Electrophotographic member, fixing device, and electrophotographic image forming apparatus

Abstract

To provide an electrophotographic member with which excellent releasability from toner over a long-term use and good image quality are obtained.SOLUTION: An electrophotographic member has a base layer, an elastic layer on an outer peripheral surface of the base layer, and a surface layer on an outer peripheral surface of the elastic layer. The surface layer includes a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. A plurality of crystals of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer different in equivalent circle diameter are exposed on an outer surface of the surface layer. At least a part of an outer surface of the electrophotographic member is formed of surfaces of the crystals, and is roughened by the crystals. When an arithmetic average height Sa of each of observation areas in a predetermined area of the outer surface is determined, in a frequency distribution of the observation area using the arithmetic average height Sa as a grade and having a grade width of 0.05 μm, a predetermined relation is satisfied.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Fixing members used in fixing devices of electrophotographic image forming devices such as printers, copiers, and facsimiles are available in film or roller shapes. Known fixing members include a film- or roller-shaped substrate made of heat-resistant resin or metal, with an elastic layer or surface layer made of heat-resistant rubber or the like formed thereon as needed. For example, a fluororesin having releasability is used for the surface layer. Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) is a fluororesin having excellent releasability for toner, and is preferably used for the surface layer.

[0003] In recent years, electrophotographic image forming apparatuses have been required to have additional improvements in performance, such as higher print speed, higher image quality, energy saving performance, compatibility with a wide variety of media, etc. For example, when an electrophotographic member is used as a fixing member, technologies for further improving the releasability of the fixing member from toner have been studied in order to accommodate a wide range of fixing conditions. Patent Document 1 discloses a technology for enhancing the non-stickiness of a release layer in a fixing belt having a base layer made of a heat-resistant resin, an elastic layer made of an elastic material disposed on the base layer, and a release layer made of a fluororesin disposed on the elastic layer by forming a specific uneven shape in the release layer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-169530 Summary of the Invention [Problem to be solved by the invention]

[0005] As disclosed in Patent Document 1, forming an uneven shape on the outer surface of a fixing belt can improve the releasability of the surface layer against toner. However, the inventors have found that when such a fixing belt is used as a fixing member, the recording medium becomes slippery during toner fixing, causing the toner to melt and spread in the paper feed direction, which can result in poor image quality, such as thickened fine lines. This is thought to be because the uneven shape on the outer surface of the fixing belt reduces the actual contact area with the recording medium, thereby reducing the coefficient of friction. Furthermore, when mechanical processing methods such as surface transfer or blasting are used to form the uneven shape, the uneven shape may be lost over time due to the heat and pressure during heat fixing, which may reduce the release properties of the toner.

[0006] At least one aspect of the present disclosure is directed to providing an electrophotographic member that provides excellent toner releasability and good image quality over long-term use. At least one aspect of the present disclosure is directed to providing a fixing device that contributes to the stable formation of high-quality electrophotographic images. Furthermore, at least one aspect of the present disclosure is directed to providing an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images. [Means for solving the problem]

[0007] According to at least one aspect of the present disclosure, 1. An electrophotographic member having a base layer, an elastic layer on a peripheral surface of the base layer, and a surface layer on a peripheral surface of the elastic layer, the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer; a plurality of crystals of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having different equivalent circle diameters are exposed on the outer surface of the surface layer; at least a portion of the outer surface of the electrophotographic member is made up of the surface of the crystals and is roughened by the crystals; On the outer surface of the electrophotographic member, a rectangular region having a length of 5 mm in a direction along the circumferential direction of the electrophotographic member and a length of 10 mm in a longitudinal direction perpendicular to the circumferential direction was arranged so that the center of the longitudinal direction of the rectangular region coincided with the center of the longitudinal direction of the electrophotographic member, and the rectangular region was divided into 200 observation regions by squares with sides of 500 μm, and the arithmetic mean height Sa of each of the observation regions was determined. In the frequency distribution of the observation area in which the arithmetic mean height Sa is used as a class and the class width is 0.05 μm, When the number of observation regions included in the observation region group X1 in which the arithmetic mean height Sa belongs to the class of 0.10 to 0.40 μm is defined as x1, x1 satisfies 160≦x1≦200, The number of the observation regions included in the observation region group X2 in which the arithmetic mean height Sa belongs to the class of 0.10 to 0.20 μm is defined as x2, When the number of observation regions included in the observation region group X3 belonging to the class of 0.25 to 0.40 μm in arithmetic mean height Sa is x3, x1 and x2 satisfy the following formula (1), and x1 and x3 satisfy the following formula (2), an electrophotographic member is provided. 0.25 x1≦x2≦0.75 x1 (1) 0.25 x1≦x3≦0.75 x1 (2)

[0008] According to at least one aspect of the present disclosure, A fixing device in an electrophotographic image forming apparatus, The fixing device includes a fixing member and a pressure member disposed opposite the fixing member, A fixing apparatus is provided in which at least one of the fixing member and the pressure member is an electrophotographic member of the present disclosure.

[0009] According to at least one aspect of the present disclosure, An electrophotographic image forming apparatus including a fixing device, The fixing device includes a fixing member and a pressure member disposed opposite the fixing member, An electrophotographic imaging apparatus is provided wherein at least one of the fixing member and the pressure member is an electrophotographic member of the present disclosure. [Effects of the Invention]

[0010] According to at least one aspect of the present disclosure, an electrophotographic member can be obtained that exhibits excellent toner releasability and good image quality over long periods of use. Furthermore, according to at least one aspect of the present disclosure, a fixing device that contributes to the stable formation of high-quality electrophotographic images can be obtained. Furthermore, according to at least one aspect of the present disclosure, an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images can be obtained. [Brief explanation of the drawings]

[0011] [Figure 1] Schematic diagram of an image forming apparatus [Figure 2] Schematic diagram of a fixing device [Figure 3] Schematic diagram of fixing film DETAILED DESCRIPTION OF THE INVENTION

[0012] In this specification, expressions such as "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, unless otherwise specified. Furthermore, when a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined. Furthermore, in this disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ. Hereinafter, embodiments of the present disclosure will be described in detail. However, the technical scope of the present disclosure is not limited to the following description.

[0013] The present disclosure provides: 1. An electrophotographic member having a base layer, an elastic layer on a peripheral surface of the base layer, and a surface layer on a peripheral surface of the elastic layer, the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer; a plurality of crystals of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having different equivalent circle diameters are exposed on the outer surface of the surface layer; at least a portion of the outer surface of the electrophotographic member is made up of the surface of the crystals and is roughened by the crystals; On the outer surface of the electrophotographic member, a rectangular region having a length of 5 mm in a direction along the circumferential direction of the electrophotographic member and a length of 10 mm in a longitudinal direction perpendicular to the circumferential direction was arranged so that the center of the longitudinal direction of the rectangular region coincided with the center of the longitudinal direction of the electrophotographic member, and the rectangular region was divided into 200 observation regions by squares with sides of 500 μm, and the arithmetic mean height Sa of each of the observation regions was determined. In the frequency distribution of the observation area in which the arithmetic mean height Sa is used as a class and the class width is 0.05 μm, When the number of observation regions included in the observation region group X1 in which the arithmetic mean height Sa belongs to the class of 0.10 to 0.40 μm is defined as x1, x1 satisfies 160≦x1≦200, The number of the observation regions included in the observation region group X2 in which the arithmetic mean height Sa belongs to the class of 0.10 to 0.20 μm is defined as x2, When the number of observation regions included in the observation region group X3 belonging to the class of 0.25 to 0.40 μm in arithmetic mean height Sa is x3, x1 and x2 satisfy the following formula (1), and x1 and x3 satisfy the following formula (2). 0.25 x1≦x2≦0.75 x1 (1) 0.25·x1≦x3≦0.75·x1 (2).

[0014] <Electrophotographic materials> An electrophotographic member according to at least one embodiment of the present disclosure is, for example, a fixing member. For example, the electrophotographic member is a fixing belt. The electrophotographic member may also be an endless electrophotographic belt. The electrophotographic member has 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 outer peripheral surface of the base layer, and a surface layer on the outer peripheral surface of the elastic layer. Other layers may be provided between the base layer, the elastic layer, and the surface layer, and on the inner peripheral surface of the base layer and the outer peripheral surface of the surface layer, as needed.

[0015] As shown in FIGS. 2 and 3, the fixing member is, for example, a fixing film 41. The fixing member 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.

[0016] Each layer will be specifically described below. <base layer> The material of the base layer 41b is not particularly limited, and well-known materials can be used. For example, metals and alloys such as aluminum, iron, stainless steel (SUS), and nickel, as well as heat-resistant resins such as polyimide, are used. Stainless steel is preferred. The thickness of the base layer 41b is not particularly limited, but from the viewpoints of strength, flexibility, and heat capacity, it is preferably 20 μm to 100 μm, and more preferably 20 μm to 50 μm.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] <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 allows 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 to 20 μm, and more preferably 10 to 15 μm. The inner sliding layer may be formed using a known coating method or the like.

[0022] <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.

[0023] 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.

[0024] 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.

[0025] The liquid silicone rubber composition typically contains the following components (a) to (d): Component (a): an organopolysiloxane having an unsaturated aliphatic group; Component (b): an organopolysiloxane having silicon-bonded active hydrogen; Component (c): catalyst; Component (d): Thermally conductive filler Each component will be described below.

[0026] 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 (1) and (2). The organopolysiloxane having an unsaturated aliphatic group is preferably a linear type. [ka]

[0027] In formula (1), m 1 indicates an integer of 0 or greater, and n 1 represents an integer of 3 or more. In addition, in the structural formula (1), 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. [ka]

[0028] In formula (2), 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.

[0029] In formulas (1) and (2), R 1 and R 3 Examples 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 (for example, phenyl groups). Substituted hydrocarbon groups Substituted alkyl groups (for example, chloromethyl, 3-chloropropyl, 3,3,3-trifluoropropyl, 3-cyanopropyl, 3-methoxypropyl).

[0030] The organopolysiloxanes represented by formulas (1) and (2) 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 3Preferably, 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.

[0031] In addition, in formulas (1) and (2), 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.

[0032] 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 20c. 2 If 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, rotational viscometer, or the like, in accordance with JIS Z 8803:2011.

[0033] 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 conductivity, based on the liquid silicone rubber composition used to form the elastic layer 20c.

[0034] 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. 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.

[0035] Specific examples of component (b) include the linear organopolysiloxane shown in formula (3) below and the cyclic organopolysiloxane shown in formula (4) below. [ka] In formula (3), 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]

[0036] In formula (4), 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.

[0037] R in formulas (3) and (4) 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.

[0038] Ingredient (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.

[0039] 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. Silicon metal (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, pitch-based carbon fiber.

[0040] <Adhesive layer> The electrophotographic member may have an adhesive layer between the elastic layer 41c and the surface layer 41a. The adhesive layer facilitates adhesion between the elastic layer and the surface layer. The material of the adhesive layer is not particularly limited, and known materials may be used. For example, the adhesive layer preferably contains a cured adhesive. The adhesive may be a solution-type adhesive or a hot-melt-type adhesive. The adhesive is not particularly limited, and any known adhesive can be used, but it is preferable to use a silicone rubber adhesive. The thickness of the adhesive layer is not particularly limited, but is preferably 1 to 20 μm, and more preferably 3 to 10 μm.

[0041] <Surface layer> The surface layer 41a is made of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. The surface layer 41a preferably comprises PFA. 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 liquid (water-based dispersion paint) or powder paint containing PFA as a 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 coated on the surface of the elastic layer 41c. The surface layer 41a can be, for example, a PFA tube.

[0042] 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.).

[0043] 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. 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 bending (locking)). Also, there is a characteristic of PFA, 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 -1In the case of the perfluoromethoxy group, it appears at 881 cm -1 Appears in.

[0044] A rectangular region measuring 5 mm in the circumferential direction of the electrophotographic member and 10 mm in the longitudinal direction perpendicular to the circumferential direction is arranged on the outer surface of the electrophotographic member so that the longitudinal center of the rectangular region coincides with the longitudinal center of the electrophotographic member. The rectangular region is divided into 200 observation regions by squares with sides of 500 μm. The arithmetic mean height Sa of each observation region is calculated. In a frequency distribution of the observation regions, where the arithmetic mean height Sa is the class and the class width is 0.05 μm, the number of observation regions included in an observation region group X1 that belong to the class with the arithmetic mean height Sa of 0.10 to 0.40 μm is defined as x1, where x1 satisfies 160≦x1≦200. Furthermore, when the number of observation regions included in an observation region group X2 that belong to the class with the arithmetic mean height Sa of 0.10 to 0.20 μm in the frequency distribution of the observation regions is defined as x2, x1 and x2 satisfy the following formula (1): Furthermore, when the number of observation regions included in the observation region group X3 that belongs to the class of 0.25 to 0.40 μm in the frequency distribution of the observation regions is denoted by x3, x1 and x3 satisfy the following formula (2). Here, in formulas (1) and (2), an expression such as 0.25·x1 means multiplying 0.25 by x1. The same applies to formulas (3) to (6) below. 0.25 x1≦x2≦0.75 x1 (1) 0.25 x1≦x3≦0.75 x1 (2)

[0045] In a rectangular region of the electrophotographic member having a length of 5 mm along the circumferential direction and a length of 10 mm in the longitudinal direction perpendicular to the circumferential direction, when x1, x2, and x3 are 160≦x1≦200 and satisfy the above formulas (1) and (2), there is a sufficient region where Sa is 0.10 to 0.40 μm, and regions with different arithmetic mean heights Sa exist in a similar proportion within the nip during fixing. This improves toner releasability, suppresses slippage of the recording medium, and achieves good image quality.

[0046] Specifically, in the region where Sa is less than 0.10 μm, the surface irregularities become too small, The releasability of the toner tends to decrease. Also, in the region where Sa exceeds 0.40 μm, the actual contact area with the recording medium becomes too small, making it difficult to prevent the recording medium from slipping. Furthermore, in the region where Sa is 0.20 μm or less, the actual contact area with the recording medium is large, resulting in a high coefficient of friction. Therefore, if there are many regions where Sa is 0.20 μm or less, the slippage of the recording medium tends to be suppressed well. On the other hand, in the region where Sa is 0.25 μm or more, the surface irregularities are large. Therefore, if there are many regions where Sa is 0.25 μm or more, the release properties for toner tend to be good.

[0047] That is, satisfying the above formula (1) indicates that the number of observation regions included in the observation region group X2, which belongs to the class of arithmetic mean height Sa of 0.10 to 0.20 μm, is sufficient relative to the number of observation regions included in the observation region group X1, which belongs to the class of 0.10 to 0.40 μm. Furthermore, satisfying the above formula (2) indicates that the number of observation regions included in the observation region group X3, which belongs to the class of 0.25 to 0.40 μm, is sufficient relative to the number of observation regions included in the observation region group X1, which belongs to the class of 0.10 to 0.40 μm. Therefore, satisfying both the above formulas (1) and (2) makes it possible to achieve both excellent toner releasability and good image quality.

[0048] Furthermore, in order to facilitate a satisfactory effect in improving releasability as described above, it is preferable that the number y1 of observation regions included in the observation region group Y1 belonging to the class where Sa is less than 0.10 μm be less than 40. In order to facilitate a satisfactory effect in suppressing slippage of the recording medium, it is preferable that the number y2 of observation regions included in the observation region group Y2 belonging to the class where Sa is greater than 0.40 μm be less than 40.

[0049] x1 preferably satisfies 180≦x1≦200. When x1 is in the above range, there is a larger region where Sa is 0.10 to 0.40 μm, which makes it easier to improve the releasability of the toner, suppress slippage of the recording medium, and make it easier to obtain good image quality. x2 preferably satisfies 40≦x2≦165, more preferably 50≦x2≦150, even more preferably 60≦x2≦140, and particularly preferably 70≦x2≦100. When x2 is within the above range, the above formula (1), the following formula (3), or the following formula (5) is more likely to be satisfied. x3 preferably satisfies 40≦x3≦165, more preferably 50≦x3≦150, even more preferably 60≦x3≦140, and particularly preferably 70≦x3≦100. When x3 is within the above range, the above formula (2), the following formula (4), or the following formula (6) is more likely to be satisfied. The methods for adjusting and measuring x1, x2, and x3 will be described later.

[0050] It is more preferable that x1 and x2 satisfy the following formula (3), and x1 and x3 satisfy the following formula (4). 0.30·x1≦x2≦0.70·x1 (3) 0.30·x1≦x3≦0.70·x1 (4) When x1, x2, and x3 satisfy the above formulas (3) and (4), the toner releasability and the suppression of slippage of the recording medium are improved. Furthermore, it is more preferable that x1 and x2 satisfy the following formula (5), and that x1 and x3 satisfy the following formula (6). 0.35·x1≦x2≦0.65·x1 (5) 0.35·x1≦x3≦0.65·x1 (6)

[0051] Furthermore, a plurality of PFA crystals with different equivalent circle diameters are exposed on the outer surface of the surface layer. The fact that the plurality of crystals have different equivalent circle diameters is confirmed by the method described below. At least a part of the outer surface of the electrophotographic member is made up of the surface of the crystals and is roughened by the crystals. This prevents the outer surface of the electrophotographic member from becoming rough over a long period of use. The PFA crystals can be formed in a flattened state, have good releasability for toner, and suppress slippage of the recording medium, thereby achieving good image quality. The crystal shape of the PFA is not particularly limited, but may be, for example, a spherulite.

[0052] The crystal-roughened surface is, for example, a state in which PFA crystals are formed on the outer surface, and an uneven shape is formed along the crystal shape. Here, the larger the crystal diameter, the larger the uneven shape. The uneven shape formed along the crystal shape is difficult to flatten due to the heat and pressure during fixing, and the uneven shape can be maintained over long periods of use. The method of roughening the surface with crystals will be described later.

[0053] The method for confirming that at least a part of the outer surface of the electrophotographic member is roughened with PFA crystals is as follows. Two observation regions are extracted from each of the observation region groups X2 and X3, for a total of four. The arithmetic mean height Sa and the area mean diameter of the crystals are calculated for each observation region using the method described below. The correlation coefficient R between Sa and the area mean diameter of each of the four observation regions is determined, and if R is +0.90 or greater, the surface is determined to be roughened by crystals. That is, the correlation coefficient R is +0.90 or greater, preferably +0.95 or greater, and more preferably +0.98 or greater. There is no particular upper limit, and preferred values include +0.90 to +1.00, +0.95 to +1.00, and +0.98 to +1.00. The correlation coefficient R can be adjusted by controlling the area mean diameter of the PFA crystals on the outer surface of the electrophotographic member.

[0054] A method for exposing a plurality of PFA crystals having different equivalent circle diameters on the outer surface of the surface layer and constituting at least a part of the outer surface of the electrophotographic member with a PFA crystal surface can be exemplified by a method in which, after forming the surface layer 41a in the manufacturing process of the electrophotographic member, the PFA is crystallized by heating the surface layer 41a to a temperature equal to or higher than the melting point of PFA and then cooling the surface layer 41a to form crystals. Although the specific method is not particularly limited, the following methods for heat treatment of the surface layer can be used.

[0055] 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 electrophotographic member. The heating temperature is preferably from the melting point of PFA to 350°C or lower. The heating time may be any time long enough to allow the surface layer to reach the desired temperature, and examples of the heating time include 1 to 20 minutes, 1 to 10 minutes, and 2 to 5 minutes.

[0056] After heating is completed, the cooling rate of the electrophotographic member is controlled by controlling the cooling rate of the heating barrel. 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 crystallization temperature range of PFA, the smaller the PFA crystal diameter. The cooling rate is preferably controlled until the temperature of the surface layer falls below the crystallization temperature range of PFA. The cooling rate may be within a range that allows the PFA crystal diameter to be controlled to the desired size, and is, for example, preferably 10 to 60°C / min, more preferably 25 to 60°C / min, even more preferably 35 to 60°C / min, and particularly preferably 45 to 60°C / min.

[0057] One method for setting x1, x2, and x3 within the above ranges is to control the area-average diameter of PFA crystals on the outer surface of the electrophotographic member. Increasing the area-average diameter of PFA crystals increases the arithmetic mean height Sa. Conversely, decreasing the area-average diameter of PFA crystals decreases the arithmetic mean height Sa. The following describes a method for controlling the area-average diameter of PFA crystals. The area average diameter of PFA crystals is determined by increasing the frequency of crystal nuclei relative to the PFA crystal growth rate. It is believed that the area average diameter of the crystals on the outer surface becomes smaller as the temperature increases. For example, to reduce the area average diameter of the crystals on the outer surface, one method is to increase the cooling rate in the crystallization temperature range of PFA, as mentioned above. Another method is to place a substance that acts as a nucleating agent for crystals on the inner side of the surface layer 41a, i.e., near the surface facing the elastic layer. This increases the frequency of crystal nuclei on the inner side. Since crystals grow from crystal nuclei and stop growing when they come into contact with other crystals, a high frequency of crystal nuclei results in a smaller crystal diameter on the inner surface side. In the surface layer 41a, the smaller the crystal diameter on the inner surface side, the smaller the area-average diameter of the crystals on the outer surface. This is thought to be because crystals first form on the inner surface side, and then molecules adhere to the surface, causing crystallization to progress toward the outer surface. Therefore, a high frequency of crystal nuclei on the inner surface side tends to result in a smaller area-average diameter of the crystals on the outer surface. Conversely, a low frequency of crystal nuclei on the inner surface side tends to result in a larger area-average diameter of the crystals on the outer surface.

[0058] To create a crystal 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.

[0059] When an electrophotographic member is manufactured by a conventional method, the area-average diameter of the crystals is uniform in each of the 200 observation regions divided into squares with sides of 500 μm, and the frequency distribution of Sa is narrow.

[0060] As a specific method for setting x1, x2, and x3 within the above ranges, the following method can be used. Here, an example is given in which a PFA tube is used to produce the surface layer 41a, but the surface layer according to the present disclosure is not limited to one formed using a PFA tube.

[0061] 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 crystals on the surface of the surface layer. In this process, it is preferable to control the crystal diameter by controlling the cooling rate within the crystallization temperature range of the PFA.

[0062] 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.

[0063] 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.

[0064] In excimer laser treatment, fluorine atoms on the surface of the inner side of the PFA tube are released, causing reactions such as carbonization and the generation of carbonyl groups through reactions with oxygen. The element ratio on the surface of the material changes. The carbon generated by this process acts as a nucleating agent, so this method allows the nucleating agent to exist on the inner surface.

[0065] Here, it is preferable to control the amount of carbon on the surface of the surface layer facing the elastic layer by controlling the irradiation conditions of the excimer laser light and controlling the carbonization of the inner surface of the PFA tube. The irradiation conditions of the excimer laser light are usually selected from the viewpoint of improving wettability and adhesion, and the irradiation amount per shot or the number of shots is adjusted. In the present disclosure, it is preferable to adjust the overlapping of the excimer laser light to create areas with a high number of shots and areas with a low number of shots, and to control the amount of carbon on the inner surface of the PFA tube for each area. In a rectangular region on the inner surface of the PFA tube, the area ratio of the region with a high number of shots is preferably controlled to 35% to 65%, more preferably 40% to 60%, in a circumferential direction of 5 mm and a longitudinal direction perpendicular to the circumferential direction of 10 mm. In addition, in the rectangular region, the area ratio of the region with a low number of shots is preferably controlled to 35% to 65%, more preferably 40% to 60%.

[0066] In the region where the number of shots is large, the amount of carbon on the inner surface of the PFA tube increases, which makes it easier to reduce the area-average diameter of PFA crystals 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 region where the number of shots is small, the amount of carbon on the inner surface of the PFA tube decreases, which makes it easier to increase the area-average diameter of PFA spherulites on the outer surface of the surface layer. The number of shots in this case is preferably 2 to 5, more preferably 2 to 4. In addition, the dose of excimer laser light is preferably 100 to 600 mJ / cm. 2 / pulse, preferably 200-400mJ / cm 2 / pulse.

[0067] 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.

[0068] The area-average diameter z2 of the crystals in at least one of the observation regions included in the observation region group X2 is preferably 10.0 to 25.0 μm, and more preferably 11.0 to 20.0 μm. Within this range, it becomes easier to set x2 within the above range. z2 can be adjusted by the method for adjusting the area-average diameter of PFA crystals described above. The method for measuring z2 will be described later.

[0069] The area-average diameter z3 of the crystals in at least one of the observation regions included in the observation region group X3 is preferably 35.0 to 60.0 μm, and more preferably 40.0 to 50.0 μm. Within this range, it becomes easier to set x3 within the above range. z3 can be adjusted by the above-mentioned method for adjusting the area-average diameter of the PFA crystals. The method for measuring z3 will be described later.

[0070] Furthermore, when the arithmetic mean thickness of the surface layer of 200 observation areas is determined, the difference Δt between the maximum and minimum arithmetic mean thicknesses is preferably 2.00 μm or less, more preferably 1.20 μm or less. By being in the above range, contact between each observation area and the recording medium is improved, resulting in better toner releasability and better suppression of recording medium slippage. The lower limit of Δt is not particularly limited, but preferred examples include 0.00 to 2.00 μm, 0.00 to 1.20 μm, and 0.40 to 1.20 μm. Δt can be adjusted by changing the thickness of the surface layer or by changing the cooling rate during heat treatment of the surface layer. The method for measuring Δt will be described later.

[0071] The thickness of the surface layer 41a is preferably 10 to 30 μm. If the thickness is 30 μm or less, the influence of the nucleating agent on the inner surface side of the surface layer on Sa becomes greater, making it easier to make the PFA crystals smaller, and therefore, it is possible to better suppress slippage of the recording medium. If the thickness is 10 μm or more, it is easier to make the PFA crystals larger, making it possible to better improve the releasability of the toner. The thickness of the surface layer is more preferably 15 to 30 μm. The thickness of the surface layer can be adjusted by changing the thickness of the PFA tube. A method for measuring the thickness of the surface layer will be described later.

[0072] <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."

[0073] 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, forming an electrostatic latent image. The electrostatic 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 belt 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.

[0074] Meanwhile, recording material P is fed one sheet at a time from paper feed cassette 20 or multi-paper feed tray 25 in the direction of arrow 3 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 belt 31 and sends recording material P between intermediate transfer belt 31 and secondary transfer roller 35. The color toner image on the intermediate transfer belt 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 the recording material P by heating and pressing recording material P by fixing device 40.

[0075] The electrophotographic image forming apparatus includes a fixing device 40. Next, the fixing device in the electrophotographic image forming apparatus will be described. The fixing device includes a fixing member and a pressure member disposed opposite the fixing member. FIG. 2 is a schematic diagram of the fixing device 40, and is an example of a film heating type heating device (tensionless type). This type of heating device is used in this example, but a roller pair type or film type heating device can also be used.

[0076] 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.

[0077] An electrophotographic member according to at least one embodiment of the present disclosure can be used as, for example, a fixing member. The fixing member is, for example, a fixing film. 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) including 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 including at least a surface layer 41a, an elastic layer 41c, and a base layer 41b.

[0078] The pressure roller 44 is a heat-resistant elastic pressure roller serving as a pressure member, and includes a core 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 are supported by bearings for free rotation. The electrophotographic member according to at least one embodiment of the present disclosure can also be used as a pressure member. It is preferable that at least one of the fixing member and the pressure member is the electrophotographic member. For example, the pressure member can have a configuration similar to that of the fixing film 41, and the pressure member can have a three-layer composite structure including a surface layer 41a, an elastic layer 41c, and a base layer 41b.

[0079] 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.

[0080] 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 cylindrical fixing film 41.

[0081] The pressure roller 44 is driven to rotate, causing the cylindrical fixing film 41 to rotate in a driven state, 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, a recording material P bearing an unfixed toner image T is introduced between the fixing film 41 and the pressure roller 44 in the fixing nip portion. Then, in the fixing nip portion, the toner image-bearing 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 transported together with the fixing film 41 to the fixing nip portion. During this sandwiching and transport 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 pressurized onto the recording material P, melting and fixing it. After passing through the fixing nip portion, the recording material P separates from the surface of the fixing film 41 and is then discharged and transported.

[0082] Reference numeral 45 denotes a contact thermometer (thermistor) that measures the temperature of the fixing film 41 heated by the heater 43 and passes the detection result to a temperature control means (not shown). Reference numeral 46 denotes a heater holder, which is a member that holds the heater 43 that has been heated to a high temperature.

[0083] The methods for measuring each physical property in the present disclosure are shown below. <Measuring method for arithmetic mean height Sa> A rectangular area measuring 5 mm in the circumferential direction of the electrophotographic member and 10 mm in the longitudinal direction perpendicular to the circumferential direction is placed on the outer surface of the electrophotographic member so that the longitudinal center of the rectangular area coincides with the longitudinal center of the electrophotographic member. The rectangular area is measured using a shape analysis laser microscope (product name: VK-X150, manufactured by Keyence Corporation). Using the shape measurement mode and a 20x objective lens, a shape measurement image of the outermost surface of the surface layer is obtained. The obtained images are then joined to obtain an image of the entire rectangular area. First, surface shape correction is performed on the image of the entire range within the obtained rectangular area using the attached analysis software. Quadratic curve correction is selected as the surface shape correction method. The image is divided into 200 observation areas using squares with sides of 500 μm, and the arithmetic mean height Sa of each observation area is calculated using an S filter of 8 μm and an L filter of 0.25 mm. The arithmetic mean height Sa thus obtained is used as a class, and a frequency distribution of the observation area with a class width of 0.05 μm is created. From this frequency distribution, the arithmetic mean height Sa is classified into a class of 0.10 to 0.40 μm. An observation region group X1 having an arithmetic mean height Sa of 0.10 to 0.20 μm, an observation region group X2 having an arithmetic mean height Sa of 0.25 to 0.40 μm, and an observation region group X3 having an arithmetic mean height Sa of 0.25 to 0.40 μm are obtained, and the values of x1, x2, and x3 are calculated.

[0084] <Method for measuring the area-average diameter of crystals> First, the surface layer of the observation area is isolated. 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 using a microscope (product name: ECLIPSE LV100NDA, manufactured by Nikon Corporation) to obtain an image of the crystals throughout the observation area. The observation conditions are as follows: switched to transmitted illumination, the analyzer and transmitted illumination polarizer are orthogonalized and adjusted to a crossed Nicol configuration, and a 20x objective lens is used. Using a transmitted polarizing microscope, it is possible to obtain an image that allows the crystal structure to be confirmed. Next, the outlines of the crystals within the entire observation area are manually extracted from the obtained observation image. The extraction is performed by extracting the boundary lines of each Maltese cross in the observation image as the crystal outline, since each individual crystal has a cross-shaped shadow known as a Maltese cross. The area of each crystal is calculated using the image analysis software "ImageJ." The area-average diameter of the crystals within the observation area is calculated from the area of each crystal and the equivalent circle diameter calculated from each area. The equivalent circle diameter calculated here confirms the presence of multiple crystals with different equivalent circle diameters. Furthermore, by performing the above operation on the observation regions included in the observation region group X2, the area-average diameter z2 of the crystals in the observation regions included in X2 is calculated. Similarly, the above operation is performed on the observation regions included in the observation region group X3 to calculate the area-average diameter z3 of the crystals in the observation regions included in X3.

[0085] <Method for measuring the difference Δt between the maximum and minimum arithmetic mean thickness of the surface layer in all observation areas> In the same manner as for measuring the arithmetic mean height Sa, the rectangular area is measured using a shape analysis laser microscope (product name: VK-X150, manufactured by Keyence Corporation). Using the shape measurement mode and a 20x objective lens, a measurement image of the thickness of the transparent body is obtained. The obtained images are then linked to obtain an image of the entire range within the rectangular area. First, surface shape correction is performed on the images of the entire range within the obtained rectangular area using the attached analysis software. Quadratic curve correction is selected as the method of surface shape correction. The area is divided into 200 observation areas using squares with sides of 500 μm, and the arithmetic mean thickness of each observation area is calculated. The obtained arithmetic mean thickness is used as the arithmetic mean thickness of the surface layer, and the difference Δt between the maximum and minimum arithmetic mean thicknesses is calculated from the 200 arithmetic mean thicknesses.

[0086] <Method for measuring the thickness of the surface layer> First, in the same manner as in the measurement of the area-average diameter of the crystals, the surface layer is isolated from the electrophotographic member, and the thickness of an arbitrary portion of the isolated surface layer is measured using a micrometer (product name: High-Precision Digimatic Micrometer MDH-25MB, manufactured by Mitutoyo Corporation). [Example]

[0087] 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.

[0088] Example 1 In this example, a fixing film as shown in FIG. 3 was prepared.

[0089] (Inner surface treatment of PFA tube) Neoflon PFA: AP-231SH (manufactured by Daikin Industries, Ltd.) is used as the raw material. A 20 μm thick PFA tube obtained by extrusion molding was used. An aqueous solution containing 5 mass % sodium benzoate and 1 mass % Surflon S-113 (a fluorochemical surfactant manufactured by AGC Seimi Chemical Co., Ltd.) was applied to the entire inner surface of the PFA tube and allowed to dry naturally. After that, a 250 mJ / cm 2 The PFA tube was irradiated with 8 shots of KrF excimer laser light at 1 / 1000 pulses. The irradiation conditions were adjusted so that within a 5 mm circumferential and 10 mm longitudinal area of the inner surface of the PFA tube, the area irradiated with 8 shots and the area irradiated with 4 shots were present in a 50:50 area ratio. In this way, an inner surface-treated PFA tube was obtained.

[0090] (base layer) The base layer was made of SUS with an inner diameter of 24 mm and a thickness of 30 μm.

[0091] (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.

[0092] (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.

[0093] (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

[0094] 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. 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 (Thinky Corporation, ARV-5000) and stirred and mixed at 600 rpm for 2 minutes to obtain mixture 1.

[0095] 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. 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. 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 (hereinafter referred to as "SiH") was weighed. The mixture was added to Substance 3 and mixed thoroughly to obtain a liquid addition-curable silicone rubber composition.

[0096] (Applying adhesive layer) After forming the elastic layer, an adhesive (SE1819CV) was applied to the elastic layer using the ring coating method. A / B (a mixture of equal amounts of "liquid A" and "liquid B" manufactured by Dow-Toray) was applied to a thickness of 7 μm.

[0097] (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 with 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).

[0098] (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.

[0099] 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 substantial 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 60°C / min. Thereafter, the fixing film was taken out of the heating barrel into an atmosphere at room temperature (25°C) to obtain a fixing film. The values of x1, x2, x3, and Δt for the prepared fixing film were determined using the method described above. The area-average crystal diameter was also determined for one of the observation regions included in X2 and X3. Two observation regions were extracted from each of X2 and X3, for a total of four. Sa and the area-average crystal diameter were calculated for each observation region, and the correlation coefficient R between Sa and the area-average crystal diameter for each observation region was calculated. These results are shown in Table 1.

[0100] <Evaluation of toner release after passing 20,000 sheets> The toner releasability after passing 20,000 sheets was evaluated by the following evaluation of hot offset resistance using the film heating type fixing device 40 shown in FIG. 2 incorporating the prepared fixing film. First, with the pressure applied to one end being 156.8 N and the total pressure being 313.6 N (32 kgf), the pressure roller was rotated so that the surface movement speed (circumferential speed) was 300 mm / sec, and 20,000 sheets of paper (A4 landscape, GF-C068) were passed through continuously with the surface temperature of the paper passing section of the fixing film controlled at 170°C.

[0101] Thereafter, the hot offset resistance was evaluated under the following conditions. Evaluation paper: CS-064 (64.0 g / m 2 ) (Sold by Canon Marketing Japan Inc.) Toner amount on evaluation paper: 0.08 mg / cm 2 (Adjusted by DC voltage VDC of the developer carrier, charging voltage VD of the electrostatic latent image carrier, and laser power) Evaluation image: A 2cm x 20cm image placed on the long edge of the A4 paper with a 2mm margin from the leading edge of the paper. Test environment: Normal temperature and low humidity: Temperature 23°C / Humidity 5% RH (hereinafter referred to as "N / L") Pressure: 300N Process speed: 300mm / sec Fixing temperature: 210℃

[0102] The above evaluation image is output and the reflectometer (REFLECTOMETER MODEL The average reflectance Dr (%) of the evaluation paper before image output and the reflectance Ds (%) of the white background after the fixing test were measured using a tester (TC-6DS, manufactured by Tokyo Denshoku Co., Ltd.), and fogging was calculated using the following formula. The obtained fogging was evaluated according to the following evaluation criteria to evaluate hot offset resistance. A good evaluation of hot offset resistance indicates good toner release properties after passing 20,000 sheets. Fog (%) = Dr (%) - Ds (%)

[0103] (Evaluation criteria) A: Less than 0.2% B: 0.2% or more, less than 0.5% C: 0.5% or more, less than 1.0% D: 1.0% or more

[0104] <Image quality evaluation> The image quality was evaluated by comparing the thickness of thin lines using the same film heating type fixing device 40 as used in the evaluation of toner releasability. 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). L was then calculated using the following formula. L(μm)=d-127

[0105] 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) A: Less than 5 μm B: 5 μm or more and less than 10 μm C: 10 μm or more and less than 20 μm D:20μm or more

[0106] <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 40° C. / min.

[0107] Example 3 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 30° C. / min.

[0108] Example 4 In the treatment of the inner surface of the PFA tube, the irradiation conditions were changed so that within a range of 5 mm in the circumferential direction and 10 mm in the longitudinal direction of the PFA tube, there were areas irradiated with 8 shots of KrF excimer laser light and areas irradiated with 4 shots, with an area ratio of 75:25. Then, when cutting both ends to the desired length (336.5 mm), the following conditions were used. The cutting positions on both ends were adjusted to meet this requirement. A rectangular region having a length of 5 mm along the circumferential direction of the fixing film and a length of 10 mm in the longitudinal direction perpendicular to the circumferential direction was arranged so that the center of the longitudinal direction of the rectangular region coincided with the center of the longitudinal direction of the electrophotographic member, and the rectangular region was divided into 200 observation regions by squares with sides of 500 μm.The cutting positions at both ends were adjusted so that the boundaries between the region irradiated with 8 shots of KrF excimer laser light and the region irradiated with 4 shots in the inner surface treatment of the PFA tube coincided with the boundary lines of the observation regions. A fixing film was obtained in the same manner as in Example 1 except for the above.

[0109] <Example 5> A fixing film was obtained in the same manner as in Example 4, except that in the treatment of the inner surface of the PFA tube, the irradiation conditions were changed so that within an area of 5 mm in the circumferential direction and 10 mm in the longitudinal direction of the inner surface of the PFA tube, there were areas irradiated with 8 shots of KrF excimer laser light and areas irradiated with 4 shots, respectively, in an area ratio of 25:75.

[0110] Example 6 A fixing film was obtained in the same manner as in Example 4, except that in the treatment of the inner surface of the PFA tube, the irradiation conditions were changed so that within an area of 5 mm in the circumferential direction and 10 mm in the longitudinal direction of the inner surface of the PFA tube, there were areas irradiated with 8 shots of KrF excimer laser light and areas irradiated with 4 shots, respectively, in an area ratio of 70:30.

[0111] Example 7 A fixing film was obtained in the same manner as in Example 4, except that in the treatment of the inner surface of the PFA tube, the irradiation conditions were changed so that within an area of 5 mm in the circumferential direction and 10 mm in the longitudinal direction of the inner surface of the PFA tube, there were areas irradiated with 8 shots of KrF excimer laser light and areas irradiated with 4 shots, respectively, in an area ratio of 30:70.

[0112] 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 10 μm.

[0113] Example 9 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.

[0114] Example 10 A fixing film was obtained in the same manner as in Example 1, except that the thickness of the PFA tube was changed to 8 μm.

[0115] 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.

[0116] <Comparative Example 1> In the treatment of the inner surface 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 heat treatment of the surface layer, 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. As the surface transfer member, a stainless steel member was used, in which, within a range of 5 mm in the circumferential direction and 10 mm in the longitudinal direction on the outer surface of the surface layer, there existed a region with an arithmetic mean height Sa of 0.15 μm and a region with an arithmetic mean height Sa of 0.35 μm, with an area ratio of 50:50. Ta. A fixing film was obtained in the same manner as in Example 1 except for the above.

[0117] <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 irradiation conditions were changed so that the entire area was irradiated with two shots of KrF excimer laser light.

[0118] <Comparative Example 3> In the treatment of the inner surface of the PFA tube, the irradiation conditions were changed so that the area ratio of the area irradiated with 10 shots of KrF excimer laser light to the area irradiated with 5 shots of KrF excimer laser light was 50:50, and in the heat treatment of the surface layer, the cooling rate of the heating barrel was changed to 20°C / min. A fixing film was obtained in the same manner as in Example 1, except that

[0119] <Comparative Example 4> 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 5° C. / min.

[0120] <Comparative Example 5> A fixing film was obtained in the same manner as in Example 4, except that in the treatment of the inner surface of the PFA tube, the irradiation conditions were changed so that within an area of 5 mm in the circumferential direction and 10 mm in the longitudinal direction of the inner surface of the PFA tube, there were areas irradiated with 8 shots of KrF excimer laser light and areas irradiated with 4 shots, respectively, in an area ratio of 80:20.

[0121] <Comparative Example 6> A fixing film was obtained in the same manner as in Example 4, except that in the treatment of the inner surface of the PFA tube, the irradiation conditions were changed so that within a range of 5 mm in the circumferential direction and 10 mm in the longitudinal direction of the inner surface of the PFA tube, there were areas irradiated with 8 shots of KrF excimer laser light and areas irradiated with 4 shots, respectively, in an area ratio of 20:80.

[0122] Table 1 shows the physical properties and evaluation results of the fixing films according to Examples 2 to 11 and Comparative Examples 1 to 6. In Example 2, the number y2 of observation areas included in the observation area group Y2 belonging to the class where Sa is greater than 0.40 μm was 19. In Example 3, the number y2 of observation areas included in the observation area group Y2 belonging to the class where Sa is greater than 0.40 μm was 40. In Comparative Example 3, the number y1 of observation areas included in the observation area group Y1 belonging to the class where Sa is less than 0.10 μm was 48. In Comparative Example 4, the number y2 of observation areas included in the observation area group Y2 belonging to the class where Sa is greater than 0.40 μm was 47. [Table 1] In the table, x1 indicates the number of observation regions included in observation region group X1, x2 indicates the number of observation regions included in observation region group X2, x3 indicates the number of observation regions included in observation region group X3, z2 indicates the area average diameter (μm) of crystals in at least one of the observation regions included in observation region group X2, z3 indicates the area average diameter (μm) of crystals in at least one of the observation regions included in observation region group X3, and Δt indicates the difference between the maximum arithmetic average thickness and the minimum arithmetic average thickness when the arithmetic average thickness of the surface layer of 200 observation regions is calculated.

[0123] The present disclosure includes the following configurations. (Configuration 1) 1. An electrophotographic member having a base layer, an elastic layer on a peripheral surface of the base layer, and a surface layer on a peripheral surface of the elastic layer, the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer; a plurality of crystals of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having different equivalent circle diameters are exposed on the outer surface of the surface layer; at least a portion of the outer surface of the electrophotographic member is made up of the surface of the crystals and is roughened by the crystals; On the outer surface of the electrophotographic member, a rectangular region having a length of 5 mm in a direction along the circumferential direction of the electrophotographic member and a length of 10 mm in a longitudinal direction perpendicular to the circumferential direction was arranged so that the center of the longitudinal direction of the rectangular region coincided with the center of the longitudinal direction of the electrophotographic member, and the rectangular region was divided into 200 observation regions by squares with sides of 500 μm, and the arithmetic mean height Sa of each of the observation regions was determined. In the frequency distribution of the observation area in which the arithmetic mean height Sa is used as a class and the class width is 0.05 μm, When the number of observation regions included in the observation region group X1 in which the arithmetic mean height Sa belongs to the class of 0.10 to 0.40 μm is defined as x1, x1 satisfies 160≦x1≦200, The arithmetic mean height Sa is included in the observation region group X2 that belongs to the class of 0.10 to 0.20 μm. The number of observation regions is x2, When the number of the observation regions included in the observation region group X3 belonging to the class of the arithmetic mean height Sa of 0.25 to 0.40 μm is defined as x3, x1 and x2 satisfy the following formula (1), and x1 and x3 satisfy the following formula (2): 0.25 x1≦x2≦0.75 x1 (1) 0.25·x1≦x3≦0.75·x1 (2). (Configuration 2) The electrophotographic member according to Configuration 1, wherein x1 and x2 satisfy the following formula (3), and x1 and x3 satisfy the following formula (4): 0.30·x1≦x2≦0.70·x1 (3) 0.30·x1≦x3≦0.70·x1 (4). (Configuration 3) 3. The electrophotographic member according to configuration 1 or 2, wherein the area-average diameter z2 of the crystals in at least one of the observation regions included in the observation region group X2 is 10.0 to 25.0 μm. (Configuration 4) 4. The electrophotographic member according to any one of configurations 1 to 3, wherein the area-average diameter z3 of the crystals in at least one of the observation regions included in the observation region group X3 is 35.0 to 60.0 μm. (Configuration 5) 5. The electrophotographic member according to any one of Configurations 1 to 4, wherein, when the arithmetic mean thickness of the surface layer in the 200 observation regions is determined, the difference Δt between the maximum value of the arithmetic mean thickness and the minimum value of the arithmetic mean thickness is 2.00 μm or less. (Configuration 6) 6. The electrophotographic member according to any one of configurations 1 to 5, wherein the surface layer has a thickness of 10 to 30 μm. (Configuration 7) 7. The electrophotographic member according to any one of Configurations 1 to 6, wherein the electrophotographic member is an electrophotographic belt having an endless shape. (Configuration 8) 8. The electrophotographic member according to configuration 7, wherein the electrophotographic member is a fuser belt. (Configuration 9) A fixing device in an electrophotographic image forming apparatus, The fixing device includes a fixing member and a pressure member disposed opposite the fixing member, 9. A fixing device, wherein at least one of the fixing member and the pressure member is the electrophotographic member according to any one of Configurations 1 to 8. (Configuration 10) An electrophotographic image forming apparatus including a fixing device, The fixing device includes a fixing member and a pressure member disposed opposite the fixing member, 9. An electrophotographic image forming apparatus, wherein at least one of the fixing member and the pressure member is the electrophotographic member according to any one of Configurations 1 to 8. [Explanation of symbols]

[0124] 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: fixing device, 41: fixing film, 41a: surface layer, 41b: base layer, 41c: elastic layer, 43: heater, 44: pressure roller, 45: contact thermistor, 46: heater holder, P: recording material, T: toner

Claims

1. 1. An electrophotographic member having a base layer, an elastic layer on a peripheral surface of the base layer, and a surface layer on a peripheral surface of the elastic layer, the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer; a plurality of crystals of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having different equivalent circle diameters are exposed on the outer surface of the surface layer; at least a portion of the outer surface of the electrophotographic member is made up of the surface of the crystals and is roughened by the crystals; On the outer surface of the electrophotographic member, a rectangular region having a length of 5 mm in a direction along the circumferential direction of the electrophotographic member and a length of 10 mm in a longitudinal direction perpendicular to the circumferential direction was arranged so that the center of the longitudinal direction of the rectangular region coincided with the center of the longitudinal direction of the electrophotographic member, and the rectangular region was divided into 200 observation regions by squares with sides of 500 μm, and the arithmetic mean height Sa of each of the observation regions was determined. In the frequency distribution of the observation area in which the arithmetic mean height Sa is used as a class and the class width is 0.05 μm, When the number of observation regions included in the observation region group X1 in which the arithmetic mean height Sa belongs to the class of 0.10 to 0.40 μm is defined as x1, x1 satisfies 160≦x1≦200, The number of the observation regions included in the observation region group X2 in which the arithmetic mean height Sa belongs to the class of 0.10 to 0.20 μm is defined as x2, When the number of the observation regions included in the observation region group X3 belonging to the class of the arithmetic mean height Sa of 0.25 to 0.40 μm is defined as x3, x1 and x2 satisfy the following formula (1), and x1 and x3 satisfy the following formula (2): 0.25・x1≦x2≦0.75・x1 (1) 0.25・x1≦x3≦0.75・x1 (2).

2. 2. The electrophotographic member according to claim 1, wherein x1 and x2 satisfy the following formula (3), and x1 and x3 satisfy the following formula (4): 0.30・x1≦x2≦0.70・x1 (3) 0.30・x1≦x3≦0.70・x1 (4).

3. 2. The electrophotographic member according to claim 1, wherein the area-average diameter z2 of the crystals in at least one of the observation regions included in the observation region group X2 is 10.0 to 25.0 μm.

4. 2. The electrophotographic member according to claim 1, wherein the crystals have an area-average diameter z3 of 35.0 to 60.0 μm in at least one of the observation regions included in the observation region group X3.

5. 2. The electrophotographic member according to claim 1, wherein, when the arithmetic mean thickness of the surface layer is determined in the 200 observation regions, the difference Δt between the maximum value of the arithmetic mean thickness and the minimum value of the arithmetic mean thickness is 2.00 μm or less.

6. 2. The electrophotographic member according to claim 1, wherein the surface layer has a thickness of 10 to 30 μm.

7. 2. The electrophotographic member of claim 1, wherein said electrophotographic member is an electrophotographic belt having an endless configuration.

8. 8. The electrophotographic member of claim 7, wherein the electrophotographic member is a fuser belt.

9. A fixing device in an electrophotographic image forming apparatus, The fixing device includes a fixing member and a pressure member disposed opposite the fixing member, A fixing device, wherein at least one of the fixing member and the pressure member is the electrophotographic member according to any one of claims 1 to 8.

10. An electrophotographic image forming apparatus including a fixing device, The fixing device includes a fixing member and a pressure member disposed opposite the fixing member, 9. An electrophotographic image forming apparatus, wherein at least one of said fixing member and said pressure member is the electrophotographic member according to claim 1.

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