CN117270354A

CN117270354A - Fixing film, method of manufacturing the same, heat fixing device, and electrophotographic image forming apparatus

Info

Publication number: CN117270354A
Application number: CN202310739100.5A
Authority: CN
Inventors: 浅香明志; 川原龙之介
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2022-06-21
Filing date: 2023-06-21
Publication date: 2023-12-22

Abstract

The invention relates to a fixing film, a method for manufacturing the same, a heating fixing device and an electrophotographic image forming apparatus. A fixing film having a ring shape, the fixing film comprising at least a base material, an elastic layer, and a release layer in this order, wherein the release layer is composed of a tube containing a fluororesin, and when the ratio of the maximum X-ray diffraction intensity Ic of the release layer in the region of 2 theta=17 to 19 DEG with respect to the maximum X-ray diffraction intensity Ia of 2 theta=39.5 to 40.5 DEG by a reflection X-ray diffraction method is X, the length in the rotation axis direction of the fixing film is L, the average value of X in the region from both ends to 0.15L in the rotation axis direction of the fixing film is Xe, and the average value of X in the region of 0.70L in the center in the rotation axis direction of the fixing film between the both ends to 0.15L is Xm, the ratio of Xe to Xm is 1.20 or more.

Description

Fixing film, method of manufacturing the same, heat fixing device, and electrophotographic image forming apparatus

Technical Field

The present disclosure relates to a fixing film used in an electrophotographic image forming apparatus, a method of manufacturing the same, a heat fixing apparatus, and an electrophotographic image forming apparatus.

Background

An electrophotographic image forming apparatus includes a fixing device that fixes a toner image on a recording material such as paper (hereinafter, sometimes referred to as "paper") by heating and pressurizing the toner image. The fixing device includes a fixing member such as a heat roller (heat film) and a pressure roller (pressure film), and performs fixing processing of unfixed toner images on paper at a position (fixing nip portion) where the heat roller and the pressure roller are pressed against each other.

As an example of the fixing device, there is a thin film heating type device. The device is provided with a heater as a heating member (heating source) having a resistance heating element on a ceramic substrate. The device has an annular fixing film as a heating member which is wrapped in a heater and which rotates while being in contact with the heater. The apparatus has a pressing roller (pressing rotator) as a nip forming member that forms a nip by pressing against the fixing film and rotationally drives the fixing film.

In this film heating system, since the fixing film can be reduced in heat capacity and size, the fixing device can be made energy-saving. In addition, it is possible to shorten the time (warm-up time) required for the temperature of the fixing film to reach a prescribed temperature sufficient for heat fixing the toner image.

As the film-shaped substrate, a resin such as polyimide, a metal such as nickel or stainless steel is used. An elastic layer containing a rubber having excellent heat resistance such as silicone rubber is provided on the base material. When the sheet having the elastic layer and the toner transferred thereon passes through the nip portion, the surface of the fixing member deforms to satisfactorily follow the unfixed toner image on the sheet due to the flexibility of the elastic layer, whereby the contact area between the fixing member and the unfixed toner image on the sheet expands. Therefore, the unfixed toner image can be fused and fixed to the paper more uniformly, and as a result, a high-quality electrophotographic image can be obtained.

In order to impart releasability to the toner of the fixing member, a release layer is provided on the elastic layer. As a material constituting the release layer, a fluororesin such as Polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP) is used.

As a method of forming a release layer on an elastic layer, a method of coating the surface of the elastic layer with a fluororesin-containing tube (hereinafter also referred to as "fluororesin tube") produced by pre-extrusion molding is known. However, in the case of the fluororesin tube, the molecules of the fluororesin are oriented in the extrusion direction thereof. As a result, the fluororesin tube is likely to crack in the direction of orientation of the molecular chains, that is, in the direction parallel to the extrusion direction.

In japanese patent laid-open publication No. 2011-197507, a heat shrinkable tube obtained by expanding a PFA tube is heated to shrink the tube, and the tube is welded and integrated with a rubber roller to form a PFA layer on the outer peripheral surface of the rubber roller, and then the PFA is reheated to a temperature equal to or higher than the melting point of PFA contained in the PFA tube. The internal stress of the PFA layer formed by the PFA tube after heat shrinkage is released and removed, and cracking of the PFA layer in the direction of the rotation axis of the roller or belt is prevented.

Disclosure of Invention

At least one embodiment of the present disclosure aims to provide a fixing film having a ring shape, which has a surface layer, and which combines crack resistance in the direction along the rotation axis and abrasion resistance in the end regions on both sides in the direction along the rotation axis at a higher level even when used for a long period of time.

Further, at least one embodiment of the present disclosure aims to provide a heat fixing device that contributes to stable formation of high-quality electrophotographic images.

Further, at least one embodiment of the present disclosure aims to provide an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images.

At least one embodiment of the present disclosure is directed to a method for producing a fixing film having a surface layer, which combines, even when used for a long period of time, cracking resistance in a direction along a rotation axis and abrasion resistance in end regions on both sides in the direction along the axis at a higher level.

According to at least one aspect of the present disclosure, there is provided a fixing film having a ring shape, the fixing film having at least a base material, an elastic layer, and a release layer in this order,

the release layer is constituted of a tube containing a fluororesin,

the ratio (Ic/Ia) of the maximum X-ray diffraction intensity Ic of 2 theta=17 to 19 DEG relative to the maximum X-ray diffraction intensity Ia of 2 theta=39.5 to 40.5 DEG of the release layer by the reflection X-ray diffraction method is set as X,

The length of the fixing film along the direction of the rotation axis is L,

The average value of X in the end regions from the two ends to 0.15L along the direction of the rotation axis of the fixing film is Xe,

When the average value of X in the central region of the fixing film, which is 0.70L in length as the central portion in the direction along the rotation axis, existing between the regions from the both end portions to 0.15L is taken as Xm,

the ratio of Xe to Xm (Xe/Xm) is 1.20 or more.

In addition, according to at least one embodiment of the present disclosure, there is provided a heat fixing device having the above fixing film.

Further, according to at least one aspect of the present disclosure, there is provided an electrophotographic image forming apparatus including the above-described heat fixing device.

Further, according to at least one aspect of the present disclosure, there is provided a method for manufacturing a fixing film, including:

(i) A step of preparing a fluororesin tube which is a cylindrical extrusion molded article of a resin mixture containing a fluororesin;

(ii) Coating the outer surface of the elastic layer of the base material with the fluororesin tube; and

(iii) And a step of heat-treating the region of the fluororesin tube corresponding to the central region at a temperature equal to or higher than the melting temperature of the fluororesin, and heat-treating the region of the fluororesin tube corresponding to the end region at a temperature not exceeding the melting temperature of the fluororesin.

Exemplary embodiments are described below with reference to the drawings to illustrate further features of the present disclosure.

Drawings

FIG. 1 is a schematic view showing an example of an electrophotographic image forming apparatus

Fig. 2 is a schematic cross-sectional view showing the configuration of the fixing device of the present embodiment

FIG. 3 is a schematic cross-sectional view of a fixing film according to the present embodiment

FIG. 4 shows an example of an X-ray diffraction pattern of the fluororesin release layer according to the present embodiment

FIG. 5 is a schematic view showing a measurement site by a reflection X-ray diffraction method

Detailed Description

In the present disclosure, "XX or more and YY or less" and "XX to YY" representing numerical ranges are intended to include numerical ranges including lower and upper limits as endpoints unless otherwise specified. When numerical ranges are described in stages, the upper limit and the lower limit of each numerical range may be arbitrarily combined.

According to the study of the present inventors, it was confirmed that: in the PFA layer in which the internal stress is released by the method described in japanese patent laid-open No. 2011-197507, the molecular orientation in the extrusion direction (direction along the rotation axis) of the PFA tube is relaxed, and cracking along the rotation axis is less likely to occur. Here, as disclosed in japanese patent application laid-open No. 2010-143118, the degree of orientation of the fluororesin is associated with the degree of crystallinity. Therefore, the fluororesin tube having a high degree of molecular orientation in the direction along the rotation axis has high crystallinity and excellent abrasion resistance. Therefore, the abrasion resistance of the fluororesin tube in which the molecular orientation of the fluororesin in the direction along the rotation axis is relaxed is also reduced by the method described in japanese patent laid-open No. 2011-197507.

In response to the demand for further longer life of recent electrophotographic image forming apparatuses, improvement in durability is also demanded for fixing films. Further, since the end regions of both sides of the fixing film in the direction along the rotation axis are portions that repeatedly contact the edges of the paper, particularly high abrasion resistance is required.

As a result of intensive studies, the present inventors have found that it is possible to achieve both of the cracking resistance and the abrasion resistance at a higher level by differentiating the orientation state of the molecules of the fluororesin in the release layer between the central region of the fixing film along the direction of the rotation axis (hereinafter also referred to as "longitudinal direction") which corresponds approximately to the image forming region of the recording material and the end regions on both sides along the direction of the axis which correspond approximately to the region where the ends of the recording material are in contact.

That is, the fixing film of at least one embodiment of the present disclosure includes at least a base material, an elastic layer, and a release layer in this order.

The release layer is constituted of a tube containing a fluororesin (hereinafter also referred to as "fluororesin tube").

The length of the fixing film along the direction of the rotation axis is L,

The average value of X in the region from the two ends of the fixing film in the direction of the rotation axis to 0.15L (hereinafter also referred to as "end region") was defined as Xe,

When the average value of X in a region (hereinafter also referred to as "central region") of the fixing film having a length of 0.70L as a central portion in the direction along the rotation axis direction, which is present between end regions ranging from 0.15L to the both end portions, is set to Xm,

The ratio of Xe to Xm (Xe/Xm) is 1.20 or more.

In the graph of the X-ray diffraction peak of the fluororesin tube measured by the reflection X-ray diffraction method, the maximum peak observable in the range of 2θ=17 to 19 ° is considered to be a diffraction peak based on the α -type crystal (100) plane of the fluororesin in the fluororesin tube. In the above graph, a halo pattern (halo pattern) observable in the range of 2θ=30 to 50 ° is considered to originate from an amorphous (amorphous) component of the fluororesin in the fluororesin tube.

Therefore, in the present disclosure, in the above chart, the maximum X-ray diffraction intensity at 2θ=39.5 to 40.5 ° in the amorphous halation peak is set as Ia. In the above chart, ic is the maximum X-ray diffraction intensity of the diffraction peak of the α -type crystal (100) plane derived from the fluororesin, which is 2θ=17 to 19 °. Further, as a parameter indicating the degree of progress of crystallization in the fluororesin tube, a value (X) of the ratio of Ic to Ia (Ic/Ia) is set.

In order to exclude the influence of the baseline, ic and Ia are values obtained by subtracting the X-ray diffraction intensity at 2θ=59 to 60 ° from the reference.

The ratio (Xe/Xm) of X, that is, xe in the end regions of the fluororesin tube, to X, that is, xm in the central region of the fluororesin tube according to one embodiment of the present disclosure is 1.20 or more. That is, the degree of crystallization of the fluororesin in the end regions of the fluororesin tube is higher than that in the central region. Thus, the fluororesin tube of the present disclosure is less likely to cause cracking in the direction along the rotation axis even when used for a long period of time in the central region. In addition, the wear resistance is high in the end region which is easily contacted with the edge portion of the paper. As a result, the fixing film of at least one embodiment of the present disclosure combines cracking resistance in the direction along the rotation axis and abrasion resistance in the end regions on both sides in the direction along the rotation axis at a higher level even when used for a long period of time.

Embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

Electrophotographic image forming apparatus (image forming apparatus)

Fig. 1 is a schematic view showing an outline of an example of an electrophotographic image forming apparatus (hereinafter, also referred to as an image forming apparatus). The image forming apparatus is an electrophotographic image forming apparatus, and includes a rotating electrophotographic photoreceptor 101. The image forming apparatus includes a charging device 102 and an image exposing unit 103 as electrostatic latent image forming means for the photoreceptor 101, and a developing unit 104 for developing the electrostatic latent image on the photoreceptor 101 in the form of a toner image (developer image). Further, the image forming apparatus includes a transfer unit 105 that transfers the toner image on the photoconductor 101 to a sheet-like recording material (hereinafter referred to as paper or sheet) P. The image forming apparatus includes a cleaning unit 106 for cleaning the surface of the photoreceptor 101 after transfer of the toner image, a heating and fixing device (fixing device) 10 (fig. 2) as a fixing unit for fixing the toner image T on the sheet P, and the like.

[ heating fixing device (fixing device) ]

Fig. 2 is a schematic cross-sectional view showing a general configuration of the fixing device 10 in the present embodiment. In the following description, the direction along the rotation axis refers to a direction orthogonal to the conveyance direction of the paper on the surface of the paper with respect to the fixing device and the members constituting the fixing device. The length refers to the dimension along the direction of the axis of rotation. The direction along the rotation axis of the fixing film is also a direction orthogonal to the paper conveyance direction, and in fig. 2, a direction perpendicular to the surface on which the fixing film 20 is drawn (a direction perpendicular to the drawing).

The fixing device 10 is a belt (film) heating type fixing device. A ceramic heater (hereinafter referred to as a heater) 1 as a heating body and a film guide 2 serving also as a heating body supporting member are provided. Further, a fixing film 20 having a ring shape (cylindrical shape) and flexibility and heat resistance is provided as a heating member (fixing member). Further, a pressing roller 30 is provided as a nip forming member that forms a nip (fixing nip) N by being pressed against the fixing film 20.

The heater 1 is a slender plate-like member extending along the longitudinal direction (direction perpendicular to the drawing) of the fixing film 20, and has a heat generating source such as a resistance heat generating body that generates heat by being energized by a power supply unit (not shown), and rapidly increases in temperature by power supply. The temperature of the heater 1 is detected by a temperature detecting means not shown, and the detected temperature information is input to a control means not shown. The control unit controls the power supplied from the power supply unit to the heat generating source so as to maintain the detected temperature input from the temperature detection unit at a predetermined fixing temperature, and adjusts the temperature of the heater 1 to the predetermined temperature.

The heater 1 is supported by a film guide 2, and the film guide 2 is formed of a heat-resistant material having rigidity into a groove () shape having a substantially semicircular arc shape in cross section. More specifically, a groove 2a is provided along the guide long side on the outer surface of the film guide 2, and the heater 1 is fitted into the groove 2a.

As described later, the fixing film 20 includes, at least, a ring-shaped (tubular) base material 21, an elastic layer 22, a release layer 24, and the like in this order from the inside to the outside (fig. 3). As shown in fig. 3, the fixing film 20 may further have other layers such as an inner surface sliding layer 25, a primer layer 26, and the like. The fixing film 20 is a ring-shaped film having an inner peripheral surface that rubs against the heater 1 and the film guide 2 in a use state, and is fitted around an outer peripheral surface of the film guide 2 supporting the heater 1 with a margin in the peripheral surface.

The heater 1 and the pressure roller 30 sandwich the fixing film 20 and press-contact each other, and a nip portion N is formed between the fixing film 20 and the pressure roller 30. The pressure roller 30 is driven to rotate at a predetermined circumferential speed in a counterclockwise direction indicated by an arrow R30 by a rotation driving device M such as a motor. The fixing film 20 is rotated in the clockwise direction of the arrow R20 by the outer periphery of the film guide 2 while being slid while being in close contact with the surface of the heater 1 by the inner surface thereof, following the rotation drive of the pressure roller 30. The ends of both sides of the fixing film 20 in the direction of the rotation axis are rotatably supported by flanges (not shown) as restricting members fixed to the fixing device 10.

The film guide 2 functions as a supporting member of the heater 1, and also functions as a rotation guide member of the fixing film 20. In order to ensure the slidability of the heater 1 and the film guide 2, the inner peripheral surface of the fixing film 20 is coated with a lubricant (grease).

The pressure roller 30 includes a solid round bar-shaped or cylindrical (tubular) substrate 31, an elastic layer 32, and a release layer 33 from the inside to the outside. The pressing roller 30 is rotationally driven in use by a rotational driving device M such as a motor. Therefore, the ends of both sides of the base 31 in the direction of the rotation axis are rotatably supported by a fixing portion, not shown, such as a frame of the fixing device 10 via bearing members.

The pressing roller 30 is disposed at a position facing the fixing film 20 between the heater 1 supported by the film guide 2. Then, the pressure roller 30 is brought into pressure contact with the fixing film 20 by applying a predetermined pressure to the pressure roller 30 and the fixing film 20 by a pressure mechanism (not shown), whereby the elastic layers (22, 32) are elastically deformed. Thereby, a nip portion N having a predetermined width is formed between the pressure roller 30 and the fixing film 20 in relation to the sheet conveying direction.

The pressure contact between the fixing film 20 as the heating member and the pressure roller 30 as the nip forming member may be a configuration in which the pressure roller 30 is pressed against the fixing film 20 with a predetermined pressure, or a configuration in which the fixing film 20 is pressed against the pressure roller 30. Further, both the fixing film 20 side and the pressure roller 30 may be pressed against each other with a predetermined pressure.

When the pressure roller 30 is rotationally driven by the rotational driving device M, the sheet P is conveyed while being sandwiched between the nip portion N with the fixing film 20 that is rotationally driven. Further, the fixing film 20 is heated by the heater 1 until the surface reaches a predetermined temperature (for example, 200 ℃). In this state, the sheet P carrying the unfixed toner image T is introduced into the nip portion N and is nipped and conveyed, and thereby the unfixed toner T on the sheet P is heated and pressurized. Since the unfixed toner T is melted and mixed in this way, the toner image is then fixed to the paper P as a fixed image by cooling the unfixed toner T.

[ fixing film ]

Next, the fixing film 20 in this embodiment will be described in detail.

Fig. 3 is a schematic sectional view showing the layer constitution of the fixing film 20. Reference numeral 21 denotes a base material (cylindrical base) of the fixing film 20, 25 denotes an inner surface sliding layer disposed on the inner peripheral surface of the base material 21, 26 denotes a primer layer covering the outer peripheral surface of the base material 21, and 22 denotes an elastic layer disposed on the primer layer 26. Reference numeral 24 denotes a fluororesin tube as a release layer, and 23 denotes an adhesive layer for fixing the release layer 24 to the elastic layer 22.

The constituent layers are specifically described below.

(3-1) substrate 21

The base material 21 of the fixing film 20 has a ring shape. In view of the heat resistance and bending resistance required for the base material, for example, a heat resistant resin such as polyimide, polyamideimide, polyether ether ketone (PEEK) or the like can be suitably used, and in view of heat conductivity, a metal such as stainless steel (SUS), nickel alloy or the like having a higher heat conductivity than the heat resistant resin can be suitably used. The base material 21 needs to have a reduced heat capacity and an improved mechanical strength, and therefore, the thickness is desirably 5 to 100 μm, preferably 20 to 85 μm.

(3-2) inner sliding layer 25

The fixing film 20 includes an inner surface sliding layer 25 on the inner peripheral surface side of the base 21.

The inner slide layer 25 is preferably a resin having both high durability and high heat resistance, such as polyimide resin. In this example, a polyimide precursor solution obtained by reacting an aromatic tetracarboxylic dianhydride or a derivative thereof with an aromatic diamine in an organic polar solvent in approximately equimolar amounts was applied to the inner peripheral surface of the base material 21, and the solvent was dried, and then heated to perform a dehydration ring-closure reaction (imidization reaction) to form the inner sliding layer 25. The inner sliding layer 25 is preferably formed to have a thickness capable of functioning as a sliding layer sufficiently during durability in use, because it gradually wears away by friction with the heater 1. On the other hand, when excessively thickened, it acts as a heat-resistant layer that impedes the heat supply from the heater 1. Therefore, the thickness is preferably 5 to 20. Mu.m, more preferably 10 to 15. Mu.m.

(3-3) elastic layer 22

An elastic layer 22 is provided on the outer peripheral surface of the base material 21 with a primer layer 26 interposed therebetween. The elastic layer 22 uniformly applies heat to the unfixed toner T so as to wrap the unfixed toner T on the sheet P as the sheet P passes through the nip portion N. By causing the elastic layer 22 to function in this way, a high-quality image with high gloss and no fixing unevenness can be obtained.

The material of the primer layer 26 is not particularly limited, and a known material may be used. Examples thereof include "DY39-051A/B" (trade name) manufactured by Dow Toray Co.Ltd. The thickness of the primer layer 26 is not particularly limited, and is, for example, 0.1 to 5 μm. The method for forming the primer layer 26 is not particularly limited, and examples thereof include spray coating and dip coating.

The material of the elastic layer 22 is not particularly limited, and a known material can be used. The cured product of the addition reaction crosslinking type liquid silicone rubber is preferable because it is easy to process, can be processed with high dimensional accuracy, and hardly generates reaction by-products when heat curing. The addition reaction crosslinking type liquid silicone rubber contains, for example, organopolysiloxane and organohydrogen polysiloxane, and may further contain a catalyst and other additives. The organopolysiloxane is a base polymer prepared from silicone rubber, and preferably has a number average molecular weight of 5 to 10 thousands and a weight average molecular weight of 1 to 50 thousands.

The liquid silicone rubber is a polymer having fluidity at room temperature, is cured by heating, has a moderately low hardness after curing, and has sufficient heat resistance and deformation recovery force. Therefore, the liquid silicone rubber is suitably used not only for the belt elastic layer 22 but also for the elastic layer 32 of the pressure roller 30 described later.

In addition, if the elastic layer 22 is formed solely of silicone rubber, the thermal conductivity of the elastic layer 22 becomes low. It is preferable to improve the thermal conductivity of the elastic layer 22, to make the heat generated by the heater 1 easily spread to the paper P through the fixing film 20, and to sufficiently heat and suppress image defects such as fixing unevenness when fixing the toner to the paper P. Therefore, in order to improve the thermal conductivity of the elastic layer 22, it is preferable that a high thermal conductivity filler having high thermal conductivity, for example, a granular form, is mixed and dispersed in the elastic layer 22.

As the granular high thermal conductivity filler, a filler selected from the group consisting of silicon carbide (SiC), zinc oxide (ZnO), and aluminum oxide (Al ₂ O ₃ ) At least one of the group consisting of aluminum nitride (AlN), magnesium oxide (MgO), carbon, and the like. These may be used singly or in combination of 2 or more.

The average particle diameter of the filler having high thermal conductivity is preferably 1 μm or more and 50 μm or less from the viewpoint of handling and dispersibility. The shape may be spherical, pulverized, needle-like, plate-like, whisker-like, or the like, and is preferably spherical from the viewpoint of dispersibility. In order to obtain a good quality image with sufficient elasticity and to make the time from heating to a predetermined temperature good by heat capacity, the thickness of the elastic layer 22 is preferably 30 to 500 μm, more preferably 100 to 300 μm.

(3-4) adhesive layer 23

An adhesive layer 23 for fixing a fluororesin tube as a release layer 24 is formed on the cured silicone rubber as the elastic layer 22. The adhesive layer 23 may be formed by, for example, coating the surface of the elastic layer 22 with a thickness of 1 to 10 μm (adhesive coating step of coating the outer peripheral surface of the cylindrical elastic layer with an adhesive).

The adhesive layer 23 is, for example, a cured product of an addition-curable silicone rubber adhesive. The addition-curable silicone rubber adhesive 23 contains an addition-curable silicone rubber compounded with a self-adhesive component. Specifically, the catalyst composition contains an organopolysiloxane having an unsaturated hydrocarbon group represented by a vinyl group, a hydrogen organopolysiloxane, and a platinum compound as a crosslinking catalyst. And is cured by an addition reaction.

The adhesive used for the adhesive layer 23 is not particularly limited, and may be selected in consideration of the materials of the elastic layer and the release layer, and a known adhesive may be used.

(3-5) Release layer 24

The release layer is composed of a fluororesin tube. The fluororesin tube is preferably a cylindrical extrusion molded product, for example. As the release layer as the surface layer of the fixing member, for example, a fluororesin tube based on extrusion molding can be used from the viewpoints of moldability and toner releasability. As the fluororesin, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) excellent in heat resistance can be suitably used. For example, the release layer is preferably an extrusion molded tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA tube).

The copolymerization form of PFA as a raw material is not particularly limited, and examples thereof include random copolymerization, block copolymerization, graft copolymerization, and the like. The molar ratio of Tetrafluoroethylene (TFE) to perfluoroalkyl vinyl ether (PAVE) in PFA as a raw material is not particularly limited. For example, a raw material having a TFE/PAVE molar ratio of 94/6 to 99/1 can be suitably used.

In addition to PFA, tetrafluoroethylene/hexafluoropropylene copolymer (FEP), polytetrafluoroethylene (PTFE), ethylene/tetrafluoroethylene copolymer (ETFE) may be mentioned as the fluororesin. In addition, polychlorotrifluoroethylene (PCTFE), ethylene/chlorotrifluoroethylene copolymer (ECTFE), polyvinylidene difluoride (PVDF), and the like can be exemplified. Further, 1 or a combination of a plurality of these fluorine resins may be used.

The thickness of the release layer 24 is preferably 10 μm or more in order to maintain the function as the release layer during durability in consideration of abrasion due to friction with paper. On the other hand, if the thickness is excessively increased, the heat efficiency is reduced due to an increase in heat resistance, and the thermal contact resistance with paper is increased due to a lack of flexibility, so that the energy saving property and the image quality are reduced, and therefore, the thickness is preferably 45 μm or less. For example, the thickness of the release layer is preferably 10 to 45. Mu.m, 10 to 40. Mu.m, 15 to 40. Mu.m.

In this example, as the fluororesin tube, a tube (hereinafter also referred to as "PFA tube") made of PFA having a thickness of 15 to 40 μm by extrusion molding was used. The inner surface of the PFA tube is preferably subjected to sodium treatment, excimer laser treatment, ammonia treatment, or the like in advance. This is because the wettability with the addition-curable silicone rubber adhesive and the adhesiveness after curing can be improved.

The release layer 24 is formed by coating a PFA tube on the outer peripheral surface of the elastic layer 22 coated with the addition-curable silicone rubber adhesive 23 using a known technique. In the examples described later, a method of vacuum-expanding and coating a PFA tube from the outside (vacuum-expanding coating method) was used.

Between the PFA tube after coating and the elastic layer 22, there are an extra addition-curable silicone rubber adhesive 23 that does not contribute to adhesion and air that is trapped during tube coating. To squeeze out the excess adhesive 23 and air, the excess adhesive 23 and air are removed using the following method: a method of extruding the fixing film by moving the fixing film in the longitudinal direction while ejecting air from an annular nozzle slightly larger than the outer diameter of the fixing film; an O-ring extrusion method or the like, which is smaller than the outer diameter of the fixing film, is used.

Next, the addition-curable silicone rubber adhesive 23 is cured and bonded by heating for a predetermined time by a heating means such as an electric furnace, and both end portions are cut to a desired length, whereby a fixing film can be obtained.

The fixing film of one embodiment of the present disclosure changes the crystal orientation state of the release layer 24 according to the position along the direction of its rotation axis. An example of a specific manufacturing method of such a fixing film will be described. In the heat treatment of the release layer (fluororesin tube), a cylindrical heating cylinder capable of being heated to a temperature of 330 ℃ or higher is used to heat the entire region of the fixing film. In the embodiment described later, the outer diameter of the fixing filmCorrespondingly, a heating cartridge with an inner diameter of +.>Is provided. The inner surface of the heating cylinder is coated with heat-resistant black paint.

Further, the belt heater is provided by dividing the heating cylinder into at least 3 parts up, down, so that the heating temperature can be changed and controlled according to the position along the axial direction of the fixing film. Thermocouples capable of independently controlling and adjusting temperature are installed in each belt heater. Thus, the heating treatment is performed by controlling the heating temperature to be different in the direction along the axis of the fixing film, so that the crystal orientation state of the release layer 24 is different in the region corresponding to the end regions on both sides in the direction along the axis and in the region corresponding to the central region. The molecules of the fluororesin tube, which is a cylindrical extrusion molded product of a resin mixture containing the fluororesin, are oriented in the extrusion direction. Therefore, in the fixing film having the elastic layer coated with the fluororesin tube, the molecules of the fluororesin are oriented in the direction along the rotation axis of the fixing film in the release layer formed of the fluororesin tube.

For such a fluororesin tube, for example, it is preferable to heat a region corresponding to an end region of the fixing film from both ends in the direction of the rotation axis to 0.15L at a temperature not exceeding the melting temperature of the fluororesin. For example, when the fluororesin is PFA, the heat treatment temperature of the region corresponding to the end region is preferably 100 to 250 ℃, more preferably 120 to 200 ℃, and even more preferably 140 to 170 ℃.

Further, it is preferable to heat-treat a central region of 0.70L in length, which is a central portion in the direction along the rotation axis, between regions of the fixing film ranging from both end portions to 0.15L so as to be equal to or higher than the melting temperature of the fluororesin. For example, when the fluororesin is PFA, the heat treatment temperature is preferably 280 to 400 ℃, more preferably 300 to 350 ℃, and even more preferably 310 to 330 ℃.

The heating time may be a time period in which the temperature of the release layer can sufficiently reach a desired temperature, and examples thereof include 1 to 20 minutes, 1 to 10 minutes, 2 to 5 minutes, and the like.

In the present disclosure, the ratio (Ic/Ia) of the maximum X-ray diffraction intensity Ic of 2θ=17 to 19° to the maximum X-ray diffraction intensity Ia of 2θ=39.5 to 40.5° of the release layer by the reflection X-ray diffraction method is set as X.

The length of the fixing film in the direction of the rotation axis is L, the average value of X in the end regions of the fixing film from the both ends in the direction of the rotation axis to the length of 0.15L is Xe, and the average value of X in the central region of the fixing film, which is the length of 0.70L in the central portion in the direction of the rotation axis, between the both ends to the length of 0.15L is Xm (fig. 5). At this time, the ratio of Xe to Xm (Xe/Xm) is 1.20 or more.

As described above, a value of Xe/Xm of 1.20 or more means: the crystallinity of the end regions is higher than that of the central region of the release layer, which is associated with the molecular orientation during extrusion molding. A value of Xe/Xm of 1.20 or more means: the orientation crystallinity of the end regions is higher than that of the central region. That is, in the end region, the molecular orientation of the fluororesin in the direction along the rotation axis by the cylinder extrusion molding is maintained more excellent. Therefore, it is considered that the end region is less likely to wear even when it contacts the end (edge portion) of the paper. In addition, when the value of Xe/Xm is 1.20 or more, the orientation of the central portion, that is, the region through which the toner-bearing sheet passes is relatively low. That is, in the central region within 1 fluororesin tube, the molecular orientation of the fluororesin in the direction along the rotation axis by the cylinder extrusion molding is relaxed or vanished. The heat transferred by the heater in contact with the inner peripheral surface of the fixing film tends to be easily transferred in the direction of orientation of the molecules of the fluororesin. Therefore, in the central region where the orientation of the fluororesin in the direction along the rotation axis is relaxed or vanished, heat is difficult to transfer in the direction along the rotation axis and is easy to transfer in the thickness direction. As a result, the heating efficiency of the unfixed toner on the paper is improved in the central region, and the energy saving performance is improved. In addition, since the crystallinity of the fluororesin is low, the flexibility is also improved, and the occurrence of cracks can be suppressed.

The value of Xe/Xm is preferably 1.20 to 5.00, more preferably 1.23 to 4.20. In addition, the content may be 1.25 to 2.00.

The value of Xe/Xm can be increased by heating the central portion of the fixing film coated with the PFA tube having high oriented crystallinity at the time of extrusion molding to a temperature equal to or higher than the melting point of PFA.

The value of Xe/Xm can be reduced by, for example, not performing the heat treatment or reducing the difference between the heating temperatures at the center and both ends during the heat treatment.

The Xe is, for example, preferably in the range of 35.0 to 62.0, particularly preferably in the range of 37.0 to 50.0, and further preferably in the range of 37.0 or more and less than 50.0.

Xm is, for example, preferably in the range of 10.0 to 35.0, particularly preferably in the range of 10.0 to 31.0, further preferably 10.0 or more and less than 31.0.

By setting Xe and Xm to each of the above ranges, the in-plane orientation of the crystal can be controlled to be small, and cracking of the release layer during use can be more easily suppressed.

Xe can be increased by improving the orientation of the PFA tube during extrusion molding. In addition, xe can be reduced by reducing the orientation at the time of extrusion molding.

Like Xe, xm can be increased by improving the orientation of the PFA tube during extrusion molding. In addition, xm can be reduced by heat-treating the central portion of the fixing film at a temperature equal to or higher than the melting point of PFA.

According to at least one aspect of the present disclosure, a fixing film provided with a release layer that can stably exhibit excellent energy saving performance while maintaining abrasion resistance with paper and improving crack resistance can be obtained. In addition, according to at least one aspect of the present disclosure, a heat fixing device that contributes to stably forming high-quality electrophotographic images can be obtained. Further, according to at least one aspect of the present disclosure, an electrophotographic image forming apparatus capable of stably forming high-quality electrophotographic images can be obtained.

Examples

Hereinafter, the present disclosure will be described with reference to examples and comparative examples described below. The present invention is not limited to these examples.

First, a method of evaluating physical properties will be described.

[ measurement of crystallinity of release layer: reflection X-ray diffraction method ]

The alignment of the crystallinity release layer 24 of the fluororesin in the central region and the end regions of the release layer formed of the fluororesin tube was evaluated by measuring the X-ray diffraction pattern obtained from the sample by the reflection method and the diffraction intensity thereof using an X-ray diffraction apparatus. The measurement conditions of the X-ray diffraction are shown below.

X-ray diffraction device: miniFlex600 (manufactured by Physics Co., ltd.)

Tube voltage/current output: 40kV/15mA

An X-ray source: cuK alpha (0.154184 nm)

Kβ filter: ni filter

Scanning axis: theta/2 theta linkage

2 theta scan range: 3-60 DEG

θ/2θ axis step angle: 0.02 ° (2. Theta.)

Fig. 4 shows an example of the X-ray diffraction pattern obtained by the above measurement. The maximum X-ray diffraction intensity of the diffraction peak of the α -type crystal (100) plane occurring at 2θ=17 to 19 ° was set to Ic. The maximum intensity of the wide amorphous halation peak (maximum X-ray diffraction intensity of 2θ=39.5 to 40.5°) occurring at 2θ=30 to 50 ° was defined as Ia. The ratio of x=ic/Ia is used as an index of crystallinity and orientation. In order to exclude the influence of the baseline, ic and Ia are values obtained by subtracting the X-ray diffraction intensity at 2θ=59 to 60 ° from the reference.

Further, X-ray diffraction measurement of the release layer 24 was performed every 10mm in length in the direction along the rotation axis of the fixing film, and X at each measurement position was calculated. The 4-point measurement positions were equally provided in the circumferential direction at positions of every 10mm in length along the direction of the rotation axis.

As shown in fig. 5, when the length of the fixing film 20 in the direction along the rotation axis (arrow 501 in fig. 5) is L, the average value of X in the region (end region) having a length of 0.15L at each end in the direction along the rotation axis is Xe. Further, the average value of X in the central region of length 0.70L of the central portion in the direction of the rotation axis, which is sandwiched between the end regions of length 0.15L from the both side ends in the direction of the rotation axis, was taken as Xm.

Next, a method for evaluating the fixing film will be described.

[ durability evaluation ]

< wear resistance of end region >

The durability evaluation of the fixing film 20 was performed using the film heating type fixing device 10 shown in fig. 2, which incorporated each of the fixing films of examples and comparative examples. A4-size paper (trade name: GF-C068; manufactured by Canon Co., ltd.) was passed through 50 ten thousand sheets continuously at a speed of 70 sheets per minute in the transverse direction in a state where the pressing force was 156.8N at one end side and the total pressing force was 313.6N (32 kgf) and the moving speed (peripheral speed) of the pressing roller surface was 320mm/sec, and the surface temperature of the paper passing portion of the fixing film was adjusted to 170 ℃. The portion of the end region of the fixing film, which passed through 50 ten thousand sheets of paper, where the edge portion of the paper was in contact with was visually observed, and the abrasion resistance of the end region was evaluated according to the following criteria.

Class a: no contact mark was confirmed on the edge of the paper.

Class B: the contact trace of the edge portion of the paper was confirmed.

Grade C: the disappearance of the surface layer was confirmed locally at the abutting portion of the edge portion of the paper.

< cracking resistance of Central region >

A fixing device similar to the fixing device used for the evaluation of the abrasion resistance of the end region was separately prepared. The fixing device was mounted on an electrophotographic image forming apparatus (trade name: imageRUNNER ADVANCE DX C5870F; manufactured by Canon Co., ltd.). Then, A4-size paper (trade name: GF-C068; manufactured by Canon Co., ltd.) was passed through 50 ten thousand sheets continuously at a speed of 70 sheets per minute in the lateral direction. Then, each 10 ten thousand sheets of A4-size paper were passed through 1 sheet of coated paper (quotient Name: OK Topcoat 128g/m ² The method comprises the steps of carrying out a first treatment on the surface of the SRA3 size (320 mm. Times.450 mm) manufactured by Wako paper Co., ltd.) forms a black lattice-like image on the entire surface of the coated paper. Then, the obtained 5 black lattice images were visually observed, and evaluated according to the following criteria.

Class a: no flaw or sharp streak due to the cracking of the release layer in the direction along the rotation axis of the fixing film (PFA tube extrusion direction) was confirmed on the black lattice image.

Class B: on the black grid-like image, flaws and sharp streaks caused by the cracking of the release layer in the direction along the rotation axis of the fixing film (PFA tube extrusion direction) were confirmed.

[ evaluation of energy saving Property ]

A fixing device similar to the fixing device used for the evaluation of the abrasion resistance of the end region was separately prepared. The fixing device was mounted on an electrophotographic image forming apparatus (trade name: imageRUNNER ADVANCE DX C5870F; manufactured by Canon Co., ltd.) and the surface temperature of the paper passing portion of the fixing film was adjusted to 170℃in an environment having a temperature of 10℃and a relative humidity of 50%. Using this electrophotographic image forming apparatus, a black lattice image was formed on the entire surface of an A4-size paper (trade name: GF-C068; manufactured by Canon Co., ltd.). The A4 size paper was continuously passed through 50 ten thousand sheets at a speed of 70 sheets per minute in the lateral direction. Then, evaluation was performed according to the following criteria. Here, the comparison of the electric power reduction ratio in the present evaluation is based on comparative example 1 for example 1. For example 2, reference is made to comparative example 2. For example 3, reference is made to comparative example 3. For example 4, reference is made to comparative example 4. For example 5, reference is made to comparative example 5. In addition, comparative example 7 was based on comparative example 1. Therefore, in the items of the energy saving performance evaluation in table 1, comparative examples 1 to 5 are described as "-". In comparative example 6, the energy saving performance was not evaluated. Therefore, in the item of the energy saving performance evaluation in table 1, comparative example 6 is also described as "-".

Further, as for the electric power, the electric power to energize the heater in order to maintain the temperature of the paper passing portion surface of the fixing film at 170 ℃ was measured.

Class a: the electric power reduction ratio is 5% or more compared with the fixing device of the comparative example in which the mold release layer is made of the same PFA type and thickness;

class B: the electric power reduction ratio is 1% or more and less than 5% as compared with the fixing device of comparative example in which the mold release layer is made of the same PFA type and thickness;

next, examples and comparative examples will be specifically described.

Example 1

(substrate)

SUS having an inner diameter of 24mm and a thickness of 30 μm was used as a substrate.

(formation of inner sliding layer)

First, an equimolar amount of an aromatic tetracarboxylic dianhydride or a derivative thereof (3, 3', 4' -biphenyl tetracarboxylic dianhydride) and an aromatic diamine (p-phenylenediamine) are reacted in an aprotic polar organic solvent (N-methyl-2-pyrrolidone) to obtain a polyimide precursor solution. The polyimide precursor solution obtained was applied to the inner peripheral surface of a substrate by a ring coating method, heated to 150 ℃ by an electric furnace, dried, heated at 200 ℃ for 30 minutes, and further heated at 350 ℃ for 30 minutes, to imidize the polyimide precursor, thereby forming an inner sliding layer. The thickness of the inner sliding layer was set to 12. Mu.m.

(formation of primer layer and elastic layer)

For the substrate on which the inner sliding layer was formed, the primer layer and the elastic layer were formed as follows.

A hydrosilyl-based silicone primer (DY 39-051A/B (trade name); manufactured by Dow Toray Co., ltd.) was applied to the substrate, and the substrate was heat-cured at 200℃for 5 minutes. An addition reaction type liquid silicone rubber (DY 35-1310A/B) containing alumina as a heat conductive filler was coated on the primer layer, and heat curing was performed at 200 ℃ for 30 minutes to form a silicone rubber elastic layer.

The elastic layer 22 had a thermal conductivity of 1.0W/mK and a thickness of 250. Mu.m.

(application of adhesive layer)

After the elastic layer was formed, an adhesive (SE 1819CV A/B (trade name); dow Toray Co., ltd.) was applied to the elastic layer by a ring coating method at a thickness of 7. Mu.m.

(formation of release layer)

After the adhesive is applied, the PFA tube as the release layer is vacuum-expanded from the outside and covered with the adhesive by a method (vacuum-expanded covering method). Specifically, the PFA tube is sucked in a vacuum state to expand the diameter of the inner surface of the outer tube having an inner diameter larger than the outer diameter of the work after the elastic layer coated with the adhesive is formed, and the work is inserted therein and then the vacuum is released, thereby coating the adhesive. Excess adhesive and air between the PFA tube and the elastic layer are exhausted by an O-ring, and then heated by an electric furnace to cure/bond the adhesive. Then, both end portions are cut to a desired length, thereby obtaining a fixing film.

The release layer of the fixing film was a PFA tube having a thickness of 20 μm and an inner diameter of 23.0mm, which was produced by extrusion molding of PFA (trade name: neoflon PFA AP-231SH;Daikin Industries,Ltd) as a raw material from a cylindrical die. The length L of the tube in the longitudinal direction was 400mm. The average value of the X values measured at each position every 10mm from one end portion toward the other end portion in the longitudinal direction of the tube was 34.9. Further, with respect to the fixing film to which the tube was attached, the average value of the X values of the release layer (before heat treatment) measured at positions every 10mm from one end portion toward the other end portion in the longitudinal direction of the fixing film was 38.4. The reason why the value of X is larger than that of X in the case of a tube is considered to be that: by expanding the diameter of the tube and covering the adhesive layer, the crystalline state of the tube (release layer) becomes higher.

(Heat treatment of release layer)

The fixing film coated with the PFA tube as a release layer is inserted into a heating cylinder having an inner diameter larger than an outer diameter thereof, and the fixing film is heated. At this time, only the central region of the fixing film, whose length in the direction of the rotation axis is 0.70L, where the length in the direction of the rotation axis is L, was subjected to heat treatment by the belt heater inside the heating cylinder corresponding to the length. The heating control temperature was set to 320℃so that the solid temperature of the release layer was equal to or higher than the melting temperature (305 ℃) of PFA.

On the other hand, both end regions of the fixing film are heated and controlled at a temperature of 150 ℃ which does not exceed the melting temperature of PFA.

The heating time was set to a time period in which the solid temperature of the release layer could sufficiently reach the predetermined temperature, and was set to 3 minutes after the fixing film was put into the heating cylinder. After 3 minutes of charging, the fixing film was taken out of the heating cylinder to room temperature atmosphere, and the release layer was cooled to crystallize.

The release layer is separated from the fixing film subjected to the heat treatment. Specifically, the surface layer was peeled off from the base material together with the elastic layer, and the elastic layer adhered to the surface layer was dissolved using a silicone dissolving agent (trade name: e Solv 21RS;KANEKO CHEMICAL CO, ltd. Product), whereby only the release layer having a ring shape was taken out.

Using the obtained release layer, x=ic/Ia was measured by the aforementioned reflection X-ray diffraction method for a surface corresponding to the outer surface of the fixing film. Specifically, X at positions every 10mm was measured for an end region of the release layer from the end of the release layer on both sides in the direction perpendicular to the circumferential direction (direction along the axis) to a length of 0.15L, and the average value Xe was calculated. In addition, for the central region located between the end regions, X at positions every 10mm was measured from one end toward the other end, and the average value Xm thereof was calculated. The values of Xe, xm and Xe/Xm are set forth in Table 1.

Example 2

The same raw material as that of the PFA tube of example 1 was used to prepare a PFA tube having a thickness of 15. Mu.m. The average value of the values of X measured at each position every 10mm from one end portion toward the other end portion in the longitudinal direction of the tube was 38.4. A fixing film and a release layer thereof were obtained in the same manner as in example 1, except that the PFA tube was used. The average value of the X values of the release layer before heat treatment was 41.6.

Example 3

The same raw material as that of the PFA tube of example 1 was used to prepare a PFA tube having a thickness of 25. Mu.m. The average value of the values of X measured at each position every 10mm from one end portion toward the other end portion in the longitudinal direction of the tube was 31.7. A fixing film and a release layer thereof were obtained in the same manner as in example 1, except that the PFA tube was used. The average value of the X values of the release layer before heat treatment was 37.5.

Example 4

PFA (trade name: teflon PFA959HPplus; manufactured by Chemours-Mitsui Co.) as a raw material was extruded from a cylindrical die to prepare a PFA tube having a thickness of 20 μm and an inner diameter of 23.0 mm. The length L of the tube in the direction perpendicular to the circumferential direction was 400mm. The average value of the X values measured at each position every 10mm from one end portion toward the other end portion in the longitudinal direction of the tube was 58.7.

A fixing film and a release layer thereof were obtained in the same manner as in example 1, except that the PFA tube was used. The average value of the X values of the release layer before heat treatment was 60.5.

Example 5

The same raw material as that of the PFA tube of example 4 was used to prepare a PFA tube having a thickness of 40. Mu.m. The average value of the X values measured at each position every 10mm from one end portion toward the other end portion in the longitudinal direction of the PFA tube was 41.1. A fixing film and a release layer thereof were obtained in the same manner as in example 4, except that the PFA tube was used. The average value of the X values of the release layer before heat treatment was 44.1.

Comparative example 1

A fixing film was produced in the same manner as in example 1, except that the heat treatment was not performed. The values of Xe and Xm of the release layer were obtained by the same reflection X-ray diffraction method as in example. Further, xe/Xm was calculated from these values.

Comparative example 2

A fixing film was produced in the same manner as in example 2, except that the heat treatment was not performed. The values of Xe and Xm of the release layer were obtained by the same reflection X-ray diffraction method as in example. Further, xe/Xm was calculated from these values.

Comparative example 3

A fixing film was produced in the same manner as in example 3, except that the heat treatment was not performed. The values of Xe and Xm of the release layer were obtained by the same reflection X-ray diffraction method as in example. Further, xe/Xm was calculated from these values.

Comparative example 4

A fixing film was produced in the same manner as in example 4, except that the heat treatment was not performed. The values of Xe and Xm of the release layer were obtained by the same reflection X-ray diffraction method as in example. Further, xe/Xm was calculated from these values.

Comparative example 5

A fixing film was produced in the same manner as in example 5, except that the heat treatment was not performed. The values of Xe and Xm of the release layer were obtained by the same reflection X-ray diffraction method as in example. Further, xe/Xm was calculated from these values.

Comparative example 6

Except "Algoflon PFA: f1520 A PFA tube having a thickness of 20 μm was prepared in the same manner as in example 1 except that "PFA" was used. The average value of the values of X measured at each position every 10mm from one end portion toward the other end portion in the longitudinal direction of the tube was 53.5.

Then, a fixing film was obtained in the same manner as in example 1, except that the PFA tube was used and heat treatment was not performed. The values of Xe and Xm of the release layer were obtained by the same reflection X-ray diffraction method as in example. Further, xe/Xm was calculated from these values.

Comparative example 7

A fixing film was produced in the same manner as in example 1, except that the heat treatment of the release layer was performed as described below. The release layer separated from the obtained fixing film was subjected to the same reflection X-ray diffraction method as in example to obtain Xe and Xm values. Further, xe/Xm was calculated from these values.

< Heat treatment >

The cartridge heater used in example 1 was used. Wherein, regarding the heating control temperature, heating is performed at 320 ℃ higher than the melting temperature of PFA for 3 minutes in the entire region along the direction of the rotation axis of the fixing film. After heating, the fixing film was taken out from the heating cylinder and placed under an atmosphere of normal temperature to crystallize the PFA of the release layer.

TABLE 1

As shown in examples 1 to 5, according to the fixing film of one embodiment of the present disclosure, the following fixing film can be obtained in a state in which the average value Xe of X of the release layer in the end region is 1.20 times or more the average value Xm of X in the central region: the abrasion of the end area where the edge of the paper is abutted can be prevented, the energy saving performance is good, and the cracking of the release layer in the central area along the axial direction can be prevented even if the release layer is used for a long time.

The energy saving property of the fixing film of comparative example 7 is better than that of the fixing film of comparative example 1. However, in the entire region in the direction along the rotation axis of the fixing film, X is smaller than that of the fixing belt of comparative example 1. Therefore, abrasion due to contact of the end portions of the paper occurs in the end portions, and sufficient durability cannot be maintained.

In addition, since the fixing films of comparative examples 4 and 6 have large values of Xe and Xm, that is, have large in-plane orientation of crystals, cracking of the release layer occurs during use durability.

The embodiments of the present disclosure have been described above, but the present disclosure is not limited to the above embodiments.

The present invention has been described with reference to the exemplary embodiments, but it should be understood that the present invention is not limited to the above-described exemplary embodiments. The scope of the claims should be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A fixing film having a ring shape, comprising at least a base material, an elastic layer and a release layer in this order,

the release layer is constituted of a tube containing a fluororesin,

the ratio Ic/Ia of the maximum X-ray diffraction intensity Ic of 2 theta=17 to 19 DEG relative to the maximum X-ray diffraction intensity Ia of 2 theta=39.5 to 40.5 DEG of the release layer by the reflection X-ray diffraction method is set as X,

The length of the fixing film along the direction of the rotation axis is L,

The average value of X in the end region of the fixing film from the two ends to 0.15L along the direction of the rotation axis is Xe,

When the average value of the X in the central region having a length of 0.70L in the direction of the rotation axis, which is present between the 2 end regions, is set to Xm,

the Xe/Xm ratio of Xe to Xm is 1.20 or more.

2. The fixing film according to claim 1, wherein the Xe/Xm is 1.20 to 5.00.

3. The fixing film according to claim 1, wherein the Xe/Xm is 1.23 to 4.20.

4. The fixing film according to claim 1, wherein the Xe/Xm is 1.25 to 2.00.

5. The fixing film according to claim 1, wherein the Xe is 35.0 to 62.0.

6. The fixing film according to claim 1, wherein the Xe is 37.0 to 50.0.

7. The fixing film according to claim 1, wherein the Xe is 37.0 or more and less than 50.0.

8. The fixing film according to claim 1, wherein Xm is 10.0 to 35.0.

9. The fixing film according to claim 1, wherein the tube is a cylindrical extrusion.

10. The fixing film according to claim 1, wherein the fluororesin is a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.

11. The fixing film according to claim 1, wherein the tube containing a fluororesin is a cylindrical extrusion molded article of a resin mixture containing a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.

12. The fixing film according to claim 1, wherein the thickness of the release layer is 10 to 45 μm.

13. A heat fixing device having the fixing film according to any one of claims 1 to 12.

14. The heat fixing device according to claim 13, wherein the heat fixing device further comprises a heater disposed so as to contact an inner peripheral surface of the fixing film.

15. The heat fixing device according to claim 14, further comprising a pressure roller that is pressed against the fixing film with the heater interposed therebetween.

16. An electrophotographic image forming apparatus provided with the heat fixing device according to any one of claims 13 to 15.

17. A method for producing a fixing film according to any one of claims 1 to 12, comprising the steps of:

18. The method for producing a fixing film according to claim 17, wherein the fluororesin is a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer.

19. The method for producing a fixing film according to claim 18, wherein the region corresponding to the central region is heat-treated at a temperature ranging from 280 to 400 ℃.

20. The method for producing a fixing film according to claim 18 or 19, wherein the region corresponding to the end region is heat-treated at a temperature in the range of 100 to 250 ℃.