Rotating body for fixing, heat-fixing device, and electrophotographic image forming apparatus

Abstract

To provide a rotating body for fixing that can prevent the generation of wrinkles even after a long-term use without causing restrictions on material selection and the occurrence of uneven glossiness.SOLUTION: A rotating body for fixing is provided. The rotating body for fixing is provided at least with an endless-shape base layer, an elastic layer on an outer peripheral surface of the base layer, and a surface layer fixed to an outer peripheral surface of the elastic layer with an adhesive layer therebetween. An internal stress B, which is represented by a predetermined formula, of a sample sampled from the surface layer is -3.0% or less.SELECTED DRAWING: Figure 8

Description

[Technical Field]

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

[0002] Rotating fixing bodies used in thermal fixing devices of electrophotographic image forming apparatuses (hereinafter also referred to as "image forming apparatuses") such as printers, copiers, and facsimiles include belt-shaped and roller-shaped rotating fixing bodies. For example, a rotating fixing body is known that has a belt- or roller-shaped substrate made of heat-resistant resin or metal, an elastic layer made of heat-resistant rubber or the like formed on the substrate as needed, and a surface layer containing a fluororesin that has excellent releasability for toner. Here, the fluororesin contained in the surface layer is preferably a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), which has excellent heat resistance.

[0003] In recent years, from the perspective of environmental friendliness, there has been a demand for extending the lifespan of fixing rotors to reduce waste. One of the challenges in extending the lifespan of materials used in fixing rotors is the phenomenon of "surface wrinkles." This occurs when fixing rotors are used over long periods of time, and the strength of the surface material gradually decreases due to repeated heat cycles of temperature rise and fall.

[0004] For example, when a fluororesin tube material is used as the surface layer of a fixing rotor, the fluororesin tube is tightly taut and covers the surface of the fixing rotor at the time of manufacture. However, repeated heat cycles cause repeated thermal expansion and contraction of the tube material, gradually loosening the tension of the fluororesin tube. As this loosening increases, wrinkles form on the surface of the fixing rotor. If these wrinkles extend to the toner image area, image defects occur in which wrinkle marks are transferred onto the fixed toner image, requiring the fixing rotor to be replaced.

[0005] As a method for solving this problem, for example, Patent Documents 1 to 3 disclose a process for pre-heat-shrinking a fluororesin tube used in a fixing rotor. By providing heat-shrinkage, the linear expansion coefficient during heating is reduced. In other words, the amount of thermal expansion and shrinkage during a heat cycle is reduced, which reduces loosening of the tension of the surface layer and suppresses the occurrence of wrinkles. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-200954 [Patent Document 2] Japanese Patent Publication No. 2020-106561 [Patent Document 3] Japanese Patent Application Laid-Open No. 2009-186617 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the present inventors have found that the inventions described in Patent Documents 1 to 3 have the following problems. In most cases, heat shrinkage is imparted to fluororesin tubes manufactured by extrusion molding after extrusion, which increases the number of tube manufacturing steps and increases manufacturing costs.In addition, only fluororesin materials that can be heat-shrinked can be used, which places restrictions on material selection.

[0008] Furthermore, when a heat-shrinkable fluororesin tube is used, the elastic layer is tightened by the heat shrinkage of the tube during manufacturing, which increases the apparent hardness of the fixing rotor, reducing the ability of the fixing rotor to conform to the unevenness of the media, which can result in gloss unevenness.

[0009] In addition, to prevent "surface wrinkles," it is also effective to increase the linear expansion coefficient of the elastic layer at the actual operating temperature and apply tension to the surface layer. To increase the linear expansion coefficient of the elastic layer, it is effective to minimize the amount of heat-conductive filler in the rubber of the elastic layer, but in this case, the heat conductivity of the elastic layer may be impaired, and fixability may decrease.

[0010] At least one aspect of the present disclosure is directed to providing a fixing rotating body that can suppress the occurrence of wrinkles even with long-term use without imposing restrictions on material selection or causing uneven gloss or the like. At least one aspect of the present disclosure is directed to providing a thermal fixing device including the above-described fixing rotor. The present disclosure also provides an electrophotographic image forming apparatus having the above heat fixing device. [Means for solving the problem]

[0011] The present disclosure provides a fixing rotating body, The fixing rotor comprises at least a base layer having an endless shape; an elastic layer on the outer peripheral surface side of the base layer; a surface layer fixed to the outer peripheral surface side of the elastic layer via an adhesive layer, When the length of a measurement sample taken from the surface layer in the direction of the rotation axis of the fixing rotor at 25°C is defined as L1s, and the measurement sample is pulled in the direction of the rotation axis of the fixing rotor with a load of 25 mN while being heated from 25°C to 250°C at a heating rate of 10°C / min, held at that temperature for 5 minutes, and then cooled from 250°C to 25°C at a cooling rate of 10°C / min, the length when the result is defined as L2s, the internal stress B represented by the following formula (i) is -3.0% or less, B(%)=(L2s-L1s) / L1s×100 (i) The present invention relates to a fixing rotating body characterized by the above-mentioned. [Effects of the Invention]

[0012] According to at least one aspect of the present disclosure, it is possible to obtain a fixing rotating body that can suppress the occurrence of wrinkles even after long-term use and can suppress gloss unevenness. Furthermore, according to at least one aspect of the present disclosure, it is possible to obtain a thermal fixing device including the fixing rotor. According to at least one aspect of the present disclosure, an electrophotographic image forming apparatus including the thermal fixing device can be obtained. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a schematic cross-sectional view of an example of an image forming apparatus. [Figure 2] FIG. 2 is a schematic cross-sectional view showing the configuration of a fixing device. [Figure 3] FIG. 2 is a cross-sectional view of a fixing belt. [Figure 4] 1A and 1B are a top view and a cross-sectional view of an example of a corona charger. [Figure 5] 3A and 3B are diagrams showing a first cross section and a second cross section of an elastic layer of a belt-shaped fixing rotary member. [Figure 6] 3A and 3B are schematic diagrams showing a method for confirming the degree and angle of alignment of fillers in an elastic layer. [Figure 7] FIG. 2 is a partially enlarged view of a grid used in a corona charger. [Figure 8] FIG. 1 is a diagram of a TMA curve in an embodiment of the present disclosure. [Figure 9] 1 is an example of a DSC chart of a surface sample. DETAILED DESCRIPTION OF THE INVENTION

[0014] In the present disclosure, 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. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined arbitrarily. Furthermore, in the present 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. Note that when XX is a group, multiple XXs may be selected, and the same applies to YY and ZZ.

[0015] Specific examples (examples) of embodiments of the present disclosure will be described below with reference to the drawings, but the present disclosure is not limited to the following examples. 1 is a schematic cross-sectional view of a color electrophotographic printer, which is an example of an image forming apparatus including a fixing rotor according to an embodiment of the present disclosure, taken along the sheet conveyance direction. Hereinafter, in this specification, the color electrophotographic printer will be simply referred to as the "printer." The printer 1 shown in FIG. 1 includes image forming units 10 for the colors Y (yellow), M (magenta), C (cyan), and Bk (black). A photosensitive drum 11 is pre-charged by a charger 12. A latent image is then formed on the photosensitive drum 11 by a laser scanner 13. The latent image is then converted into a toner image by a developing unit 14. The toner image on the photosensitive drum 11 is sequentially transferred by a primary transfer blade 17 to an image carrier, such as an intermediate transfer 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.

[0016] Meanwhile, sheets P are fed one by one from the paper feed cassette 20 or the multi-paper feed tray 25 in the direction of arrow 3 and fed into the registration roller pair 23. The registration roller pair 23 temporarily receives the sheet P and straightens it out if it is skewed. The registration roller pair 23 then synchronizes with the toner image on the intermediate transfer belt 31 and feeds the sheet 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 sheet P by a transfer body, such as the secondary transfer roller 35. The toner image on the sheet P is then fixed to the sheet P by heating and pressing the sheet P by the fixing device 40.

[0017] Next, a thermal fixing device according to the present disclosure will be described. The thermal fixing device according to the present disclosure has a heating member, which is a fixing rotatable body according to the present disclosure, and a pressure member arranged opposite the heating member. Figure 2 is a schematic cross-sectional view of fixing device 40, which is an example of a thermal fixing device according to the present disclosure. Fixing device 40 in Figure 2 is a belt heating type heating device (tensionless type).

[0018] The fixing device 40 is equipped with a ceramic heater 43 (hereinafter referred to as the 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 the substrate. The heater 43 is a low-heat-capacity heater that rises in temperature with a steep rise characteristic as a whole when current is applied to the heat-generating resistor layer.

[0019] The fixing rotator according to the present disclosure can be used as, for example, a heating member. One embodiment of the fixing rotator according to the present disclosure is a fixing belt having an endless belt shape. The fixing belt 41 is a cylindrical (endless) heat-resistant fixing belt that serves as a heating member for transmitting heat, and is loosely fitted around a support member (heater holder) 46 including the heater 43. The fixing belt 41 according to one embodiment of the present disclosure is as shown in FIG. 3, and has at least a surface layer The fixing belt has a composite structure of an elastic layer 41a, an elastic layer 41c, and a base layer 41d.

[0020] 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. The fixing belt 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 belt 41 against the elasticity of the elastic layer, forming a fixing nip portion of a predetermined width as a heating portion.

[0021] The pressure roller 44 is driven to rotate counterclockwise as indicated by the arrow at a predetermined peripheral speed by a driving means (not shown). The rotation of the pressure roller 44 generates a frictional force between the pressure roller 44 and the fixing belt 41 at the fixing nip, which acts as a rotational force on the cylindrical fixing belt 41. The fixing belt 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 member for the cylindrical fixing belt 41.

[0022] The pressure roller 44 is driven to rotate, and the cylindrical fixing belt 41 is driven to rotate accordingly. The heater 43 is energized, causing the heater to heat up quickly to a predetermined temperature, thereby achieving a temperature-regulated state. In this state, a sheet P carrying an unfixed toner image T is introduced between the fixing belt 41 and the pressure roller 44 in the fixing nip. The toner image-bearing side of the sheet P then comes into close contact with the outer surface of the fixing belt 41 in the fixing nip, and the sheet P is sandwiched and transported together with the fixing belt 41 into the fixing nip. During this sandwiching and transport process, the sheet P is heated by the heat of the fixing belt 41, which is generated by the heater 43, and the unfixed toner image T on the sheet P is heated and pressurized onto the sheet P, melting and fixing it. Having passed through the fixing nip, the sheet P separates from the surface of the fixing belt 41 and is then discharged and transported.

[0023] Reference numeral 45 denotes a contact thermometer (thermistor), which measures the temperature of the fixing belt 41 heated by the heater 43, and transmits the detection result to a temperature control means (not shown). A heater holder 46 is a member that holds the heater 43 when it has been heated to a high temperature.

[0024] Next, the fixing belt will be described in detail. The fixing belt of the present disclosure includes a base layer 41d having an endless shape, an elastic layer 41c provided on the outer peripheral surface side of the base layer, and a surface layer 41a on the outer peripheral surface side of the elastic layer 41c.

[0025] An example of a fixing belt according to the present disclosure is shown in Fig. 3. Fixing belt 41 has base layer 41d, elastic layer 41c covering the outer surface of base layer 41d, and surface layer 41a covering the surface of the elastic layer opposite to the side facing the base layer. Fixing belt 41 may also have resin layer 41b, which is an adhesive layer, on the surface of elastic layer 41c opposite to the side facing the base layer.

[0026] (1) Base layer The material of base layer 41d is not particularly limited, and known materials used for base layers of fixing belts and other rotating bodies can be used. Examples include metals and alloys such as aluminum, iron, stainless steel, and nickel, as well as heat-resistant resins such as polyimide. The base layer preferably contains at least one selected from the group consisting of nickel, copper, iron, and aluminum, and more preferably stainless steel. The thickness of base layer 41d is not particularly limited, but is preferably 20 μm to 100 μm, and more preferably 20 μm to 50 μm, from the viewpoints of strength, flexibility, and heat capacity.

[0027] The outer surface of the base layer 41d may be subjected to a surface treatment to provide adhesion to the elastic layer, which may include physical treatments such as blasting, lapping, and polishing, and chemical treatments such as oxidation, coupling agent treatment, and primer treatment, either singly or in combination.

[0028] The surface of the base layer 41d is preferably subjected to a primer treatment to improve adhesion between the base layer and the elastic layer. Examples of the primer used for the primer treatment include paints prepared by appropriately blending and dispersing a silane coupling agent, a silicone polymer, a hydrogenated methylsiloxane, an alkoxysilane, a reaction-accelerating catalyst, and a colorant such as red iron oxide in an organic solvent.

[0029] The primer can be appropriately selected depending on the material of the base layer, the type of the elastic layer, or the form of crosslinking reaction. In particular, when the elastic layer contains a large amount of unsaturated aliphatic groups, a primer containing a hydrosilyl group is preferably used to impart adhesion by reacting with the unsaturated aliphatic groups. When the elastic layer contains a large amount of hydrosilyl groups, a primer containing an unsaturated aliphatic group is preferably used. Other examples of primers include those containing alkoxy groups. Commercially available primers can be used. The primer treatment includes applying the primer to the outer surface of the base layer (the surface to be bonded to the elastic layer) and drying or baking it.

[0030] (2) Elastic layer The elastic layer is a layer that imparts flexibility to the fixing rotor to ensure a fixing nip in a thermal fixing device. When the fixing rotor is used as a heating member that comes into contact with toner on paper, the elastic layer also functions as a layer that imparts flexibility to the surface of the heating member so that it can follow the unevenness of the paper.

[0031] The material of the elastic layer can be any known material and is not particularly limited, but preferably contains rubber as a matrix and a thermally conductive filler dispersed in the rubber. More specifically, the elastic layer contains rubber and a thermally conductive filler, and is preferably composed of a cured product obtained by curing a composition containing at least rubber raw materials (base polymer, crosslinking agent, etc.) and the thermally conductive filler. In particular, it is preferable that the elastic layer contains silicone rubber.

[0032] The rubber is preferably silicone rubber. A composition containing at least rubber raw materials (base polymer, crosslinking agent, etc.) and a thermally conductive filler is hereinafter also referred to as a silicone rubber composition. When the silicone rubber composition is liquid, the thermally conductive filler is easily dispersed, and the elasticity of the elastic layer to be produced can be easily adjusted by adjusting the degree of crosslinking depending on the type and amount of the thermally conductive filler. The matrix has a function of imparting elasticity to the elastic layer. From the viewpoint of imparting the above-mentioned function of the elastic layer, the matrix preferably contains silicone rubber. Silicone rubber is preferable because it has high heat resistance that allows it to maintain flexibility even in an environment where the temperature in the non-paper passing area reaches a high temperature of about 240°C.

[0033] The elastic layer can be formed, for example, by applying an addition-curing liquid silicone rubber to the outer surface of the base layer and then curing it by heating. There are no particular restrictions on the application method, and any known method may be used. The thickness of the elastic layer can be appropriately designed taking into consideration the surface hardness of the fixing rotor 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. As the silicone rubber, for example, a cured product of an addition-curing type liquid silicone rubber composition described later can be used. The elastic layer is formed by coating a liquid silicone rubber mixture by a known method. It can be formed by heating.

[0034] The liquid silicone rubber composition typically contains the following components (a) to (d): 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 Each component will be described below.

[0035] Component (a): Linear organopolysiloxane having an unsaturated aliphatic group The linear organopolysiloxane having an unsaturated aliphatic group is an organopolysiloxane having an unsaturated aliphatic group such as a vinyl group, and has a structure in which siloxane bonds are connected in a linear chain. Examples of the linear organopolysiloxane having an unsaturated aliphatic group include at least one selected from the group consisting of compounds represented by the following formula (1) and compounds represented by formula (2):

[0036] [ka] In formula (1), m 1 represents an integer of 0 or more (preferably 500 to 1100), and n 1 represents an integer of 3 or more (preferably 10 to 40). 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.

[0037] [ka] In formula (2), n 2 represents an integer of 1 or more (preferably 500 to 1100), 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. In formula (1) and formula (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:

[0038] 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).

[0039] The organopolysiloxanes represented by formula (1) and formula (2) have at least one methyl group directly bonded to the silicon atom that forms the chain structure. 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.

[0040] In addition, in formula (1) and formula (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.

[0041] From the viewpoint of moldability, the viscosity of component (a) is 1000mm 2 / s or more 20000mm 2 / s or less is preferable, and 3000 mm 2 / s or more 8000mm 2 / s or less is more preferable. 2 / s or more, it is easy to adjust the hardness required for the elastic layer, and 2 When the viscosity is 1 / s or less, the filler can be easily oriented by an electric field. The viscosity (kinematic viscosity) can be measured using a capillary viscometer, a rotational viscometer, or the like in accordance with JIS Z 8803:2011. The amount of component (a) is preferably 55% by volume or more based on the silicone rubber composition used to form the elastic layer from the viewpoint of durability, and 70% by volume or less from the viewpoint of heat conductivity.

[0042] Component (b): Organopolysiloxane having silicon-bonded active hydrogen 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.

[0043] Specific examples of component (b) include the linear organopolysiloxane shown in formula (3) below and the cyclic organopolysiloxane shown in formula (4) below.

[0044] [ka] In structural formula (3), m 2 represents an integer of 0 or more (preferably 10 to 30), and n 3 represents an integer of 3 or more (preferably 5 to 20), and R 5 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group.

[0045] [ka] In formula (4), m 3 represents an integer of 0 or more (preferably 10 to 30), and n 4 represents an integer of 3 or more (preferably 5 to 20), and R 6 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group.

[0046] R in formula (3) and formula (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.

[0047] Component (c): Catalyst 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.

[0048] Component (d): Thermally conductive filler Thermally conductive fillers (hereinafter simply referred to as fillers) are selected taking into consideration their own thermal conductivity, specific heat capacity, density, particle size, dielectric constant, etc. Thermally conductive fillers used to improve the heat transfer properties of inorganic substances, particularly metals and metal compounds, include the following: silicon carbide, silicon nitride, boron nitride, aluminum nitride, alumina, zinc oxide, magnesium oxide, silica, copper, aluminum, silver, iron, nickel, metallic silicon, and carbon fiber.

[0049] Furthermore, from the viewpoint of the thermal conductivity, electrical resistance, and dielectric constant of the filler itself, it is more preferable that the filler is at least one type of filler selected from the group consisting of alumina, zinc oxide, metallic silicon, silicon carbide, boron nitride, and magnesium oxide. Also, from the viewpoint of the heat resistance of the elastic layer, the ionic impurities (Na + Metallic silicon and silicon carbide, which have less of the above-mentioned ions, are more preferable.

[0050] In the fixing rotating body according to the present disclosure, the internal stress B represented by the formula (i) described below of a measurement sample taken from the surface layer is −3.0% or less. An internal stress B of -3.0% or less is thought to mean that the crystallization of the resin that makes up the surface layer is sufficiently promoted. As a result, the linear expansion coefficient of the surface layer is small, and the tension of the surface layer is less likely to loosen even with repeated heat cycles, preventing the occurrence of wrinkles. To make the internal stress B of the surface layer -3.0% or less, for example, there is a method of heating the surface layer above its melting point and pulling it in the axial and circumferential directions of the fixing rotor, thereby growing crystals and applying internal stress to the crystalline part of the polymer in the surface layer. As a method of pulling the surface layer, the surface layer may be pulled mechanically, but it is also possible to adhere the surface layer onto an elastic layer and heat the underlying elastic layer. The surface layer may be stretched by expanding. The internal stress B is preferably −3.0% to −6.0%, and more preferably −4.0% to −5.0%.

[0051] The linear expansion coefficient of the elastic layer can be measured using a TMA curve, with temperature on the horizontal axis and linear expansion coefficient on the vertical axis, obtained by pulling a measurement sample taken from the elastic layer in the axial direction of the fixing rotor with a load of 25 mN, raising the temperature from 25°C to 250°C at a heating rate of 10°C / min, holding the temperature for 5 minutes, and then lowering the temperature from 250°C to 25°C at a cooling rate of 10°C / min. In this case, it is preferable that the linear expansion coefficient A of the elastic layer in the axial direction of the fixing rotor, represented by formula (ii), and the linear expansion coefficient A2 in the circumferential direction, represented by formula (iii), are each 0.0175% / °C or higher. This allows crystal formation to be carried out while applying internal stress to the surface layer in the axial direction and circumferential direction of the fixing rotor in the surface layer processing step described below, which is thought to further reduce the linear expansion coefficient of the surface layer.

[0052] The linear expansion coefficient A of the elastic layer in the rotation axis direction of the fixing rotor and the linear expansion coefficient A2 in the circumferential direction are each preferably 0.005 to 0.030% / °C, more preferably 0.010 to 0.025% / °C, and even more preferably 0.015 to 0.020% / °C.

[0053] The linear expansion coefficient of the elastic layer is determined by the ratio of a rubber such as silicone rubber as a matrix, which has a large linear expansion coefficient as a single substance, to a thermally conductive filler, which has a small linear expansion coefficient as a single substance. However, increasing the silicone rubber ratio in an attempt to increase the linear expansion coefficient reduces thermal conductivity, so it is preferable to achieve thermal conductivity with a small amount of filler by orienting the filler in the thickness direction using an electric field orientation process described below. Furthermore, compared to a configuration in which the filler is randomly arranged, orienting the filler in the thickness direction makes the filler relatively sparse in the two directions, the rotational axis direction and the circumferential direction, of the fixing rotor, which face the thickness direction, thereby reducing the influence of the inorganic filler. As a result, the linear expansion coefficient of the elastic layer as a whole in the rotational axis direction and the circumferential direction of the fixing rotor can be maintained high.

[0054] Since the surface is charged before the rubber is cured to orient the filler, the material is preferably electrically insulating or semiconductive, and for example, a cured silicone polymer can be used as described below.

[0055] The filler may be surface-treated from the viewpoint of affinity with silicone and electrical resistance. Specifically, fillers such as alumina, silica, and magnesium oxide, which have active groups such as hydroxyl groups on their surfaces, are surface-treated with a silane coupling agent, hexamethyldisilazane, or the like. Metal fillers are surface-treated by forming an oxide film.

[0056] Furthermore, the electrical resistance may be adjusted for the entire silicone rubber composition. By using a filler with a relatively low electrical resistance in combination with a second filler with a high electrical resistance, the electrical resistance of the entire composition can be adjusted.

[0057] The particle size of the filler is preferably 0.1 μm or more and 100 μm or less, and more preferably 0.3 μm or more and 30 μm or less. The particle size here refers to the volume average particle size. The filler content in the elastic layer is preferably 50 to 200 parts by mass, more preferably 100 to 180 parts by mass, per 100 parts by mass of silicone rubber, from the viewpoint of reducing hardness.

[0058] (2-2) Confirmation of the orientation and arrangement of the thermally conductive filler in the elastic layer When the elastic layer of the fixing rotating member according to the present disclosure contains a filler, the filler is preferably oriented and aligned in the thickness direction. The thermally conductive filler is oriented in the thickness direction of the elastic layer in the electric field orientation process described later. It is possible.

[0059] By orienting the filler in the thickness direction, it is easy to achieve thermal conductivity with a small amount of filler. Furthermore, compared to a configuration in which the filler is randomly arranged, by orienting the filler in the thickness direction, the filler becomes relatively sparse in the axial and circumferential directions of the fixing rotor, which face the thickness direction, and this reduces the influence of inorganic fillers with a small linear expansion coefficient. As a result, the linear expansion coefficient of the entire elastic layer can be maintained high in both the axial and circumferential directions of the fixing rotor.

[0060] The alignment state of the thermally conductive filler can be confirmed by performing a two-dimensional Fourier transform using a binarized image obtained from a cross-sectional image of the elastic layer. Specifically, the procedure is as follows. First, a measurement sample is prepared. For example, if the fixing rotator is a fixing belt 41 as shown in FIG. 5A, a sample 401 measuring 5 mm long, 5 mm wide, and the full thickness of the fixing belt is prepared as shown in FIG. 5B. Specifically, a 5 mm section is taken from the center of the fixing belt in the axial direction, covering the entire circumference, and a 5 mm x 5 mm rectangular sample is obtained. The sample is then cut at equal intervals of 5 mm along the circumference, resulting in a total of 10 5 mm x 5 mm samples. Five of the 10 samples are polished using an ion beam at the circumferential cross section of the fixing belt, i.e., a cross section including a first cross section 401-1 in the circumferential direction of the elastic layer. For the remaining five samples, a cross section perpendicular to the circumferential direction of the fixing belt, i.e., a cross section including a second cross section 401-2 in the axial direction of the elastic layer, is polished using an ion beam. A cross-section polisher is used to polish the cross sections using an ion beam. Polishing the cross section using an ion beam can prevent the filler from falling off the sample and the abrasive from getting mixed in, and can also form a cross section with fewer polishing marks.

[0061] Next, for five samples in which the first cross section of the elastic layer was polished, and for five samples in which the second cross section of the elastic layer was polished, each polished cross section was observed using a laser microscope (OLS3000, Olympus, using a 50x objective lens) or a scanning electron microscope (SEM) (S4700, Hitachi), and cross-sectional images of a 150 μm × 100 μm area were obtained (Figure 6A). Next, the obtained image is converted to black and white using commercially available image software (Image-J) so that the filler area appears white and the silicone rubber area appears black (Figure 6B). The Otsu method is used for the binarization.

[0062] Furthermore, by performing two-dimensional Fourier transform analysis on the filler image, ellipse plots showing the direction and degree of filler alignment were obtained (Figures 6C and 6D, respectively). Because the two-dimensional Fourier transform itself has a peak in the direction perpendicular to the periodicity of the binarized image, the ellipse plots are the results of two-dimensional Fourier transforms with a phase shift of 90°. The alignment angle Φ can be calculated from the angle formed by the semi-major axis of this ellipse plot, and the filler alignment degree f, defined as f = 1-(y / x) where the semi-major axis is x and the semi-minor axis is y, can be calculated.

[0063] 6C and 6D, the 90°-270° direction indicates the thickness direction of the elastic layer, and the 0°-180° direction indicates the circumferential direction or rotation axis direction of the elastic layer. Therefore, the closer the arrangement angle Φ is to 90°, the more the filler is aligned in the thickness direction. The degree of alignment f represents the flattening of the ellipse and is a value between 0 and 1. When f is 0, the ellipse becomes a circle, representing a completely random state with no alignment; as f approaches 1, the ellipse becomes more flattened and the degree of alignment of the filler also increases.

[0064] In this way, the thickness of the elastic layer - 150 μm × 100 μ at five points on the first cross section in the circumferential direction A total of 10 binarized images are obtained: a first binarized image of 150 μm × 100 μm in size and a second binarized image of 150 μm × 100 μm in size at five locations on the second cross section in the thickness-rotation axis direction of the elastic layer. Then, in the binarized images, the average area ratio occupied by the thermally conductive filler, the average alignment degree f of the thermally conductive filler, and the average alignment angle Φ of the thermally conductive filler are measured. Each average value is calculated by averaging the values ​​at a total of 10 locations. The average degree of alignment f of the filler is preferably 0.10 to 0.50, and more preferably 0.13 When f is 0.10 or more, thermal conductivity is easily exhibited, and when f is 0.50 or less, low hardness of the elastic layer is easily achieved. The average degree of alignment f can be controlled by the grid voltage (Vp-p), application time, frequency, etc. in the electric field application step described below.

[0065] The average arrangement angle Φ of the thermally conductive filler is preferably 28° to 90°, more preferably 30° to 90°, and may be 30° to 55°. The direction where Φ is 90° corresponds to the thickness direction of the elastic layer, so the closer Φ is to 90°, the more the filler is arranged in the thickness direction. Therefore, by keeping Φ within the above range, thermal conductivity in the thickness direction can be improved. Here, 30° and 150° are in a mirror image relationship with 90° as the boundary, and therefore have the same heat transfer function in the thickness direction. Therefore, the arrangement angle is expressed as 0° to 90°. The average orientation angle Φ can be controlled by the grid voltage (Vp-p), application time, frequency, etc. in the electric field application step described below.

[0066] The average area percentage (%) of the thermally conductive filler is preferably 27 to 45%, more preferably 30 to 45%. Here, the area percentage of the filler refers to [(total area of ​​the filler in the binarized image × 100) / (area of ​​the binarized image)]. When the average area percentage of the filler is 27% or more, the distance between the fillers is appropriate, a sufficiently large local electric field can be generated when an electric field is applied, and sufficient alignment can be achieved. Furthermore, when the average area percentage of the filler is 45% or less, the hardness of the elastic layer can be sufficiently reduced.

[0067] (2-3) Step of applying an electric field to the elastic layer The corona charger 2 and the process of applying an electric field to the elastic layer using the corona charger are described below as one embodiment. Corona charging methods include the scorotron method, which has a grid electrode between the corona wire and the object to be charged, and the corotron method, which does not have a grid electrode. However, the scorotron method is preferred from the viewpoint of controllability of the surface potential of the object to be charged.

[0068] 4A and 4B, the corona charger 2 includes a front block 201, a rear block 202, and shields 203 and 204. A discharge wire 205 is stretched between the front block 201 and the rear block 202, and when a charging bias is applied from a high-voltage power supply, the discharge wire 205 discharges and charges the surface of the uncured elastic layer 41c on the base layer, which serves as a body to be charged.

[0069] Similar to the configuration of a typical corona charger, a high voltage is applied to discharge wire 205, which serves as a discharge member. The ion flow obtained by discharge to shields 203 and 204 is controlled by applying a high voltage to grid 206, thereby controlling the surface of elastic layer 41c to a desired charged potential. At this time, since base layer 41d or core 101 holding base layer 41d is grounded (not shown), it is possible to generate a desired electric field in elastic layer 41c by controlling the surface potential of the surface of elastic layer 41c.

[0070] To explain in detail the manufacturing method of the fixing rotator of the above embodiment, first, an elastic layer made of silicone rubber containing a thermally conductive filler is formed on a base layer. Next, as shown in Figure 4A, corona chargers 2 are arranged in close proximity to each other along the width direction of uncured elastic layer 41c of fixing belt 41. Then, a voltage is applied to grid 206 of corona charger 2, and fixing belt 41 is rotated at 141 rpm for 160 seconds in a discharged state, thereby charging the surface of the elastic layer. The distance between the surface of the elastic layer and the grid 206 can be set to 1 mm to 10 mm. By charging the surface of the elastic layer 41c in this way, an electric field is generated within the elastic layer, which orients the thermally conductive filler. Thereafter, the elastic layer is hardened by heating or the like, thereby fixing the orientation of the filler.

[0071] From the viewpoint of generating an effective electrostatic interaction in the filler, the voltage applied to the grid 206 is preferably in the range of 0.1 kV to 3 kV in absolute value (0.2 to 6 kV in Vp-p in the case of AC application). When using an electric field to form the filler orientation in the thickness direction of the elastic layer, it is important to generate an electric field in the thickness direction of the elastic layer 41c. If the sign of the applied voltage is the same as the sign of the voltage applied to the wire, the direction of the electric field will be opposite whether it is negative or positive, but the effect obtained will be the same.

[0072] Furthermore, when AC charging is used to suppress the liquid surface flow described below, it is desirable to match the waveform phases of the wire and grid. Depending on the type of thermally conductive filler, it may be difficult to form an orientation of the irregular filler. In this case, it is desirable to increase the voltage applied to the grid 206. This is presumably related to the dielectric constants of the silicone rubber component and the thermally conductive filler. If the difference in dielectric constant between the silicone rubber and the filler is large, it is possible to form an orientation of the irregular filler with a relatively small applied voltage.

[0073] On the other hand, if the voltage applied to the grid 206 is too high, the electrostatic repulsive force due to the surface charge of the elastic layer will increase, causing the liquid surface to flow, which may result in a decrease in the surface properties of the elastic layer 41c. Therefore, it is more preferable that the voltage applied to the grid 206 be in the range of 0.1 kV to 1.5 kV in absolute value (1.2 to 3 kV in Vp-p when AC is applied). This liquid surface flow can be alleviated by applying AC charging.

[0074] Here, we will explain the grid as a control electrode stretched in the longitudinal direction of the opening of the corona charger. Hereinafter, unless otherwise specified, the grid refers to a grid having a plurality of openings (through holes) that penetrate the grid in a mesh pattern. Fig. 7 is an enlarged view of part of grid 206 viewed from the elastic layer side to explain an example of the grid's outer shape.

[0075] As shown in FIG. 7, the central portion of grid 206 in the short direction (the direction in which shields 203 and 204 in FIG. 4B face each other) is mesh-shaped, and both ends of the short direction are beam portions with a width of 1.5±0.1 mm, as shown in (6). The width of the through-holes in grid 206 is 0.312±0.03 mm, as shown in (1). The angle of the through-holes with respect to the longitudinal direction of grid 206 is 45±1°, as shown in (3). (2) is the thickness of the mesh material, which is 0.071±0.03 mm. In addition, between the mesh portions, beams with a width of 0.1±0.03 mm, as shown in (4), are arranged in the longitudinal direction at intervals of 6.9±0.1 mm, as shown in (5), to suppress deflection of grid 206.

[0076] From the viewpoint of making the charged potential on the surface of the elastic layer more uniform, it is preferable to etch a shape pattern including a width of 1.0 mm or less for the through-holes of the mesh. Furthermore, the higher the area ratio of the mesh portion to the through-hole portion, the easier it is to make the charged potential uniform. A flat grid 206 can be placed between the discharge wire 205 and the surface of the elastic layer, and from the viewpoint of making the charged potential on the surface of the elastic layer more uniform, it is preferable that the distance between the surface of the elastic layer and the grid 206 be in the range of 1 mm to 10 mm.

[0077] As shown in Figure 7, this flat grid 206 is tensioned by tensioning sections disposed on the front block 201 and the rear block 202. By operating the knobs on the tensioning sections, the support of the grid 206 is released, making it easy to attach and detach. Furthermore, a bent shape is given to a part of the flat plate of the grid 206 near the tensioning section, giving it some flexibility. Therefore, even when the grid 206 is stretched over the corona charger 2, it can move to some extent when subjected to an external force. The flat grid may be a mesh-like one as shown in Fig. 7, but is not limited to this shape. For example, it may be a flat grid with a honeycomb structure as shown in JP 2005-338797 A.

[0078] For example, the configuration shown in FIG. 4A can be used to control the potential of the surface of the elastic layer in the direction of the rotation axis of the fixing rotor. While a voltage is being applied to the grid 206, the entire elastic layer 41c can be charged by rotating the core 101 around its central axis. The rotation speed of the fixing rotor is preferably 10 rpm to 500 rpm, and the treatment time is preferably 20 seconds or longer to ensure stable alignment of the filler. The treatment time can be, for example, 20 to 200 seconds. Thus, by controlling the surface potential and the time for applying the electric field, it is possible to control the alignment of the irregular filler.

[0079] Although stainless steel, nickel, molybdenum, tungsten, etc. may be used for the discharge wire 205, it is preferable to use tungsten, which is an extremely stable metal. The discharge wire stretched inside the shield may have a circular cross section or a sawtooth shape.

[0080] Furthermore, the diameter of the discharge wire 205 is preferably 40 μm to 100 μm. By keeping the diameter of the discharge wire within this range, it is possible to prevent the discharge wire from being cut by ions during discharge, and it is also possible to eliminate the need to increase the voltage required to generate a corona discharge excessively. Either a DC voltage or an AC voltage can be used as the voltage applied to the discharge wire 205. In the case of an AC voltage, a frequency of approximately 0.01 Hz to 1000 Hz is preferred. The voltage can be generated by outputting a square wave, a sine wave, or the like using an arbitrary waveform generator.

[0081] (3) Adhesive layer The adhesive layer is not particularly limited as long as it can bond the elastic layer and the surface layer. For example, an addition-curing silicone rubber adhesive can be used. An addition-curing silicone rubber adhesive contains uncrosslinked silicone rubber components, and when heated, it bonds with the uncrosslinked components of the inner surface treatment layer of the surface layer and the elastic layer, thereby bonding the surface layer and the elastic layer. Specifically, it contains an organopolysiloxane having multiple unsaturated aliphatic groups, typically vinyl groups, in its molecular chain, a hydrogenorganopolysiloxane, and a platinum compound as a crosslinking catalyst. It then hardens by an addition reaction. Known adhesives can be used as such adhesives.

[0082] The thickness of the adhesive layer is preferably 20 μm or less. By setting the thickness to 20 μm or less, the thermal resistance of the fixing rotor can be set low, and heat from the inner surface (base layer side) can be efficiently transferred to the recording material (recording medium). The thickness of the adhesive layer can be, for example, 1 to 20 μm or 2 to 10 μm.

[0083] (4) Surface layer The material of the surface layer 41a is not particularly limited, but preferably contains a fluororesin. Examples of fluororesins include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer (PFA), with PFA being preferred from the viewpoint of releasability and rigidity. Commercially available PFA can be used. Specific examples include AP-230 (trade name, manufactured by Daikin Industries, Ltd.), AP-231SH (trade name, manufactured by Daikin Industries, Ltd.), which is a PFA with fully fluorinated terminal groups, and 451HP-J (trade name, manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd.), which has a small spherulite size. can be done. The thickness of the surface layer 41a is preferably 100 μm or less, and more preferably 10 to 70 μm.

[0084] The adhesiveness of the inner surface of the surface layer 41a can be improved by previously treating it with sodium, excimer laser, ammonia, or plasma etching. In the examples of the present disclosure, a PFA tube with a thickness of 20 μm obtained by extrusion molding was used. The surface layer is preferably not a heat-shrinkable tube, as this can prevent an increase in hardness in the center, make it difficult for conformability to decrease, and maintain flexibility, thereby further suppressing gloss unevenness.

[0085] The PFA tube can be produced, for example, by extruding molten PFA through a cylindrical die. Such a PFA tube is rapidly cooled during the extrusion process, causing rapid crystallization, resulting in crystals oriented in the extrusion direction and a low degree of crystallinity. After the PFA tube is coated on the surface of the elastic layer 41c to form the surface layer 41a, the surface layer is subjected to a heat treatment, as described below, to increase the degree of crystallinity and form spherulites on the surface of the surface layer.

[0086] In the present disclosure, a measurement sample taken from the surface layer 41a is pulled in the direction of the rotation axis of the fixing rotor with a load of 25 mN while being heated from 25°C to 250°C at a temperature increase rate of 10°C / min to obtain a TMA curve with the horizontal axis being temperature and the vertical axis being linear expansion coefficient. The linear expansion coefficient at a temperature of 200°C is defined as C. C is, for example, -0.5 to 2.0%, and preferably 0 to 1.5% or less. If C is 1.5% or less, surface wrinkles are less likely to occur after durability testing. If the content is 0% or more, gloss unevenness can be further suppressed. The method for sampling the measurement sample and the method for obtaining the TMA curve will be described later in the Examples.

[0087] The linear expansion coefficient C can be controlled by the crystallinity of the surface layer. For example, by subjecting the surface layer to a heat treatment to increase the crystallinity, the linear expansion coefficient C can be easily reduced. It is preferable to control the heat treatment and cooling rate on the elastic layer. By controlling the heat treatment and cooling rate on an elastic layer with a relatively high linear expansion coefficient, crystalline portions are easily formed when stress is applied in the direction of the rotation axis of the fixing rotor. Furthermore, controlling the cooling rate makes it easier to increase the number of crystalline portions. As a result, the linear expansion coefficient is easily reduced.

[0088] Furthermore, when a measurement sample taken from the surface layer 41a is subjected to calorimetry using a differential scanning calorimeter (DSC) by heating from 25°C to 400°C at a heating rate of 20°C / min, the endothermic curve preferably shows an endothermic amount of 21 J / g or more during the heating process. Hereinafter, an example will be described in which the surface layer 41a is made of PFA, but the present invention is not limited to this.

[0089] The heat absorbed during the temperature rise process is the heat absorbed due to the crystalline melting of PFA. The crystallinity of PFA can be calculated by dividing the heat absorbed value by the heat of complete crystalline melting of PTFE (92.9 J / g). When the heat absorbed is 21 J / g or more, there are many crystalline parts that have been given the internal stress mentioned above, and the linear expansion coefficient of the fixing rotor in the axial direction and circumferential direction can be reduced.

[0090] One method for achieving an endothermic capacity of 21 J / g or more is to heat the surface layer 41a formed during the manufacturing process of the fixing rotor to a temperature above the melting point of PFA, and then control the cooling rate to promote crystallization of PFA. Although the specific method is not particularly limited, the following methods for heat treatment of the surface layer can be used.

[0091] In order to heat the entire fixing rotor, a vertical cylindrical heating element capable of heating up to 330°C or more is used. A heating cylinder is used. A band heater equipped with a thermocouple is installed inside the heating cylinder to control the heating temperature of the fixing rotor. The heating temperature is preferably above the melting point of PFA and below 380°C. The heating time may be any time that allows the surface layer temperature to sufficiently reach the desired temperature, and examples include 1 to 20 minutes, 1 to 10 minutes, and 2 to 5 minutes.

[0092] After heating is complete, the cooling rate of the fixing rotor 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 slower the cooling rate in the crystallization temperature range of PFA, the more the crystallization of PFA can be promoted, and it is preferable to adjust the cooling rate so that the endothermic heat is 21 J / g or more. The cooling rate is preferably controlled until the temperature of the surface layer falls below the crystallization temperature range of PFA. The cooling rate is, for example, 5 to 50°C / min, and 10 to 30°C / min.

[0093] After heating, a cooling step can be carried out. The cooling step is, for example, as follows: After heating is completed, the heating barrel is cooled. Cooling is carried out, for example, by providing an air supply nozzle on the outer periphery of the heating barrel and adjusting the air flow rate. A relatively fast cooling rate is preferred so as not to increase the spherulite diameter. The cooling rate is preferably 100 to 500°C / min, more preferably 150 to 250°C / min. For example, the above cooling rate may be achieved by removing the material into the atmosphere (25°C) and allowing it to cool naturally. It is believed that such rapid cooling can produce multiple small spherulite crystals. (The process up to this point is called one-stage annealing treatment.)

[0094] After sufficient cooling, a second heat treatment is carried out. The same equipment as used for the first heat treatment can be used. The surface layer is heated again and maintained for a certain period of time to promote further crystallization. The heating temperature may be in the range above the glass transition temperature at which crystallization progresses and below the complete melting temperature. The second heat treatment is preferably carried out at a temperature about 10°C lower than the melting point of PFA. The heating time may be any time that the surface layer temperature reaches the desired temperature sufficiently and can be maintained at a temperature that allows crystallization to proceed for a certain period of time or longer, and is preferably 1 to 20 minutes, 1 to 10 minutes, or 2 to 5 minutes (e.g., 3 minutes).

[0095] By heating below the full melting temperature, i.e., annealing, the parts that did not crystallize in the first heat treatment crystallize, increasing the degree of crystallization. The crystals formed in the second heat treatment are more stable and highly crystalline, and are thought to correspond to peak P1 in the DSC chart described below. Furthermore, as mentioned above, because small spherulites are formed by rapid cooling in the first heat treatment, it is thought that the spherulites are unlikely to become larger even if the degree of crystallization is improved. Even though the degree of crystallinity is high, the crystals do not grow large, so the flatness of the fixing belt is not compromised, and gloss unevenness can be suppressed.

[0096] Thereafter, cooling may be carried out in the same manner as in the first heat treatment. The cooling rate is preferably 100 to 500°C / min, more preferably 150 to 250°C / min. For example, the above cooling rate may be achieved by removing the material from the atmosphere (25°C) and allowing it to cool naturally. (The above process is called two-stage annealing.)

[0097] The degree of crystallinity of the surface layer 41a can be confirmed by the following calorimetry. The sample taken from the surface layer 41a is used as a measurement sample, and calorimetry is carried out using a differential scanning calorimeter (DSC) by sequentially carrying out the following steps (1) and (2). An example of a DSC chart is shown in FIG. Step (1): A temperature-raising step of heating the measurement sample from 25°C to 400°C at a temperature-raising rate of 20°C / min (after heating, maintaining the sample at 400°C for 5 minutes); Step (2): The measurement sample heated to a temperature of 400°C in step (1) is cooled to 25°C. A cooling step in which the temperature is cooled at a rate of 20°C / min;

[0098] The fact that the surface layer has at least two endothermic peaks in the first DSC chart obtained in step (1) indicates the presence of crystals with different melting points. The presence of at least one endothermic peak in the second DSC chart obtained in step (2) indicates the presence of crystals at a certain melting point. It is preferable that at least two endothermic peaks are present in the first DSC chart. It is also preferable that at least one endothermic peak is present in the second DSC chart.

[0099] As shown in the first scan of Figure 9, the first DSC chart shows peak P2, which indicates t1, followed by peak P1, which indicates T1. When two peaks appear like this, peak P2, which is at the lower temperature, is thought to be a peak due to small spherulite crystals. Then, peak P1, which appears at a higher temperature, is a peak with a higher degree of crystallinity.

[0100] The fact that two distinct peaks appear in the first scan during the heating process, rather than a single broad peak, is thought to be due to the influence of the stable, more crystalline peak P1. That is, during the heating process, the more crystalline crystals that could become peak P1 do not melt at the temperature at which peak P2 appears, and further crystallization proceeds during the subsequent heating process up to T1. The heat generated by this crystallization is thought to be the reason for the appearance of at least two peaks, as shown in Figure 9.

[0101] Therefore, the appearance of at least two peaks during the heating process is thought to indicate the presence of small spherulite crystals and the presence of crystals with a higher degree of crystallinity. Peak P1 is thought to be a peak resulting from the promotion of the growth of the amorphous parts of the crystals that could not grow during the one-stage annealing treatment, and the melting of all the crystals contained in the surface layer, including the resulting highly crystalline crystals.

[0102] The two-stage annealing process promotes the growth of amorphous parts of the crystals that could not grow in the one-stage annealing process, thereby increasing the degree of crystallinity. As a result, the proportion of crystals to which internal stress is applied (as described below) increases, improving the internal stress in the rotation axis direction of the surface fixing rotor and suppressing the occurrence of wrinkles.

[0103] Furthermore, as mentioned above, the lower endothermic peak P2 of at least two endothermic peaks in the first DSC chart indicates the presence of small spherulites. The presence of peak P1 in addition to peak P2 suggests that crystallization at a higher temperature was carried out in the presence of small spherulites in the surface layer, resulting in crystals with peak P1. When the degree of crystallization is increased in the presence of small spherulites, the spherulites that would normally grow at high temperatures are prevented from growing by the presence of the small spherulites. Therefore, it is believed that gloss unevenness can be suppressed without impairing the surface smoothness of the surface layer.

[0104] The presence of at least two endothermic peaks in the first DSC chart is believed to indicate that the crystallinity of the surface layer is high and that the spherulites are small, which is believed to enable both wrinkle suppression and surface smoothness. [Example]

[0105] The present disclosure will be described in more detail below using examples. Example 1 The elastic layer 1 shown in Table 1 was prepared as follows to obtain the fixing belt of Example 1.

[0106] (1) Preparation of liquid addition-curable silicone rubber composition 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.

[0107] Next, 160 parts by mass of metallic silicon (product name: #350, manufactured by Kinsei Matec Co., Ltd.) as component (d) thermally conductive filler, as shown in Table 1, was added to this Vi and mixed thoroughly to obtain mixture 1.

[0108] 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.

[0109] 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.

[0110] 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 2.0 parts by mass of 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.

[0111] (2) Fabrication of the fixing belt A stainless steel endless belt with an inner diameter of 24 mm, a width of 400 μm, and a thickness of 30 μm was prepared as the base layer. During the manufacturing process, the endless belt was handled with a core inserted inside.

[0112] A primer (product name: DY39-051A / B; manufactured by Dow Corning Toray Co., Ltd.) was applied uniformly to the outer surface of the base layer so that the dry weight was 20 mg. After the solvent had dried, the base layer was baked in an electric furnace set to 160°C for 30 minutes. The silicone rubber composition was applied to the primer-treated base layer by ring coating to a thickness of 250 μm, and this is referred to as an uncured endless belt.

[0113] Next, a corona charger with a charging area width of 295 mm was placed facing the uncured endless belt along its generator line, and an AC electric field was applied to the surface of the uncured elastic layer while the uncured endless belt was rotating at 100 rpm. The conditions were: current supplied to the corona charger's discharge wire of ±150 μA, grid electrode potential of ±300 V (Vp-p: 600 V), frequency of 0.025 Hz, distance between the grid electrode and the belt of 3 mm, and charging time shown in Table 1.

[0114] This charged uncured endless belt was heated in an electric furnace at 160°C for 1 minute (primary curing), and then heated in an electric furnace at 200°C for 30 minutes (secondary curing) to cure the silicone rubber composition, thereby obtaining an endless belt with a cured elastic layer 1.

[0115] Next, an addition-curing silicone rubber adhesive (product name: SE1819CV A / B; manufactured by Toray Dow Corning Co., Ltd.) was applied uniformly to a thickness of approximately 10 μm on the surface of the elastic layer of the cured endless belt as an adhesive layer. On the other hand, a fluororesin tube (listed in Table 2, AP-231SH (product name) manufactured by Daikin Industries, Ltd.) with an inner surface etched was extruded and molded into a PFA (product name: AP-231SH; manufactured by Daikin Industries, Ltd.) with an inner diameter of 23 mm and a thickness of 20 μm as a surface layer. The fluororesin tube was laminated on an endless belt provided with an adhesive layer while expanding its diameter. The belt surface was then uniformly rubbed from above the fluororesin tube to remove excess adhesive from between the elastic layer and the fluororesin tube until the thickness was approximately 5 μm. The endless belt was heated in an electric furnace set at 200° C. for 1 hour to harden the adhesive, thereby fixing the fluororesin tube onto the elastic layer.

[0116] (3) Applying stress to the surface The obtained endless belt was inserted into a heating cylinder with an inner diameter of 42 mm and heated using a band heater inside the heating cylinder. Prior to the heat treatment, both ends of the fluororesin tube were fixed, and tension was applied at the fixing parts while the heat treatment was being performed, resulting in a stretching treatment in the axial and circumferential directions of the fixing rotor (hereinafter, this operation will be referred to as "fixed stretching"). As shown in Table 2, the heating temperature of this fixing rotor was set to 330°C, and the heating was controlled so that the actual temperature of the surface layer was above the melting temperature of PFA. The fixing rotor was stretched by 4% of its total length in the axial direction and by 4% of its circumferential length in the circumferential direction, and the heat treatment was performed while maintaining this state of stress in the axial and circumferential directions.

[0117] The heating time was set to 3 minutes, which was the time required for the surface temperature to reach the desired temperature, while applying stress in the axial and circumferential directions of the fixing rotor after placing the fixing belt in the heating barrel. After 3 minutes had passed, the heating barrel was cooled to 200°C at a rate of 20°C / min and then removed from the heating barrel into a room temperature atmosphere. Both ends of the resulting endless belt were cut to obtain a fixing belt with a width of 336.5 mm.

[0118] (3) Evaluation of the characteristics of the elastic layer of the fixing belt (3-1) Measurement of the linear expansion coefficient of the elastic layer in the rotation axis direction and circumferential direction of the fixing rotor <Method for measuring the coefficient of linear expansion> First, the elastic layer was separated from the fixing rotor by inserting a razor into the substrate-elastic layer interface and the surface layer-elastic layer interface. Thereafter, the elastic layer was cut into strips of 16 mm x 6 mm to prepare samples. When measuring the direction of the rotation axis of the fixing rotor, the direction of the rotation axis is 16 mm, the circumferential direction is 6 mm, and the circumferential direction is For the measurement, the cutting was done at 6 mm in the rotation axis direction and 16 mm in the circumferential direction.

[0119] Next, a thermomechanical analyzer (TMA) was used, and the sample was placed on a sample attachment with the top and bottom of the measurement direction fixed, and measurements were performed under the following conditions.

[0120] Apparatus: Thermomechanical analyzer TMA / SDTA2+ (trade name, manufactured by Mettler-Toledo) Load: 25mN Temperature: 25°C to 250°C at 10°C / min, then hold for 5 minutes, then cool from 250°C to 25°C at 10°C / min

[0121] The initial length of the elastic layer at 25°C is unstable during installation due to the elasticity of the rubber, so the length at 100°C during the process of heating to 250°C while applying a load of 25mN was used as the standard. The linear expansion coefficient A [% / °C] was calculated using the following formula (ii), where L1e was the length in the direction of the rotation axis at a temperature of 100°C during the temperature increase process and L2e was the length in the direction of the rotation axis at a temperature of 200°C during the temperature decrease process. A=((L2e-L1e) / L1e)×100 / (200-100) ···(ii)

[0122] Similarly, the circumferential length of the measurement sample at 100°C during the temperature rise process was defined as L3e, and the measurement sample was pulled in the circumferential direction with a load of 25 mN while being heated from 25°C to 250°C at a temperature rise rate of 10°C / min, and then held for 5 minutes.The temperature was then lowered from 250°C to 25°C at a temperature drop rate of 10°C / min.The circumferential linear expansion coefficient A2 [% / °C] was calculated using the following formula (iii): A2=(L4e-L3e) / L3e×100 / (200-100) ···(iii) The results of the linear expansion coefficients A and A2 in the rotation axis direction and circumferential direction of the fixing rotor are shown in Table 1. It became like this.

[0123] (3-3) Measurement of internal stress along the rotation axis of the surface fixing rotor The internal stress in the rotational axis direction of the surface layer of the fixing rotor can be measured from the ratio of the shrinkage length at the start and end points of the TMA curve obtained by increasing the temperature from 25°C to 250°C at a rate of 10°C / min, holding the temperature for 5 minutes, and then decreasing the temperature from 250°C to 25°C at a rate of 10°C / min, as shown below, to the initial value at 25°C.

[0124] First, the surface layer is separated from the fixing rotor. Specifically, the surface layer is peeled off from the substrate together with the elastic layer, and the elastic layer bonded to the surface layer is dissolved in a solvent to separate only the surface layer. After that, the surface layer is cut into strips measuring 16 mm in the axial direction of the fixing rotor and 6 mm in the circumferential direction, and the strips are cut into strips. It was simple.

[0125] Next, a sample was placed on a sample attachment using a thermomechanical analyzer (TMA), and measurements were performed under the following conditions.

[0126] Apparatus: Thermomechanical analyzer TMA / SDTA2+ (trade name, manufactured by Mettler-Toledo) Load: 25mN Temperature: 25°C to 250°C at 10°C / min, then hold for 5 minutes, then cool from 250°C to 25°C at 10°C / min

[0127] The length of the fixing rotor in the axial direction at a temperature of 25°C during measurement was defined as L1s, and the length after the temperature was increased from 25°C to 250°C at a rate of 10°C / min, held for 5 minutes, and then decreased from 250°C to 25°C at a rate of 10°C / min was defined as L2s. The internal stress B [%] of the surface layer was calculated using the following formula (i): B=(L2s-L1s) / L1s×100 (i)

[0128] When the temperature is increased from 25°C to 250°C at a rate of 10°C / min, held at that temperature for 5 minutes, and then decreased from 250°C to 25°C at a rate of 10°C / min, the internal stress is relaxed and the surface layer shrinks. This difference can be calculated using equation (i). In other words, the double-headed arrow in Figure 8A indicates the internal stress in the surface layer. When used as a fixing belt, the surface layer and elastic layer are bonded together by an adhesive layer, so even if the temperature is raised from 25°C to 250°C at a rate of 10°C / min, held for 5 minutes, and then lowered from 250°C to 25°C at a rate of 10°C / min, the adhesion between the elastic layer and the surface layer prevents the surface layer from freely expanding and contracting. For this reason, the surface layer is isolated from the elastic layer in this measurement.

[0129] Examples of the results of the linear expansion coefficients of the elastic layer and surface layer of the present disclosure are shown in Figures 8A to 8C. In Figure 8B, it was confirmed that the elastic layer was subjected to an electric field orientation treatment, which oriented and aligned the filler in the thickness direction, thereby increasing the linear expansion coefficient in the rotation axis direction of the fixing rotor. A similar trend was also confirmed in the circumferential direction. Furthermore, in Figure 8C, for the surface layer, by controlling the heating treatment and cooling rate on the elastic layer, which has a large linear expansion coefficient in the rotation axis direction and circumferential direction of the fixing rotor, crystal parts are formed in a state where stress is applied three-dimensionally in the rotation axis direction and circumferential direction of the fixing rotor, and by controlling the cooling rate, the crystal parts are further increased, and the linear expansion coefficient of the fixing rotor increases. The internal stress B in the direction of the body's rotation axis is reduced.

[0130] (3-4) Method for measuring the amount of heat absorbed by the surface First, the surface layer was isolated from the fixing rotor. Specifically, the surface layer was peeled off from the substrate together with the elastic layer, and the elastic layer adhered to the surface layer was dissolved in a solvent to isolate only the surface layer.

[0131] The endothermic peak temperature and endothermic amount were measured using a differential scanning calorimeter (product name: Q2000, TA In Measurements were performed using a thermocouple (manufactured by Instruments). The melting points of indium and zinc were used for temperature correction of the detector, and the heat of fusion of indium was used for heat correction. Specifically, 4 mg of the surface layer was precisely weighed and placed in an aluminum pan. An empty aluminum pan was used as a reference, and measurements were performed at a temperature rise rate of 20°C / min within the measurement range of 25°C to 400°C. The temperature was raised to 400°C once and held for 5 minutes, and then lowered 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 was taken as the endothermic amount.

[0132] The linear expansion coefficient, linear expansion coefficient, and heat absorption rate of the surface layer are average values ​​measured at five or more points on the surface layer at equal intervals from the center of the belt in the circumferential direction. Similarly, the linear expansion coefficient and linear expansion coefficient of the elastic layer are average values ​​measured at five or more points on the elastic layer at equal intervals from the center of the belt in the circumferential direction.

[0133] (4) Actual machine evaluation (paper passing wrinkle resistance, gloss unevenness) (Evaluation method) Next, the evaluation method in this example will be described.

[0134] (Evaluation 1: Paper passing wrinkle resistance) The manufactured fixing rotor was used to perform evaluation using the thermal fixing device shown in Figure 2. The evaluation conditions were as follows. Test environment: room temperature 23°C, humidity 50% Process speed: 200 mm / sec Print speed: 30 pages / minute Paper passing conditions: Grid image on GF-C081 (manufactured by Nippon Paper Industries Co., Ltd., 81g paper, A4 size) was formed and continuously passed through. Mondi Color Copy (Mondi Co., Ltd., 250g paper) for every 100,000 sheets A4 size paper (SRA3 size) was passed through the printer, and the edges of the paper passing area were visually checked for scratches caused by wrinkles in the fixing rotor.If scratches were found, the printer was deemed to have reached the endurance life, and the printer was evaluated according to the following criteria.

[0135] (Evaluation criteria) Rank A: No scratches caused by wrinkles after 400,000 sheets Rank B: Scratches caused by wrinkles occur after 400,000 sheets Rank C: Scratches caused by wrinkles occur after 300,000 sheets Rank D: Scratches caused by wrinkles appear within 200,000 sheets

[0136] (Rating 2: Gloss unevenness rating) The manufactured fixing rotor was used to perform evaluation using the thermal fixing device shown in Figure 2. The evaluation conditions were as follows. Test environment: room temperature 25°C, humidity 50% Process speed: 200mm / sec Print speed: 30 pages / minute Paper conditions: Vitality (Xerox, 75g paper, A4 size) with 0.5g black toner. 4 mg / cm 3The level of gloss unevenness was visually confirmed and evaluated according to the following criteria.

[0137] (Evaluation criteria) A: Toner image gloss variations caused by paper irregularities are less visible B: Toner image gloss unevenness caused by paper unevenness is slightly visible C: Toner image gloss unevenness caused by paper unevenness is noticeable D: Toner image gloss unevenness caused by paper unevenness is particularly noticeable

[0138] In the following examples and comparative examples, elastic layers prepared in the same manner as elastic layer 1 in Example 1 were used in the combinations shown in Table 2, except that the filler type, filler addition amount, and electric field orientation treatment time were set as shown in Table 1. Table 1 shows the linear expansion coefficients of the elastic layers 1 to 4 in the rotation axis direction and circumferential direction of the fixing rotor, and the orientation and arrangement state of the filler. Hereinafter, the term "longitudinal direction" in the tables refers to the direction of the rotation axis of the fixing rotor.

[0139] [Table 1] In Table 1, h-BN means boron nitride.

[0140] In Examples 2 to 11 and Comparative Examples 2 to 4, the surface layer type, stress application method, first-stage annealing temperature, and second-stage annealing temperature (when the second-stage annealing was not performed) were as shown in Table 2. A fixing rotor was produced in the same manner as in Example 1, except that the other conditions (denoted by "-") were changed. Alternatively, as a method for applying internal stress to the surface layer, the thermal expansion of the underlying elastic layer during the one-stage annealing treatment may be utilized instead of the fixed stretching method of Example 1, as described above. Stress was applied using the elastic layer and surface layer listed in Table 2. When fixed stretching was used, the PFA was stretched in the axial and circumferential directions by the values ​​listed in Table 2 over the entire axial or circumferential length of the fixing rotor before application of stress. When utilizing the thermal expansion of the underlying elastic layer, the amount of tension was calculated using the following formula, using the linear expansion coefficient listed in Table 1 and the one-stage annealing temperature listed in Table 2, and the result is listed in Table 2. (Amount of tension in the direction of rotation axis) = (Linear expansion coefficient in the direction of rotation axis) x ((Temperature during first-stage annealing treatment) - 25°C) (Amount of tension in the circumferential direction) = (Coefficient of linear expansion in the circumferential direction) × ((Temperature during first-stage annealing treatment) - 25℃)

[0141] <Comparative Example 1> As shown in Table 2, a fixing belt was produced in the same manner as in Example 1 using AP-231SH (trade name, manufactured by Daikin Industries, Ltd.) and elastic layer 2, up to (2) the production of the fixing belt (without performing (3) the stress application to the surface layer, the stress application and the melting process of the fluororesin tube).

[0142] [Table 2]

[0143] The results of these evaluations are summarized in Table 3. [Table 3]

[0144] As shown in this example, the fixing rotating body according to the present disclosure can simultaneously suppress wrinkles and gloss unevenness.

[0145] The present disclosure relates to the following configurations. (Configuration 1) A fixing rotor, The fixing rotor comprises at least a base layer having an endless shape; an elastic layer on the outer peripheral surface side of the base layer; a surface layer fixed to the outer peripheral surface side of the elastic layer via an adhesive layer, When the length of a measurement sample taken from the surface layer in the direction of the rotation axis of the fixing rotor at 25°C is defined as L1s, and the measurement sample is pulled in the direction of the rotation axis of the fixing rotor with a load of 25 mN while being heated from 25°C to 250°C at a heating rate of 10°C / min, held at that temperature for 5 minutes, and then cooled from 250°C to 25°C at a cooling rate of 10°C / min, the length when the result is defined as L2s, the internal stress B represented by the following formula (i) is -3.0% or less, B(%)=(L2s-L1s) / L1s×100 (i) A fixing rotating body characterized by the above. (Configuration 2) the elastic layer contains silicone rubber, The surface layer contains a fluororesin. The fixing rotating member according to configuration 1. (Configuration 3) The fixing rotating body according to configuration 1 or 2, wherein when a measurement sample taken from the surface layer is subjected to calorimetry using a differential scanning calorimeter (DSC) by heating the measurement sample from 25°C to 400°C at a heating rate of 20°C / min, the amount of heat absorbed during the heating process is 21 J / g or more. (Configuration 4) When the measurement sample taken from the surface layer was subjected to calorimetry using a differential scanning calorimeter (DSC) by sequentially performing the following steps (1) and (2), Step (1): A temperature-raising step of heating the measurement sample from 25°C to 400°C at a temperature-raising rate of 20°C / min; Step (2): A temperature-reducing step of cooling the measurement sample heated to a temperature of 400°C in Step (1) to a temperature of 25°C at a temperature-reducing rate of 20°C / min; 4. The fixing rotatable member according to any one of configurations 1 to 3, wherein at least two endothermic peaks are present in the first DSC chart obtained in step (1). (Configuration 5) 5. The fixing rotating member according to any one of configurations 1 to 4, wherein the internal stress B is −5.0% or more. (Configuration 6) When the length of a measurement sample taken from the elastic layer in the direction of the rotation axis of the fixing rotor at 100°C during the temperature rise process is defined as L1e, the measurement sample is pulled in the direction of the rotation axis of the fixing rotor with a load of 25 mN while being heated from 25°C to 250°C at a temperature rise rate of 10°C / min, held for 5 minutes, and then cooled from 250°C to 25°C at a temperature drop rate of 10°C / min, and the length at 200°C during the temperature drop process is defined as L2e, the linear expansion coefficient A in the direction of the rotation axis of the fixing rotor, which is represented by the following formula (ii), is 0.0175% / °C or more, A(% / ℃)=(L2e-L1e) / L1e×100 / (200-100) ···(ii) The circumferential length of the measurement sample at 100°C is L3e, and the measurement sample is pulled in the circumferential direction with a load of 25 mN, and then heated from 25°C to 250°C at a heating rate of 10°C / min. The test piece is held for 5 minutes, and then cooled from 250°C to 25°C at a cooling rate of 10°C / min. When the length at 200°C during the cooling process is defined as L4e, the linear expansion coefficient A2 in the circumferential direction represented by the following formula (iii) is 0.0175% / °C or more. A2(% / ℃)=(L4e-L3e) / L3e×100 / (200-100) ···(iii) 6. The fixing rotating member according to any one of configurations 1 to 5. (Configuration 7) the elastic layer includes rubber and a thermally conductive filler dispersed in the rubber, In a total of ten binarized images, including a first binarized image of 150 μm×100 μm size at five locations on a first cross section of the elastic layer in the thickness-circumferential direction and a second binarized image of 150 μm×100 μm size at five locations on a second cross section of the elastic layer in the thickness-rotation axis direction, the average area ratio of the thermally conductive filler is 27 to 45%, the average degree of orientation f of the thermally conductive filler is 0.10 to 0.50; 7. The fixing rotator according to any one of configurations 1 to 6, wherein the thermally conductive filler has an average arrangement angle Φ of 28 to 90°. (Configuration 8) 8. The fixing rotator according to any one of configurations 1 to 7, wherein the base layer contains at least one selected from the group consisting of nickel, copper, iron, and aluminum. (Configuration 9) A thermal fixing device having a heating member and a pressure member arranged opposite the heating member, wherein at least one of the heating member and the pressure member is the fixing rotor described in any one of Configurations 1 to 8. (Configuration 10) An electrophotographic image forming apparatus including a thermal fixing device, the thermal fixing device has a heating member and a pressure member disposed opposite the heating member, 9. An electrophotographic image forming apparatus, wherein at least one of the heating member and the pressure member is the fixing rotatable member according to any one of Configurations 1 to 8. [Explanation of symbols]

[0146] 10: Image forming unit, 11: Photosensitive drum, 12: Charger, 13: Laser scanner, 14: Developer, 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 belt, 41a: Surface layer, 41b: Base layer, 41c: Elastic layer, 41d: Inner layer, 43: Heating element, 44: Pressure roller, 45: Contact thermistor, 46: Heater holder 101: Core, 200: Corona charger, 201: Front block, 202: Back block 203, 204: Shield, 205: Discharge wire, 206: Grid 401-1: 1st cross section, 401-2: 2nd cross section P: Sheet, T: Toner image

Claims

1. A fixing rotor, The fixing rotor comprises at least a base layer having an endless shape; an elastic layer on the outer peripheral surface side of the base layer; a surface layer fixed to the outer peripheral surface side of the elastic layer via an adhesive layer, When the length of a measurement sample taken from the surface layer in the direction of the rotation axis of the fixing rotor at 25°C is defined as L1s, the measurement sample is pulled in the direction of the rotation axis of the fixing rotor with a load of 25 mN while being heated from 25°C to 250°C at a heating rate of 10°C / min, held for 5 minutes, and then cooled from 250°C to 25°C at a cooling rate of 10°C / min, the length when the result is defined as L2s, an internal stress B represented by the following formula (i) is -3.0% or less: B (%)=(L2s-L1s) / L1s×100...(i) A fixing rotating body characterized by the above.

2. the elastic layer contains silicone rubber, The surface layer contains a fluororesin. The fixing rotor according to claim 1 .

3. 2. The fixing rotating body according to claim 1, wherein when a measurement sample taken from the surface layer is subjected to calorimetry using a differential scanning calorimeter (DSC) by heating the measurement sample from 25°C to 400°C at a heating rate of 20°C / min, the amount of heat absorbed during the heating process is 21 J / g or more.

4. When the measurement sample taken from the surface layer was subjected to calorimetry using a differential scanning calorimeter (DSC) by sequentially carrying out the following steps (1) and (2), Step (1): A temperature-raising step of heating the measurement sample from 25°C to 400°C at a temperature-raising rate of 20°C / min; Step (2): A temperature-reducing step of cooling the measurement sample heated to a temperature of 400°C in Step (1) to a temperature of 25°C at a temperature-reducing rate of 20°C / min; 2. The fixing rotor according to claim 1, wherein at least two endothermic peaks are present in the first DSC chart obtained in step (1).

5. 2. The fixing rotating member according to claim 1, wherein the internal stress B is −5.0% or more.

6. The length of a measurement sample taken from the elastic layer in the direction of the rotation axis of the fixing rotor at 100°C during the temperature rise process is defined as L1e, and the measurement sample is pulled in the direction of the rotation axis of the fixing rotor with a load of 25 mN while being heated from 25°C to 250°C at a temperature rise rate of 10°C / min, held for 5 minutes, and then cooled from 250°C to 25°C at a temperature drop rate of 10°C / min, and the length at 200°C during the temperature drop process is defined as L2e. The linear expansion coefficient A in the direction of the rotation axis of the fixing rotor, which is represented by the following formula (ii), is 0.0175% / °C or more, A (% / ℃)=(L2e-L1e) / L1e×100 / (200-100)...(ii) The circumferential length of the measurement sample at 100°C is defined as L3e, and the measurement sample is pulled in the circumferential direction with a load of 25 mN while being heated from 25°C to 250°C at a heating rate of 10°C / min, held for 5 minutes, and then cooled from 250°C to 25°C at a cooling rate of 10°C / min, and the length at 200°C during the cooling process is defined as L4e. The circumferential linear expansion coefficient A2, which is represented by the following formula (iii), is 0.0175% / °C or more. A2 (% / ℃) = (L4e-L3e) / L3e×100 / (200-100) ... (iii) The fixing rotor according to claim 1 .

7. the elastic layer includes rubber and a thermally conductive filler dispersed in the rubber, In a total of ten binarized images, including a first binarized image of 150 μm×100 μm in size at five locations on a first cross section in the thickness-circumferential direction of the elastic layer, and a second binarized image of 150 μm×100 μm in size at five locations on a second cross section in the thickness-rotation axis direction of the elastic layer, the average area ratio of the thermally conductive filler is 27 to 45%; the average degree of orientation f of the thermally conductive filler is 0.10 to 0.50; 2. The fixing rotating member according to claim 1, wherein the thermally conductive filler has an average arrangement angle Φ of 28 to 90°.

8. 2. The fixing rotor according to claim 1, wherein the base layer contains at least one selected from the group consisting of nickel, copper, iron, and aluminum.

9. A thermal fixing device having a heating member and a pressure member arranged opposite the heating member, wherein at least one of the heating member and the pressure member is the fixing rotating body according to any one of claims 1 to 8.

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

Images