Fixing rotor, fixing device, electrophotographic image forming apparatus, and method for manufacturing fixing rotor

Abstract

To provide a rotating body for fixing and the like that can maintain high toner releasability for a longer time than before and can maintain wear resistance against a sheet.SOLUTION: A rotating body for fixing has a base layer, an elastic layer, and a surface layer in this order. The surface layer includes a tetrafluoroethylene-perfluoroalkyl vinyl ether polymer and perfluoropolyether. The tetrafluoroethylene-perfluoroalkyl vinyl ether polymer forms holes. The surface layer has holes that open in a first surface constituting an outer surface of the rotating body for fixing. At least part of the holes includes the perfluoropolyether. The content of the perfluoropolyether in the surface layer is 20 mass% to 60 mass%. The degree of orientation A of molecules of the tetrafluoroethylene-perfluoroalkyl vinyl ether polymer in a direction orthogonal to a circumferential direction of the surface layer is 35% to 75%.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a fixing rotator, a fixing device, an electrophotographic image forming apparatus, and a method for manufacturing the fixing rotator. [Background technology]

[0002] In a fixing device used in an electrophotographic image forming apparatus (hereinafter also referred to as an "image forming apparatus") such as a copier or laser printer, a pair of rotating bodies, such as a pair of heated rollers, a film and a roller, a belt and a belt, are pressed together. A recording medium, such as paper, carrying an image formed with unfixed toner is introduced into the pressure contact area formed between these rotating bodies (hereinafter referred to as the "fixing nip"), and the unfixed toner is heated and melted, thereby fixing the image to the recording medium. The fixing rotating body that comes into contact with the unfixed toner image on the recording medium may be called a fixing roller, a fixing film, or a fixing belt, depending on its form. In recent years, the paper media used for forming electrophotographic images has become increasingly diverse. For example, 2 There is a demand for a fixing member that can handle thin paper such as paper rolls. However, because such thin paper has low rigidity, when a fixing member such as a conventional fixing rotor is used, melted toner adheres to the surface of the fixing rotor during thermal fixing, causing the thin paper to wrap around the fixing rotor. In order to stably form an electrophotographic image on thin paper, it is necessary to provide the surface of the fixing rotor with high toner releasability. Patent Document 1 discloses a fixing member whose surface layer contains a fluororesin and perfluoropolyether (hereinafter also referred to as "PFPE") and can maintain high toner releasability for a long period of time. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019 / 181796 [Non-patent literature]

[0004] [Non-Patent Document 1] "Journal of the Japan Adhesion Society", Japan Adhesion Society, 1972, Vol. 8, No. 3, pp. 131-141 Summary of the Invention [Problem to be solved by the invention]

[0005] According to the studies of the present inventors, the fixing member disclosed in Patent Document 1 exhibits excellent toner release properties over a long period of time. However, in the surface layer of the fixing member disclosed in Patent Document 1, the fluorinated oil exists without phase separation from the fluorinated resin (paragraph

[0018] of Patent Document 1). In this case, there is a limit to the amount of fluorinated oil that can be contained in the surface layer. Therefore, in order to impart excellent toner release properties over a longer period of time to a fixing rotating body, the present inventors recognized that technological development is necessary to provide a fixing rotating body that can retain a larger amount of PFPE and can stably supply the PFPE to its outer surface. [Means for solving the problem]

[0006] One aspect of the present disclosure is to provide a fixing rotating body that can maintain high toner releasability and abrasion resistance against paper for a long period of time. Another aspect of the present disclosure is directed to providing a fixing device and an electrophotographic image forming apparatus that contribute to stable formation of high-quality electrophotographic images over a long period of time. Furthermore, another aspect of the present disclosure is to provide a toner having high toner release properties and abrasion resistance to paper. The present invention aims to provide a method for manufacturing a fixing rotating body that can be maintained for a long period of time.

[0007] According to one aspect of the present disclosure, A fixing rotating body having a base layer, an elastic layer, and a surface layer in this order, the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether; the surface layer has pores that open to a first surface that constitutes the outer surface of the fixing rotor, At least a portion of the pores contain the perfluoropolyether; the content of the perfluoropolyether in the surface layer is 20% by mass to 60% by mass, The fixing rotor has a degree of orientation A of the tetrafluoroethylene-perfluoroalkyl vinyl ether molecules in the direction perpendicular to the circumferential direction of the surface layer of 35 to 75%.

[0008] According to another aspect of the present disclosure, A fixing device comprising a fixing rotor and a heating unit for heating the fixing rotor, the fixing rotating body has a base layer, an elastic layer, and a surface layer in this order; the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether; the surface layer has pores that open to a first surface that constitutes the outer surface of the fixing rotor, At least a portion of the pores contain the perfluoropolyether; the content of the perfluoropolyether in the surface layer is 20% by mass to 60% by mass, the degree of orientation A of the tetrafluoroethylene-perfluoroalkyl vinyl ether molecules in the direction perpendicular to the circumferential direction of the surface layer is 35 to 75%; A fixing device is provided.

[0009] According to another aspect of the present disclosure, An electrophotographic image forming apparatus including a fixing device, the fixing device includes a fixing rotor and a heating means for heating the fixing rotor, the fixing rotating body has a base layer, an elastic layer, and a surface layer in this order; the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether; the surface layer has pores that open to a first surface that constitutes the outer surface of the fixing rotor, At least a portion of the pores contain the perfluoropolyether; the content of the perfluoropolyether in the surface layer is 20% by mass to 60% by mass, the degree of orientation A of the tetrafluoroethylene-perfluoroalkyl vinyl ether molecules in the direction perpendicular to the circumferential direction of the surface layer is 35 to 75%; An electrophotographic imaging apparatus is provided.

[0010] According to another aspect of the present disclosure, A method for manufacturing a fixing rotating body, comprising: the fixing rotor has a base layer, an elastic layer, and a surface layer in this order; the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether; the surface layer has pores that open to a first surface that constitutes the outer surface of the fixing rotor, At least a portion of the pores contain the perfluoropolyether; the content of the perfluoropolyether in the surface layer is 20% by mass to 60% by mass, the degree of orientation A of the tetrafluoroethylene-perfluoroalkyl vinyl ether molecules in the direction perpendicular to the circumferential direction of the surface layer is 35 to 75%, The manufacturing method comprises: (i) preparing a resin tube containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, the degree of molecular orientation A of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer being 35 to 75%; (ii) preparing a laminate having a base layer in the shape of an endless belt or a roller, an elastic layer on the outer peripheral surface of the base layer, and the resin tube on the outer peripheral surface of the elastic layer; (iii) a step of immersing the laminate in a first perfluoropolyether heated to a temperature of 25°C or higher but lower than Tp (°C), where Tp is the melting point of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, to impregnate the resin tube with the perfluoropolyether; (iv) a step of removing at least a portion of the perfluoropolyether in the resin tube of the laminate obtained in the step (iii) using a solvent to form pores in the resin tube that are open to the outer peripheral surface of the resin tube; and (v) containing a second perfluoropolyether in at least a portion of the pores; obtaining a fixing rotor having a surface layer containing the second perfluoropolyether in at least some of the pores; A method for manufacturing a fixing rotor having the above structure is provided. [Brief explanation of the drawings]

[0011] [Figure 1] 1A is a surface observation image of the resin layer of the fixing rotating member described in Example 1, (B) is a cross-sectional image of the resin layer observed in a cross section along the belt circumferential direction, and (C) is a cross-sectional image of the surface layer. [Figure 2] 1A is a cross-sectional view of a fixing belt and a fixing roller. [Figure 3] FIG. 1 is a cross-sectional view of a fixing device using a fixing belt. [Figure 4] FIG. 1 is a cross-sectional view of a fixing device using a fixing roller. [Figure 5] 1 is a schematic cross-sectional view illustrating one embodiment of an electrophotographic image forming apparatus. [Figure 6] 1 is a graph showing the relationship between the angle of β rotation and the X-ray diffraction intensity of a sample in which PFA molecules are oriented in the MD direction. DETAILED DESCRIPTION OF THE INVENTION

[0012] The expressions "XX or more and YY or less" or "XX to YY" that represent a numerical range mean a numerical range including the endpoints, that is, the lower limit and the upper limit, unless otherwise specified. When numerical ranges are stated in stages, the upper and lower limits of each numerical range can be combined in any way.

[0013] The present inventors have conducted extensive research to obtain a fixing rotor that can maintain excellent toner releasability and abrasion resistance even after long-term use. As a result, they have found that the surface layer contains tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), the surface layer has pores that open to a first surface that constitutes the outer surface of the fixing rotor, and at least some of the pores contain perfluoropolyether, the content of the perfluoropolyether in the surface layer is 20 to 60 mass %, and the molecules of PFA in the surface layer are oriented in a direction (hereinafter sometimes referred to as "MD") perpendicular to the circumferential direction (hereinafter sometimes referred to as "TD"; "TD" stands for transverse direction) of the fixing rotor. It has been found that the degree of orientation A in the "MD" direction is 35 to 75% and contributes to achieving the above object. The surface layer has pores, which allow PFPE to be contained in the pores, and therefore the fixing rotor can retain more PFPE in its surface layer than the surface layer disclosed in Patent Document 1, which retains PFPE in a fluororesin without phase separation. Furthermore, since the openings are open to the first surface of the surface layer, the PFPE in the pores can be transferred to the first surface. Furthermore, the degree of orientation A of the PFA molecules in the surface layer in the MD of the fixing rotor is 35 to 75%, i.e., the MD orientation of the PFA molecules is optimized, thereby more reliably suppressing wear of the first surface of the surface layer and tearing of the surface layer in the TD. As a result, loss of openings in the first surface of the surface layer due to wear is suppressed, and more stable migration of PFPE to the first surface present in the voids can be achieved. In addition, leakage of PFPE present in the voids to the first surface due to tearing of the surface layer can be prevented. As a result, it is believed that the fixing rotating member according to this embodiment can maintain excellent toner releasability for a longer period of time compared to the fixing member according to Patent Document 1.

[0014] The fixing rotor will be described in detail below. 1. Rotating body for fixing The fixing rotating body is, for example, a fixing roller, a fixing film, a fixing belt, etc. The fixing rotating body has a base layer, an elastic layer, and a surface layer in this order. 2(A) and 2(B) are cross-sectional views showing different embodiments of the fixing rotor. Fig. 2(A) shows a fixing rotor having an endless belt shape (hereinafter also referred to as "fixing belt 11"), and Fig. 2(B) shows a roller-shaped fixing rotor (hereinafter also referred to as "fixing roller 12"). 2(A) and 2(B) has a base layer 13, an elastic layer 14 that covers the outer surface of the base layer, and a surface layer 15 that covers the surface of the elastic layer opposite to the side facing the base layer. The surface layer 15 may be adhered to the surface of the elastic layer 14 opposite to the side facing the base layer by an adhesive layer (not shown).

[0015] (1) Base layer The material of the base layer 13 is not particularly limited, and may be any known material used as a base layer for a fixing member such as a fixing rotor, etc. For example, metals and alloys such as aluminum, iron, stainless steel, and nickel, and heat-resistant resins such as polyimide may be used. In the fixing belt 11, a substrate having an endless belt shape may be used as the base layer 13. In this case, the material of the base layer 13 may be, for example, nickel, stainless steel, or polyimide, which has excellent heat resistance. The thickness of the base layer 13 is not particularly limited, but is preferably 20 μm or more and 100 μm or less from the viewpoints of strength, flexibility, and heat capacity.

[0016] In the fixing roller 12, for example, a solid or hollow core is used as the base layer 13. The core may be made of a metal or alloy such as aluminum, iron, or stainless steel. When a hollow core is used, it is possible to provide a heat source inside. The outer surface of the base layer 13 may be subjected to a surface treatment to impart adhesion to the elastic layer 14. The surface treatment may be one or a combination of physical treatments such as blasting, lapping, or polishing, or chemical treatments such as oxidation, coupling agent treatment, or primer treatment.

[0017] When the elastic layer 14 containing silicone rubber is provided on the surface of the base layer 13, the base layer 13 and the elastic layer 14 are In order to improve adhesion to the conductive layer 14, it is preferable to subject the surface of the base layer 13 to a primer treatment. The primer used in the primer treatment may be, for example, a paint in which a silane coupling agent, a silicone polymer, a hydrogenated methylsiloxane, an alkoxysilane, a reaction-accelerating catalyst, and a colorant such as red iron oxide are appropriately mixed and dispersed in an organic solvent.

[0018] The primer can be appropriately selected depending on the material of the base layer 13, the type of elastic layer 14, or the form of crosslinking reaction. In particular, when the elastic layer 14 contains a large amount of unsaturated aliphatic groups, a primer containing a hydrosilyl group is preferably used to impart adhesiveness by reacting with the unsaturated aliphatic groups. When the elastic layer 14 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 a step of applying the primer to the outer surface of the base layer 13 (the surface to be bonded to the elastic layer 14) and drying or baking the primer.

[0019] (2) Elastic layer The material of the elastic layer 14 is not particularly limited, and any known material used as an elastic layer for a fixing member such as a fixing rotor can be used. It is preferable that the elastic layer 14 contains silicone rubber, which has excellent heat resistance. In addition, addition-curing liquid silicone rubber is preferably used as the raw material for the silicone rubber. The thickness of the elastic layer 14 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. When the fixing rotor is the fixing belt 11, the thickness of the elastic layer 14 is preferably 100 μm or more and 500 μm or less, and more preferably 200 μm or more and 400 μm or less.

[0020] When the fixing rotating body is the fixing roller 12, the thickness of the elastic layer 14 is preferably 0.1 mm (100 μm) or more and 3.0 mm or less, and more preferably 0.3 mm (300 μm) or more and 2.0 mm or less. By setting the thickness of the elastic layer 14 within this range, a sufficient width of the fixing nip portion can be ensured when the fixing rotatable body is incorporated into a fixing device. Furthermore, since the elastic layer contains silicone rubber, which has poor chemical affinity with fluorine oil, the fluorine oil contained in the surface layer is less likely to migrate to the elastic layer even with long-term use, and is instead supplied primarily to the surface of the fixing rotor.

[0021] The elastic layer 14 may contain a filler, which is added to control the thermal conductivity, heat resistance, and elastic modulus. Specific examples include silicon carbide (SiC), silicon nitride (Si3N4), silica (SiO2), boron nitride (BN), aluminum nitride (AlN), alumina (Al2O3), iron oxide (Fe2O3), zinc oxide (ZnO), magnesium oxide (MgO), titanium oxide (TiO2), copper (Cu), aluminum (Al), silver (Ag), iron (Fe), nickel (Ni), carbon black (C), carbon fiber (C), and carbon nanotubes (C).

[0022] Furthermore, a reaction control agent (blocking agent) called an inhibitor for controlling the reaction initiation time may be blended into the material constituting the elastic layer 14. Known reaction control agents such as methylvinyltetrasiloxane, acetylene alcohols, siloxane-modified acetylene alcohol, and hydroperoxide are used.

[0023] (3) Surface layer The surface layer 15 is made of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. The surface layer contains polyfluoroethylene (PFA) and perfluoropolyether (PFPE). As shown in FIG. 1(B), the surface layer has pores 3 that open to a first surface 101 that constitutes the outer surface of the fixing rotor. The outer surface of the fixing rotor is defined as the surface that comes into contact with unfixed toner on the recording material during fixing. Here, it is preferable that the pores 3 do not have a shell. In other words, it is preferable that the walls of the pores 3 are formed from the solid portion of the surface layer, specifically, the resin portion 1 containing PFA. At least some of the pores contain perfluoropolyether (PFPE) 4. For example, the pores are filled with PFPE.

[0024] Furthermore, the surface layer satisfies the following requirements 1) and 2). Requirement 1) The content of the perfluoropolyether in the surface layer is 20% by mass to 60% by mass. Requirement 2) The degree of orientation A of the PFA in the surface layer in the MD is 35 to 75%.

[0025] Regarding the above requirement 1), the content of perfluoropolyether in the surface layer is 20% by mass to 60% by mass, preferably 25% by mass to 60% by mass, and more preferably 25% by mass to 45% by mass. A PFPE content within the above range contributes to a more stable migration of PFPE to the outer surface of the fixing rotor according to the present disclosure over a longer period of time.

[0026] Regarding requirement 2), by setting the degree of orientation A to 35% or more, wear of the first surface of the surface layer due to contact with paper can be more reliably suppressed. By suppressing wear of the first surface of the surface layer, openings connected to the voids, which are important for stable migration of PFPE present in the voids to the first surface, can be maintained for a long period of time. As a result, the life of the fixing rotor can be further extended. Furthermore, by setting the degree of orientation A to 75% or less, even if the surface layer is repeatedly bent as the fixing rotor is heated and rotated repeatedly, it is possible to reliably prevent the occurrence of cracks in the TD of the surface layer. The degree of orientation A is preferably 40 to 70%, and more preferably 50 to 60%.

[0027] Here, the degree of orientation A is calculated by rotating a sample prepared from the surface layer 360° in the in-plane direction (β rotation) while measuring the relationship between the β rotation angle and the X-ray diffraction intensity using X-ray diffraction in transmission mode. Specifically, the endless surface layer is cut open along the MD direction to prepare a film-like sample. This sample is fixed to a sample attachment and then fixed to a rotating sample stage attached to an X-ray diffraction instrument. The sample is then placed in the X-ray diffraction instrument so that the TD of the surface layer coincides with the measurement direction. When the sample is rotated 360° in the in-plane direction, the X-ray diffraction intensity obtained at rotation angles of 90° and 270° indicates the orientation state of the PFA in the MD direction. Note that the tetrafluoroethylene (hereinafter also referred to as "TFE") unit portion of the PFA molecule crystallizes. The crystalline structure derived from the TFE unit exhibits the strongest peak at 2θ = 18° in X-ray diffraction measurements in transmission mode. Therefore, in the X-ray diffraction measurement for calculating the degree of orientation of the surface layer, the sample is fixed at 2θ=18° and then β-rotated.

[0028] Figure 6 shows a graph plotting the X-ray diffraction intensity versus the β-rotation angle, obtained by using the above-mentioned analytical method for a sample prepared from a surface layer in which the PFA molecules are oriented in the MD. As mentioned above, the sample was placed so that the TD of the surface layer coincided with the measurement direction, and therefore peaks due to the PFA molecules oriented in the MD appear at 90° and 270° positions. The stronger the orientation in the MD, the narrower the half-width W of the peak and the sharper the peak. Therefore, the degree of orientation A (%) of the PFA molecules in the MD direction of the surface layer is calculated by the following formula (1): This can be shown. A = [(360-ΣW) / 360] × 100(%) The half-width W is defined as the width of the peak at a position half the distance (h) between the peak top (β rotation angle = 90°, 270° in Figure 6) of the peak indicating the orientation of the PFA molecules in MD and the baseline indicated by the dotted line in Figure 6. A method for producing a surface layer having such an orientation degree A and containing 20 to 60 wt % of PFPE will be described later.

[0029] The average opening diameter of the openings on the outer surface of the surface layer is preferably 1 nm or more and 5 μm or less, more preferably 50 nm or more and 140 nm or less. Setting the average opening diameter within the above range contributes to the stable maintenance of excellent toner releasability. The average opening diameter of the openings on the first surface is the average diameter of circles having the same area as the area of ​​the portions corresponding to the openings in the binarized image used to calculate P1, which will be described later. Specific methods will be described later.

[0030] The thickness of the surface layer is preferably 12 μm or more and 100 μm or less, and more preferably 15 μm or more and 85 μm or less.

[0031] <pfa> The PFA contained in the surface layer will be described in detail below. PFA is a copolymer of perfluoroalkyl vinyl ether (hereinafter referred to as "PAVE") and tetrafluoroethylene (hereinafter referred to as "TFE"). The number of carbon atoms in the perfluoroalkyl chain in PAVE is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 to 3. The PAVE is preferably selected from perfluoromethyl vinyl ether (CF2=CF-O-CF3), perfluoroethyl vinyl ether (CF2=CF-O-CF2CF3) and perfluoropropyl vinyl ether (CF2=CF-O-CF2CF2CF3). The melting point of PFA is preferably 280°C to 320°C, and more preferably 290°C to 310°C.

[0032] As the PFA, commercially available products can be used, and specific examples are given below. "451HP-J", "959HP-Plus", "350-J", "950HP-Plus" (all product names, manufactured by Mitsui Chemours Fluoroproducts); "P-66P", "P-66PT", "P-802UP" (all product names, manufactured by AGC); "AP-230", "AP-231SH", etc. (all product names, manufactured by Daikin Industries, Ltd.); "6502N" (product name, manufactured by 3M).

[0033] <Perfluoropolyether (PFPE)> The PFPE contained in at least a portion of the pores will be described in detail. The PFPE contained in the pores may be referred to as a second PFPE to distinguish it from the PFPE (first PFPE) used to form the pores, which will be described later. However, this does not mean that the second PFPE is the same PFPE as the first PFPE. The second PFPE is not particularly limited, and known PFPEs can be used.Preferably, PFPEs having a structure represented by the following formula (1) can be used.The second PFPE is preferably one that becomes oily near the melting point of PFA, and particularly preferably one that becomes oily at a temperature lower than the melting point of PFA, for example, at 200°C.

[0034] [ka]

[0035] (In formula (1), a, b, c, d, e, and f each independently represent 0 or a positive integer, satisfying 1≦a+b+c+d+e+f≦600, and at least one of a, b, c, and d being a positive integer.) In addition, the order of the repeating units in formula (1) is not limited to the order described above. Furthermore, each repeating unit in formula (1) may exist in a plurality of places in PFPE. That is, the PFPE represented by formula (1) may be a block copolymer or a random copolymer.

[0036] Examples of commercially available PFPEs include PFPEs having a structure represented by the following formula (2) (e.g., Demnum S-200, Demnum S-65 (both trade names); manufactured by Daikin Industries, Ltd.), PFPEs having a structure represented by the following formula (3) (e.g., Krytox XHT-1000, Krytox VPF16256, Krytox GPL-107, Krytox GPL-106, Krytox GPL-105, Krytox GPL-104, Krytox GPL-106), and the like. Examples of PFPEs include Krytox GPL-103, Krytox GPL-102, and Krytox GPL-101 (all trade names; manufactured by Chemours), PFPEs having a structure represented by the following formula (4) (e.g., Fomblin M60, Fomblin M100, and Fomblin Z25 (all trade names; manufactured by Solvay Specialty Polymers), and PFPEs represented by the following formula (5) (e.g., Fomblin Y45 and Fomblin Y25 (all trade names; manufactured by Solvay Specialty Polymers)). The perfluoropolyether preferably has at least one structure selected from the group consisting of the following formulas (2) to (5).

[0037] [ka] (In formula (2), n is a positive number, and n is a number in the range that makes the viscosity of PFPE at a temperature of 40°C range from 30 mPa·s to 500 mPa·s.)

[0038] [ka] (In formula (3), n' is a positive number, and n' is a number within the range of 10 mPa·s to 2500 mPa·s for the viscosity of PFPE at a temperature of 40°C.)

[0039] [ka] (In formula (4), n'' and m are each independently a positive number, m / n'' is a number that is 0.5 or greater and 2 or less, and n''+m is a number that causes the viscosity of the PFPE at a temperature of 40°C to be in the range of 20 mPa s to 1400 mPa s.)

[0040] [ka]

[0041] (In formula (5), n''' and m' are each independently a positive number, m' / n''' is a number that is 20 or greater and 1000 or less, and n'''+m' is a number that causes the viscosity of the PFPE at a temperature of 40°C to fall within the range of 20 mPa s to 1200 mPa s.)

[0042] The viscosity of the second PFPE is preferably 300 mPa·s to 2500 mPa·s, and more preferably 350 mPa·s to 2000 mPa·s. A PFPE in this viscosity range contributes to stable migration of the surface layer from the pores to the first surface. The viscosity here is measured using a dynamic viscoelasticity measuring device (rheometer) with a cone angle of 1 degree and a cone radius of 20 mm at a measurement temperature of 40°C and a shear rate of 100 s -1 The value is obtained when the sample is rotated at 100° C. for 60 seconds. An example of a viscoelasticity measuring device is the "DHR-2" (trade name, manufactured by TA Instruments).

[0043] Examples of commercially available PFPEs within the above viscosity range include Krytox GPL-105 (viscosity 301 mPa·s), Krytox GPL-106 (viscosity 459 mPa·s), Krytox GPL-107 (viscosity 852 mPa·s), Krytox VPF16256 (viscosity 1403 mPa·s), Krytox XHT-1000 (viscosity 1941 mPa·s), Fomblin M60 (viscosity 586 mPa·s), and Fomblin M100 (viscosity 1327 mPa·s).

[0044] The content of perfluoropolyether in the surface layer is preferably 20% by mass or more and 60% by mass or less, more preferably 25% by mass or more and 45% by mass or less. When the content is 20% by mass or more, toner releasability is maintained well even during long-term use. When the content is 60% by mass or less, wear of the surface layer due to use can be more reliably prevented.

[0045] Furthermore, it is preferable that the fixing rotor according to the present disclosure satisfies the following requirements: That is, a first observation region of 8 μm length × 11 μm width is placed on the outer circumferential surface of a PFA tube obtained by removing the PFPE in the pores of the surface layer from the first surface side using a solvent, and P1 is the ratio of the sum of the areas of the openings observed in the first observation region to the area of ​​the first observation region. A vertical line is placed at a predetermined position on a cross section of the surface layer obtained by removing the PFPE in the pores of the surface layer from the first surface side using a solvent, the cross section including the entire thickness of the surface layer in the direction along the circumferential direction of the fixing rotor. A second observation area measuring 8 μm x 11 μm is placed, and when the ratio of the total area of ​​pores observed in the second observation area to the area of ​​the second observation area is defined as P2, P2 / P1 must be 1.3 or greater.

[0046] By making P1 and P2 have the above-mentioned relationship, the surface layer can retain a sufficient amount of PFPE, and can stably transfer this PFPE to the first surface.P2 / P1 is more preferably 5.0 or more, and even more preferably 7.0 or more.On the other hand, from the viewpoint of balancing the amount of PFPE that the surface layer can retain and the transfer of this PFPE to the first surface, the upper limit is preferably 20.0 or less, more preferably 15.0 or less.

[0047] The calculation method of P1 and P2 will be described in detail in the Examples. P1 is preferably 1.0% or more, more preferably 1.5% or more. The upper limit is preferably 15.0% or less, more preferably 10.0% or less. For example, P1 is preferably 1.0% or more and 15.0% or less. When P1 is 1.0% or more, migration of the surface layer of PFPE in the pores to the first surface is not easily inhibited, and stable toner releasability can be imparted to the first surface. Also, when P1 is 15.0% or less, excessive migration of PFPE in the pores to the first surface can be suppressed, contributing to maintaining stable toner releasability over a long period of time.

[0048] Furthermore, P2 is preferably 20.0% or more, more preferably 25.0% or more. There is no particular upper limit, but it is preferably 60.0% or less, more preferably 50.0% or less. For example, P2 is preferably 20.0% or more and 60.0% or less. When P2 is 20.0% or more, the surface layer can retain more PFPE, and the first surface can be provided with stable toner release properties over a longer period of time. On the other hand, when P2 is 60.0% or less, wear of the surface layer can be better prevented.

[0049] <Method of manufacturing the fixing rotor> A non-limiting example of a method for manufacturing the fixing rotating body according to one embodiment of the present disclosure includes the following steps (i) to (vi). Note that step (vi) is an optional step that is required when the above-mentioned P2 / P1 is set to 1.3 or more. Furthermore, although an example in which a PFA tube is used to form the surface layer is given, the surface layer according to the present disclosure is not limited to being formed using a PFA tube. Step (i): preparing a tube containing PFA having an orientation degree A according to the present disclosure (hereinafter also referred to as a "PFA tube"); Step (ii): A step of preparing a laminate including a base layer having an endless belt shape or a roller shape, an elastic layer on the outer peripheral surface of the base layer, and the elastic layer, and then covering the outer peripheral surface of the laminate with the PFA tube prepared in the above step (i) to prepare a PFA tube-coated laminate; Step (iii): a step of immersing the PFA tube-covered laminate in a first PFPE heated to a temperature range of less than Tp and not less than 25°C, where Tp (°C) is the melting point of the PFA constituting the PFA tube, to impregnate the resin tube with the first PFPE (impregnation step-1); Step (vi): cooling the PFA tube-coated laminate obtained in step (iii), in which the PFA tube is impregnated with the first PFPE, to room temperature (25°C); Step (v): removing at least a portion of the first PFPE in the PFA tube of the PFA tube-covered laminate obtained in step (iv) from the surface (outer circumferential surface) of the PFA tube opposite to the surface facing the elastic layer using a solvent, thereby forming pores in the PFA tube that are open to the outer circumferential surface of the PFA tube; and Step (vi): A step of impregnating the second perfluoropolyether into at least some of the pores to obtain a fixing rotor having a surface layer containing the second perfluoropolyether in at least some of the pores (impregnation step-2).

[0050] One method for obtaining a PFA tube with an orientation degree A of 35 to 75% in step (i) is, for example, extruding molten PFA through a cylindrical die. By extruding molten PFA, the PFA molecules tend to be oriented in the flow direction, i.e., MD. Therefore, a PFA tube with an orientation degree in the range of 35 to 75% can be easily produced. The orientation degree A of a PFA tube produced by cylindrical extrusion (hereinafter also referred to as a "cylindrically extruded PFA tube" (cylindrically extruded resin tube)) can be controlled, for example, by the temperature of the PFA during cylindrical extrusion. For example, within the typical temperature range (e.g., 300 to 400°C) used for melt-extruding PFA, a lower temperature increases the viscosity of the PFA during extrusion, increasing the internal stress of the molten PFA flowing in the extrusion direction and enhancing the molecular orientation in the MD. Furthermore, a higher temperature decreases the viscosity of the PFA, thereby reducing the molecular orientation in the MD.

[0051] The amount of the first PFPE impregnated into the PFA tube can be adjusted, for example, by the temperature of the first PFPE during impregnation, the viscosity of the first PFPE, and the contact time between the resin layer and the first PFPE. Specifically, for example, the higher the temperature of the first PFPE is within a range of 25°C or higher and lower than Tp, the lower the viscosity of the first PFPE is, and the longer the contact time is, the more the amount of the first PFPE impregnated into the PFA tube can be increased.

[0052] Here, the preferred viscosity of the first PFPE is preferably 350 mPa·s or less, particularly 320 mPa·s or less, and further 120 mPa·s or less. There is no particular lower limit, but it is preferably 10 mPa·s or more, particularly 25 mPa·s or more. The viscosity of the first PFPE can be, for example, 10 mPa·s to 350 mPa·s. Commercially available PFPEs in this viscosity range include Krytox GPL-101 (viscosity 12 mPa·s), Krytox GPL-102 (viscosity 26 mPa·s), Krytox GPL-103 (viscosity 54 mPa·s), Krytox GPL-104 (viscosity 111 mPa·s), Fomblin M03 (viscosity 30 mPa·s), and Krytox GPL-105 (viscosity 301 mPa·s).

[0053] For example, when the viscosity of the first PFPE is 54 mPa·s, the thickness of the PFA tube is 20 μm, the degree of orientation A of the PFA tube is 35°, the melting point Tp of the PFA tube is 296°C, and the temperature of the first PFPE contacted with the outer surface of the PFA tube is 280°C, a PFPE-containing PFA tube with a first PFPE content of 25% by mass can be produced with a contact time of 1 minute. Here, the content is defined as the percentage (%) of the mass of the PFPE impregnated in the resin layer relative to the sum of the mass of the resin layer itself and the mass of the PFPE impregnated in the resin layer. Then, by removing the PFPE from the PFPE-containing PFA tube with a PFPE content of 25% by mass using a solvent, a PFA tube with voids and a P2 value of 28%, as described below, can be obtained.

[0054] On the other hand, the PFPE used in the examples of Patent Document 1, "Krytox GPL106," has a viscosity of 459 mPa·s. When such a PFPE was brought into contact with a PFA tube containing PFA at a temperature of 345°C for 5 minutes, a PFPE-containing PFA tube with a PFPE content of 24% by mass was obtained. However, with this level of PFPE content, the PFPEs did not aggregate within the PFA tube. Therefore, even when the PFPE was subsequently eluted using a fluorine-based solvent, no pores were formed in the PFA tube.

[0055] In step (iii) (impregnation step-1), the content of PFPE in the resin layer impregnated with the first PFPE is preferably 25% by mass to 50% by mass, more preferably 30% by mass. ~45% by mass.

[0056] Any method can be used to bring the PFA tube and PFPE into contact with each other in the production of the fixing rotor, as long as the PFPE can be brought into contact with the resin layer at a temperature of 25° C. or higher and lower than Tp. The PFA tube to be brought into contact with the PFPE may be a PFA tube in a laminate in which a base layer, an elastic layer, and a resin layer are laminated in advance, or a PFA tube in a state in which the surface to be bonded to the elastic layer is masked. The contact method may be, for example, a dipping method.

[0057] Next, in step (iii), if the temperature of the first PFPE is set to, for example, 280°C or higher, the PFA tube impregnated with the first PFPE in step (iii) is in a high-temperature state, so in step (iv), the PFA tube-coated laminate is cooled to room temperature, for example, about 25°C. This cooling step causes the PFA tube, which was expanded in step (iii), to shrink. At that time, the first PFPE near the outer surface of the PFA tube is released outside the PFA tube. Then, by removing the first PFPE from the PFA tube with a solvent in step (v), open pores are formed on the outer peripheral surface of the PFA at the sites where the first PFPE was present.

[0058] By undergoing the above steps (iv) and (v), the ratio P2 of the pore area per unit area in the cross section of the PFA tube in a direction parallel to the circumferential direction of the laminate can be made larger than the ratio P1 of the opening area per unit area on the first surface. Although the reason for this is unclear, the PFA tube, which thermally expands due to the high temperature in step (iii), shrinks during the cooling process in step (iv). However, the first surface of the PFA tube cools faster than the surface on the elastic layer side, resulting in a greater degree of shrinkage. As the first surface shrinks, the first PFPE present near the first surface of the PFA tube is pushed outward. As a result, the openings on the first surface of the PFA tube shrink. Meanwhile, the first PFPE that has penetrated deep into the thickness of the PFA tube, for example, near the surface on the elastic layer side, is not expelled from the PFA tube even when the PFA tube shrinks, but remains within the PFA tube. Therefore, the size of the aggregated portions of the first PFPE that become voids after the first PFPE is removed is hardly reduced. As a result, the ratio (P2 / P1) of the porosity P2 to the opening ratio P1 on the first surface of the fixing rotor formed through step (v) becomes large. Here, the value of P2 / P1 can be adjusted by the amount of the first PFPE impregnated into the PFA tube in the impregnation step-1 of step (iii). That is, by increasing the amount of PFPE impregnated into the PFA tube, the voids inside the PFA tube can be increased, and the value of P2 increases. Furthermore, by increasing the amount of PFPE impregnated into the PFA tube, the openings on the first surface of the PFA tube increase, and the value of P1 also increases. Although the reason for this is unclear, the degree of increase in P1 due to an increase in the amount of PFPE impregnated into the PFA tube is greater than the degree of increase in P2. Therefore, by increasing the amount of the first PFPE impregnated into the PFA tube, it is possible to adjust P2 / P1 in a smaller direction.

[0059] In step (v), to remove the first PFPE impregnated into the PFA tube, the PFA tube is immersed in a solvent capable of dissolving the first PFPE but not dissolving PFA so that the outer surface of the PFA tube is wet. Here, the "solvent capable of dissolving PFPE" refers to, for example, a solvent that dissolves 10 g or more of PFPE per 100 g of solvent at 25°C. On the other hand, the "solvent that does not dissolve PFA" refers to a solvent that dissolves 1 g or less of PFA per 100 g of solvent at 25°C. Examples of such solvents include hydrofluoroether (trade name: Novec7600; manufactured by 3M). Furthermore, in step (v), when removing the first PFPE from the PFA tube, it is preferable to apply ultrasonic waves to the PFA tube in order to promote the removal of the first PFPE from the PFA tube.

[0060] The method for manufacturing a fixing rotor according to one aspect of the present disclosure will be described more specifically. In step (iii), a laminate consisting of a base layer, an elastic layer containing silicone rubber, and a PFA tube having an orientation degree A according to the present disclosure, stacked in this order, is attached to a dipping device. The laminate is then immersed in a bath of perfluoropolyether heated to a temperature T above room temperature and below the melting point Tp (°C) of PFA (e.g., Tp - 100°C ≦ T ≦ Tp - 5°C, preferably Tp - 20°C ≦ T ≦ Tp - 5°C), and left for preferably 20 seconds to 5 minutes, more preferably 30 seconds to 2 minutes (e.g., 1 minute). (Impregnation Step-1) In the impregnation step 1, within the above temperature range, the higher the temperature and the lower the viscosity of the PFPE, the more the amount of PFPE impregnated into the PFA tube can be increased. Furthermore, by contacting the PFA tube at a temperature below the melting point Tp (°C), it is possible to prevent the molecular orientation of the PFA tube from changing before and after step (iii). When the temperature of the first PFPE in the impregnation step-1 is X (°C), X-Tp (°C) is preferably -40°C to 0°C, more preferably -40°C to -5°C, and even more preferably -20°C to -5°C.

[0061] In step (v), the laminate is immersed in a solvent capable of dissolving the first PFPE, and the first PFPE impregnated in the PFA tube is eluted from the openings in the outer surface of the PFA tube (pore forming step).By this step, pores opening on the outer surface of the PFA tube are formed.

[0062] In step (vi), the laminate provided with the porous PFA tube obtained in step (v) is immersed in a bath of the second perfluoropolyether and left for preferably 5 to 30 minutes, more preferably 10 to 20 minutes (e.g., 15 minutes), thereby allowing the second PFPE to be impregnated into the pores in the PFA tube (impregnation step-2). The temperature of the second PFPE in this step is preferably set to a temperature that can promote the impregnation of the second PFPE into the pores and does not cause the openings on the first surface of the PFA tube to disappear. As a non-limiting example, the lower limit of the temperature of the second PFPE in this step is preferably 180°C or higher, and the upper limit is preferably 280°C or lower, more preferably 230°C or lower.

[0063] Then, the laminate obtained through step (vi) is taken out of the second perfluoropolyether bath, and the second PFPE adhering to the outer surface is removed, thereby obtaining a fixing rotor according to one embodiment of the present disclosure. In this step, the method for removing the excess PFPE adhering to the surface is not particularly limited, but examples thereof include washing with a solvent (preferably a fluorine solvent), removing with air, wiping with a nonwoven fabric, etc. Examples of the method for washing with a solvent (preferably a fluorine solvent) include removing with fibers such as a nonwoven fabric impregnated with a solvent (preferably a fluorine solvent).

[0064] 2. Fixing device The fixing device includes a fixing rotor and a heating means for heating the fixing rotor, for example, a heating rotor and a pressure rotor disposed to form a fixing nip with the heating rotor. Examples of combinations of a heating rotor and a pressure rotor include a heating roller and an elastic pressure roller disposed opposite the heating roller, and a fixing belt and an elastic pressure roller disposed in contact with the fixing belt. Another example of a combination of a heating rotor and a pressure rotor is a heating belt and an elastic pressure roller disposed in contact with the heating belt. , a heating belt and an elastic pressure belt arranged in contact with the heating belt, and the like.

[0065] (1) Fixing device using a fixing belt FIG. 3 is a cross-sectional view of a fixing device including a fixing belt 11 for heating and an elastic pressure roller 19, taken along the circumferential direction of the fixing belt. The fixing belt 11 is the fixing belt described above as the fixing rotating body. The fixing belt 11 is loosely fitted around a belt guide member 16. A pressure rigid stay 18 is inserted inside the belt guide member 16. The belt guide member 16 is formed, for example, from a resin having heat resistance and heat insulation properties.

[0066] The heating means is, for example, a heater arranged in contact with the inner circumferential surface of the fixing belt. A ceramic heater 17 is provided as a heat source at the position where the belt guide member 16 and the inner surface of the fixing belt 11 come into contact. The ceramic heater 17 is fitted into and fixed in a groove provided along the longitudinal direction of the belt guide member 16. The ceramic heater 17 generates heat when electricity is applied by means not shown. The elastic pressure roller 19 has an elastic layer 19b made of hardened silicone rubber provided on the circumferential surface of a stainless steel core 19a. A surface layer 19c made of fluororesin is provided on the circumferential surface of the elastic layer 19b. The thickness of the surface layer 19c is, for example, 50 μm.

[0067] Pressure springs (not shown) are respectively compressed between both ends of the pressure rigid stay 18 and spring bearing members (not shown) on the device chassis side, thereby applying a downward force to the pressure rigid stay 18. As a result, the lower surface of the ceramic heater 17 disposed on the lower surface of the belt guide member 16 and the upper surface of the elastic pressure roller 19 are brought into pressure contact with each other, sandwiching the fixing belt 11, to form a predetermined fixing nip N. In other words, the lower surface of the ceramic heater 17 is disposed in contact with the inner circumferential surface of the fixing belt 11. A recording medium P, which is a heated object and on which an image is formed with unfixed toner G, is sandwiched and conveyed through this fixing nip N at a conveying speed V. This heats and pressurizes the toner image. As a result, the toner image melts and mixes colors, and is then cooled to fix the toner image on the recording medium P.

[0068] (2) Thermal fixing device using a fixing roller FIG. 4 is a cross-sectional view taken along the circumferential direction of a fixing roller in a thermal fixing device that includes a fixing roller 12 for heating, an elastic pressure roller 19 arranged opposite the fixing roller 12, and a heater 20 that is a heating means for the fixing roller 12. The fixing roller 12 is the fixing roller described above as a rotating body for fixing. The fixing roller 12 has an elastic layer 14 formed on the outer peripheral surface of a hollow core metal as a base layer 13, and a release surface layer 15 formed on the outer surface thereof.

[0069] The fixing roller 12 and the elastic pressure roller 19 are rotatably pressed against each other by a pressure means (not shown), forming a fixing nip N. A heater 20 is installed inside the fixing roller 12 and the elastic pressure roller 19 as a heat source to supply the heat necessary to melt the unfixed toner G. A halogen heater is generally used as the heater 20. In some cases, multiple halogen heaters are installed inside according to the size of the recording medium P being conveyed.

[0070] A rotational force is applied to the fixing roller 12 and the elastic pressure roller 19 through the base layer (metal core) 13 and the end of the metal core 19a by means not shown, and the rotation is controlled so that the moving speed of the surface of the fixing roller 12 is approximately equal to the conveying speed V of the recording medium P. In this case, the rotational force may be applied to either the fixing roller 12 or the elastic pressure roller 19, and the other may be rotated by being driven, or the rotational force may be applied to both. The recording medium P, which is the heated object on which an image is formed with unfixed toner G, is sandwiched and conveyed through the fixing nip N of the fixing device thus formed. This heats and pressurizes the toner image. As a result, the toner image is melted and mixed, and then cooled, thereby fixing the toner image on the recording medium P.

[0071] 3. Electrophotographic image forming apparatus The electrophotographic image forming apparatus may have a known configuration. Examples include multifunction machines, copiers, fax machines, printers, etc. that use electrophotography. Here, a color laser printer will be used as an example to provide an outline of the overall configuration of an electrophotographic image forming apparatus. Figure 5 is a schematic cross-sectional view of a laser printer 40. The laser printer 40 shown in Figure 5 has an image forming unit having electrophotographic photosensitive drums 39 (hereinafter referred to as "photosensitive drums 39") that rotate at a constant speed for each of the colors yellow (Y), magenta (M), cyan (C), and black (K). The printer also has an intermediate transfer member 38 that holds the color image developed and multiple-transferred in the image forming unit and further transfers it to a recording medium P fed from a feed unit.

[0072] The photosensitive drums 39 (39Y, 39M, 39C, 39K) are driven to rotate counterclockwise as shown in FIG. 5 by a driving means (not shown). Around the photosensitive drum 39, in the direction of rotation, there are arranged, in this order, charging devices 21 (21Y, 21M, 21C, 21K) that uniformly charge the surface of the photosensitive drum 39, scanner units 22 (22Y, 22M, 22C, 22K) that irradiate a laser beam based on image information and form an electrostatic latent image on the photosensitive drum 39, developing units 23 (23Y, 23M, 23C, 23K) that attach toner to the electrostatic latent image and develop it as a toner image, primary transfer rollers 24 (24Y, 24M, 24C, 24K) that transfer the toner image on the photosensitive drum 39 to the intermediate transfer body 38 at the primary transfer portion T1, and cleaning units 25 (25Y, 25M, 25C, 25K) that have cleaning blades that remove residual toner remaining on the surface of the photosensitive drum 39 after transfer.

[0073] During image formation, a belt-like intermediate transfer body 38 stretched over rollers 26, 27, and 28 rotates, and the toner images of each color formed on each photosensitive drum 39 are superimposed and transferred onto the intermediate transfer body 38 as a primary transfer, thereby forming a color image. The recording medium P is conveyed to the secondary transfer portion T2 by a conveying means so as to be synchronized with the primary transfer onto the intermediate transfer body 38. The conveying means has a feeding cassette 29 storing a plurality of recording media P, a feeding roller 30, a separation pad 31, and a pair of registration rollers 32. During image formation, the feeding roller 30 is driven to rotate in accordance with the image forming operation, separating the recording media P in the feeding cassette 29 one by one, and conveying the recording media P to the secondary transfer portion T2 by the pair of registration rollers 32 in synchronization with the image forming operation.

[0074] A movable secondary transfer roller 33 is disposed at the secondary transfer portion T2. ​​The secondary transfer roller 33 is movable in a substantially vertical direction. During image transfer, the secondary transfer roller 33 is pressed against the intermediate transfer body 38 with a predetermined pressure via the recording medium P. At the same time, a bias is applied to the secondary transfer roller 33, and the toner image on the intermediate transfer body 38 is transferred to the recording medium P. Because the intermediate transfer body 38 and the secondary transfer roller 33 are both driven, the recording medium P sandwiched between them is conveyed in the direction of the left arrow shown in FIG. 5 at a predetermined conveying speed V, and is then conveyed by a conveyor belt 34 to the next process, a fixing unit 35. In the fixing unit 35, heat and pressure are applied to fix the transferred toner image onto the recording medium P. The recording medium P is then discharged onto a discharge tray 37 on the top surface of the device by a pair of discharge rollers 36. By applying the fixing devices illustrated in Figures 3 and 4 to the fixing section 35 of the electrophotographic image forming apparatus illustrated in Figure 5, an image forming apparatus can be obtained that can provide high-quality images with excellent image uniformity.

[0075] According to one aspect of the present disclosure, a fixing rotator can be obtained that can maintain high toner releasability for a longer period than conventionally possible and that can maintain abrasion resistance against paper. According to another aspect of the present disclosure, a fixing device and an electrophotographic image forming apparatus that contribute to the stable formation of high-quality electrophotographic images can be obtained. Furthermore, according to another aspect of the present disclosure, a manufacturing method for a fixing rotator can be obtained that can maintain high toner releasability for a longer period than conventionally possible and that can maintain abrasion resistance against paper. [Example]

[0076] The present disclosure will be specifically described below using examples, but the present disclosure is not limited to the following examples.

[0077] In this example, the fixing rotor was produced using the following PFA resin and perfluoropolyether: Specifically, the perfluoropolyether used had at least one structure selected from the group consisting of the above formulas (2) to (5). (Fluorine resin) PFA-1: "959HP-Plus" (product name, manufactured by Mitsui-Chemours Fluoroproducts) (perfluoropolyether) PFPE-1: "Krytox GPL103" (trade name, manufactured by Chemours, 54 mPa·s (40°C)) PFPE-2: "Krytox GPL104" (trade name, manufactured by Chemours, 111 mPa·s (40°C)) PFPE-3: "Krytox VPF16256" (trade name, manufactured by Chemours, 1403 mPa·s (40°C)) PFPE-4: "Krytox XHT-1000" (product name, manufactured by Chemours, 1941 mPa·s (40°C)) PFPE-5: "Fomblin M100" (product name, manufactured by Solvay, 1327 mPa·s (40°C)) PFPE-6: "Krytox GPL106" (trade name, manufactured by Chemours, 459 mPa·s (40°C))

[0078] Example 1 (Production of fixing belt) As the base layer, a substrate having an endless belt shape made of electroformed nickel with an inner diameter of 30 mm, a width of 400 mm, and a thickness of 40 μm was prepared. The outer peripheral surface of this substrate was treated with a primer. The raw material for forming the elastic layer was an addition-curing liquid silicone rubber (product name: SE1886, manufactured by Dow Corning Toray Co., Ltd.) containing no filler. To 61 parts by volume of this liquid silicone rubber, 38 parts by volume of spherical alumina (product name: Alnabeads CB-A30S, manufactured by Showa Denko K.K.) was added as a spherical filler, and 1 part by volume of vapor-grown carbon fiber (product name: VGCF-S, manufactured by Showa Denko K.K., aspect ratio = 100, average fiber length = 10 μm) was added as an irregular-shaped filler.

[0079] The addition-curable silicone rubber composition for forming the elastic layer was prepared in this way and applied to the outer peripheral surface of the substrate by ring coating, followed by heating at 200°C for 4 hours to crosslink the layer of addition-curable silicone rubber composition and form an elastic layer 300 μm thick. The substrate on which the elastic layer was formed was rotated in the circumferential direction at a moving speed of 20 mm / sec, and the surface of the elastic layer was irradiated with ultraviolet light in an atmospheric environment using an ultraviolet lamp positioned at a distance of 10 mm from the surface of the elastic layer. As the ultraviolet lamp, a low-pressure mercury ultraviolet lamp (product name: GLQ500US / 11, manufactured by Toshiba Lighting & Technology Corporation) was used, and the irradiation surface was irradiated with ultraviolet light of 185 n The cumulative light intensity of a wavelength of 800 mJ / cm 2 The irradiation was carried out so that

[0080] Next, an addition-curing silicone rubber adhesive (product name: SE1819CV, a mixture of equal amounts of "liquid A" and "liquid B" manufactured by Dow Corning Toray Co., Ltd.) was applied uniformly to the surface of the elastic layer to a thickness of approximately 20 μm. Furthermore, PFA-1 melted at a temperature of 360°C was extruded into a cylinder to produce a PFA tube (thickness: 20 μm, melting point: Tp = 296°C) with an orientation degree A of 35%. After the inner surface of this PFA tube was hydrophilically treated, the PFA tube was placed over the surface of the elastic layer coated with the addition-curing silicone rubber adhesive, and the PFA tube was uniformly squeezed from above to squeeze out excess adhesive from between the elastic layer and the fluororesin tube. The elastic layer and the base layer covered with the PFA tube were then placed in an electric furnace set at a temperature of 200°C and heated for 1 hour to harden the addition-curing silicone rubber adhesive and fix the fluororesin tube onto the elastic layer. Both ends were then cut to obtain a laminate for a fixing belt 343 mm wide.

[0081] (Preparation of fixing belt: Contact impregnation of perfluoropolyether) (Impregnation process-1) Perfluoropolyether (PFPE-1) was placed in a measuring cylinder made of borosilicate glass. The measuring cylinder was completely wrapped with a heating wire covered with a heat insulating material and heated to a PFPE temperature of 280°C. The prepared fixing belt was attached to a dipping device, and the laminate was immersed in the heated first PFPE for 1 minute and then removed.

[0082] <Evaluation A-1: ​​Measurement of the content of the first PFPE in the PFA tube containing the first PFPE> The content of the first PFPE in the obtained PFA tube impregnated with the first PFPE was measured by the following method. That is, a laminated sample of an elastic layer and a PFA tube was cut out from the laminate. Next, the laminated sample was immersed in a silicone resin dissolving agent (trade name: e-solv 21RS, manufactured by Kaneko Chemical Co., Ltd.) to dissolve the silicone rubber and silicone rubber adhesive in the elastic layer, thereby removing the elastic layer and adhesive layer from the laminated sample. In this way, a measurement sample consisting only of the entire thickness of the PFA tube was prepared. This measurement sample was measured using a thermogravimetric analyzer (TGA) under the following conditions, and the content (mass%) of the first PFPE relative to the resin layer containing the first PFPE was calculated. Apparatus: TGA851 (trade name, manufactured by METTLER TOLEDO) Atmosphere: In air Temperature: 425℃ In the profile of measurement time-weight loss rate obtained by the above-mentioned thermogravimetric analysis, the slope becomes constant and the linear least squares approximation formula is obtained from the region where only PFA decreases.Then, the intercept of this linear least squares approximation formula is set as PFA content (mass%), and the first PFPE content (mass%) is calculated as 100-PFA content.

[0083] (Vacancy formation process) The laminate obtained in the above impregnation step-1 was immersed for 10 minutes in a measuring cylinder containing a fluorine solvent (trade name: Novec 7300, manufactured by 3M). The measuring cylinder was then placed in the water tank of an ultrasonic cleaning device (trade name: Bransonic (model 2510J-DTH); manufactured by Emerson Japan Co., Ltd.), and ultrasonic waves were applied for 60 minutes. After treatment, the laminate was removed from the measuring cylinder and left to dry in an environment at 25°C for 60 minutes. In this way, a laminate was obtained from which the PFPE present on the outer surface and inside of the PFA tube had been removed. The obtained laminate had a white appearance when visually inspected, confirming that pores had been formed in the PFA tube. 1(A) and 1(B) are schematic diagrams of scanning electron microscope images of the outer surface (first surface) of the PFA tube of the obtained laminate and a cross section of the laminate in the circumferential direction. FIG. 1(A) is a schematic diagram of an SEM image of the first surface. A resin portion 1 containing PFA and an opening 2 were observed. FIG. 1(B) is a schematic diagram of an SEM image of a cross section in the thickness direction of the PFA tube along the circumferential direction of the laminate. A resin portion 1 containing PFA and pores 3 were observed. It was also observed that the pores 3 opened to the first surface 101, and had openings on the first surface.

[0084] <Evaluation A-2: Measurement and Calculation of Opening Ratio P1, Average Opening Diameter, and Porosity P2 on the First Surface of the PFA Tube> The opening ratio P1 and the average opening diameter on the first surface of the PFA tube were calculated as follows. The surface of the laminate obtained in the above-mentioned pore forming step from which the first PFPE had been removed, i.e., the surface opposite to the side facing the elastic layer of the PFA tube, was observed with a scanning electron microscope, and an SEM image (magnification 10,000 times) of a rectangular observation area measuring 8 μm in length and 11 μm in width was obtained. The resolution was set to 717 pixels vertically and 986 pixels horizontally to allow the apertures to be clearly identified. The acquired SEM images were converted to 8-bit grayscale images using image processing software (Image-J, manufactured by the National Institutes of Health, USA). A median filter was applied to the resulting grayscale image, and then binarized using the image processing software to obtain a binary image. The binarization process used the YEN method (see IEEE Transactions on Image Processing, Vol. 4, Issue 3, March 1995, pp. 370-378) to distinguish between the portions corresponding to the apertures and the portions corresponding to the PFA in the SEM image. The ratio of the number of pixels corresponding to the apertures in the resulting binary image to the number of pixels in the entire image was calculated. Ten observation regions were randomly placed on the first surface of the PFA tube, and the arithmetic mean of the ratios calculated from each observation region was defined as the aperture ratio P1. The observation regions were positioned so that they did not overlap each other. The area of ​​the portion corresponding to the opening in each binarized image was approximated by a perfect circle of the same area, and the average opening diameter was calculated as the arithmetic mean value of the diameters of the perfect circles (hereinafter referred to as the circle equivalent diameter).

[0085] The porosity P2 was calculated as follows. A cross-sectional sample showing a cross section of the PFA tube in the thickness direction along the circumferential direction of the laminate was cut out from the PFA tube of the laminate from which the first PFPE had been removed using a cryo-ultramicrotome (manufactured by Leica Microsystems). The cross section included the entire thickness of the resin layer.

[0086] Next, the cross section was observed using a scanning electron microscope, and an SEM image of an observation area measuring 8 μm in length and 11 μm in width was obtained. The resolution was set to 717 pixels in length and 986 pixels in width so that voids appearing in the cross section could be recognized. The obtained SEM image was binarized using numerical calculation software (product name: MATLAB (registered trademark), manufactured by MathWorks) to obtain a binarized image. The binarization process was carried out using Otsu's method (IEEE TRANSACTIONS ON SYSTEMS, MAN, AND CYBERNETICS, VOL. 10, 2009) in order to distinguish between the parts corresponding to voids and the parts corresponding to PFA in the SEM image. SMC-9, No. 1, January 1979, pp. 62-66) was used.

[0087] The ratio of the number of pixels in the portion corresponding to the voids in the binarized image to the number of pixels in the entire image was calculated. The SEM images were taken at three positions in the thickness direction of the cross section of the cross-sectional sample, as specified in the following (i) to (iii). (i) In the cross section of the cross-sectional sample, the upper end of the observation area is 1 μm from the first surface of the PFA tube toward the other surface (hereinafter also referred to as the "second surface"), and the long side of the observation area is parallel to the first surface. (ii) A position in the cross section of the cross-sectional sample where the midpoint between the first surface and the second surface of the PFA tube coincides with the center of gravity of the observation area, and the long side of the observation area is parallel to the first surface. (iii) In the cross section of the cross-sectional sample, the lower end of the observation area is 1 μm from the second surface of the PFA tube toward the first surface, and the long side of the observation area is parallel to the second surface. Furthermore, cross-sectional samples were cut out from three locations at 120° intervals in the circumferential direction of the laminate. Therefore, a total of nine SEM images were obtained by the above operation, and nine ratios were calculated based on the binarized images created from each SEM image. The arithmetic mean value of these nine ratios was taken as the porosity P2.

[0088] (Impregnation process-2) Next, the laminate provided with the PFA tube having holes, obtained through the above-mentioned hole-forming step, was subjected to the following operation: That is, the second PFPE (PFPE-3) was placed in a borosilicate glass measuring cylinder. The measuring cylinder was entirely wrapped with a heating wire covered with an insulating material, and the second PFPE was heated to 200° C. Next, the laminate was attached to a dipping device, and the entire laminate was immersed in a second PFPE bath at 200° C. for 15 minutes and then removed. Next, the second PFPE adhering to the outer surface of the removed laminate was removed using a nonwoven fabric impregnated with a fluorine-based solvent (product name: Novec 7300; manufactured by 3M). Thus, a fixing belt according to this example was obtained. A schematic image of a cross section of the surface layer of the obtained fixing belt in the circumferential direction, observed with a scanning electron microscope, is shown in FIG. 1(C). It was confirmed that the pores 3 observed in FIG. 1(B) were filled with the second PFPE 4 in the impregnation step 2.

[0089] <Evaluation A-3: Measurement of the content of the second PFPE in the surface layer> A measurement sample consisting of only the entire thickness of the PFA tube was prepared for the obtained fixing belt in the same manner as in Evaluation A-1. This measurement sample was measured using a thermogravimetric analyzer (TGA) under the following conditions, and the content ratio (mass %) of the second PFPE in the surface layer relative to the total mass of the surface layer, including the mass of the second PFPE in the pores, was calculated. Apparatus: TGA851 (trade name, manufactured by METTLER TOLEDO). Atmosphere: Air ·Temperature: 425℃ In the profile of measurement time versus weight loss rate obtained by the thermogravimetric analysis, a linear least-squares approximation was calculated from the region where the slope was constant and only PFA was decreasing. The intercept of the linear least-squares approximation was taken as the PFA content (% by mass), and the content of the second PFA was calculated as 100 - PFA content.

[0090] <Evaluation as a fixing belt> The obtained fixing belt was subjected to the following evaluations B-1 to B-4.

[0091] (Evaluation B-1: Measurement of the degree of orientation A of the surface layer of the fixing belt) Using the same method as in Evaluation A-1, only the PFA tube containing the second PFPE was removed from the fixing belt. This PFA tube was cut along the MD direction and opened to obtain a sheet-shaped analytical sample. This analytical sample was analyzed using an X-ray diffraction (XRD) device using the θ-2θ method.

[0092] Specifically, a rotating sample stage was first attached to an X-ray diffraction instrument (product name: RINT2500; manufactured by Rigaku Corporation). Then, the sample attachment with the above-mentioned analysis sample attached was rotated. The measurement conditions were as follows: Device: RINT 2500 (product name, manufactured by Rigaku Corporation) X-ray source:CuKα Detector: Scintillation counter Attachment: Rotating sample stage Voltage: 40kV Current: 15mA Slit conditions: DS (divergence slit) = 0.625°, SS (scatter slit) = 1.25°, RS (receiving slit) = 0.3 mm Measurement mode: β rotation, 2θ fixed (2θ=18°), θ fixed (transmission method)

[0093] The orientation measurement was performed over a 360-degree in-plane rotation (β rotation) of the measurement sample. The sample was also positioned so that the starting point of the β rotation (0 degrees) coincided with the transverse direction (TD) measurement direction of the surface layer. This resulted in diffraction peaks at β rotation angles of 90° and 270°, which were attributable to PFA molecules oriented in the MD of the measurement sample. The sample was then beta-rotated to obtain a diffraction chart showing the intensity of the diffraction peak for each angle of beta rotation (see Figure 6). From the half-width (W) of the peaks in the diffraction chart with tops at beta rotation angles of 90 and 270 degrees, the degree of orientation A (%), which represents the degree of MD orientation of the PFA molecules, was calculated using the following formula (1): A = [(360-ΣW) / 360] × 100(%) (1) The half-width W is defined as the width of the peak at a position half the height h from the baseline of the peak top at β rotation angles of 90° and 270°, where the baseline shown by the dotted line in FIG. 6 is drawn.

[0094] The obtained fixing belt was subjected to the following evaluations. (Evaluation B-2: Evaluation of the Presence or Absence of Toner Offset) The fixing belt was mounted on an electrophotographic image forming apparatus (product name: imageRUNNER-ADVANCE C5051; manufactured by Canon Inc.) in which the angle of the paper separation claws had been adjusted. Then, A4 size paper (manufactured by International Paper, basis weight 75 g / m 2 An image formation process was carried out to form a 10 cm x 10 cm solid cyan image on a sheet of paper. The fixing temperature was 180°C and the paper transport speed was 300 mm / sec. Then, when the number of sheets on which a cyan solid image was formed reached 1, 300,000, and 600,000, an A4-sized thin plain paper (product name: CS-520, basis weight 52 g / m) was used. 2 A sheet of a Canon (Canon Inc.) was passed through the paper to form a 10 cm x 10 cm solid image of cyan color. The solid image formed on the thin plain paper was observed visually and under a microscope and evaluated according to the following criteria. (Evaluation criteria) Rank A: Neither toner offset nor toner missing occurs. Rank B: Toner offset and slight toner loss are observed. Rank C: Both toner offset and toner loss are observed. Rank D: Plain paper Thin paper stuck to the fixing belt.

[0095] (Evaluation B-3: Measurement of surface free energy) In Evaluation 2, the surface free energy of the outer surface of the fixing belt immediately before forming a solid image on each piece of plain paper or thin paper was calculated using the "Kitazaki-Hata method" described in Non-Patent Document 1. Specifically, the contact angles of water, n-hexadecane, and diiodomethane were measured on the outer surface of the fixing belt (measurement environment: temperature 23°C, relative humidity 55%). Next, using the measurement results of each contact angle, the surface free energy was calculated from the "extended Fowkes equation" according to the theory of Kitazaki and Hata (Non-Patent Document 1). A contact angle meter (trade name: DM-501, manufactured by Kyowa Interface Science Co., Ltd.) was used for the measurement, and analytical software (trade name: FAMAS, manufactured by Kyowa Interface Science Co., Ltd.) was used for the surface free energy analysis.

[0096] (Evaluation B-4: Evaluation of surface layer abrasion resistance against paper) The fixing belt was mounted on an electrophotographic image forming apparatus (product name: imageRUNNER-ADVANCE C5051, manufactured by Canon Inc.). Then, A5 size paper (International Paper, basis weight 75 g / m 2 An image formation process was carried out to form a black grid image on a paper sheet (210 mm wide, 210 mm deep) at a fixing temperature of 180°C and a paper transport speed of 300 mm / sec. At the time when the number of images formed reached 100,000, 200,000, and 300,000, A4 size paper (manufactured by International Paper Co., 75 g / m²) was used. 2 A single sheet of paper (294 mm in width and depth) was passed through the printer to form a solid image in cyan. The solid image formed on the thin plain paper was observed visually and under a microscope, and the portion located at the edge of the A5 size paper was evaluated according to the following criteria. (Evaluation criteria) Rank A: No toner offset after 300,000 or more sheets. Rank B: A small amount of toner offset was detected at 200,000 sheets. Rank C: Toner offset is confirmed at 100,000 sheets. Rank D: Toner offset is confirmed after 100,000 sheets or less Toner offset in this evaluation indicates that the surface layer of A5 size paper wears away at the edges as it passes through, and as the edges become more worn away, toner gets stuck in, causing gradual offset. When the surface layer is completely worn away, the toner adheres completely to the fixing belt.

[0097] Examples 2 to 9 The degree of orientation A of the PFA tube used to form the surface layer, the temperature at the time of contact with the first PFPE in the impregnation step-1, the type of the second PFPE used in the impregnation step-2, and the temperature at the time of contact with the second PFPE in the impregnation step-2 were changed as shown in Table 1. Fixing belts Nos. 2 to 9 according to each example were produced in the same manner as in Example 1 except for the changes. The PFA tubes prepared in Examples 2 and 6 to 9 with an orientation degree A of 55% were produced in the same manner as in Example 1, except that the temperature during melt extrusion of PFA was set to 370°C. The PFA tubes prepared in Examples 3 and 5 with an orientation degree A of 75% were produced in the same manner as in Example 1, except that the temperature during melt extrusion of PFA was set to 390°C. The physical properties (P1, P2, average opening diameter) of the PFA tube having voids obtained by the impregnation step-1 and the removal step, and the second PFPE content in the surface layer obtained by the impregnation step-2, in which the second PFPE had been introduced into the voids, were measured and calculated in the same manner as in Evaluations A-1 to A-3 of Example 1. The results are shown in Table 1. Fixing belts Nos. 2 to 9 were each subjected to evaluations B-1 to B-4 described in Example 1. The evaluation results are shown in Table 2.

[0098] (Comparative Example 1) Fixing belt No. C-1 was obtained in the same manner as in Example 9, except that in the impregnation step-2, the temperature during contact with the second PFPE was set as shown in Table 1. The content of the second PFPE in the surface layer of the obtained fixing belt No. C-1 was measured and calculated in the same manner as in Evaluation A-3 of Example 1. The results are shown in Table 1. In addition, the evaluation results of Evaluations B-1 to B-4 for fixing belt No. C-1 are shown in Table 2. In the fixing belt C-1 according to this comparative example, the introduction of the second PFPE into the voids in the impregnation step-2 was insufficient, and therefore a decrease in the toner releasability of the first surface of the surface layer over time was observed.

[0099] (Comparative Example 2) The type of the first PFPE and the temperature during contact in the impregnation step-1 were as shown in Table 1. Other than that, the steps up to the first PFPE removal step were carried out in the same manner as in Example 1, to produce a laminate in which the outer peripheral surface of the elastic layer was covered with a PFA resin tube having voids. This was designated fixing belt No. C-2 in this comparative example. The content of the first PFPE in the first PFPE-containing PFA tube obtained by impregnation step-1, and the physical properties (P1, P2, average opening diameter) of the PFA tube having voids obtained by impregnation step-1 and the removal step were measured and calculated in the same manner as in Evaluations A-1 and A-2 in Example 1. The results are shown in Table 1.

[0100] The results of evaluations B-1 to B-4 for fixing belt No. C-2 are shown in Table 2. As shown in Table 2, fixing belt No. C-2 had a surface layer orientation degree A of 0%. This is thought to be because the temperature at the time of contact between the PFA tube and the first PFPE in impregnation step-1 was 300°C, which is higher than the melting point of PFA-1, and therefore the MD orientation of the PFA molecules in the PFA tube was lost. Furthermore, fixing belt No. C-2 had poor abrasion resistance on the first surface because the PFA molecules in the surface layer were not MD-oriented. Furthermore, because the second PFPE was not introduced into the voids, the toner release property of the first surface was low from the beginning.

[0101] (Comparative Example 3) The type of the first PFPE used in the impregnation step-1 and the temperature at the time of contact in the impregnation step-1 were as shown in Table 1. Other than that, the operations up to the impregnation step-1 were carried out in the same manner as in Comparative Example 2. Furthermore, the first PFPE adhering to the surface of the laminate obtained through the impregnation step-1 was wiped off and removed with a nonwoven fabric. The laminate obtained in this manner was designated as fixing belt No. C-3 according to this comparative example. The content of the first PFPE in the first PFPE-containing PFA tube obtained by impregnation step-1 was measured and calculated in the same manner as in Evaluation A-1 described in Example 1. The results are shown in Table 1.

[0102] In addition, in fixing belt No. C-3, even after the first PFPE removal step, no voids were formed in the surface layer. This is thought to be because the amount of the first PFPE impregnated into the PFA tube in the impregnation step-1 was insufficient to form aggregates of the first PFPE within the PFA tube. The results of evaluations B-1 to B-4 for fixing belt No. C-3 are shown in Table 2. As in Comparative Example 2, the temperature at the time of contact in impregnation step-1 was higher than the melting point of PFA-1, so the degree of orientation A of the PFA molecules in the surface layer was 0%. Furthermore, because the PFA molecules were not oriented in the MD, the abrasion resistance of the first surface of the surface layer was poor. Furthermore, because the amount of PFPE contained in the surface layer was small, a decrease in the toner release property of the first surface over time was observed.

[0103] Comparative Example 4 A laminate was produced in the same manner as in Comparative Example 3, except that the PFA tube used in Example 2, which had an orientation degree A of 55%, was used as the PFA tube, and the temperature at the time of contact in the impregnation step-1 was set as shown in Table 1. This was designated fixing belt No. C-4 according to Comparative Example 4. The content of the first PFPE in the first PFPE-containing PFA tube obtained by impregnation step-1 was measured and calculated in the same manner as in Evaluation A-1 in Example 1. The results are shown in Table 1.

[0104] As with the fixing belt No. C-3, the fixing belt No. C-4 is also Even when the PFPE removal step was performed, no voids could be formed in the surface layer. This is thought to be because the amount of the first PFPE impregnated into the PFA tube in the impregnation step-1 was insufficient to form aggregates of the first PFPE within the PFA tube. The results of evaluations B-1 to B-4 for fixing belt No. C-4 are shown in Table 2. Because the temperature at the time of contact in impregnation step-1 was lower than the melting point of PFA-1, the orientation degree A of the PFA molecules in the surface layer was 55%, maintaining the orientation degree A of the PFA tube. Therefore, the first surface of the surface layer had excellent abrasion resistance. On the other hand, since the content of PFPE in the surface layer was low, a decrease in the toner releasability of the first surface was observed over time.

[0105] (Comparative Example 5) A PFA tube having an orientation degree A of 85% was produced in the same manner as in Example 1, except that the temperature during melt extrusion of PFA was 400° C. Fixing belt No. C-5 was produced in the same manner as in Example 8, except that this PFA tube was used. The content of the first PFPE in the first PFPE-containing PFA tube obtained by impregnation step-1, the physical properties (P1, P2, average opening diameter) of the PFA tube having voids obtained by impregnation step-1 and the removal step, and the content of the second PFPE in the surface layer of fixing belt No. C-5 were measured and calculated in the same manner as in Evaluations A-1 to A-3 described in Example 1. The results are shown in Table 1.

[0106] Furthermore, fixing belt No. C-5 was subjected to evaluations B-1 to B-4. From the results of evaluation 1, the orientation degree A of the surface layer of fixing belt No. C-5 was 85%, the same as the orientation degree A of the PFA tube. This is thought to be because the temperature at the time of contact between the PFA tube and the first PFPE in impregnation step-1 was lower than the melting point of PFA-1, so the MD orientation of the PFA molecules in the PFA tube was maintained. Furthermore, for evaluations 2 and 3, tearing occurred in the surface layer along the MD before printing 300,000 solid cyan images. Therefore, evaluations were not performed after 300,000 sheets were printed. For evaluation 4, tearing occurred in the surface layer along the MD during the abrasion resistance evaluation test, so evaluation was discontinued. This is thought to be due to the PFA molecules in the surface layer being too strongly oriented in the MD.

[0107] (Comparative Example 6) Instead of the cylindrically extruded PFA tube, the outer surface of the elastic layer was covered with an expanded porous PTFE membrane (product name: Poreflon HP-010-30, manufactured by Sumitomo Electric Fine Polymer, Inc.) The physical properties (P1, P2 and average opening diameter) of this expanded porous PTFE membrane were measured and calculated in the same manner as in Evaluations A-1 to A-2 of Example 1. Next, this laminate was subjected to the impregnation step-2 in the same manner as in Example 8 to impregnate the second PFPE into the pores of the expanded porous PTFE membrane. Thus, a laminate having the resulting expanded porous PTFE membrane containing the second PFPE as a surface layer was obtained. This was designated as fixing belt No. C-6 according to this comparative example. The content of the second PFPE in the surface layer containing the second PFPE was measured and calculated in the same manner as in Evaluation A-3 of Example 1. In addition, fixing belt No. C-6 was subjected to Evaluations B-2 to B-4. The results are shown in Table 2.

[0108] [Table 1]

[0109] Table 2 shows the evaluation results of the fixing belts produced in Examples 1 to 9 and Comparative Examples 1 to 6.

[0110] [Table 2] [Explanation of symbols]

[0111] 1: resin portion containing PFA, 2: opening, 3: void, 4: PFPE, 101: first surface< / pfa>

Claims

1. A fixing rotating body having a base layer, an elastic layer, and a surface layer in this order, the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether; the surface layer has pores that open to a first surface that constitutes the outer surface of the fixing rotor, At least a portion of the pores contain the perfluoropolyether; the content of the perfluoropolyether in the surface layer is 20% by mass to 60% by mass, The degree of orientation A of the tetrafluoroethylene-perfluoroalkyl vinyl ether molecules in the direction perpendicular to the circumferential direction of the surface layer is 35 to 75%. A fixing rotating body characterized by:

2. a first observation region having a length of 8 μm and a width of 11 μm is placed on a first surface of the surface layer from which the perfluoropolyether in the pores has been removed, and a ratio of the sum of the areas of the openings observed in the first observation region to the area of ​​the first observation region is defined as P1; A second observation region measuring 8 μm in length and 11 μm in width was placed on a cross section of the surface layer from which the perfluoropolyether in the pores had been removed, the cross section including the entire thickness of the surface layer along the circumferential direction of the fixing rotor, and when the ratio of the sum of the areas of the pores observed in the second observation region to the area of ​​the second observation region was defined as P2, 2. The fixing rotating member according to claim 1, wherein P2 / P1 is 1.3 or more.

3. 3. The fixing rotating member according to claim 2, wherein the P2 / P1 ratio is 5.0 or more.

4. 4. The fixing rotating member according to claim 2, wherein the P2 / P1 ratio is 20.0 or less.

5. 5. The fixing rotator according to claim 1, wherein the openings in the outer surface of the surface layer have an average opening diameter of 1 nm or more and 5 μm or less.

6. 6. The fixing rotating member according to claim 1, wherein the surface layer has a thickness of 12 μm or more and 100 μm or less.

7. The fixing rotating member according to any one of claims 1 to 6, wherein the perfluoropolyether has a structure represented by the following formula (1): 【Chemical 1】 (In formula (1), a, b, c, d, e, and f each independently represent 0 or a positive integer, satisfy the relationship 1≦a+b+c+d+e+f≦600, and at least one of a, b, c, and d represents a positive integer.)

8. The fixing rotating member according to any one of claims 1 to 5, wherein the perfluoropolyether has at least one structure selected from the group consisting of the following formulas (2) to (5): 【Chemistry 2】 【change】 【change】 【change】 (In formula (2), n is a positive number, and n is a number in a range that makes the viscosity of PFPE at a temperature of 40°C range from 30 mPa s to 500 mPa s, In formula (3), n′ is a positive number, and n′ is a number in a range that makes the viscosity of PFPE at a temperature of 40° C. fall within the range of 10 mPa s to 2500 mPa s, In formula (4), n" and m are each independently a positive number, m / n" is a number that is 0.5 or more and 2 or less, and n"+m is a number that causes the viscosity of PFPE at a temperature of 40°C to be in the range of 20 mPa s to 1400 mPa s, In formula (5), n''' and m' are each independent positive numbers, m' / n''' is a number that is 20 or greater and 1000 or less, and n'''+m' is a number that causes the viscosity of PFPE at a temperature of 40°C to fall within the range of 20 mPa·s to 1200 mPa·s.

9. 9. The fixing rotor according to claim 1, wherein the fixing rotor is a fixing belt having an endless belt shape.

10. A fixing device comprising a fixing rotor and a heating unit for heating the fixing rotor, the fixing rotating body has a base layer, an elastic layer, and a surface layer in this order; the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether; the surface layer has pores that open to a first surface that constitutes the outer surface of the fixing rotor, At least a portion of the pores contain the perfluoropolyether; the content of the perfluoropolyether in the surface layer is 20% by mass to 60% by mass, the degree of orientation A of the tetrafluoroethylene-perfluoroalkyl vinyl ether molecules in a direction perpendicular to the circumferential direction of the surface layer is 35 to 75%; A fixing device characterized by:

11. the fixing rotating body is a fixing belt having an endless belt shape, 11. The fixing device according to claim 10, wherein the heating means is a heater disposed in contact with the inner circumferential surface of the fixing belt.

12. An electrophotographic image forming apparatus including a fixing device, the fixing device includes a fixing rotor and a heating means for heating the fixing rotor, the fixing rotating body has a base layer, an elastic layer, and a surface layer in this order; the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether; the surface layer has pores that open to a first surface that constitutes the outer surface of the fixing rotor, At least a portion of the pores contain the perfluoropolyether; the content of the perfluoropolyether in the surface layer is 20% by mass to 60% by mass, the degree of orientation A of the tetrafluoroethylene-perfluoroalkyl vinyl ether molecules in a direction perpendicular to the circumferential direction of the surface layer is 35 to 75%; An electrophotographic image forming apparatus comprising:

13. A method for manufacturing a fixing rotating body, comprising: the fixing rotor has a base layer, an elastic layer, and a surface layer in this order, the surface layer containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and a perfluoropolyether, the surface layer has pores opening to a first surface constituting the outer surface of the fixing rotor, at least a portion of the pores containing the perfluoropolyether, and the content of the perfluoropolyether in the surface layer is 20% by mass to 60% by mass; the degree of orientation A of the tetrafluoroethylene-perfluoroalkyl vinyl ether molecules in the direction perpendicular to the circumferential direction of the surface layer is 35 to 75%, The manufacturing method comprises: (i) preparing a resin tube containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, wherein the degree of molecular orientation A of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer is 35 to 75%; (ii) preparing a laminate having a base layer having an endless belt shape or a roller shape, an elastic layer on the outer peripheral surface of the base layer, and the resin tube on the outer peripheral surface of the elastic layer; (iii) a step of immersing the laminate in a first perfluoropolyether heated to a temperature of 25°C or higher but lower than Tp (°C), where Tp is the melting point of the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, to impregnate the resin tube with the perfluoropolyether; (iv) a step of removing at least a portion of the perfluoropolyether in the resin tube of the laminate obtained in the step (iii) using a solvent to form pores in the resin tube that are open to the outer peripheral surface of the resin tube; and (v) containing a second perfluoropolyether in at least a portion of the pores; obtaining a fixing rotor having a surface layer containing the second perfluoropolyether in at least some of the pores; A method for manufacturing a fixing rotating body, comprising:

14. 14. The method for manufacturing a fixing rotator according to claim 13, wherein the viscosity of the first perfluoropolyether at a temperature of 40° C. is 10 mPa·s to 350 mPa·s.

15. 15. The method for manufacturing a fixing rotating member according to claim 13, wherein the solvent dissolves the first perfluoropolyether but does not dissolve the tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.

16. The method for manufacturing a fixing rotator according to any one of claims 13 to 15, wherein the second perfluoropolyether has a viscosity of 300 mPa·s to 2500 mPa·s at a temperature of 40°C.

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