Fixing member and manufacturing method thereof, fixing device, and electrophotographic image forming apparatus

Abstract

To provide a fixing member that can achieve both of toner releasing properties and scratch resistance at a high level over a long period of time.SOLUTION: A fixing member having an endless belt shape or a roller shape includes a base layer and a surface layer. The surface layer contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, and has a pore communicating with an opening of an outer surface of the surface layer, and perfluoropolyether is contained in at least a part of the pore. A ratio (E"(1) / E"(2)) is 0.60 or more and less than 1.00, where E"(1) is an average value of loss elastic moduli E" of the surface layer in a direction orthogonal to a circumferential direction of the fixing member measured at a frequency of 10 Hz at 100 to 150°C, and E"(2) is an average value of loss elastic moduli E" of the surface layer in the direction orthogonal to the circumferential direction of the fixing member measured at the frequency of 10 Hz at 100 to 150°C after removal of the perfluoropolyether contained in the pore.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In a fixing device used in an electrophotographic image forming apparatus (hereinafter also referred to as an "image forming apparatus"), two rotating bodies, such as a pair of heated rollers, a film and a roller, a belt and a belt, or a belt, are in pressure contact with each other. These rotating bodies are called fixing members. A recording medium 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 is 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, with conventional fixing members, melted toner adheres to the surface of the fixing member (rotating body) during thermal fixing, and the thin paper sometimes wraps around the fixing member. In order to stably form electrophotographic images on thin paper, it is effective to impart higher toner releasability to the surface of the fixing member. Patent Document 1 discloses a fixing member whose surface layer contains a fluororesin and a fluorinated oil having a perfluoropolyether (hereinafter also referred to as "PFPE") structure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-140185 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors have conducted extensive research into the fixing member disclosed in Patent Document 1 in order to provide a fixing member with excellent toner releasability over a long period of time. In the process, the present inventors have discovered a new problem that has not yet been solved by the fixing member provided with the surface layer disclosed in Patent Document 1. That is, with the fixing member disclosed in Patent Document 1, scratches may occur on the outer surface of the surface layer in the area where the edge of the paper comes into contact after long-term use.

[0005] One aspect of the present disclosure is to provide a fixing member that can achieve both high levels of toner releasability and scratch resistance over a long period of time. Another aspect of the present disclosure is to provide a fixing device and an electrophotographic image forming apparatus that can stably form high-quality electrophotographic images over a long period of time. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a fixing member having an endless belt shape or a roller shape, the fixing member having a base layer and a surface layer, the surface layer containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and having pores that connect to openings in the outer surface, at least some of the pores containing perfluoropolyether, wherein E''(1) is the average value of the loss modulus E'' of the surface layer measured at a temperature of 100°C to 150°C and a frequency of 10 Hz in a direction perpendicular to the circumferential direction of the fixing member, and E''(2) is the average value of the loss modulus E'' of the surface layer measured at a temperature of 100°C to 150°C and a frequency of 10 Hz in a direction perpendicular to the circumferential direction of the fixing member after removing the perfluoropolyether contained in the pores, and the ratio E''(1) / E''(2) is 0.60 or greater and less than 1.00.

[0007] According to another aspect of the present disclosure, there is provided a method for manufacturing the fixing member, the method including the following steps (i) to (v): Step (i): preparing a laminate having a base layer and a resin layer containing tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA); Step (ii): A step of bringing a first perfluoropolyether heated to a temperature close to the melting point of the PFA into contact with a first surface constituting the outer surface of the resin layer to impregnate the first perfluoropolyether into the resin layer; Step (iii): A step of cooling the laminate obtained in Step (ii), in which the resin layer is impregnated with the first perfluoropolyether, to room temperature; step (iv): removing at least a portion of the first perfluoropolyether impregnated in the resin layer from the first surface side of the resin layer using a fluorine-based solvent to form pores in the resin layer that are open to the first surface of the resin layer; and Step (v): A step of filling at least some of the pores with a mixture containing a second perfluoropolyether and a fluoropolymer-forming mixture, and curing the fluoropolymer-forming mixture.

[0008] According to another aspect of the present disclosure, there is provided a fixing device including the fixing member described above and a heating means for heating the fixing member.

[0009] Furthermore, according to another aspect of the present disclosure, there is provided an electrophotographic image forming apparatus including the above-described fixing device. [Effects of the Invention]

[0010] According to one aspect of the present disclosure, a fixing member capable of achieving both high levels of toner releasability and scratch resistance over a long period of time can be obtained. Also, according to another aspect of the present disclosure, a fixing device and an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images over a long period of time can be obtained. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a cross-sectional schematic view of a fixing belt according to an embodiment of the present disclosure. [Figure 2]1A is a surface observation image of a resin layer of a fixing belt according to Example 1, and FIG. 1B is a cross-sectional image of the resin layer obtained by observing a cross section in the direction along the belt circumferential direction, and FIG. 1C is a cross-sectional image of the surface layer. [Figure 3] FIG. 1 is a schematic perspective view of a fixing belt according to an embodiment of the present disclosure. [Figure 4] FIG. 1 is a cross-sectional view of a fixing device using a fixing belt. [Figure 5] 1 is a schematic cross-sectional view illustrating an electrophotographic image forming apparatus according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] In the present disclosure, unless otherwise specified, the expressions "XX to YY" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints. Furthermore, when a numerical range is described in stages, the upper and lower limits of each numerical range can be combined in any way.

[0013] The present inventors investigated the cause of scratches occurring on the outer surface of the surface layer in areas frequently contacted by the edge of paper during long-term use of the fixing member disclosed in Patent Document 1. Here, in the surface layer of the fixing member disclosed in Patent Document 1, the fluorinated oil exists without phase separation from the fluorinated resin (see paragraph

[0019] of Patent Document 1). When the fluorinated oil and the fluorinated resin are compatible, it is believed that the polymer chains of the fluorinated resin interact with the fluorinated oil, reducing the viscosity of the fluorinated resin in the surface layer. When paper comes into contact with such a surface layer, the portion of the outer surface of the surface layer where the edge of the paper contacts is instantly deformed by the thickness of the paper, resulting in scratches (paper edge scratches) on the outer surface of the surface layer of the fixing member due to burrs on the edge of the paper. The decrease in viscosity of the fluorinated resin constituting the surface layer can be suppressed by reducing the amount of fluorinated oil contained in the surface layer. However, in this case, the fluorinated oil that provides excellent toner release properties to the outer surface of the surface layer is quickly depleted, making it difficult to maintain stable toner release properties over a long period of time. The outer surface of the surface layer is the surface that forms the interface between the surface layer and the atmosphere, and is also the surface that comes into contact with toner or paper.

[0014] Therefore, the present inventors have conducted extensive research to obtain a fixing member that can achieve both long-term toner releasability and high levels of scratch resistance of the surface layer. As a result, the inventors discovered that the above-mentioned objectives can be achieved by a fixing member having an endless belt or roller shape, comprising a base layer and a surface layer, the surface layer having a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA)-containing resin layer (hereinafter also referred to as a "porous PFA layer") and having pores that connect to openings in the outer surface, with perfluoropolyether (PFPE) contained in at least some of the pores, wherein E"(1) is the average value of the loss modulus E" of the surface layer measured at a temperature of 100°C to 150°C and a frequency of 10 Hz in a direction perpendicular to the circumferential direction of the fixing member, and E"(2) is the average value of the loss modulus E" of the surface layer measured at a temperature of 100°C to 150°C and a frequency of 10 Hz in a direction perpendicular to the circumferential direction of the fixing member after removing the PFPE, such that E"(1) / E"(2) is 0.60 or more and less than 1.00.

[0015] First, the surface layer according to the present disclosure has pores that connect to the openings on its outer surface, and at least some of the pores contain PFPE. Therefore, a larger amount of PFPE can be present in the surface layer compared to the surface layer according to Patent Document 1, in which fluorinated oil is contained in a compatible state with the fluorinated resin. As a result, it is believed that the fixing member according to the present disclosure can maintain excellent toner releasability for a long period of time. Next, the loss modulus E" is an index that indicates the magnitude of the viscosity component of a viscoelastic body. If E" in the actual use temperature range (for example, 100°C to 150°C) is small, i.e., if the viscosity is low, the surface layer of the fixing member will instantaneously conform to the shape of the paper edge, making it more likely that scratches due to burrs on the paper edge will occur. On the other hand, if E" in the actual use temperature range is large, i.e., if the viscosity is high, it is thought that the surface layer of the fixing member will be slow to conform to the shape of the paper edge, making it less likely that scratches due to burrs on the paper edge will occur. E"(1) is the average loss modulus of the surface layer when the PFPE is contained in the pores, and E"(2) is the average loss modulus of the surface layer after the PFPE in the pores of the surface layer has been removed. Furthermore, the surface layer according to the present disclosure, which contains a PFPE in its pores, has a loss modulus E"(1) that is 0.60 or more and less than 1.00 times the loss modulus E"(2) of the surface layer after removing the PFPE from the surface layer, despite containing the PFPE. In other words, E"(1) / E"(2) is 0.60 or more and less than 1.00. This means that the surface layer according to the present disclosure, which contains a PFPE in its pores, can maintain a loss modulus close to that of the porous PFA layer, while containing a PFPE. As a result, a fixing member including a surface layer according to the present disclosure can maintain toner releasability over a long period of time and improve the scratch resistance of the outer surface of the surface layer at a high level. The fixing member according to one aspect of the present disclosure will be described in detail below.

[0016] 1. Fixing member The fixing member according to the present disclosure has an endless belt shape or a roller shape. The fixing member has at least a base layer and a surface layer. Fig. 1 is a cross-sectional schematic diagram of a fixing member (hereinafter also referred to as a "fixing belt") 11 having an endless belt shape according to one embodiment of the present disclosure. The fixing belt 11 has a base layer 12 and a surface layer 13 that covers the outer surface of the base layer 12.

[0017] (1) Base layer The material of the base layer 12 is not particularly limited, and any known material used for the base layer of a fixing member can be used, such as metals and alloys such as aluminum, iron, stainless steel, and nickel, and heat-resistant resins such as polyimide. In the fixing belt 11, a substrate having an endless belt shape may be used as the base layer 12. In this case, the material of the base layer 12 may be, for example, nickel, stainless steel, or polyimide, which has excellent heat resistance. The thickness of the base layer 12 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.

[0018] The outer surface of the base layer 12 may be subjected to a surface treatment to impart adhesion to the surface layer 13. Surface treatments can include physical treatments such as blasting, lapping, and polishing, and chemical treatments such as oxidation, coupling agent treatment, and primer treatment, either singly or in combination. Among these treatments, primer treatment is preferred. Examples of primers used in primer treatment include paints prepared by appropriately blending and dispersing a silane coupling agent, silicone polymer, hydrogenated methylsiloxane, alkoxysilane, a reaction-accelerating catalyst, and a colorant such as red iron oxide in an organic solvent. The thickness of the primer layer composed of these primers is not particularly limited, but can be, for example, 1 μm or more and 50 μm or less.

[0019] (2) Surface layer The surface layer 13 contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). As shown in FIG. 2(B), the surface layer 13 has pores 3 that open to a first surface 101 that constitutes the outer surface of the fixing member. The outer surface of the fixing member is defined as the surface that comes into contact with unfixed toner on a recording medium during fixing. The pores 3 preferably do not have a shell. That is, the walls of the pores 3 are preferably formed from a solid portion of the surface layer, specifically, a resin portion 1 containing PFA. At least a portion of the pores 3 contains perfluoropolyether (PFPE).

[0020] Furthermore, the surface layer 13 has an E"(1) / E"(2) ratio of 0.60 or more and less than 1.00, measured at a temperature of 100°C to 150°C and a frequency of 10 Hz in a direction perpendicular to the circumferential direction of the fixing member. Here, the circumferential direction of the fixing member is direction B in the perspective view of the fixing belt 11 shown in FIG. 3, and the direction perpendicular to the circumferential direction is direction A in FIG. 3. One example of a method for controlling E"(1) / E"(2) of the surface layer to 0.60 or more and less than 1.00 is to have PFPE present in a gelled state in the pores 3. This state can be achieved by having a fluoropolymer (hereinafter simply referred to as "fluoropolymer") that has a perfluoroether structure in its molecule, which is common to PFPE, and that has been gelled by forming a three-dimensional crosslinked structure, present in the pores together with PFPE.

[0021] That is, the pores preferably contain a composition containing PFPE and a fluoropolymer. E"(2) means the average value of the loss modulus E" measured at a temperature of 100°C to 150°C and a frequency of 10 Hz in a direction perpendicular to the circumferential direction of the fixing member in a surface layer obtained by removing the PFPE contained in the pores from the surface layer containing PFPE and fluoropolymer in the pores. Here, the pores in the surface layer obtained by removing the PFPE from the pores, for which the value of E"(2) is measured, contain gelled fluoropolymer. Therefore, strictly speaking, E"(2) does not measure the loss modulus of the porous PFA layer. However, the fluoropolymer in the pores is not thought to have a substantial effect on the value of E"(2). That is, although the fluoropolymer in the pores is three-dimensionally crosslinked, it exists within the pores as a gel. When measuring the loss modulus of the surface layer, first the PFA constituting the main skeleton of the surface layer deforms, and then stress is applied to the filler in the pores, causing the filler to deform. At this time, if the filler is more rigid than PFA, it may affect the loss modulus of the surface layer. However, if the filler is a gel, it is not thought to have a substantial effect on the physical properties of the surface layer. Therefore, the loss modulus E"(2) of the surface layer containing PFPE and fluoropolymer in its pores after the PFPE has been removed from the surface layer can be considered to be the same as the loss modulus of the porous PFA layer.

[0022] When the opening ratio of the first surface of the surface layer is P1, P1 is preferably 1.0% or more, more preferably 1.5% or more, and even more preferably 3.0% or more. Furthermore, P1 is preferably 15.0% or less, more preferably 10.0% or less. When P1 is 1.0% or more, the migration of the PFPE in the pores to the first surface of the surface layer is less likely to be hindered, and more stable toner releasability can be imparted to the first surface. Furthermore, when P1 is 15.0% or less, excessive migration of the PFPE in the pores to the first surface can be suppressed, contributing to maintaining stable toner releasability for a longer period of time.

[0023] When the ratio (%) of the area P22 occupied by pores to the area P21 (including the pore portion) of the surface layer in a cross section of the surface layer taken along the circumferential direction of the fixing member (=(P22 / P21) × 100), hereinafter also referred to as "porosity") is P2, P2 is preferably 25.0% or more, more preferably 30.0% or more. The upper limit of P2 is not particularly limited, but is preferably 60.0% or less, more preferably 50.0% or less. Having P2 of 25.0% or more allows the surface layer to retain a larger amount of PFPE. As a result, the first surface can be provided with stable toner release properties over a longer period of time. On the other hand, having P2 of 60.0% or less can better prevent wear due to excessive pores in the surface layer. The porosity can be calculated from a cross section of the surface layer taken along the circumferential direction of the fixing member of the present disclosure, from which the second PFPE contained in the pores in the surface layer has been removed. The porosity can also be calculated from a cross section along the circumferential direction of the fixing member of the PFA resin layer (porous PFA layer) from which the first PFPE has been removed, obtained after the pore formation process in the surface layer formation process described below.

[0024] The average opening diameter of the openings on the first surface of the surface layer is preferably 1 nm or more and 5 μm or less, more preferably 50 nm or more and 1 μm or less. By having an average opening diameter of 1 nm or more, the PFPE present in the pores can be more reliably transferred to the first surface of the surface layer, and excellent toner releasability can be more reliably imparted to the outer surface of the fixing member. On the other hand, by having an average opening diameter of 5 μm or less, it is possible to prevent toner particles adhering to the outer surface of the fixing member from entering the pores, and more reliably prevent the supply of PFPE to the first surface from being hindered.

[0025] The thickness of the surface layer is preferably 10 μm or more and 100 μm or less, and more preferably 15 μm or more and 85 μm or less.

[0026] <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. 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., more preferably 290° C. to 310° C. As 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).

[0027] <Perfluoropolyether (PFPE)> The PFPE contained in at least some 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 surface layer having pores, which will be described later. The second PFPE contained in the pores is not particularly limited, and known ones can be used. As described later, the second PFPE preferably has a structure common to the repeating unit represented by the following structural formula (1) of the fluoropolymer. Specifically, the second PFPE is preferably a PFPE having a structure represented by the following structural formula (2). In addition, the second PFPE is preferably a PFPE that becomes oily at the melting point of the PFA contained in the surface layer.

[0028] [ka]

[0029] In structural formula (2), 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 is a positive integer. The order of the repeating units in structural formula (2) is not limited to the above order. Furthermore, each repeating unit in structural formula (2) may be present in multiple locations in the PFPE. That is, the PFPE having the structure represented by structural formula (2) may be a block copolymer or a random copolymer when it is a copolymer.

[0030] Examples of commercially available second PFPEs include the following: PFPEs having a structure represented by the following structural formula (3) (e.g., Demnum S-200, Demnum S-65 (both trade names), manufactured by Daikin Industries, Ltd.); PFPEs having a structure represented by the following structural formula (4) (e.g., Krytox XHT-1000, Krytox VPF-16256, Krytox GPL-107, Krytox GPL-106, Krytox GPL-105, Krytox GPL-104, Krytox GPL-103, Krytox GPL-104); Krytox GPL-102, Krytox GPL-101 (all trade names), manufactured by Chemours; PFPEs having a structure represented by the following structural formula (5) (e.g., Fomblin M60, Fomblin M100, Fomblin Z25 (all trade names), manufactured by Solvay Specialty Polymers Japan); PFPEs having a structure represented by the following structural formula (6) (e.g., Fomblin Y45, Fomblin Y25 (all trade names), manufactured by Solvay Specialty Polymers Japan).

[0031] [ka]

[0032] (In structural formula (3), n represents a positive integer, and n is a number within the range that ensures that the viscosity of this PFPE at a temperature of 40°C is in the range of 30 mPa·s to 500 mPa·s.)

[0033] [ka]

[0034] (In structural formula (4), n' represents a positive integer, and n' is a number within the range that allows the viscosity of this PFPE at a temperature of 40°C to fall within the range of 10 mPa·s to 2500 mPa·s.)

[0035] [ka]

[0036] (In structural formula (5), m and n'' each independently represent a positive integer, m / n'' is a number that is 0.5 or greater and 2 or less, and m+n'' is a number that provides a viscosity of the PFPE at a temperature of 40°C in the range of 20 mPa s to 1400 mPa s.)

[0037] [ka]

[0038] (In structural formula (6), m' and n''' each independently represent a positive integer, m' / n''' is a number that is 20 or greater and 1000 or less, and m'+n''' is a number that provides a viscosity of the PFPE at a temperature of 40°C in the range of 20 mPa s to 1200 mPa s.)

[0039] The second PFPE more preferably has at least one structure selected from the group consisting of the above structural formulas (3) to (6). Among these, from the viewpoint of compatibility with the fluoropolymer described below, the second PFPE is even more preferably a structure represented by the above structural formula (4).

[0040] The viscosity of the second PFPE contained in the pores at a temperature of 40° C. is preferably 500 mPa·s to 2500 mPa·s, and more preferably 1000 mPa·s to 2000 mPa·s. A PFPE having such a viscosity range contributes to stable migration of the surface layer from the pores to the first surface. The viscosity here is measured using a cone-plate type 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 This is the value measured when the motor is rotated for 60 seconds.

[0041] Examples of commercially available PFPEs that can be used as the second PFPE include "Krytox GPL-105" (viscosity 301 mPa·s), "Krytox GPL-106" (viscosity 459 mPa·s), "Krytox GPL-107" (viscosity 852 mPa·s), "Krytox VPF-16256" (viscosity 1403 mPa·s), and "Krytox XHT-1000" (viscosity 1941 mPa·s) (all trade names, manufactured by Chemours); "Fomblin M60" (viscosity 586 mPa·s), and "Fomblin M100" (viscosity 1327 mPa·s) (all trade names, manufactured by Solvay Specialty Polymers Japan).

[0042] The content ratio of the second PFPE in the surface layer is preferably 5% by mass or more, more preferably 15% by mass or more, based on the total mass of the surface layer, including the mass of the composition containing the second PFPE and the fluoropolymer in the pores.The upper limit of this content ratio is preferably 55% by mass or less, more preferably 30% by mass or less.If the content ratio is 5% by mass or more, the toner releasability can be maintained well for a longer period of time.If the content ratio is 55% by mass or less, the wear of the surface layer due to use can be more reliably prevented. In addition, when a composition containing a second PFPE and a fluoropolymer is contained in the pores of the surface layer, the content ratio of the second PFPE in the surface layer can be calculated from the content ratio of the composition containing the second PFPE and a fluoropolymer in the surface layer described below and the content ratio of the second PFPE in the composition.

[0043] <Fluoropolymer> As described above, one method for controlling the E"(1) / E"(2) ratio of the surface layer to 0.60 or more and less than 1.00 is, for example, to incorporate a fluoropolymer together with a second PFPE into at least a portion of the pores. The present inventors have discovered that by incorporating a PFPE together with a fluoropolymer as a gel-like composition in the pores, the decrease in viscosity of PFA due to the PFPE can be controlled, even if the surface layer contains a PFPE. By incorporating a PFPE together with a fluoropolymer as a gel-like composition in the pores, the PFPE can be prevented from interacting with the polymer chains of the PFA constituting the surface layer, even when a large amount of PFPE is incorporated into the surface layer. Therefore, the decrease in viscosity of PFA due to the PFPE can be suppressed. As a result, the decrease in E"(1) of the surface layer can be suppressed, making it easy to control E"(1) / E"(2) to 0.60 or more and less than 1.00.

[0044] The fluoropolymer according to the present disclosure preferably has a repeating unit represented by the following structural formula (1) and at least one structure of a T unit and a Q unit of siloxane. The structure represented by structural formula (1) is common to the perfluoroalkyl ether structure of PFPE. Therefore, a fluoropolymer having the structure represented by structural formula (1) has a high affinity with PFPE. In addition, the T unit of siloxane is a trifunctional basic unit (RSiO 3 / 2 ), and the Q unit of siloxane is a tetrafunctional basic unit (SiO 4 / 2 ) represents. Examples of the organic substituent R include alkyl groups such as methyl groups; aryl groups such as phenyl groups; alkoxy groups such as methoxy groups; and alkenyl groups such as vinyl groups and allyl groups. Fluoropolymers having at least one of siloxane T units and Q units can stably form a gel due to their three-dimensional polysiloxane structure. Therefore, the fluoropolymer can allow PFPE to exist in the pores as a gel composition due to its high affinity with PFPE due to the structural moiety represented by structural formula (1). The PFPE itself, which exists as a gel composition in the pores, does not have a three-dimensional structure. Therefore, by the step of removing the PFPE from the surface layer for measuring E"(2), which will be described later, the PFPE that exists as a gel composition together with the fluoropolymer in the pores can be removed from the pores.

[0045] [ka]

[0046] In structural formula (1), n ​​represents a positive integer.

[0047] A fluoropolymer having at least one of siloxane T units and Q units and a structure represented by structural formula (1) can be obtained, for example, by using a fluoropolymer-forming mixture containing a compound having a structure represented by structural formula (1) and an unsaturated aliphatic group (-Si-CH2=CH2) bonded to a silicon atom, a crosslinker having a hydrosilyl group (-Si-H), and a catalyst such as platinum, and subjecting the unsaturated aliphatic group and the hydrosilyl group to an addition reaction (hydrosilylation reaction). Alternatively, the fluoropolymer can also be obtained by dehydrating and condensing the alkoxysilyl group of a compound having a structure represented by structural formula (1) and an alkoxysilyl group. In the present disclosure, from the viewpoints of suppressing the generation of by-products and facilitating reaction control, it is preferable to form the fluoropolymer by the hydrosilylation reaction.

[0048] The fluoropolymer-forming mixture that can be used to form the fluoropolymer according to the present disclosure by hydrosilylation reaction will now be described in detail. Examples of the compound contained in the fluoropolymer-forming mixture, which has a structure represented by structural formula (1) and has an unsaturated aliphatic group bonded to a silicon atom, include the compound represented by structural formula (7). The viscosity of this compound is not particularly limited. However, from the viewpoint of ensuring good fluidity of the mixture of the fluoropolymer-forming mixture and the second PFPE when filling the pores in the surface layer with the mixture, it is preferable that the viscosity at a temperature of 23°C is 0.50 Pa·s to 40.0 Pa·s. The viscosity here is measured using a cone-plate type dynamic viscoelasticity measuring apparatus (rheometer) with a cone angle of 1 degree and a cone radius of 20 mm at a measurement temperature of 23°C and a shear rate of 100 s -1 This is the value measured when the motor is rotated for 60 seconds.

[0049] [ka]

[0050] In the structural formula (7), R1 to R4 each independently represent -H, -CH3, or -CH=CH2, L1 and L2 each independently represent an alkylene group having 1 to 4 carbon atoms or -Y-NR5-CO- (wherein Y is an alkylene group having 1 to 4 carbon atoms or an o-, m-, or p-phenylene group represented by the following structural formula (i), and R5 represents -H, -CH3, or -CH5). Furthermore, a and b each independently represent 0 or 1. Rf1 represents a structure represented by the following structural formula (ii):

[0051] [ka]

[0052] [ka]

[0053] In structural formula (ii), m and q each independently represent 0 or an integer of 1 to 150, and m+q is 2 to 200. n and p each independently represent an integer of 1 to 3, o represents 0 or an integer of 1 to 6, and r represents 2 or 3.

[0054] Next, examples of crosslinking agents contained in the fluoropolymer-forming mixture include a fluorine-containing organosilicon compound represented by the following structural formula (8) capable of forming a siloxane T unit structure, and an organosilicon compound represented by the following structural formula (9) capable of forming a siloxane Q unit structure. The fluorine-containing organosilicon compound represented by structural formula (8) is added to the compound represented by structural formula (7) by a hydrosilylation reaction to form a fluoropolymer having a siloxane T unit structure. Furthermore, the organosilicon compound represented by structural formula (9) is added to the compound represented by structural formula (7) by a hydrosilylation reaction to form a fluoropolymer having a siloxane Q unit structure. Furthermore, by having a polysiloxane structure of T units or Q units, the fluoropolymer according to the present disclosure has a three-dimensional crosslinked structure. Therefore, it is thought that by reacting the compound represented by structural formula (7) with the crosslinking agent in the mixture (solution) of liquid PFPE and the fluoropolymer-forming mixture, the liquid PFPE is incorporated into the polysiloxane structure of T units and Q units, resulting in a gel.

[0055] [ka]

[0056] In the structural formula (8), L3 and L4 each independently represent an alkylene group having 1 to 4 carbon atoms, or -Y-NR5-CO- (wherein Y is an alkylene group having 1 to 4 carbon atoms, or an o-, m-, or p-phenylene group represented by the structural formula (i) above, and R5 represents -H, -CH3, or -CH5). Furthermore, c and d each independently represent 0 or 1. Rf2 represents a structure represented by the structural formula (ii) above, or a perfluoroalkylene group having 1 to 20 carbon atoms.

[0057] Furthermore, the catalyst contained in the fluoropolymer-forming mixture may be any known catalyst used in hydrosilylation reactions, including platinum catalysts such as chloroplatinic acid, alcohol-modified chloroplatinic acid, and complexes of chloroplatinic acid and olefins.

[0058] The heating temperature and heating time for curing (hydrosilylation) the fluoropolymer-forming mixture can be selected depending on the desired reaction rate. For example, the heating temperature is preferably in the range of 100°C to 250°C, particularly 150°C to 200°C, and the heating time is preferably in the range of 60 seconds to 4 hours.

[0059] The fluoropolymer-forming mixture may be commercially available. For example, the following is an example of a commercially available fluoropolymer-forming mixture containing a compound having a vinyl group bonded to a silicon atom, represented by the following structural formula (7-1), a crosslinking agent represented by the above structural formula (8), and a platinum catalyst. Liquid fluoroelastomers "SIFEL X-71-359" and "SIFEL 8070A / B" (both product names, manufactured by Shin-Etsu Chemical Co., Ltd.) "SF5000" and "SF7000" (both product names, manufactured by Fujikura Composites)

[0060] [ka]

[0061] The fluoropolymer-forming mixture according to the present disclosure may be commercially available as either a one-component or two-component type. A filler may also be added to the fluoropolymer-forming mixture according to the present disclosure, as long as it can be introduced into the pores of the surface layer together with the second PFPE. Examples of fillers include silica, carbon powder, and metal oxides (e.g., titanium oxide, aluminum oxide, etc.).

[0062] The content ratio of the fluoropolymer in the surface layer is preferably 5% by mass or more and 55% by mass or less, more preferably 15% by mass or more and 30% by mass or less, based on the total mass of the surface layer, including the mass of the composition containing the second PFPE and the fluoropolymer in the pores.If the content ratio is 5% by mass or more, the toner releasability can be maintained well even during longer use.In addition, if the content ratio is 55% by mass or less, the wear of the surface layer due to use can be more reliably prevented.

[0063] The fixing member according to one embodiment of the present disclosure contains a composition of the second PFPE and the fluoropolymer in at least some of the pores in the surface layer. When only PFPE is contained in the pores, the migration of the PFPE in the surface layer to the first surface of the surface layer proceeds relatively quickly. On the other hand, in the fixing member according to one embodiment of the present disclosure, the second PFPE is incorporated into the three-dimensional crosslinked structure of the polysiloxane composed of T units and Q units of the fluoropolymer, and is thought to exist in the pores in a gelled state. Therefore, even when the surface layer of the fixing member is deformed during the fixing process, excessive migration of the PFPE to the first surface of the surface layer is suppressed. As a result, the second PFPE contained in the surface layer is less likely to be depleted early, and can continue to impart stable toner release properties to the first surface of the surface layer for a longer period of time. As mentioned above, the second PFPE in the pores of the surface layer is considered to be held in the network structure formed by the three-dimensional crosslinking of the fluoropolymer, and to exist as a gel composition.In order to stably hold the second PFPE in the three-dimensional crosslinking structure of the fluoropolymer, it is preferable that the second PFPE has the same chemical structure as the fluoropolymer.From this point of view, the second PFPE is particularly preferably the PFPE having the structure represented by the above-mentioned structural formula (4), which has the same structure as the structure represented by the above-mentioned structural formula (1) that the fluoropolymer has.

[0064] The content ratio (mass ratio) of the second PFPE in the composition, i.e., the mass of the second PFPE / (total mass of the second PFPE and the fluoropolymer) is preferably 0.20 or more and 0.80 or less, more preferably 0.40 or more and 0.60 or less.When the content ratio is 0.20 or more, the retention by the fluoropolymer is not excessively strong, and the migration of the PFPE to the first surface is more smoothly carried out.In addition, when the content ratio is 0.80 or less, the crosslinking reaction of the fluoropolymer is not inhibited, and the retention by the fluoropolymer is maintained, and excessive surface migration of the PFPE can be suppressed. The content ratio is calculated as follows. As described below, the content ratio (mass%) of the composition relative to the total mass of the surface layer is calculated by thermogravimetry. Alternatively, the surface layer can be immersed in a fluorine-based solvent to extract only the second PFPE, and the content ratio (mass%) of the second PFPE in the surface layer can be measured. The content ratio of the second PFPE in the composition can then be calculated from the content ratio (mass%) of the second PFPE / the content ratio (mass%) of the composition.

[0065] The content ratio of the composition in the pores to the total mass of the surface layer, including the mass of the composition containing the second PFPE and the fluoropolymer in the pores, is preferably 20% by mass or more and 60% by mass or less, and more preferably 30% by mass or more and 50% by mass or less. If the content ratio of the composition is 20% by mass or more, the migration of the PFPE from the surface layer to the first surface is less likely to be inhibited, and more stable toner releasability can be imparted to the first surface. Furthermore, if the content ratio of the composition is 60% by mass or less, wear of the surface layer can be better prevented.

[0066] <Method of manufacturing the fixing member> A non-limiting example of a method for producing the fixing member according to one embodiment of the present disclosure includes a method including the following steps (i) to (v). Step (i): preparing a laminate having a base layer having an endless belt shape or a roller shape and a resin layer containing PFA on the outer peripheral surface of the base layer; Step (ii): bringing a first PFPE heated to a temperature close to the melting point of PFA into contact with a first surface constituting the outer surface of the resin layer to impregnate the first PFPE into the resin layer; Step (iii): cooling the laminate obtained in step (ii), in which the resin layer is impregnated with the first PFPE, to room temperature; Step (iv): removing at least a portion of the first PFPE impregnated in the resin layer from the first surface side of the resin layer using a fluorine-based solvent to form pores in the resin layer that are open to the first surface of the resin layer; and Step (v): Filling at least some of the pores with a mixture comprising a second PFPE and a fluoropolymer-forming mixture, and curing the fluoropolymer-forming mixture. This results in a fixing member having a surface layer in which the resin layer serves as the surface layer according to the present disclosure and in which at least a portion of the pores contain the second PFPE, preferably a gel composition comprising the second PFPE and a fluoropolymer.

[0067] The present inventors speculate as follows about the mechanism by which the fixing member according to one aspect of the present disclosure is formed by the above method. In step (ii), the first surface of the resin layer is brought into contact with the first PFPE at a temperature near the melting point of the PFA contained in the resin layer (300°C±50°C, preferably 290°C to 325°C), thereby impregnating the first PFPE into the resin layer.

[0068] Next, in step (iii), the resin layer is cooled to room temperature (e.g., 20°C to 35°C, preferably 25°C). Step (iii) may be performed while the resin layer is in contact with the PFPE, for example, in a PFPE bath, or after the resin layer is removed from the PFPE bath. However, if the resin layer is cooled after being removed from the high-temperature PFPE bath, the first surface side of the resin layer may shrink as it cools, and the first PFPE impregnated near the first surface side of the resin layer may be released to the outside. Release of the first PFPE to the outside of the resin layer due to shrinkage of the resin layer is particularly likely when the viscosity of the first PFPE is low. As a result, the area occupied by the first PFPE impregnated in the resin layer decreases, and the volume of voids formed by removing the first PFPE from the resin layer in step (iv), described below, is relatively reduced. Therefore, the resin layer is preferably removed from the first PFPE bath after the temperature of the PFPE bath is cooled to at least the melting point of PFA (specifically, for example, 296° C.) or less, preferably 250° C. or less, and more preferably room temperature. This can prevent the resin layer from shrinking when removed from the PFPE bath, even when a low-viscosity PFPE is used as the first PFPE.

[0069] Next, in step (iv), the first PFPE is removed from the resin layer using a fluorine-based solvent, thereby forming open pores on the first surface of the resin layer at the locations where the first PFPE was present in the resin layer. That is, step (iv) is positioned as a step of forming a porous PFA layer. Note that in step (iv), almost all of the impregnated first PFPE can be eluted from the resin layer. By increasing the amount of the first PFPE impregnated into the resin layer, the number of pores formed inside the resin layer can be increased.

[0070] In step (ii), the first PFPE is impregnated so that the content ratio of the first PFPE relative to the total mass of the resin layer impregnated with the first PFPE is preferably 25% by mass or more and 60% by mass or less, more preferably 30% by mass or more and 55% by mass or less. If the content ratio of the first PFPE is 25% by mass or more, the PFPEs are likely to aggregate, facilitating the formation of pores. Furthermore, if the content ratio of the first PFPE is 60% by mass or less, the decrease in mechanical strength due to the increase in porosity can be suppressed. Here, the content ratio of the first PFPE is defined as the ratio (mass %) of the mass of the first PFPE impregnated in the resin layer to the sum of the mass of the resin layer itself before impregnation with the first PFPE and the mass of the first PFPE impregnated in the resin layer. Specifically, when the total mass of the resin layer impregnated with the first PFPE is X and the total mass of the resin layer before impregnation with the first PFPE is Y, the content ratio (impregnation ratio) Z of the first PFPE to the total mass of the resin layer is calculated by the following formula: Z(mass%)={(XY) / X}×100. The content ratio of the first PFPE can be calculated using a thermogravimetric analyzer as described in the Examples.

[0071] The amount of the first PFPE impregnated into the resin layer 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, the higher the temperature within the temperature range (250°C to 350°C) near the melting point of PFA, the lower the viscosity of the first PFPE, and the longer the contact time with the resin layer, the more the amount of the first PFPE impregnated into the resin layer can be increased. As described above, in order to avoid shrinkage of the resin layer in step (iii), it is preferable to perform step (iii) in a PFPE bath.

[0072] The viscosity of the first PFPE at a temperature of 40°C is preferably 10 mPa·s to 400 mPa·s, and more preferably 30 mPa·s to 350 mPa·s. Commercially available PFPEs with 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) (all trade names, manufactured by Chemours).

[0073] For example, when the viscosity (40°C, same below) of the first PFPE is 301 mPa·s, the thickness of the resin layer containing PFA is 20 μm, the melting point of the resin layer is 296°C, and the temperature at the time of contact between the resin layer and the first PFPE is 310°C, a PFPE-impregnated resin layer having a first PFPE content of 30 mass% can be produced with a contact time of 1 minute. Furthermore, when a PFPE having a viscosity of 111 mPa·s is used as the first PFPE and the other conditions are the same as above, a PFPE-impregnated resin layer having a first PFPE content of 41 mass% can be produced.Furthermore, when a PFPE having a viscosity of 111 mPa·s is used as the first PFPE, the temperature at the time of contact with the resin layer is 300°C, and the other conditions are the same as above, a PFPE-impregnated resin layer having a first PFPE content of 26 mass% can be produced. Furthermore, using a PFPE with a viscosity of 54 mPa·s as the first PFPE, and assuming the other conditions are the same as above, a PFPE-impregnated resin layer with a first PFPE content of 33% by mass can be produced. Furthermore, a resin layer using the above-mentioned PFPE with a viscosity of 54 mPa·s is immersed in a bath of the first PFPE at a temperature of 310°C, and the resin layer and the first PFPE are brought into contact for 1 minute. The temperature of the PFPE bath is then cooled to 250°C, and the resin layer is then removed from the PFPE bath, thereby obtaining a PFPE-impregnated resin layer with a first PFPE content of 58% by mass. Furthermore, if the resin layer is removed from the PFPE bath after the temperature of the PFPE bath has been cooled to 25°C, a PFPE-impregnated resin layer with a first PFPE content of 60% by mass can be obtained, assuming the other conditions are the same as above. As described above, when the resin layer is removed from the PFPE bath after cooling the temperature of the PFPE bath to 25°C, the content of the first PFPE in the resin layer is 2% by mass higher than when the resin layer is removed from the PFPE bath after cooling the temperature of the PFPE bath to 250°C. This is thought to be because volatilization of the first PFPE from the resin layer is suppressed when the resin layer is removed from the PFPE bath after cooling the temperature of the PFPE bath to 25°C. As long as the resin layer does not shrink, volatilization of the first PFPE after removing the resin layer from the PFPE bath does not affect the volume of pores in the resin layer formed through step (iv).

[0074] On the other hand, the PFPE used in the examples of Patent Document 1 (trade name: Krytox GPL-106, manufactured by Chemours) has a viscosity of 459 mPa·s. When such PFPE was brought into contact with a resin layer containing PFA at a temperature of 345°C for 5 minutes, a PFPE-impregnated resin layer with a PFPE content of 24 mass% was obtained. However, with a PFPE content of this level, the PFPEs did not aggregate within the resin layer. Therefore, even when the PFPE was subsequently eluted using a fluorine-based solvent, no pores were formed in the resin layer.

[0075] In the preparation of a fixing member, any method can be used to contact the resin layer with the first PFPE, as long as the first PFPE can be brought into contact with the resin layer at a temperature near the melting point of the PFA contained in the resin layer. The resin layer to be contacted with the first PFPE may be a resin layer in a laminate in which a base layer and a resin layer are previously laminated, or a PFA sheet or PFA tube for the resin layer may be prepared, with the surface to be bonded to the base layer masked. Examples of contact methods include dipping. A particularly preferred method involves inserting a tubular PFA into a base layer treated with a primer (e.g., addition-curing silicone rubber), removing excess primer, curing the resulting laminate, and then immersing the laminate in an impregnation device containing a heated first PFPE. The tubular PFA can be produced as a tube of desired thickness, diameter, and length by known methods, such as extrusion molding, transfer molding, blow molding, etc. The tubular PFA has no seams and a relatively uniform thickness, making it easy to form a resin layer with excellent uniformity in thickness in the shape of an endless belt.

[0076] In step (iv), the fluorine-based solvent used to remove the first PFPE impregnated into the resin layer is a solvent capable of dissolving the first PFPE but not dissolving PFA. The resin layer is then immersed in the fluorine-based solvent so that the first surface is immersed. Here, the "solvent capable of dissolving the first PFPE" refers to, for example, a solvent that dissolves 10 g or more of the first PFPE per 100 g of solvent at 25° C. On the other hand, the "solvent that does not dissolve PFA" refers to, for example, a solvent that dissolves 1 g or less of PFA per 100 g of solvent at 25° C. Examples of fluorine-based solvents that can dissolve the first PFPE but do not dissolve PFA include hydrofluoroether (trade name: Novec 7300, manufactured by 3M). Furthermore, in step (iv), when removing the first PFPE from the resin layer, applying ultrasonic waves to the resin layer is preferred to promote removal of the first PFPE from the resin layer.

[0077] The method for manufacturing the fixing member according to one embodiment of the present disclosure will be described more specifically. Step (i): A laminate in which a base layer and a resin layer containing PFA are laminated in this order is attached to a dipping device. Step (ii): The laminate is immersed in a bath of a first PFPE heated to near the melting point of PFA (300°C±50°C, preferably 290°C to 325°C) and left standing for preferably 20 seconds to 5 minutes, more preferably 30 seconds to 2 minutes (e.g., 1 minute) (impregnation step-1). It was found that in the impregnation step-1, the higher the contact temperature between the resin layer and the first PFPE and the lower the viscosity of the first PFPE, the greater the amount of impregnation of the first PFPE. The contact temperature and the viscosity of the first PFPE can be appropriately selected as long as an impregnation amount of the first PFPE equal to or greater than a certain amount sufficient to form the specific pores is achieved. In the impregnation step-1, when the heating temperature of the first PFPE is A°C and the melting point of PFA is B°C, AB (°C) is preferably 0°C to 40°C, more preferably 3°C to 20°C. Step (iii): The laminate is removed from the first PFPE bath and cooled to room temperature. As described above, step (iii) is preferably performed in a PFPE bath to avoid a decrease in the amount of PFPE in the resin layer due to volatilization of the first PFPE and shrinkage of the resin layer. Step (iv): After cooling, the laminate is immersed in a fluorine-based solvent that can dissolve the first PFPE but not PFA, and the first PFPE impregnated in the resin layer is eluted from the openings on the first surface of the resin layer (pore-forming step).By this step, pores that open on the first surface are formed in the resin layer.That is, a porous PFA layer is formed.

[0078] Step (v-1): The laminate having a resin layer (porous PFA layer) having voids obtained through the above step is immersed in a mixture of the second PFPE and a fluoropolymer-forming mixture for preferably 5 to 30 minutes, more preferably 10 to 30 minutes (e.g., 15 minutes). This allows the voids in the resin layer to be impregnated with the mixture containing the second PFPE and the fluoropolymer-forming mixture (hereinafter, the "mixture containing the second PFPE and the fluoropolymer-forming mixture" may be referred to as "mixture A") (impregnation step-2). The temperature of the mixture A at this time is preferably a temperature at which the curing of the fluoropolymer-forming mixture in the mixture A during impregnation does not proceed easily. As a non-limiting example, the temperature of the mixture A in this step is preferably 0°C or higher and preferably 100°C or lower. The temperature of the mixture A is more preferably 50°C or lower.

[0079] The mixture A of the second PFPE and the fluoropolymer-forming mixture has fluidity, so it can be easily introduced into the pores of the resin layer (porous PFA layer). In the present disclosure, PFA, which has high chemical affinity with the fluoropolymer and PFPE, is used as the resin, so that the mixture A can be easily introduced throughout the entire thickness of the PFA.

[0080] The solubility parameter difference (ΔHSP) between the mixture A containing the second PFPE and the fluoropolymer-forming mixture and the PFA constituting the surface layer is 10.0 (MPa) 0.5 Preferably, it is 7.0 (MPa) or less. 0.5 It is more preferable that the difference in solubility parameters is 10.0 (MPa) or less. 0.5 If the ratio is equal to or less than this, the mixture A can be introduced into the pores more smoothly. The solubility parameter (SP value) is a parameter expressed as the square root of molecular cohesive energy and serves as a measure of the affinity between two or more substances. In this disclosure, the SP value is derived using the Hansen method. Here, the Hansen method expresses the energy of a substance using three components: dispersion energy term (δD), polarization energy term (δP), and hydrogen bond energy term (δH), and represents them as vectors in three-dimensional space. For example, if the difference in SP values ​​(ΔHSP) between two substances is small (the distance between the two substances is short), the two substances are highly soluble, i.e., easily miscible. On the other hand, if the difference in SP values ​​between two substances is large (the distance between the two substances is long), the two substances are less soluble, i.e., less miscible. δD, δP, and δH can be calculated using the 3rd Edition 3.1.14 of the database-equipped calculation software "HSPiP (product name)" developed and sold by the Hansen Group. At this time, the SP value of each component is calculated based on the following formula (a). SP value = (δD 2 +δP 2 +δH 2 ) 0.5 (a) The difference in solubility parameters (ΔHSP) between two components is defined as the distance in the three-dimensional space, and is calculated based on the following formula (b): where δD1 and δD2 represent the dispersion energy terms of each component, δP1 and δP2 represent the polarization energy terms of each component, and δH1 and δH2 represent the hydrogen bond energy terms of each component. ΔHSP={4(δD1-δD2) 2 +(δP1-δP2) 2 +(δH1-δH2) 2 } 0.5 (b)

[0081] Here, when the mixture for forming a fluoropolymer contains a compound having the structure represented by the above structural formula (7), the substantial structural difference between the compound and the second PFPE is only that unsaturated aliphatic groups are bonded to both ends of the compound. Therefore, the SP values obtained by the above method for the compound and the second PFPE are almost the same. Also, in the mixture for forming a fluoropolymer, since the compound is the main component, as the SP value of the mixture A containing the mixture for forming a fluoropolymer and the second PFPE, the SP value of the compound or the SP value of the second PFPE can be used.

[0082] Step (v-2): Take out the laminate obtained through the above step (v-1) from the mixture A, and remove the mixture A adhering to the outer surface. Next, cure the mixture for forming a fluoropolymer in the mixture A introduced into the pores to obtain a fluoropolymer. Thereby, a fixing member according to one aspect of the present disclosure containing a composition containing the second PFPE and the fluoropolymer in at least a part of the pores is obtained. In this step, the method for removing the excess amount of the mixture A adhering to the outer surface is not particularly limited, and examples thereof include washing with a fluorine-based solvent, removing with air, wiping with a non-woven fabric, and the like. Examples of the method of washing with a fluorine-based solvent include a method of removing using fibers such as a non-woven fabric impregnated with a fluorine-based solvent. Examples of the fluorine-based solvent include hydrofluoroether (trade name: Novec7300, manufactured by 3M Company), etc. The heating temperature and heating time in the curing can be selected so as to make the reaction rate of the reaction components in the mixture for forming a fluoropolymer into a desired state. The heating temperature is preferably in the range of 100°C to 250°C, and more preferably in the range of 150°C to 200°C. The heating time is preferably in the range of 60 seconds to 4 hours.

[0083] <Measurement methods of E”(1) and E”(2)> An example of the measurement method of E”(1) and E”(2) of the surface layer of the fixing member according to one aspect of the present disclosure obtained as described above will be described.

[0084] Measurement of E”(1) First, only the surface layer is taken out from the fixing member. For example, when the fixing member has an endless base layer and a surface layer made of a fluororesin tube fixed via a primer layer composed of a cured product of an addition-curing type silicone rubber adhesive on the outer peripheral surface thereof, the interface between the base layer and the primer layer is peeled off using a knife or the like to obtain a laminated sample (1) of the primer layer and the surface layer. This laminated sample (1) is immersed in a dissolving agent for silicone resin, for example, “e-solve 21RS” (trade name, manufactured by Kaneko Chemical Co., Ltd.) to dissolve the silicone rubber in the primer layer. Thereby, the primer layer is removed from the laminated sample (1) to obtain a sample composed only of the surface layer. From this sample, a measurement sample is cut out so that the length in the circumferential direction of the fixing member is 5 mm and the length in the direction orthogonal to the circumferential direction of the fixing member is 20 mm. For this measurement sample, E”(1) is measured by the following method using a dynamic viscoelasticity measuring device, for example, “Rheogel E4000” (trade name, manufactured by UBM Co., Ltd.). That is, the measurement sample prepared above is attached to a tensile jig. When attaching, the measurement sample is attached so that the measurement direction, that is, the direction between the chucks of the tensile jig, is orthogonal to the circumferential direction of the fixing member. The distance between the chucks is set to 10 mm, and a sine wave with an applied frequency of 10 Hz and an amplitude of 0.03 mm is used to raise the temperature under the conditions of a measurement temperature of 50°C to 250°C and a heating rate of 5.0°C / min to obtain a measurement temperature - loss elastic modulus E” profile. Among the E” thus obtained, the E” value at 100°C to 150°C is extracted, and the average value thereof is taken as E”(1).

[0085] Measurement of E”(2) A laminated sample (2-1) consisting of a base layer, a primer layer, and a surface layer is obtained from the fixing member. Next, the PFPE present in the pores of the surface layer is removed. While the method is not particularly limited, for example, when the PFPE is present in the pores as a gel-like composition together with a fluoropolymer, the PFPE can be more reliably removed by the following method. Specifically, the laminated sample (2-1) is immersed in a container containing a fluorine-based solvent, such as "Novec 7300" (trade name, manufactured by 3M), so that the surface of the surface layer opposite the side facing the primer layer is completely immersed. The temperature of the fluorine-based solvent is preferably, for example, 20°C to 60°C. Next, the container is placed in a water bath of an ultrasonic wave applying device, such as "Bransonic (Model 2510J-DTH)" (trade name, manufactured by Emerson Japan), and ultrasonic waves are applied. The duration of ultrasonic wave application is not particularly limited as long as the PFPE can be removed from the pores, but is preferably, for example, 60 to 150 minutes. The laminated sample (2-1) is then removed from the container. This process removes the PFPE from the surface layer. Even if the PFPE is present in the pores as a gel-like composition with the fluoropolymer, the PFPE itself is not crosslinked. Therefore, the PFPE in the pores can be removed by immersing the sample in a fluorine-based solvent at an appropriately adjusted temperature and applying ultrasound. Next, the interface between the base layer and the primer layer of the laminate sample (2-1) is peeled off using a knife or the like to obtain a laminate sample (2-2) consisting of the primer layer and the surface layer. Next, the laminate sample (2-2) from which the PFPE in the surface layer has been removed is immersed in a silicone resin solvent, such as "e-Solv 21RS" (trade name, manufactured by Kaneko Chemical Co., Ltd.), to dissolve the silicone rubber in the primer layer. This removes the primer layer from the laminate sample (2-2), obtaining a sample consisting only of the surface layer. A measurement sample is cut from this sample so that it is 5 mm long in the circumferential direction of the fixing member and 20 mm long in the direction perpendicular to the circumferential direction of the fixing member. E"(2) of this measurement sample is measured using a dynamic viscoelasticity measuring device, such as "Rheogel E4000" (trade name, manufactured by UBM), according to the following method. Specifically, the measurement sample prepared above is attached to a tension jig. When attaching, the measurement sample is attached so that the measurement direction, i.e., the direction between the chucks of the tension jig, is perpendicular to the circumferential direction of the fixing member. The chuck distance is set to 10 mm, and a sine wave with an applied frequency of 10 Hz and an amplitude of 0.03 mm is used to raise the temperature at a measurement temperature of 50°C to 250°C and a heating rate of 5.0°C / min, thereby obtaining a measurement temperature-loss modulus E" profile. From the E" thus obtained, the E" values ​​between 100°C and 150°C are extracted, and their average is designated as E"(2).

[0086] 2. Fixing device The fixing device includes a fixing member and a heating means for heating the fixing member. The fixing device may include, for example, a heating rotor and a pressure rotor arranged 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 arranged opposite the heating roller, and a heating film and an elastic pressure roller arranged in contact with the heating film. Other examples of combinations of a heating rotor and a pressure rotor include a heating belt and an elastic pressure roller arranged in contact with the heating belt, and a heating belt and an elastic pressure belt arranged in contact with the heating belt.

[0087] FIG. 4 is a cross-sectional view of a fixing device including a fixing belt 11 for heating and an elastic pressure roller 17, taken along the circumferential direction of the fixing belt. The fixing belt 11 is a fixing belt according to one embodiment of the present disclosure. The fixing belt 11 is loosely fitted around a belt guide member 14. A pressure rigid stay 16 is inserted inside the belt guide member 14. The belt guide member 14 is formed of, for example, a resin having heat resistance and heat insulation properties. The heating means is, for example, a heater arranged in contact with the inner circumferential surface of the fixing belt. A ceramic heater 15 is provided as a heat source at the position where the belt guide member 14 and the inner surface of the fixing belt 11 come into contact. The ceramic heater 15 is fitted into and fixed in a groove provided along the longitudinal direction of the belt guide member 14. The ceramic heater 15 generates heat when electricity is applied by means not shown. The elastic pressure roller 17 has an elastic layer 17b made of hardened silicone rubber provided on the circumferential surface of a stainless steel core 17a. A surface layer 17c made of fluororesin is provided on the circumferential surface of the elastic layer 17b. The thickness of the surface layer 17c is, for example, 50 μm. Pressure springs (not shown) are respectively compressed between both ends of the pressure rigid stay 16 and spring bearing members (not shown) on the device chassis side, thereby applying a downward force to the pressure rigid stay 16. As a result, the lower surface of the ceramic heater 15 disposed on the lower surface of the belt guide member 14 and the upper surface of the elastic pressure roller 17 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 15 is disposed in contact with the inner circumferential surface of the fixing belt 11. A recording medium P, which is a heated object and has an image formed thereon 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 is fused and mixed, and then cooled, thereby being fixed onto the recording medium P.

[0088] 3. Electrophotographic image forming apparatus The electrophotographic image forming apparatus may have a known configuration. For example, there are multifunction machines, copiers, fax machines, printers, etc. that use electrophotography. Here, the overall configuration of an electrophotographic image forming apparatus will be outlined using a color laser printer as an example. Figure 5 is a schematic cross-sectional view of a laser printer 40 according to one embodiment of the present disclosure. The laser printer 40 shown in Figure 5 has an image forming unit equipped with electrophotographic photosensitive drums (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 laser printer 40 also has an intermediate transfer member 38 that holds the color images developed and multi-transferred in the image forming unit and further transfers them to a recording medium P fed from a feeding unit. 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 section 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.

[0089] 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 feed cassette 29 storing a plurality of recording media P, a feed roller 30, a separation pad 31, and a pair of registration rollers 32. During image formation, the feed roller 30 is driven to rotate in accordance with the image formation operation, separating the recording media P in the feed cassette 29 one by one, and conveying them to the secondary transfer portion T2 by the pair of registration rollers 32 in synchronization with the image formation operation. A movable secondary transfer roller 33 is disposed in the secondary transfer section 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 transported at a predetermined transport speed V in the direction indicated by the left arrow in FIG. 5 and is then transported by a transport belt 34 to the fixing section 35, which is the next process. Heat and pressure are applied in the fixing section 35, and the transferred toner image is fixed to the recording medium P. The recording medium P is then discharged by a pair of discharge rollers 36 onto a discharge tray 37 on the top surface of the device. Furthermore, by applying the fixing device illustrated in Figure 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. [Example]

[0090] The present disclosure will be specifically described below using examples. However, the present disclosure is not limited to the following examples. In these examples, fixing members were prepared using the following PFA, perfluoropolyether, and fluoropolymer-forming mixture.

[0091] (PFA) PFA-1: "959HP-Plus" (product name, manufactured by Mitsui Chemours Fluoroproducts, melting point = 296°C) (perfluoropolyether) PFPE-1: "Krytox GPL-104" (trade name, manufactured by Chemours, viscosity: 111 mPa·s (40°C)) PFPE-2: "Krytox VPF-16256" (product name, manufactured by Chemours, viscosity: 1403 mPa s (40℃)) PFPE-3: "Krytox GPL-103" (trade name, manufactured by Chemours, viscosity: 54 mPa·s (40°C)) (Fluoropolymer forming mixture) FP-1: "SIFEL X-71-359" (product name, manufactured by Shin-Etsu Chemical Co., Ltd., viscosity: 8600 mPa·s (23°C))

[0092] [Example 1] <Production of fixing belt> [Preparation of a laminate having a base layer and a resin layer containing PFA] A nickel electroformed endless belt-shaped substrate with an inner diameter of 30 mm, a width of 400 mm, and a thickness of 40 μm was prepared as the base layer. An addition-curing silicone rubber adhesive (product name: SE1819CV, a mixture of equal parts of "liquid A" and "liquid B" manufactured by Dow Corning Toray Co., Ltd.) was applied to the outer surface of this substrate as a primer, with a thickness of approximately 20 μm. Hereinafter, the layer of primer applied to the base layer will be referred to as the "primer layer." Next, the base layer on which the primer layer was formed was covered with a fluororesin tube (PFA-1, melting point 296°C, thickness 20 μm) whose inner surface had been hydrophilically treated, and the belt surface was uniformly rubbed from above the fluororesin tube. This caused excess adhesive to be squeezed out from between the base layer and the fluororesin tube. The base layer covered with the fluororesin tube was then placed in an electric furnace set at a temperature of 200°C and heated for 1 hour to cure the addition-curing silicone rubber and bond the fluororesin tube (resin layer) to the base layer. Both ends were then cut to obtain a laminate for a fixing belt with a width of 343 mm.

[0093] [PFPE contact impregnation] (Impregnation process-1) The first PFPE (PFPE-1) was placed in a borosilicate glass measuring cylinder. The measuring cylinder was entirely wrapped with a heating wire covered with a heat insulating material and heated to 310° C. The prepared laminate was attached to a dipping device and immersed in the heated first PFPE for 1 minute, and then the laminate was removed.

[0094] <Evaluation A-1: ​​Measurement of the content ratio of the first PFPE in the resin layer impregnated with the first PFPE> The content ratio of the first PFPE in the obtained resin layer impregnated with the first PFPE was measured by the following method. That is, a laminated sample of a primer layer and a resin layer was cut out from the laminate. Then, the laminated sample was immersed in a silicone resin solvent (trade name: e-solv 21RS, manufactured by Kaneko Chemical Co., Ltd.) to dissolve the silicone rubber in the primer layer, thereby removing the primer layer from the laminated sample. In this way, a measurement sample consisting only of the entire thickness of the resin layer was prepared. This measurement sample was measured using a thermogravimetric analyzer (TGA) under the following conditions, and the content ratio (mass%) of the first PFPE in 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 above-mentioned thermogravimetric analysis, obtain linear least squares approximation formula from the region where the slope is constant and only PFA decreases.Then, the intercept of this linear least squares approximation formula is PFA content (mass%), and calculate first PFPE content (mass%) = 100 - PFA content.

[0095] (Vacancy formation process) After cooling the laminate obtained in the impregnation step-1 to room temperature, the laminate was immersed for 10 minutes in a measuring cylinder containing a separately prepared fluorine-based solvent (trade name: Novec 7300, manufactured by 3M). The measuring cylinder was then placed in a water bath of an ultrasonic cleaning device (trade name: Bransonic (model 2510J-DTH), manufactured by Emerson Japan), and ultrasonic waves were applied for 60 minutes. After treatment, the laminate was removed from the measuring cylinder and left in an environment at 25°C for 60 minutes to dry. Thus, a laminate was obtained from which the first PFPE present on the surface and inside of the resin layer had been removed. The obtained laminate had a white appearance when visually inspected, confirming the formation of pores in the resin layer. 2(A) and 2(B) are schematic diagrams of images of the first surface of the resin layer of the obtained laminate and the cross section of the laminate in the circumferential direction observed with a scanning electron microscope. FIG. 2(A) is a schematic diagram of an SEM image of the first surface. A resin portion 1 containing PFA and openings 2 were observed on the first surface 101 of the obtained laminate. FIG. 2(B) is a schematic diagram of an SEM image of a cross section of the resin layer in the circumferential direction of the laminate. A resin portion 1 containing PFA and pores 3 were observed on the obtained laminate. It was also observed that the pores 3 had openings 2 that connected to the first surface 101. In other words, it was confirmed that a porous PFA layer was formed on the base layer.

[0096] <Evaluation A-2: Calculation of Opening Ratio P1, Average Opening Diameter, and Porosity P2 on the First Surface of the Surface Layer (Resin Layer)> The opening ratio P1 and the average opening diameter on the first surface of the surface layer (resin layer) were calculated as follows. The surface of the laminate obtained in the hole-forming step from which the first PFPE had been removed, i.e., the surface of the resin layer opposite the base layer, was observed using a scanning electron microscope, and an SEM image (magnification 10,000x) of a rectangular 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 the openings could be recognized. The obtained SEM image was converted to an 8-bit grayscale image using image processing software (trade name: Image-J, manufactured by the National Institutes of Health (NIH)). After applying a median filter to the obtained grayscale image, it was further subjected to binarization processing using the image processing software to obtain a binary image. The binarization processing used the YEN method to distinguish between the portions corresponding to the openings and the portions corresponding to the PFA in the SEM image. Then, the ratio of the number of pixels corresponding to the openings in the obtained binary image to the number of pixels in the entire image was calculated. The observation areas were set at 10 arbitrary positions on the surface of the resin layer having openings, and the arithmetic mean value of the ratio calculated from each observation area was defined as the aperture ratio P1. Note that the observation areas were set at positions that 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).

[0097] The porosity P2 was calculated as follows. A cross-sectional sample was cut from the resin layer of the laminate from which the first PFPE had been removed using a cryo-ultramicrotome (manufactured by Leica Microsystems) to reveal a cross-section of the resin layer in the circumferential direction of the laminate. The cross-section included the entire thickness of the resin layer. The cross-section was then observed using a scanning electron microscope, and an SEM image of a rectangular 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 (trade name: MATLAB (registered trademark), manufactured by MathWorks) to obtain a binarized image. The binarization process used Otsu's method to distinguish between the portions corresponding to voids and the portions corresponding to PFA in the SEM image. The ratio of the number of pixels in the portion corresponding to voids in the binarized image to the number of pixels in the entire image was then calculated. The SEM images were taken at three positions in the thickness direction of the cross section of the cross section 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 surface on one side of the resin layer (hereinafter also referred to as the "first surface") to the surface on the other side (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 and second surfaces of the resin layer 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 resin layer toward the first surface, and the long side of the observation area is parallel to the second surface.

[0098] 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.

[0099] (Impregnation process-2) Next, the laminate having a resin layer with voids obtained through the above-mentioned void formation step was subjected to the following operation. That is, a mixture A of a second PFPE (PFPE-2) and a fluoropolymer-forming mixture (FP-1) was prepared. The content ratio (mass ratio) of the second PFPE relative to the mass of mixture A was set to 0.19. The mixture A was placed in a borosilicate glass measuring cylinder. The second PFPE and the fluoropolymer-forming mixture (FP-1) were compatible, and the mixture A was a transparent liquid. The laminate with voids formed in the resin layer was attached to a dipping device, and the entire laminate was immersed in the mixture A for 30 minutes and then removed. The immersion was carried out at room temperature (25°C). Next, a nonwoven fabric impregnated with a fluorine-based solvent (product name: Novec 7300, manufactured by 3M) was used to remove the mixture A adhering to the outer surface of the laminate removed from the mixture A. The laminate was then placed in an oven and heated at 200°C for 1 hour to cure the fluoropolymer-forming mixture. This resulted in a fixing belt No. 1 according to this example, which had a surface layer containing a composition containing PFPE-2 and a fluoropolymer (a cured product of FP-1) in the pores. Figure 2(C) shows a schematic image of a cross section of the surface layer of the fixing belt taken along the circumferential direction, observed with a scanning electron microscope. It was confirmed that the pores 3 observed in Figure 2(B) had been filled with a composition 4 containing a second PFPE and a fluoropolymer in the impregnation step 2.

[0100] <Evaluation A-3: Content ratio of the composition containing the second PFPE and the fluoropolymer in the surface layer> The obtained fixing belt containing the composition containing the second PFPE and the fluoropolymer was subjected to the same method as described above to obtain a measurement sample consisting of only the entire thickness of the surface layer. This measurement sample was measured using a thermogravimetric analyzer (TGA) under the following conditions, and the content ratio (mass%) of the composition to the total mass of the surface layer, including the mass of the composition containing the second PFPE and the fluoropolymer in the pores, was calculated. Apparatus: TGA851 (trade name, manufactured by METTLER TOLEDO) Atmosphere: In air Temperature: 425℃ In the profile of the measurement time-weight loss rate obtained by the thermogravimetric analysis, a linear least squares approximation formula was obtained from the region where the slope was constant and only PFA was decreasing.Then, the intercept of the linear least squares approximation formula was taken as the PFA content (mass%), and the content (mass%) of the composition containing the second PFPE and the fluoropolymer was calculated as 100-PFA content.

[0101] <Evaluation A-4: Content ratio of second PFPE in composition containing second PFPE and fluoropolymer> A measurement sample consisting of only the entire thickness of the surface layer was obtained from a fixing belt having a surface layer whose pores were filled with a composition containing a second PFPE and a fluoropolymer, using the same method as described above. First, the mass C of the measurement sample was measured. Next, the measurement sample was immersed completely in a beaker containing a separately prepared fluorine-based solvent (trade name: Novec 7300, manufactured by 3M). Next, the beaker was placed in a water bath of an ultrasonic cleaning device (trade name: Bransonic (model 2510J-DTH), manufactured by Emerson Japan) and ultrasonic waves were applied for 120 minutes to elute the second PFPE in the pores. It was confirmed that the fluoropolymer in the pores was not eluted by this operation. Next, the measurement sample was removed from the beaker and left in an environment at 25°C for 60 minutes to dry. The mass D of the measurement sample after drying was measured, and the content ratio (mass%) of the second PFPE in the surface layer was calculated using {(CD) / C} x 100. The content ratio of the second PFPE in the composition comprising the second PFPE and the fluoropolymer (content ratio of the second PFPE (mass%) / content ratio of the composition comprising the second PFPE and the fluoropolymer (mass%)) was calculated from the content ratio of the second PFPE in the obtained surface layer and the content ratio of the composition comprising the second PFPE and the fluoropolymer in the surface layer calculated by the above-mentioned method.

[0102] <Evaluation A-5: E”(1) / E”(2) measurement> The loss modulus E" (1) of the surface layer was measured by the following method. A laminate sample (1) consisting of a primer layer and a resin layer (surface layer) was cut out from the laminate. Next, the laminate sample (1) was immersed in a silicone resin solvent (trade name: eSolv 21RS, manufactured by Kaneko Chemical Co., Ltd.) to dissolve the silicone rubber in the primer layer. In this way, the primer layer was removed from the laminate sample, and a sample consisting only of the entire thickness of the resin layer was prepared. This sample was cut out to a length of 5 mm in the circumferential direction of the fixing member and a length of 20 mm in the direction perpendicular to the circumferential direction of the fixing member, and used as a measurement sample. E"(1) of this measurement sample was measured under the following conditions using a dynamic viscoelasticity measuring device (product name: Rheogel E4000, manufactured by UBM). First, the measurement sample was attached to the tension jig. When attaching, the measurement sample was attached so that the measurement direction, i.e., the direction between the chucks of the tension jig, was perpendicular to the circumferential direction of the fixing member. The distance between the chucks was set to 10 mm, and a sine wave with an applied frequency of 10 Hz and an amplitude of 0.03 mm was used to raise the temperature at a measurement temperature of 50°C to 250°C and a heating rate of 5.0°C / min, thereby obtaining a measurement temperature-loss modulus E" profile. From the obtained E" values, the E" values ​​between 100°C and 150°C were extracted, and their average value was defined as E"(1).

[0103] The loss modulus E" (2) of the surface layer was measured by the following method. A laminate sample (2-1) consisting of a base layer, a primer layer, and a resin layer (surface layer) was cut out from the laminate. Next, in order to remove PFPE, the laminate sample (2-1) was immersed completely in a beaker containing a separately prepared fluorine-based solvent (trade name: Novec 7300, manufactured by 3M). The temperature of the fluorine-based solvent was adjusted to 25°C. Next, the beaker was placed in a water bath of an ultrasonic cleaning device (trade name: Bransonic (model 2510J-DTH), manufactured by Emerson Japan), and ultrasonic waves were applied for 120 minutes to remove PFPE from the laminate sample (2-1). The temperature of the fluorine-based solvent was maintained at 25°C to 60°C during the ultrasonic application. After the ultrasonic application treatment, the laminate sample (2-1) was removed from the beaker and left to dry in an environment at 25°C for 60 minutes. Next, a laminate sample (2-2) consisting of a primer layer and a resin layer was cut out from the laminate sample (2-1). The laminate sample (2-2) was then immersed in a silicone resin solvent (trade name: e-Solv 21RS, manufactured by Kaneko Chemical Co., Ltd.) to dissolve the silicone rubber in the primer layer. This removed the primer layer from the laminate sample (2-2), and a sample consisting only of the entire thickness of the resin layer was prepared. The loss modulus of the obtained sample was measured in the same manner as in measuring E"(1). From the obtained E" values, E" values ​​at 100°C to 150°C were extracted, and their average value was designated as E"(2).

[0104] The removal of PFPE from the sample obtained by the above operation was confirmed as follows. First, the mass E of the sample was measured. Next, the sample was immersed completely in a beaker containing 200 ml of a separately prepared fluorine-based solvent (trade name: Novec7300, manufactured by 3M). Next, the beaker was placed in a water bath of an ultrasonic cleaning device (trade name: Bransonic (model 2510J-DTH), manufactured by Emerson Japan), and ultrasonic waves were applied for 30 minutes. After treatment, the sample was removed from the beaker and left in an environment at a temperature of 25°C for 60 minutes to dry. The mass F of the dried sample was measured. At this time, it was confirmed that PFPE had been removed from the sample by the fact that (EF) / E was 0.05 or less.

[0105] <Solubility parameter difference> The solubility parameter difference (ΔHSP) between the PFA (PFA-1) used in Example 1 and the compound having vinyl groups at both ends and having the structure represented by the structural formula (7) in the fluoropolymer-forming mixture (FP-1) was 2.8 (MPa). 0.5 ΔHSP was calculated based on the method described above.

[0106] <Evaluation of fixing belt> The obtained fixing belt was subjected to the following evaluations. (Evaluation B-1: Evaluation of toner offset and separation of plain paper and thin paper) The fixing belt was attached to an electrophotographic image forming apparatus (product name: imageRUNNER-ADVANCE C5500, manufactured by Canon Inc.) with the angle of the paper separation claw adjusted. A4 size paper (product name: CHAMEX, manufactured by International Paper Co., Ltd., basis weight 75 g / m) was then applied. 2 An image formation process was carried out to form a 100 mm x 100 mm solid cyan image on a paper sheet. The fixing temperature was 180°C and the paper transport speed was 300 mm / sec. Then, when the number of sheets on which a solid image of cyan color was formed reached 1, 10,000, and 600,000, a process for forming a solid image for evaluation was carried out. 2 A sheet of thin plain paper was passed through the printer, and a solid image for evaluation was formed on the thin plain paper, having a 100 mm x 100 mm cyan solid image area, positioned from the leading edge to the trailing edge of the thin plain paper in the longitudinal direction with a 4 mm margin. If toner adheres to the surface layer of the fixing belt due to toner offset during the fixing of the solid image on the thin plain paper, the toner adhering to the surface layer is transferred to the white background of the thin plain paper after the fixing belt has completed one revolution. Furthermore, if the fixing belt has particularly poor release properties, the thin plain paper will stick to the fixing belt during the fixing process of the solid image for evaluation, making it impossible to form the solid image for evaluation. Therefore, in this evaluation, if a solid image for evaluation could be formed, the solid image for evaluation was visually observed by five evaluators, and the presence or absence of a difference in density between the position where the offset toner was attached and the white area where no toner was attached was evaluated according to the following criteria: Furthermore, if the thin plain paper stuck to the fixing film during the fixing process and a solid image for evaluation could not be formed, it was evaluated as rank D. (Evaluation criteria) Rank A: All five evaluators judged that there was no difference in density. Rank B: Three to four of the five evaluators judged that there was no difference in concentration. Rank C: Three or more of the five evaluators judged that there was a difference in concentration. Rank D: Plain paper Thin paper stuck to the fixing belt, so density difference was not evaluated.

[0107] (Evaluation B-2: Evaluation of scratch resistance) When conveyed paper comes into contact with the fixing member, scratches (paper edge scratches) are likely to occur due to burrs on the edge of the paper. If an unfixed toner image whose fixing area includes the area where the scratched portion of the fixing member abuts is fixed using a fixing member with a paper edge scratch, a difference in glossiness may occur between the area corresponding to the scratched portion and the other areas of the resulting fixed image. Therefore, the scratch resistance of the fixing belt was evaluated through the following experiment. The prepared fixing belt was mounted on an electrophotographic image forming apparatus (product name: imageRUNNER-ADVANCE C5500, manufactured by Canon Inc.), and a first paper (product name: CHAMEX, manufactured by International Paper Co., Ltd., basis weight: 75 g / m 2 The sheets (A4 size, 1000mm x 1000mm) were fed so that their long sides were parallel to the feeding direction. When the number of sheets fed reached 1, 10,000, and 600,000, a second sheet (trade name: OK Topcoat Paper, manufactured by Oji Paper Co., Ltd., basis weight 157 g / m) was fed. 2 A black solid image was formed on the second sheet of paper (A4 size, 100% polyester) by transporting the first sheet of paper so that its short side was parallel to the transport direction. Five evaluators visually inspected each of the three black solid images obtained and evaluated whether there was a difference in gloss between the area corresponding to the long side of the first sheet of paper and the other areas, and ranked them according to the following criteria. (Evaluation criteria) Rank A: All five evaluators judged that there was no difference in gloss. Rank B: Three to four out of five evaluators judged that there was no difference in gloss. Rank C: Three or more of the five evaluators judged that there was a difference in gloss.

[0108] [Examples 2 to 8] The content ratio (mass ratio) of the second PFPE in the mixture A containing the second PFPE and the fluoropolymer-forming mixture used in the impregnation step-2 was changed as shown in Table 1. Except for this, fixing belts Nos. 2 to 8 according to each example were produced in the same manner as in Example 1. In Table 1, "composition" refers to the composition containing the second PFPE and the fluoropolymer (crosslinked product) contained in the pores. The results of evaluations A-1 to A-5 and B-1 to B-2 for the obtained fixing belts Nos. 2 to 8 are shown in Tables 1 and 2.

[0109] [Example 9] A laminate having a resin layer having voids was produced in the same manner as in Example 1, except that the treatment temperature in the impregnation step-1 was set to the temperature shown in Table 1. Furthermore, the impregnation step-2 and subsequent steps were carried out in the same manner as in Example 4 to produce fixing belt No. 9. The results of evaluations A-1 to A-5 and B-1 to B-2 for the obtained fixing belt No. 9 are shown in Tables 1 and 2.

[0110] [Example 10] In the impregnation step-1, PFPE-3 was used as the first PFPE, and the laminate was immersed in the first PFPE heated to 310°C for 1 minute. The temperature of the first PFPE was then reduced at a rate of 6°C per minute, and the laminate was removed when the temperature of the first PFPE reached 250°C. A laminate having a porous resin layer was otherwise prepared in the same manner as in Example 1. The impregnation step-2 and subsequent steps were carried out in the same manner as in Example 4 to prepare fixing belt No. 10. The results of evaluations A-1 to A-5 and B-1 to B-2 for the obtained fixing belt No. 10 are shown in Tables 1 and 2.

[0111] [Example 11] Fixing belt No. 11 was produced in the same manner as in Example 10, except that in the impregnation step-1, the laminate was removed when the temperature of the first PFPE reached 25°C. The results of evaluations A-1 to A-5 and B-1 to B-2 for the obtained fixing belt No. 11 are shown in Tables 1 and 2. Compared to Example 10, the content ratio of the first PFPE in the resin layer is higher, but the content ratios of P2 and the second PFPE are equivalent because volatilization of the first PFPE is suppressed compared to Example 10.

[0112] [Comparative Example 1] In the impregnation step-2, only the second PFPE was introduced into the pores. First, PFPE-2 was mixed with a fluorine-based solvent (trade name: Novec 7300, manufactured by 3M) to prepare a 38% by mass solution of PFPE-2. In the impregnation step-2, the solution was introduced into the pores in the resin layer in the same manner as in Example 1, except that this solution was used. Next, a laminate including a resin layer in which the solution had been introduced into the pores was left in an environment at a temperature of 60°C for 60 minutes to evaporate the fluorine-based solvent in the solution introduced into the pores. The laminate thus obtained, in which only PFPE-2 had been introduced into the pores, was designated as fixing belt No. C-1 according to this comparative example. The results of evaluations A-1, A-2, A-3, A-5, and B-1 to B-2 for this fixing belt No. C-1 are shown in Tables 1 and 2. Note that, since no fluoropolymer was introduced into the pores, evaluation A-4 was not performed.

[0113] [Reference example 1] In the impregnation step-2, only the fluoropolymer-forming mixture was introduced into the pores. That is, the second PFPE was not introduced into the pores. Otherwise, a fixing belt No. R-1 was produced in the same manner as in Example 1. The results of evaluations A-1, A-2, A-3, A-5, and B-1 to B-2 for the obtained fixing belt No. R-1 are shown in Tables 1 and 2. Since no PFPE was introduced into the pores, evaluation A-4 was not performed.

[0114] [Table 1]

[0115] Table 2 shows the evaluation results of the fixing belts produced in Examples 1 to 11, Comparative Example 1 and Reference Example 1.

[0116] [Table 2]

[0117] As shown in Table 2, the fixing members according to the examples were able to achieve both high levels of long-term toner release and scratch resistance, resulting in the formation of high-quality electrophotographic images. On the other hand, the fixing belt according to Comparative Example 1 had a small E"(1) / E"(2) ratio of 0.52. This is thought to be because, in fixing belt No. C-1 according to Comparative Example 1, the second PFPE was filled into the pores without being gelled by the fluoropolymer, causing the second PFPE to interact with the PFA molecules and reducing the viscosity of the PFA. Furthermore, it is thought that the reduced viscosity of the PFA, which serves as the main binder constituting the surface layer, caused paper edge scratches on the outer surface of the surface layer of fixing belt No. C-1 due to long-term image formation.

[0118] The present disclosure includes the following configurations.

[0119] [Configuration 1] A fixing member having an endless belt shape or a roller shape, A base layer and a surface layer, the surface layer contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and has pores that are connected to the openings in the outer surface thereof; perfluoropolyether is contained in at least a portion of the pores; The average value of the loss modulus E" of the surface layer measured at a temperature of 100°C to 150°C and a frequency of 10 Hz in a direction perpendicular to the circumferential direction of the fixing member is defined as E"(1), After removing the perfluoropolyether contained in the pores, when the average value of the loss modulus E" of the surface layer measured at a temperature of 100°C to 150°C and a frequency of 10 Hz in a direction perpendicular to the circumferential direction of the fixing member is defined as E"(2), An anchoring member in which E"(1) / E"(2) is 0.60 or more and less than 1.00.

[0120] [Configuration 2] The fixing member according to Configuration 1, wherein the perfluoropolyether has a structure represented by the following structural formula (2):

[0121] [ka]

[0122] (In structural formula (2), 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 is a positive integer.)

[0123] [Configuration 3] The fixing member according to Configuration 2, wherein the perfluoropolyether has at least one structure selected from the structures represented by the following structural formulas (3) to (6):

[0124] [ka]

[0125] (In structural formula (3), n represents a positive integer, and n is a number within the range that ensures that the viscosity of this perfluoropolyether at a temperature of 40°C is in the range of 30 mPa·s to 500 mPa·s.)

[0126] [ka]

[0127] (In structural formula (4), n' represents a positive integer, and n' is a number within the range that ensures that the viscosity of this perfluoropolyether at a temperature of 40°C is in the range of 10 mPa·s to 2500 mPa·s.)

[0128] [ka]

[0129] (In structural formula (5), m and n'' each independently represent a positive integer, m / n'' is a number that is 0.5 or greater and 2 or less, and m+n'' is a number that provides a viscosity of the perfluoropolyether at a temperature of 40°C in the range of 20 mPa s to 1400 mPa s.)

[0130] [ka]

[0131] (In structural formula (6), m' and n''' each independently represent a positive integer, m' / n''' is a number that is 20 or greater and 1000 or less, and m'+n''' is a number that ensures that the viscosity of this perfluoropolyether at a temperature of 40°C is in the range of 20 mPa·s to 1200 mPa·s.)

[0132] [Configuration 4] The fixing member according to any one of configurations 1 to 3, wherein a composition containing the perfluoropolyether and a fluoropolymer is contained in at least a portion of the pores, and the fluoropolymer has at least one structure of a siloxane T unit and a Q unit, and a repeating unit represented by the following structural formula (1):

[0133] [ka]

[0134] (In structural formula (1), n ​​represents a positive integer.)

[0135] [Configuration 5] 5. The fixing member according to claim 4, wherein the content (mass ratio) of the perfluoropolyether in the composition is 0.20 or more and 0.80 or less. [Configuration 6] 6. The fixing member according to claim 4, wherein the content of the composition relative to the total mass of the surface layer, including the mass of the composition, is 20% by mass or more and 60% by mass or less. [Configuration 7] The fixing member according to any one of configurations 1 to 6, wherein the ratio P2 of the area occupied by the pores to the area of ​​the surface layer (including the pore portion) in a cross section of the surface layer along the circumferential direction of the fixing member (porosity) is 25.0% or more and 60.0% or less. [Configuration 8] 8. The fixing member according to any one of configurations 1 to 7, wherein the openings in the first surface that constitutes the outer surface of the surface layer have an average opening diameter of 1 nm or more and 5 μm or less. [Configuration 9] 9. The fixing member according to any one of configurations 1 to 8, wherein the opening ratio P1 of the first surface constituting the outer surface of the surface layer is 1.0% or more and 15.0% or less. [Configuration 10] 10. The fixing member according to any one of configurations 1 to 9, wherein the thickness of the surface layer is 10 μm or more and 100 μm or less.

[0136] [Configuration 11] A method for producing a fixing member according to any one of configurations 1 to 10, comprising: A method for producing a fixing member, comprising the following steps (i) to (v): Step (i): preparing a laminate having a base layer and a resin layer containing tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA); Step (ii): A step of bringing a first perfluoropolyether heated to a temperature close to the melting point of the PFA into contact with a first surface constituting the outer surface of the resin layer to impregnate the first perfluoropolyether into the resin layer; Step (iii): A step of cooling the laminate obtained in Step (ii), in which the resin layer is impregnated with the first perfluoropolyether, to room temperature; step (iv): removing at least a portion of the first perfluoropolyether impregnated in the resin layer from the first surface side of the resin layer using a fluorine-based solvent to form pores in the resin layer that are open to the first surface of the resin layer; and Step (v): A step of filling at least some of the pores with a mixture containing a second perfluoropolyether and a fluoropolymer-forming mixture, and curing the fluoropolymer-forming mixture.

[0137] [Configuration 12] 11. A fixing device comprising the fixing member according to any one of configurations 1 to 10, and heating means for heating the fixing member. [Configuration 13] 13. The fixing device according to claim 12, wherein the heating means is a heater disposed in contact with the inner circumferential surface of the fixing member. [Configuration 14] 14. An electrophotographic image forming apparatus comprising the fixing device according to claim 12 or 13. [Explanation of symbols]

[0138] 1: Resin part containing PFA 2:Aperture 3: Vacancy 4: Composition containing PFPE and fluoropolymer 101:Outer surface< / pfa>

Claims

1. A fixing member having an endless belt shape or a roller shape, It has a base layer and a surface layer, the surface layer contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer and has pores that are connected to the openings in the outer surface thereof; perfluoropolyether is contained in at least a portion of the pores; The average value of the loss modulus E" of the surface layer measured at a temperature of 100°C to 150°C and a frequency of 10 Hz in a direction perpendicular to the circumferential direction of the fixing member is defined as E"(1), After removing the perfluoropolyether contained in the pores, the average value of the loss modulus E" of the surface layer measured in a direction perpendicular to the circumferential direction of the fixing member at a temperature of 100°C to 150°C and a frequency of 10 Hz is defined as E"(2). A fixing member characterized in that E''(1) / E''(2) is 0.60 or more and less than 1.

00.

2. 2. The fixing member according to claim 1, wherein the perfluoropolyether has a structure represented by the following structural formula (2): 【Chemical 1】 (In structural formula (2), a, b, c, d, e, and f each independently represent 0 or a positive integer, satisfy 1≦a+b+c+d+e+f≦600, and at least one of a, b, c, and d is a positive integer.)

3. The fixing member according to claim 2, wherein the perfluoropolyether has at least one structure selected from the structures represented by the following structural formulas (3) to (6): 【Chemistry 2】 (In structural formula (3), n represents a positive integer, and n is a number in the range that makes the viscosity of this perfluoropolyether at a temperature of 40°C range from 30 mPa·s to 500 mPa·s.) 【Chemistry 3】 (In structural formula (4), n' represents a positive integer, and n' is a number within the range that makes the viscosity of this perfluoropolyether at a temperature of 40°C range from 10 mPa·s to 2500 mPa·s.) 【Chemistry 4】 (In structural formula (5), m and n'' each independently represent a positive integer, m / n'' is a number that is 0.5 or greater and 2 or less, and m+n'' is a number that provides a viscosity of the perfluoropolyether at a temperature of 40°C in the range of 20 mPa s to 1400 mPa s.) 【Chemistry 5】 (In structural formula (6), m' and n''' each independently represent a positive integer, m' / n''' is a number that is 20 or greater and 1000 or less, and m'+n''' is a number that makes the viscosity of this perfluoropolyether at a temperature of 40°C fall within the range of 20 mPa·s to 1200 mPa·s.)

4. 2. The fixing member according to claim 1, wherein the composition containing the perfluoropolyether and the fluoropolymer is contained in at least some of the pores, and the fluoropolymer has at least one structure of a siloxane T unit and a Q unit, and a repeating unit represented by the following structural formula (1): 【Chemistry 6】 (In structural formula (1), n ​​represents a positive integer).

5. The fixing member according to claim 4 , wherein a content ratio (mass ratio) of the perfluoropolyether in the composition is 0.20 or more and 0.80 or less.

6. The fixing member according to claim 4 , wherein a content ratio of the composition to a total mass of the surface layer including the mass of the composition is 20% by mass or more and 60% by mass or less.

7. 2. The fixing member according to claim 1, wherein a ratio P2 of an area occupied by the pores to an area of ​​the surface layer (including the pore portion) in a cross section of the surface layer along the circumferential direction of the fixing member (porosity) is 25.0% or more and 60.0% or less.

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

9. 2. The fixing member according to claim 1, wherein an opening ratio P1 of a first surface constituting the outer surface of the surface layer is 1.0% or more and 15.0% or less.

10. 2. The fixing member according to claim 1, wherein the surface layer has a thickness of 10 [mu]m or more and 100 [mu]m or less.

11. A method for manufacturing the fixing member according to any one of claims 1 to 10, comprising: A method for producing a fixing member, comprising the following steps (i) to (v): Step (i): preparing a laminate having a base layer and a resin layer containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA); Step (ii): A step of bringing a first perfluoropolyether heated to a temperature close to the melting point of the PFA into contact with a first surface constituting the outer surface of the resin layer, thereby impregnating the first perfluoropolyether into the resin layer; Step (iii): A step of cooling the laminate obtained in step (ii), in which the resin layer is impregnated with the first perfluoropolyether, to room temperature; Step (iv): removing at least a portion of the first perfluoropolyether impregnated in the resin layer from the first surface side of the resin layer using a fluorine-based solvent to form pores in the resin layer that are open to the first surface of the resin layer; and Step (v): A step of filling at least some of the pores with a mixture containing a second perfluoropolyether and a fluoropolymer-forming mixture, and curing the fluoropolymer-forming mixture.

12. A fixing device comprising: the fixing member according to any one of claims 1 to 10; and a heating means for heating the fixing member.

13. 13. The fixing device according to claim 12, wherein the heating means is a heater disposed in contact with the inner circumferential surface of the fixing member.

14. An electrophotographic image forming apparatus comprising the fixing device according to claim 12.

Images