JP2011059545A - Method for manufacturing intermediate transfer body, and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an intermediate transfer body having a desired resistance value with high uniformity thereof by stabilizing the addition amount of carbon. <P>SOLUTION: The method for manufacturing an intermediate transfer body includes steps of: preparing a dispersion containing at least carbon black, resin, and a solvent; preparing a coating liquid with an adjusted carbon black content by use of the dispersant; applying the coating liquid to the inner surface or outer surface of a mold, followed by drying or curing to thereby form a film; and demolding the film. In the dispersant, volume average particle size Mv1 of carbon black after dispersion of the carbon black is between 150 nm and 300 nm, volume average particle size Mv2 of carbon black after heating in a sealed container for 24 hours under 60&deg;C-atmosphere is between 100 nm and 200 nm, and the ratio of the Mv2 to the Mv1 (Mv2/Mv1) satisfies 0.33 or more and less than 1. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

The present invention relates to a seamless belt provided in an image forming apparatus such as a copy printer and the like, and an image forming apparatus using the same, and more particularly to an intermediate transfer belt suitable for full-color image formation and an image forming apparatus using the same.

Conventionally, seamless belts have been used in various applications in electrophotographic apparatuses. Particularly in recent full-color electrophotographic apparatuses, an intermediate transfer belt that temporarily superimposes developed images of four colors of yellow, magenta, cyan, and black on an intermediate transfer medium and then collectively transfers them onto a transfer medium such as paper. The method is used.

In the intermediate transfer belt system, there is a system that uses four color developing devices for one photoconductor, but this system has a drawback that the printing speed is slow. As a method capable of high-speed printing, there is a four-tandem tandem method in which photoconductors are arranged for four colors and each color is continuously transferred to paper. However, in this method, there are fluctuations due to the environment of the paper, etc., and it is very difficult to match the position accuracy of overlapping each color image, causing a color misregistration image. Therefore, in recent years, it has become the mainstream to adopt the intermediate transfer method for the quadruple tandem method.

For this reason, it has become necessary for the intermediate transfer belt to satisfy characteristics corresponding to requirements such as high speed and positional accuracy. In particular, for positional accuracy, it is required to suppress fluctuation due to deformation such as elongation of the belt itself due to continuous use. Further, since the intermediate transfer belt is laid out over a wide area of the apparatus and a high voltage for transfer is applied, flame retardancy is also required. Accordingly, polyimide resins, polyamideimide resins, and the like that are high elastic modulus and high heat resistance resins are mainly used.

In addition, in the intermediate transfer belt system, an image of charged toner is transferred by the action of an electric field, so that the resistance value needs to be adjusted to a certain value. The resistance value is generally adjusted to a surface resistance value of about 1 × 10 7 to 1 × 10 13 Ω / □ and a volume resistance value of about 1 × 10 5 to 1 × 10 12 Ωcm.

Such a resistance value is adjusted by dispersing organic or inorganic conductive fine particles or by containing a material such as a conductive polymer or an ionic conductive agent in the resin. Among these, carbon black is most preferably used.

When a polyimide resin or a polyamideimide resin is used as the resin for the intermediate transfer belt, carbon black is particularly preferably used. Polyimide resins and polyamideimide resins are formed by heat-curing a resin solution dissolved in a polar solvent. The polar solvent used for this, particularly N-methyl-2-pyrrolidone, preferably acts on the dispersibility of carbon black. Therefore, it is preferably used.

In order to disperse carbon black in a polyimide resin or a polyamideimide resin, carbon is dispersed in a fine particle state having a desired particle diameter in a solvent using a general-purpose disperser such as a bead mill, a ball mill, a paint shaker, or a planetary ball mill. Then, using the resin solution in which carbon is dispersed, a uniform intermediate transfer belt having a desired resistance value and no variation is manufactured. In order to obtain a preferable electrical characteristic as an intermediate transfer belt, the following proposals have been made.
Patent Documents 1 to 4 propose a method capable of realizing suitable dispersion in a polyimide resin by using a carbon black surface treatment or a dispersant. In Patent Document 5, a method of synthesizing polyamic acid in an insulating fine particle dispersion, that is, a polyamic acid solution obtained by reacting a diamine compound and an acid anhydride compound in an organic polar solvent in which insulating fine particles are dispersed in advance. A method of preparing is proposed. In Patent Document 6, it is proposed to regulate the particle size variation when the carbon black dispersion is changed to the coating solution.

However, in production, defective products are generated due to fluctuations in the amount and variation of carbon in the belt to obtain the desired resistance value depending on the production process lot and lots of materials such as carbon black and resin. In addition, the above-described conventional technique has a problem that the production efficiency is lowered because the defective product cannot be discriminated unless it is once formed into a coating film.

The present invention uses an intermediate transfer body having a desired resistance value and high uniformity with a stable carbon addition amount, and the intermediate transfer body, regardless of the production process lot or the lot of materials such as carbon black and resin. An object of the present invention is to provide an intermediate transfer type image forming apparatus particularly suitable for full color image formation.

As a result of intensive studies, the inventors of the present invention, in the manufacture of a polyimide resin or polyamide-imide resin seamless belt in which carbon black is dispersed, first, carbon black is dispersed in a solution containing at least a resin and a solvent, And a manufacturing process for preparing a coating liquid in which a desired carbon black content is adjusted by mixing and stirring the dispersion and the resin solution.
In the carbon black dispersion, the volume average particle diameter Mv1 of carbon black is 150 nm or more and 300 nm or less, and the volume average particle diameter Mv2 of carbon black after being heated in a sealed container at 60 ° C. for 24 hours. It was found that the above problem can be solved by using a dispersion liquid in which the ratio of Mv2 to Mv1 (Mv2 / Mv1) is 0.33 or more and less than 1 in the range of 100 nm to 200 nm.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows.
That is, the above-described problem is (1) “a method for producing an intermediate transfer member to which a toner image obtained by developing a latent image formed on an image carrier with toner is transferred, and at least carbon A step of preparing a dispersion containing black, a resin and a solvent, a step of preparing a coating liquid having an adjusted carbon black content using the dispersion, and applying the coating liquid to an inner surface or an outer surface of a mold. , Forming a film by drying or curing it, and demolding the film, and the dispersion has a volume average particle size Mv1 of carbon black after carbon black dispersion of 150 nm or more and 300 nm or less The volume average particle size Mv2 of the carbon black after being heated in a sealed container at 60 ° C. for 24 hours is 100 nm or more and 200 nm or less, and the Mv2 and the Mv1 The ratio of (Mv2 / Mv1) are provided methods for producing the intermediate transfer member and satisfies the below 1 0.33 or more ",
(2) "The method for producing an intermediate transfer member according to item (1), wherein the resin is either polyimide or polyamide resin",
(3) “The method for producing an intermediate transfer member according to (1) or (2) above, wherein the carbon black solid content in the carbon black dispersion is 5 wt% to 25 wt%” ,
(4) “Adjustment of the carbon black content of the coating liquid is to add a resin solution to the dispersion, and the resin solution contains the same resin as the resin in the carbon black dispersion. The method for producing an intermediate transfer member according to any one of (1) to (3),
(5) The production of the intermediate transfer member according to any one of claims 1 to 4, wherein the resin solid content in the carbon black dispersion is 4 wt% to 40 wt% with respect to the carbon black. Method.
Is achieved.
Further, the above-described problem is (6) “image forming apparatus for performing a primary transfer of a toner image formed on an image bearing member onto an intermediate transfer member, and performing a secondary transfer of the primary transfer image onto a recording medium. An intermediate transfer body used in the above-mentioned intermediate transfer body, which is manufactured by the method of manufacturing an intermediate transfer body according to any one of (1) to (5),
(7) “Intermediate transfer member according to item (6), which is a seamless belt”,
(8) “An image carrier on which a latent image is formed and capable of carrying a toner image, a developing unit for developing the latent image formed on the image carrier with toner, and a toner image developed by the developing unit The image forming apparatus includes an intermediate transfer body on which the toner image is primarily transferred, and a transfer unit that secondary-transfers the toner image carried on the intermediate transfer body to a recording medium. Or an intermediate transfer member according to item (7),
(9) Achieved by “the image forming apparatus according to the item (8), wherein the image forming apparatus is a full-color image forming apparatus, and a plurality of latent image carriers having developing units for respective colors are arranged in series”. Is done.

According to the present invention, it is possible to provide an intermediate transfer member used for an image forming apparatus having the following effects, which has improved the problems of the prior art, and an image forming apparatus using the intermediate transfer member.

According to the invention <1>, an intermediate transfer body having a desired resistance value and high uniformity can be obtained with a stable carbon addition amount regardless of the production process lot or the lot of materials such as carbon black and resin.
According to the invention <2>, an intermediate transfer member excellent in heat resistance, chemical resistance and radiation resistance can be obtained.
According to the invention <3>, the viscosity of the carbon black dispersion liquid can be lowered and can be efficiently dispersed to a target particle size.
According to the invention <4>, shock aggregation of carbon black at the time of preparing an intermediate transfer member coating solution using the dispersion can be suppressed.
According to the invention <5>, the aggregation of carbon black in the carbon black dispersion can be suppressed, and a highly stable carbon black dispersion can be obtained.
According to the invention <6>, a highly durable intermediate transfer member can be obtained.
According to the invention <7>, an image can be efficiently transferred to paper.
According to the invention <8>, it is possible to perform high-quality image formation that does not cause abnormal images over a long period of time.
According to the invention <9>, it is possible to provide an image forming apparatus suitable for full color image formation adapted to higher speed while maintaining quality.

FIG. 2 is a schematic view of a main part for explaining a seamless belt used for a belt member of an image forming apparatus according to the present invention and an image forming apparatus using the same. FIG. 2 is a schematic diagram of a main part illustrating a configuration example of an image forming apparatus in which a plurality of photosensitive drums are arranged in parallel along one intermediate transfer belt provided as a belt member of the image forming apparatus according to the present invention. 1 is a schematic view of a pass-type dispersion apparatus for producing a carbon black dispersion. FIG. The schematic diagram of the dispersion apparatus of the circulation system which manufactures the dispersion liquid of carbon black is shown.

In an electrophotographic apparatus, a seamless belt is used for several members, and an intermediate transfer belt is one of important members that require electrical characteristics. The intermediate transfer belt of the present invention will be described below.

The intermediate transfer belt of the present invention comprises a resin containing a filler for adjusting electric resistance. As the resin, those generally used and available on the market can be used, and from the viewpoint of flame retardancy, fluorine-based resins such as PVDF and ETFE, polyimide or polyamideimide are preferable, but in terms of mechanical strength, From the viewpoint of dispersibility of the resistance control filler, a polyimide resin or a polyamideimide resin is preferable.

On the other hand, as the filler for adjusting electric resistance, organic or inorganic conductive fine particles such as metals, metal oxides, and carbon black, ionic conductive agents, and conductive polymers are used, but they are inexpensive and excellent in productivity. Carbon black is preferably used.
Examples of carbon black include ketjen black, furnace black, acetylene black, thermal black, and gas black. Among these, a solvent or resin having a good compatibility is selected and used. Also, those obtained by appropriately surface-treating these carbon blacks can be used.
Carbon black is used as the resistance adjusting agent, but other resistance adjusting agents described above may be used in combination.

When used as an intermediate transfer belt, the resistance value is preferably 1 × 10 ^ 8 to 1 × 10 ^ 13Ω / □ in surface resistance and 1 × 10 ^ 6 to 1 × 10 ^ 12Ω · cm in volume resistance. From the standpoint of mechanical strength, a carbon black that can be achieved with such an added amount that the film is brittle and does not easily break is selected.

The carbon black content of the intermediate transfer member in the present invention is preferably 15 to 20 wt%. If it is less than this, it becomes difficult to obtain the uniformity of the resistance value, and the fluctuation of the resistance value with respect to an arbitrary potential becomes large, which is not preferable. On the other hand, if it is 25 wt% or more, the mechanical strength of the belt is lowered and the durability is inferior.

Next, the polyimide resin will be described.
<Polyimide>
The polyimide used in the present invention is obtained via a polyamic acid (polyimide precursor) by a reaction between a generally known aromatic polycarboxylic acid anhydride or derivative thereof and an aromatic diamine. That is, polyimide is insoluble in solvents due to its rigid main chain structure, and has infusible properties, so it is first soluble in organic solvents from aromatic polycarboxylic anhydrides and aromatic diamines. New polyimide precursor (polyamic acid or polyamic acid) is synthesized, and at this stage, molding is performed by various methods, and then polyamic acid is heated or chemically dehydrated to cyclize (imidize) And polyimide. The outline of the reaction is shown in the following formula (1).

（式中、Ａｒ１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、Ａｒ２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, Ar1 represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and Ar2 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. In order to effectively express the physical properties of the present invention, it is particularly preferable to use 4,4'-diaminodiphenyl ether as at least one of the components.

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; alcohol solvents such as methanol, ethanol and butanol; cellosolve such as butyl cellosolv or hexamethyl Suhoruamido, .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 more kinds of diamines are dissolved in the above organic solvent or dispersed 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. In this case, the reaction temperature is usually 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, an aromatic polyvalent carboxylic acid anhydride or derivative thereof and an aromatic diamine component are polymerized in about an equimolar amount in an organic polar solvent, so that the polyamic acid is uniformly dispersed in the organic polar solvent. A polyimide precursor solution is obtained in a 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.
Examples of this include Trenys (manufactured by Toray Industries, Inc.), U-Varnish (manufactured by Ube Industries, Ltd.), Rika Coat (manufactured by Nippon Nippon Chemical Co., Ltd.), Optmer (manufactured by JSR), SE812 (manufactured by Nissan Chemical Industries), CRC8000 ( Sumitomo Bakelite Co., Ltd.) is a typical example.

A coating solution is prepared by mixing and dispersing a filler in the synthesized or obtained polyamic acid solution as necessary. 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.

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, for example, 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.
In order to exhibit the intrinsic performance of polyimide, it is preferable to complete imidization by heating to a temperature above the glass transition temperature of the corresponding polyimide.

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 a method for NMR (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 are used. Outer spectroscopy (FT-IR method) is the most common method.

In the Fourier transform infrared spectroscopy (FT-IR method), the imidization rate is defined as, for example, the following formula (a).
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 (a)

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 vibration 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 ring (2) Characteristics of imide Absorbance ratio between 1,380 cm −1 (inflection band of imide ring C—N group) which is one of absorption and 1,500 cm −1 characteristic absorption of benzene ring (3) One of characteristic absorption of imide Absorbance ratio between 1,720 cm −1 (an oscillating band of imide ring C═O group) and 1,500 cm −1 characteristic absorption of benzene ring (4) 1, which is one of characteristic absorption of imide Absorbance ratio between 720 cm −1 and amide group characteristic absorption 1,670 cm −1 (interaction between amide group N—H bending vibration and CN stretching vibration) and amide group over 3000 to 3300 cm −1 If we confirm that the multiple absorption band of origin has disappeared Further, the reliability of completion of imidization is enhanced.

Next, polyamideimide will be described.
<Polyamideimide>
Polyamideimide is a resin having a rigid imide group and an amide group imparting flexibility in the molecular skeleton, and the polyamideimide used in the present invention may have a generally known structure. it can.
Generally, as a method for synthesizing a polyamideimide resin, an acid chloride method (a): a derivative halide of a trivalent carboxylic acid having an acid anhydride group, most typically a chloride compound of the derivative and a diamine are used as solvents. There is known a known method for producing it by reacting in the method (for example, see Japanese Examined Patent Publication No. 42-15637). Alternatively, as another method, an isocyanate method (b): a known method for producing a trivalent derivative containing an acid anhydride group and a carboxylic acid and an aromatic isocyanate in a solvent (for example, Japanese Patent Publication No. 44-19274). No.) are known, and any of them can be used. Each manufacturing method will be described below.

(A) Acid chloride method As a derivative halide compound of a trivalent carboxylic acid having an acid anhydride group, for example, compounds represented by the following formulas (2) and (3) can be used.

（式中、Ｘはハロゲン元素を示す。）

(In the formula, X represents a halogen element.)

式中、Ｘはハロゲン元素を示し、Ｙは−ＣＨ_２−、−ＣＯ−、−ＳＯ_２−または−Ｏ−を示す）

In the formula, X represents a halogen element, and Y represents —CH ₂ —, —CO—, —SO ₂ — or —O—).

In each of the above formulas, the halogen element is preferably chloride, and specific examples of derivatives include terephthalic acid, isophthalic acid, 4, 4 ′ biphenyl dicarboxylic acid, 4, 4 ′ biphenyl ether dicarboxylic acid, 4, 4 ′ biphenyl sulfone dicarboxylic acid. Acid, 4, 4 'benzophenone dicarboxylic acid, pyromellitic acid, trimellitic acid, 3, 3', 4, 4 'benzophenone tetracarboxylic acid, 3, 3,' 4, 4 'biphenylsulfone tetracarboxylic acid, 3, Polyvalent carboxylic acids such as 3 ′, 4 and 4 ′ biphenyltetracarboxylic acid, adipic acid, sebacic acid, maleic acid, fumaric acid, dimer acid, stilbene dicarboxylic acid, 1,4 cyclohexanedicarboxylic acid, and 1,2 cyclohexanedicarboxylic acid Of acid chloride.

On the other hand, the diamine is not particularly limited, and any of aromatic diamine, aliphatic diamine, and alicyclic diamine can be used, and aromatic diamine is preferably used.
Aromatic diamines include m-phenylenediamine, p-phenylenediamine, oxydianiline, methylenediamine, hexafluoroisopropylidenediamine, diamino-m-xylylene, diamino-p-xylylene, 1,4-naphthalenediamine, 1, 5-naphthalenediamine, 2,6-naphthalenediamine, 2,7-naphthalenediamine, 2,2′-bis- (4-aminophenyl) propane, 2,2′-bis- (4-aminophenyl) hexafluoro Propane, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl ether, 3,4-diaminobiphenyl, 4,4'-diaminobenzophenone 3,4-diaminodiphenyl ether, iso Propylidenedianiline, 3,3′-diaminobenzophenone, o-tolidine, 2,4-tolylenediamine, 1,3-bis- (3-aminophenoxy) benzene, 1,4-bis- (4-aminophenoxy) ) Benzene, 1,3-bis- (4-aminophenoxy) benzene, 2,2-bis- [4- (4-aminophenoxy) phenyl] propane, bis- [4- (4-aminophenoxy) phenyl] sulfone Bis- [4- (3-aminophenoxy) phenyl] sulfone, 4,4′-bis- (4-aminophenoxy) biphenyl, 2,2′-bis- [4- (4-aminophenoxy) phenyl] Examples include xafluoropropane, 4,4′-diaminodiphenyl sulfide, and 3,3′-diaminodiphenyl sulfide.

Also, siloxane compounds having amino groups at both ends as diamines, such as 1,3-bis (3-aminopropyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (3-amino Propyl) polydimethylsiloxane, 1,3-bis (3-aminophenoxymethyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (3-aminophenoxymethyl) polydimethylsiloxane, 1, 3, -bis (2- (3-aminophenoxy) ethyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (2- (3-aminophenoxy) ethyl) polydimethylsiloxane, , 3-bis (3- (3-aminophenoxy) propyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (3- (3-aminophenoxy) propi E) If polydimethylsiloxane or the like is used, a silicone-modified polyamideimide can be obtained.

In order to obtain the polyamideimide (polyamideimide resin) in the present invention by the acid chloride method, the above-described trivalent carboxylic acid derivative halide and diamine having an acid anhydride group are used in the same manner as in the production of the polyimide resin. After dissolving in an organic polar solvent, it is reacted at a low temperature (0 to 30 ° C.) to obtain a polyamideimide precursor (polyamide-amic acid).

The organic polar solvent that can be used is the same as that of the polyimide, and a formamide solvent (for example, a sulfoxide solvent such as dimethyl sulfoxide and diethyl sulfoxide, N, N-dimethylformamide, N, N-diethylformamide, etc.), Acetamide solvents (eg, N, N-dimethylacetamide, N, N-diethylacetamide, etc.), pyrrolidone solvents (eg, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, etc.), phenol solvents ( For example, phenol, o-, m-, or p-cresol, xylenol, halogenated phenol, catechol, etc.), ether solvent (eg, tetrahydrofuran, dioxane, dioxolane, etc.), alcohol solvent (eg, methanol, ethanol, butanol) etc , Cellosolve type solvents (e.g., butyl cellosolve, etc.), or hexamethylphosphoramide, γ- butyrolactone. These are preferably used alone or as a mixed solvent, and are not particularly limited as long as they dissolve polyamic acid. Particularly preferably used solvents are N, N-dimethylacetamide and N-methyl-2-pyrrolidone.

After the polyamide / polyamic acid solution obtained as described above is applied to a support (molding mold), conversion (imidation) from polyamic acid to polyimide is performed by treatment such as heating.
Examples of the imidization method include a method of dehydrating and ring-closing by heat treatment, and a method of chemically ring-closing using a dehydrating and ring-closing catalyst. When dehydrating and ring-closing by heat treatment, for example, the reaction temperature is 150 to 400 ° C., preferably 180 to 350 ° C., and the heat treatment time is 30 seconds to 10 hours, preferably 5 minutes to 5 hours. When a dehydration ring closure catalyst is used, the reaction temperature is 0 to 180 ° C., preferably 10 to 80 ° C., and the reaction time is several tens of minutes to several days, preferably 2 to 12 hours. Examples of the dehydration ring closure catalyst include acid anhydrides such as acetic acid, propionic acid, butyric acid, and benzoic acid.

(B) Isocyanate method As the derivative of the trivalent carboxylic acid having an acid anhydride group used in the case of the isocyanate method, for example, a compound represented by the formula (4) or the formula (5) can be used.

（式中、Ｒは水素、炭素数１〜１０のアルキル基またはフェニル基を示す。）

(In the formula, R represents hydrogen, an alkyl group having 1 to 10 carbon atoms, or a phenyl group.)

式中、Ｒは水素、炭素数１〜１０のアルキル基またはフェニル基を示し、Ｙは−ＣＨ_２−、−ＣＯ−、−ＳＯ_２−または−Ｏ−を示す。）

In the formula, R represents hydrogen, an alkyl group having 1 to 10 carbon atoms, or a phenyl group, and Y represents —CH ₂ —, —CO—, —SO ₂ —, or —O—. )

Any of the derivatives represented by the above general formula can be used, but the most typical example is trimellitic anhydride. These trivalent carboxylic acid derivatives having an acid anhydride group can be used alone or in combination depending on the purpose.

Next, as one aromatic polyisocyanate used for the synthesis of the polyamideimide of the present invention, for example, 4,4′-diphenylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, 4,4′-diphenyl ether diisocyanate, 4, 4 '-[2,2-bis (4-phenoxyphenyl) propane] diisocyanate, biphenyl-4,4'-diisocyanate, biphenyl-3,3'-diisocyanate, biphenyl-3,4'-diisocyanate, 3,3'-Dimethylbiphenyl-4,4'-diisocyanate,2,2'-dimethylbiphenyl-4,4'-diisocyanate,3,3'-diethylbiphenyl-4,4'-diisocyanate,2,2'-diethylbiphenyl-4 , 4'-Diisocyanate 3,3'-dimethoxybiphenyl-4,4'-diisocyanate, 2,2'-dimethoxybiphenyl-4,4'-diisocyanate, naphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate and the like. .
These aromatic polyisocyanates can be used alone or in combination. Hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, transcyclohexane-1,4-diisocyanate, hydrogenated m-xylylene diene as necessary. Aliphatic such as isocyanate and lysine diisocyanate, alicyclic isocyanate and trifunctional or higher polyisocyanate can also be used.

After applying a solution containing a polyamidoimide precursor obtained by adjusting the above-described trivalent carboxylic acid derivative having an acid anhydride group and an aromatic polyisocyanate in an organic polar solvent, heat treatment is performed. By doing so, the conversion from the polyamideimide precursor to the polyamideimide is performed. Upon conversion to polyamideimide by this method, polyamideimide is generated without generating a carbonic acid (generally generating carbon dioxide). The following formula (6) shows an example of polyamide imidization when trimellitic anhydride and aromatic isocyanate are used.

(式中、Ａｒは芳香族基を示す。)

(In the formula, Ar represents an aromatic group.)

The polyimide and polyamideimide shown above are usually used alone, but those selected in consideration of compatibility can also be used in combination.
Moreover, the copolymer which has a polyimide repeating unit and a polyamideimide repeating unit may be sufficient.

Next, as a method of manufacturing a seamless belt using the coating liquid containing the polyimide precursor or the polyamideimide precursor, a method of forming a film by applying to the inner surface of a mold on a cylinder, There is a method of forming a film by applying to the outer surface.
In the present invention, both methods can be used. Hereinafter, centrifugal molding, which is one of methods for forming a film on the inner surface, will be described.

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 (coating film coating) is performed so that the coating liquid is uniform over the entire inner surface of the cylinder. Form. 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 (firing furnace) capable of high-temperature treatment, heated in steps, and finally heated at about 250 ° C. to 450 ° C. ( Calcination) and sufficiently imidization or polyamide-imidization of the polyimide precursor or polyamide-imide precursor. 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 previously form a mold release agent or a mold release layer on the mold so that the mold can be easily peeled off.

Next, a method for preparing the coating solution used above will be described.

The coating solution in the present invention is prepared by at least a step of preparing a dispersion containing carbon black, a resin and a solvent, and a step of adjusting the content of carbon black to a predetermined amount by mixing the dispersion with the resin solution. The

First, in the step of preparing a dispersion, a solution in which at least a polyimide or polyamideimide precursor solution and carbon black are mixed in a solvent is added to a carbon black using a disperser such as a bead mill, a ball mill, a nanomizer, a paint shaker, or a jet mill. To prepare a dispersion.
At this time, you may contain additives, such as various dispersing agents, as needed. Further, carbon black that has been previously subjected to some treatment may be used.

Hereinafter, dispersion by a bead mill will be described as an example.
FIG. 3 shows a bead mill dispersing apparatus using a pass method.
The dispersion tank A (301) is charged with the liquid to be dispersed, and the liquid is sent to the disperser (302) by a liquid feed pump. The disperser is filled with beads of a certain size, and this has a mechanism that rotates at high speed inside, and carbon black is atomized by the rubbing force by the beads by this rotation. The atomized liquid is collected in the dispersion liquid discharge tank B (304), and one pass is completed.
The dispersion force at this time is determined by the rotational speed in the disperser, the type of beads, the diameter, and the flow rate of the liquid feeding, and these are set to appropriate conditions.
When the dispersion state of the liquid collected in the dispersion liquid discharge tank B is insufficient, the dispersion tank A is charged again and dispersion is performed again. In the pass method, this is repeated until a sufficiently dispersed liquid is obtained.

FIG. 4 shows a bead mill apparatus using a circulation system.
Unlike FIG. 3, the liquid dispersed by the disperser (402) returns to the dispersion tank A (401). Dispersion proceeds while the liquid before dispersion and the liquid after dispersion are sufficiently stirred.
In this method, the dispersion state of the liquid returning from the disperser is evaluated. In general, management is performed in the time required for dispersion.

The content of carbon black in the dispersion is preferably 5 to 25 wt%, more preferably 10 to 15 wt%. The smaller the carbon black content, the easier it is to disperse. However, considering production, it is wasteful and expensive, so the content is 5% or more. On the other hand, if it is 25% or more, the viscosity is significantly increased, and the dispersion efficiency is lowered.

The precursor solid content of polyimide or polyamideimide in the dispersion is preferably 4 to 40 wt%, more preferably 10 to 30 wt%, based on 100 parts of carbon black.
Carbon black can be dispersed even if it does not contain a polyimide or polyamide imide precursor. However, when it is produced without containing it, in the next step of adjusting the carbon black content, this dispersion and polyimide or When mixing the polyamideimide precursor solution, carbon black is not preferable because it causes shock aggregation.
Therefore, it is preferable to contain 4 wt% or more of the precursor solid content of polyimide or polyamideimide with respect to the carbon black. On the other hand, if it is 40 wt% or more, the viscosity of the solution becomes too high and the dispersion efficiency is lowered, which is not preferable.

You may use suitably additives, such as various dispersing agents, to a dispersion liquid as needed. Moreover, in dispersion | distribution, processes, such as a pre-mixing process and multistage dispersion | distribution by a different disperser, can also be taken.

In the present invention, the dispersion state of carbon in this dispersion is important.
As an index representing the dispersion state of carbon black, there is generally a particle size.
As a method for measuring the particle size, measurement is performed with a measuring instrument such as a centrifugal separation method, a laser diffraction method, or a dynamic light scattering method. For example, the particle size measured with a dynamic light scattering method measuring instrument is preferably dispersed in a volume average particle size of 150 to 300 nm.
However, even if the particle size is dispersed to this extent, it is often impossible to obtain a product of good quality. In particular, depending on the production lot of carbon black, quality often varies and becomes defective.

In the present invention, the carbon black dispersion is put in a sealed container and heated in an atmosphere of 60 ° C. for 24 hours, and the volume average particle diameter (Mv1) before the heating and the volume average particle diameter (Mv2) after the heating are set. The fluctuation (Mv2 / Mv1) is evaluated and measured. Even if the particle size at the time of dispersion is small, the carbon black dispersion having poor quality is likely to cause aggregation of carbon black by heating, so the value of Mv2 becomes larger than Mv1, and the value of Mv2 / Mv1 becomes 1 or more. End up.
The volume average particle size (Mv2) after heating is preferably from 100 nm to 300 nm, and more preferably from 100 nm to 200 nm.
On the other hand, if the value of Mv2 / Mv1 is less than 0.33, the resistance uniformity of the intermediate transfer member molded using the Mv2 / Mv1 and the resistance variation with respect to each bias are both small and good quality, but necessary. Since a large amount of carbon black in the belt is required to control the resistance value, the intermediate transfer member becomes brittle and the durability in the electrophotographic apparatus is inferior.
If Mv2 is not within the above range even if Mv1 is dispersed below 300 nm, additional dispersion is performed, and the dispersion time is adjusted so that Mv2 / Mv1 is 0.33 or more and less than 1. .
Thus, by adjusting the dispersion time, it is possible to determine the occurrence of defective products without forming a film, and it is possible to efficiently produce an intermediate transfer member having a desired resistance value and high uniformity.

The temperature at which the carbon black dispersion is heated is 40 ° C to 80 ° C, preferably 50 ° C to 70 ° C, more preferably 60 ° C. A temperature lower than that is not preferable because a long time is required until a difference between a poorly dispersed carbon black dispersion and a good carbon black dispersion is observed. Conversely, when the temperature is 80 ° C. or higher, the reaction of the resin precursor starts, which is not preferable.
The heating time of the carbon black dispersion is 12 to 72 hours, preferably 18 to 30 hours, more preferably 24 hours. Below that time, due to insufficient heating, there is no difference between the poorly dispersed carbon black dispersion and the well dispersed carbon black dispersion. On the contrary, when the time is longer than that, the carbon black tends to aggregate. Therefore, it is not preferable because the particle diameter increases uniformly regardless of the dispersion state of carbon black.

The particle size of the carbon black dispersion can be measured by diluting the dispersion with a dispersion solvent using, for example, MicrotracUPA-150EX manufactured by Nikkiso Co., Ltd.

Next, the dispersion liquid prepared above is adjusted to have a predetermined resistance value by mixing and diluting a polyimide or polyamideimide precursor solution.
The method of mixing the polyimide or polyamideimide precursor solution into the dispersion is performed by stirring and mixing by using a general stirring device. Since the precursor solution of polyimide or polyamideimide has high viscosity, a machine that can cope with this is selected.
Moreover, since many bubbles are generated in the liquid after stirring, it is preferable to sufficiently remove the bubbles by a method such as vacuum defoaming.
Moreover, in this process, you may contain additives, such as a solvent and a leveling agent, as needed.

<Image forming device>
Next, a seamless belt used in a belt constituting unit provided in the image forming apparatus according to the present invention will be described in detail below with reference to a schematic diagram of a main part. 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 a main part of an image forming apparatus equipped with a belt member 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, the 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 C image forming process after the Bk image forming process, and reading of the C image data by the color scanner starts at a predetermined timing. A C 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 C electrostatic latent image arrives, the revolver developing unit (230) is rotated, and the C developing machine ( 231C) is set at the development position, and the C electrostatic latent image is developed with C toner. Thereafter, the development of the C electrostatic latent image area is continued. When the rear end portion of the C 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 M developing machine (231M) is moved to the developing position. This is also completed before the leading edge of the next Y electrostatic latent image reaches the developing position. Note that the M and Y image forming steps are the same as the Bk and C steps described above because the operations of reading color image data, forming an electrostatic latent image, and developing are the same as those described above.

The Bk, C, M, and Y 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 the registration between 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).

On the upstream side of the belt cleaning blade (504) in the moving direction of the intermediate transfer belt (501), a toner seal member (502) contacting and separating from the belt outer peripheral surface of the intermediate transfer belt (501) is provided. Yes. The toner seal member (502) receives the falling toner that has dropped from the belt cleaning blade (504) during cleaning of the residual toner, and prevents the falling toner from scattering on the transfer path of the transfer paper (P). It is preventing. The toner seal member (502) 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 copying, 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 (Y) image forming process. 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 the 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-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. 2 are arranged in parallel along one intermediate transfer belt. The present invention can also be applied to the image forming apparatus.
FIG. 2 shows four drums including four photosensitive drums (21BK), (21Y), (21M), and (21C) for forming toner images of four different colors (black, yellow, magenta, and cyan). 1 shows an example of the configuration of a type digital color printer.

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 forming a color image 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, and corresponds to each color signal described above. 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) having four writing optical paths. .

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) is removed from the printer main body. 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 member (25). A lubricant application device (27) is disposed downstream of the belt cleaning member (25). The lubricant application device (27) 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.

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples. However, the present invention is not limited by these examples, and these examples are appropriately modified without departing from the gist of the present invention. Is also within the scope of the present invention.

(Production of carbon black dispersion)
・ Carbon black (Specialblack4; Evonik Degussa) 12wt%
Polyimide varnish (U-varnish A (solid content 18%); Ube Industries) 13.3 wt%
・ Solvent (N-methyl-2-pyrrolidone; Mitsubishi Chemical Corporation) 74.7 wt%
The solution in which the above mixture was well mixed was dispersed by a pass method using a bead mill (Apex Mill; manufactured by Kotobuki Kogyo Co., Ltd.). The beads were dispersed for 5 hours using zirconia beads having a diameter of 0.5 mm to prepare a carbon black dispersion A. A portion of the obtained carbon black dispersion was collected in a glass bottle, capped, and then heated for 24 hours in a drier at 60 ° C. to obtain a carbon black dispersion A ′ for evaluation.

(Measurement of volume average particle diameter)
The carbon black volume average particle diameters Mv1 and Mv2 of dispersion A and A ′ were prepared by diluting 200-fold with N-methyl-2-pyrrolidone, and using Microtrac UPA-150EX (manufactured by Nikkiso Co., Ltd.) Measurements were made to determine Mv2 / Mv1 values.

(Preparation of belt coating solution A)
Next, using the dispersion A, the following coating solution was prepared.
・ The above dispersion AX wt%
・ Polyimide solution (U-varnish A (solid content 18%); Ube Industries) Y wt%
・ Leveling agent (FZ2105; Toray Dow Corning) 0.02wt%
The ratio of the carbon dispersion and the polyimide solution (X and Y) in the above blending was adjusted so that the surface resistance value obtained when each dispersion was used was approximately 1 × 10 11Ω / □.

(Preparation of seamless belt A)
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 A is allowed to flow uniformly over the inner surface of the cylinder while rotating the cylinder at 50 rpm (times / min). It was applied by flowing to spread. When the predetermined amount was completely poured and the coating film was evenly spread, the number of revolutions was increased to 100 rpm, the hot air circulating dryer was introduced, and the temperature was gradually raised to 110 ° C. and heated for 60 minutes. The temperature is further raised and heated at 200 ° C. for 20 minutes, and the rotation is stopped, gradually cooled, taken out, put into a heating furnace (baking furnace) capable of high-temperature treatment, and gradually heated to 320 ° C. for 60 minutes. Heat treatment (firing) was performed.
After stopping the heat treatment, the mold was taken out after being slowly cooled to room temperature, and the formed coating film was peeled off from the inner surface of the cylinder to obtain a seamless belt A having a film thickness of 80 μm.

Carbon black dispersion liquid B, belt coating liquid B, and seamless belt B were prepared in the same manner as in Example 1 except that the carbon black of the production lot different from the carbon black of the dispersion liquid prepared in Example 1 was changed. And evaluated.

<Comparative Example 1>
A seamless belt C was prepared and evaluated in the same manner as in Example 1 except that the carbon black of the production lot different from the carbon black of the dispersion prepared in Example 1 and Example 2 was used.

<Comparative Example 2>
A seamless belt D was prepared and evaluated in the same manner as in Example 1, except that the carbon black of the production lot different from the carbon black of the dispersion prepared in Example 1, Example 2, and Comparative Example 1 was changed. Went.

A seamless belt E was produced and evaluated in the same manner as in Example 1 except that the carbon black concentration of the dispersion liquid of Example 1 was 20 wt% and the polyimide varnish concentration was 22.2 wt%.

<Comparative Example 3>
A seamless belt F was produced and evaluated in the same manner as in Example 1 except that the carbon black concentration in the carbon black dispersion was 35 wt% and the polyimide varnish concentration was 38.8 wt%.

<Comparative example 4>
In Example 1, a seamless belt G was prepared and evaluated in the same manner as in Example 1 except that 0.67 wt% of polyimide varnish was added to the carbon black dispersion.

<Comparative Example 5>
In Example 1, a seamless belt H was produced and evaluated in the same manner as in Example 1 except that the polyimide varnish concentration in the carbon black dispersion was changed to 33.4 wt%.

<Comparative Example 6>
A seamless belt I was produced and evaluated in the same manner as in Example 1 except that the dispersion time of carbon black was 11 hours in Example 1.

(Production of carbon black dispersion liquid J and belt coating liquid J)
・ Carbon black (MA100; Mitsubishi Chemical) 12wt%
・ Polyamideimide varnish (Viromax HR16NN (solid content 15%); Toyobo Co., Ltd.) 16wt%
・ Solvent (N-methyl-2-pyrrolidone; Mitsubishi Chemical Corporation) 72 wt%
The solution in which the above mixture was well mixed was dispersed by a pass method using a bead mill (Apex Mill; manufactured by Kotobuki Kogyo Co., Ltd.). The beads were dispersed for 3 hours using φ 1 mm zirconia beads to prepare a carbon black dispersion J. Thereafter, in the same manner as in Example 1, the value of Mv2 / Mv1 was calculated.
The coating solution was also applied in the same manner as in Example 1 to obtain a belt coating solution J.

(Preparation of seamless belt J)
Next, in the same manner as in Example 1, a metal cylinder having an inner diameter of 100 mm and a length of 300 mm having a mirror-finished inner surface was used as a mold, and the cylinder was rotated at 50 rpm (times / minute) while the seamless belt coating was performed. The working fluid J was applied by flowing so as to be uniformly cast on the inner surface of the cylinder.
When the predetermined amount was completely poured and the coating film spread evenly, the number of revolutions was increased to 100 rpm, the hot air circulating dryer was introduced, the temperature was gradually raised to 120 ° C. and heated for 30 minutes.
Thereafter, the rotation is stopped, the cylinder on which the coating film has been formed by slow cooling is taken out, put into a heating furnace (baking furnace) capable of high temperature treatment, heated to 250 ° C., and heated for 60 minutes (baking). did.
Next, after stopping the heating, after slowly cooling to room temperature, the cylinder on which the coating film was formed was taken out, and the formed coating film was peeled off from the inner surface of the cylinder to produce a seamless belt J having a thickness of 80 μm.

The surface resistance values at a total of 12 points of 3 points in the axial direction and 4 points in the circumferential direction of the obtained various belts were measured, and the average value and standard deviation of the common logarithmic values were obtained.
The standard deviation value is preferably 0.20 or less. Above this, the resistance variation is large, which is not preferable for practical use.
Each belt was mounted on an Image MPC4500 (Ricoh), which is an electrophotographic apparatus of the type shown in FIG. 2, and 10,000 test images were output continuously to evaluate the durability of the belt.

<Measurement of surface resistance value>
The surface resistance value 10 seconds after application of 500 V was measured with Hiresta (Dia Instruments) equipped with a URS probe.

Table 1 shows volume average particle diameters and Mv2 / Mv1 values before and after heating of each example and comparative example, carbon black solid content in the belt, average value of logarithm of surface resistivity, standard deviation, and 10,000 sheets. The result of the presence or absence of abnormality of the belt in the output durability evaluation is shown.

From the results shown in Table 1, it can be seen that even in the same production method, the volume average particle size and the amount of carbon in the belt differ depending on the lot of carbon black. Even in the case of a dispersion having the same particle size after dispersion, there is a large difference in the particle size after heating.

From the above results, the volume average particle diameter Mv1 of carbon black in the carbon black dispersion is 150 nm or more and 300 nm or less, and the volume average particle diameter of carbon black after being heated in a sealed container at 60 ° C. for 24 hours. By using a material whose Mv2 is 100 nm or more and 200 nm or less and the ratio of Mv2 and Mv1 (Mv2 / Mv1) is 0.33 or more and less than 1, the material mixing ratio is within the scope of the present invention. Regardless of the production lot and dispersion of the carbon black, it is possible to obtain only a high-quality and highly durable belt with a small variation in resistance value.

(Figure 1)
P Transfer paper L Exposure means 70 Static elimination roller
80 Ground roller 200 Photoconductor drum 201 Photoconductor cleaning device 202 Static elimination lamp 203 Charge charger 204 Potential sensor 205 Toner image density sensor 210 Belt transport device 230 Revolver development unit 231Y Y developer 231K Bk developer 231C C developer 231M M developer 270 Fixing device 271, 272 Fixing roller 500 Intermediate transfer unit 501 Intermediate transfer belt 502 Toner seal member 503 Charging charger
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 600 2 Next 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 roller 20BK, 20M, 20Y, 20C Developing device 21BK, 21M, 21Y, 21C Photoconductor 22 Intermediate transfer belt 23BK, 23M , 23Y, 23C Primary transfer bias roller 25 Belt cleaning member 26 Belt driven roller 27 Lubricant coating device 50 Transfer conveyor belt 60 Secondary transfer bias roller 70 Bias roller (FIG. 3)
301 Distributed input tank A
302 Dispersing machine 303 Liquid feed pump 304 Dispersing liquid discharge tank B

(Fig. 4)
401 Dispersion liquid tank A
402 Disperser 403 Liquid circulation pump 404 Stirrer

JP 2006-348094 A JP 2006-58516 A JP 2007-204531 A JP 2008-152055 A JP-A-6-145378 JP 2008-009248 A

Claims (9)

A method for producing an intermediate transfer member to which a toner image obtained by developing a latent image formed on an image bearing member with toner is transferred, wherein a dispersion containing at least carbon black, a resin and a solvent is produced. A step, a step of preparing a coating liquid in which the carbon black content is adjusted using the dispersion, the coating liquid is applied to the inner surface or the outer surface of a mold, and is formed into a film by drying or curing; The dispersion has a volume average particle size Mv1 of carbon black after carbon black dispersion of 150 nm to 300 nm, and is a sealed container in a 60 ° C. atmosphere. The volume average particle diameter Mv2 of the carbon black after heating for 24 hours is 100 nm or more and 200 nm or less, and the ratio (Mv2 / Mv1) between the Mv2 and the Mv1 is 0.33. Method of manufacturing an intermediate transfer member and satisfies the below upper 1.
The method for producing an intermediate transfer member according to claim 1, wherein the resin is one of polyimide and polyamide resin. The method for producing an intermediate transfer member according to claim 1 or 2, wherein the carbon black solid content in the carbon black dispersion is 5 wt% to 25 wt%. The adjustment of the carbon black content of the coating liquid is to add a resin solution to the dispersion, and the resin solution contains the same resin as the resin in the carbon black dispersion. The method for producing an intermediate transfer member according to any one of 1 to 3. The method for producing an intermediate transfer member according to any one of claims 1 to 4, wherein the resin solid content in the carbon black dispersion is 4 wt% to 40 wt% with respect to the carbon black.   An intermediate transfer member used in an image forming apparatus for performing primary transfer of a toner image formed on an image carrier onto an intermediate transfer member and secondary transfer of the primary transfer image onto a recording medium. The intermediate transfer member manufactured by the method of manufacturing an intermediate transfer member according to any one of claims 1 to 5.   The intermediate transfer member according to claim 6, wherein the intermediate transfer member is a seamless belt.   A latent image is formed and an image carrier capable of carrying a toner image; a developing unit that develops the latent image formed on the image carrier with toner; and a toner image developed by the developing unit is primarily transferred. 8. An image forming apparatus comprising: an intermediate transfer member; and a transfer unit that secondarily transfers a toner image carried on the intermediate transfer member to a recording medium, wherein the intermediate transfer member is defined in claim 6. An image forming apparatus which is an intermediate transfer member. 9. The image forming apparatus according to claim 8, wherein the image forming apparatus is a full-color image forming apparatus, and a plurality of latent image carriers having developing units for respective colors are arranged in series.

Images