An empty aluminum pan is used as a reference. Measurements are performed in the measurement range of 25°C to 400°C at a heating rate of 20°C / min. The measurement is performed by heating from room temperature to 400°C, holding for 5 minutes, and then cooling to 25°C at a rate of 20°C / min. During the temperature rise process, the area enclosed by the temperature-endothermic curve including the endothermic peak and the baseline is taken as the endothermic amount.

[0102] <Method for measuring the area mean diameters DA and DB of spherulites> First, the surface layer is isolated from the electrophotographic member. Specifically, the surface layer is peeled off from the base layer along with the elastic layer, and the elastic layer attached to the surface layer is dissolved in a solvent to isolate only the surface layer. The outer surface of the isolated surface layer is then observed with a microscope (product name: ECLIPSE LV100NDA, manufactured by Nikon Corporation) to obtain an image of the spherulites. The observation conditions are as follows: switched to transmitted illumination, the analyzer and transmitted illumination polarizer are orthogonalized and adjusted to a crossed Nicol, and a 20x objective lens is used. Using a transmitted polarizing microscope, an image can be obtained that confirms the spherulite structure.

[0103] Next, the outlines of 200 spherulites are manually extracted from the obtained observation image of the spherulites. The extraction is performed by extracting the boundary line of each Maltese cross in the observation image as the outline of the spherulite, since each spherulite has a cross-shaped shadow called a Maltese cross. The area of ​​each spherulite is calculated using the image analysis software "ImageJ." The area-average diameters DA and DB of the spherulites are calculated from the areas of the 200 spherulites and the circle-equivalent diameters calculated from each area.

[0104] <Method for measuring the thickness of the surface layer> First, the surface layer is isolated from the electrophotographic member in the same manner as in the measurement of the endothermic peak temperature and endothermic amount, and the thickness of the isolated surface layer is measured using a micrometer (product name: High-Precision Digimatic Micrometer MDH-25MB, manufactured by Mitutoyo Corporation). [Example]

[0105] The present disclosure will be described in more detail below using examples and comparative examples, but the aspects of the present disclosure are not limited to these. Example 1 In this example, a fixing film as shown in FIG. 3 was prepared. (Inner surface treatment of PFA tube) A PFA tube with a total length of 400 mm and a thickness of 20 μm was used, which was obtained by extrusion molding Neoflon PFA: AP-231SH (manufactured by Daikin Industries, Ltd.) as the raw material. An aqueous solution (hereinafter referred to as the "modifier") containing 5% by mass of sodium benzoate and 1% by mass of Surflon S-113 (manufactured by AGC Seimi Chemical Co., Ltd.) was applied to the inner surface of the PFA tube within 82.5 mm of both ends of its longitudinal axis, and the tube was allowed to dry naturally.

[0106] Then, 300 mJ / cm2 for the PFA tube 2 The PFA tube was then irradiated with two shots of KrF excimer laser light at 1 / 1000 pulses. The modifier was then applied to the inner surface of the PFA tube over a 235 mm area at the center of the longitudinal direction, and air-dried again. After drying, the PFA tube was irradiated with 300 mJ / cm 2 2The inner surface of the PFA tube was treated with six shots of KrF excimer laser light at 1 / 1000 pulses, and the central region was treated with six shots and the end regions with eight shots.

[0107] (base layer) A stainless steel (SUS) substrate with an inner diameter of 24 mm and a thickness of 30 μm was used.

[0108] (Formation of inner sliding layer) First, a polyimide precursor solution was prepared by reacting approximately equimolar amounts of an aromatic tetracarboxylic dianhydride or its derivative with an aromatic diamine in an aprotic polar organic solvent. The resulting polyimide precursor solution was applied to the inner surface of the base layer by ring coating, and after drying the solvent in an electric furnace, the substrate was heated at 260-400°C for approximately 1 hour to form an inner sliding layer. The thickness of the inner sliding layer was 12 μm.

[0109] (Formation of primer layer and elastic layer) A primer layer and an elastic layer were formed on the base layer on which the inner sliding layer was formed by the following procedure. A hydrosilyl silicone primer (DY39-051 A / B; manufactured by Dow-Toray) was applied to the base layer and then heat-cured for 5 minutes at 200°C. A liquid addition-curable silicone rubber composition containing the following components (a) to (d) was applied to a thickness of 250 μm onto the primer layer and then heat-cured for 30 minutes at 200°C to form a 250 μm-thick elastic silicone rubber layer.

[0110] (Silicone rubber composition) Component (a): Linear organopolysiloxane having an unsaturated aliphatic group Component (b): Organopolysiloxane having silicon-bonded active hydrogen Component (c): Catalyst Component (d): Thermally conductive filler

[0111] First, 100 parts by mass of a silicone polymer having vinyl groups, which are unsaturated aliphatic groups, only at both ends of the molecular chain and methyl groups as unsubstituted hydrocarbon groups containing no other unsaturated aliphatic groups, was prepared as component (a). This silicone polymer (trade name: DMS-V35, manufactured by Gelest, viscosity 5000 mm) 2 / s) will be referred to as "Vi" from here on.

[0112] Next, 370 parts by mass of alumina (product name: Amina Beads CB-P10, manufactured by Showa Denko K.K.) was added to this Vi as component (d), and the mixture was placed in a planetary mixer (ARV-5000, manufactured by Thinky Corporation) and stirred and mixed at 600 rpm for 2 minutes to obtain mixture 1.

[0113] Next, a solution of 0.2 parts by mass of 1-ethynyl-1-cyclohexanol (manufactured by Tokyo Chemical Industry Co., Ltd.), a cure retarder, in the same weight of toluene was added to the mixture 1 to obtain a mixture 2.

[0114] Next, 0.1 parts by mass of a hydrosilylation catalyst (platinum catalyst: a mixture of 1,3-divinyltetramethyldisiloxane platinum complex, 1,3-divinyltetramethyldisiloxane, and 2-propanol) as component (c) was added to mixture 2 to obtain mixture 3.

[0115] Furthermore, as component (b), a silicone polymer (trade name: HMS-301, manufactured by Gelest, viscosity 30 mm) having a linear siloxane skeleton and silicon-bonded active hydrogen groups only on the side chains was used. 2 1.1 parts by mass of SiH (SiH / s, hereinafter referred to as "SiH") was weighed out. This was added to Mixture 3 and mixed thoroughly to obtain a liquid addition-curable silicone rubber composition.

[0116] (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.

[0117] (Formation of surface layer) After the adhesive was applied, the PFA tube, which had been subjected to the above-described inner surface treatment as a surface layer, was vacuum-expanded from the outside to cover the adhesive (vacuum expansion covering method). 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 cover 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 a heating method such as an electric furnace. Specifically, the workpiece was heated at 200°C for 2 minutes in an electric furnace. Both ends were then cut to the desired length (336.5 mm).

[0118] (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 set to 330°C, and the heat treatment was carried out so that the actual temperature of the surface layer was above the melting temperature of PFA.

[0119] 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's actual temperature to reach the desired heat treatment temperature. After 3 minutes had passed since the placement, 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 endothermic peak temperature in region B and the values ​​of RaA, RaB, DA, and DB of the prepared fixing film were determined. These results are shown in Table 1.

[0120] <Evaluation of changes in roughness before and after passing 20,000 sheets> The change in roughness before and after passing 20,000 sheets was evaluated by measuring the arithmetic mean roughness as described below using a film heating type heat fixing device 40 incorporating the prepared fixing film shown in Figure 2. First, a shape analysis laser microscope (product name: VK-X150, Keyence) was used to measure the arithmetic mean roughness RaA of the central region of the fixing film and the arithmetic mean roughness RaB of the edge region.

[0121] The fixing film was then installed into the heating and fixing device 40, and the pressure roller was rotated so that the surface movement speed (circumferential speed) of the pressure roller was 300 mm / sec, with the pressure applied to one end being 156.8 N and the total pressure applied being 313.6 N (32 kgf). 20,000 sheets of paper (A4 landscape, GF-C068) were passed through continuously while the surface temperature of the paper passing section of the fixing film was controlled to 170°C.

[0122] Thereafter, the fixing film was removed from the heat fixing device 40, and RaA and RaB were measured again using the shape analysis laser microscope (product name: VK-X150, Keyence), and the rate of change in RaA before and after continuous paper feed of 20,000 sheets and the rate of change in RaB before and after continuous paper feed of 20,000 sheets were calculated as follows. Rate of change in RaA = (RaA after 20,000 sheets have been passed - RaA before passing) / RaA before passing × 100 Rate of change in RaB = (RaB after 20,000 sheets passed - RaB before passing) / RaB before passing × 100

[0123] The smaller the absolute value of the rate of change in RaA and the absolute value of the rate of change in RaB, the less the surface shape changes due to paper passing, and the longer the effect lasts. If the evaluation score was 2 to 4 according to the following evaluation criteria, it was determined that the effect of the present disclosure was obtained. (Evaluation criteria) 4: After paper is fed, RaA>RaB is satisfied, and the sum of the absolute value of the rate of change of RaA and the absolute value of the rate of change of RaB is less than 15 3: After paper is fed, RaA>RaB is satisfied, and the sum of the absolute value of the rate of change of RaA and the absolute value of the rate of change of RaB is 15 or more and less than 25 2: After paper is fed, RaA>RaB is satisfied, and the sum of the absolute value of the rate of change of RaA and the absolute value of the rate of change of RaB is 25 or more. 1: RaA > RaB is not satisfied after paper is fed

[0124] <Overall image quality rating> The overall evaluation of image quality is performed by performing two evaluations: (a) evaluation of gloss uniformity in an HH environment, and (b) evaluation of image misalignment. The average of these evaluations is rounded down to the nearest whole number to obtain the overall evaluation of image quality. When the effects of both the surface roughness in the central region and the surface roughness in the edge region of the fixing member are realized, the overall evaluation of image quality is high. If this value is 2 to 3, it is determined that the effects of the present disclosure have been obtained.

[0125] (a) Gloss uniformity evaluation in HH environment The evaluation of image gloss in the HH environment was carried out using the same film-heating type heat fixing device 40 as used in the evaluation of changes in roughness before and after passing 20,000 sheets of paper. A black solid image was fixed in an environment (HH environment) with a temperature of 30°C and a relative humidity of 80%, with the surface temperature of the fixing film at the paper passing point controlled at 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 of 12 points randomly selected from the output image was measured using a gloss meter (a handy gloss meter PG-1M manufactured by Nippon Denshoku Industries Co., Ltd.), and the difference between the maximum and minimum values ​​was taken as ΔG and evaluated according to the following criteria.

[0126] 60° gloss is the glossiness measured at an incident angle of 60°. At an incident angle of 60°, glossiness is calculated by taking the specular reflectance (10%) of light from a glass surface layer with a refractive index of 1.567 across the entire visible wavelength range as 100. The greater the effect on image gloss due to evaporation of water vapor contained in the toner, the greater ΔG becomes. (Evaluation criteria) 3: ΔG is 1 or less 2: ΔG is greater than 1 and less than 3 1: ΔG exceeds 3

[0127] (b) Image misalignment evaluation The image misalignment was evaluated by comparing the thickness of thin lines using the same film heating type heat fixing device 40 as used in the evaluation of the change in roughness before and after passing 20,000 sheets of paper. An image (print area ratio 4%) was printed on an A4 sheet of paper with a grid pattern of 3-pixel line width. Theoretically, the line width of 3 pixels is 127 μm. The line width of the image was measured using a microscope VK-8500 (manufactured by Keyence). Five points were randomly selected from the line that was passed through the fixing film so that it was parallel to the longitudinal direction, and the line width was measured. The average value of the three points excluding the minimum and maximum values ​​was taken as d (μm). Then, L below was calculated. L(μm)=d-127

[0128] The L value was evaluated according to the following evaluation criteria to evaluate image quality. The d value increases because the toner melts and spreads in the paper feed direction due to paper slippage during fixing. Therefore, the more paper slippage is suppressed, the smaller the L value becomes. (Evaluation criteria) 3: L is less than 5 μm 2: L is 5 μm or more and less than 15 μm 1: L is 15 μm or more

[0129] <Abrasion resistance evaluation> The abrasion resistance was evaluated using a film heating type heat fixing device 40 shown in Figure 2, which was equipped with the manufactured fixing film. The pressure roller was rotated so that the surface movement speed (circumferential speed) was 320 mm / sec, with a pressure of 156.8 N on one end and a total pressure of 313.6 N (32 kgf). With the surface temperature of the fixing film at the paper passing section controlled at 170°C, 70 sheets of paper of the same size (A4 landscape, GF-C068) were continuously passed through at a rate of 70 sheets / min. A rating of 2 to 4 based on the following evaluation criteria was determined to indicate that the effects of the present disclosure were achieved.

[0130] The smaller the slippage between the fixing film and the recording material in the edge region B, the smaller the scraped portion described below. Also, the better the crystallinity of the edge region 41aB of the surface layer of the fixing film, the smaller the scraped portion described below. (Evaluation criteria) 4: Even after 500,000 sheets have been passed through, there is almost no wear at the edge of the surface layer. 3: Even when passing 200,000 sheets, almost no scratched parts can be seen in the end region of the surface layer. However, when passing 500,000 sheets, slight scratched parts can be seen in the end region of the surface layer due to the paper end. 2: When passing 200,000 sheets, slight scratched parts can be seen in the end region of the surface layer due to the paper end. When passing 500,000 sheets, distinct scratched parts can be seen in the end region of the surface layer due to the paper end. 1: When passing 200,000 sheets, distinct scratched parts can be seen in the end region of the surface layer due to the paper end.

[0131] <Evaluation of Image Glossiness in NN Environment> The evaluation of image glossiness was carried out using a heat fixing device 40 with a film heating method similar to the evaluation of abrasion resistance. Under an environment of temperature 23°C and relative humidity 50% (NN environment), a solid black image was fixed in a state where the surface temperature of the paper passing part of the fixing film was controlled at 160°C. The paper used was A4 size paper (product name: GFC - 081 (81.0 g / m 2 ); sold by Canon Marketing Japan Inc.). The 60° gloss of the output image was measured with a gloss meter (handheld gloss meter PG - 1M manufactured by Nippon Denshoku Industries Co., Ltd.), and its average value was evaluated according to the following criteria. The better the adhesion between the fixing member and the recording material and the more toner there is, the higher the 60° gloss. (Evaluation Criteria) 4: 60° gloss is 10 or more 3: 60° gloss is 8 or more and less than 10 2: 60° gloss is 6 or more and less than 8 1: 60° gloss is less than 6

[0132] <Example 2> In the heat treatment of the surface layer, a fixing film was obtained in the same manner as in Example 1, except that the cooling rate of the heating cylinder was changed to 60°C / min.

[0133] <Example 3> In the inner surface treatment of the PFA tube, a fixing film was obtained in the same manner as in Example 1, except that the number of shots of KrF excimer laser light in the central region was changed to 7 shots.

[0134] <Example 4> A fixing film was obtained in the same manner as in Example 1, except that in the treatment of the inner surface of the PFA tube, the number of shots of the KrF excimer laser light in the central region was changed to 5 shots.

[0135] <Example 5> A fixing film was obtained in the same manner as in Example 1, except that in the treatment of the inner surface of the PFA tube, the number of shots of the KrF excimer laser light in the central region was changed to four shots.

[0136] Example 6 A fixing film was obtained in the same manner as in Example 1, except that in the treatment of the inner surface of the PFA tube, the number of shots of the KrF excimer laser light in the end region was changed to 10 shots.

[0137] Example 7 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 8° C. / min.

[0138] Example 8 A fixing film was obtained in the same manner as in Example 1, except that the thickness of the PFA tube was changed to 30 μm.

[0139] Example 9 A fixing film was obtained in the same manner as in Example 1, except that in the treatment of the inner surface of the PFA tube, the number of shots of KrF excimer laser light was changed to 5 shots in the central region and 7 shots in the end regions.

[0140] Example 10 In the treatment of the inner surface of the PFA tube, the number of shots of KrF excimer laser light in the central region was changed to 5. In addition, in the heat treatment of the surface layer, the cooling rate of the heating cylinder was changed to 60°C / min to obtain a fixed film. A fixing film was obtained in the same manner as in Example 1 except for the above.

[0141] Example 11 A fixing film was obtained in the same manner as in Example 1, except that the thickness of the PFA tube was changed to 40 μm.

[0142] <Comparative Example 1> For the inner surface treatment of the PFA tube, the irradiation conditions were changed so that the entire area was irradiated with 10 shots of KrF excimer laser light. After the surface layer was heat-treated, the fixing film was pressed against a surface transfer member heated to 350°C with a pressure of 50 N while rotating, and surface transfer treatment was performed. A stainless steel member with an arithmetic mean roughness RaA of 0.18 μm in the central region and an arithmetic mean roughness RaB of 0.11 μm in the edge regions was used as the surface transfer member. A fixing film was obtained in the same manner as in Example 1 except for the above.

[0143] <Comparative Example 2> A fixing film was obtained in the same manner as in Example 1, except that in the treatment of the inner surface of the PFA tube, the number of shots of KrF excimer laser light was changed to 8 shots in the central region and 6 shots in the end regions.

[0144] <Comparative Example 3> In the heat treatment of the surface layer, the fixing film was placed in the heating barrel, and after 3 minutes had passed, the fixing film was removed from the heating barrel into a room temperature atmosphere without cooling the heating barrel, and allowed to cool naturally. The fixing film was obtained in the same manner as in Example 1.

[0145] The endothermic heat amounts RaA, RaB, DA, and DB of the surface layer edge regions of the prepared fixing films were determined in Examples 2 to 10 and Comparative Examples 1 to 3. In addition, the abrasion resistance, melting unevenness, and image gloss were evaluated using the same evaluation methods as in Example 1. These results are shown in Table 1.

[0146] [Table 1]

[0147] The disclosure of this embodiment includes the following configuration. (Configuration 1) A fixing member having an endless shape, At least a base layer, an elastic layer, and a surface layer in this order; the surface layer contains crystals of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), When the total width of the fixing member in the longitudinal direction perpendicular to the circumferential direction is defined as L, a region of the fixing member extending from the midpoint of the fixing member in the longitudinal direction toward both ends to a position of 0.35×L is defined as a central region A, and regions of the fixing member extending from both ends of the longitudinal direction toward the midpoint to a position of 0.15×L are defined as end regions B, a surface SA of the central region A and a surface SB of the end region B that constitute the outer surface of the fixing member are each roughened by the crystals, When the arithmetic mean roughness of the surface SA is RaA and the arithmetic mean roughness of the surface SB is RaB, the following formula (1) is satisfied: RaA>RaB (1) A fixing member characterized in that, when a sample taken from the surface layer in the end region B is measured using a differential scanning calorimeter (DSC) at a temperature rise rate of 20°C / min, the amount of heat absorbed during the temperature rise process is 21 J / g or more in an endothermic curve. (Configuration 2) The RaA is 0.15 μm or more and 0.22 μm or less, 2. The fixing member according to claim 1, wherein the RaB is 0.06 μm or more and 0.13 μm or less. (Configuration 3) The area average diameter DA of the PFA spherulites contained in the surface layer in the central region A of the surface layer is 25 μm or more and 40 μm or less, 3. The fixing member according to claim 1, wherein the spherulites in the edge region B of the surface layer have an area-average diameter DB of 5 μm or more and 20 μm or less. (Configuration 4) 4. The fixing member according to any one of configurations 1 to 3, wherein the surface layer has a thickness of 30 μm or less. (Configuration 5) 5. The fixing member according to any one of configurations 1 to 4, wherein the surface SA and the surface SB have different surface roughnesses due to the area mean diameter of the crystals. (Configuration 6) 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 configurations 1 to 5. [Explanation of symbols]

[0148] 10: image forming unit, 11: photosensitive drum, 12: charger, 13: laser scanner, 14: developing unit, 15: cleaner, 17: primary transfer blade, 20: paper feed cassette, 25: multi-paper feed tray, 23: registration roller pair, 31: intermediate transfer belt, 35: secondary transfer roller, 40: heat fixing device, 41: fixing film, 41a: surface layer, 41aA: central region, 41aB: edge region, 41b: base layer, 41c: elastic layer, 43: heater, 44: pressure roller, 45: contact thermometer (thermistor), 46: heater holder, P: recording material, T: unfixed toner

Claims

1. A fixing member having an endless shape, At least a base layer, an elastic layer, and a surface layer in this order; the surface layer contains crystals of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), When the total width of the fixing member in the longitudinal direction perpendicular to the circumferential direction is defined as L, a region of the fixing member extending from the midpoint of the fixing member in the longitudinal direction toward both ends to a position of 0.35×L is defined as a central region A, and regions of the fixing member extending from both ends of the longitudinal direction toward the midpoint to a position of 0.15×L are defined as end regions B, a surface SA of the central region A and a surface SB of the end region B that constitute the outer surface of the fixing member are each roughened by the crystals, When the arithmetic mean roughness of the surface SA is RaA and the arithmetic mean roughness of the surface SB is RaB, the following formula (1) is satisfied: RaA>RaB (1) a fixing member characterized in that, when a sample taken from the surface layer in the edge region B is measured using a differential scanning calorimeter (DSC) at a temperature rise rate of 20°C / min, the amount of heat absorbed during the temperature rise process is 21 J / g or more in an endothermic curve.

2. The RaA is 0.15 μm or more and 0.22 μm or less, 2. The fixing member according to claim 1, wherein the RaB is 0.06 [mu]m or more and 0.13 [mu]m or less.

3. an area average diameter DA of the spherulites of the PFA contained in the surface layer in the central region A of the surface layer is 25 μm or more and 40 μm or less; 2. The fixing member according to claim 1, wherein the spherulites in the edge region B of the surface layer have an area-average diameter DB of 5 [mu]m or more and 20 [mu]m or less.

4. 2. The fixing member according to claim 1, wherein the surface layer has a thickness of 30 [mu]m or less.

5. 2. The fuser member of claim 1, wherein the surface SA and the surface SB have different surface roughnesses due to the area mean diameter of the crystals.

6. 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 5.

Images