JP2012068344A - Endless belt for image forming apparatus and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endless belt for an image forming apparatus that maintains good releasability for a long period compared to a case where a belt is made of a fluorinated polyimide resin having no ether group in a main chain.SOLUTION: A surface layer of an endless belt is constituted so that at least an outer surface of the surface layer is formed of a composite resin composition including 25 to 89.5 wt.% of a fluorinated polyimide resin having an ether group in a main chain, 10 to 70 wt.% of a fluorine resin, and 10 to 50 wt.% of conductive particles.

Description

  The present invention relates to an endless belt for an image forming apparatus and an image forming apparatus.

  An image forming apparatus using an electrophotographic method such as a copying machine or a printer forms a uniform charge on an image carrier made of a photoconductive photosensitive member, and forms an electrostatic latent image with a laser beam or the like that modulates an image signal. After the formation, the electrostatic latent image is developed with charged toner to obtain a visualized toner image. Then, a desired image is obtained by electrostatically transferring the toner image to a recording medium via an intermediate transfer member. As the intermediate transfer member, for example, a polyimide resin (hereinafter, polyimide may be abbreviated as “PI”) is used.

  As a method for producing an endless belt made of PI resin, for example, as described in Patent Documents 1 and 2, a PI precursor solution is applied to the surface of a core body (base material layer) by a dip coating method, There is a method of forming a PI resin film on the outer surface of the core body by drying it in a hot air drying oven or the like and then baking it to a predetermined temperature.

  On the other hand, when an endless belt is used in an electrophotographic apparatus, an endless belt made of PI resin composed of a plurality of layers having a release layer (surface layer) formed on the surface has been proposed (for example, see Patent Document 3).

In this case, silicone resin and fluororesin are mainly used as the release layer, and depending on the application, a resin in which carbon is dispersed to improve conductivity, or an inorganic filler such as SiO ₂ or BaSO ₄ is used. The resin etc. which improved durability by mixing these are used.

  On the other hand, when an endless belt is used in an electrophotographic apparatus, the outer peripheral surface and the inner surface are such that the outer peripheral surface is a smooth surface in terms of image quality and the inner peripheral surface is a rough surface in terms of belt running performance. An endless belt having a different surface roughness from the peripheral surface may be required.

  Specific examples of the fluororesin include fluorinated polyimide, PFA resin (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), and fluorinated acrylic resin. Patent Documents 4, 5, and 6 describe a method using a fluorinated polyimide that does not have an ether group in the main chain as an example of using a fluorinated polyimide that is a resin excellent in film strength and releasability. .

Japanese Patent Laid-Open No. 61-273919 JP 2002-091027 A JP 2000-351466 A Patent publication 3069041 JP 2000-137396 A Patent Publication No. 4215492

  The present invention provides an endless belt for an image forming apparatus capable of maintaining releasability for a long period of time as compared with a case where the main chain is made of a fluorinated polyimide resin having no ether group. With the goal.

  In order to achieve the above object, according to the present invention, the following endless belt for an image forming apparatus and an image forming apparatus are provided.

[1] It has a surface layer, and at least the outer surface of the surface layer has 25 to 89.5% by mass of a fluorinated polyimide resin having an ether group in the main chain, 10 to 70% by mass of a fluororesin, and conductive. An endless belt for an image forming apparatus comprising a composite resin composition containing 10 to 50% by mass of conductive particles.

[2] The fluorinated polyimide resin having an ether group in the main chain is a fluorinated polyamic acid synthesized from at least partly fluorinated acid anhydride and at least partly fluorinated diamines. The endless belt for an image forming apparatus according to the above [1], which is a resin prepared from 1.

[3] The acid anhydride in which at least a part thereof is fluorinated and the diamine in which at least a part thereof is fluorinated are a fluorine group (—F) and / or a perfluoroalkyl group (—C _n F _{2n + 1).} : N is an integer of 1 or more) The endless belt for an image forming apparatus according to the above [2].

[4] The acid anhydride in which at least a part thereof is fluorinated is represented by the following chemical formulas (1) to (3):

  The diamines represented by the above and at least a part of which are fluorinated are represented by the following chemical formula (4):

The endless belt for an image forming apparatus according to [3], which is represented by

[5] The endless belt for an image forming apparatus according to [4], wherein the diamine having at least a part thereof fluorinated is one represented by the following chemical formulas (5) to (15).

[6] A single-layer structure of only the surface layer, a two-layer structure of the surface layer and a base material layer formed so as to be in contact with the surface layer, or the surface layer, the surface layer, and the base material layer The endless belt for an image forming apparatus according to any one of [1] to [5], which has a three-layer structure including an elastic layer formed between the base material layer and the base material layer.

[7] An image forming apparatus using the endless belt for an image forming apparatus according to any one of [1] to [6].

  According to the inventions according to claims 1 to 6, an image forming apparatus capable of maintaining releasability over a long period of time as compared with a case where the main chain is made of a fluorinated polyimide resin having no ether group. An endless belt can be provided.

  According to the seventh aspect of the present invention, it is possible to provide an image forming apparatus in which the smear of the image is suppressed for a long period of time as compared with the case where the endless belt for the image forming apparatus having this configuration is not used.

1 is a perspective view showing an endless belt for an image forming apparatus according to a first embodiment of the present invention (when it has a single-layer structure with only a surface layer). 1B is a longitudinal sectional view of an endless belt for the image forming apparatus shown in FIG. 1A. FIG. It is a cross-sectional view of an endless belt for the image forming apparatus shown in FIG. 1A. It is a perspective view which shows the endless belt for the image forming apparatus which concerns on the 2nd Embodiment of this invention (when it has a 2 layer structure of a surface layer and a base material layer). It is a longitudinal cross-sectional view of the endless belt for image forming apparatuses shown to FIG. 2A. It is a cross-sectional view of an endless belt for the image forming apparatus shown in FIG. 2A. FIG. 10 is a perspective view showing an endless belt for an image forming apparatus according to a third embodiment of the present invention (when it has a three-layer structure of a surface layer, an elastic layer, and a base material layer). 3B is a longitudinal sectional view of an endless belt for the image forming apparatus shown in FIG. 3A. FIG. It is a cross-sectional view of an endless belt for the image forming apparatus shown in FIG. 3A. FIG. 1B is a perspective view showing a state where the endless belt for the image forming apparatus shown in FIG. 1A is supported by a support.

[Endless Belt for Image Forming Apparatus According to First Embodiment]
FIG. 1A is a perspective view showing an endless belt for an image forming apparatus according to the first embodiment of the present invention (when it has a single-layer structure having only a surface layer). 1B is a longitudinal sectional view of an endless belt for the image forming apparatus shown in FIG. 1A. 1C is a cross-sectional view of the endless belt for the image forming apparatus shown in FIG. 1A.

  As shown in FIGS. 1A to 1C, an endless belt 10 for an image forming apparatus according to a first embodiment of the present invention is an image forming apparatus (not shown) that forms an image on a recording member (not shown). 1), an endless belt 10 for an image forming apparatus used as an intermediate transfer belt for transferring an untransferred image onto a recording member, and having a cylindrical surface layer 11 that contacts the recording member during transfer. At least the outer surface of the surface layer 11 includes 25 to 89.5% by mass of a fluorinated polyimide resin having an ether group in the main chain, 10 to 70% by mass of the fluororesin, and 10 to 50% by mass of conductive particles. It consists of a composite resin composition.

  In FIGS. 1A to 1C, as described above, a case where a cylindrical layer is used as the surface layer 11 is shown, but for example, a cylindrical shape such as an elliptic cylinder or a column shape such as a column may be used. Moreover, although the case where the thing of a single layer was used as mentioned above was shown, for example, even if the surface layer 11 itself consists of a plurality of layers, it is composed of a single layer and has ether in the main chain from the inside to the outside. The content of the composite resin composition containing 25 to 89.5% by mass of the fluorinated polyimide resin having a group, 10 to 70% by mass of the fluororesin, and 10 to 50% by mass of the conductive particles is stepwise or inclined. It may increase. In these cases, the outer surface needs to be composed of the composite resin composition described above.

  Note that the endless belt 10 for an image forming apparatus according to the first embodiment has a layer other than the surface layer 11, for example, a base material layer 12 (described later), even if the surface layer 11 itself is composed of a plurality of layers. 2 (see FIG. 2A) and the like, it is included in “when it has a single-layer structure of only the surface layer 11” (that is, when it has no other layer such as a base material layer as the endless belt 10).

  As described above, at least the outer surface of the surface layer 11 of the endless belt 10 for the image forming apparatus according to the first embodiment has a fluorinated polyimide resin having an ether group in the main chain of 25 to 89.5% by mass. And a composite resin composition containing 10 to 70% by mass of a fluororesin and 10 to 50% by mass of conductive particles.

  As this composite resin composition, for example, as a precursor of a fluorinated polyimide resin having an ether group in the main chain, an acid anhydride that is at least partly fluorinated and a diamine that is at least partly fluorinated Prepared from a dispersion as a precursor of a composite resin composition, in which a fluororesin and conductive particles are dispersed in a solution of a fluorinated polyamic acid synthesized from the above (for example, an N-methylpyrrolidone solution). Can be mentioned.

  Moreover, as this composite resin composition, what was prepared by heating the above-mentioned dispersion liquid as a precursor of a composite resin composition can be mentioned, for example.

  Hereinafter, the fluorinated polyimide resin having an ether group in the main chain, the fluororesin, and the conductive particles constituting the composite resin composition will be described in order, and then the fluorinated polyimide resin having an ether group in the main chain will be described. An explanation will be given of preparing a dispersion as a precursor of a composite resin composition by dispersing a fluororesin and conductive particles in a solution of a fluorinated polyamic acid that is a precursor.

First, a fluorinated polyimide resin having an ether group in the main chain will be described. This fluorinated polyimide resin having an ether group in the main chain is used for enabling the endless belt 10 to maintain an appropriate release property for a long period of time. Fluorinated polyamic acid as a precursor of fluorinated polyimide resin having an ether group in the main chain is synthesized from the above-mentioned acid anhydrides that are at least partly fluorinated and diamines that are at least partly fluorinated. As these acid anhydrides and diamines, those having a fluorine group (-F) and / or a perfluoroalkyl group (-C _n F _{2n + 1} : n is an integer of 1 or more) can be mentioned. be able to. _{N in the} perfluoroalkyl group (—C _n F _{2n + 1} ) is preferably 1 to 9, and specific examples include —CF ₃ , —C ₂ F ₅ , —C ₃ F _{7 and the} like. . In addition, at least one of the above-described acid anhydride at least partially fluorinated and diamines at least partially fluorinated must have an ether group in the main chain.

  Specifically, examples of the acid anhydride at least partially fluorinated include those represented by the above chemical formulas (1) to (3).

  The diamines at least partially fluorinated are generally represented by the above chemical formula (4), specifically, for example, those represented by the above chemical formulas (5) to (15). Can be mentioned.

As described above, at least a part of the fluorinated acid anhydride and at least a part of the fluorinated diamine used in the present invention are not only completely fluorinated but also partly fluorinated. Without being fluorinated (without being substituted with a fluorine group (—F) and / or a perfluoroalkyl group (—C _n F _{2n + 1,} where n is an integer of 1 or more)), remain a hydrogen group (—H) Can be used.

  The fluorinated polyimide resin having an ether group in the main chain is usually blended at a ratio of 25 to 89.5% by mass, preferably 35 to 75% by mass with respect to the entire composite resin composition. If it is less than 25% by mass, the endless belt 10 may be difficult to polymerize from a polyamic acid and have a problem of insufficient durability. If it exceeds 75% by mass, there may be a problem that it is difficult to achieve both releasability and electrical resistance control.

  Next, the fluororesin will be described. The fluororesin is used for improving the peelability (release property) on the surface of an endless belt for an image forming apparatus. A fluororesin is normally mix | blended in the ratio of 10-70 mass% with respect to the whole composite resin composition, Preferably, 20-60 mass%. If it is less than 10% by mass, the peelability of the surface of the endless belt 10 may be insufficient. If it exceeds 70% by mass, polymerization of polyamic acid may be hindered and durability may be insufficient.

  As such a fluororesin, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP) and the like are preferable. Among these, polytetrafluoroethylene (PTFE) or tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) is more preferable. The fluororesin used as the dispersant is preferably a particle having an average particle diameter of 0.1 to 1 μm, more preferably 0.1 to 0.3 μm.

  Next, the conductive particles will be described. The conductive particles are used for adjusting a film obtained from the composite resin composition to a desired electric resistance. The conductive particles are usually blended at a ratio of 10 to 50% by mass, preferably 15 to 30% by mass with respect to the entire composite resin composition. When the amount is less than 10% by mass, the amount of charge induced on the surface of the intermediate transfer member is increased by the toner that is electrostatically adsorbed on the surface of the intermediate transfer member. In some cases, a discharge occurs, the toner image becomes blurred and the graininess is deteriorated, and a good output image cannot be obtained. On the other hand, if it exceeds 50% by mass, the electrostatic force that holds the electric charge of the unfixed toner image transferred from the image carrier to the intermediate transfer member becomes difficult to work. Due to the force of the fringe electric field in the vicinity of the edge, the toner is scattered around the image (blur), and an image having a large noise may be formed.

Examples of such conductive particles include carbon black, carbon beads obtained by granulating carbon black, carbon materials such as carbon fiber and graphite, metals or alloys such as nickel, copper, silver, and aluminum, tin oxide, and oxidation. Examples thereof include conductive metal oxides such as titanium, indium oxide, antimony oxide, and SnO ₂ —In ₂ O ₃ composite oxide, and conductive whiskers such as potassium titanate.

Compounding amount of fluororesin (PFTE) and conductive particles (carbon black) and composite resin composition of surface layer (when using fluorinated polyimide (10FEDA + 4FMPD) as fluorinated polyimide resin having ether group in main chain) The result of investigating the relationship with the peeling force of) is shown below. That is, in a system in which carbon black is not blended, the peel strength [N] of the composite resin composition increases as the blending amount of PFTE increases to 0 mass%, 5 mass%, 10 mass%, 20 mass%, and 30 mass%. Decreases to 1.4N, 0.9N, 0.4N, 0.3N, and 0.2N, indicating that the peelability is improved. As described above, the peel strength [N] when the blending amount of PFTE is 30% by mass is 0.2N, which is the peel strength in the case of tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) [ N], and when the blending amount of PFTE is 30% by mass, it can be seen that peelability similar to PFA can be obtained.
Further, in the system in which 50% by mass of carbon black was blended, when the blending amount of PFTE was 20% by mass, the peeling force [N] of the composite resin composition was about 0.4N and did not change. From this, it is understood that the blending amount of the fluororesin in the composite resin composition is usually 10 to 70% by mass, and the conductive particles are usually preferably 10 to 50% by mass.

The outer surface of the surface layer 11 (or at least the outermost layer in the case of a plurality of layers) preferably has a surface resistivity of 10 ⁴ Ω / □ to 10 ¹⁵ Ω / □. The transfer belt is more preferably 10 ⁸ Ω / □ to 10 ¹⁴ Ω / □. The surface resistivity of the surface layer 11 is measured according to JIS K6911 using a circular electrode (for example, “UR Probe” manufactured by Mitsubishi Oil Chemical Co., Ltd., Hiresta IP).

[Endless Belt for Image Forming Apparatus According to Second Embodiment]
FIG. 2A is a perspective view showing an endless belt for an image forming apparatus according to a second embodiment of the present invention (when it has a two-layer structure of a surface layer and a base material layer). 2B is a longitudinal sectional view of an endless belt for the image forming apparatus shown in FIG. 2A. 2C is a cross-sectional view of the endless belt for the image forming apparatus shown in FIG. 2A.

  As shown in FIGS. 2A to 2C, the endless belt 20 for the image forming apparatus according to the second embodiment is a single layer in which the endless belt 10 for the image forming apparatus according to the first embodiment is only a surface layer. Although it differs from the case of having a structure in that it has a two-layer structure of a surface layer and a base material layer, other points are basically the same as in the case of the first embodiment. Specifically, the endless belt 20 for an image forming apparatus according to the second embodiment is placed on a recording member in an image forming apparatus (not shown) that forms an image on a recording member (not shown). An endless belt 20 for an image forming apparatus that is used as an intermediate transfer belt for transferring an untransferred image onto a substrate, and has a cylindrical base layer 22 on which a recording member is to be recorded during transfer. Fluorinated polyimide having a cylindrical surface layer 21 in contact (in other words, the base material layer 22 is provided on the back side of the surface layer 21), and at least the outer surface of the surface layer 21 has an ether group in the main chain It is composed of a composite resin composition containing 25 to 89.5% by mass of resin, 10 to 70% by mass of fluororesin, and 10 to 50% by mass of conductive particles. Hereinafter, differences from the case of the first embodiment will be mainly described.

  The base material layer 22 used in the endless belt 20 for the image forming apparatus according to the second embodiment has a certain strength by separating the function from the surface layer 21 that requires releasability (releasability). Since the amount of the material used can be reduced while maintaining it, it is used to suppress an increase in cost when an expensive fluorinated polyimide resin is used. Further, as in the case of the surface layer 21, the base material layer 22 itself may be a plurality of layers. The thickness of the base material layer 22 is preferably 10 μm to 100 μm, and more preferably 20 μm to 80 μm. If it is less than 10 μm, the strength may be insufficient, and if it exceeds 100 μm, the flexibility may be insufficient.

  It is preferable from an adhesive point that at least the inner surface of the base material layer 22 (which has the same meaning as the outer surface of the surface layer 21) is composed of polyimide, polyamideimide, or polyamide.

  When used as a transfer belt, as in the case of the first embodiment, conductive particles are dispersed in the surface layer 21, but like the surface layer 21, the conductive particles are dispersed in the base material layer 22. It is preferable to disperse. That is, it is preferable that conductive particles are dispersed in the polyimide, polyamideimide or polyamide constituting the base material layer 22 described above.

Examples of the conductive particles include carbon black, carbon beads obtained by granulating carbon black, carbon materials such as carbon fiber and graphite, metals or alloys such as nickel, copper, silver, and aluminum, tin oxide, titanium oxide, and oxide. Examples thereof include conductive metal oxides such as indium, antimony oxide, SnO ₂ —In ₂ O ₃ composite oxide, and conductive whiskers such as potassium titanate. Carbon black having good dispersion maintenance is preferred.

[Endless Belt for Image Forming Apparatus According to Third Embodiment]
FIG. 3A is a perspective view showing an endless belt (when it has a three-layer structure of a surface layer, an elastic layer, and a base material layer) for an image forming apparatus according to a third embodiment of the present invention. 3B is a longitudinal sectional view of an endless belt for the image forming apparatus shown in FIG. 3A. 3C is a cross-sectional view of an endless belt for the image forming apparatus shown in FIG. 3A.

  As shown in FIGS. 3A to 3C, the endless belt 30 for the image forming apparatus according to the third embodiment is a single layer in which the endless belt 20 for the image forming apparatus according to the first embodiment is only a surface layer. Compared to the case of having a structure, the surface layer, the elastic layer, and the base layer have a three-layer structure, but the other points are basically the same as those in the first and second embodiments. is there. Specifically, the endless belt 30 for the image forming apparatus according to the third embodiment is formed on the recording member in an image forming apparatus (not shown) that forms an image on the recording member (not shown). An endless belt 30 for an image forming apparatus that is used as an intermediate transfer belt for transferring an untransferred image onto a substrate, and has a cylindrical base material layer 32 on which a recording member is to be recorded during transfer. It has a cylindrical surface layer 31 in contact (in other words, the base material layer 32 is provided on the back side of the surface layer 31), and further, as an intermediate layer between the surface layer 31 and the base material layer 32. An elastic layer 33 is further provided, and at least the outer surface of the surface layer 31 has 25 to 89.5% by mass of a fluorinated polyimide resin having an ether group in the main chain, 10 to 70% by mass of the fluororesin, and the conductive particles 10. Composed of a composite resin composition containing ˜50 mass% It is made of Te. Hereinafter, differences from the first and second embodiments will be mainly described.

  The elastic layer 33 used in the endless belt 30 for the image forming apparatus according to the third embodiment is used to improve the adhesion with the photoreceptor and stably form the transfer region. As in the case of the surface layer 31, the elastic layer 33 itself may be a plurality of layers.

  For the elastic layer 33, for example, silicone rubber or fluororubber is preferable in terms of heat resistance, cost, and the like.

[Support]
FIG. 4 is a perspective view showing a state in which the endless belt for the image forming apparatus according to the first embodiment shown in FIG. 1A is supported by a support.

  The support 50 is used to support the endless belt when manufacturing or using the endless belt for the image forming apparatus according to the present embodiment.

  Examples of the shape of the support 50 include a columnar shape such as a columnar shape or a cylindrical shape such as a cylindrical shape. In general, the cross section is preferably a circular one as described above, but may have another cross section such as an ellipse.

  The material of the support 50 is preferably a metal such as aluminum, copper, or stainless steel. In this case, in order to improve the peelability of the surface of the support 50, the surface of the support 50 is plated with chromium or nickel, the surface of the support 50 is coated with a fluororesin or silicone resin, or the surface of the support 50 is separated. A mold may be applied.

  On the other hand, when manufacturing an endless belt for an image forming apparatus according to the present embodiment, which will be described later, a coating film of the composite resin composition precursor dispersion is formed on the surface of the support 50 and the formed coating film is heated. In this case, the resulting composite resin composition film may be swollen or defective due to the gas generated by the evaporation of the solvent remaining in the film. From this, in order to effectively release the gas generated in the coating film when the heat treatment is performed, the surface of the support 50 is subjected to blasting so that A rough surface with a roughness Ra of about 0.2 to 1.0 μm may be formed, or cutting may be performed in the circumferential direction of the surface of the support 50.

[Method for producing endless belt for image forming apparatus]
The method for producing an endless belt for an image forming apparatus according to the present embodiment includes an acid anhydride in which at least a part thereof is fluorinated as a precursor of a fluorinated polyimide resin having an ether group in the main chain, and at least a part thereof. As a precursor of a composite resin composition, a fluororesin and conductive particles are dispersed in a solution of a fluorinated polyamic acid synthesized from a fluorinated diamine (for example, an N-methylpyrrolidone solution). A dispersion liquid (varnish) was prepared, and a coating liquid was formed by applying the dispersion liquid (varnish) as a precursor of the obtained composite resin composition to a substrate or a support (hereinafter referred to as “composite resin composition”). A precursor dispersion coating film forming step ”, and the formed coating film is heated to form a film of the composite resin composition constituting at least the outer surface of the surface layer (hereinafter, referred to as“ precursor dispersion coating film forming step ”). `` Composite tree Containing composition coating may be abbreviated as (surface layer) formation process "). In addition to the above steps, other steps such as a drying step of the composite resin composition precursor dispersion coating film may be included as necessary.

  The method for producing an endless belt for an image forming apparatus according to the present embodiment is roughly divided into a single-layer structure in which the endless belt is only a surface layer of the composite resin composition as in the case of the first embodiment. The endless belt as in the case of the second embodiment or the third embodiment, and the case where the single-layer film (surface layer) of the composite resin composition is directly formed on the metal support 50. When the composite resin composition has a two-layer structure of a surface layer and a base material layer, or when it has a three-layer structure of a surface layer, an elastic layer, and a base material layer (combined with an existing endless belt made of polyimide) The case where the resin composition precursor dispersion is coated to form an endless belt having a plurality of layers will be described separately.

<When the endless belt has a single-layer structure consisting only of the surface layer of the composite resin composition>
(Composite resin composition precursor dispersion coating film forming step)
In the composite resin composition precursor dispersion coating film forming step, a dispersion liquid (varnish) as a precursor of the composite resin composition is used to form a coating film on the surface of the support 50. As the fluorinated polyimide precursor having an ether group in the main chain, an acid anhydride which is represented by the above chemical formulas (1) to (3) and at least a part of which is fluorinated, and the above chemical formula (4) Specifically, a fluorinated polyamic acid synthesized from a diamine that is at least partially fluorinated represented by the above chemical formulas (5) to (15) is used. In addition, diamine is so preferable that a fluorination rate is high. In addition, as a solvent for dissolving a fluorinated polyamic acid (fluorinated PI precursor) having an ether group in the main chain (this solvent also functions as a dispersion medium for the fluororesin and conductive particles), N-methylpyrrolidone , N, N-dimethylacetamide, acetamide, N, N-dimethylformamide and the like, known aprotic polar solvents can be used. The concentration, viscosity, etc. of the fluorinated PI precursor solution should be appropriately selected so that the blended amount of the fluorinated polyimide resin in the finally obtained composite resin composition is 25 to 89.5% by mass. Can do. Next, a fluororesin and conductive particles are dispersed in the fluorinated PI precursor solution using a disperser to prepare a composite resin composition precursor dispersion.

  As a method for applying the composite resin composition precursor dispersion on the surface of the support 50, dip coating is performed by immersing the support 50 in the composite resin composition precursor dispersion and pulling it up, depending on the shape of the support 50. The composite resin composition precursor is installed on the surface of the support 50 which is installed so that the axial direction is substantially parallel to the horizontal direction and is rotated in the circumferential direction, from a nozzle or the like installed almost directly above the support 50. A flow coating method in which the support 50 or nozzle is translated in the axial direction while discharging the dispersion, and a blade coating method in which the coating film formed on the surface of the support 50 is metalized with a blade in this flow coating method. Can be used. In the above flow coating method and blade coating method, the coating film formed on the surface of the support 50 is formed in a spiral shape in the axial direction of the support 50, so that a seam can be formed, but the composite resin composition precursor dispersion Since the solvent contained in the liquid is slow to dry at room temperature, the seam is naturally smoothed.

(Drying step of composite resin composition precursor dispersion coating film)
In the drying step of the composite resin composition precursor dispersion coating film, it is preferable to remove the solvent contained in the coating film formed on the surface of the support 50 by heating and drying. The heating temperature is preferably not higher than the boiling point of the solvent to be used. For example, when the solvent is N-methylpyrrolidone (NMP, boiling point 202 ° C.), the range is preferably 70 to 201 ° C., and the solvent is dimethylacetamide (DMAC, boiling point 165 ° C. ), A range of 60 ° C. to 164 ° C. is preferable. More preferably, after heating once at 60 ° C. to 125 ° C., which is 125 ° C. or less at which imidation starts, and removing water that adversely affects imidization dissolved in the solvent, heating is performed at a temperature below the boiling point of the solvent. It is preferred to remove the solvent by step heating. As the temperature of the second stage, for example, when the solvent is N-methylpyrrolidone (NMP, boiling point 202 ° C.), a range of 125 ° C. to 201 ° C. is preferable, and the solvent is dimethylacetamide (DMAC, boiling point 165 ° C.). In some cases, a range of 125 ° C to 164 ° C is preferred. The heating time varies depending on the concentration and film thickness of the applied coating film, but the heating time at each stage is preferably about 10 to 120 minutes. When the coating film formed on the surface of the support 50 is dripped due to the influence of gravity during drying, the support 50 may be heated and dried while rotating at about 10 to 60 rpm with the axial direction horizontal. preferable.

(Composite resin composition film (surface layer) formation process)
Formation of the composite resin composition film by heating of the coating film dried through the drying step of the composite resin composition precursor dispersion coating film is performed at a temperature range from the boiling point of the solvent to about 400 ° C. to 20 to 120 ° C. It is preferable to carry out in about minutes. At that time, it is preferable that the temperature is increased stepwise or slowly at a constant speed until the above temperature is reached, and more preferably, heating and film formation are performed at two or three stages of temperature. In addition, since a firm film | membrane is formed, the one where final temperature is higher, it is preferable to heat at 340 degreeC or more. Next, the endless belt 10 is obtained by peeling the composite resin composition film (surface layer 11) formed on the surface of the support 50 through the above heat treatment from the support 50. The endless belt 10 thus obtained may be further subjected to end slit processing, punching drilling processing, tape winding processing, and the like as necessary.

<When the endless belt has a two-layer structure of a surface layer and a base material layer>
(PI precursor coating film forming process)
In the PI precursor coating film forming step, a polyimide precursor solution is used to form a coating film on the surface of the support 50. As the PI precursor contained in the polyimide precursor solution, a known one can be used. As the solvent for dissolving the PI precursor, known aprotic polar solvents such as N-methylpyrrolidone, N, N-dimethylacetamide, acetamide, N, N-dimethylformamide, and the like can be used. The concentration, viscosity, etc. of the PI precursor solution can be selected as appropriate, and other materials such as conductive particles, additives, etc. can be added to the PI precursor solution as necessary. Good.

  As a method for applying the PI precursor solution to the surface of the support 50, although depending on the shape of the support 50, a dip coating method in which the support 50 is immersed in the PI precursor solution and pulled up, the axial direction is in the horizontal direction. While the PI precursor solution is discharged from the nozzle or the like installed almost directly above the support 50 on the surface of the support 50 that is installed so as to be substantially parallel and rotates in the circumferential direction, A known method such as a flow coating method in which the nozzle is translated in the axial direction and a blade coating method in which the coating film formed on the surface of the support 50 is metalized with a blade can be used. In the flow coating method and the blade coating method, since the coating film formed on the surface of the support 50 is formed in a spiral shape in the axial direction of the support 50, a seam can be formed, but it is included in the PI precursor solution. Since the solvent is slow to dry at room temperature, the seam is naturally smoothed.

(PI precursor drying step)
In the PI precursor drying step, it is preferable to remove the solvent contained in the coating film formed on the surface of the support 50 as described above by heating and drying. The heating temperature is preferably equal to or lower than the boiling point of the solvent used. For example, when the solvent is N-methylpyrrolidone (NMP, boiling point 202 ° C.), the range is preferably 70 to 201 ° C., and the solvent is dimethylacetamide (DMAC, boiling point 165 In the case of (° C.), a range of 60 ° C. to 164 ° C. is preferable. More preferably, after heating once at 60 ° C. to 125 ° C., which is 125 ° C. or less at which imidation starts, and removing water that adversely affects fluorination dissolved in the solvent, heating is performed at a temperature below the boiling point of the solvent. It is preferred to remove the solvent by step heating. As the temperature of the second stage, for example, when the solvent is N-methylpyrrolidone (NMP, boiling point 202 ° C.), a range of 125 ° C. to 201 ° C. is preferable, and the solvent is dimethylacetamide (DMAC, boiling point 165 ° C.). In some cases, a range of 125 ° C to 164 ° C is preferred. Although the heating time varies depending on the concentration and film thickness of the applied coating film, the heating time at each stage is preferably about 10 to 120 minutes. When the coating film formed on the surface of the support 50 is dripped due to the influence of gravity during drying, the support 50 may be heated and dried while rotating at about 10 to 60 rpm with the axial direction horizontal. preferable.

(PI resin film (base material layer) formation process)
Formation of the PI resin film (base material layer 22) by heating the coating film dried through the PI precursor drying step is carried out in the temperature range from the boiling point of the solvent to about 400 ° C. for about 20 to 120 minutes. It is preferable to do. At that time, it is preferable that the temperature is increased stepwise or slowly at a constant speed until the above temperature is reached, and more preferably, heating and film formation are performed at two or three stages of temperature. In addition, since a firm film | membrane is formed, the one where final temperature is higher, it is preferable to heat at 340 degreeC or more.

(Composite resin composition precursor dispersion coating film forming step)
Next, a composite resin composition precursor dispersion coating film is formed on the surface of the PI resin film (base material layer 22). As the fluorinated polyimide precursor having an ether group in the main chain, an acid anhydride in which at least a part thereof is represented by the above chemical formulas (1) to (3) and the above chemical formula (5) to (5) A fluorinated polyamic acid synthesized from a diamine that is at least partially fluorinated represented by (15) is used. In addition, diamine is so preferable that a fluorination rate is high. As a solvent for dissolving the fluorinated PI precursor, a known aprotic polar solvent such as N-methylpyrrolidone, N, N-dimethylacetamide, acetamide, N, N-dimethylformamide or the like can be used. The concentration, viscosity, etc. of the fluorinated PI precursor solution can be appropriately selected as described above. Next, a fluororesin and conductive particles are dispersed in the fluorinated PI precursor solution using a disperser to prepare a composite resin composition precursor dispersion.

  As a method for applying the composite resin composition precursor dispersion on the surface of the PI film (base material layer 22), the PI resin is installed such that the axial direction is substantially parallel to the horizontal direction and is rotated in the circumferential direction. While discharging the composite resin composition precursor dispersion from a nozzle or the like placed almost directly above the PI resin film (base material layer 22) on the surface of the film (base material layer 22), the PI resin film (base material) Layer 22) or a flow coating method in which the nozzle is translated in the axial direction, and in this flow coating method, a blade coating method in which a coating film formed on the surface of the PI resin film (base material layer 22) is metalized with a blade. Can be used.

(Composite resin composition precursor dispersion coating film drying step)
In the composite resin composition precursor dispersion coating film drying step, it is preferable to remove the solvent contained in the coating film formed on the surface of the PI film by heating and drying as described above. The heating temperature is preferably equal to or lower than the boiling point of the solvent used. For example, when the solvent is N-methylpyrrolidone (NMP, boiling point 202 ° C.), the range is preferably 70 to 201 ° C., and the solvent is dimethylacetamide (DMAC, boiling point 165 In the case of (° C.), a range of 60 ° C. to 164 ° C. is preferable. More preferably, after heating at 60 ° C. to 125 ° C., which is 125 ° C. or less at which imidation starts, to remove water that adversely affects fluorination dissolved in the solvent, heating is performed at a temperature below the boiling point of the solvent. It is preferred to remove the solvent by step heating. As the temperature of the second stage, for example, when the solvent is N-methylpyrrolidone (NMP, boiling point 202 ° C.), a range of 125 ° C. to 201 ° C. is preferable, and the solvent is dimethylacetamide (DMAC, boiling point 165 ° C.). In some cases, a range of 125 ° C to 164 ° C is preferred. Although the heating time varies depending on the concentration and film thickness of the applied coating film, the heating time at each stage is preferably about 10 to 120 minutes. When the coating film formed on the surface of the support 50 is dripped due to the influence of gravity during drying, the support 50 may be heated and dried while rotating at about 10 to 60 rpm with the axial direction horizontal. preferable.

(Composite resin composition film (surface layer) formation process)
Formation of the composite resin composition film (surface layer 21) by heating the coating film dried through the composite resin composition precursor dispersion coating film drying step described above is a temperature range from the boiling point of the solvent to about 400 ° C. It is preferable to carry out in about 20 to 120 minutes. At that time, it is preferable that the temperature is increased stepwise or slowly at a constant speed until the above temperature is reached, and more preferably, heating and film formation are performed at two or three stages of temperature. In addition, since a firm film | membrane is formed, the one where final temperature is higher, it is preferable to heat at 340 degreeC or more. Next, the PI resin film (base material layer 22) and the composite resin composition film (surface layer 21) formed on the surface of the support 50 through the above-described heat treatment are peeled from the support 50 to thereby endless belt 20. Get. The endless belt 20 obtained in this way may be further subjected to slit processing, punching drilling processing, tape winding processing, or the like as necessary.

<When the endless belt has a three-layer structure of a surface layer, an elastic layer, and a base material layer>
This is basically the same as “when the endless belt is composed of a plurality of layers of the surface layer and the base material layer” except that the “forming step of the elastic layer 33” described later is added. That is, “PI resin film (base material layer) forming step” in “when the endless belt is composed of a plurality of surface layers and base material layers”, “composite resin composition precursor dispersion coating film forming step” and “ The following “elastic layer forming step” is performed between the “composite resin composition film (surface layer) forming step”.

(Elastic layer formation process)
After applying an adhesive layer for imparting adhesiveness to the surface of the PI resin film (base material layer) 32, a fluororubber solution was applied and air-dried, followed by vulcanization at 230 ° C. for 4 hours for a total of 180 μm. The elastic layer 33 is formed by laminating the fluororubber layers. A precursor coating of a fluorine-containing aromatic ether ketone polymer is formed on the surface of the obtained elastic layer 33 and heated to form a composite resin composition coating (surface layer 31). Finally, an endless belt Get 30.

[Image forming apparatus]
Next, an image forming apparatus using the endless belt of the present embodiment will be described. The image forming apparatus of the present embodiment is not particularly limited as long as it is an intermediate transfer body type image forming apparatus. For example, according to the present invention, a normal monocolor image forming apparatus in which only a single color toner is accommodated in a developing device, and a toner image carried on a latent image carrier such as a photosensitive drum is successively subjected to primary transfer sequentially to an intermediate transfer member. The present invention is applied to a color image forming apparatus, a tandem type color image forming apparatus in which a plurality of latent image carriers having developing units for respective colors are arranged in series on an intermediate transfer member.

An example is a tandem color image forming apparatus. The surface of the photosensitive drum is uniformly charged, and then an electrostatic latent image is formed by a light beam scanning device or the like based on the image information. The electrostatic latent image formed on the photoreceptor is developed by a developing device. The toner image on the photoreceptor corresponding to each of the black developer, the yellow developer, the magenta developer, and the cyan developer is an intermediate transfer member by an electric field formed between the primary transfer roller and the photoreceptor. Once transferred to the belt. The intermediate transfer member to which the toner image is transferred is driven by a drive system including a drive roller, a tension roller, a backup roller, and the like. The recording medium passes between the intermediate transfer belt and the secondary transfer roller, and the toner image on the intermediate transfer body is transferred to the recording medium 3 during that time. The recording medium to which the toner image has been transferred is conveyed to the fixing device by the conveying belt and is fixed by the fixing device.

  Hereinafter, the endless belt for an image forming apparatus of the present invention and the manufacturing method thereof will be described more specifically with reference to examples. Note that the present invention is not limited in any way by the following examples.

  Here, Examples 1 to 5 are endless belts having a single-layer structure with only a surface layer, and Example 6 is Example 7 in the case of an endless belt having a two-layer structure of a surface layer and a base material layer. In Comparative Examples 1 and 2, when a resin having no ether group in the main chain is used as the fluorinated polyimide resin, Comparative Examples 3 to 6 are when the fluororesin and the conductive particles are blended in an unspecified amount. Respectively.

Example 1
Application | coating of the dispersion liquid (varnish) as a precursor of the composite resin composition to the support body 50 surface was implemented as follows using the flow coat apparatus. As a composite resin composition precursor dispersion (varnish), N-methylpyrrolidone as a solvent, an acid anhydride (10FEDA: 1,4-bis (3,4-dicarboxyl) represented by the above chemical formula (2) Trifluorophenoxy) tetrafluorobenzene dianhydride) and the aromatic diamine (6FBAPP: 2,2-bis (p- (p-aminophenoxy) phenyl-1,1,1,) represented by the above chemical formula (15) Polytetrafluoroethylene (PTFE) having an average particle diameter of 0.2 μm in a solution of partially fluorinated polyamic acid obtained by dissolving 60% by mass of partially fluorinated polyamic acid synthesized from 3,3,3-hexafluoropropane) A dispersion (crocodile crocodile) in which 25% by mass of particles and 15% by mass of carbon black (Special Black 4: Degussa) are dispersed Further, as the support 50, an aluminum cylinder having an outer diameter of 366 mm and a length of 600 mm is used, and an aluminum cylinder having a thickness of 6 mm is used, and this surface is subjected to a blast treatment with spherical glass particles, A surface roughness Ra of the surface of the support 50 was prepared to be 0.4 μm, and a silicone release agent (trade name: KS700, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of the support 50. And a baking treatment for 1 hour at 300 ° C. Next, a dispersion (varnish) as a precursor of the composite resin composition described above was applied to the surface of the support 50 using a flow coat apparatus. The film was formed using a heating furnace (inert oven) that was heated at 120 ° C. for 30 minutes, then heated at 200 ° C. for 30 minutes, 250 ° C. for 30 minutes, and finally at 380 ° C. for 30 minutes. Who Then, a composite resin composition film was formed on the surface of the support 50. After cooling to room temperature, the composite resin composition film was peeled off, the belt film thickness was uniform as 50 μm, and only the surface layer of the composite resin composition having no defects was obtained. An endless belt having a single layer structure was obtained, and a release agent was applied to the surface of the support 50 in advance, so that the inner peripheral surface of the endless belt did not adhere to the support 50 at the time of peeling. It was.

(Example 2)
As a fluorinated PI precursor having an ether group in the main chain, an acid anhydride (6FDA: 2,2-bis (3,4-anhydrodicarboxyphenyl) -hexafluoropropane represented by the above chemical formula (3) ) And the aromatic diamine represented by the above chemical formula (15) (6FBAPP: 2,2-bis (p- (p-aminophenoxy) phenyl-1,1,1,3,3,3-hexafluoropropane) An endless belt having a single-layer structure of only a surface layer of a partially fluorinated polyimide having no defect was obtained in the same manner as in Example 1 except that a partially fluorinated polyamic acid synthesized from was used.

(Example 3)
As a fluorinated PI precursor, an acid anhydride represented by the above chemical formula (2) (10FEDA: 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride) and the above chemical formula Except for using a fully fluorinated polyamic acid synthesized from the aromatic diamine represented by (6) (6FMDA: 4,4 ′-(hexafluoroisopropylidene) dianiline), the same as Example 1 Thus, an endless belt having a single-layer structure consisting of only a surface layer of fully fluorinated polyimide having no defect was obtained.

Example 4
As a fluorinated PI precursor, an acid anhydride represented by the above chemical formula (2) (10FEDA: 1,4-bis (3,4-dicarboxytrifluorophenoxy) tetrafluorobenzene dianhydride) and the above chemical formula Example 1 except that a partially fluorinated polyamic acid synthesized from an aromatic diamine represented by (9) (13FPD: 1,4-diamino-2-tridecafluoro-n-hexylbenzene) was used. In the same manner as above, an endless belt having a single layer structure of only a surface layer of partially fluorinated polyimide having no defect was obtained.

(Example 5)
As a fluorinated PI precursor, an acid anhydride represented by the above chemical formula (1) (P6FDA: 3,6-bis (trifluoromethyl) -1,2,4,5-benzenetetracarboxylic dianhydride) And an aromatic diamine represented by the above chemical formula (5) (8FODA: 2,2 ′, 3,3 ′, 5,5 ′, 6,6′-octafluoro-4,4′-diaminodiphenyl ether) Except for using the fully fluorinated polyamic acid thus obtained, an endless belt having a single layer structure of only the surface layer of partially fluorinated polyimide having no defect was obtained in the same manner as in Example 1.

(Example 6)
After a solution containing the PI precursor on the surface of the support 50 is formed using a flow coat apparatus, a film is formed by heating to form a normal PI endless belt, and then a composite resin composition is further formed on the surface using a flow coat apparatus. An endless belt having a two-layer structure of a surface layer and a base material layer was obtained by applying a dispersion liquid (varnish) as a precursor and heating. Details will be described below. As the PI precursor solution, an N-methylpyrrolidone solution (trade name: U varnish, manufactured by Ube Industries, solid content concentration: 18%, viscosity: about 5 Pa · s) was used. Further, as the support 50, an aluminum cylinder having an outer diameter of 366 mm and a length of 600 mm is used, and an aluminum cylinder having a thickness of 6 mm is used. The surface of the support 50 is a surface of the support 50 by blasting with spherical glass particles. Roughness Ra: A surface roughened to 0.4 μm was prepared. Further, a silicone mold release agent (trade name: KS700, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of the support 50 and baked at 300 ° C. for 1 hour. Next, the N-methylpyrrolidone solution of the aforementioned PI precursor was applied to the surface of the support 50 using a flow coat apparatus. Next, heating film formation was performed using a heating furnace (inert oven) purged with nitrogen. After heating at 120 ° C. for 30 minutes, a PI resin film was formed on the surface of the support 50 by heating at 200 ° C. for 30 minutes, 250 ° C. for 30 minutes, and finally 340 ° C. for 30 minutes. Next, the dispersion liquid (varnish) as a precursor of a composite resin composition was apply | coated to the surface which has a single layer structure only of this polyimide base layer using the same flow coat apparatus. As a precursor dispersion (varnish) of the composite resin composition, an acid anhydride (10FEDA: 1,4-bis (3,4-di) represented by the above chemical formula (2) is added to N-methylpyrrolidone as a solvent. Carboxytrifluorophenoxy) tetrafluorobenzene dianhydride) and aromatic diamine (6FBAPP: 2,2-bis (p- (p-aminophenoxy) phenyl-1,1,1) represented by the above chemical formula (15) , 3,3,3-hexafluoropropane) in a partially fluorinated polyamic acid solution in which 60% by mass of a partially fluorinated polyamic acid is dissolved, polytetrafluoroethylene (PTFE) having an average particle size of 0.2 μm is obtained. ) Particles and 30% by mass of carbon black (Special Black 4: Degussa) 10% by mass dispersion ( Next, heating film formation was performed using a nitrogen-substituted heating furnace (inert oven), which was heated at 120 ° C. for 30 minutes, then at 200 ° C. for 30 minutes, and at 250 ° C. for 30 minutes. And finally a method of heating at 340 ° C. for 30 minutes to form a composite resin composition film on the surface of the support 50. After cooling to room temperature, a resin composed of two layers of PI resin and composite resin composition film was supported. An endless belt having a two-layer structure consisting of a base layer of PI resin having no defect and having a belt layer thickness of 70 μm and a surface layer of the composite resin composition was obtained from the body 50. Adhesiveness between PI of each layer. Since the release agent was applied to the surface of the support 50 in advance, it was easy to peel the endless belt from the support 50.

(Example 7)
After a solution containing the PI precursor on the surface of the support 50 is formed using a flow coat apparatus, a film is formed by heating to form a normal PI endless belt, and then an elastic layer is applied and dried. An endless belt having a three-layer structure of a surface layer, an elastic layer and a base material layer was obtained by applying and heating a dispersion (varnish) as a precursor of the composite resin composition. Details will be described below. As the PI precursor solution, an N-methylpyrrolidone solution (trade name: U varnish, manufactured by Ube Industries, solid content concentration: 18%, viscosity: about 5 Pa · s) was used. Further, as the support 50, an aluminum cylinder having an outer diameter of 366 mm and a length of 600 mm is used, and an aluminum cylinder having a thickness of 6 mm is used. The surface of the support 50 is a surface of the support 50 by blasting with spherical glass particles. Roughness Ra: A surface roughened to 0.4 μm was prepared. Further, a silicone mold release agent (trade name: KS700, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the surface of the support 50 and baked at 300 ° C. for 1 hour. Next, the N-methylpyrrolidone solution of the aforementioned PI precursor was applied to the surface of the support 50 using a flow coat apparatus. Next, heating film formation was performed using a heating furnace (inert oven) purged with nitrogen. After heating at 120 ° C. for 30 minutes, a PI resin film was formed on the surface of the support 50 by heating at 200 ° C. for 30 minutes, 250 ° C. for 30 minutes, and finally 340 ° C. for 30 minutes. Next, on the surface of the endless belt, liquid silicone rubber (KE1940-35, liquid silicone rubber A35) adjusted so that the durometer hardness defined by a type A durometer according to JIS-K6253 (1997) is A35. Product, manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to a film thickness of 200 μm and dried to provide a dry liquid silicone rubber layer. And the dispersion liquid (varnish) as a precursor of a composite resin composition was apply | coated to the surface which has this polyimide base layer and an elastic layer using the same flow coat apparatus. As a precursor dispersion (varnish) of the composite resin composition, an acid anhydride (10FEDA: 1,4-bis (3,4-di) represented by the above chemical formula (2) is added to N-methylpyrrolidone as a solvent. Carboxytrifluorophenoxy) tetrafluorobenzene dianhydride) and aromatic diamine (6FBAPP: 2,2-bis (p- (p-aminophenoxy) phenyl-1,1,1) represented by the above chemical formula (15) , 3,3,3-hexafluoropropane) in a partially fluorinated polyamic acid solution in which 60% by mass of a partially fluorinated polyamic acid is dissolved, polytetrafluoroethylene (PTFE) having an average particle size of 0.2 μm is obtained. ) Particles and 30% by mass of carbon black (Special Black 4: Degussa) 10% by mass dispersion ( Next, heating film formation was performed using a nitrogen-substituted heating furnace (inert oven), which was heated at 120 ° C. for 30 minutes, then at 200 ° C. for 30 minutes, and at 250 ° C. for 30 minutes. And finally a method of heating at 340 ° C. for 30 minutes to form a composite resin composition film on the surface of the support 50. After cooling to room temperature, a resin composed of two layers of PI resin and composite resin composition film was supported. The endless belt was peeled from the body 50 and had a three-layer structure of a PI resin base layer having no defects and a belt layer thickness of 70 μm, an elastic layer, and a surface layer of the composite resin composition. Since the release agent was applied to the surface of the support 50 in advance, it was easy to peel the endless belt from the support 50.

(Comparative Example 1)
As the fluorinated PI precursor solution, an acid anhydride (6FDA: 2,2-bis (3,4-anhydrodicarboxyphenyl) -hexafluoropropane) represented by the above chemical formula (3) and the above chemical formula ( 6) Except that an N-methylpyrrolidone solution of a partially fluorinated polyamic acid synthesized from the aromatic diamine represented by (6FMDA: 4,4 ′-(hexafluoroisopropylidene) dianiline) is used. In the same manner as in Example 1, an endless belt having a single-layer structure having only a surface layer of fluorinated polyimide having no defects was obtained. However, this partially fluorinated polyimide film is rigid and lacks flexibility because it does not have an ether bond.

(Comparative Example 2)
The fluorinated PI precursor has the following chemical formula (16):

  An acid anhydride (NTCDA: naphthalene-1,4,5,8-tetracarboxylic dianhydride) and an aromatic diamine (6FMDA: 2,2′-bis) represented by the above chemical formula (7) Except for using a N-methylpyrrolidone solution of a partially fluorinated polyamic acid synthesized from (trifluoromethyl) benzidine), only the surface layer of fluorinated polyimide having no defects is exactly the same as in Example 1. A semiconductive endless belt having a single layer structure was obtained. However, this partially fluorinated polyimide film is rigid and lacks flexibility because it does not have an ether bond.

(Comparative Example 3)
When the amount of partially fluorinated polyamic acid dissolved was 20% by mass, the amount of PTFE particles dispersed was 50% by mass, and carbon black (Special Black 4: manufactured by Degussa) was dispersed in 30% by mass. A semiconductive fluorinated polyimide belt having poor uniformity and very low strength was obtained.

(Comparative Example 4)
Example 1 except that the amount of partially fluorinated polyamic acid dissolved is 90% by mass, PTFE particles are 2% by mass, and carbon black (Special Black 4: manufactured by Degussa) is dispersed by 8% by mass. In the same manner, a semiconductive endless belt having a single-layer structure consisting of only a surface layer of fluorinated polyimide having no defects was obtained.

(Comparative Example 5)
Implemented except that the dispersion amount of PTFE particles was 7% by mass, the dissolved amount of partially fluorinated polyamic acid was 70% by mass, and carbon black (Special Black 4: manufactured by Degussa) was dispersed by 23% by mass. In the same manner as in Example 1, a semiconductive endless belt having a single-layer structure with only a surface layer of fluorinated polyimide having no defects was obtained.

(Comparative Example 6)
Except that the dispersion amount of the fluororesin was 80% by mass, it was produced in the same manner as in Example 1. As a result, a semiconductive fluorinated polyimide belt having many defects and lacking uniformity was obtained.

(Comparative Example 37)
Except that the dispersion amount of carbon black (Special Black 4: manufactured by Degussa) is 55% by mass, the amount of partially fluorinated polyamic acid is 30% by mass, and the amount of PTFE particle dispersion is 15%. In the same manner as in No. 1, a semiconductive endless belt having a single-layer structure with only a surface layer of fluorinated polyimide having no defects was obtained.

(Comparative Example 58)
Implementation was performed except that the carbon black was a dispersion of 7% by mass (special black 4: manufactured by Degussa), 60% by mass of partially fluorinated polyamic acid, and 33% of PTFE particle dispersion. In the same manner as in Example 1, an endless belt having a single-layer structure having only a surface layer of partially fluorinated polyimide having no defect was obtained.

(Evaluation test)
An endless belt using each composite resin composition obtained in Examples 1 to 6 and an endless belt obtained in Comparative Examples 1 to 6 were used as intermediate transfer belts as color composite machines (trade name: DocuColor 8000 Digital Press: It was incorporated into a fixing intermediate transfer device (manufactured by Fuji Xerox Co., Ltd.) and subjected to a durability test and image quality evaluation by continuously feeding 500,000 sheets. In the fixing device incorporating the endless belts of Examples 1 to 7, good durability and image quality were obtained even after continuous feeding of 500,000 sheets. On the other hand, in the intermediate transfer apparatus incorporating the endless belt of Comparative Example 1 or Comparative Example 2, because the film was not flexible, the film ends were broken at the time of 20,000 sheets and 50,000 sheets, respectively. In the intermediate transfer apparatus incorporating the endless belts of Comparative Examples 3 and 6, the image quality was poor and the durability was insufficient due to lack of belt uniformity. In the intermediate transfer apparatus incorporating the endless belt of Comparative Example 4, good image quality could not be obtained due to insufficient peelability in addition to discharge due to high resistance. In the intermediate transfer apparatus incorporating the endless belt of Comparative Example 5, transferability was poor due to lack of peelability, and good image quality could not be obtained. In the intermediate transfer apparatus incorporating the endless belt of Comparative Example 7, the electrical resistance of the transfer belt is as low as 10 ⁵ Ω / □, and the unfixed toner image holding power is weak, so blurring occurs and good image quality can be obtained. There wasn't. In the intermediate transfer apparatus incorporating the endless belt of Comparative Example 8, the electrical resistance was as high as 10 ¹⁶ Ω / □, so that the graininess deteriorated and a good image quality could not be obtained.

DESCRIPTION OF SYMBOLS 10 Endless belt 11 for image forming apparatuses End surface belt 20 Endless belt 21 for image forming apparatuses Surface layer 22 Base material layer 30 Endless belt 31 for image forming apparatuses Surface layer 32 Base material layer 33 Elastic layer 50 Support body

Claims (7)

  It has a surface layer, and at least the outer surface of the surface layer has a fluorinated polyimide resin having an ether group in the main chain of 25 to 80% by mass, a fluororesin of 10 to 65% by mass, and conductive particles of 10 to 50. An endless belt for an image forming apparatus, comprising a composite resin composition containing% by mass.   The fluorinated polyimide resin having an ether group in the main chain is prepared from a fluorinated polyamic acid synthesized from an acid anhydride that is at least partially fluorinated and a diamine that is at least partially fluorinated. The endless belt for an image forming apparatus according to claim 1, wherein the endless belt is a resin. The acid anhydride having at least a part thereof fluorinated and the diamine having at least a part thereof having been fluorinated include a fluorine group (—F) and / or a perfluoroalkyl group (—C _n F _{2n + 1} : n is The endless belt for an image forming apparatus according to claim 2, having an integer of 1 or more. The acid anhydride, at least a part of which is fluorinated, has the following chemical formulas (1) to (3):



The diamines represented by the above and at least a part of which are fluorinated are represented by the following chemical formula (4):

The endless belt for an image forming apparatus according to claim 3, which is represented by: The endless belt for an image forming apparatus according to claim 4, wherein the diamine having at least a part thereof fluorinated is one represented by the following chemical formulas (5) to (15).
The diamines at least partially fluorinated are represented by the following chemical formulas (5) to (15).
The endless belt for an image forming apparatus according to claim 4, wherein










  A single-layer structure of only the surface layer, a two-layer structure of the surface layer and a base material layer formed so as to be in contact with the surface layer, or between the surface layer, the surface layer and the base material layer The endless belt for an image forming apparatus according to any one of claims 1 to 5, wherein the endless belt has a three-layer structure of the formed elastic layer and the base material layer.   An image forming apparatus using the endless belt for an image forming apparatus according to claim 1.