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

Abstract

To provide a rotating body for fixing that can satisfy all of prevention of wrinkles in a surface layer, prevention of uneven glossiness of an image, and fixability in continuous use.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 substrate, and a surface layer fixed to an outer peripheral surface of the elastic layer with an adhesive layer therebetween. The thermal conductivity in a thickness direction of the elastic layer is 1.0 W / mK or more. When a coefficient of linear expansion at a temperature of 200°C, which is measured while pulling the elastic layer removed from the rotating body for fixing in a rotation axis direction of the rotating body for fixing, is defined as A, and a coefficient of linear expansion at a temperature of 200°C, which is measured while pulling the surface layer removed from the rotating body for fixing in the rotation axis direction of the rotating body for fixing, is defined as B, A is larger than B and A-B is 2.0% or more.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] Fixing members used in the heat fixing devices of electrophotographic image forming apparatuses (hereinafter also referred to as "image forming apparatuses") such as printers, copiers, and facsimiles include film-shaped or roller-shaped fixing rotors. For example, known fixing members include a film- or roller-shaped substrate made of heat-resistant resin or metal, on which an elastic layer made of heat-resistant rubber or the like is optionally formed, 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 reducing waste by extending the lifespan of fixing members. One of the challenges in extending the lifespan of materials used in fixing members is "surface wrinkles." This occurs when the fixing member is used over a long period of time, and the strength of the surface layer material gradually decreases due to repeated heat cycles of temperature increase and decrease.

[0004] For example, when a fluororesin tube material is used as the surface layer of a fixing member, the fluororesin tube is tightly stretched to cover the surface of the fixing member 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" occur on the surface layer of the fixing member.

[0005] If the wrinkles extend to the area where the toner image is formed, the wrinkles will be transferred onto the fixed toner image, causing an image defect and requiring replacement of the fixing member. As a method for solving this problem, for example, Patent Documents 1 to 3 disclose a treatment for pre-heat shrinking a fluororesin tube used in a fixing member. By imparting heat shrinkage, the linear expansion coefficient during heating is reduced, and the amount of thermal expansion and contraction during a heat cycle is also reduced, which reduces the 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 recognized that the inventions of Patent Documents 1 to 3 have the following problems. In the method of imparting heat shrinkage to fluororesin tubes manufactured by extrusion molding, the method of imparting heat shrinkage after extrusion is often used, but this increases the number of tube manufacturing steps and increases manufacturing costs. In addition, only fluororesin materials that can be imparted with heat shrinkage can be used. This places restrictions on the selection of materials.

[0008] Furthermore, when a heat-shrinkable fluororesin tube is used, the heat shrinkage of the tube during manufacturing tightens the elastic layer, increasing the apparent hardness of the fixing member, which reduces the ability of the fixing member to conform to the unevenness of the media, potentially resulting in gloss unevenness and other degradation of image quality. 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.

[0009] As described above, it is difficult to satisfy all of the requirements for suppressing wrinkles on the surface layer, suppressing uneven gloss in the image, and achieving good fixability. This disclosure relates to a fixing rotor that can satisfy all of the requirements for suppressing wrinkles on the surface layer during continuous use, suppressing uneven gloss in the image, and achieving good fixability. This disclosure also relates to a heat fixing device and an electrophotographic image forming apparatus that include the fixing rotor. [Means for solving the problem]

[0010] 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 substrate; a surface layer fixed to the outer peripheral surface side of the elastic layer via an adhesive layer, The thermal conductivity of the elastic layer in the thickness direction is 1.0 W / mK or more, The elastic layer removed from the fixing rotor is pulled in the direction of the rotation axis of the fixing rotor with a load of 25 mN while the temperature is increased from 25°C to 250°C at a temperature increase rate of 10°C / min, and in the TMA curve where the horizontal axis is temperature and the vertical axis is linear expansion coefficient, the linear expansion coefficient at a temperature of 200°C is defined as A, The surface layer removed from the fixing rotor was 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, and in the TMA curve obtained, the horizontal axis is temperature and the vertical axis is linear expansion coefficient, when the linear expansion coefficient at a temperature of 200°C is designated as B, The present invention relates to a fixing rotating body in which A>B and AB is 2.0% or more.

[0011] The present disclosure provides a heat fixing device having a heating member and a pressure member disposed opposite the heating member, The present invention relates to a heat fixing device, wherein at least one of the heating member and the pressure member is the fixing rotor.

[0012] The present disclosure provides an electrophotographic image forming apparatus including a heat fixing device, the heat fixing device has a heating member and a pressure member disposed opposite the heating member, The present invention relates to an electrophotographic image forming apparatus, wherein at least one of the heating member and the pressure member is the fixing rotor. [Effects of the Invention]

[0013] According to the present disclosure, a fixing rotator is provided that can suppress wrinkles in the surface layer during continuous use, suppress uneven gloss in images, and provide good fixability. Also, according to the present disclosure, a heat fixing device and an electrophotographic image forming apparatus that include the fixing rotator are provided. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of a fixing device according to the present embodiment. [Figure 3] FIG. 2 is a schematic diagram of a fixing belt in the present embodiment. [Figure 4] 1A and 1B are a top view and a cross-sectional view 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 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 this example. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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. Furthermore, when a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined. 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.

[0016] Next, specific examples (examples) of embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited to the following examples. 1 is a cross-sectional view of a color electrophotographic printer, which is an example of an image forming apparatus according to this embodiment, taken along the sheet conveying direction. In this embodiment, the color electrophotographic printer is simply referred to as a "printer."

[0017] The printer shown in FIG. 1 includes image forming units 10 for the colors Y (yellow), M (magenta), C (cyan), and Bk (black). Photosensitive drum 11 is pre-charged by charger 12. A latent image is then formed on photosensitive drum 11 by laser scanner 13. The latent image is then converted into a toner image by developer 14. The toner image on photosensitive drum 11 is sequentially transferred by primary transfer blade 17 to an image carrier, such as intermediate transfer film 31. After transfer, any toner remaining on photosensitive drum 11 is removed by cleaner 15. As a result, the surface of photosensitive drum 11 becomes clean and is ready for the next image formation.

[0018] 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 feeds the sheet between the intermediate transfer film 31 and the secondary transfer roller 35 in synchronization with the toner image on the intermediate transfer film 31. The color toner image on the intermediate transfer film is transferred onto the sheet P by a transfer body, such as the secondary transfer roller 35. The toner image on the sheet is then fixed to the sheet by applying heat and pressure to the sheet by the heat fixing device 40.

[0019] The image forming apparatus is equipped with a heat fixing device. The heat fixing device will be described. Figure 2 shows a schematic diagram of heat fixing device 40, and a belt (film) heating type heating device (tensionless type) was used.

[0020] The heater 43 is a ceramic heater (hereinafter referred to as the heater) that serves 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. When electricity is applied to the heat-generating resistor layer, the heater has a low heat capacity and its temperature rises sharply as a whole. The fixing rotor may be a pressure member such as a pressure belt or a pressure roller. In a heat fixing device, at least one of the heating member and the pressure member may be the fixing rotor of the present disclosure.

[0021] As an example of a fixing rotating body, reference numeral 41 denotes a cylindrical (endless) heat-resistant fixing belt serving as a heating member for transmitting heat, which is loosely fitted onto the outside of a support member including the heater 43. The fixing belt 41 in this embodiment is as shown in Fig. 3, and is a fixing belt having a composite structure of, for example, a surface layer 41a, an adhesive layer 41b, an elastic layer 41c, and a base layer 41d.

[0022] The heat-fixing device has a heating member 41 and a pressure member 44 disposed opposite the heating member. Reference numeral 44 denotes a heat-resistant elastic pressure roller serving as the pressure member. It consists of a core and an elastic layer made of heat-resistant rubber such as silicone rubber or fluororubber, or a silicone rubber foam. Both ends of the core are rotatably supported by bearings. The fixing belt 41 and heater 43 are disposed above the pressure roller 44, parallel to the pressure roller 44 with respect to the heater 43 side, and are pressed by a pressing member (not shown). This causes the lower surface of the heater 43 to be pressed against the upper surface of the pressure roller 44 via the fixing belt 41 against the elasticity of the roller's elastic layer, forming a fixing nip T of a predetermined width as a heating section.

[0023] 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). A rotational force acts on the cylindrical fixing belt 41 due to the frictional force generated between the pressure roller 44 and the fixing belt 41 at the fixing nip T caused by the rotation of the pressure roller 44. The fixing belt 41 then slides in close contact with the downward surface of the heater 43 and rotates clockwise as indicated by the arrow. The support member also serves as a rotation guide member for the cylindrical fixing belt 41.

[0024] 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 recording material 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 recording material P then comes into close contact with the outer surface of the fixing belt 41, and the recording material P is sandwiched and transported to the fixing nip together with the fixing belt 41. During this sandwiching and transport process, the recording material 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 recording material P is heated and pressurized onto the recording material P, melting and fixing it. Having passed through the fixing nip, the recording material P separates from the surface of the fixing belt 41 and is then discharged and transported.

[0025] Reference numeral 45 denotes a contact thermometer (thermistor) that measures the temperature of the fixing belt 41 heated by the heater 43 and passes the detection result to a temperature control means (not shown). Reference numeral 46 denotes a heater holder, which is a member that holds the heater 43 that has been heated to a high temperature.

[0026] Next, the fixing rotor will be described. Examples of the fixing rotor include a fixing film, a fixing belt, and a fixing roller. The fixing rotor of the present disclosure includes at least an endless base layer, an elastic layer, and a surface layer, in this order. Other layers may be provided between each layer as needed. The fixing rotor includes at least an endless base layer, an elastic layer on the outer peripheral surface side of the base layer, and a surface layer fixed to the outer peripheral surface side of the elastic layer via an adhesive layer. Below, a fixing belt will be described in detail as an example of the fixing rotor.

[0027] The fixing belt 41 is as shown in Fig. 3. The fixing belt has a base layer 41d, an elastic layer 41c covering the outer surface of the base layer, and a surface layer 41a covering the surface of the elastic layer opposite to the side facing the base layer. The surface layer 41a is adhered to the elastic layer 41c by an adhesive layer 41b on the surface opposite to the side facing the base layer.

[0028] In the present disclosure, the linear expansion coefficients of the elastic layer and the surface layer have the following relationship. The elastic layer removed from the fixing rotor is pulled in the direction of the rotation axis of the fixing rotor with a load of 25 mN while the temperature is raised from 25°C to 250°C at a heating rate of 10°C / min. In the TMA curve, the horizontal axis is temperature and the vertical axis is linear expansion coefficient, and the linear expansion coefficient at a temperature of 200°C is defined as A. The surface layer removed from the fixing rotor is pulled in the direction of the rotation axis of the fixing rotor with a load of 25 mN while the temperature is increased from 25°C to 250°C at a rate of 10°C / min. In the TMA curve, the horizontal axis is temperature and the vertical axis is linear expansion coefficient. The linear expansion coefficient at a temperature of 200°C is defined as B.

[0029] In this case, it is satisfied that A>B and AB is 2.0% or more. When these conditions are satisfied, it is possible to suppress both wrinkles in the surface layer and uneven gloss of the image. The inventors believe that the reason for this is as follows.

[0030] First, when the linear expansion coefficient of the elastic layer is greater than that of the surface layer (A > B), tension is applied to the surface layer in the direction of the rotation axis, and it is believed that the greater the tension (AB) applied to the surface layer, the more tension can be maintained until the end of the durability test of a fixing member that is repeatedly bent, and the more wrinkles can be suppressed. On the other hand, from the perspective of gloss unevenness, gloss unevenness is caused by uneven toner melting, which depends on the microscopic ability to conform to paper irregularities, so it is preferable that the tension (AB) of the surface layer, which affects microscopic conformity, is small. The inventors believe that the range in which both the suppression of wrinkles and gloss unevenness are achieved is when A > B and AB is 2.0% or more.

[0031] The reason why a temperature of 200° C. was selected for measuring the linear expansion coefficient is that this temperature is close to the actual operating temperature that the surface layer reaches when used as a fixing device. Also, AB is preferably 2.0 to 7.0%, more preferably 2.0 to 5.2%, and even more preferably 2.1 to 5.0%.

[0032] Furthermore, the thermal conductivity of the elastic layer in the fixing rotor must be 1.0 W / mK or higher in the thickness direction. Meeting this thermal conductivity further improves fixability. Therefore, by ensuring that the above-mentioned A and B satisfy a specific relationship and setting the thermal conductivity of the elastic layer in the thickness direction within a specific range, it is possible to suppress wrinkles in the surface layer, suppress uneven gloss in the image, and achieve good fixability. The thermal conductivity of the elastic layer in the thickness direction is preferably 1.0 to 3.0 W / mK, more preferably 1.1 to 2.0 W / mK, and even more preferably 1.2 to 1.6 W / mK.

[0033] (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.

[0034] The outer surface of the base layer 41d may be subjected to a surface treatment to provide adhesion to the elastic layer. The surface treatment may be one or a combination of physical treatments such as blasting, lapping, and polishing, and chemical treatments such as oxidation, coupling agent treatment, and primer treatment. It is possible to use.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] (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. The elastic layer contains rubber as a matrix and a thermally conductive filler dispersed in the rubber. More specifically, for example, the elastic layer contains rubber and a thermally conductive filler, and is composed of a cured product obtained by curing a composition that contains at least rubber raw materials (base polymer, crosslinking agent, etc.) and a thermally conductive filler.

[0039] The rubber is preferably silicone rubber. A composition containing at least rubber raw materials (base polymer, crosslinking agent, etc.) and thermally conductive particles 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.

[0040] The matrix is ​​responsible for providing elasticity to the elastic layer. From the viewpoint of providing the above-described functions of the elastic layer, the matrix preferably contains silicone rubber. Silicone rubber is preferable because it has high heat resistance, allowing it to maintain flexibility even in environments where temperatures reach as high as about 240°C in the non-paper-passing area. For example, a cured product of an addition-curing liquid silicone rubber composition, which will be described later, can be used as the silicone rubber.

[0041] 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.

[0042] 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. The linear organopolysiloxane having an unsaturated aliphatic group is, for example, an organopolysiloxane represented by the following formula (1): and compounds represented by formula (2). [ka]

[0043] In formula (1), m 1 represents an integer of 0 or more (preferably 500 to 1100), and n1 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. [ka]

[0044] 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.

[0045] 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: 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).

[0046] 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. 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, the following are preferred because they are easy to synthesize and handle, inexpensive, and easily undergo crosslinking reactions: Since it is done, R 2 and R 4 is preferably a vinyl group.

[0047] From the viewpoint of moldability, the viscosity of component (a) is 1000mm 2 / s or more 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 blend amount of component (a) is preferably 55% by volume or more based on the liquid 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.

[0048] 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.

[0049] Specific examples of component (b) include the linear organopolysiloxane shown in formula (3) below and the cyclic organopolysiloxane shown in formula (4) below. [ka]

[0050] In 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. [ka] In formula (4), m 3 represents an integer of 0 or more (preferably 10 to 30), and n 4 is 3 or more (preferably Preferably, R is an integer of 5 to 20. 6 each independently represents a monovalent unsubstituted or substituted hydrocarbon group that does not contain an unsaturated aliphatic group.

[0051] 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.

[0052] 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.

[0053] 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. 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.

[0054] In a TMA curve, where the horizontal axis is temperature and the vertical axis is linear expansion coefficient, obtained by heating the elastic layer from 25°C to 250°C at a heating rate of 10°C / min while pulling the elastic layer with a load of 25 mN in the direction of the rotation axis of the fixing rotor, A is the linear expansion coefficient at a temperature of 200°C. The linear expansion coefficient A is, for example, 2.7 to 6.5%, and preferably 3.0 to 5.0%. If A is 3.0% or more, crystal formation can be performed while applying stress to the surface layer in the direction of the rotation axis of the fixing rotor in the surface layer processing step described below, thereby further reducing the linear expansion coefficient of the surface layer. If A is 6.0% or less, the linear expansion coefficient of the surface layer can be reduced, and gloss unevenness can be further suppressed.

[0055] The linear expansion coefficient of the elastic layer can be controlled by the ratio of silicone rubber as a matrix, which has a high linear expansion coefficient as a single substance, to the thermally conductive filler, which has a low linear expansion coefficient as a single substance. Increasing the silicone rubber ratio to increase the linear expansion coefficient to 3.0% or more may result in a decrease in thermal conductivity. Therefore, it is preferable to achieve thermal conductivity with a small amount of filler by orienting the thermally conductive filler in the thickness direction using the electric field application process described below.

[0056] Furthermore, compared to a configuration in which the filler is randomly arranged, by aligning the filler in the thickness direction, the filler becomes relatively sparse in the direction of the rotation axis of the fixing rotor facing the thickness direction, which reduces the influence of the inorganic filler with a low linear expansion coefficient, and as a result, the linear expansion coefficient of the entire elastic layer in the direction of the rotation axis of the fixing rotor can be maintained high. Therefore, the electric field application process makes it easy to satisfy the thermal conductivity of the elastic layer in the thickness direction while satisfying the above-mentioned relationship between A and B.

[0057] It is preferable to electrically charge the surface of the elastic layer before curing the rubber to orient the filler. Therefore, the rubber is preferably electrically insulating or semiconductive, and for example, a cured silicone polymer can be used as described below.

[0058] The filler may be surface-treated from the viewpoint of affinity to silicone and electrical resistance. Specifically, fillers such as alumina, silica, and magnesium oxide having active groups such as hydroxyl groups on the surface may be surface-treated with a silane coupling agent, hexamethyldisilazane, or the like. Metal fillers may be surface-treated by forming an oxide film. 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. 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.

[0059] (2-2) Confirmation of the orientation and arrangement of the thermally conductive filler in the elastic layer In the electric field application step described later, the thermally conductive filler can be oriented in the thickness direction of the elastic layer. By orienting the filler in the thickness direction, it is easy to achieve thermal conductivity with a small amount of filler. Also, 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 direction of the rotation axis of the fixing rotor facing the thickness direction, which reduces the effect of the inorganic filler with a low linear expansion coefficient. As a result, the linear expansion coefficient of the entire elastic layer in the direction of the rotation axis of the fixing rotor can be maintained high.

[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 rotating body is a fixing belt 41 as shown in Fig. 5A, ten samples 401 each measuring 5 mm in length, 5 mm in width, and the entire thickness of the fixing belt are taken from ten locations in the central portion of the fixing belt in the direction of its rotation axis, one at equal intervals around the circumference, as shown in Fig. 5B.

[0061] Of the ten samples obtained, five samples were polished using an ion beam to the circumferential cross section of the fixing belt, i.e., a cross section including a first cross section 401-1 in the thickness-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 thickness-rotation axis direction of the elastic layer, was polished using an ion beam. A cross-section polisher was used for polishing the cross section using an ion beam. Polishing the cross section using an ion beam can prevent filler from falling off the sample or abrasive contamination, and can also produce a cross section with fewer polishing marks.

[0062] 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, the polished cross sections were observed using a laser microscope (OLS3000, manufactured by Olympus) or a scanning electron microscope (SEM) (S4700, manufactured by 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.

[0063] Furthermore, by performing two-dimensional Fourier transform analysis on this filler image, an elliptical plot showing the direction and extent of filler alignment can be obtained (Fig. 6C and Fig. 6D, respectively). The two-dimensional Fourier transform itself has a peak in the direction perpendicular to the periodicity of the binarized image, so the elliptical plot The plot is the result of a two-dimensional Fourier transform with a phase shift of 90°. The arrangement angle Φ can be calculated from the angle formed by the semi-major axis of this ellipse plot, and the filler arrangement degree f, defined as f=1-(y / x) when the semi-major axis is x and the semi-minor axis is y, can be calculated.

[0064] 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.

[0065] In this way, a total of ten binarized images are obtained: a first binarized image measuring 150 μm x 100 μm at five locations on the first cross section of the elastic layer in the thickness-circumferential direction, and a second binarized image measuring 150 μm x 100 μm at five locations on the second cross section of the elastic layer in the thickness-rotation axis direction. Then, the average area ratio of 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 in the binarized images. Each average value is calculated by averaging the values ​​at a total of ten locations.

[0066] The average degree of orientation f of the thermally conductive filler is preferably 0.10 to 0.50, and more preferably 0.13 to 0.35. 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.

[0067] 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, so they are synonymous in terms of 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.

[0068] 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.

[0069] (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.

[0070] 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 by a high-voltage power supply, the discharge wire 205 The surface of the uncured elastic layer 41c on the base layer as the member to be charged is charged.

[0071] 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.

[0072] To explain the manufacturing method of the fixing rotor of the above embodiment in detail, first, an elastic layer made of silicone rubber containing a thermally conductive filler is formed on a base layer. Next, as shown in FIG. 4A, corona chargers 200 are positioned adjacent to and facing the uncured elastic layer 41c of the fixing rotor 41 in the width direction. A voltage is applied to the grid 206 of the corona charger 2, and the fixing rotor 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 1 mm to 10 mm. By charging the surface of the elastic layer 41c in this manner, an electric field is generated within the elastic layer, orienting the thermally conductive filler. The elastic layer is then cured by heating or other means, thereby fixing the filler orientation.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] As shown in FIG. 7, the central part of the grid 206 in the short direction (the direction in which the shields 203 and 204 in FIG. 4B face each other) is mesh-shaped, and both ends in the short direction are beam parts with a width of 1.5±0.1 mm as shown in (6). The width of the through-holes in the grid 206 is 0.312±0.03 mm as shown in (1). The angle of the through-holes with respect to the long direction of the 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, there is a spacing between the mesh parts as shown in (5). To suppress the deflection of the grid 206, beams (4) each having a width of 0.1±0.03 mm are arranged in the longitudinal direction at intervals of 6.9±0.1 mm.

[0078] 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.

[0079] As shown in FIG. 7, this flat grid 206 is tensioned by tensioning sections disposed on the front block 201 and the rear block 202. Operating the knobs on the tensioning sections releases the support for the grid 206, allowing it to be easily attached and detached. Furthermore, a portion of the flat plate of the grid 206 near the tensioning section is bent, providing some flexibility. Therefore, even when the grid 206 is tensioned by 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, a flat grid with a honeycomb structure as disclosed in Japanese Patent Application Laid-Open No. 2005-338797 may also be used.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] (3) Adhesive layer The adhesive layer 41b 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. The addition-curing silicone rubber adhesive contains uncrosslinked silicone rubber components, and when heated, it bonds with the inner surface treatment layer of the surface layer and the uncrosslinked components of the elastic layer, thereby bonding the surface layer and the elastic layer.

[0084] The thickness of the adhesive layer is preferably 20 μm or less. By making it 20 μm or less, the thermal resistance of the fixing rotor can be set small, and heat from the inner surface side (substrate side) can be efficiently transmitted 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. It can be obtained.

[0085] (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). PFA is preferred in terms of releasability and rigidity. Commercially available PFAs 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, Inc.), which has a small spherulite size. The thickness of the surface layer 41a is preferably 100 μm or less, and more preferably 10 to 70 μm.

[0086] 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 having 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.

[0087] 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.

[0088] In the present disclosure, 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 heating rate of 10°C / min. In the TMA curve, the horizontal axis is temperature and the vertical axis is linear expansion coefficient, and the linear expansion coefficient at a temperature of 200°C is defined as B. B is, for example, -0.5 to 2.0%, and preferably 0 to 1.5%. If B is 1.5% or less, wrinkles in the surface layer after durable use are less likely to occur, and if B is 0% or more, gloss unevenness can be further suppressed.

[0089] The linear expansion coefficient B 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 B 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 further increase the crystalline portions. As a result, the linear expansion coefficient is easily reduced.

[0090] Furthermore, when a measurement sample taken from the surface layer 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. The following description will be given taking the case where the surface layer 41a is made of PFA as an example, but is not limited to this.

[0091] The heat absorption during the temperature rise process is the heat absorption due to the crystalline melting of PFA. The crystallinity of PFA can be calculated by dividing the heat absorption value by the heat of complete crystalline melting of PTFE (92.9 J / g). When the heat absorption value is 21 J / g or more, there are many crystalline parts, and the fixing circuit is The linear expansion coefficient of the rolling elements in the direction of the rotation axis can be reduced.

[0092] One method for achieving a heat absorption 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.

[0093] Although the specific method is not particularly limited, the following methods for heat treatment of the surface layer can be used.

[0094] To heat the entire fixing rotor, an upright cylindrical heating cylinder capable of heating up to 330°C or higher is used. A band heater equipped with a thermocouple is installed inside the heating cylinder to control the heating temperature of the fixing rotor. The heating temperature is preferably above the melting point of PFA and 350°C or lower. The heating time may be any time long enough to allow the surface layer to reach the desired temperature, and examples include 1 to 20 minutes, 1 to 10 minutes, and 2 to 5 minutes.

[0095] 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. [Example]

[0096] The present disclosure will be described in more detail below using examples.

[0097] (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.

[0098] Next, 160 parts by mass of metallic silicon (product name: #350, manufactured by Kinsei Matec Co., Ltd.) as component (d) thermally conductive filler was added to this Vi and mixed thoroughly to obtain mixture 1.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] (2) Fabrication of the fixing belt A stainless steel endless belt with an inner diameter of 24 mm, a width of 400 mm, and a thickness of 30 μm was prepared as the base layer. During the series of manufacturing processes, the endless belt was handled with a core inserted inside. 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.

[0103] 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 uncured elastic layer surface while the uncured endless belt was rotating at 100 rpm. The conditions were: current supplied to the corona charger's discharge wire: ±150 μA; grid electrode potential: ±300 V (Vp-p: 600 V); frequency: 0.025 Hz; charging time: 160 seconds; distance between the grid electrode and the belt: 3 mm. 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.

[0104] Next, an addition-cure 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 as an adhesive layer on the surface of the cured endless belt's elastic layer. Meanwhile, PFA (product name: AP-231SH; manufactured by Daikin Industries, Ltd.) was extruded to an inner diameter of 23 mm and a thickness of 20 μm to form a fluororesin tube with an etched inner surface as a surface layer. The fluororesin tube was then laminated onto the endless belt with the 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, thinning the thickness to 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.

[0105] The obtained endless belt was inserted into a heating cylinder with an inner diameter of φ42 mm and heated by a band heater inside the heating cylinder. The heating temperature at the end of the fixing rotor was set to 330°C, and the heating was controlled so that the actual temperature of the surface layer was equal to or higher than the melting temperature of PFA. The heating time was set to 3 minutes after the fixing belt was placed in the heating barrel, which was the time required for the actual temperature of the surface layer to reach the desired temperature. After 3 minutes had passed, the heating barrel was cooled to 200°C at a rate of 20°C / min, and then the fixing belt was taken out of 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.

[0106] (3) Evaluation of the characteristics of the elastic layer of the fixing belt (3-1) Thermal conductivity of the elastic layer in the thickness direction The thermal conductivity λ of the elastic layer in the thickness direction was calculated from the following formula. λ=α×C p ×ρ In the formula, λ is the thermal conductivity of the elastic layer in the thickness direction (W / (m K)), and α is the thermal diffusivity in the thickness direction (m 2 / s), C p is the specific heat at constant pressure (J / (kg·K)), and ρ is the density (kg / m 3 ) where the thermal diffusivity in the thickness direction α and the specific heat at constant pressure C p The values ​​of ρ and density were determined by the following method.

[0107] ·Thermal diffusivity α The thermal diffusivity α of the elastic layer in the thickness direction was measured at room temperature (25°C) using a cyclic heating method thermal property measurement device (trade name: FTC-1, manufactured by Advance Riko Co., Ltd.). Sample pieces with an area of ​​8 × 12 mm were cut from the elastic layer with a cutter to prepare five sample pieces in total, and the thickness of each sample piece was measured using a digital length measuring device (trade name: DIGIMICRO (registered trademark) MF-501). The measurement was carried out using a rat probe φ4 mm (manufactured by Nikon Corporation). Next, the measurement was carried out five times for each sample piece, and the average value (m 2 The measurement was carried out while applying pressure to the sample using a 1 kg weight. As a result, the thermal diffusivity α of the silicone rubber elastic layer in the thickness direction was 9.31 × 10 -7 m 2 / s.

[0108] Constant pressure specific heat C P The constant pressure specific heat of the elastic layer was measured using a differential scanning calorimeter (trade name: DSC823e, manufactured by Mettler-Toledo K.K.). Specifically, aluminum pans were used as the sample pan and the reference pan. First, as a blank measurement, both pans were empty and kept at a constant temperature of 15°C for 10 minutes. Then, the temperature was increased to 215°C at a rate of 10°C / min, and the temperature was kept constant at 215°C for another 10 minutes. Next, 10 mg of synthetic sapphire with a known low-pressure specific heat was used as a reference material, and measurements were performed using the same program. Next, a 10 mg measurement sample, the same amount as the synthetic sapphire reference material, was cut out from the elastic layer, set in a sample pan, and measured using the same program. These measurement results were analyzed using the specific heat analysis software attached to the differential scanning calorimeter, and the constant pressure specific heat at 25°C, C P was calculated. As a result, the specific heat at constant pressure of the silicone rubber elastic layer was found to be 1.05 J / (g·K).

[0109] ·Density ρ The density of the elastic layer was measured using a dry automatic density meter (product name: Accupyc 1330-01, manufactured by Shimadzu Corporation). 3 A sample cell was used, and a sample piece was cut out from the elastic layer so that it filled approximately 80% of the cell volume. The mass of this sample piece was measured and then placed in the sample cell. This sample cell was set in the measurement section of the device, and after gas replacement using helium as the measurement gas, the volume measurement was carried out 10 times. The density of the elastic layer was calculated from the mass of the sample piece and the measured volume for each measurement, and the average value was calculated. As a result, the density of the silicone rubber elastic layer was 1.53 g / cm 3 It was.

[0110] From the above, the unit converted specific heat of the elastic layer at constant pressure C p (J / (kg·K)) and density ρ(kg / m 3 ), and the measured thermal diffusivity α(m 2The thermal conductivity λ of the elastic layer in the thickness direction was calculated from the thermal conductivity (W / (m·K)).

[0111] (3-2) Linear expansion coefficient of the elastic layer in the direction of the rotation axis of the fixing rotor <Method for measuring thermal expansion coefficient> First, the elastic layer is separated from the fixing rotor. Specifically, the elastic layer can be separated by inserting a razor or similar into the substrate-elastic layer interface and the surface layer-elastic layer interface. The elastic layer is then cut into strips measuring 20 mm x 2 mm to serve as samples. The strips are cut so that the rotation axis direction is 20 mm.

[0112] Next, a sample was placed on a sample attachment using a thermomechanical analyzer (TMA), and measurements were performed under the following conditions. Apparatus: Thermomechanical analyzer TMA / SDTA2+ (trade name, manufactured by Mettler-Toledo) Load: 25mN Temperature: Raise from 25°C to 250°C at 10°C / min, hold for 5 minutes, then lower from 250°C to 25°C at 10°C / min The linear expansion coefficient A is expressed as follows: when the length of the fixing rotor in the direction of the rotation axis at a temperature of 25°C is expressed as L1e, and the length of the fixing rotor in the direction of the rotation axis at a temperature of 200°C is expressed as L2e. A=((L2e-L1e) / L1e)×100 It was calculated as:

[0113] (3-3) Linear expansion coefficient of the surface layer in the direction of the rotation axis of the fixing rotor First, the surface layer is isolated 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, allowing the surface layer to be isolated. The surface layer is then cut into strips measuring 20 mm x 2 mm to serve as samples. The strips are cut so that the rotation axis direction is 20 mm.

[0114] Next, a sample was placed on a sample attachment using a thermomechanical analyzer (TMA), and measurements were performed under the following conditions. Apparatus: Thermomechanical analyzer TMA / SDTA2+ (trade name, manufactured by Mettler-Toledo) Load: 25mN Temperature: Raise from 25°C to 250°C at 10°C / min, hold for 5 minutes, then lower from 250°C to 25°C at 10°C / min The linear expansion coefficient B is expressed as follows: when the length of the fixing rotor in the direction of the rotation axis at a temperature of 25°C is expressed as L1s, and the length of the fixing rotor in the direction of the rotation axis at a temperature of 200°C is expressed as L2s, B=((L2s-L1s) / L1s)×100 It was calculated as:

[0115] Examples of the linear expansion coefficients of the elastic layer and surface layer are shown in Figures 8A-C. Figure 8A shows the linear expansion coefficient of the elastic layer. It was confirmed that the filler in the elastic layer was oriented in the thickness direction by applying an electric field, thereby increasing the linear expansion coefficient in the direction of the rotation axis of the fixing rotor. Figure 8B shows the linear expansion coefficient of the surface layer. For the surface layer, by applying heat treatment and controlling the cooling rate on the elastic layer, which has a high linear expansion coefficient in the direction of the rotation axis of the fixing rotor, crystalline regions are formed under stress applied in the direction of the rotation axis of the fixing rotor. Furthermore, by controlling the cooling rate, the number of crystalline regions increases, reducing the linear expansion coefficient. As a result, the difference in the linear expansion coefficients at 200°C between the surface layer and the elastic layer is indicated by the arrow in Figure 8C.

[0116] (3-4) Method for measuring the amount of heat absorbed by the surface layer First, the surface layer is isolated from the fixing rotor. Specifically, the surface layer is peeled off from the substrate together with the elastic layer, and the elastic layer adhered to the surface layer is dissolved in a solvent, thereby isolating only the surface layer.

[0117] The endothermic peak temperature and endothermic amount are measured using a differential scanning calorimeter (product name: Q2000, manufactured by TA Instruments). The melting points of indium and zinc are used for temperature correction of the detector, and the heat of fusion of indium is used for heat correction. Specifically, 4 mg of the surface layer is precisely weighed and placed in an aluminum pan. An empty aluminum pan is used as a reference, and measurements are performed at a temperature rise rate of 20°C / min within a measurement range of 25°C to 400°C. The temperature is raised to 400°C once and held for 5 minutes, then lowered to 25°C at a rate of 20°C / min. During the heating process, the area enclosed by the temperature-endothermic amount curve including the endothermic peak and the baseline is taken as the endothermic amount. From the above, the measured endothermic amount of the surface layer was 25 J / g.

[0118] (4) Actual machine evaluation (wrinkle resistance, image gloss unevenness, fixation) (Evaluation method) Next, the evaluation method in this example will be described. (Evaluation 1: Paper passing wrinkle resistance) The manufactured fixing rotor was used to perform evaluation using the heat fixing device shown in Figure 2. The evaluation conditions were as follows. Test environment: room temperature 23°C, humidity 50% Process speed: 200mm / sec Print speed: 30 pages / minute Paper feeding conditions: A grid image was formed on GF-C081 (manufactured by Nippon Paper Industries Co., Ltd., 81g paper, A4 size), and the paper was fed continuously.

[0119] Every 100,000 sheets, a Mondi Color Copy (manufactured by Mondi Co., Ltd., 250g paper, SRA3 size) was run through the printer, and the printer was checked for scratches at the edge of the A4 paper run area caused by wrinkles in the fixing rotor.If scratches were found, the printer was considered to have reached the end of its service life, and was evaluated according to the following criteria. (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

[0120] (Evaluation 2: Image gloss unevenness evaluation) The manufactured fixing rotor was used to perform evaluation using the heat 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 feed conditions: Vitality (Xerox, 75g paper, A4 size) with black toner at 0.4mg / cm 3 The level of gloss unevenness was visually confirmed and evaluated according to the following criteria. (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

[0121] (Rating 3: Fixability) The manufactured fixing rotor was used to perform evaluation using the heat fixing device shown in Figure 2. The evaluation conditions were as follows. Test environment: room temperature 23°C, relative humidity 50% Process speed: 200mm / sec Print speed: 30 pages / minute Paper feeding conditions: A grid image was formed on GF-C081 (manufactured by Nippon Paper Industries Co., Ltd., 81g paper, A4 size), and the paper was fed continuously.

[0122] Specifically, the fixing temperature of the heat fixing device was adjusted to the surface temperature of the fixing rotor in the copier, and five solid cyan images were formed in succession, and the image density of the fifth solid image was measured. Next, the toner surface of the solid image was heated to 4.9 kPa (50 g / cm 2The toner surface was rubbed three times in the same direction with Silbon paper under a load of 10 ... A: The toner was fixed to the paper at a fixing temperature of 130°C or higher and lower than 140°C. B: The toner was fixed to the paper at a fixing temperature of 140°C or higher and lower than 150°C. C: The toner was fixed to the paper at a fixing temperature of 150°C or higher and lower than 160°C. D: The toner was fixed to the paper at a fixing temperature of 160°C or higher.

[0123] <Example 2> A fixing belt was obtained in the same manner as in Example 1, except that the blending amount was changed so that the area ratio of the filler in the elastic layer was 31%.

[0124] Example 3 A fixing belt was obtained in the same manner as in Example 1, except that the time for the electric field application treatment for forming the elastic layer was changed to 30 seconds and the resin of the PFA tube was changed to 451HP-J (trade name, manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd.).

[0125] Example 4 A fixing belt was obtained in the same manner as in Example 1, except that the time for the electric field application treatment for forming the elastic layer was changed to 20 seconds and the resin of the PFA tube was changed to 451HP-J (trade name, manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd.).

[0126] <Example 5> A fixing belt was obtained in the same manner as in Example 1, except that the blending amount was changed so that the area ratio of the filler in the elastic layer was 30%.

[0127] Example 6 A fixing belt was obtained in the same manner as in Example 1, except that the blending amount was changed so that the area ratio of the filler in the elastic layer was 29%.

[0128] Example 7 A fixing belt was obtained in the same manner as in Example 1, except that the blending amount was changed so that the area ratio of the filler in the elastic layer was 28%.

[0129] Example 8 A fixing belt was obtained in the same manner as in Example 1, except that the blending amount was changed so that the area ratio of the filler in the elastic layer was 38%.

[0130] Example 9 A fixing belt was obtained in the same manner as in Example 1, except that the filler in the elastic layer was changed to boron nitride (trade name: SGP; manufactured by Denka Co., Ltd.) and the filler area ratio was changed to 20%.

[0131] Example 10 A fixing belt was obtained in the same manner as in Example 1, except that the filler in the elastic layer was changed to boron nitride (trade name: SGP; manufactured by Denka Co., Ltd.) and the filler area ratio was changed to 30%.

[0132] Example 11 A fixing belt was obtained in the same manner as in Example 1, except that the amount of filler in the elastic layer was changed so that the area ratio of the filler was 45% and the resin of the PFA tube was changed to 451HP-J (trade name, manufactured by Mitsui-Chemours Fluoroproducts Co., Ltd.).

[0133] <Comparative Example 1> A fixing belt was obtained in the same manner as in Example 1, except that the blending amount was changed so that the area ratio of the filler in the elastic layer was 25%.

[0134] <Comparative Example 2> A fixing belt was obtained in the same manner as in Example 1, except that the blending amount was changed so that the area ratio of the filler in the elastic layer was 50% and the electric field application treatment was not carried out.

[0135] <Comparative Example 3> A fixing belt was obtained in the same manner as in Example 1, except that the surface layer was not heated to a temperature equal to or higher than the melting point of PFA after it was formed.

[0136] <Comparative Example 4> After forming the surface layer, the belt was heated to a temperature above the melting point of PFA, and then the heating barrel was not cooled to 200°C at a rate of 20°C / min. Instead, the belt was removed from the heating barrel into a room temperature atmosphere and rapidly cooled. The fixing belt was obtained in the same manner as in Example 1.

[0137] <Comparative Example 5> The amount of filler in the elastic layer was changed so that the area ratio of the filler was 25%, and no electric field application treatment was performed. In addition, a fixing belt was obtained in the same manner as in Example 1, except that the surface layer was not heated to a temperature equal to or higher than the melting point of PFA after formation.

[0138] The results of these evaluations are summarized in the table below. [Table 1]

[0139] In Table 1, the area percentage is the area percentage of the thermally conductive filler, and h-BN means boron nitride. The embodiment shown in this example was able to satisfy all of the requirements for suppressing wrinkles in the surface layer, suppressing uneven gloss in the image, and improving fixability.

[0140] 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 substrate; a surface layer fixed to the outer peripheral surface side of the elastic layer via an adhesive layer, The thermal conductivity of the elastic layer in the thickness direction is 1.0 W / mK or more, The elastic layer removed from the fixing rotor is pulled in the direction of the rotation axis of the fixing rotor with a load of 25 mN while the temperature is increased from 25°C to 250°C at a temperature increase rate of 10°C / min, and in the TMA curve where the horizontal axis is temperature and the vertical axis is linear expansion coefficient, the linear expansion coefficient at a temperature of 200°C is defined as A, The surface layer removed from the fixing rotor was 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, and in the TMA curve obtained, the horizontal axis is temperature and the vertical axis is linear expansion coefficient, when the linear expansion coefficient at a temperature of 200°C is designated as B, A>B and AB is 2.0% or more. A fixing rotating body characterized by the above. (Configuration 2) the elastic layer contains silicone rubber, 2. The fixing rotating member according to claim 1, wherein the surface layer contains a fluororesin. (Configuration 3) 3. The fixing rotating member according to configuration 1 or 2, wherein A is 3.0 to 5.0%. (Configuration 4) 4. The fixing rotating member according to any one of aspects 1 to 3, wherein B is 0 to 1.5%. (Configuration 5) 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; 5. The fixing rotator according to any one of configurations 1 to 4, wherein the thermally conductive filler has an average arrangement angle Φ of 28 to 90°. (Configuration 6) 6. The fixing rotating member according to any one of configurations 1 to 5, wherein the base layer contains at least one selected from the group consisting of nickel, copper, iron, and aluminum. (Configuration 7) 7. The fixing rotator according to any one of configurations 1 to 6, wherein the fixing rotator is a fixing belt. (Configuration 8) A heat fixing device having a heating member and a pressure member disposed opposite the heating member, 8. A heat fixing device, 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 7. (Configuration 9) An electrophotographic image forming apparatus including a heat fixing device, The heat fixing device has a heating member and a pressure member disposed opposite the heating member, At least one of the heating member and the pressure member is a fixing member according to any one of configurations 1 to 7. An electrophotographic image forming apparatus characterized in that it is a rotating body. [Explanation of symbols]

[0141] 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 film, 35: Secondary transfer roller, 40: heat 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 type thermistor, 46: heater holder, 101: core, 200: corona charger, 201: front block, 202: rear block, 203, 204: shield, 205: discharge wire, 206: grid, 401-1 1st cross section, 401-2 2nd cross section, P: recording material, T: toner

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 substrate; a surface layer fixed to the outer peripheral surface side of the elastic layer via an adhesive layer, The thermal conductivity of the elastic layer in the thickness direction is 1.0 W / mK or more, The elastic layer removed from the fixing rotor is pulled in the direction of the rotation axis of the fixing rotor with a load of 25 mN while the temperature is increased from 25°C to 250°C at a temperature increase rate of 10°C / min. In the TMA curve, the horizontal axis is temperature and the vertical axis is linear expansion coefficient, and A is the linear expansion coefficient at a temperature of 200°C. The surface layer removed from the fixing rotor was 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, and in the TMA curve obtained, the horizontal axis is temperature and the vertical axis is linear expansion coefficient, when the linear expansion coefficient at a temperature of 200°C is designated as B, A>B and A-B is 2.0% or more; A fixing rotating body characterized by the above.

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

3. 2. The fixing rotating member according to claim 1, wherein A is 3.0 to 5.0%.

4. 2. The fixing rotating member according to claim 1, wherein the B is 0 to 1.5%.

5. 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°.

6. 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.

7. The fixing rotor according to claim 1 , wherein the fixing rotor is a fixing belt.

8. A heat fixing device having a heating member and a pressure member disposed opposite the heating member, 8. A heat fixing device, wherein at least one of the heating member and the pressure member is the fixing rotatable member according to claim 1.

9. An electrophotographic image forming apparatus including a heat fixing device, the heat fixing device has a heating member and a pressure member disposed opposite the heating member, 8. 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