JP2008307804A - Seamless belt for electrophotograph and its manufacturing method, intermediate transfer belt using seamless belt, and electrophotographic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seamless belt for electrophotograph (in particular, an intermediate transfer belt for full color) controlling surface properties and preventing an abnormal image such as worm-hole from occurring and, thereby, permitting formation of a high-quality image, by using the environmentally-friendly and excellently-productive manufacturing method, and to provide an electrophotographic apparatus using the seamless belt for electrophotograph. <P>SOLUTION: For example, a seamless belt base material including carbon black (filler) and (polyimide) resin is formed using a centrifugal molding method, the belt base material is brought into contact with supercritical carbon dioxide in which a low molecular compound is dissolved in an injection tank 4 and the low molecular compound is injected into the belt base material to prepare a seamless belt, whereby the contact angle with respect to water on the belt surface is controlled into 90° or more. The obtained seamless belt is used as a belt composition part which is provided to the electrophotographic apparatus. <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, and more specifically, a seamless belt capable of forming a high-quality image with controlled surface properties and no occurrence of abnormal images such as worms, environment, The present invention relates to a production method of a seamless belt in consideration of productivity and an electrophotographic apparatus using the seamless belt.

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 method (hereinafter sometimes referred to as “the present method”). 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 in which color developing devices for each color are arranged in series so as to face the intermediate transfer belt, that is, a so-called tandem system is mainly used.
The intermediate transfer belt base material used in the process of this method is required to have a high strength that can withstand repeated use without causing color misregistration due to belt deformation during running, and also requires flame retardancy. For this reason, polyimide resin and polyamideimide are preferably used. Also, there are a laminate structure based on a polyimide resin for the purpose of improving surface characteristics and a laminate structure of an elastic layer such as rubber or elastomer.

  In any configuration, the intermediate transfer belt forms a toner image on the surface thereof, and transfers (transfers) the toner image to a transfer material such as paper, so that the belt surface has releasability from the toner. It is required to be excellent. 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. As a method that does not produce such a worm-eaten image, it has been proposed to define the wettability of the surface.

For example, in Patent Document 1, the chargeability with toner is set to an appropriate charge train, and the contact angle with water is defined. Moreover, in patent document 2 or 3, the coating layer is provided on the polyimide base material and the contact angle is prescribed | regulated.
Furthermore, Patent Document 4 or 5 proposes that the contact angle be set to a specified value by including fluorine particles in polyimide.

However, since all of the proposals in Patent Documents 1 to 3 have a belt configuration in which a surface layer is provided, there is a problem in that productivity is low and cost is high, and defects due to interlayer adhesion occur.
On the other hand, in the proposal of Patent Document 4 or 5, that is, the method of directly dispersing the fluorine particles in the polyimide can achieve the specified value in the contact angle, but the dispersibility of the fluorine particles is not good. There was a problem that the dispersibility of the carbon black used for the adjustment was impaired, and the carbon black was easily worn and not durable. In addition, when polyimide is used, since its production is performed at a high temperature, there is a limitation in selecting a material for fluorine particles that can be used from the viewpoint of heat resistance.

JP-A-9-230714 No. 3613306 JP 2001-242725 A JP-A-11-231684 JP 2004-157221 A

  The present invention has been made in view of the above-described conventional technology, and surface properties such as wettability are controlled by a manufacturing method that is environmentally friendly and has good productivity, and abnormal images such as voids (worm-eaten) can be obtained. It is an object of the present invention to provide an electrophotographic seamless belt, particularly a full-color intermediate transfer belt, which is free from occurrence and capable of forming a high quality image, and an electrophotographic apparatus using the electrophotographic seamless belt. In addition, 90 degrees (degrees) or more is achieved as the wettability (surface contact angle with respect to water) in the surface properties of the seamless belt.

  As a result of intensive studies, the present inventors have found that a seamless belt base material (for example, for an intermediate transfer belt) composed of a resin containing a filler (for example, a polyimide resin) is supercritical in which a low molecular weight compound is dissolved. It has been found that by contacting with carbon dioxide or subcritical carbon dioxide, a low-molecular compound is injected into the belt substrate, and the above object can be effectively realized. That is, the inventors have found that the above problems can be solved by the inventions described in the following [1] to [12], and have reached the present invention. Hereinafter, the present invention will be specifically described.

[1]: The above-mentioned problem is a method for producing a seamless belt for electrophotography containing at least a filler, a resin, and a low-molecular compound, and a contact angle with respect to water on the surface of the seamless belt is 90 degrees or more, and ,
A seamless belt base material forming step containing at least a filler and a resin, and a supercritical fluid treatment step of bringing the belt base material into contact with supercritical carbon dioxide or subcritical carbon dioxide in which a low molecular compound is dissolved, and The low molecular weight compound is injected into the belt base material by the above-described method.

  [2]: The method for producing a seamless belt for electrophotography according to [1] above, wherein the low molecular compound is a compound having a hydrophobic group.

  [3]: In the method for producing a seamless belt for electrophotography according to the above [2], the compound having a hydrophobic group is a compound having a long-chain aliphatic hydrocarbon group, a compound having a fluorohydrocarbon group, and It is at least one compound selected from compounds having a hydrocarbon-substituted siloxy group.

  According to the above [2] and [3], the compound having a hydrophobic group can be easily injected into the belt base material via supercritical carbon dioxide or subcritical carbon dioxide, and the surface of the seamless belt can be reliably contacted with water. The angle is controlled to 90 degrees or more. As a result, it is possible to manufacture a seamless belt that is suitable for releasability with toner, prevents the occurrence of abnormal images such as insect worms, and can form high-quality images.

  [4]: The method for producing a seamless belt for electrophotography according to any one of [1] to [3] above, wherein the resin is a polyimide resin.

By using a polyimide resin, a seamless belt excellent in durability, flame retardancy, heat resistance, and mechanical properties can be produced.
[5]: In the method for producing a seamless belt for electrophotography according to any one of [1] to [4], the filler has an electric resistance adjusting function.

  By using a filler having an electrical resistance adjustment function, for example, the intermediate transfer belt can be adjusted to a predetermined electrical resistance value, and a seamless belt that can exhibit the required transfer performance can be manufactured. .

[6]: The above-mentioned problem is a seamless belt for electrophotography containing at least a filler, a resin, and a low molecular compound, and the contact angle of water on the surface of the seamless belt is 90 degrees or more, and
A process for forming a seamless belt base material in which the low molecular weight compound contains at least a filler and a resin, and a supercritical carbon dioxide or subcritical carbon dioxide in which the low molecular weight compound is dissolved in contact with the belt base material. This is solved by a seamless belt for electrophotography, which is injected into the belt base material by a critical fluid processing step.

  [7]: The electrophotographic seamless belt according to the above [6], wherein the low molecular compound is a compound having a hydrophobic group.

  [8]: The electrophotographic seamless belt according to [7], wherein the compound having a hydrophobic group is a compound having a long-chain aliphatic hydrocarbon group, a compound having a fluorohydrocarbon group, and hydrocarbon substitution It is at least one compound selected from compounds having a siloxy group.

  According to the seamless belts of the above [7] and [8], the compound having a hydrophobic group is easily injected into the belt base material via supercritical carbon dioxide or subcritical carbon dioxide, and the surface of the seamless belt is reliably ensured. Since the contact angle with respect to water is controlled to 90 ° or more, the releasability with the toner is good, the occurrence of abnormal images such as insect worms is prevented even during repeated use, and high-quality images can be formed.

  [9]: The electrophotographic seamless belt according to any one of [6] to [8], wherein the resin is a polyimide resin.

  By making a seamless belt using a polyimide resin, durability, flame retardancy, heat resistance, and mechanical properties are improved.

  [10]: The electrophotographic seamless belt according to any one of [6] to [9], wherein the filler has an electric resistance adjusting function.

  By making a seamless belt using a filler having an electric resistance adjustment function, for example, the intermediate transfer belt can be adjusted to a predetermined electric resistance value, and the required transfer performance can be exhibited, and repeated use It is possible to form a high quality image.

[11]: The above problem is that a plurality of color toner developed images sequentially formed on an image carrier are sequentially superimposed on an intermediate transfer belt to perform primary transfer, and the primary transfer images are collectively recorded on a recording medium. The intermediate transfer belt provided in an electrophotographic apparatus for secondary transfer,
The intermediate transfer belt is solved by an intermediate transfer belt, which is the electrophotographic seamless belt according to any one of [6] to [10].

[12]: The above problem is that primary transfer is performed by sequentially superimposing a plurality of color toner developed images sequentially formed on an image carrier on an intermediate transfer belt, and the primary transfer images are collectively recorded on a recording medium. An electrophotographic apparatus equipped with the intermediate transfer belt for secondary transfer,
The intermediate transfer belt is solved by an electrophotographic apparatus which is the electrophotographic seamless belt according to any one of [6] to [10].

According to the method for producing a seamless belt for electrophotography of the present invention, a supermolecular carbon dioxide or a subcritical carbon dioxide is used (supercritical fluid treatment step), and a low molecular compound is directly injected into a seamless belt substrate. There is no problem of dispersibility as in the case of the solution method, and the characteristics are not adversely affected, and the contact angle of the seamless belt surface with water can be 90 degrees or more. In addition, because of the supercritical fluid treatment process, the production efficiency can be improved, and further, the burden on the global environment can be reduced by reducing waste materials and saving resources.
According to the electrophotographic seamless belt of the present invention, the surface properties are controlled by the above production method so that the contact angle with respect to the water of the seamless belt surface is 90 degrees or more, the releasability from the toner is excellent, and the belt surface In addition, since the back surface is smooth and glossy and has a good surface property, abnormal images such as worms are not generated even when used repeatedly, and a high-quality image can be stably formed.
According to the intermediate transfer belt of the present invention, even if it is mounted on a high-speed full-color printing apparatus (for example, a tandem apparatus), it can withstand repeated use, and the belt surface is excellent in releasability from toner, so that the worm-eating image A high-quality image can be formed stably without causing abnormal images such as
According to the electrophotographic apparatus of the present invention, a high-quality image that does not generate an abnormal image such as an insect worm can be stably formed over a long period of time even in high-speed and full-color printing.

As described above, the method for producing a seamless belt for electrophotography in the present invention is a method for producing a seamless belt for electrophotography containing at least a filler, a resin, and a low-molecular compound, and the surface of the seamless belt is free from water. The contact angle is 90 degrees or more, and
A seamless belt base material forming step containing at least a filler and a resin, and a supercritical fluid treatment step of bringing the belt base material into contact with supercritical carbon dioxide or subcritical carbon dioxide in which a low molecular compound is dissolved, and The low molecular weight compound is injected into the belt base material by the method described above.

The seamless belt for electrophotography in the present invention is a seamless belt for electrophotography containing at least a filler, a resin, and a low molecular compound, and the contact angle of water on the surface of the seamless belt is 90 degrees or more. ,And,
A process for forming a seamless belt base material in which the low molecular weight compound contains at least a filler and a resin, and a supercritical carbon dioxide or subcritical carbon dioxide in which the low molecular weight compound is dissolved in contact with the belt base material. Injected into the belt base material by a critical fluid treatment step.

  That is, in the present invention, an electron including at least a filler, a resin, and a low molecular compound is formed by a seamless belt base material forming step and a supercritical fluid treatment step of injecting a low molecular compound into the belt base material. A photographic seamless belt is manufactured, and the contact angle with respect to water on the surface of the seamless belt is controlled to be 90 degrees or more. In the production method, the low molecular weight compound is directly injected into the seamless belt base material via supercritical carbon dioxide or subcritical carbon dioxide, so there is no problem of dispersibility as in the past, and the properties are adversely affected. There is nothing. In addition, it is possible to improve the production efficiency and reduce the burden on the global environment by reducing waste materials and saving resources. Details will be described below.

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.
Of these, fluorine resins and imide resins that are excellent in terms of durability and flame retardancy are particularly preferably used as intermediate transfer belt applications. Furthermore, in addition to heat resistance, a polyimide or polyamide-imide resin excellent in mechanical properties is preferably applied.

As described above, a seamless belt base material containing at least a filler and a resin (hereinafter sometimes simply referred to as “belt base material”) is a solution containing at least a filler and a resin, for example, an organic material. A solution in which a solution containing a polyimide precursor and a filler in a polar solvent is used as a coating solution, and the coating solution is applied to a cylindrical shape or the like and formed into a belt substrate having a predetermined shape is preferably used.
Hereinafter, a polyimide resin that is preferably used as a resin that is a component of the coating liquid will be described as an example.

The polyimide produced | generated by heat processing (imidation) of a polyimide precursor is demonstrated in detail.
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 (I).

(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.
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, and N, N. -Acetamide solvents such as dimethylacetamide, N, N-diethylacetamide, pyrrolidone solvents such as N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, phenol, o-, m-, or p-cresol, Phenolic solvents such as xylenol, halogenated phenol and catechol, ether solvents such as tetrahydrofuran, dioxane and dioxolane, alcoholic solvents such as methanol, ethanol and butanol, cellosolve such as butyl cellosolve or hexamethyl Phosphoramides, .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.
Below, the manufacturing method of a polyamic acid is demonstrated concretely.

  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 prepared by blending the aromatic polyvalent carboxylic acid anhydride or derivative thereof and the aromatic diamine component in an approximately equimolar ratio and performing a polymerization reaction in an organic polar solvent. A polyimide precursor solution is obtained in a state in which is uniformly dissolved in an organic polar solvent.

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 Co., Ltd.), and the like. It is mentioned as a thing.

  A coating liquid is prepared by mixing and dispersing a filler described later in a synthesized or obtained polyamic acid solution. The coating liquid is applied to a support (molding mold) as described below, and then subjected to a treatment such as heating, whereby conversion (imidation) from polyamic acid, which is a polyimide precursor, to polyimide is performed. A substrate is formed.

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. However, when the catalyst is used, imidization is accelerated at a lower temperature. It is said that the 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 commonly performed 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 such as the NMR method, the Fourier transform infrared spectroscopy (FT-IR method), the method for quantifying moisture accompanying imide ring closure, and the carboxylic acid neutralization titration method are used. -Lier transformation infrared spectroscopy (FT-IR method) is the most common method.

In the 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 ratio = [(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 (an imide ring C═O group bending vibration band) which is one of the characteristic absorptions of imide and the characteristic absorption of benzene ring of 1,015 cm ⁻¹ .
(2) Absorbance ratio between 1,380 cm ⁻¹ (inflection 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 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 the characteristic absorptions of imide, and 1,670 cm ⁻¹ (interaction between amide group N—H bending vibration and C—N stretching vibration) Absorbance ratio.
In addition, if it is confirmed that the amide group-derived multiple absorption band from 3000 to 3300 cm ⁻¹ has disappeared, 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 used for forming the belt base material in 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, an electric resistance adjusting material having an electric resistance adjusting function (hereinafter abbreviated as a resistance adjusting agent) 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 metal oxide fine 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. Alternatively, 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 dispersing aid as needed. Furthermore, the surface functional group of carbon black and an organic compound having reactivity with the functional group may be surface-treated.

Next, the process (seamless belt base material formation process) which manufactures a seamless belt base material using the coating liquid containing the said polyimide precursor is demonstrated.
When this step is further subdivided, a step of dispersing a resistance adjuster in the coating solution as necessary, a step of applying and casting the coating solution prepared in this step on a support (molding mold), The step of removing the solvent in the coating film coated and cast on the support by heating, the step of heating and promoting the imidation of the precursor contained in the coating film, and the formed thin film from the support It consists of a step of releasing, and a step of using the released thin film as a seamless belt base material.
It is manufactured by.

  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 it with the polyimide precursor solution. Here, a method of dispersing carbon black as a resistance control agent will be described as an example. In addition, the following is an example and it 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, a process of applying and casting the prepared coating solution on a support (molding die) will be described. First, the case where a mold by centrifugal molding (centrifugal mold) is used as the support will be described as an example. The following description is an example and the conditions are not limited thereto.
The centrifugal mold is composed of a cylindrical rotating body. While this cylindrical rotating body is slowly rotated, the coating liquid is applied and cast on the inner surface of the cylinder so as to be uniform throughout. To form a coating film. Thereafter, the rotation speed is increased to a predetermined speed, and when the predetermined speed is reached, the rotation is continued for a desired time while maintaining the constant speed. 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 the self-supporting film is formed, it is returned to room temperature, transferred to a heating furnace (baking furnace) capable of high-temperature processing together with the support, and subjected to high-temperature heat treatment (baking) of about 250 ° C. to 400 ° C. The polyimide precursor is imidized. After the imidization is completed, the thin film is peeled off from the mold by slow cooling. In this way, a seamless belt base material is formed. In addition, it is preferable to form a mold release agent or a mold release layer on the mold so that the thin film can be easily peeled off.

The contact angle (wetability) with respect to water, which is a surface energy index, in the seamless belt base material made of polyimide resin thus produced is generally about 60 to 80 degrees and cannot be said to be a high value. In this state, 90 degrees or more, which is a problem in the present invention, cannot be satisfied.
Therefore, when the seamless belt base material is used as it is, 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 seamless belt base material with a hydrophobic resin such as a fluororesin, but this is also not preferable because of high cost.
In addition, it may be possible to contain a fluorine-based or silicon-based resin or a fluorosurfactant, but because of its poor affinity with the polyimide resin, it can be contained in a very small amount or thermally decomposed due to the high temperature during polyimide drying. However, the effect may not be obtained. 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 are likely to be unevenly distributed on the air surface of the thin film formed on the cylindrical inner surface during drying. That is, it is unevenly distributed in a portion corresponding to the back surface when used as a transfer belt, and the surface property cannot be improved.
For this reason, it is necessary to adopt a method of applying the material to the outer periphery of the cylindrical shape instead of using the cylindrical inner surface as in the case of centrifugal molding, which makes the molding difficult.

In the present invention, the formed belt base material containing at least the filler and the resin is subjected to a supercritical fluid treatment step, so-called supercritical carbon dioxide or subcritical carbon dioxide (supercritical carbon dioxide field or subcritical carbon dioxide). By using a critical carbon dioxide field, the low molecular weight compound is injected into the belt substrate effectively and efficiently, and the contact angle of the seamless belt surface with water is 90 degrees or more.
Next, the process (supercritical fluid process) of the seamless belt produced as described above with supercritical carbon dioxide will be described.

  By placing the seamless belt base material in a supercritical carbon dioxide field in which a specific low molecular weight compound is dissolved, and adjusting the type, pressure, and temperature conditions of the fluid, supercritical carbon dioxide is contained in the belt base material. Alternatively, a low molecular compound dissolved in subcritical carbon dioxide can be injected.

Among the supercritical fluids, carbon dioxide having a critical temperature close to room temperature is preferable. 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 base material is appropriately controlled depending on the amount dissolved in supercritical carbon dioxide or subcritical carbon dioxide, pressure, temperature, contact time (flow rate), and the like. In addition to the supercritical carbon dioxide or subcritical carbon dioxide, other liquids (entrainers) can be used in combination as needed in order to improve the solubility and injectability of the low molecular weight compound.

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, an apparatus as shown in the schematic block diagram of FIG. 1 is used.
As shown in FIG. 1, as shown in FIG. 1, a pressure-resistant container (injection tank) 4 for performing supercritical fluid processing, and a pressure pump (high-pressure liquid feed pump) 1 for supplying supercritical carbon dioxide or subcritical carbon dioxide. And a separation tank 9 for separating a gas containing the extracted residue into an extract and a gas after depressurization by the decompression valve 7.
In FIG. 1, reference numeral 2 is a stop valve, 3 is a filter, 5 is a stirrer, 6 is a filter, 7 is a pressure reducing valve, 8 is a flow meter, T is a thermometer, and P is a pressure gauge.

As a treatment method using the above apparatus, first, a low-molecular compound that can be dissolved in supercritical carbon dioxide or subcritical carbon dioxide is charged into the pressure-resistant container. Next, the supercritical carbon dioxide is supplied into the pressure vessel by a pressure pump, the low molecular compound is dissolved in supercritical carbon dioxide or subcritical carbon dioxide, and this is brought into contact with the belt base material. Is injected into the belt substrate.
At this time, the supercritical fluid treatment is carried out by selecting the conditions under which the low molecular weight compound is effectively injected into the seamless belt within the above-mentioned range of pressure and temperature conditions. The supercritical carbon dioxide or subcritical carbon dioxide is returned to normal temperature and normal pressure, and a seamless belt containing a filler, a resin, and a low molecular compound is taken out from the pressure vessel.

  According to the above method, the low molecular compound can be effectively injected into the belt base material. By appropriately selecting this low molecular weight compound, particularly a compound having a hydrophobic group, it is possible to make the contact angle of water on the surface of the seamless belt, particularly the polyimide seamless belt, 90 ° or more. In addition, this supercritical fluid treatment is more effective because the treatment is performed not only from the front surface of the belt but also from the back surface.

The low molecular weight compound is preferably a compound that prevents hygroscopic expansion. As a low molecular weight compound for preventing such hygroscopic expansion, a compound having a number average molecular weight of 10,000 or less, which dissolves in supercritical carbon dioxide or subcritical carbon dioxide and penetrates into polyimide, may be used. The compound having a contact angle of 90 ° or more is preferably a compound having a hydrophobic group (hereinafter sometimes referred to as “hydrophobic group”).
Specific examples of the compound having a hydrophobic group include compounds having a long-chain aliphatic hydrocarbon group, a fluorine group, and a siloxane group, that is, a compound having a long-chain aliphatic hydrocarbon group, and a fluorohydrocarbon group. It is preferably at least one compound selected from a compound and a compound having a hydrocarbon-substituted siloxy group.

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

Examples of the synthetic wax include synthetic hydrocarbon waxes such as Fischer-Tropsch wax, polyethylene wax, and polypropylene wax.
Examples of the modified wax include mineral waxes such as montan wax derivatives, paraffin wax derivatives, microcristan wax derivatives, and modified products of petroleum wax, hardened castor oil, 12-hydroxystearic acid, 12-hydroxystearic acid derivatives, fatty acids. Examples include amides, fatty acid monohydric alcohol esters, fatty acid high alcohol esters, fatty acid amines, modified products of animal fats such as waxy dialkyl ketones, and the like.
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 compound having a hydrocarbon-substituted siloxy group (silicon compound) include silicone oil, modified silicone oil, silicone surfactant, silicone wax, silicone resin, and silicone rubber. In addition, a derivative having a polydimethylsiloxane group can be used.
Examples of the compound having a fluorohydrocarbon group (fluorine-based compound) include a fluorine-based surfactant, a fluorine resin, a fluorine rubber, and a fluorine-modified compound.
Further, a compound having both functional groups such as a fluorinated silicon resin may be used.

At least one selected from the above-mentioned long-chain aliphatic hydrocarbon group-containing compounds, silicon compounds, and fluorine compounds is dissolved in supercritical carbon dioxide or subcritical carbon dioxide, and contains at least a filler and a resin. The seamless belt base material to be brought into contact (supercritical fluid treatment step) is poured into the polyimide resin and fixed.
For example, a compound that is too low in molecular weight and liquid is preferably a compound that is 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 foregoing, the seamless belt of the present invention has been described with respect to a single layer configuration containing a filler, a resin, and a low molecular compound, but is not limited thereto, and a seamless belt having a single layer configuration (for example, The production method of the present invention can be similarly applied to a structure in which a plurality of layers of various resins, rubbers, and elastomers are laminated on a base material (seamless belt using a polyimide resin).
That is, according to the supercritical fluid processing method of the present invention, the contact angle with respect to water on the surface can be 90 ° or more for a wide range of material configurations, which is very versatile and effective. It can be applied as a means.

The seamless belt of the present invention is particularly suitably used as an intermediate transfer belt. Such a seamless belt, for example, sequentially superimposes a plurality of color toner developed images sequentially formed on an image carrier on the intermediate transfer belt. The belt component is used in an electrophotographic apparatus that performs primary transfer and performs secondary transfer of the primary transfer image collectively onto a recording medium.
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 the schematic diagram of the relevant part. The schematic diagram is an example, and the present invention is not limited to this.

The schematic diagram of FIG. 2 shows a schematic configuration of the main part of an electrophotographic apparatus equipped with a belt component and the like.
An intermediate transfer unit 500 that is a belt component shown in FIG. 2 includes an intermediate transfer belt 501 that is an intermediate transfer member stretched around a plurality of rollers. Around the intermediate transfer belt 501, a secondary transfer bias roller 605 that is a secondary transfer charge applying unit of the secondary transfer unit 600, a belt cleaning blade 504 that is an intermediate transfer member cleaning unit, and a lubricant for a lubricant application unit. A lubricant application brush 505 or the like that is an application member is disposed so as to face each other.

  A position detection mark (not shown) is provided on the outer peripheral surface or the 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. A position detection mark may be provided on the inner peripheral surface side of the intermediate transfer belt 501. An 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 where the intermediate transfer belt 501 is bridged.

  The intermediate transfer belt 501 includes a primary transfer bias roller 507 serving as a primary transfer charge applying unit, a belt driving roller 508, a belt tension roller 509, a secondary transfer counter roller 510, a cleaning counter roller 511, and a feedback current detection roller 512. It is stretched around. Each roller is formed of a conductive material, and each roller other than the primary transfer bias roller 507 is grounded. The primary transfer bias roller 507 is applied with a transfer bias controlled to a predetermined current or voltage according to the number of superimposed toner images by a primary transfer power source 801 controlled at a constant current or voltage. ing.

The intermediate transfer belt 501 is driven in the arrow direction by a belt driving roller 508 that is driven to rotate in the arrow direction by a drive motor (not shown).
The intermediate transfer belt 501 as a belt component is usually a semiconductor or an insulator and has a single-layer or multi-layer structure, but the seamless belt of the present invention is preferably used, thereby improving durability. Excellent image formation can be realized. Further, 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 serving as a secondary transfer unit is attached to and separated from a belt outer peripheral surface of the intermediate transfer belt 501 in a portion stretched around the secondary transfer counter roller 510 by a contact / separation mechanism, which will be described later. It is configured to be able to contact and separate. The secondary transfer bias roller 605 is disposed so as to sandwich the transfer paper P, which is a recording medium, between the portion of the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510 and a constant current. A transfer bias having a predetermined current is applied by a secondary transfer power source 802 to be controlled.

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

  In the color copying machine having such a configuration, when an image forming cycle is started, the photosensitive drum 200 is rotated in a counterclockwise direction indicated by an arrow by a drive motor (not shown), and 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, the respective 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. 2, 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 uniformly charged, 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 does not adhere to the remaining portion of the photosensitive drum 200, and the charge is not charged. The toner is attracted to the nonexposed portion, that is, the 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 manner is primarily transferred onto the belt outer peripheral surface of the intermediate transfer belt 501 that is rotating at a constant speed while being in contact with the photosensitive drum 200. 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. On the photosensitive drum 200 side, the process proceeds to the Y image forming process after the Bk image forming process, and reading of the Y image data by the color scanner starts at a predetermined timing, and the photosensitive drum is written by laser beam writing with the Y image data. A Y electrostatic latent image is formed on the surface of 200.

Then, after the rear end portion of the previous Bk electrostatic latent image passes and before the front end portion of the T electrostatic latent image reaches, the revolver developing unit 230 is rotated, and the Y developing device 231Y develops. The Y electrostatic latent image is developed with Y toner. Thereafter, the development of the Y electrostatic latent image area is continued. When the trailing edge of the Y electrostatic latent image passes, the revolver developing unit is rotated in the same manner as in the case of the previous Bk developing machine 231K, and the next The 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 way 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.

  When the leading edge of the toner image on the intermediate transfer belt 501 reaches the secondary transfer portion where the nip is formed by the intermediate transfer belt 501 stretched around the secondary transfer counter roller 510 and the secondary transfer bias roller 605. Then, 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 the transfer paper P is conveyed along the transfer paper guide plate 601, and the transfer paper P and the toner image are transferred. Resist alignment is performed.

  In this way, when the transfer paper P passes through the secondary transfer portion, the four-color superimposed toner image on the intermediate transfer belt 501 is transferred by the transfer bias applied by the secondary transfer power source 802 to the secondary transfer bias roller 605. Are collectively transferred (secondary transfer) onto the transfer paper P.

  After the transfer paper P is conveyed along the transfer paper guide plate 601 and passed through a portion facing the transfer paper neutralization charger 606 composed of a static elimination needle disposed on the downstream side of the secondary transfer portion, the transfer paper P is discharged. Then, it is sent toward the fixing device 270 by the belt conveying device 210 which is a belt component (see FIG. 2). Then, after the toner image is melted and fixed at the nip portions 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), and is stacked face up on a copy tray (not shown). Is done. 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. Further, 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 be brought into contact with and separated from the belt outer peripheral surface of the intermediate transfer belt 501 at a predetermined timing 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 movement direction of the intermediate transfer belt 501. The toner seal member 503 receives the falling toner dropped from the belt cleaning blade 504 when cleaning the residual toner, and prevents the falling toner from scattering on the transfer path of the transfer paper P. 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 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) that is 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 contact with and separated from the belt outer peripheral surface of the intermediate transfer belt 501 at a predetermined timing by respective contact and separation mechanisms (not shown). .

  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 first color (M) image formation process of the first sheet and the first color of the second sheet. The process proceeds to the image forming process (Bk). Further, the intermediate transfer belt 501 has a second Bk toner 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 image is first 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 the number of times. In the case of the single color copy mode, only the predetermined color developing machine 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 kept in contact with the intermediate transfer belt 501. The copy operation is performed in the state.

In the above-described embodiment, the copying machine including only one photosensitive drum 1 has been described. However, the present invention may be configured such that, for example, a plurality of photosensitive drums as illustrated in FIG. 3 are arranged in parallel along one intermediate transfer belt. The present invention can also be applied to the image forming apparatus.
FIG. 3 shows a configuration of a four-drum digital color printer including four photosensitive drums 21BK, 21Y, 21M, and 21C for forming toner images of four different colors (black, yellow, magenta, and cyan). An example is shown.

  In FIG. 3, 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 performs image processing to convert the signal into black (BK), magenta (M), yellow (Y), and cyan (C) color signals for image formation, and transmits the signals to the image writing unit 12. To do. 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 image carriers (photoconductors) 21BK, 21M, 21Y, and 21C that have a writing optical path and are provided for each color of the image forming unit 913.

The image forming unit 13 includes photoconductors 21BK, 21M, 21Y, and 21C that are image carriers for black (BK), magenta (M), yellow (Y), and cyan (C). As each photoconductor for each color, an OPC photoconductor is usually used. Around the photoreceptors 21BK, 21M, 21Y, and 21C, there are a charging device, an exposure unit for laser light from the writing unit 12, and developing devices 20BK, 20M, 20Y for black, magenta, yellow, and cyan, respectively. 20C, primary transfer bias rollers 23BK, 23M, 23Y, and 23C as primary transfer means, a cleaning device (not shown), and a photosensitive member static elimination device (not shown) are arranged.
The developing devices 20BK, 20M, 20Y, and 20C use a two-component magnetic brush developing system. The intermediate transfer belt 22, which is a belt component, is interposed between the photosensitive members 21BK, 21M, 21Y, and 21C and the primary transfer bias rollers 23BK, 23M, 23Y, and 23C, and is formed on the photosensitive members. The toner images of each color are sequentially superimposed and transferred.

  On the other hand, the transfer paper P is fed from the paper feed unit 14 and then carried by the transfer conveyance belt 50, which is a belt component, via the registration roller 16. When the intermediate transfer belt 22 and the transfer conveyance belt 50 come into contact, the toner image transferred onto the intermediate transfer belt 22 is subjected to secondary transfer (collective transfer) by a secondary transfer bias roller 60 as a secondary transfer unit. )

  As a result, 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, and after the image transferred by the fixing device 15 is fixed, it is discharged out of the printer main body.

The residual toner that is not transferred during the secondary transfer and remains on the intermediate transfer belt 22 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 in constant 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 suitably applied to an intermediate transfer belt type image forming apparatus equipped with the intermediate transfer belt 501 or 22 as described above, and a transfer conveyance belt instead of the intermediate transfer belt 501 or 22. The present invention can also be applied to a transfer / conveying belt type image forming apparatus equipped with the above. 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, as shown in the schematic diagram of FIG. 4, an image in which a part of the image is missing (a void), that is, a so-called worm-eaten image is obtained.
However, in the present invention, this can be prevented by making the contact angle of the belt surface with water 90 ° or more by the above-mentioned means.

  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
A coating liquid (coating liquid) is prepared by the following procedure, and a seamless belt base material is produced and supercritical fluid treatment of the seamless belt base material (hereinafter referred to as “supercritical carbon dioxide treatment”) is used. An intermediate transfer belt was manufactured by sequentially performing the steps.
[Preparation of coating solution]
First, the following constituent materials (compositions) were mixed and dispersed using a zirconia bead of φ1 mm for 5 hours with a bead mill disperser to prepare a carbon dispersion.
<Composition of carbon dispersion>
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

Next, using the carbon dispersion, the following constituent materials (compositions) were mixed, mixed and defoamed with a centrifugal stirring deaerator to obtain a coating solution.
<Composition of coating solution>
Carbon black dispersion liquid: 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 parts by weight

[Preparation of seamless belt substrate]
Next, a metal cylinder having an inner diameter of 100 mm and a length of 300 mm with 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. When the coating has spread evenly after the predetermined amount has been flown, the number of revolutions is increased to 500 rpm, the hot air circulating dryer is introduced, and the temperature is raised to 100 ° C. at a temperature rising rate of 5 ° C./min. Heated for minutes. 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 heat-treated (firing) for 60 minutes.
After stopping 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 substrate having a film thickness of 70 μm.

[Supercritical carbon dioxide treatment of seamless belt substrate]
The prepared seamless belt base material and low molecular weight compound [Modiper F600: Fluorine graft polymer manufactured by NOF Corporation] 0.7 g are put into the pressure cell of the pressure vessel (injection tank) 4 (internal volume 700 ml) of the apparatus shown in FIG. After that, the pressure cell was sealed.

  Next, carbon dioxide is supplied to the pressure cell by a supply cylinder, adjusted to 30 MPa and 40 ° C. by the pressure pump (high pressure liquid feed pump) 1 and the temperature adjusting means, and after the temperature and pressure are stabilized, the pressure cell is sealed. It was 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. The obtained seamless belt had glossy, smooth and good surface properties on both the belt surface and the back surface.

(Example 2)
A seamless belt described in the present invention was obtained in the same manner as in Example 1 except that the low molecular weight compound used in the supercritical carbon dioxide treatment in Example 1 was changed to the following. The obtained seamless belt had good glossy surface properties on both the belt surface and the back surface.
Low molecular weight compound: Megafac F493 (Fluorine surfactant manufactured by Dainippon Ink and Chemicals)

(Example 3)
A seamless belt described in the present invention was obtained in the same manner as in Example 1 except that the low molecular weight compound used in the supercritical carbon dioxide treatment in Example 1 was changed to the following. The obtained seamless belt had good glossy surface properties on both the belt surface and the back surface.
Low molecular compound: HNP-51 (Nippon Seiwa Co., Ltd. paraffin wax)

Example 4
A seamless belt described in the present invention was obtained in the same manner as in Example 1 except that the low molecular weight compound used in the supercritical carbon dioxide treatment in Example 1 was changed to the following. The obtained seamless belt had good glossy surface properties on both the belt surface and the back surface.
Low molecular weight compound: AMS-C30Wax (silicone wax manufactured by Toray Dow Corning)

(Comparative Example 1)
A seamless belt described in the present invention was obtained in the same manner as in Example 1 except that the supercritical carbon dioxide treatment in Example 1 was not performed. The obtained seamless belt had good glossy surface properties on both the belt surface and the back surface.

(Comparative Example 2)
A coating liquid (coating liquid) was prepared by the following procedure, and an intermediate transfer belt was produced using this coating liquid.
[Preparation of coating solution]
First, the following constituent materials (compositions) were mixed and dispersed using a zirconia bead of φ1 mm for 5 hours with a bead mill disperser to prepare a carbon dispersion.
<Composition of carbon dispersion>
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 dispersion, the following constituent materials (compositions) were mixed, mixed and defoamed with a centrifugal stirring deaerator to obtain a coating solution.
<Composition of coating solution>
Carbon black dispersion liquid: 50 parts by weight Polyimide solution U-varnish A (Ube Industries; solid content 18 wt%): 50 parts by weight Modiper F600 (manufactured by NOF Corporation): 5 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 obtained seamless belt had a glossy state in which the belt back surface was clouded.

(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 obtained seamless belt was in a dull state where the belt surface was clouded.

  About each seamless belt produced in the said Examples 1-4 and Comparative Examples 1-3, the contact angle with respect to the water of a belt surface was measured using the CA-W type | mold contact angle measuring apparatus (made by Kyowa Interface Science Co., Ltd.). The results are shown in Table 1 below.

Also, each seamless belt produced in Examples 1 to 4 and Comparative Examples 1 to 3 is mounted as an intermediate transfer belt of the electrophotographic apparatus shown in FIG. 3, and the worm-eaten in the initial image and the full-color image after printing 10,000 sheets. Images were evaluated according to the following ranks. The results are shown in Table 1 below.
Rank 3; no worm-eaten image Rank 2; there are several worm-eaten images.
Rank 1: A large number of worm-eaten images can be seen.

As shown in Table 1 above, in the present invention, a low molecular weight compound can be injected with high productivity even into a resin such as a polyimide resin, and the contact angle of the belt surface with water can be easily controlled by controlling the physical properties of the belt surface. Can be 90 degrees or more. Moreover, even after printing a large number of sheets by a full-color electrophotographic apparatus (after printing 10,000 sheets), no worm-eaten image is generated at rank 3, and a good image can be stably provided over a long period of time.
On the other hand, in the comparative examples to which the supercritical fluid processing in the present invention is not applied, the worm-eaten image rank in the full-color image after printing 10,000 sheets is 1, and the difference from the present invention is clear.

It is a schematic block diagram which shows an example of the apparatus used in order to inject | pour a low molecular compound through a supercritical carbon dioxide or a subcritical carbon dioxide into the belt base material in this invention. 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 for demonstrating the abnormal image (worm-eaten) which is one of the solution subjects in this invention.

Explanation of symbols

(Figure 1)
DESCRIPTION OF SYMBOLS 1 High pressure liquid feed pump 2 Stop valve 3 Filter 4 Extraction tank 5 Stirrer 6 Filter 7 Pressure reducing valve 8 Flow meter 9 Separation tank 10 Extract 11 Extract gas T Thermometer P Pressure gauge (FIG. 2)
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. 3)
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. 4)
41 color image part 42 worm-eaten part

Claims (12)

A method for producing an electrophotographic seamless belt comprising at least a filler, a resin, and a low molecular compound, wherein the contact angle of the surface of the seamless belt with respect to water is 90 degrees or more, and
A seamless belt base material forming step containing at least a filler and a resin, and a supercritical fluid treatment step of bringing the belt base material into contact with supercritical carbon dioxide or subcritical carbon dioxide in which a low molecular compound is dissolved, and A method for producing a seamless belt for electrophotography, wherein the low molecular compound is injected into the belt base material by the method described above.   The method for producing a seamless belt for electrophotography according to claim 1, wherein the low molecular compound is a compound having a hydrophobic group.   The hydrophobic group-containing compound is at least one compound selected from a compound having a long-chain aliphatic hydrocarbon group, a compound having a fluorohydrocarbon group, and a compound having a hydrocarbon-substituted siloxy group. A method for producing a seamless belt for electrophotography according to claim 2.   The said resin is a polyimide resin, The manufacturing method of the seamless belt for electrophotography in any one of Claims 1-3 characterized by the above-mentioned.   The method for producing a seamless belt for electrophotography according to any one of claims 1 to 4, wherein the filler has an electric resistance adjusting function. A seamless belt for electrophotography comprising at least a filler, a resin, and a low molecular compound, wherein a contact angle of water on the surface of the seamless belt with respect to water is 90 degrees or more, and
A process for forming a seamless belt base material in which the low molecular weight compound contains at least a filler and a resin, and a supercritical carbon dioxide or subcritical carbon dioxide in which the low molecular weight compound is dissolved in contact with the belt base material. A seamless belt for electrophotography, which is injected into the belt base material by a critical fluid treatment step.   The electrophotographic seamless belt according to claim 6, wherein the low-molecular compound is a compound having a hydrophobic group.   The compound having a hydrophobic group is at least one compound selected from a compound having a long-chain aliphatic hydrocarbon group, a compound having a fluorohydrocarbon group, and a compound having a hydrocarbon-substituted siloxy group. The seamless belt for electrophotography according to claim 7.   The electrophotographic seamless belt according to claim 6, wherein the resin is a polyimide resin.   The seamless belt for electrophotography according to any one of claims 6 to 9, wherein the filler has an electric resistance adjusting function. An electrophotographic apparatus for performing 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 secondary transfer of the primary transfer image collectively to a recording medium The intermediate transfer belt equipped,
The intermediate transfer belt is an electrophotographic seamless belt according to any one of claims 6 to 10. The intermediate transfer belt 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 An electrophotographic apparatus equipped with
The electrophotographic apparatus according to claim 6, wherein the intermediate transfer belt is an electrophotographic seamless belt according to claim 6.

Images