Fixing Belt, Fixing Device, and Image Forming Apparatus

Abstract

The present application relates to a fixing belt, a fixing device, and an image forming apparatus. The fixing belt comprises: an annular polyimide resin base layer having an imidization ratio at its outer peripheral surface lower than that at its center portion in the thickness direction; a metal layer provided on the outer peripheral surface of the polyimide resin base layer; and an elastic layer provided on the outer peripheral surface of the metal layer.

Description

Technical Field

[0001] The present invention relates to a fixing belt, a fixing device, and an image forming apparatus. Background Art

[0002] In an image forming apparatus (copier, facsimile machine, printer, etc.) using electrophotography, a toner image formed on a recording material is fixed by a fixing device including a fixing belt to form an image.

[0003] For example, WO2011 / 013221 discloses “a fixing belt comprising a cylindrical metal base and a polyimide resin layer formed on the inner peripheral surface of the cylindrical base, wherein the imidization rate of the polyimide resin layer is 70 to 93%”.

[0004] Japanese Patent Application Laid-Open No. 2005-121975 discloses “a fixing belt having a belt substrate including a laminated polyimide resin layer and a metal layer, wherein the imidization rate of the polyimide forming the polyimide resin layer is 95% or more”.

[0005] In addition, Japanese Patent Publication No. 2004-012669 discloses "an electromagnetic induction heat-releasing fixing belt, comprising a polyimide resin layer, a metal layer formed on the surface thereof and dissipating heat by electromagnetic induction, and a release layer formed on the outermost peripheral surface, wherein the polyimide resin layer contains an imide compound obtained by imidizing polyamic acid in the presence of a dehydrating cyclizing agent, and the imidization ratio of the imide compound is 95 to 100%."

[0006] In addition, Japanese Patent Application Laid-Open No. 2013-61565 discloses an endless belt comprising at least one metal layer and an anti-sticking layer provided on the metal layer, wherein the stress of the metal material used in the metal layer before reaching the upper yield point in the stress-strain diagram is 343 N / mm 2 The stress-strain diagram described above was measured as follows: The metal material test piece was measured in accordance with JIS Z2241, "Tension Test of Metal Materials," using the metal material test piece as specified in JIS Z2201, "Tension Test Specimens for Metal Materials," and the tensile test was conducted using the testing machine specified in JIS B7721, "Tension / Compression Testing Machines - Calibration / Verification Methods for Force Measurement Systems."

[0007] In addition, Japanese Patent Gazette No. 2004-70191 discloses "a belt which is an endless belt having a base layer formed of a synthetic resin, a metal layer stacked thereon, and a covering layer formed of a synthetic resin stacked thereon, wherein the above-mentioned metal layer is formed near a neutral axis that does not cause strain when the belt is bent and deformed." Summary of the Invention

[0008] Technical problem to be solved by the invention

[0009] The technical problem to be solved by the present invention is to provide a fixing belt. Compared with a fixing belt having an annular polyimide resin base layer, a metal layer provided on the outer peripheral surface of the polyimide resin base layer, and an elastic layer provided on the outer peripheral surface of the metal layer, in which the imidization rates of the central portion in the thickness direction and the outer peripheral surface of the polyimide resin base layer are the same, the fixing belt of the present invention can suppress the peeling of the polyimide resin base layer and the metal layer after storage in a high temperature and high humidity environment.

[0010] Means used to solve problems

[0011] According to a first aspect of the present invention, there is provided a fixing belt comprising: an annular polyimide resin base material layer having an imidization rate at its outer peripheral surface lower than that at its central portion in the thickness direction; a metal layer provided on the outer peripheral surface of the polyimide resin base material layer; and an elastic layer provided on the outer peripheral surface of the metal layer.

[0012] According to the second aspect of the present invention, the imidization rate of the outer peripheral surface of the polyimide resin base material layer is 50% or more and 95% or less.

[0013] According to a third aspect of the present invention, the imidization rate of the outer peripheral surface of the polyimide resin base material layer is 60% or more and 90% or less.

[0014] According to a fourth aspect of the present invention, the imidization rate of the outer peripheral surface of the polyimide resin base material layer is 60% or more and 80% or less.

[0015] According to a fifth aspect of the present invention, an absolute value of a difference in imidization rate between the central portion in the thickness direction and the outer peripheral surface of the polyimide resin base material layer is 5% or more and 50% or less.

[0016] According to a sixth aspect of the present invention, an absolute value of a difference in imidization rate between the central portion in the thickness direction and the outer peripheral surface of the polyimide resin base material layer is 10% to 40%.

[0017] According to a seventh aspect of the present invention, an absolute value of a difference in imidization rate between the central portion in the thickness direction and the outer peripheral surface of the polyimide resin base material layer is 20% or more and 40% or less.

[0018] According to an eighth aspect of the present invention, the polyimide resin base material layer is a base material layer containing an aromatic polyimide resin.

[0019] According to a ninth aspect of the present invention, the aromatic polyimide resin is a polyimide resin having a structural unit represented by the following general formula (PI1).

[0020] (PI1)

[0021]

[0022] (In the general formula, R P1 represents phenyl or biphenyl, R P2 represents a divalent aromatic group.)

[0023] According to the tenth embodiment of the present invention, the metal layer comprises: a base metal layer provided on the outer peripheral surface of the polyimide resin substrate layer; a metal heat dissipation layer provided on the outer peripheral surface of the base metal layer; and a metal protective layer provided on the outer peripheral surface of the metal heat dissipation layer.

[0024] According to an eleventh aspect of the present invention, there is provided a fixing device comprising:

[0025] The fixing belt; a pressure member for pressurizing the outer peripheral surface of the fixing belt; and an electromagnetic induction device for causing at least a portion of the metal layer of the fixing belt to release heat through electromagnetic induction. A recording medium having an unfixed toner image formed on its surface is clamped between the fixing belt and the pressure member to fix the toner image to the recording medium.

[0026] According to the 12th embodiment of the present invention, there is provided an image forming device comprising: an image retainer; a charging device for charging the surface of the image retainer; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the image retainer; a developing device for developing the electrostatic latent image formed on the surface of the image retainer using a toner to form a toner image; a transfer device for transferring the toner image formed on the surface of the image retainer to a recording medium; and the fixing device for fixing the toner image to the recording medium.

[0027] Effects of the Invention

[0028] According to the above-mentioned scheme 1, 8, 9 or 10, a fixing belt is provided. Compared with a case where the imidization ratios of the central portion in the thickness direction and the outer peripheral surface of the polyimide resin base layer are the same in a fixing belt having an annular polyimide resin base layer, a metal layer provided on the outer peripheral surface of the polyimide resin base layer, and an elastic layer provided on the outer peripheral surface of the metal layer, the fixing belt of this scheme can suppress the peeling of the polyimide resin base layer and the metal layer after storage in a high temperature and high humidity environment.

[0029] According to the second embodiment, a fixing belt is provided that can suppress peeling between the polyimide resin base material layer and the metal layer after storage in a high-temperature and high-humidity environment, compared to a case where the imidization rate of the outer peripheral surface of the polyimide resin base material layer is less than 50% or greater than 95%.

[0030] According to the third or fourth aspect, there is provided a fixing belt capable of suppressing cracking of the metal layer compared to a case where the imidization rate of the outer peripheral surface of the polyimide resin base layer is less than 60% or greater than 90%.

[0031] According to the fifth embodiment, a fixing belt is provided, which can suppress the peeling of the polyimide resin base material layer and the metal layer after storage in a high temperature and high humidity environment, compared with the case where the absolute value of the difference in the imidization rate between the central part in the thickness direction and the outer peripheral surface of the polyimide resin base material layer is less than 5% or greater than 50%.

[0032] According to the sixth or seventh embodiment, a fixing belt is provided, which can suppress cracking of the metal layer compared to a case where the absolute value of the difference in imidization rate between the central portion in the thickness direction and the outer peripheral surface of the polyimide resin base material layer is less than 10% or greater than 40%.

[0033] According to the above-mentioned scheme 11 or 12, a fixing device having the following fixing belt or an image forming device having the fixing device is provided. Compared with a fixing belt having an annular polyimide resin base material layer, a metal layer provided on the outer peripheral surface of the polyimide resin base material layer, and an elastic layer provided on the outer peripheral surface of the metal layer, and the imidization ratio of the central part and the outer peripheral surface of the polyimide resin base material layer in the thickness direction of the fixing belt is the same, the fixing belt provided by this scheme can suppress the peeling of the polyimide resin base material layer and the metal layer after storage in a high temperature and high humidity environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic cross-sectional view showing a layer structure in an example of the fixing belt according to the present embodiment.

[0035] Figure 2 This is a schematic structural diagram showing an example of the fixing device according to the present embodiment.

[0036] Figure 3 This is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION

[0037] Hereinafter, an embodiment as an example of the present invention will be described.

[0038] [Fusing belt]

[0039] The fixing belt of this embodiment includes: an annular polyimide resin base layer having an imidization rate lower on its outer peripheral surface than on its center portion in the thickness direction; a metal layer provided on the outer peripheral surface of the polyimide resin base layer; and an elastic layer provided on the outer peripheral surface of the metal layer.

[0040] The fixing belt of this embodiment, with the above-described configuration, can suppress separation between the polyimide resin base material layer and the metal layer after storage in a high-temperature, high-humidity environment (eg, 40° C., 80% RH). The reason for this is presumably as follows.

[0041] In the polyimide resin substrate layer, due to the imidization of the polyimide resin, the surface is in a state with few polar groups (amide groups, carboxyl groups). Therefore, the polyimide resin substrate layer has low adhesion to the metal layer due to reasons such as low wettability with the plating solution and small interaction (hydrogen bonding, etc.) with the metal layer caused by the polar groups. In particular, under high temperature and high humidity environments, since the moisture absorbed by the polyimide resin layer does not pass through the metal layer, the adhesion between the polyimide resin substrate layer and the metal layer is reduced.

[0042] In contrast, if the imidization rate of the peripheral surface in the polyimide resin base material layer is lower than the imidization rate of the thickness direction center portion, the polar groups (amide groups, carboxyl groups) of the peripheral surface are increased than the thickness direction center portion. Therefore, in the peripheral surface of the polyimide resin base material layer, the wettability with the plating solution increases, and the interaction (hydrogen bond, etc.) with the metal layer produced by the polar groups also plays a role. As a result, even under high temperature and high humidity environment, the adhesion of the polyimide resin base material layer to the metal layer also increases.

[0043] From the above, it is inferred that the separation between the polyimide resin base material layer and the metal layer after storage in a high-temperature and high-humidity environment can be suppressed.

[0044] Hereinafter, the fixing belt according to the present embodiment will be described in detail with reference to the drawings.

[0045] Figure 1 1 is a schematic structural diagram showing an example of a fixing belt.

[0046] Figure 1 The fixing belt 10 shown has a layer structure in which a metal layer 10B, an adhesive layer 10C, an elastic layer 10D, and a release layer 10E are sequentially laminated on the outer peripheral surface of an annular polyimide resin base layer 10A. The adhesive layer 10C and the release layer 10E are provided as needed.

[0047] The metal layer 10B is formed by, for example, sequentially stacking a base metal layer 102, a metal heat dissipation layer 104, and a metal protective layer 106. The base metal layer 102 is provided as needed. Furthermore, when the fixing belt 10 is used in an electromagnetic induction fixing device, the metal heat dissipation layer 104 is a layer that dissipates heat by electromagnetic induction.

[0048] It should be noted that the fixing belt 10 of this embodiment is not limited to the above-mentioned structure, and may further include other layers. It should be noted that in the following description, the reference numerals of each layer may be omitted.

[0049] <Polyimide Resin Base Material Layer 10A>

[0050] The polyimide resin substrate layer 10A (hereinafter referred to as "substrate layer 10A") contains a polyimide resin as its main component. It should be noted that the terms "mainly" and "main component" refer to a mass ratio of 50% or more, and are used interchangeably herein. In addition to the polyimide resin, the substrate layer 10A may also contain known additives.

[0051] The content of the polyimide resin relative to the entire base material layer 10A is, for example, 50 mass % or more, preferably 60 mass % or more, more preferably 70 mass % or more, further preferably 78 mass % or more, and particularly preferably 90 mass % or more.

[0052] In the substrate layer 10A, the imidization ratio on the outer peripheral surface is lower than that in the center portion in the thickness direction. Furthermore, to prevent separation between the substrate layer 10A and the metal layer 10B (in this embodiment, the base metal layer 102) after storage in a high-temperature, high-humidity environment, the imidization ratio on the outer peripheral surface of the substrate layer 10A is preferably 50% or more and 95% or less.

[0053] From the same viewpoint, the absolute value of the difference in imidization rate between the center portion in the thickness direction and the outer peripheral surface of the base material layer 10A is preferably 5% or more and 50% or less.

[0054] When the imidization rate of the outer peripheral surface of the substrate layer 10A is within an appropriate range, the bonding strength between the substrate layer 10A and the metal layer 10B is increased due to the action of the polar groups (amide groups, carboxyl groups) generated by the decomposition of the imide bonds. On the other hand, if the imidization rate of the outer peripheral surface of the substrate layer 10A is too low, the cohesive failure strength of the outer peripheral surface of the substrate layer 10A may be reduced due to excessive decomposition of the imide bonds, thereby reducing the bonding strength between the substrate layer 10A and the metal layer 10B. In addition, due to the action of excessively generated polar groups, the hydrophilicity of the outer peripheral surface of the substrate layer 10A increases, thereby causing water to reside at the bonding interface between the substrate layer 10A and the metal layer 10B, which may reduce the bonding strength between the substrate layer 10A and the metal layer 10B.

[0055] Therefore, the imidization rate of the outer peripheral surface of the base layer 10A is preferably within the above range. In addition, the absolute value of the difference in imidization rate between the center portion in the thickness direction and the outer peripheral surface of the base layer 10A is also preferably within the above range.

[0056] Here, the fixing belt 10 is rotated while being pressurized by, for example, a pressure member within the fixing device, thereby applying stress and repeatedly bending. In particular, to facilitate the release of recording media from the fixing belt 10, the fixing belt 10 moves along the outer surface of the pressure member in the area of contact with the pressure member, causing the curvature to fluctuate periodically. In this case, the repeated bending increases the load on the metal layer.

[0057] Furthermore, if the fixing belt 10 is used for a long period of time within the fixing device of an image forming apparatus, repeated flexing may cause breakage (hereinafter also referred to as "cracks") in the metal layer 10B (particularly the metal heat dissipation layer 104). In particular, if the adhesion between the base layer 10A and the metal layer 10B is low, rapid heating under high temperature and high humidity conditions, while containing moisture, can cause separation between the base layer 10A and the metal layer 10B, which can easily lead to cracks in the metal layer 10B.

[0058] Therefore, from the viewpoint of suppressing cracks in the metal layer 10B, the imidization rate of the outer peripheral surface of the base layer 10A is preferably 60% to 90%, and more preferably 60% to 80%.

[0059] From the same viewpoint, the difference (absolute value) in imidization rate between the center portion in the thickness direction and the outer peripheral surface of the base layer 10A is preferably 10% to 40%, more preferably 20% to 40%.

[0060] As a method for making the imidization rate of the peripheral surface of the substrate layer 10A lower than that of the central part in the thickness direction or within the above-mentioned range, the following methods can be cited: 1) a method of treating the peripheral surface of the substrate layer 10A with an alkaline solution; 2) a method of subjecting the peripheral surface of the substrate layer 10A to electron beam (ultraviolet rays, etc.) treatment, excimer laser treatment, plasma treatment; and the like.

[0061] The imidization ratios of the central portion in the thickness direction and the outer peripheral surface of the base material layer 10A are measured as follows.

[0062] (i) The infrared absorption spectrum of the outer peripheral surface of the polyimide resin substrate layer after surface modification was measured using a Fourier transform infrared spectrophotometer (Frontier, manufactured by Perkin Elmer). In order to obtain an infrared spectrum near the surface, the ATR method (Universal ATR / Ge Crystal) was used for measurement. The 1714 cm -1 The peaks assigned to the imide bond (Ab(1714cm -1 ))'s absorbance relative to 1500 cm -1 The peaks attributed to aromatic rings (Ab(1514cm -1 On the other hand, the center portion in the thickness direction of the polyimide resin base material layer was mechanically cut to expose the inner surface for measurement.

[0063] (ii) Similarly, a standard sample with an imidization rate of 100% was heated at 380°C for 60 minutes to obtain the wavelength of 1714 cm -1 The peaks assigned to the imide bond (Ab(1714cm -1 ))'s absorbance relative to 1500 cm -1 The peaks attributed to aromatic rings (Ab(1514cm -1 ))'s absorbance ratio I'(100).

[0064] Then, the imidization ratio of the outer peripheral surface of the polyimide substrate was calculated based on the following formula using the measured imide bond ratios I'(100) and I(x).

[0065] Formula: Imidization ratio of the outer peripheral surface of the polyimide resin base material layer = I(x) / I'(100)

[0066] Formula: I'(100)=(Ab'(1714cm -1 )) / (Ab'(1514cm -1 ))

[0067] Formula: I(x)=(Ab(1714cm -1 )) / (Ab(1514cm -1 ))

[0068] It should be noted that this imidization rate measurement is applicable to the measurement of the imidization rate of aromatic polyimides. When measuring the imidization rate of aliphatic polyimides, a peak derived from a structure that does not change before and after the imidization reaction is used as the internal standard peak instead of the absorption peak of the aromatic ring.

[0069] Examples of the polyimide resin include imides of polyamic acid (a precursor of the polyimide resin), which is a polymer of tetracarboxylic dianhydride and a diamine compound. Specifically, examples of the polyimide resin include resins obtained by imidizing a polyamic acid solution obtained by polymerizing equimolar amounts of tetracarboxylic dianhydride and a diamine compound in a solvent.

[0070] Examples of the tetracarboxylic dianhydride include aromatic and aliphatic compounds. From the viewpoint of heat resistance, an aromatic compound may be used.

[0071] Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 3,3',4,4'-biphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3',4,4'-biphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3',4,4'-tetraphenylsilane tetracarboxylic dianhydride, 1,2,3,4-furan tetracarboxylic dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride, 4,4'-bis( 3,4-dicarboxyphenoxy)diphenylsulfone dianhydride, 4,4'-bis(3,4-dicarboxyphenoxy)diphenylpropane dianhydride, 3,3',4,4'-perfluoroisopropylidene diphthalic anhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, bis(phthalic acid)phenylphosphine oxide dianhydride, p-phenylene-bis(triphenylphthalic acid) dianhydride, m-phenylene-bis(triphenylphthalic acid) dianhydride, bis(triphenylphthalic acid)-4,4'-diphenyl ether dianhydride, bis(triphenylphthalic acid)-4,4'-diphenylmethane dianhydride, etc.

[0072] Examples of the aliphatic tetracarboxylic dianhydride include butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,3-dimethyl-1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4-cyclopentanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentyl acetic dianhydride, 3,5,6-tricarboxynorbornane-2-acetic dianhydride, 2,3,4,5-tetrahydrofurantetracarboxylic dianhydride, 5-(2,5-dioxotetrahydrofuranyl)-3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, and bicyclo[2,2,2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride. aliphatic or alicyclic tetracarboxylic dianhydrides such as 1,3,3a,4,5,9b-hexahydro-(2,5-dioxo-3-furyl)-naphthol[1,2-c]furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-5-methyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphthol[1,2-c]furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxo-3-furyl)-naphthol[1,2-c]furan-1,3-dione, etc.

[0073] Among these, the tetracarboxylic dianhydride is preferably an aromatic tetracarboxylic dianhydride. Specifically, for example, pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-biphenyl ether tetracarboxylic dianhydride, and 3,3',4,4'-benzophenonetetracarboxylic dianhydride are preferred. Further preferred are pyromellitic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 3,3',4,4'-benzophenonetetracarboxylic dianhydride. Particularly preferred is 3,3',4,4'-biphenyltetracarboxylic dianhydride.

[0074] In addition, the tetracarboxylic dianhydride may be used individually by 1 type, and may use 2 or more types together in combination.

[0075] When two or more types are used in combination, either aromatic tetracarboxylic dianhydride or aliphatic tetracarboxylic dianhydride may be used in combination, or aromatic tetracarboxylic dianhydride and aliphatic tetracarboxylic dianhydride may be used in combination.

[0076] On the other hand, a diamine compound is a diamine compound having two amino groups in its molecular structure. Examples of the diamine compound include aromatic and aliphatic compounds, and aromatic compounds are preferred.

[0077] Examples of the diamine compound include p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylethane, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4'-diaminobiphenyl, 5-amino-1-(4'-aminophenyl)-1,3,3-trimethylindane, 6-amino-1-(4'-aminophenyl)-1,3,3-trimethylindane, 4,4'-diaminobenzanilide, 3,5-diaminobenzanilide, and 4,4'-diaminobenzanilide. -Diamino-3'-trifluoromethylbenzanilide, 3,5-diamino-4'-trifluoromethylbenzanilide, 3,4'-diaminodiphenyl ether, 2,7-diaminofluorene, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-methylene-bis(2-chloroaniline), 2,2',5,5'-tetrachloro-4,4'-diaminobiphenyl, 2,2'-dichloro-4,4'-diamino-5,5'-dimethoxybiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 4,4'-diamino-2,2'-bis(trifluoromethyl)biphenyl , 2,2-bis[4-(4-aminophenoxy)phenyl]propane, 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane, 1,4-bis(4-aminophenoxy)benzene, 4,4'-bis(4-aminophenoxy)-biphenyl, 1,3'-bis(4-aminophenoxy)benzene, 9,9-bis(4-aminophenyl)fluorene, 4,4'-(p-phenylene diisopropylidene)dianiline, 4,4'-(m-phenylene isopropylidene)dianiline, 2,2'-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane, 4,4'-bis Aromatic diamines such as [4-(4-amino-2-trifluoromethyl)phenoxy]-octafluorobiphenyl; aromatic diamines having two amino groups bonded to an aromatic ring and a heteroatom other than the nitrogen atom of the amino groups such as diaminotetraphenylthiophene; 1,1-m-phenylenediamine, 1,3-propylenediamine, tetramethylenediamine, pentamethylenediamine, 1,8-octanediamine, 1,9-nonanediamine, 4,4-diaminoheptamethylenediamine, 1,4-cyclohexanediamine, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7-indanylenedimethylenediamine, tricyclo[6,2,1,0 2.7 ]-undecenedimethyldiamine, 4,4'-methylenebis(cyclohexylamine) and other aliphatic diamines and alicyclic diamines.

[0078] Among these, the diamine compound is preferably an aromatic diamine compound. Specific examples thereof include p-phenylenediamine, m-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfide, and 4,4'-diaminodiphenyl sulfone. 4,4'-diaminodiphenyl ether and p-phenylenediamine are particularly preferred.

[0079] It should be noted that the diamine compound may be used alone or in combination of two or more. In addition, when two or more are used in combination, either an aromatic diamine compound or an aliphatic diamine compound may be used individually, or an aromatic diamine compound and an aliphatic diamine compound may be used in combination.

[0080] Among these, aromatic polyimide resins (specifically, imides of polyamic acid (a precursor of polyimide resins) which are polymers of aromatic tetracarboxylic dianhydride and aromatic diamine compounds) are preferred as polyimide resins from the perspective of heat resistance. Specifically, the base layer 10A is preferably a base layer containing an aromatic polyimide resin.

[0081] Furthermore, as the aromatic polyimide resin, a polyimide resin having a structural unit represented by the following general formula (PI1) is more preferable.

[0082] [Chemistry 2]

[0083] (PI1)

[0084]

[0085] In the general formula, R P1 represents phenyl or biphenyl, R P2 represents a divalent aromatic group.

[0086] R P2 Examples of the divalent aromatic group include phenylene, naphthyl, biphenyl, and diphenyl ether. As the divalent aromatic group, phenylene and biphenyl are preferred from the viewpoint of heat resistance.

[0087] The number average molecular weight of the polyimide resin may be 5,000 to 100,000, more preferably 7,000 to 50,000, and even more preferably 10,000 to 30,000.

[0088] The number average molecular weight of the polyimide resin can be measured by gel permeation chromatography (GPC) under the following measurement conditions.

[0089] Column: Tosoh TSKgel α-M (7.8mm ID×30cm)

[0090] Eluent: DMF (dimethylformamide) / 30mM LiBr / 60mM phosphoric acid

[0091] Flow rate: 0.6 mL / min

[0092] Injection volume: 60 μL

[0093] Detector: RI (differential refractive index detector)

[0094] The base material layer 10A may contain known additives such as a conductive agent, a filler, and a lubricant in addition to the polyimide resin.

[0095] The thickness of the base material layer 10A is, for example, preferably from 20 μm to 200 μm, more preferably from 30 μm to 150 μm, and still more preferably from 40 μm to 130 μm.

[0096] It should be noted that the outer peripheral surface of the base layer 10A may be subjected to a surface roughening treatment (roughening treatment) to increase the surface roughness in advance so that metal particles can be easily attached when forming the base metal layer 102. Examples of the roughening treatment include sandblasting using aluminum oxide abrasives, cutting, and shaving with sandpaper.

[0097] <Base Metal Layer 102>

[0098] The base metal layer 102 is a layer preformed on the outer peripheral surface of the base layer 10A to form the metal heat dissipation layer 104 by electrolytic plating and can be provided as needed. Electrolytic plating is preferred for forming the metal heat dissipation layer 104 from a cost perspective. However, direct electrolytic plating is difficult when using a base layer 10A primarily composed of resin. Therefore, providing the base metal layer 102 is preferred for forming the metal heat dissipation layer 104.

[0099] Examples of methods for forming the base metal layer 102 on the outer peripheral surface of the base layer 10A include electroless plating, sputtering, and vapor deposition. From the perspective of ease of film formation, chemical plating (electroless plating) is preferred.

[0100] Examples of the base metal layer 102 include an electroless nickel plating layer and an electroless copper plating layer. It should be noted that "nickel plating layer" refers to a plating layer containing Ni (e.g., a nickel layer, a nickel alloy layer, etc.), and "copper plating layer" refers to a plating layer containing Cu (e.g., a copper layer, a copper alloy layer, etc.).

[0101] The thickness of the base metal layer 102 is preferably in the range of 0.1 μm to 5 μm, and more preferably in the range of 0.3 μm to 3 μm.

[0102] It should be noted that the thickness of each layer constituting the fixing belt 10 is a value measured as follows: a cross-section is made in the circumferential and axial directions of the cylindrical body of the belt, and the cross-section is observed using a scanning electron microscope ("JSM6700F" manufactured by JEOL Ltd.) at an acceleration voltage of 2.0 kV and 5000 times. The film thickness is measured from the obtained observation image, and the obtained value is the thickness of each layer.

[0103] <Metal Heat Dissipation Layer 104>

[0104] The metal heat dissipation layer 104 is a heat dissipation layer having a function of dissipating heat due to eddy current generated in the layer when a magnetic field is applied, and is made of a metal that can generate electromagnetic induction.

[0105] Examples of metals capable of producing electromagnetic induction include single metals such as nickel, iron, copper, gold, silver, aluminum, chromium, tin, and zinc, or alloys containing two or more metals. Considering cost, heat dissipation, and processability, copper, nickel, aluminum, iron, and chromium are suitable, with copper or alloys containing copper as the main component being particularly preferred.

[0106] The metal heat release layer 104 is formed by a known method, for example, by performing an electrolytic plating process.

[0107] Regarding the thickness of the metal heat dissipation layer 104, the optimal thickness varies depending on the metal material. For example, when copper is used in the metal heat dissipation layer 104, from the perspective of effective heat dissipation, the thickness of the metal heat dissipation layer 104 is preferably in the range of 3 μm to 50 μm, more preferably in the range of 3 μm to 30 μm, and even more preferably in the range of 5 μm to 20 μm.

[0108] <Metal Protective Layer 106>

[0109] The metal protective layer 106 is provided in contact with the metal heat dissipation layer 104 to improve the film strength of the metal heat dissipation layer 104 , suppress cracking due to repeated deformation, suppress oxidation degradation due to repeated heating for a long time, and maintain heat dissipation characteristics.

[0110] The metal protective layer 106 is preferably a thin film with high fracture strength, durability, and oxidation resistance, and is preferably an oxidation-resistant metal. Specifically, it can be composed of copper or nickel, for example. In particular, nickel (or a nickel alloy) is preferably included as an oxidation-resistant metal to suppress cracking caused by repeated deformation and oxidative degradation during repeated heating.

[0111] Regarding the thickness of the metal protective layer 106, the optimal thickness varies depending on its material. For example, when nickel is used to form the metal protective layer, it is preferably in the range of 2 μm to 20 μm, more preferably in the range of 2 μm to 15 μm, and even more preferably in the range of 5 μm to 10 μm.

[0112] When the workability of a thin film is also taken into consideration, the metal protective layer 106 is preferably formed by electrolytic plating, and electrolytic nickel plating having high strength is more preferred.

[0113] When forming by electric field plating, a plating solution containing metal ions such as nickel ions is first prepared, and the base layer 10A having the base metal layer 102 and the metal heat dissipation layer 104 is immersed in the plating solution for electrolytic plating to form an electrolytic plated layer of the required thickness.

[0114] <Adhesive Layer 10C>

[0115] In the layer ( Figure 1 Between the metal protective layer 106 (in the middle) and the elastic layer 10D, an adhesive layer 10C may be interposed as needed from the viewpoint of improving the adhesion between the two layers.

[0116] It should be noted that the adhesive layer 10C is typically provided as a thin film layer (e.g., 1 μm or less) from the perspective of thermal conductivity, etc. The thickness of the adhesive layer 10C is preferably 0.1 μm to 1 μm, and more preferably 0.2 μm to 0.5 μm, from the perspective of ease of forming the adhesive layer.

[0117] The adhesive used in the adhesive layer 10C preferably exhibits minimal changes in the physical properties of the adjacent metal layer 10B even during heat dissipation and exhibits excellent heat transfer to the outer peripheral surface. Specific examples include silane coupling adhesives, silicone adhesives, epoxy resin adhesives, and urethane resin adhesives.

[0118] The adhesive layer 10C can be formed by a known method, for example, by applying a coating liquid for forming an adhesive layer onto the metal layer 10B by a coating method. The coating liquid for forming an adhesive layer can be prepared by a known method, for example, by mixing an adhesive with a solvent as needed and stirring to prepare the coating liquid for forming an adhesive layer.

[0119] Specifically, for example, a coating liquid for forming an adhesive layer is first applied (for example, by flow coating (spiral winding coating)) on the metal layer 10B, and dried and heated as needed to form an adhesive coating. As examples of the drying temperature in the above-mentioned drying, a range of 10°C to 35°C can be cited, and as examples of the drying time, a range of 10 minutes to 360 minutes can be cited. In addition, as examples of the heating temperature in the above-mentioned heating, a range of 100°C to 200°C can be cited, and as examples of the heating time, a range of 10 minutes to 360 minutes can be cited. It should be noted that the heating can be carried out under an atmosphere of an inert gas (for example, nitrogen, argon, etc.).

[0120] <Elastic Layer 10D>

[0121] The elastic layer 10D is not particularly limited as long as it has elasticity.

[0122] The elastic layer 10D is provided to impart elasticity to the fixing belt 10 against pressure applied from the outer circumference. It follows the unevenness of the toner image on the recording medium and brings the fixing belt surface into close contact with the toner image.

[0123] The elastic layer 10D is preferably made of an elastic material that can return to its original shape even when deformed by application of an external force of 100 Pa, for example.

[0124] Examples of the elastic material used for the elastic layer 10D include fluororesins, silicone resins, silicone rubber, fluororubber, and fluorosilicone rubber. Silicone rubber and fluororubber are preferred materials for the elastic layer in terms of heat resistance, thermal conductivity, and insulation properties, with silicone rubber being more preferred.

[0125] Examples of silicone rubber include room temperature curing (RTV) silicone rubber, high temperature curing (HTV) silicone rubber, and liquid silicone rubber. Specifically, examples include polydimethylsilicone rubber (MQ), methyl vinyl silicone rubber (VMQ), methylphenyl silicone rubber (PMQ), and fluorosilicone rubber (FVMQ).

[0126] Examples of commercially available silicone rubbers include liquid silicone rubber SE6744 manufactured by Dow Corning.

[0127] Silicone rubbers are preferably crosslinked primarily by addition reaction. Various types of functional groups are known for silicone rubbers, with preferred examples including dimethyl silicone rubber with methyl groups, methylphenyl silicone rubber with both methyl and phenyl groups, and vinyl silicone rubber with vinyl groups (vinyl-containing silicone rubber). Vinyl silicone rubber with vinyl groups is more preferred, and silicone rubbers having an organopolysiloxane structure and a hydrogen organopolysiloxane structure with hydrogen atoms (SiH) bonded to silicon atoms are even more preferred.

[0128] Examples of the fluororubber include vinylidene fluoride rubber, tetrafluoroethylene / propylene rubber, tetrafluoroethylene / perfluoromethyl vinyl ether rubber, phosphazene rubber, and fluoropolyether.

[0129] Examples of commercially available fluororubbers include Viton B-202 manufactured by DuPont Dow Chemical.

[0130] The elastic material used in the elastic layer 10D preferably contains silicone rubber as a main component (ie, contains 50% by mass or more), more preferably 90% by mass or more, and even more preferably 99% by mass or more.

[0131] In addition to the elastic material, the elastic layer 10D may also contain an inorganic filler for the purpose of reinforcement, heat resistance, heat conduction, etc. Examples of the inorganic filler include known materials, preferably fumed silica, crystalline silica, iron oxide, aluminum oxide, and metallic silicon.

[0132] In addition to the materials mentioned above, the materials of the inorganic filler include carbides (for example, carbon black, carbon fibers, carbon nanotubes, etc.), titanium oxide, silicon carbide, talc, mica, kaolin, calcium carbonate, calcium silicate, magnesium oxide, graphite, silicon nitride, boron nitride, cerium oxide, magnesium carbonate and other well-known inorganic fillers.

[0133] Among these, silicon nitride, silicon carbide, graphite, boron nitride, and carbide are preferred from the viewpoint of thermal conductivity.

[0134] The content of the inorganic filler in the elastic layer 10D may be determined according to the required thermal conductivity, mechanical strength, etc., and may be, for example, 1 mass % to 20 mass %, preferably 3 mass % to 15 mass %, and more preferably 5 mass % to 10 mass %.

[0135] The elastic layer 10D may contain additives such as softeners (paraffin wax, etc.), processing aids (stearic acid, etc.), antioxidants (amines, etc.), vulcanizing agents (sulfur, metal oxides, peroxides, etc.), and functional fillers (aluminum oxide, etc.).

[0136] The thickness of the elastic layer 10D may be, for example, in the range of 30 μm to 600 μm, and preferably in the range of 100 μm to 500 μm.

[0137] The elastic layer 10D may be formed by applying a known method, for example, by forming it on the adhesive layer 10C by a coating method.

[0138] When silicone rubber is used as the elastic material for the elastic layer 10D, for example, an elastic layer-forming coating liquid containing liquid silicone rubber (which cures to form silicone rubber upon heating) is first prepared. Next, the elastic layer-forming coating liquid is applied (e.g., by flow coating (spiral coating)) onto the adhesive film formed by applying and drying the adhesive layer-forming coating liquid to form an elastic coating film. The elastic coating film is then vulcanized, for example, as needed, to form the elastic layer on the adhesive layer. The vulcanization temperature during vulcanization is, for example, 150°C to 250°C, and the vulcanization time is, for example, 30 minutes to 120 minutes.

[0139] <Release layer 10E>

[0140] The release layer 10E has the function of preventing the molten toner image from being fixed to the surface (peripheral surface) in contact with the recording medium during fixing.

[0141] The release layer 10E is required to have, for example, heat resistance and release properties. From this perspective, the release layer is preferably made of a heat-resistant release material, specifically fluororubber, fluororesin, silicone resin, polyimide resin, and the like.

[0142] Among these, fluororesin can be used as the heat-resistant release material.

[0143] Specific examples of fluororesins include tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), polyethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), polychlorotrifluorinated ethylene (PCTFE), and polyvinyl fluoride (PVF).

[0144] The elastic layer side of the release layer may be subjected to a surface treatment. The surface treatment may be a wet treatment or a dry treatment, and examples thereof include liquid ammonia treatment, excimer laser treatment, and plasma treatment.

[0145] The thickness of the release layer 10E may be in the range of 10 μm to 100 μm, and more preferably in the range of 20 μm to 50 μm.

[0146] The release layer 10E may be formed by applying a known method, for example, by a coating method.

[0147] Alternatively, the release layer 10E may be formed by preparing a tubular release layer in advance, for example, forming an adhesive layer on the inner surface of the tube, and then coating the outer periphery of the elastic layer 10D to form the release layer 10E.

[0148] <Fixing Unit>

[0149] The fixing device of this embodiment comprises: the fixing belt of the above-mentioned embodiment; a pressing component that pressurizes the outer peripheral surface of the above-mentioned fixing belt and, together with the above-mentioned fixing belt, clamps a recording medium having an unfixed toner image formed on the surface; and an electromagnetic induction device that causes at least a portion of the metal layer of the above-mentioned fixing belt (specifically, the metal heat-dissipating layer) to release heat through electromagnetic induction.

[0150] An example of the fixing device according to this embodiment will be described below, but the present invention is not limited thereto.

[0151] Figure 2 This is a schematic structural diagram showing an example of the fixing device according to the present embodiment.

[0152] The fixing device 100 of this embodiment is an electromagnetic induction type fixing device having the fixing belt of the above-mentioned embodiment. Figure 2 As shown, a pressure roller (pressure member) 11 is arranged to pressurize a portion of the fixing belt 10. To ensure efficient fixing, a contact area (nip) is formed between the fixing belt 10 and the pressure roller 11, and the fixing belt 10 is curved along the circumference of the pressure roller 11. Furthermore, to ensure easy releasability of the recording medium, the fixing belt 10 is curved to form a bent portion at the end of the contact area (nip).

[0153] The pressure roller 11 is constructed by forming an elastic layer 11B made of silicone rubber or the like on a base material 11A, and further forming a release layer 11C made of a fluorine-based compound on the elastic layer 11B.

[0154] An opposing member 13 is disposed inside the fixing belt 10 at a position opposing the pressure roller 11. The opposing member 13 is made of metal, heat-resistant resin, heat-resistant rubber, or the like, and includes a gasket 13B and a support 13A that supports the gasket 13B. The gasket 13B contacts the inner circumference of the fixing belt 10 and locally increases pressure.

[0155] An electromagnetic induction heat radiator 12 having an electromagnetic induction coil (excitation coil) 12a built in is provided at a position facing the pressure roller 11 (an example of a pressure member) centered on the fixing belt 10. In the electromagnetic induction heat radiator (electromagnetic induction device 12), an alternating current is applied to the electromagnetic induction coil, and the magnetic field generated by the excitation circuit changes, and the metal layer 10B (especially the metal layer 10B) of the fixing belt 10 is heated. Figure 1 In the fixing belt of the embodiment shown, eddy currents are generated in the metal heat dissipation layer 104. The eddy currents are converted into heat (Joule heat) by the resistance of the metal layer 10B, resulting in heat dissipation on the surface of the fixing belt 10.

[0156] It should be noted that the position of the electromagnetic induction heat radiator 12 is not limited to Figure 2 The position shown may be set, for example, on the upstream side of the contact region of the fixing belt 10 in the rotation direction B, or may be set on the inner side of the fixing belt 10 .

[0157] In the fixing device 100 of this embodiment, the driving force is transmitted to the gear fixed to the end of the fixing belt 10 by the driving device, so that the fixing belt 10 rotates in the direction of arrow B. As the fixing belt 10 rotates, the pressure roller 11 rotates in the opposite direction, that is, in the direction of arrow C.

[0158] The recording medium 15 on which the unfixed toner image 14 is formed passes through the contact area (nip) between the fixing belt 10 and the pressure roller 11 in the fixing device 100 in the direction of arrow A, and pressure is applied to the unfixed toner image 14 in a molten state to fix it to the recording medium 15.

[0159] <Image Forming Apparatus>

[0160] The image forming device of this embodiment includes: an image retainer; a charging device for charging the surface of the above-mentioned image retainer; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the above-mentioned image retainer; a developing device for developing the electrostatic latent image formed on the surface of the above-mentioned image retainer using a toner to form a toner image; a transfer device for transferring the toner image formed on the surface of the above-mentioned image retainer to a recording medium; and a fixing device of this embodiment for fixing the above-mentioned toner image to the above-mentioned recording medium.

[0161] Figure 3 This is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment.

[0162] like Figure 3 As shown, the image forming device 200 of this embodiment includes: a photosensitive body (an example of an image holding body) 202, a charging device 204, a laser exposure device (an example of a latent image forming device) 206, a mirror 208, a developing device 210, an intermediate transfer body 212, a transfer roller (an example of a transfer device) 214, a cleaning device 216, a static eliminating device 218, a fixing device 100 and a paper feeding device (a paper feeding unit 220, a paper feeding roller 222, a position alignment roller 224 and a recording medium guide 226).

[0163] When image formation is performed using the image forming apparatus 200 , first, the non-contact charging device 204 provided close to the photoreceptor 202 charges the surface of the photoreceptor 202 .

[0164] Laser light corresponding to image information (signals) of each color is irradiated from a laser exposure device 206 onto the surface of the photoreceptor 202 charged by the charging device 204 via a mirror 208 , thereby forming an electrostatic latent image.

[0165] The developing device 210 forms a toner image by applying toner to the latent image formed on the surface of the photoreceptor 202. The developing device 210 includes color developers (not shown) each storing toner of cyan, magenta, yellow, and black. By rotating the developing device 210 in the direction of the arrow, the toner of each color is applied to the latent image formed on the surface of the photoreceptor 202, thereby forming a toner image.

[0166] For the toner images of various colors formed on the surface of the photosensitive body 202, the bias voltage applied between the photosensitive body 202 and the intermediate transfer body 212 is used, and at the contact part between the photosensitive body 202 and the intermediate transfer body 212, the toner images of various colors are transferred to the outer peripheral surface of the intermediate transfer body 212 in an overlapping manner in a manner consistent with the image information.

[0167] The outer peripheral surface of the intermediate transfer body 212 contacts the surface of the photoreceptor 202 and rotates in the direction of arrow E.

[0168] In addition to the photoreceptor 202 , a transfer roller 214 is provided around the intermediate transfer body 212 .

[0169] The intermediate transfer body 212 to which the multicolor toner image is transferred rotates in the direction of arrow E. The toner image on the intermediate transfer body 212 is transferred to the surface of the recording medium 15 conveyed to the contact portion in the direction of arrow A by a paper feed device at the contact portion between the transfer roller 214 and the intermediate transfer body 212.

[0170] It should be noted that the paper feeding toward the contact portion between the intermediate transfer body 212 and the transfer roller 214 is carried out as follows: the recording medium accommodated in the paper feeding unit 220 is pushed up to a position in contact with the paper feeding roller 222 by a recording medium pushing-up mechanism (not shown) built into the paper feeding unit 220. At the moment when the recording medium 15 contacts the paper feeding roller 222, the recording medium is conveyed in the direction of arrow A along the recording medium guide 226 by the rotation of the paper feeding roller 222 and the position alignment roller 224, thereby feeding the paper.

[0171] The toner image transferred to the surface of the recording medium 15 moves in the direction of arrow A. In the contact area (nip) between the fixing belt 10 and the pressure roller 11, the toner image 14 is pressed against the surface of the recording medium 15 in a molten state and fixed thereto. This forms an image fixed to the surface of the recording medium.

[0172] After the toner image is transferred to the surface of the intermediate transfer body 212 , the surface of the photoreceptor 202 is cleaned by the cleaning device 216 .

[0173] The surface of the photoreceptor 202 is cleaned by the cleaning device 216 and then statically removed by the static removing device 218 .

[0174] [Example]

[0175] The present invention will be described in more detail below with reference to the following examples, but the present invention is not limited to the following examples.

[0176] <Example 1>

[0177] (Polyimide base material layer)

[0178] A polyimide resin coating containing repeating units represented by the following structural formula (PI) was formed on the surface of a cylindrical stainless steel mold having an outer diameter of 30 mm. The polyimide coating was peeled off from the surface of the stainless steel mold to obtain an endless belt-shaped polyimide resin substrate layer having an inner diameter of 30 mm, a film thickness of 60 μm, and a length of 390 mm.

[0179] [Chemistry 3]

[0180] (PI)

[0181]

[0182] (Modification of the outer peripheral surface of the base material layer)

[0183] After sandblasting the outer peripheral surface of the polyimide resin base material layer, the polyimide resin base material layer was immersed in an alkaline aqueous solution adjusted to pH 12 for 10 minutes.

[0184] (Metal Layer Formation)

[0185] Next, an electroless nickel plating layer with a thickness of 0.8 μm as a base metal layer, a copper plating layer with a thickness of 10 μm as a metal heat dissipation layer, and a nickel plating layer with a thickness of 10 μm as a metal protective layer were sequentially formed on the outer peripheral surface of the polyimide resin base material layer.

[0186] (Elastic Layer Formation)

[0187] Next, a silicone rubber elastic layer having a film thickness of 200 μm was formed on the outer peripheral surface of the nickel plating layer.

[0188] (Release layer formation)

[0189] Next, a fluororesin tube made of PFA is wrapped around the elastic layer.

[0190] The fixing belt is obtained through the above steps.

[0191] <Example 2>

[0192] A fixing belt was obtained under the same conditions as in Example 1 except that the pH of the alkaline aqueous solution used to modify the outer peripheral surface of the base material layer was set to 12.4.

[0193] <Example 3>

[0194] A fixing belt was obtained under the same conditions as in Example 1 except that the pH of the alkaline aqueous solution used to modify the outer peripheral surface of the base material layer was set to 12.9.

[0195] <Example 4>

[0196] A fixing belt was obtained under the same conditions as in Example 1 except that the pH of the alkaline aqueous solution used to modify the outer peripheral surface of the base material layer was set to 13.2.

[0197] <Example 5>

[0198] A fixing belt was obtained under the same conditions as in Example 1, except that the pH of the alkaline aqueous solution used to modify the outer peripheral surface of the base material layer was set to 13.2 and the time was set to 12 minutes.

[0199] <Example 6>

[0200] A fixing belt was obtained under the same conditions as in Example 1 except that the pH of the alkaline aqueous solution used to modify the outer peripheral surface of the base material layer was 13.2 and the time was 14 minutes.

[0201] <Comparative Example 1>

[0202] A fixing belt was obtained under the same conditions as in Example 1 except that the outer peripheral surface of the base material layer was not modified.

[0203] <Measurement of Imidization Ratio>

[0204] The imidization ratios of the central portion in the thickness direction and the outer peripheral surface of the polyimide resin base material layer in the fixing belt of each example were measured by the above-mentioned method.

[0205] <Interface Adhesion Strength>

[0206] The fixing belts of each example were cut into 20 mm wide cylinders (round cut), which were then cut into long strips to prepare evaluation samples. One end of the short side was bent, and the degree of peeling of the plating layer (i.e., metal layer) from the substrate layer by hand was evaluated according to the following criteria.

[0207] A: Peeling area is less than 50%

[0208] B: The peeling area is 50% or more and less than 95%

[0209] C: Peeling area is more than 95%

[0210] <High-temperature and high-humidity durability evaluation: Evaluation of peeling between the polyimide resin substrate layer and the metal layer after storage in a high-temperature and high-humidity environment>

[0211] The fixing belt of each example was stored in an environment of 150° C. and 100% RH for 96 hours.

[0212] The taken-out fixing belt was observed to visually check whether there was separation between the base material and the metal layer, and evaluated based on the following criteria.

[0213] A: No peeling occurs

[0214] B: Peeling occurs (less than 3 locations)

[0215] C: Peeling occurs (more than 3 locations)

[0216] <Crack Durability Evaluation>

[0217] Each fixing belt was cut into a 20 mm wide cylinder (wheel-cut), which was then cut to produce long strips of evaluation samples. Five evaluation samples were connected into a ring, repeatedly stretched and compressed at curvature radii of R = 15 and R = 4, and then wound on a rotating device. The device was rotated at 400 mm / s while continuously and repeatedly applying a bending load, and the time until cracking occurred was measured.

[0218] [Table 1]

[0219]

[0220] The above results show that the fixing belt of this example has higher high-temperature and high-humidity durability than the fixing belt of the comparative example (ie, the polyimide resin base material layer and the metal layer can be prevented from peeling after storage in a high-temperature and high-humidity environment).

[0221] In particular, it was found that in the fixing belt of this example, when the imidization rate of the outer peripheral surface of the polyimide resin base material layer was set to 60% or more and 80% or less, the crack durability was improved.

Claims

1. A fixing belt, wherein: The fuser belt has: a ring-shaped polyimide resin base material layer having an imidization ratio lower throughout the outer peripheral surface than in the central portion in the thickness direction; a metal layer provided on the outer peripheral surface of the polyimide resin base material layer; and an elastic layer provided on the outer peripheral surface of the metal layer, The polyimide resin base material layer has a thickness of 60 μm to 150 μm.

2. The fixing belt according to claim 1, wherein The imidization rate of the entire outer peripheral surface of the polyimide resin base material layer is 50% or more and 95% or less.

3. The fixing belt according to claim 2, wherein The imidization rate of the entire outer peripheral surface of the polyimide resin base material layer is 60% or more and 90% or less.

4. The fixing belt according to claim 3, wherein The imidization rate of the entire outer peripheral surface of the polyimide resin base material layer is 60% or more and 80% or less.

5. The fixing belt according to claim 1, wherein The absolute value of the difference in imidization rate between the central portion in the thickness direction and the entire outer peripheral surface of the polyimide resin base material layer is 5% or more and 50% or less.

6. The fixing belt according to claim 5, wherein The absolute value of the difference in imidization rate between the central portion in the thickness direction and the entire outer peripheral surface of the polyimide resin base material layer is 10% to 40%.

7. The fixing belt according to claim 6, wherein The absolute value of the difference in imidization rate between the central portion in the thickness direction and the entire outer peripheral surface of the polyimide resin base material layer is 20% or more and 40% or less.

8. The fixing belt according to claim 1, wherein The polyimide resin base material layer is a base material layer containing an aromatic polyimide resin.

9. The fixing belt according to claim 8, wherein The aromatic polyimide resin is a polyimide resin having a structural unit represented by the following general formula (PI1): In the general formula (PI1), R P1 represents phenyl or biphenyl, R P2 represents a divalent aromatic group.

10. The fixing belt according to claim 1, wherein The metal layer has: a base metal layer provided on the outer peripheral surface of the polyimide resin substrate layer; a metal heat dissipation layer provided on the outer peripheral surface of the base metal layer; and A metal protective layer is provided on the outer peripheral surface of the metal heat dissipation layer.

11. A fixing device comprising: The fixing belt according to claim 1; a pressing member for pressing the outer peripheral surface of the fixing belt; and an electromagnetic induction device for causing at least a portion of the metal layer of the fixing belt to release heat by electromagnetic induction, A recording medium having an unfixed toner image formed on its surface is sandwiched between the fixing belt and the pressure member, and the toner image is fixed to the recording medium.

12. An image forming apparatus comprising: Image holding body; a charging device for charging the surface of the image holding member; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the image holding member; a developing device for developing the electrostatic latent image formed on the surface of the image holding member using a toner to form a toner image; a transfer device for transferring the toner image formed on the surface of the image holding member to a recording medium; and The fixing device according to claim 11 fixes the toner image to the recording medium.

Images