JP2009042394A - Seamless belt for electrophotography, and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seamless belt for electrophotograpy, in particular, a full color intermediate transfer belt, capable of controlling a surface physical property by a method of high productivity favorable for an environment, and capable of providing an image of high quality not generating an abnormal image such as a wormy image. <P>SOLUTION: In this manufacturing method for the seamless belt for the electrophotograpy, a friction coefficient of the seamless belt for the electrophotograpy is made to be less than 0.4, by bringing the seamless belt comprising a resin containing at least a filler into contact with super-critical carbon dioxide or subcritical carbon dioxide dissolved with a low-molecular weight compound to inject the low-molecular weight compound into the seamless belt. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a seamless belt used for electrophotography and a method for producing the same.

In electrophotographic apparatuses, seamless belt members are used for various purposes in the apparatus. For example, a fixing belt, a transfer belt, a paper conveyance belt, and the like can be given.
Among them, in a full-color electrophotographic apparatus, a four-color toner image formed on a photoreceptor is temporarily transferred to an intermediate transfer belt to form a full-color image on the intermediate transfer belt, and then a transfer medium such as paper There is an intermediate transfer belt in a batch transfer system. The demand for intermediate transfer belts has been increasing rapidly as full-color copying machines have been developed.

As the intermediate transfer belt, materials such as thermoplastic resin, thermosetting resin, rubber, and elastomer are used.
However, in this system, in order to obtain high speed, a system called a tandem system in which color developing devices for respective colors facing the intermediate transfer belt are arranged in series is the mainstream. The intermediate transfer belt used in this process does not cause color misregistration due to deformation during running, requires high strength that can withstand repeated use, and also requires flame resistance. Polyamideimide is preferably used.
Also, there are a laminate structure based on polyimide resin for the purpose of improving surface characteristics and a laminate layer of an elastic layer such as rubber or elastomer.

Regardless of the configuration, the intermediate transfer belt forms a toner image on its surface and transfers (transfers) the toner image to a transfer material such as paper. Therefore, the surface is excellent in releasability from the toner. Is required. If the releasability is poor, the image cannot be transferred to paper at the time of transfer, and a part of the image is lost, resulting in a so-called worm-eaten image.
In order not to generate such a worm-eaten image, it has been proposed to define a friction coefficient of the surface.

In Patent Documents 1 to 3, a coating layer of fluorine or silicon is provided on a polyimide base material so that the friction coefficient becomes a specified value. However, since these are all configured to have a surface layer, the configuration is complicated.
In Patent Document 4, it is proposed that the friction coefficient is set to a specified value by including fluorine particles in polyimide. However, in such direct dispersion in polyimide, since the dispersibility of fluorine particles is not good, the contact angle can be a specified value, but the resistance adjustment, for example, the dispersibility of carbon black is impaired, and it is easy to wear and durable. There was a problem of not having sex. In addition, since polyimide is produced at a high temperature, the materials that can be used are limited from the viewpoint of heat resistance.
In Patent Document 5, it is proposed that the friction coefficient on the surface of the photoreceptor and the intermediate transfer member is controlled by applying a lubricant to the surface. This has a wide selection range of the types of the photosensitive member and the intermediate transfer member, but has a problem that the apparatus becomes complicated because a mechanism for applying the lubricant and controlling the coating conditions is necessary.

JP 2002-23514 A JP 2003-57972 A JP 2007-25096 A JP 2004-157221 A JP 2006-330457 A

  The present invention solves the above-described problems of the prior art, and is an electrophotography that can realize a high-quality image that does not cause abnormal images such as worm-eating by controlling surface physical properties by a method that is environmentally friendly and has good productivity. It is an object of the present invention to provide a seamless belt for use in printing, particularly an intermediate transfer belt for full color.

  As a result of intensive studies, the present inventors have injected a seamless belt for electrophotography, particularly an intermediate transfer belt composed of a polyimide resin containing a filler, with supercritical carbon dioxide or subcritical carbon dioxide in which a low-molecular compound is dissolved. It has been found that it can be effectively realized.

That is, the said subject is solved by the following this invention.
(1) “A seamless belt for electrophotography made of a resin containing at least a filler is brought into contact with supercritical carbon dioxide or subcritical carbon dioxide in which a low molecular compound is dissolved, and the low molecular compound is contained in the seamless belt. Injecting the electrophotographic seamless belt, wherein the friction coefficient of the surface of the seamless belt is less than 0.4 ",
(2) “A seamless belt for electrophotography made of a resin containing at least a filler is brought into contact with supercritical carbon dioxide or subcritical carbon dioxide in which a low molecular compound is dissolved, and the low molecular compound is contained in the seamless belt. Electrophotographic seamless belt, wherein the friction coefficient of the surface of the electrophotographic seamless belt is less than 0.4 ",
(3) "The electrophotographic seamless belt according to item (1), wherein the resin is a polyimide resin";
(4) “A plurality of color toner developed images sequentially formed on the image carrier are sequentially superimposed on the intermediate transfer belt for primary transfer, and the primary transfer images are collectively transferred to the recording medium. In a seamless belt for a belt constituent part equipped in an electrophotographic apparatus, the intermediate transfer belt is the seamless belt according to the above item (2) or (3). Seamless belt ",
(5) “A plurality of color toner developed images sequentially formed on the image carrier are sequentially superimposed on the intermediate transfer belt for primary transfer, and the primary transfer images are collectively transferred to the recording medium. In a seamless belt for a belt constituting part equipped in an electrophotographic apparatus, the intermediate transfer belt is the seamless belt according to the item (2) or (3), and the electrophotographic seamless belt A seamless belt for a belt component characterized by having a surface friction coefficient greater than that of the image carrier ",
(6) “A plurality of color toner development images sequentially formed on the image carrier are sequentially superimposed on the intermediate transfer belt to perform primary transfer, and the primary transfer image is collectively transferred to a recording medium. In an electrophotographic apparatus equipped with a belt component, the intermediate transfer belt is the seamless belt according to any one of (2) to (5),
(7) “A plurality of color toner development images sequentially formed on the image carrier are sequentially superimposed on the intermediate transfer belt to perform primary transfer, and the primary transfer images are collectively transferred to a recording medium. In the electrophotographic apparatus equipped with the belt component, the intermediate transfer belt is the seamless belt according to any one of (2) to (5), and the surface friction coefficient is the image carrier surface friction. An electrophotographic apparatus characterized by being larger than the coefficient ".

According to the first and second aspects, it is possible to easily produce an electrophotographic seamless belt having a high productivity and a surface friction coefficient of less than 0.4.
According to the third aspect, the surface friction coefficient can be made more effectively less than 0.4.
According to the fourth aspect, a seamless belt made of polyimide resin having a surface friction coefficient of less than 0.4 can be obtained.
According to the fifth aspect, a full color electrophotographic intermediate transfer belt having a surface friction coefficient of less than 0.4 can be obtained.
According to the sixth aspect of the present invention, it is possible to provide an electrophotographic apparatus having a high quality image that is stable even in an environment using an intermediate transfer belt for full color electrophotography having a surface friction coefficient of less than 0.4.
According to the seventh aspect of the present invention, it is a full-color electrophotographic intermediate transfer belt having a surface friction coefficient of less than 0.4, and is made larger than the surface friction coefficient of the image bearing member, whereby a more stable high quality image electrophotography. It can be a device.

As the resin used for the electrophotographic seamless belt used in the present invention, polyester, polyethylene, polypropylene, polyalkylene terephthalate, polyamide, polyimide, polycarbonate, thermoplastic resins such as fluorine resins such as ABS, PVdF, and ETFE, ester-based, Olefin-based, amide-based, diene-based, silicone-based thermoplastic elastomers, epoxy-based, phenol-based, urethane-based, imide-based, silicone-based thermosetting resins, etc., acrylonitrile rubber, chloroprene rubber, ethylene propylene diene rubber A rubber such as silicon rubber, fluorine rubber, epichlorohydrin rubber or the like is used.
Among these, fluorine resins and imide resins are preferably used particularly in terms of durability and flame retardancy as intermediate transfer belt applications. More preferably, polyimide or polyamideimide resin is applied.

  In particular, a seamless belt made of a polyimide resin in the present invention is preferably formed by applying a solution made of a polyimide precursor using an organic polar solvent as a coating solution and applying the coating solution to a mold.

  The polyimide produced | generated by the heat processing (imidation) of the polyimide precursor which is a component of the coating liquid in this invention is demonstrated in detail.

<Polyimide>
The polyimide used in the present invention is first obtained via a polyamic acid (polyimide precursor) by reaction of a generally known aromatic polycarboxylic acid anhydride or derivative thereof with an aromatic diamine.
That is, polyimide is insoluble in solvents and the like due to its rigid main chain structure and has an infusible property. Therefore, a polyimide precursor that is soluble in an organic solvent from an acid anhydride and an aromatic diamine ( Polyamic acid or polyamic acid) is synthesized, and at this stage, molding is performed by various methods, and then the polyamic acid is subjected to dehydration reaction by heating or a chemical method to be cyclized (imidized) to obtain polyimide. The outline of the reaction is shown in the following chemical reaction formula.

（式中、Ａｒ_１は少なくとも１つの炭素６員環を含む４価の芳香族残基を示し、Ａｒ_２は少なくとも１つの炭素６員環を含む２価の芳香族残基を示す。）

(In the formula, Ar ₁ represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and Ar ₂ represents a divalent aromatic residue containing at least one carbon 6-membered ring.)

  Specific examples of the aromatic polyvalent carboxylic acid anhydride include, for example, ethylenetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4 ′. -Benzophenone tetracarboxylic dianhydride, 2,2 ', 3,3'-benzophenone tetracarboxylic dianhydride, 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 2,2 ', 3,3′-biphenyltetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3 , 4-Dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride Bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxylphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2 , 3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2 , 3,4-benzenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7 , 8-phenanthrenetetracarboxylic dianhydride and the like. These may be used alone or in combination of two or more.

  Next, specific examples of the aromatic diamine to be reacted with the aromatic polycarboxylic acid anhydride include, for example, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, and p-aminobenzyl. Amine, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, bis (3-aminophenyl) sulfide, (3-aminophenyl) (4-aminophenyl) sulfide, bis (4-aminophenyl) sulfide, bis (3-aminophenyl) sulfide, (3-aminophenyl) (4-aminophenyl) sulfoxide, bis (3-aminophenyl) sulfone, (3-aminophenyl) (4-amino Phenyl) sulfone, bis (4-aminophenyl) Ruhon, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, Bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,1- Bis [4- (4-aminophenoxy) phenyl] -ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) ) Phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] butane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3 3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 1,3-bis (3-aminophenoxy) Benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 4,4′-bis (3- Aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] Ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (4-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfoxide, bis [4- (4 -Aminophenoxy) phenyl] sulfoxide, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, Bis [4- (4-aminophenoxy) phenyl] ether, 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 4,4′-bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′- [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4 -Amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone, 1,4-bis [4- (4-aminophenoxy) phenoxy] -Α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, and the like. These are used individually or in mixture of 2 or more types.

  A polyimide precursor (polyamic acid) can be obtained by carrying out a polymerization reaction in an organic polar solvent using substantially equimolar amounts of the aromatic polycarboxylic anhydride component and the diamine component. Below, the manufacturing method of a polyamic acid is demonstrated concretely.

  Examples of the organic polar solvent used in the polymerization reaction of polyamic acid include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide, formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide, N , N-dimethylacetamide, N, N-diethylacetamide and other acetamide solvents, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone and other pyrrolidone solvents, phenol, o-, m-, or p- Phenolic solvents such as cresol, xylenol, halogenated phenol, catechol, ether solvents such as tetrahydrofuran, dioxane, dioxolane, alcohol solvents such as methanol, ethanol, butanol, cellosolve such as butyl cellosolve or hex Methyl phosphoramide, .gamma.-butyrolactone, etc. may be mentioned, it is desirable to use them alone or as a mixed solvent. The solvent is not particularly limited as long as it dissolves polyamic acid, but N, N-dimethylacetamide and N-methyl-2-pyrrolidone are particularly preferable.

  As an example for producing a polyimide precursor, first, one or a plurality of diamines are dissolved in the above organic solvent or diffused in a slurry state in an inert gas atmosphere such as argon or nitrogen. When at least one aromatic polycarboxylic acid anhydride or derivative thereof is added to this solution (either in a solid state, in a solution state dissolved in an organic solvent, or in a slurry state), it generates heat. A ring-opening polyaddition reaction occurs, and the viscosity of the solution rapidly increases, and a high molecular weight polyamic acid solution is obtained. The reaction temperature at this time is preferably controlled to −20 ° C. to 100 ° C., desirably 60 ° C. or less. The reaction time is about 30 minutes to 12 hours.

  The above is an example. Contrary to the addition procedure in the reaction, the aromatic polycarboxylic acid anhydride or derivative thereof is first dissolved or diffused in an organic solvent, and the diamine may be added to this solution. Good. The diamine may be added in a solid state, in a solution state dissolved in an organic solvent, or in a slurry state. That is, the mixing order of the acid dianhydride component and the diamine component is not limited. Further, the aromatic tetracarboxylic dianhydride and the aromatic diamine may be simultaneously added to the organic polar solvent for reaction.

  As described above, the polyamic acid composition is dissolved in the organic polar solvent by polymerizing the aromatic polyvalent carboxylic acid anhydride or derivative thereof and the aromatic diamine component in about an equimolar amount of the organic polar solvent. A polyimide precursor solution is obtained in a uniformly dissolved state.

As the polyimide precursor solution (polyamic acid solution) in the present invention, the one synthesized as described above can be used, but the so-called polyamic acid composition is simply dissolved in an organic solvent. What is marketed as a polyimide varnish can also be obtained and used.
Typical examples include Trenice (manufactured by Toray Industries, Inc.), U-Varnish (manufactured by Ube Industries, Ltd.), Optmer (manufactured by JSR), SE812 (manufactured by Nissan Chemical Industries), CRC8000 (manufactured by Sumitomo Bakelite) It is mentioned as a thing.

  The inorganic filler is mixed and dispersed in the synthesized or obtained polyamic acid solution, and the siloxane compound (polydimethylsiloxane or alkylene oxide-modified polymethylsiloxane) of the present invention is added and mixed to prepare a coating solution. The coating liquid is applied to a support (molding mold) as described later, and then subjected to a treatment such as heating, whereby conversion (imidation) from polyamic acid, which is a polyimide precursor, to polyimide is performed.

That is, the polyamic acid can be imidized by a heating method (1) or a chemical method (2). The heating method (1) is a method of converting polyamic acid to polyimide by heat treatment at 200 to 350 ° C., and is a simple and practical method for obtaining polyimide (polyimide resin). On the other hand, the chemical method (2) is a method in which a polyamic acid is reacted with a dehydrating cyclization reagent (such as a mixture of a carboxylic acid anhydride and a tertiary amine) and then heat-treated to completely imidize, (1 The method (1) is often used because the method is more complicated and costly than the method of heating.
However, recently, although it is a kind of the method (2), a method of promoting imidization at the time of drying by incorporating an amine such as imidazole or quinoline in the varnish as a catalyst is often employed. In order to demonstrate the intrinsic performance of polyimide, it is necessary to complete the imidization by heating above the glass transition temperature of the corresponding polyimide, but this promotes imidization at a lower temperature. It is said that mechanical durability is also improved. However, these catalysts are in very small amounts, and some of them decompose and sublime during drying, but some remain as impurities, which is not preferable.

The progress of imidization (degree of imidization) can be evaluated by a usual method for measuring the imidization rate.
As a method for measuring such an imidization rate, for example, nuclear magnetic resonance spectroscopy calculated from an integration ratio of 1H attributed to an amide group in the vicinity of 9 to 11 ppm and 1H attributed to an aromatic ring in the vicinity of 6 to 9 ppm. Various methods are used such as a method (NMR method), Fourier transform infrared spectroscopy (FT-IR method), a method for quantifying moisture accompanying imide ring closure, and a carboxylic acid neutralization titration method. Outer spectroscopy (FT-IR method) is the most common method.

In Fourier transform infrared spectroscopy (FT-IR method), the imidization rate is defined as follows, for example.
That is, assuming that (A) is the number of moles of imide groups at the firing stage (imidation treatment stage) and (B) is the number of moles of imide groups when 100% imidized (theoretical), Is done.
Imidation rate = [(A)) / (B))] × 100

The number of moles of the imide group in this definition can be determined from the absorbance ratio of the characteristic absorption of the imide group measured by the FT-IR method. For example, as a typical characteristic absorption, the imidization ratio can be evaluated using the following absorbance ratio.
(1) Absorbance ratio between 725 cm ⁻¹ (immobilization band of imide ring C═O group), which is one of characteristic absorptions of imide, and 1,015 cm ⁻¹ of characteristic absorption of benzene rings.
(2) Absorbance ratio between 1,380 cm ⁻¹ (inflection vibration band of imide ring C—N group), which is one of characteristic absorptions of imide, and 1,500 cm ⁻¹ of characteristic absorption of benzene rings.
(3) Absorbance ratio between 1,720 cm ⁻¹ (immobilization vibration band of imide ring C═O group) which is one of characteristic absorptions of imide and 1,500 cm ⁻¹ of characteristic absorption of benzene ring.
(4) 1,720 cm ⁻¹ which is one of characteristic absorptions of imide and 1,670 cm ⁻¹ (interaction between amide group N—H bending vibration and C—N stretching vibration) Absorbance ratio.
Moreover, if it is confirmed that the multiple absorption band derived from the amide group over 3000 to 3300 cm ⁻¹ disappears, the reliability of imidization completion is further increased.

In the present invention, not only the polyimide precursor solution as described above but also a so-called solvent-soluble polyimide that has been imidized in advance and is soluble in an organic polar solvent can be used.
Examples of such materials include Rika Coat (New Nippon Rika) and block copolymerized polyimide (PI Giken).

  In the coating liquid of this invention, you may contain not only the said polyimide but another resin component as needed. Moreover, you may use various additives, such as a leveling agent, a lubricant, antioxidant, a catalyst.

Next, the filler contained as a component of the coating liquid of the present invention will be described.
As the filler, general organic and inorganic materials can be used.
When used as a seamless belt in the present invention, particularly as an intermediate transfer belt, a resistance adjusting material having a resistance adjusting function is used as a filler. The resistance adjusting material is indispensable for adjusting the intermediate transfer belt to a predetermined resistance value.
As the resistance control agent, carbon black, graphite, or metal such as copper, tin, aluminum, indium, tin oxide, zinc oxide, titanium oxide, indium oxide, antimony oxide, bismuth oxide, tin oxide doped with antimony, Examples thereof include fine metal (sub) oxide powders such as indium oxide doped with tin. In addition, as an ion conductive resistance control agent, tetraalkylammonium salt, trialkylbenzyl, ammonium salt, alkylsulfonate, alkylbenzenesulfonate, alkylsulfate, glycerol fatty acid ester, sorbitan fatty acid ester, polyoxyethylene alkylamine Polyoxyethylene fatty alcohol ester, alkyl betaine, lithium perchlorate and the like may be used. Further, polyether amide, polyether ester amide, polypyrrole, polythiophene, polyaniline, or the like which is a conductive polymer may be used. In addition, the resistance control agent in this invention is not limited to these exemplary compounds.

In the present invention, carbon black is preferably used among the resistance control agents.
Examples of the carbon black include furnace black, acetylene black, ketjen black, channel black, and acetylene black. Oxidized carbon black obtained by oxidizing these surfaces is preferable.
Moreover, you may use a dispersion aid as needed. Furthermore, the surface functional group of carbon black and the surface treatment may be performed by reacting an organic compound having reactivity with the functional group.

Next, a method for producing a seamless belt using the coating liquid containing the polyimide precursor will be described.
A step of dispersing a resistance adjuster as necessary, a step of applying and casting a coating solution produced by the step on a support (molding mold), and a coating in a coating applied and cast on the support It is manufactured by removing the solvent by heating, heating and heating to promote imidation of the precursor contained in the coating film, and releasing the formed thin film from the support to form a seamless belt.

In the step of dispersing the resistance adjusting agent, there are a method of dispersing and mixing the resistance control agent directly in the polyimide precursor solution or a method of dispersing the resistance control agent in a solvent in advance and then mixing with the polyimide precursor solution. In particular, the filler for adjusting the resistance is preferably 5 to 25 wt%, more preferably 10 to 20 wt% of the total solid content.
Here, a method of dispersing carbon black as a resistance control agent will be described as an example. Note that this is an example and the present invention is not limited to this.

N-methyl-2-pyrrolidone is mixed with a small amount of carbon black and a polyimide precursor, and dispersed in a ball mill, paint shaker, bead mill or the like for a predetermined time using zirconia beads. After being dispersed to a certain particle size, the liquid taken out is used as a dispersion.
The polyimide precursor solution is mixed with the dispersion to dilute to a predetermined carbon black concentration. As a mixing method at this time, a centrifugal stirrer, a Henschel mixer, a homogenizer, a planetary stirrer, or the like can be used.
If necessary, additives such as a leveling agent and a catalyst can be added at this time.
Further, after stirring, it is preferable to defoam using a vacuum defoamer or the like.

Next, the process of applying the coating solution prepared above will be described.
First, a case where centrifugal molding is used as a support (molding mold) will be described as an example. The following description is an example and the conditions are not limited thereto.
Centrifugal molding is composed of a cylindrical rotating body. While this cylindrical rotating body is slowly rotated, coating and casting (forming a coating film) is performed so that the coating liquid is uniform throughout. . Thereafter, the rotation speed is increased to a predetermined speed, and when the predetermined speed is reached, the rotation speed is maintained at a constant speed and the rotation is continued for a desired time. And the solvent in a coating film is evaporated at the temperature of about 80-150 degreeC, heating up gradually while rotating. In this process, it is preferable to efficiently circulate and remove atmospheric vapor (such as a volatilized solvent). When a self-supporting film is obtained, it is returned to room temperature, transferred to a heating furnace (baking furnace) capable of high-temperature treatment, and subjected to high-temperature heat treatment (baking) at about 250 ° C. to 400 ° C. Imidization is performed. After completion of imidization and the like, the thin film is peeled off from the mold by slow cooling. A seamless belt is thus formed. In addition, it is preferable to form a mold release agent or a mold release layer on the mold so that the mold can be easily peeled off.

  The surface friction coefficient of the polyimide seamless belt thus produced is generally as large as about 0.4 to 0.6. Therefore, the releasability with respect to the toner is insufficient, and a worm-eaten image may be generated due to poor transfer. In order to improve this, there is a method of containing fluorine fine particles, but the dispersibility is poor and it is difficult to obtain a good quality belt.

  Further, it is conceivable to coat the surface of the polyimide seamless belt with a hydrophobic resin such as a fluororesin, but this is also not preferable because of high cost.

  In addition, it is also considered to contain fluorine-based or silicon-based resins and fluorine surfactants, but because of their poor affinity with polyimide resins, they can be contained in very small amounts, or due to the high temperature during polyimide drying. Thermal decomposition may not be effective. Furthermore, it may adversely affect the dispersibility of carbon black, which is a resistance adjusting agent, and may deteriorate electrical characteristics.

Furthermore, when centrifugal molding as described above is performed, fluorine and silicon-based additives tend to be unevenly distributed on the air surface during drying, and are unevenly distributed on the back surface of the belt, so that the surface property cannot be improved.
For this reason, it is necessary not to mold on the inner surface of the mold as in the case of centrifugal molding, but to mold by a method of applying to the outer periphery of the mold.
In the present invention, the seamless belt is effectively and efficiently processed by using a supercritical carbon dioxide field, and the surface friction coefficient is made less than 0.4. For example, when a lubricating material or a repellant is used as a low-molecular compound necessary to reduce the surface friction coefficient to less than 0.4, the amount added is preferably 0.1 to 20 wt%.

Next, the treatment of the seamless belt manufactured as described above with supercritical carbon dioxide will be described.
By placing a seamless belt in a supercritical carbon dioxide field in which a specific low molecular weight compound is dissolved, a low molecular weight compound dissolved in supercritical carbon dioxide is injected into the seamless belt depending on the fluid type, pressure, and temperature conditions. Can be made.
Supercritical carbon dioxide is preferable because it has a low critical temperature among supercritical fluids.
As preferable conditions for the supercritical carbon dioxide or subcritical carbon dioxide treatment, the temperature is 30 to 200 ° C., and the pressure is 7.1 to 60 MPa.
The amount of the low molecular compound injected into the seamless belt is appropriately controlled according to the amount dissolved in supercritical carbon dioxide, pressure, temperature, contact time (flow rate), and the like.
In order to improve the solubility and injectability of the low-molecular compound, in addition to the supercritical carbon dioxide or subcritical carbon dioxide, another liquid (entrainer) can be used in combination as necessary.

There is no restriction | limiting in particular as an apparatus used for a process, Although it can select suitably according to the objective, For example, the pressure vessel (4) for performing the process shown in FIG. 3, and supercritical carbon dioxide are supplied. A pressure pump (1) and a separation tank (9) for separating a gas containing the extracted residue into an extract (10) and a gas (11) after being depressurized by a pressure reducing valve (7). A device is preferably mentioned.
As a treatment method using the apparatus, first, a low molecular compound that can be dissolved in a seamless belt and supercritical carbon dioxide is charged into the pressure vessel (4). Next, the supercritical carbon dioxide is supplied into the pressure vessel (4) by the pressure pump (1), the supercritical carbon dioxide is brought into contact therewith, and the low molecular compound is dissolved and injected into the seamless belt. Let The pressure and temperature conditions at this time are the conditions within the above-described range and the conditions under which the low molecular weight compound is effectively injected into the seamless belt.
The supercritical carbon dioxide is returned to room temperature and normal pressure, and the seamless belt is taken out from the pressure vessel (4).

  According to the above method, a low molecular compound can be effectively injected into the polyimide seamless belt. The friction coefficient of the polyimide seamless belt can be reduced by appropriately selecting this low molecular compound. Further, in this process, since the process is performed not only from the front surface of the belt but also from the back surface, the coefficient of friction on the back surface also decreases. Since the back surface needs to be driven by a driving roller, if it is too low, a drive failure may occur. Therefore, it may be preferable to mask the back surface during this processing.

The low molecular weight compound that prevents the hygroscopic expansion injected into the seamless belt may be any compound that has a number average molecular weight of 10,000 or less, dissolves in supercritical carbon dioxide, and penetrates polyimide. As an effect, a compound having a hydrophobic group is preferred.
Specifically, those having a long-chain aliphatic hydrocarbon group, a fluorine group, or a siloxane group are preferable.

  Examples of the long-chain aliphatic hydrocarbon group-containing compound include natural waxes such as Fischer-Tropsch wax, flax wax, candelilla wax, palm wax, nuka wax, jojoba wax, wood wax, cotton wax, and sugarcane wax. And animal waxes such as beeswax, spermaceti, lanolin and shellac wax, mineral waxes such as ozokerite, ceresin and montan wax, and petroleum waxes such as microcrystalline wax, paraffin wax and pederolatam, etc. Can do.

  Examples of synthetic waxes include synthetic hydrocarbon waxes such as Fischer-Tropsch wax, polyethylene wax, and polypropylene wax. Examples of modified waxes include montan wax derivatives, paraffin wax derivatives, and microcristan wax derivatives. Modified mineral wax or petroleum wax, hardened castor oil, 12-hydroxystearic acid, 12-hydroxystearic acid derivative, fatty acid amide, fatty acid monohydric alcohol ester, fatty acid high alcohol ester, fatty acid amine, waxy dialkyl ketone, etc. Examples include modified products of animal fats and oils.

  In addition, metal soaps such as zinc stearate and calcium stearate are also applicable. Furthermore, a derivative into which a long chain aliphatic hydrocarbon group is introduced can also be used.

Examples of the silicon compound include silicon oil, modified silicone oil, silicon surfactant, silicon wax, silicon resin, and silicon rubber. In addition, a derivative having a polydimethylsiloxane group can be used.
Examples of the fluorine-based compound include a fluorine-based surfactant, a fluorine resin, a fluorine rubber, and a fluorine-modified compound. You may have both functional groups like a fluorinated silicon resin.
Among these, those which are dissolved in supercritical carbon dioxide and fixed in polyimide resin are appropriately selected. For example, a liquid having a too low molecular weight is preferably a solid at room temperature because it bleeds out over a long period of use of the seamless belt and contaminates contact members such as a photoreceptor.

In the above description, the seamless belt of the present invention has been described with respect to a single-layer structure, but is not limited thereto. The present invention can be similarly applied to a structure in which a plurality of layers are stacked.
The present invention is a very versatile and effective means that can treat a material having a surface friction coefficient of less than 0.4 in the same manner for a wide range of material configurations.

Next, the seamless belt used in the belt constituting unit equipped in the electrophotographic apparatus according to the present invention will be described in detail below with reference to a schematic diagram of relevant parts. The schematic diagram is an example, and the present invention is not limited to this.
The schematic diagram of FIG. 1 shows a schematic configuration of the main part of an electrophotographic apparatus equipped with a belt component and the like.
The intermediate transfer unit (500) including the belt member shown in FIG. 1 includes an intermediate transfer belt (501) that is an intermediate transfer member stretched around a plurality of rollers. Around the intermediate transfer belt (501), there are a secondary transfer bias roller (605) as a secondary transfer charge applying means of the secondary transfer unit (600), and a belt cleaning blade (504) as an intermediate transfer body cleaning means. A lubricant application brush (505), which is a lubricant application member of the lubricant application means, is disposed so as to face each other.

  Also, position detection marks (not shown) are provided on the outer peripheral surface or inner peripheral surface of the intermediate transfer belt (501). However, on the outer peripheral surface side of the intermediate transfer belt (501), it is necessary to devise a position detection mark that avoids the passing area of the belt cleaning blade (504), which may be difficult to arrange. In this case, a position detection mark may be provided on the inner peripheral surface side of the intermediate transfer belt (501). The optical sensor (514) serving as a mark detection sensor is provided at a position between the primary transfer bias roller (507) and the belt driving roller (508) on which the intermediate transfer belt (501) is stretched.

  The intermediate transfer belt (501) includes a primary transfer bias roller (507), a belt driving roller (508), a belt tension roller (509), a secondary transfer counter roller (510), which are primary transfer charge applying means, and a cleaning device. It is stretched between the counter roller (511) and the feedback current detection roller (512). Each roller is made of a conductive material, and each roller other than the primary transfer bias roller (507) is grounded. The primary transfer bias roller (507) is controlled by a primary transfer power source (801) controlled by a constant current or a constant voltage so that the current or voltage is controlled to a predetermined magnitude according to the number of superimposed toner images. A bias is applied.

The intermediate transfer belt (501) is driven in the direction of the arrow by a belt drive roller (508) that is driven to rotate in the direction of the arrow by a drive motor (not shown).
The intermediate transfer belt (501) as the belt member is usually a semiconductor or an insulator and has a single-layer or multi-layer structure, but in the present invention, a seamless belt is preferably used, thereby improving durability. In addition, excellent image formation can be realized. In addition, the intermediate transfer belt is set to be larger than the maximum sheet passing size in order to superimpose the toner images formed on the photosensitive drum (200).

  A secondary transfer bias roller (605), which is a secondary transfer means, is in contact with / separating means, which will be described later, with respect to the belt outer peripheral surface of a portion of the intermediate transfer belt (501) stretched around the secondary transfer counter roller (510). It is comprised so that contact / separation is possible by the contact / separation mechanism. The secondary transfer bias roller (605) sandwiches the transfer paper (P) as a recording medium between the secondary transfer counter roller (510) and the intermediate transfer belt (501) stretched between the secondary transfer counter roller (510). A transfer bias having a predetermined current is applied by a secondary transfer power source (802) that is arranged and controlled at a constant current.

  The registration roller (610) is a transfer sheet as a transfer material at a predetermined timing between the secondary transfer bias roller (605) and the intermediate transfer belt (501) stretched around the secondary transfer counter roller (510). Send (P). Further, a cleaning blade (608) as a cleaning unit is in contact with the secondary transfer bias roller (605). The cleaning blade (608) removes and removes adhering material adhering to the surface of the secondary transfer bias roller (605).

  In the color copying machine having such a configuration, when the image forming cycle is started, the photosensitive drum (200) is rotated in a counterclockwise direction indicated by an arrow by a driving motor (not shown), and the photosensitive drum (200) is rotated on the photosensitive drum (200). In addition, Bk (black) toner image formation, C (cyan) toner image formation, M (magenta) toner image formation, and Y (yellow) toner image formation are performed. The intermediate transfer belt (501) is rotated clockwise by the belt driving roller (508) as indicated by an arrow. As the intermediate transfer belt (501) rotates, the primary transfer of the Bk toner image, the C toner image, the M toner image, and the Y toner image is performed by the transfer bias by the voltage applied to the primary transfer bias roller (507). Finally, toner images are formed on the intermediate transfer belt (501) in the order of Bk, C, M, and Y.

For example, the Bk toner image formation is performed as follows.
In FIG. 1, a charging charger (203) uniformly charges the surface of the photosensitive drum (200) to a predetermined potential with a negative charge by corona discharge. The timing is determined based on the belt mark detection signal, and raster exposure with laser light is performed based on the Bk color image signal by a writing optical unit (not shown). When this raster image is exposed, the charge proportional to the exposure light amount disappears in the exposed portion of the surface of the photosensitive drum (200) that is initially charged uniformly, and a Bk electrostatic latent image is formed. When the negatively charged Bk toner on the developing roller of the Bk developing device (231K) comes into contact with this Bk electrostatic latent image, the toner adheres to the portion where the charge of the photosensitive drum (200) remains. In other words, toner is attracted to a portion having no charge, that is, an exposed portion, and a Bk toner image similar to the electrostatic latent image is formed.

  The Bk toner image formed on the photosensitive drum (200) in this way is primary on the belt outer peripheral surface of the intermediate transfer belt (501) rotating at a constant speed while being in contact with the photosensitive drum (200). Transcribed. Some untransferred residual toner remaining on the surface of the photoreceptor drum (200) after the primary transfer is cleaned by the photoreceptor cleaning device (201) in preparation for reuse of the photoreceptor drum (200). Is done. On the photosensitive drum (200) side, the process proceeds to the Y image forming process after the Bk image forming process, and reading of Y image data by a color scanner starts at a predetermined timing. A Y electrostatic latent image is formed on the surface of the body drum (200).

  Then, after the rear end portion of the previous Bk electrostatic latent image passes and before the front end portion of the Y electrostatic latent image arrives, the revolver developing unit (230) is rotated, and the Y developing machine ( 231Y) is set at the development position, and the Y electrostatic latent image is developed with Y toner. Thereafter, the development of the Y electrostatic latent image area is continued, but when the rear end of the Y electrostatic latent image passes, the revolver developing unit is rotated in the same manner as in the previous Bk developing machine (231K). Then, the next C developing machine (231C) is moved to the developing position. This is also completed before the leading edge of the next C electrostatic latent image reaches the developing position. Note that the C and M image forming steps are the same as the Bk and Y steps described above because the color image data reading, electrostatic latent image forming, and developing operations are the same as those described above.

The Bk, Y, C, and M toner images sequentially formed on the photosensitive drum (200) in this manner are sequentially aligned on the same surface on the intermediate transfer belt (501) and primarily transferred. As a result, a toner image having a maximum of four colors superimposed on the intermediate transfer belt (501) is formed. On the other hand, at the time when the image forming operation is started, the transfer paper P is fed from a paper feed unit such as a transfer paper cassette or a manual feed tray, and is waiting at the nip of the registration roller (610).
Then, on the intermediate transfer belt (501), the intermediate transfer belt (501) stretched around the secondary transfer counter roller (510) and the secondary transfer bias roller (605) form a nip. When the leading edge of the toner image approaches, the registration roller (610) is driven so that the leading edge of the transfer paper (P) coincides with the leading edge of the toner image, and is transferred along the transfer paper guide plate (601). The paper (P) is conveyed and registration of the transfer paper (P) and the toner image is performed.

  In this way, when the transfer paper (P) passes through the secondary transfer portion, the intermediate transfer belt (501) is transferred by the transfer bias generated by the voltage applied to the secondary transfer bias roller (605) by the secondary transfer power source (802). ) The four-color superimposed toner image on the top is transferred onto the transfer paper (P) at once (secondary transfer). This transfer paper (P) is conveyed along the transfer paper guide plate (601) and passes through a portion facing the transfer paper neutralization charger (606) comprising a static elimination needle disposed downstream of the secondary transfer portion. After being neutralized by this, the belt is conveyed toward the fixing device (270) by the belt conveying device (210) which is a belt component (see FIG. 1). Then, after the toner image is melted and fixed at the nip portion of the fixing rollers (271) and (272) of the fixing device (270), the transfer paper (P) is sent out of the apparatus main body by a discharge roller (not shown). Stacked face up on a copy tray (not shown). Note that the fixing device (270) may be configured to include a belt component if necessary.

  On the other hand, the surface of the photosensitive drum (200) after the belt transfer is cleaned by the photosensitive member cleaning device (201) and is uniformly discharged by the discharging lamp (202). The residual toner remaining on the outer peripheral surface of the intermediate transfer belt (501) after the toner image is secondarily transferred to the transfer paper (P) is cleaned by the belt cleaning blade (504). The belt cleaning blade (504) is configured to contact and separate at a predetermined timing with respect to the belt outer peripheral surface of the intermediate transfer belt (501) by a cleaning member separating and contacting mechanism (not shown).

  A toner seal member (503) that contacts and separates from the belt outer peripheral surface of the intermediate transfer belt (501) is provided on the upstream side of the belt cleaning blade (504) in the moving direction of the intermediate transfer belt (501). Yes. The toner seal member (503) receives the falling toner dropped from the belt cleaning blade (504) during cleaning of the residual toner, and the falling toner is scattered on the transfer path of the transfer paper (P). It is preventing. The toner seal member (503) is brought into contact with and separated from the belt outer peripheral surface of the intermediate transfer belt (501) together with the belt cleaning blade (504) by the cleaning member separating and contacting mechanism.

  The lubricant (506) scraped by the lubricant application brush (505) is applied to the belt outer peripheral surface of the intermediate transfer belt (501) from which the residual toner has been removed in this way. The lubricant (506) is made of, for example, a solid body such as zinc stearate, and is disposed so as to come into contact with the lubricant application brush (505). Further, residual charges remaining on the outer peripheral surface of the intermediate transfer belt (501) are removed by a neutralizing bias applied by a belt neutralizing brush (not shown) in contact with the outer peripheral surface of the intermediate transfer belt (501). Here, the lubricant application brush (505) and the belt neutralizing brush are brought into and out of contact with the outer peripheral surface of the intermediate transfer belt (501) at a predetermined timing by a contact / separation mechanism (not shown). It has become.

  Here, at the time of repeat copy, the operation of the color scanner and the image formation on the photosensitive drum (200) are performed at a predetermined timing following the image formation process for the fourth color (M) of the first sheet. The process proceeds to the image forming process for the first color (Bk). The intermediate transfer belt (501) has two sheets in the area cleaned by the belt cleaning blade (504) on the outer peripheral surface of the belt following the batch transfer process of the first four-color superimposed toner image to the transfer paper. The Bk toner image of the eye is primarily transferred. After that, the operation is the same as the first sheet. The above is a copy mode for obtaining a four-color full-color copy. In the three-color copy mode and the two-color copy mode, the same operation as described above is performed for the designated color and number of times. In the case of the single color copy mode, only the developing device of the predetermined color of the revolver developing unit (230) is set in the developing operation state until the predetermined number of sheets is completed, and the belt cleaning blade (504) is moved to the intermediate transfer belt (501). The copy operation is performed with the touch panel kept in contact.

In the above embodiment, the copying machine having only one photosensitive drum has been described. However, in the present invention, for example, a plurality of photosensitive drums as shown in FIG. 2 are arranged side by side along one intermediate transfer belt. It can also be applied to an image forming apparatus.
FIG. 2 shows a four-drum type digital color printer having four photosensitive drums (21BK, 21Y, 21M, 21C) for forming toner images of four different colors (black, yellow, magenta, cyan). An example of the configuration is shown.

  In FIG. 2, the printer main body (10) includes an image writing unit (12), an image forming unit (13), and a paper feeding unit (14) for performing color image formation by electrophotography. Based on the image signal, the image processing unit converts the image into black (BK), magenta (M), yellow (Y), and cyan (C) color signals for image formation, and the image writing unit (12). Send to. The image writing unit (12) is a laser scanning optical system including, for example, a laser light source, a deflector such as a rotary polygon mirror, a scanning imaging optical system, and a mirror group. Image writing corresponding to each color signal is performed on an image carrier (photoreceptor) (21BK, 21M, 21Y, 21C) provided for each color of the image forming unit (13).

  The image forming unit (13) includes photosensitive members (21BK, 21M, 21Y, and 21C) that are image carriers for black (BK), magenta (M), yellow (Y), and cyan (C). I have. As each photoconductor for each color, an OPC photoconductor is usually used. Around each photosensitive member (21BK, 21M, 21Y, 21C), there are a charging device, a laser beam exposure unit from the writing unit (12), and a developing device (20BK) for each color of black, magenta, yellow, and cyan. , 20M, 20Y, 20C), a primary transfer bias roller (23BK, 23M, 23Y, 23C) as a primary transfer unit, a cleaning device (not shown), a photoconductor neutralizing device (not shown), and the like. . The developing device (20BK, 20M, 20Y, 20C) uses a two-component magnetic brush developing system. The intermediate transfer belt (22), which is a belt component, is interposed between each photoconductor (21BK, 21M, 21Y, 21C) and each primary transfer bias roller (23BK, 23M, 23Y, 23C). The toner images of the respective colors formed on the photoconductor are sequentially superimposed and transferred.

  On the other hand, the transfer paper (P) is fed from the paper feeding section (14) and then carried on the transfer conveyance belt (50), which is a belt constituting section, via the registration rollers (16). When the intermediate transfer belt (22) and the transfer conveying belt (50) come into contact with each other, the toner image transferred onto the intermediate transfer belt (22) is transferred to a secondary transfer bias roller (60) as a secondary transfer unit. ) For secondary transfer (collective transfer). Thereby, a color image is formed on the transfer paper (P). The transfer paper (P) on which the color image is formed is conveyed to the fixing device (15) by the transfer conveying belt (50). After the image transferred by the fixing device (15) is fixed, the transfer paper (P) To be discharged.

  Residual toner remaining on the intermediate transfer belt (22) without being transferred during the secondary transfer is removed from the intermediate transfer belt (22) by the belt cleaning device (25). A lubricant application device (not shown) is disposed on the downstream side of the belt cleaning device (25). This lubricant application device includes a solid lubricant and a conductive brush that rubs the intermediate transfer belt (22) to apply the solid lubricant. The conductive brush is always in contact with the intermediate transfer belt (22) and applies a solid lubricant to the intermediate transfer belt (22). The solid lubricant has an effect of improving the cleaning property of the intermediate transfer belt (22), preventing the occurrence of filming and improving the durability.

  The seamless belt according to the present invention can be preferably applied to an intermediate transfer belt type image forming apparatus equipped with the intermediate transfer belt (501) or (22) as described above, and the intermediate transfer belt (501) or ( The present invention can also be applied to a transfer / conveying belt type image forming apparatus equipped with a transfer / conveying belt instead of 22). Further, in the case of an image forming apparatus using a transfer / conveying belt system, the present invention can be applied to either the 1-photosensitive drum system or the 4-photosensitive drum system.

In the electrophotographic apparatus as described above, it is important to transfer the color toner image transferred from the photosensitive member to the intermediate transfer belt to the paper, but it is important that the surface of the intermediate transfer belt is not releasable. A part of the toner remains without being transferred. For this reason, for example, an image in which a part of the image is missing as shown in FIG.
However, in the present invention, this can be prevented by making the friction coefficient of the belt surface less than 0.4 by the above-mentioned means.

  However, if the friction coefficient on the surface of the intermediate transfer belt is lowered, a transfer failure from the photoconductor to the intermediate transfer belt occurs when transferring a single color image (primary transfer) from the photoconductor to the intermediate transfer belt. Insect erosion occurs during transcription. This phenomenon can be prevented if the friction coefficient of the photosensitive member is smaller than that of the intermediate transfer belt.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by these examples without departing from the gist thereof.

Example 1
<Preparation of intermediate transfer belt>
[Preparation of coating solution]
First, the following constituent materials were mixed and dispersed using a zirconia bead of φ1 mm for 5 hours with a bead mill disperser to prepare a carbon dispersion.
<Dispersion composition material>
Polyimide solution U-varnish A (Ube Industries; solid content 18%) 2 parts by weight Carbon black Special black 4 (Degussa) 10 parts by weight N-methyl-2-pyrrolidone (Mitsubishi Chemical) 88 parts by weight Using the above dispersion, The constituent materials were mixed, mixed and defoamed with a centrifugal stirring deaerator to obtain a coating solution.
<Coating liquid constituent material>
Carbon black dispersion 50 parts by weight Polyimide solution U-varnish A (Ube Industries; solid content 18 wt%) 50 parts by weight Polyether-modified silicon FZ2105 (Toray Dow Corning) 0.01 part by weight

[Production of seamless belt]
Next, a metal cylinder having an inner diameter of 100 mm and a length of 300 mm having a mirror-finished inner surface is used as a mold, and the coating liquid is uniformly cast on the inner surface of the cylinder while rotating the cylinder at 50 rpm (times / minute). And then applied as if to flow. When the coating has spread evenly after the predetermined total amount has been flowed, the number of revolutions is increased to 500 rpm, the hot air circulating dryer is introduced, the temperature is raised to 100 ° C. at a temperature rising rate of 5 ° C./min, and heated for 30 minutes. did. Thereafter, the rotation was stopped, the mixture was put into a heating furnace (firing furnace) capable of high temperature treatment, heated to 320 ° C. at a temperature rising rate of 3 ° C./min, and subjected to heat treatment (firing) for 60 minutes.
After stopping the heating by treating for a predetermined time, the mold was taken out after gradually cooling to room temperature, and the formed coating film was peeled off from the inner surface of the cylinder to obtain a seamless belt having a film thickness of 70 μm.

[Supercritical carbon dioxide treatment of seamless belt]
The produced seamless belt and 0.7 g of the following compound were put into the pressure cell (4) of the injection tank (internal volume 700 ml) of the apparatus in FIG. 3, and the pressure cell was sealed.
・ Modiper FS700 (Nippon Yushi Co., Ltd. silicone graft polymer)

Next, carbon dioxide was supplied to the pressure cell by a supply cylinder, adjusted to 30 MPa and 40 ° C. with a pressure pump and temperature adjusting means, and after the temperature and pressure were stabilized, the pressure cell was sealed and allowed to stand for 1 hour. After standing, the pressure is reduced to 10 MPa while keeping the temperature at 40 ° C., and carbon dioxide is allowed to flow for 30 minutes at a flow rate of 8 l / min using a pressure pump and a back pressure valve while maintaining this pressure. Excess compound that was not injected into the seamless belt was removed from the pressure cell. After the removal, the seamless belt described in the present invention was obtained by gradually lowering the temperature and pressure to the air atmosphere.
Both the front and back surfaces of the belt were glossy, smooth and good surface properties.

(Example 2)
Example 1 was the same as Example 1 except that the compound used for supercritical carbon dioxide treatment in Example 1 was changed to the following. Both the belt surface and the back surface were glossy and good surface property belts.
BY16-140 (Toray Dow Corning Dimethylsiloxane)

(Example 3)
Example 1 was the same as Example 1 except that the compound used for supercritical carbon dioxide treatment in Example 1 was changed to the following. Both the belt surface and the back surface were glossy and good surface property belts.
・ FZ-49 (alkyl modified siloxane manufactured by Toray Dow Corning)

Example 4
Example 1 was the same as Example 1 except that the compound used for supercritical carbon dioxide treatment in Example 1 was changed to the following. Both the belt surface and the back surface were glossy and good surface property belts.
・ P110 (Mitsui Chemicals polyethylene wax)

(Comparative Example 1)
It was the same except that the supercritical carbon dioxide treatment in Example 1 was not performed.
Both the belt surface and the back surface were glossy and good surface property belts.

(Comparative Example 2)
<Preparation of intermediate transfer belt>
[Preparation of coating solution]
First, the following constituent materials were mixed and dispersed using a zirconia bead of φ1 mm for 5 hours with a bead mill disperser to prepare a carbon dispersion.
<Dispersion composition material>
Polyimide solution U-varnish A (Ube Industries; solid content 18%) 2 parts by weight Carbon black Special black 4 (Degussa) 10 parts by weight N-methyl-2-pyrrolidone (Mitsubishi Chemical) 88 parts by weight Using the above dispersion, The constituent materials were mixed, mixed and defoamed with a centrifugal stirring deaerator to obtain a coating solution.
<Coating liquid constituent material>
Carbon black dispersion 50 parts by weight Polyimide solution U-varnish A (Ube Industries; solid content 18 wt%) 50 parts by weight Modiper FS700 (manufactured by NOF Corporation) 2 parts by weight Polyether-modified silicon FZ2105 (Toray Dow Corning) 0.01 Parts by weight

[Production of seamless belt]
Next, a metal cylinder having an inner diameter of 100 mm and a length of 300 mm having a mirror-finished inner surface is used as a mold, and the coating liquid is uniformly cast on the inner surface of the cylinder while rotating the cylinder at 50 rpm (times / minute). And then applied as if to flow. When the coating has spread evenly after the predetermined total amount has been flowed, the number of rotations is increased to 500 rpm, it is put into a hot air circulating dryer, heated to 100 ° C. at a heating rate of 5 ° C./min, and heated for 60 minutes. did. Thereafter, the rotation was stopped, the mixture was put into a heating furnace (baking furnace) capable of high temperature treatment, heated to 320 ° C. at a heating rate of 5 ° C./min, and subjected to heat treatment (baking) for 60 minutes.
After stopping the heating by treating for a predetermined time, the mold was taken out after gradually cooling to room temperature, and the formed coating film was peeled off from the inner surface of the cylinder to obtain a seamless belt having a film thickness of 70 μm.
The back of the belt was cloudy and had no gloss.

(Comparative Example 3)
The coating solution prepared in Comparative Example 2 was applied to the outer peripheral surface of a metal cylinder having a mirror-finished outer surface with an outer diameter of 100 mm and a length of 300 mm while controlling the amount of adhesion with a dispenser and rotating.
After coating, the outer periphery was heated with a heater so that the surface temperature was 120 ° C. and dried for 60 minutes.
Next, this was put into a heating furnace (firing furnace) capable of high temperature treatment, heated to 320 ° C. at a temperature rising rate of 5 ° C./min, and heat-treated (firing) for 60 minutes.
After stopping the heating by treating for a predetermined time, the mold was taken out after gradually cooling to room temperature, and the formed coating film was peeled off from the inner surface of the cylinder to obtain a seamless belt having a film thickness of 70 μm.
The belt surface was cloudy and had no gloss.

The friction coefficient of the surface of each seamless belt was measured with a DFPM type friction coefficient measuring device (manufactured by Kyowa Interface Science Co., Ltd.).
As the measurement conditions, the average value of the static friction coefficient values continuously measured under the following conditions is adopted.
Friction indenter; SUS ball (point contact)
Weight: 50g
Friction speed: 0.1 mm / sec
Measurement length: 20mm

Further, each of the seamless belts was mounted as an intermediate transfer belt of the electrophotographic apparatus shown in FIG. 2, and the worm-eaten images in the initial image and the full-color image after outputting 10,000 sheets were evaluated in the following ranks.
Rank 3: No worm-eating image Rank 2: There are several worm-eating images.
Rank 1: A large number of worm-eaten images can be seen.

  The photoreceptor provided in the electrophotographic apparatus shown in FIG. 2 has a surface friction coefficient of 0.15, in which the outermost surface is coated with a surface layer in which fluororesin particles are dispersed.

(Example 5)
As the photosensitive member equipped in the electrophotographic apparatus of FIG. 2, a photosensitive member having a surface friction coefficient of 0.45 not coated with a surface layer dispersed with fluororesin particles was used, and the belt of Example 1 was used as an intermediate transfer belt.
The results are shown in Table 1.

  As shown in Table 1, in the present invention, the belt surface properties can be easily processed even for resins such as polyimide with high productivity, and stable for a long period of time by making the friction coefficient of the belt surface less than 0.4. Thus, a full-color electrophotographic apparatus that provides a good image free of worm-eaten images can be obtained.

It is a principal part schematic diagram for demonstrating the seamless belt and apparatus used for the belt structure part of the electrophotographic apparatus which concerns on this invention. FIG. 3 is a schematic diagram illustrating a main part of a configuration example in which a plurality of photosensitive drums are arranged in parallel along one intermediate transfer belt provided in a belt configuration unit of the electrophotographic apparatus according to the present invention. It is a schematic diagram of a supercritical carbon dioxide processing apparatus. It is a figure which shows a worm-eaten image.

Explanation of symbols

(Figure 1)
P Transfer paper 70 Static elimination roller 80 Ground roller 200 Photosensitive drum 201 Photoconductor cleaning device 202 Static elimination lamp 203 Charging charger 204 Potential sensor 205 Toner image density sensor 210 Belt conveyor 230 Revolver developing unit 231Y Y developing machine 231K Bk developing machine 231C C Developer 231M M Developer 270 Fixing device 271, 272 Fixing roller 500 Intermediate transfer unit 501 Intermediate transfer belt 503 Toner seal member 504 Belt cleaning blade 505 Lubricant application brush 506 Lubricant 507 Primary transfer bias roller 508 Belt drive roller 509 Belt Tension controller 510 Secondary transfer counter roller 511 Cleaning counter roller 512 Feedback current detection roller 513 Toner image 514 Optical sensor 6 00 Secondary transfer unit 601 Transfer paper guide plate 605 Secondary transfer bias roller 606 Transfer paper neutralization charger 608 Cleaning blade 610 Registration roller 801 Primary transfer power source 802 Secondary transfer power source (FIG. 2)
P Transfer paper 10 Printer body 12 Image writing unit 13 Image forming unit 14 Paper feeding unit 15 Fixing device 16 Registration rollers 20BK, 20M, 20Y, 20C Developing devices 21BK, 21M, 21Y, 21C Photoconductor 22 Intermediate transfer belts 23BK, 23M , 23Y, 23C Primary transfer bias roller 25 Belt cleaning device 50 Transfer conveyance belt 60 Secondary transfer bias roller (FIG. 3)
1 High-pressure liquid feed pump 2 Stop valve 3 Filter 4 Extraction tank (pressure vessel)
5 Stirrer 6 Filter 7 Pressure reducing valve 8 Flow meter 9 Separation tank 10 Extract 11 Extracted gas T Thermometer P Pressure gauge (FIG. 4)
41; color image part 42; worm-eaten part

Claims (7)

Contacting a seamless belt for electrophotography made of a resin containing at least a filler with supercritical carbon dioxide or subcritical carbon dioxide in which a low molecular compound is dissolved, and injecting the low molecular compound into the seamless belt The method for producing an electrophotographic seamless belt characterized in that the friction coefficient of the surface of the seamless belt is less than 0.4. An electrophotographic seamless belt made of a resin containing at least a filler is brought into contact with supercritical carbon dioxide or subcritical carbon dioxide in which a low molecular compound is dissolved, and the low molecular compound is injected into the seamless belt. The electrophotographic seamless belt is characterized in that the surface friction coefficient of the electrophotographic seamless belt is less than 0.4. The electrophotographic seamless belt according to claim 2, wherein the resin is a polyimide resin. An electrophotographic apparatus for performing a primary transfer by sequentially superimposing a plurality of color toner developed images sequentially formed on an image carrier on an intermediate transfer belt, and performing a secondary transfer of the primary transfer image collectively to a recording medium. A seamless belt for a belt constituent part, wherein the intermediate transfer belt is the seamless belt according to claim 2 or 3. An electrophotographic apparatus for performing a primary transfer by sequentially superimposing a plurality of color toner developed images sequentially formed on an image carrier on an intermediate transfer belt, and performing a secondary transfer of the primary transfer image collectively to a recording medium. 4. A seamless belt for a belt constituting unit, wherein the intermediate transfer belt is the seamless belt according to claim 2 or 3, and the coefficient of friction of the surface of the electrophotographic seamless belt is the surface of the image carrier. A seamless belt for belt components characterized by a coefficient of friction greater than that. A belt component that sequentially superimposes a plurality of color toner developed images sequentially formed on an image carrier on an intermediate transfer belt for primary transfer, and collectively transfers the primary transfer image to a recording medium. 6. An electrophotographic apparatus according to claim 2, wherein the intermediate transfer belt is the seamless belt according to any one of claims 2 to 5. A belt component that sequentially superimposes a plurality of color toner developed images sequentially formed on an image carrier on an intermediate transfer belt for primary transfer, and collectively transfers the primary transfer image to a recording medium. 6. The electrophotographic apparatus according to claim 1, wherein the intermediate transfer belt is a seamless belt according to any one of claims 2 to 5, and a surface friction coefficient is larger than an image carrier surface friction coefficient. .

Images