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

Abstract

To provide a fixing member that can maintain high toner releasing properties for a longer period of time.SOLUTION: A fixing member comprises a base layer and a surface layer, the surface layer includes a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having a pore communicating with an opening on an outer surface of the surface layer, at least a part of the pore contains a composition containing perfluoropolyether and fluoropolymer, and the fluoropolymer has at least one structure of a T unit and a Q unit of siloxane and a particular repeating unit composed of perfluoropolyether.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.

[0003] 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 sheets. However, because such thin paper has low rigidity, with conventional fixing members, melted toner during thermal fixing adheres to the surface of the fixing member (rotating body), causing the thin paper to wrap around the fixing member. In order to stably form electrophotographic images on thin paper, it is necessary 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]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-140185 [Non-patent literature]

[0005] [Non-Patent Document 1] "Journal of the Japan Adhesion Society", Japan Adhesion Society, 1972, Vol. 8, No. 3, pp. 131-141 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the studies of the present inventors, the fixing member disclosed in Patent Document 1 exhibits excellent toner releasability over a long period of time. However, in the surface layer of the fixing member disclosed in Patent Document 1, the fluorinated oil exists without phase separation from the fluorinated resin (see paragraph

[0019] of Patent Document 1). In this case, there is a limit to the amount of fluorinated oil that can be contained in the surface layer. Therefore, in order to impart excellent toner releasability over a longer period of time to the fixing member, the present inventors recognized that technological development is necessary to provide a fixing member that can retain a larger amount of PFPE and can stably supply the PFPE to its outer surface.

[0007] One aspect of the present disclosure is to provide a fixing member and a manufacturing method thereof that can maintain high toner releasability for 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 for a long period of time. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, there is provided a fixing member having a base layer and a surface layer, wherein the surface layer comprises a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having pores that communicate with openings in the outer surface thereof, and at least some of the pores contain a composition that includes a perfluoropolyether and a fluoropolymer, 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):

[0009] [ka]

[0010] (In structural formula (1), n ​​represents a positive integer.)

[0011] 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.

[0012] According to another aspect of the present disclosure, there is provided a fixing device including the fixing member described above and a heating unit for heating the fixing member.

[0013] 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]

[0014] According to one aspect of the present disclosure, a fixing member capable of maintaining high toner releasability for 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 for a long period of time can be obtained. [Brief explanation of the drawings]

[0015] [Figure 1] 1A and 1B are cross-sectional schematic diagrams of a fixing belt (A) and a fixing roller (B) according to one 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 cross-sectional view of a fixing device using a fixing belt. [Figure 4] FIG. 1 is a cross-sectional view of a fixing device using a fixing roller. [Figure 5] 1 is a schematic cross-sectional view illustrating an electrophotographic image forming apparatus according to one embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0016] 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.

[0017] The present inventors have conducted extensive research to obtain a fixing member that can maintain excellent toner releasability even after long-term use. As a result, they have found that the above-mentioned object can be achieved by having a surface layer containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) having pores that connect to the openings in the outer surface, and by containing a composition containing PFPE and the above-mentioned fluoropolymer in at least some of the pores. The PFA contained in the surface layer has pores that connect to the outer surface, allowing the composition containing PFPE to be contained in the pores. Therefore, the fixing member can retain more PFPE in its surface layer than the surface layer disclosed in Patent Document 1, which retains PFPE in a fluororesin without phase separation.

[0018] Furthermore, as a result of further investigations, the present inventors have found that a composition containing PFPE and the above-mentioned fluoropolymer forms a gel composition and has significantly improved viscosity compared to PFPE. That is, in the above composition, the fluidity of PFPE is significantly suppressed. Furthermore, since the above composition has compression resistance, compression of PFPE caused by deformation of the surface layer during fixing is suppressed. Therefore, excessive migration of PFPE to the outer surface during durability testing can be suppressed. As a result, it is believed that the fixing member according to the present disclosure can maintain excellent toner releasability for a longer period of time compared to conventional fixing members. The fixing member will be described in detail below.

[0019] 1. Fixing member The fixing member may be, for example, a fixing roller, a fixing film, a fixing belt, etc. The fixing member has a base layer and a surface layer. An elastic layer containing silicone rubber may be provided between the base layer and the surface layer. 1(A) and 1(B) are cross-sectional schematic diagrams showing different embodiments of the fixing member according to the present disclosure. Fig. 1(A) shows a fixing member having an endless belt shape (hereinafter also referred to as "fixing belt 11"), and Fig. 1(B) shows a fixing member having a roller shape (hereinafter also referred to as "fixing roller 12"). 1(A) and 1(B) has a base layer 13, an elastic layer 14 that covers the outer surface of the base layer, and a surface layer 15 that covers the surface of the elastic layer opposite to the side facing the base layer. Note that the surface layer 15 may be adhered to the surface of the elastic layer 14 opposite to the side facing the base layer by an adhesive layer (not shown).

[0020] (1) Base layer The material of the base layer 13 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 13. In this case, the material of the base layer 13 may be, for example, nickel, stainless steel, or polyimide, which has excellent heat resistance. The thickness of the base layer 13 is not particularly limited, but is preferably 20 μm or more and 100 μm or less from the viewpoints of strength, flexibility, and heat capacity. In the fixing roller 12, for example, a solid or hollow core is used as the base layer 13. The core may be made of a metal or alloy such as aluminum, iron, or stainless steel. When a hollow core is used, it is possible to provide a heat source inside.

[0021] The outer surface of the base layer 13 may be subjected to a surface treatment to provide adhesion to the elastic layer 14. The surface treatment may be one or a combination of physical treatments such as blasting, lapping, and polishing, and chemical treatments such as oxidation, coupling agent treatment, and primer treatment. When an elastic layer 14 containing silicone rubber is provided on the surface of the base layer 13, it is preferable to apply a primer treatment to the surface of the base layer 13 in order to improve adhesion between the base layer 13 and the elastic layer 14. Examples of the primer used in the primer treatment include paints in which a silane coupling agent, a silicone polymer, a hydrogenated methylsiloxane, an alkoxysilane, a reaction-accelerating catalyst, and a colorant such as red iron oxide are appropriately blended and dispersed in an organic solvent. The primer can be appropriately selected depending on the material of the base layer 13, the type of elastic layer 14, or the form of crosslinking reaction. In particular, when the elastic layer 14 contains a large amount of unsaturated aliphatic groups, a primer containing a hydrosilyl group is preferably used to impart adhesiveness by reacting with the unsaturated aliphatic groups. When the elastic layer 14 contains a large amount of hydrosilyl groups, a primer containing an unsaturated aliphatic group is preferably used. Other examples of primers include those containing alkoxy groups. Commercially available primers can be used. The primer treatment includes a step of applying a primer to the outer surface of the base layer 13 (the surface to be bonded to the elastic layer 14) and drying or baking it.

[0022] (2) Elastic layer The material of the elastic layer 14 is not particularly limited, and any known material used for elastic layers of fixing members can be used. The elastic layer 14 preferably contains silicone rubber, which has excellent heat resistance. Addition-curing liquid silicone rubber is preferably used as the raw material for the silicone rubber. The elastic layer contains silicone rubber that has poor chemical affinity with PFPE, which is advantageous because the PFPE contained in the surface layer is less likely to migrate to the elastic layer even with long-term use, and is instead supplied primarily to the surface of the fixing member. The thickness of the elastic layer 14 can be appropriately designed taking into consideration the surface hardness of the fixing member and the width of the fixing nip portion to be formed. When the fixing member is a fixing belt 11, the thickness of the elastic layer 14 is preferably 100 μm to 500 μm, and more preferably 200 μm to 400 μm. When the fixing member is a fixing roller 12, the thickness of the elastic layer 14 is preferably 0.1 mm (100 μm) to 3.0 mm, and more preferably 0.3 mm (300 μm) to 2.0 mm. By setting the thickness of the elastic layer 14 within this range, a sufficient width of the fixing nip portion can be ensured when the fixing member is incorporated into a fixing device.

[0023] The elastic layer 14 may contain a filler. The filler is added to control thermal conductivity, heat resistance, and elastic modulus. Specific examples of the filler include silicon carbide (SiC), silicon nitride (Si3N4), silica (SiO2), boron nitride (BN), aluminum nitride (AlN), alumina (Al2O3), iron oxide (Fe2O3), zinc oxide (ZnO), magnesium oxide (MgO), titanium oxide (TiO2), copper (Cu), aluminum (Al), silver (Ag), iron (Fe), nickel (Ni), carbon black (C), carbon fiber (C), and carbon nanotubes (C).

[0024] (3) Surface layer The surface layer 15 contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). Furthermore, the pores of the PFA contain a composition containing perfluoropolyether (PFPE) and the above-mentioned fluoropolymer. As shown in FIG. 2(B), the surface layer 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 contacts unfixed toner on a recording medium during fixing. Here, the pores 3 preferably do not have a shell. That is, the walls of the pores 3 are preferably composed of a solid portion of the surface layer, specifically, a resin portion 1 containing PFA. At least a portion of the pores 3 contains a composition 4 containing perfluoropolyether (PFPE) and a fluoropolymer. As shown in FIG. 2(C), for example, the pores 3 are filled with a composition 4 containing PFPE and a fluoropolymer.

[0025] 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.

[0026] When the fixing member is an endless belt-shaped fixing member, 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, and 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. By setting P2 to 25.0% or more, a larger amount of PFPE can be retained in the surface layer. As a result, stable toner releasability can be imparted to the first surface over a longer period of time. On the other hand, by setting P2 to 60.0% or less, wear caused by an excessive number of pores in the surface layer can be more effectively prevented. The porosity can be calculated from a cross section along the circumferential direction of the fixing member of the surface layer from which the second PFPE contained in the pores in the surface layer of the fixing belt according to the present disclosure has been removed, or of the resin layer from which the first PFPE has been removed, obtained after the pore formation process described below.

[0027] 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.

[0028] 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.

[0029] <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, and more preferably 290°C to 310°C. As the PFA, commercially available products can be used, and specific examples are given below. "451HP-J", "959HP-Plus", "350-J", "950HP-Plus" (all product names, manufactured by Mitsui Chemours Fluoroproducts); "P-66P", "P-66PT", "P-802UP" (all product names, manufactured by AGC); "AP-230", "AP-231SH", etc. (all product names, manufactured by Daikin Industries, Ltd.); "6502N" (product name, manufactured by 3M).

[0030] <Perfluoropolyether (PFPE)> The PFPE contained in at least some of the pores will be described in detail. The PFPE contained in the composition contained in the pores may be referred to as a "second PFPE" to distinguish it from the PFPE (first PFPE) used in forming 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.

[0031] [ka]

[0032] 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.

[0033] 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 VPF16256, 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).

[0034] [ka]

[0035] (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.)

[0036] [ka]

[0037] (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.)

[0038] [ka]

[0039] (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.)

[0040] [ka]

[0041] (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.)

[0042] 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 preferably a PFPE having a structure represented by the above structural formula (4).

[0043] The viscosity of the second PFPE contained in the pores at a temperature of 40°C is preferably 500 mPa·s or more and 2500 mPa·s or less, more preferably 1000 mPa·s or more and 2000 mPa·s or less. 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.

[0044] 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).

[0045] 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. 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 described below.

[0046] <Fluoropolymer> The fluoropolymer contained in at least some of the pores will now be described in detail. The fluoropolymer in the present disclosure has a repeating unit represented by the following structural formula (1), and further has at least one structure of a siloxane T unit and a siloxane Q unit. The structure represented by structural formula (1) is common to the perfluoroalkyl ether structure of PFPE. Therefore, the fluoropolymer having the structure represented by structural formula (1) has a high affinity with PFPE. In addition, the siloxane T unit 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).

[0047] [ka]

[0048] In structural formula (1), n ​​represents a positive integer. 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.

[0049] 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) below. The viscosity of this compound is not particularly limited, but from the viewpoint of ensuring good fluidity of the mixture when filling the pores in the surface layer with a mixture of the second PFPE and the fluoropolymer-forming mixture, it is preferable that the viscosity at a temperature of 23°C is 0.50 Pa·s to 40.0 Pa·s, for example. 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.

[0050] [ka]

[0051] 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).

[0052] [ka]

[0053] [ka]

[0054] 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.

[0055] 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 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.

[0056] [ka]

[0057] 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 -C6H5). 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.

[0058] 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.

[0059] 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.

[0060] 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)

[0061] [ka]

[0062] 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.).

[0063] 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.

[0064] The fuser member according to 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 PFPE in the surface layer migrates relatively quickly to the first surface of the surface layer. On the other hand, in the fixing member according to 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 believed 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 provide 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.

[0065] 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. If the mass 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 smoothly carried out. Furthermore, if the mass 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 of the second PFPE can be measured. The content ratio (mass 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.

[0066] The content ratio 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, 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.

[0067] The mixture of the second PFPE and the fluoropolymer-forming mixture has fluidity, so it can be easily introduced into the pores of the resin that constitutes the surface layer. In the present disclosure, PFA, which has high chemical affinity with the fluoropolymer and PFPE, is used as the resin, so the mixture can be easily introduced throughout the entire thickness of the PFA.

[0068] The solubility parameter difference (ΔHSP) between the mixture 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 can be introduced into the pores more smoothly.

[0069] 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)

[0070] Here, when the fluoropolymer-forming mixture contains a compound having a structure represented by the structural formula (7), the only substantial structural difference between the compound and the second PFPE is that unsaturated aliphatic groups are bonded to both ends of the compound. Therefore, the SP values ​​of the compound and the second PFPE determined by the above method are almost the same. Furthermore, since the compound is the main component in the fluoropolymer-forming mixture, the SP value of the compound or the SP value of the second PFPE can be used as the SP value of the mixture containing the fluoropolymer-forming mixture and the second PFPE.

[0071] <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 the following steps (i) to (v): The elastic layer formed on the outer peripheral surface of the base layer can be provided as needed. Step (i): preparing a laminate including a base layer having an endless belt shape or a roller shape, an elastic layer on the outer peripheral surface of the base layer, and a resin layer containing PFA on the outer peripheral surface of the elastic layer; Step (ii): A step of contacting a first perfluoropolyether (first PFPE) heated to a temperature close to the melting point of PFA with a surface (first surface) of the resin layer opposite to the surface facing the elastic layer, thereby impregnating the resin layer with the first PFPE; 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 some of the pores contain the composition comprising the second PFPE and a fluoropolymer.

[0072] 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.

[0073] 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, causing the first PFPE impregnated near the first surface side of the resin layer to 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 is reduced. Accordingly, in step (iv) described below, the volume of voids formed by removing the first PFPE from the resin layer is relatively reduced. Therefore, when a first PFPE with low viscosity is used, the resin layer is preferably removed from the first PFPE bath after the temperature of the PFPE bath has been cooled to at least the melting point of PFA (specifically, for example, 296° C.), preferably 250° C., more preferably room temperature, thereby preventing the resin layer from shrinking when removed from the PFPE bath.

[0074] 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. 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.

[0075] In step (ii), the first PFPE is impregnated so that the content of the first PFPE relative to the total mass of the resin layer impregnated with the first PFPE is preferably 25% by mass to 60% by mass, more preferably 30% by mass to 55% by mass. If the content 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 of the first PFPE is 60% by mass or less, a decrease in mechanical strength due to an 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.

[0076] 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, when a first PFPE with a low viscosity is used, it is preferable to perform step (iii) in a PFPE bath to avoid shrinkage of the resin layer in step (iii).

[0077] 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).

[0078] 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.

[0079] 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 having a first PFPE content of 33% by mass can be produced. Furthermore, the resin layer 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 having 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 having a first PFPE content of 60% by mass can be obtained, assuming the other conditions are the same as above. The reason why the content of the first PFPE in the resin layer is 2% higher by mass when the resin layer is removed from the PFPE bath after cooling the temperature of the PFPE bath to 25°C than when the resin layer is removed from the PFPE bath after cooling the temperature to 250°C is thought to be as follows: That is, when the resin layer is removed from the PFPE bath after cooling the temperature of the PFPE bath to 25°C, volatilization of the first PFPE from the resin layer is suppressed. Note that, unless the resin layer shrinks, volatilization of the first PFPE after the resin layer is removed from the PFPE bath does not affect the volume of pores in the resin layer formed through step (iv).

[0080] 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.

[0081] In the preparation of a fixing member, any method can be used to contact the resin layer with the first PFPE, as long as it can contact 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, an elastic 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 elastic 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.

[0082] 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, examples of the "solvent capable of dissolving the first PFPE" include solvents that dissolve 10 g or more of the first PFPE per 100 g of solvent at 25° C. On the other hand, examples of the "solvent that does not dissolve PFA" include solvents that dissolve 1 g or less of PFA per 100 g of solvent at 25° C. Examples of the fluorine-based solvent that can dissolve the first PFPE but does 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 preferable in order to promote the removal of the first PFPE from the resin layer.

[0083] 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, an elastic layer containing silicone rubber, 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 X°C and the melting point of PFA is Y°C, XY (°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, when a first PFPE with a low viscosity is used, step (iii) is preferably performed in a PFPE bath to avoid volatilization of the first PFPE in step (iii) and a decrease in the amount of PFPE in the resin layer due to 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.

[0084] Step (v-1): The laminate having the resin layer having voids obtained through the above step is immersed in a mixture of the second PFPE and the fluoropolymer-forming mixture for preferably 5 to 30 minutes, more preferably 10 to 30 minutes (e.g., 15 minutes), thereby impregnating the voids in the resin layer with the mixture (impregnation step-2). The temperature of the mixture at this time is preferably a temperature at which curing of the fluoropolymer-forming mixture does not proceed easily during impregnation. As a non-limiting example, the temperature of the mixture in this step is preferably 0°C or higher and preferably 100°C or lower. The temperature of the mixture is more preferably 50°C or lower.

[0085] Step (v-2): The laminate obtained through step (v-1) is removed from the mixture, and the mixture adhering to the outer surface is removed. Next, the fluoropolymer-forming mixture in the mixture introduced into the pores is cured to form a fluoropolymer. This results in a fixing member according to one embodiment of the present disclosure containing a composition (preferably a gel composition) containing a second PFPE and a fluoropolymer in at least some of the pores. In this step, the method for removing the excess mixture adhering to the outer surface is not particularly limited, but examples thereof include washing with a fluorine-based solvent, removing with air, and wiping with a nonwoven fabric. Examples of the method for washing with a fluorine-based solvent include removing the mixture using fibers such as nonwoven fabric impregnated with a fluorine-based solvent. Examples of fluorine-based solvents include hydrofluoroether (trade name: Novec 7300, manufactured by 3M). The heating temperature and heating time for curing can be selected so as to achieve a desired reaction rate of the reactive components in the fluoropolymer-forming mixture. The heating temperature is preferably in the range of 100°C to 250°C, 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.

[0086] In order to obtain high-quality images with high glossiness on a variety of paper media, the surface free energy of the fixing member is set to 13.0 mJ / m 2 ~15.0mJ / m 2 The surface free energy can be measured using a contact angle meter (for example, product name: DM-501, manufactured by Kyowa Interface Science Co., Ltd.).

[0087] 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.

[0088] (1) Fixing device using a fixing belt FIG. 3 is a cross-sectional view of a fixing device including a fixing belt 11 for heating and an elastic pressure roller 19, taken along the circumferential direction of the fixing belt. The fixing belt 11 is a fixing belt according to one embodiment of the present disclosure. The fixing belt 11 is loosely fitted around a belt guide member 16. A pressure rigid stay 18 is inserted inside the belt guide member 16. The belt guide member 16 is formed 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 17 is provided as a heat source at the position where the belt guide member 16 and the inner surface of the fixing belt 11 come into contact. The ceramic heater 17 is fitted into and fixed in a groove provided along the longitudinal direction of the belt guide member 16. The ceramic heater 17 generates heat when electricity is applied by means not shown. The elastic pressure roller 19 has an elastic layer 19b made of hardened silicone rubber provided on the circumferential surface of a stainless steel core 19a. A surface layer 19c made of fluororesin is provided on the circumferential surface of the elastic layer 19b. The thickness of the surface layer 19c is, for example, 50 μm. A downward pressure force is applied to the rigid pressure stay 18 by compressing pressure springs (not shown) between both ends of the rigid pressure stay 18 and spring bearing members (not shown) on the device chassis side. As a result, the lower surface of the ceramic heater 17 disposed on the lower surface of the belt guide member 16 and the upper surface of the elastic pressure roller 19 are pressed against each other with the fixing belt 11 sandwiched therebetween, forming a predetermined fixing nip N. In other words, the lower surface of the ceramic heater 17 is disposed in contact with the inner circumferential surface of the fixing belt 11. A recording medium P, which serves as 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 to be fixed on the recording medium P.

[0089] (2) Fixing device using a fixing roller FIG. 4 is a cross-sectional view taken along the circumferential direction of a fixing roller in a fixing device that includes a fixing roller 12 for heating, an elastic pressure roller 19 arranged opposite the fixing roller 12, and a heater 20 that is a heating means for the fixing roller 12. The fixing roller 12 is a fixing roller according to one embodiment of the present disclosure. The fixing roller 12 has an elastic layer 14 formed on the outer peripheral surface of a hollow core metal serving as a base layer 13, and a surface layer 15 further formed on the outer surface thereof. The fixing roller 12 and the elastic pressure roller 19 are rotatably pressed against each other by a pressure means (not shown), forming a fixing nip N. Inside the fixing roller 12 and the elastic pressure roller 19, a heater 20 is installed as a heat source to supply the heat necessary to melt the unfixed toner G. A halogen heater is generally used as the heater 20. In some cases, multiple halogen heaters are installed inside according to the size of the recording medium P being conveyed. A rotational force is applied to the fixing roller 12 and the elastic pressure roller 19 by means not shown through the base layer (metal core) 13 and the end of the metal core 19a, and the rotation is controlled so that the moving speed of the surface of the fixing roller 12 is approximately equal to the conveying speed V of the recording medium P. In this case, the rotational force may be applied to either the fixing roller 12 or the elastic pressure roller 19, and the other may be rotated by being driven, or the rotational force may be applied to both. The recording medium P, which is the heated object and on which an image is formed with unfixed toner G, is sandwiched and conveyed through the fixing nip N of the fixing device thus formed. This heats and pressurizes the toner image. As a result, the toner image melts and mixes colors, and is then cooled, thereby fixing the toner image on the recording medium P.

[0090] 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.

[0091] 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. By applying the fixing devices illustrated in Figures 3 and 4 to the fixing section 35 of the electrophotographic image forming apparatus illustrated in Figure 5, an image forming apparatus can be obtained that can provide high-quality images with excellent image uniformity. [Example]

[0092] 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.

[0093] (PFA) PFA-1: "959HP-Plus" (product name, manufactured by Mitsui Chemours Fluoroproducts, melting point = 296°C) PFA-2: "451HP-J" (product name, manufactured by Mitsui Chemours Fluoroproducts, melting point = 305°C) (perfluoropolyether) PFPE-1: "Krytox GPL-104" (trade name, manufactured by Chemours, viscosity: 111 mPa·s (40°C)) PFPE-2: "Krytox GPL-107" (trade name, manufactured by Chemours, viscosity: 851 mPa·s (40°C)) PFPE-3: "Krytox VPF-16256" (product name, manufactured by Chemours, viscosity: 1403 mPa s (40℃)) PFPE-4: "Krytox XHT-1000" (trade name, manufactured by Chemours, viscosity: 1941 mPa·s (40°C)) PFPE-5: "Fomblin M100" (product name, manufactured by Solvay Specialty Polymers Japan, viscosity: 1327 mPa·s (40°C)) PFPE-6: "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))

[0094] [Example 1] <Production of fixing belt> [Preparation of a laminate having a base layer, an elastic layer, and a resin layer containing PFA] As the base layer, a substrate having an endless belt shape made of electroformed nickel with an inner diameter of 30 mm, a width of 400 mm, and a thickness of 40 μm was prepared. The outer peripheral surface of this substrate was treated with a primer. The raw material for forming the elastic layer was an addition-curing liquid silicone rubber (product name: SE1886, manufactured by Dow Corning Toray Co., Ltd.) containing no filler. To 61 parts by volume of this liquid silicone rubber, 38 parts by volume of spherical alumina (product name: Alnabeads CB-A30S, manufactured by Showa Denko K.K.) was added as a spherical filler, and 1 part by volume of vapor-grown carbon fiber (product name: VGCF-S, manufactured by Showa Denko K.K., aspect ratio = 100, average fiber length = 10 μm) was added as an irregular-shaped filler. The addition-curable silicone rubber composition for forming the elastic layer was prepared in this manner and applied to the outer peripheral surface of the base layer by ring coating, followed by heating at 200°C for 4 hours to crosslink the addition-curable silicone rubber composition layer and form an elastic layer 300 μm thick. The base layer on which the elastic layer was formed was rotated in the circumferential direction at a speed of 20 mm / sec, and the surface of the elastic layer was irradiated with ultraviolet light in an atmospheric environment using an ultraviolet lamp positioned 10 mm away from the surface of the elastic layer. The ultraviolet lamp used was a low-pressure mercury ultraviolet lamp (product name: GLQ500US / 11, manufactured by Toshiba Lighting & Technology Corporation), and the integrated light intensity of the 185 nm wavelength on the irradiated surface was 800 mJ / cm. 2 UV light was irradiated so that Next, an addition-curing silicone rubber adhesive (product name: SE1819CV, a mixture of equal amounts of "liquid A" and "liquid B" manufactured by Dow Corning Toray Co., Ltd.) was applied approximately uniformly to a thickness of 20 μm on the surface of the elastic layer. Next, a fluororesin tube (PFA-1, melting point 296°C, thickness 20 μm) with its inner surface treated for hydrophilicity was placed over the belt, and the belt surface was uniformly rubbed from above the fluororesin tube to remove excess adhesive from between the elastic layer and the fluororesin tube. The base layer, which was then coated with the elastic layer and fluororesin tube, was then placed in an electric furnace set at 200°C and heated for 1 hour to harden the adhesive and bond the fluororesin tube to the elastic layer. Both ends were then cut to obtain an endless laminate with a width of 343 mm.

[0095] [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 an insulating material and heated to a temperature of 310° C. The laminate prepared above was attached to a dipping device, immersed in the heated first PFPE for 1 minute, and then removed.

[0096] (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 an elastic layer and a resin layer was cut out from the laminate. Then, the laminated sample was immersed in a silicone resin dissolving agent (trade name: e-solv 21RS, manufactured by Kaneko Chemical Co., Ltd.) to dissolve the silicone rubber in the elastic layer, thereby removing the elastic 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 relative to the resin layer containing the first PFPE was calculated. Apparatus: TGA851 (trade name, manufactured by METTLER TOLEDO) Atmosphere: In air Temperature: 425℃ In the profile of measurement time-weight loss rate obtained by above-mentioned thermogravimetric analysis, the slope becomes constant, and the linear least squares approximation formula is obtained from the region where only PFA decreases.Then, the intercept of this linear least squares approximation formula is set as PFA content ratio (mass%), and calculate the first PFPE content ratio (mass%) = 100 - PFA content ratio.

[0097] (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 voids 3 were observed on the obtained laminate. It was also observed that the voids 3 had openings 2 that connected to the first surface 101.

[0098] (Evaluation A-2: Calculation of the 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 process from which the first PFPE had been removed, i.e., the surface of the resin layer opposite the side facing the elastic 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 binarized using the image processing software to obtain a binary image. The binarization process used the YEN method to distinguish between the portions corresponding to the openings and the portions corresponding to the PFA in the SEM image. The ratio of the number of pixels in the portions corresponding to the openings to the number of pixels in the entire image was then 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).

[0099] 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 an observation area measuring 8 μm in length and 11 μm in width was obtained. The resolution was set to 717 pixels in length and 986 pixels in width so that voids appearing in the cross-section could be recognized. The obtained SEM image was binarized using numerical calculation software (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 surface 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 surface and the second surface of the surface 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 surface layer toward the first surface, and the long side of the observation area is parallel to the second surface.

[0100] 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.

[0101] (Impregnation process-2) Next, the laminate having a resin layer having 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-3) 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 0.19. The obtained mixture A was placed in a borosilicate glass measuring cylinder. The second PFPE was dissolved in the fluoropolymer-forming mixture, and mixture A was a transparent liquid. Next, the laminate was attached to a dipping device, and the entire laminate was immersed in mixture A for 30 minutes and then removed. The immersion was carried out at room temperature (25°C). Next, the mixture A adhering to the outer surface of the laminate removed from the mixture A was removed using a nonwoven fabric impregnated with a fluorine-based solvent (product name: Novec 7300, manufactured by 3M). 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-3 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 resulting fixing belt in the circumferential direction, observed using 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.

[0102] (Evaluation A-3: Content ratio of the composition containing the second PFPE and the fluoropolymer in the surface layer) A measurement sample consisting of only the entire thickness of the surface layer was obtained from the obtained fixing belt in the same manner as described above. This measurement sample was measured using a thermogravimetric analyzer (TGA) under the following conditions, and the content ratio (mass%) of the composition containing the second PFPE and the fluoropolymer in the pores to the total mass of the surface layer, including the mass of the composition, 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.

[0103] (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 for a fixing belt having a surface layer whose pores were filled with a composition containing a second PFPE and a fluoropolymer in the same manner 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. After treatment, 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.

[0104] (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.

[0105] The obtained fixing belt was subjected to the following evaluations B-1 and B-2. (Evaluation B-1: Toner offset and separation of regular 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 belt, 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 offset to the surface layer of the fixing belt during the fixing of the solid image on the thin plain paper, the toner would be transferred to the white background of the thin plain paper after the fixing belt had made one revolution. Furthermore, the fixing belt had poor release properties, and during the fixing process of the solid image for evaluation, the thin plain paper would stick to the fixing belt, making it impossible to form a solid image for evaluation. Therefore, in this evaluation, if a solid image for evaluation could be formed, the solid image for evaluation was visually inspected by five evaluators to check for any difference in density between the position where the offset toner was attached and the white area where no toner was attached, and evaluated according to the following criteria: In addition, 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.

[0106] (Evaluation B-2: Measurement of surface free energy) In evaluation B-1, the surface free energy of the outer surface of the fixing belt immediately before forming a solid image on thin plain paper was calculated using the "Kitazaki-Hata method" described in Non-Patent Document 1. Specifically, the contact angles of water, n-hexadecane, and diiodomethane were measured on the outer surface of the fixing belt (measurement environment: temperature 23°C, relative humidity 55%). Next, using the measurement results of each contact angle, the surface free energy was calculated from the "extended Fowkes equation" according to the theory of Kitazaki and Hata (Non-Patent Document 1). A contact angle meter (trade name: DM-501, manufactured by Kyowa Interface Science Co., Ltd.) was used for the measurement, and analysis software (trade name: FAMAS, manufactured by Kyowa Interface Science Co., Ltd.) was used for the surface free energy analysis.

[0107] [Examples 2 to 9] Fixing belts according to Examples 2 to 9 were produced in the same manner as in Example 1, except that a mixture obtained by changing the ratio of the second PFPE in mixture A of the second PFPE and the fluoropolymer-forming mixture was used as the mixture to be introduced into the pores in the impregnation step-2. The results of evaluations A-1 to A-4 and B-1 to B-2 for each of the obtained fixing belts are shown in Tables 1 and 2.

[0108] [Example 10] 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, a fixing belt was produced in the same manner as in Example 5 from the impregnation step-2 onwards. The results of evaluations A-1 to A-4 and B-1 to B-2 of the obtained fixing belt are shown in Tables 1 and 2.

[0109] [Examples 11 to 13] A fixing belt was produced in the same manner as in Example 5, except that the second PFPE type used in the impregnation step-2 was changed as shown in Table 1. The results of evaluations A-1 to A-4 and B-1 to B-2 of the obtained fixing belt are shown in Tables 1 and 2.

[0110] [Example 14] A laminate having a resin layer having voids was produced in the same manner as in Example 1, except that the type of PFA used to form the surface layer and the treatment temperature in the impregnation step-1 were changed as shown in Table 1. A fixing belt was produced in the same manner as in Example 5 from the impregnation step-2 onwards. The results of evaluations A-1 to A-4 and B-1 to B-2 of the obtained fixing belt are shown in Tables 1 and 2. The difference in solubility parameter (ΔHSP) between the PFA species (PFA-2) used in this example 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 4.6 (MPa). 0.5 It was.

[0111] [Example 15] In the impregnation step-1, PFPE-6 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. From the impregnation step-2 onward, a fixing belt was prepared in the same manner as in Example 5. The results of evaluations A-1 to A-4 and B-1 to B-2 for the obtained fixing belt are shown in Tables 1 and 2.

[0112] [Example 16] A laminate having a resin layer having voids was produced in the same manner as in Example 15, except that in the impregnation step-1, the laminate was immersed in a first PFPE heated to 310°C for 1 minute and removed when the temperature of the first PFPE reached 25°C. A fixing belt was produced in the same manner as in Example 5 from the impregnation step-2 onwards. The results of evaluations A-1 to A-4 and B-1 to B-2 of the obtained fixing belt are shown in Tables 1 and 2.

[0113] [Comparative Example 1] A laminate having a base layer, an elastic layer, and a resin layer containing PFA was prepared in the same manner as in Example 1, and this was used as a fixing belt according to this comparative example. The prepared fixing belt was subjected to evaluations B-1 and B-2 described in Example 1. The results of evaluations B-1 and B-2 are shown in Tables 1 and 2. Note that the fixing belt according to this comparative example was not subjected to evaluations A-1 to A-4 because it did not undergo impregnation steps 1 and 2.

[0114] Comparative Example 2 A laminate having a resin layer impregnated with the first PFPE was prepared in the same manner as in Example 1, except that the type of the first PFPE and the treatment temperature in the impregnation step-1 were changed as shown in Table 1. Next, the operation of removing the first PFPE from the resin layer was performed in the same manner as in Example 1. However, the first PFPE in the resin layer could not be removed, and pores could not be formed in the resin layer. This is thought to be because the amount of the first PFPE impregnated was small, so the PFPE impregnated in the resin layer did not aggregate or bond, and the PFPE penetrated between PFA molecules, preventing it from being eluted with a solvent. Therefore, the impregnation step-2 was not performed, and the laminate having a resin layer containing the first PFPE was used as the fixing belt of this comparative example. The results of evaluations A-1 and B-1 to B-2 for this fixing belt are shown in Tables 1 and 2. As described above, pores could not be formed in the resin layer, and therefore the impregnation step-2 could not be performed. Therefore, evaluations A-2 to A-4 were not performed.

[0115] Comparative Example 3 In the impregnation step-2, only the second PFPE was introduced into the pores. First, PFPE-3 was mixed with a fluorine-based solvent (trade name: Novec 7300, manufactured by 3M) to prepare a 38% by mass solution of PFPE-3. 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 was 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-3 was introduced into the pores, was used as the fixing belt according to this comparative example. The results of evaluations A-1 to A-3 and B-1 to B-2 for this fixing belt are shown in Tables 1 and 2. Note that, since no fluoropolymer was introduced into the pores, evaluation A-4 was not performed.

[0116] Comparative Example 4 A fixing belt was produced in the same manner as in Example 1, except that only the fluoropolymer-forming mixture was introduced into the pores in the impregnation step-2. The results of evaluations A-1 to A-3 and B-1 to B-2 for the obtained fixing belt are shown in Tables 1 and 2. Note that, since no PFPE was introduced into the pores, evaluation A-4 was not performed.

[0117] [Table 1]

[0118] Table 2 shows the results of evaluations B-1 and B-2 of the fixing belts produced in Examples 1 to 16 and Comparative Examples 1 to 4.

[0119] [Table 2]

[0120] As shown in Table 2, the fixing members according to the examples can maintain excellent toner releasability even after long-term use, and as a result, it has been found that high-quality electrophotographic images can be formed.

[0121] The present disclosure includes the following configurations.

[0122] [Configuration 1] A fuser member having a base layer and a surface layer, the surface layer contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having pores that connect to the openings in the outer surface thereof; At least some of the pores contain a composition containing a perfluoropolyether and a fluoropolymer, 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):

[0123] [ka]

[0124] (In structural formula (1), n ​​represents a positive integer.)

[0125] [Configuration 2] The fixing member according to Configuration 1, wherein the perfluoropolyether has a structure represented by the following structural formula (2):

[0126] [ka]

[0127] (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.)

[0128] [Configuration 3] The fixing member according to Configuration 2, wherein the perfluoropolyether has at least one structure selected from the group consisting of the following structural formulas (3) to (6):

[0129] [ka]

[0130] (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.)

[0131] [ka]

[0132] (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.)

[0133] [ka]

[0134] (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.)

[0135] [ka]

[0136] (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.)

[0137] [Configuration 4] The fixing member according to any one of configurations 1 to 3, wherein the fixing member has an endless belt shape, and the ratio 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 5] 5. The fixing member according to any one of configurations 1 to 4, wherein the content of the composition relative to the total mass of the surface layer, including the mass of the composition in the pores, is 20% by mass or more and 60% by mass or less. [Configuration 6] 6. The fixing member according to any one of configurations 1 to 5, wherein the content ratio (mass ratio) of the perfluoropolyether in the composition is 0.20 or more and 0.80 or less. [Configuration 7] 7. The fixing member according to any one of configurations 1 to 6, wherein the viscosity of the perfluoropolyether at 40° C. is 1000 mPa·s or more and 2500 mPa·s 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 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.

[0138] [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.

[0139] [Configuration 12] 11. A fixing device comprising the fixing member according to any one of configurations 1 to 10, and a heating means for heating the fixing member. [Configuration 13] 13. The fixing device according to claim 12, wherein the fixing member is a fixing belt having an endless belt shape, and the heating means is a heater disposed in contact with the inner circumferential surface of the fixing belt. [Configuration 14] 14. An electrophotographic image forming apparatus comprising the fixing device according to claim 12 or 13. [Explanation of symbols]

[0140] 1: Resin part containing PFA 2:Aperture 3: Vacancy 4: Composition containing PFPE and fluoropolymer 101:Outer surface< / pfa>

Claims

1. A fuser member having a base layer and a surface layer, the surface layer contains a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer having pores that connect to the openings in the outer surface thereof; At least some of the pores contain a composition containing a perfluoropolyether and a fluoropolymer, The fixing member is characterized in that 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): 【Chemical 1】 (In structural formula (1), n ​​represents a positive integer).

2. 2. The fixing member according to claim 1, wherein the perfluoropolyether has a structure represented by the following structural formula (2): 【Chemistry 2】 (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 group consisting of the following structural formulas (3) to (6): 【Chemistry 3】 (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 4】 (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 5】 (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 6】 (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 fixing member has an endless belt shape, and the ratio 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.

5. 2. The fixing member according to claim 1, wherein the content of the composition relative to the total mass of the surface layer, including the mass of the composition in the pores, is 20% by mass or more and 60% by mass or less.

6. The fixing member according to claim 1 , wherein a content ratio (mass ratio) of the perfluoropolyether in the composition is 0.20 or more and 0.80 or less.

7. 2. The fixing member according to claim 1, wherein the viscosity of the perfluoropolyether at 40[deg.] C. is 1000 mPa.s or more and 2500 mPa.s 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. The fixing member according to claim 1 , wherein the opening ratio of the 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 unit for heating the fixing member.

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

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

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