JP4902211B2 - Carbon black dispersion liquid, film forming liquid, and image forming apparatus using the same - Google Patents

Description

The present invention, particle size distribution sharp, and the carbon black dispersion the particle size and excellent small dispersibility, relates polyamic acid components membrane solution using the Kerr carbon black dispersion, which on the predetermined surface The present invention relates to a film-formed roller, an endless belt, and an image forming apparatus.

  In an image forming apparatus that is currently widely used, in order to make the constituent rollers and endless belts have uniform and stable electrical characteristics, conventionally, carbon black is dispersed in a dispersion medium to obtain carbon black. A dispersion liquid was prepared, and a resin varnish was further added to obtain a film forming liquid, which was applied and formed on the surface.

In particular, a technique for obtaining an endless belt by centrifugal molding or the like using polyimide as a resin varnish is well known.
One of the important characteristics is electrical characteristics, and it is intended to improve electrical characteristics by controlling the film to be semiconductive. Specifically, specific surface area, amount of oil supply, volatile content, etc. The carbon black has an optimized characteristic (for example, see Patent Document 1 below), and an index that defines an oil absorption amount and a volatile content (for example, see Patent Document 2 below).

However, none of the previously proposed techniques is yet sufficient in terms of dispersibility of the film forming solution, and in order to improve this, the surface of carbon black is surface-treated with a surfactant or resin for dispersion. However, sufficient effects could not be obtained.
Further, although a technique for improving the dispersibility by treating the surface of carbon black with a polymer having a reactive group has been proposed (see, for example, Patent Document 3 below), the dispersibility is improved. Although the effect was obtained, the processing steps were complicated, resulting in high costs.

JP 2001-131410 A JP 2001-152013 A Japanese Patent No. 3435371

  Therefore, in the present invention, a carbon black dispersion liquid having a simple processing process and excellent dispersibility, a polyamide resin film formation liquid using the carbon black dispersion liquid, various members such as a roller and an endless belt coated with the same, and image formation Providing equipment.

Oite this onset Ming reference example, at least, to provide a carbon black dispersion containing carbon black, and a dispersion medium was subjected to a surface treatment with a silicone modified polyimide.

In inventions described above Reference Example, the addition amount of the silicone modified polyimide provides the mosquitoes over carbon black dispersion is 10 parts by weight or less than 0.5 part by weight relative to the 100 parts by weight of carbon black.

In the present invention (the invention of claim 1) is at least, to provide a car carbon black dispersion containing carbon black, and a dispersion medium was subjected to a surface treatment by a silicone modified polyimide and polyimide varnish (a polyamic acid solution) .

Oite this onset Ming reference example has a step of stirring by adding silicone modified polyimide in a dispersion medium in which carbon black is dispersed, mosquitoes over carbon black and that the stirring time is less than 80 hours or more 10 hours A method for producing a dispersion is provided.

In the invention of claim 2, even without least it includes carbon black dispersion according to claim 1, polyimide varnish (a polyamic acid solution) were separately added, polyimide varnish used for the surface treatment (polyamic acid solution) And the polyimide varnish (polyamic acid solution) added separately is the same material.

According to a third aspect of the present invention, there is provided a roller in which a resin layer made of a polyimide resin obtained by applying an imidization treatment after applying the polyimide resin film formation liquid according to the second aspect is formed on at least the surface. provide.

In the invention of claim 4, an endless belt in which a resin layer made of a polyimide resin obtained by applying an imidization treatment after applying the polyimide resin film forming solution according to claim 2 is formed on at least the surface. I will provide a.

In the invention of claim 5, at least a charging device for forming an electrostatic latent image on an image carrier and a developing device for forming a toner image on the image carrier using a developer corresponding to a desired color. An intermediate transfer device that sequentially superimposes and temporarily transfers the toner image on an endless intermediate transfer member, and temporarily transfers the temporary transfer image on the intermediate transfer member onto a transfer material. An image forming apparatus having a fixing device that fixes a toner image on the transfer material by heating or pressurizing a toner image on the transfer material, the charging device, the developing device, the intermediate transfer device, and the fixing At least Table rollers constituting, respectively, at least one endless belt, a resin layer made of polyimide resin obtained by subjecting an imide treatment after coating the polyimide resin film-forming solution according to claim 2 of the device To provide an image forming apparatus are those deposited.

According to the present invention, a carbon black dispersion having a sharp particle size distribution, a small number of coarse particles, a small particle size, and a good dispersibility was obtained (claim 1).
Further, the carbon black dispersion obtained (Claim 2) The polyimide film was used to, by forming a film by this, various members having the uniform and stable electrical properties, for example rollers, endless belt obtained Further, in the image forming apparatus equipped with these, it was possible to reduce density unevenness and to improve the image quality ( claim 3 for the roller, claim 4 for the endless belt, and claim the image forming apparatus). Item 5 ).

Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to the following examples.
The present invention is intended to provide at least a silicone-modified polyimide and polyimide varnish (a polyamic acid solution) of carbon black was subjected to a surface treatment by click, and carbon black dispersion having free dispersion medium, even with this A polyimide film forming liquid is obtained, and a roller, an endless belt, and an image forming apparatus on which a film is formed are provided.
Each constituent material will be described in detail.

(1) Carbon black Carbon black is defined as an aggregate of fine spherical particles obtained by incomplete combustion of various hydrocarbons or carbon-containing compounds. This is because the chemical composition is 98% or more of carbon. It is a substantially pure water carbon material.
The types can be classified according to the production method, and are roughly classified into either pyrolysis of raw material hydrocarbons or incomplete combustion (Table 1 below). Further, it is subdivided according to the type of raw material.
The contact method is a manufacturing method in which a flame is brought into contact with iron or stone, and includes a channel method and a gas black method (roller method) which is an improved method thereof.
Channel black is obtained by a contact method and can be collected by bringing a flame into contact with the bottom surface of the channel steel.
The furnace method is a method for obtaining carbon black by continuously pyrolyzing raw material hydrocarbons by combustion heat of fuel air, and is classified into a gas furnace method and an oil furnace method.
The thermal method is a special production method that uses natural gas as a raw material carbon source and periodically repeats combustion and thermal decomposition, and is characterized in that carbon black having a large particle size can be obtained.
Acetylene black can also be obtained by a kind of thermal method using acetylene as a raw material, but the thermal decomposition of acetylene is an exothermic reaction while other raw materials are endothermic, so it is possible to omit the combustion cycle in the thermal method Thus, there is an advantage that continuous operation is possible.
Acetylene black is characterized by its high crystallinity and high structure compared to ordinary carbon black, so it has excellent conductivity and is applied as a conductivity-imparting agent for dry batteries, various rubbers, and plastics. The

The basic characteristics of carbon black will be described.
Carbon black is blended and dispersed in rubber, resin, paint and ink vehicles, and the important factors for imparting functions such as reinforcement, blackness, and conductivity are the particle size and structure, and the physical chemistry of the particle surface. This is usually called the three major characteristics of carbon black, and various carbon blacks are produced by combining these characteristics.
Three major characteristics of carbon black Particle size: Particle size and surface area Structure: DBP oil supply (ml / 100g) and structure index surface chemical properties: Volatile content (%) and pH

Next, the physical characteristics of carbon black will be described.
(Particle structure)
The minimum unit of carbon black is 30 to 40 carbon six-membered rings bonded together. This network plane is 3 to 5 layers, and is stacked at almost equal intervals (3.5 to 3.9 mm) by Van der Waals force. The crystallites are arranged concentrically and densely in the vicinity of the particle surface, but the arrangement becomes irregular toward the inside.
Such a feature is more conspicuous with fine particles, and thermal black with large particles is in a regular orientation state almost to the center. 1000 to 2000 crystallites are aggregated to form one primary particle, and a combination of these particles chemically and physically is called a structure.
(Particle size and distribution)
Carbon black particles are in the form of dumplings stabbed into a skewer, and each spherical particle only characterizes dumplings and dumpling peaks and valleys. The particle diameter regarded as one particle has a close relationship with performance in various applications, such as reinforcement and blackness.
(Agglomerates and their distribution)
The carbon black particles form dumplings or grape-like aggregates which are stabbed into a skewer, and this is called a structure. Depending on the degree of agglomeration, it is classified into a high (high), normal (medium), and low (low) structure. When blended with rubber, tensile stress and extrusion characteristics, when blended with ink and paint vehicles and resins. It is an important factor that greatly affects dispersibility, blackness, viscosity, conductivity, and the like.
In the structure, the condensed polycyclic aromatic hydrocarbons produced through complex chemical reactions are condensed into fine droplets in a production furnace at 1400 ° C. or higher to form a core precursor, and through mutual collisions. It forms by fusing and solidifying. The structure can be controlled by selecting the shape of the furnace and the dynamic thermodynamic conditions in the furnace. For example, a method of adding a trace amount of an alkali metal salt can be mentioned.
The structure can be measured by the amount of oil supply, compression porosity, bulk density, morphological analysis of the electron microscope image, etc., but the most commonly used oil supply amount is as much as the entanglement of particles, that is, the higher structure carbon black. It applies the phenomenon of absorbing a large amount of oil. For example, it can be measured by a DBP (Dibutyl Phtalate) abstract meter.
(Specific surface area and non-porous specific surface area)
Although the specific surface area of carbon black is almost determined by the size of a single particle, it can be said to be an extremely important characteristic because it has an interaction with other substances on the surface like other solids.
In general, pores are present on the surface of the carbon black, and fine voids are present in the fusion part between the particles. When measuring the specific surface area, it is necessary to clearly distinguish whether or not the obtained value includes the surface area in the pores depending on the measurement principle. Those including the surface area in the pores are referred to as the total specific surface area, and those excluding the surface area in the pores are referred to as the non-porous specific surface area. In general, the specific surface area can be measured by a low-temperature nitrogen adsorption method or iodine adsorption method using the BET equation, and the non-porous specific surface area can be measured by a CTAB adsorption method or a “t” method using an electron microscope.

Next, the chemical characteristics of carbon black will be described.
(Elemental composition and impurities)
Usually, carbon black also contains oxygen, hydrogen, sulfur, ash and the like.
Hydrogen is derived from the dehydrogenation reaction residue in the carbonization process of the raw material hydrocarbon, sulfur from the raw material oil and fuel oil, and ash from the raw material oil and cooling water.
On the other hand, oxygen includes a basic oxide that is bonded by contact with air after the formation of carbon black particles and an acidic oxide that is secondarily generated by reaction with nitrogen dioxide, ozone, nitric acid, etc. It is considered to exist on the particle surface.
Sulfur exists in both chemically bound and free forms, and free sulfur can be extracted by a solvent or an aqueous alkali sulfide solution, but bound sulfur is completely removed even at a high temperature of 1000 ° C. Is difficult to desorb.
The composition of ash is sodium, magnesium chloride and sulfate, calcium carbonate, iron oxide, silica and the like, and the compound tends to be more in furnace black than in channel black.
(Surface functional group)
Most of the chemical reactivity of carbon black is derived from chemical functional groups known as surface oxides and active hydrogen.
The functional group of the acidic oxide is generally said to be a carboxyl group, a hydroxyl group, a quinone group, or a lactone group, and these can be defined by the volatile composition, volatile content, pH, and the like.

  Any of the various carbon blacks described above can be used as the carbon black used in the carbon black dispersion of the present invention.

(2) Silicone-modified polyimide The silicone-modified polyimide for surface treatment of the present invention is represented by the following general formula (1).

However, in general formula (1), X is a tetravalent aromatic ring or aliphatic ring group, R ₁ and R ₆ are divalent organic groups, R _{2 to} R ₅ are alkenyl groups, alkyl groups, phenyl groups, Or a substituted phenyl group is shown, and n shall represent an integer greater than or equal to 5.
This polyimide-modified silicone resin can be produced using a mixture of siloxane diamine, aromatic diamine, and tetracarboxylic dianhydride as a raw material.

The siloxane diamine compound is represented by the following general formula (2).
_{H 2 N-R 1 - (} - SiR 2 R 3 -O-) n-SiR 4 R 5 -R 6 -NH 2 ··· (2)
However, R _1, R ₆ is a divalent organic group, R ₂ to R ₅ represents an alkyl group, a phenyl group, or a substituted phenyl radical, n denote an integer of 5-50.
Specifically, bis (3-aminopropyl) tetramethyldisiloxane, bis (10-aminodecamethylene) tetramethyldisiloxane, dimethylsiloxane tetramer having an aminopropyl end group, octamer, bis (3- Aminophenoxymethyl) tetramethyldisiloxane and the like.

  Examples of aromatic diamines include (1) diphenylalkane diamine compounds such as (1) biphenyl diamine compounds, diphenyl ether diamine compounds, benzophenone diamine compounds, diphenylsulfone diamine compounds, diphenylmethane diamine compounds, and 2,2-bis (phenyl) propane. Compound, 2,2-bis (phenyl) hexafluoropropane diamine compound, diphenylene sulfone diamine compound, (2) di (phenoxy) benzene diamine compound, di (phenyl) benzene diamine compound, (3) di “Aromatic diamine compounds having 2 or more, especially 2 to 5 aromatic rings (benzene rings, etc.) such as (phenoxyphenyl) hexafluoropropane diamine compounds, bis (phenoxyphenyl) propane diamine compounds, etc. Aromatic diamines containing predominantly. These may be used alone or in combination of two or more.

  Examples of the aromatic diamine include diphenyl ether diamine compounds such as 1,4-diaminodiphenyl ether and 1,3-diaminodiphenyl ether, 1,3-di (4-aminophenoxy) benzene, 1,4-bis (4- Di (phenoxy) benzene-based diamine compounds such as aminophenoxy) benzene, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane A bis (phenoxyphenyl) propane-based diamine-based compound such as

  Examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 3,3 ′, 4, 4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3 ′, 3,4′-biphenyltetracarboxylic dianhydride, bis (3 , 4-Dicarboxyphenyl) ether dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylsulfone dianhydride, ethylene glycol bistrimellitate dianhydride, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane dianhydride, etc. 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 3,3 ′, 4, '- biphenyltetracarboxylic acid dianhydride, 2,3', 3,4'-biphenyltetracarboxylic dianhydride, and the like.

The polyimide-modified silicone resin used in the present invention can be produced by a known method using the various compounds mentioned above.
For example, a method in which these are heated in an organic solvent in the presence of a catalyst such as tributylamine, triethylamine, or triphenyl phosphite as necessary to obtain polyimide directly, and tetracarboxylic dianhydride and diamine are added in an organic solvent. After obtaining polyamic acid which is a polyimide precursor by reaction, a dehydration catalyst such as p-toluenesulfonic acid is added if necessary, and imidation is carried out by heating to prepare polyimide, or polyamic acid is mixed with acetic anhydride. A method of chemically ring-closing by adding a dehydrating ring-closing agent such as an acid anhydride such as propionic anhydride or benzoic anhydride, a carbodiimide compound such as dicyclohexylcarbodiimide, and a ring-closing catalyst such as pyridine, isoquinoline, imidazole or triethylamine as necessary. Etc.

(3) Dispersion medium As a dispersion medium used for this invention, a conventionally well-known thing can be applied as a solvent of a polyamic acid.
For example, it is used for amide solvents such as NMP (N-methylpyrrolidone), DMF (N, N-dimethylformamide), DMAc (N, N-dimethylacetamide), polyamic acids such as γ-butyrolactone, and polyimide resins. A dipole solvent, ethyl lactate, methoxymethyl propionate, propylene glycol monomethyl ether acetate, etc. can be used, and the amount used is controlled so as to have a necessary solid content and viscosity. In particular, NMP (N-methyl-2-pyrrolidone) is most preferred.

Next, a surface treatment method for carbon black will be described.
The surface of carbon black particles has a condensed aromatic ring, and various surface treatments shown below are possible.
(A Surface oxidation treatment)
When carbon black is treated with an oxidizing agent, a carboxyl group or a phenolic hydroxyl group is introduced into the condensed aromatic ring (Φ) on the particle surface.
Furthermore, the condensed aromatic ring on the surface of carbon black reacts with the following various reagents, and various functional groups can be introduced onto the particle surface.
Φ-H + HNO ₃ → Φ-COOH and Φ-OH
Φ-H + H ₂ O ₂ → Φ-OH
Φ-H + HNO ₃ / H ₃ SO ₄ → Φ-NO ₂ (reduction) → Φ-NH ₂
Φ-H + CH ₂ O / OH- → Φ-CH ₂ OH
Φ-H + R-Cl / AlCl ₃ → Φ-R
Φ-H + HOOC-RN = N-R-COOH → Φ-R-COOH
Φ-H + X-Φ-COOCOO-Φ-X → Φ-OCO-Φ-X
Φ-H + BuLi / TMEDA → Φ-Li
Φ-H + NaNH ₂ → Φ-Na

(B Dispersion by surfactant)
Carbon black may be surface-treated by dispersing it with a known anionic surfactant, nonionic surfactant, cationic surfactant, amphoteric surfactant or the like.
Suitable surfactants include interfacial polyoxyethylene alkyl ether acetates, dialkyl sulfosuccinates, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene polyoxypropylene block copolymers, acetylene glycols Surfactant is mentioned.

(C Polymer (resin) dispersion)
Carbon black may be dispersed by steric hindrance repulsion of the polymer dispersant and surface treatment may be performed.
Examples of the polymer dispersant include poly (N-vinyl-2-pyrrolidone), poly (N, N′-diethylacrylazide), poly (N-vinylformamide), poly (N-vinylacetamide), poly (N -Vinylphthalamide), poly (N-vinylsuccinamide), poly (N-vinylurea), poly (N-vinylpiperidone), poly (N-vinylcaprolactam), poly (N-vinyloxazoline) and the like.
These may be used alone or in combination of two or more.
In addition to this, within the scope of the object of the present invention, a polymer material, a surfactant, or a dispersion stabilizer for inorganic salt damage may be used.

(D encapsulation process)
Carbon black is surface-treated with resin and dispersed in a solvent in a coated state, or carbon black is impregnated with resin, that is, the surface layer or the inside, or the carbon black exists in the whole. It may be.
By making these states, properties such as dispersion stability, surface wettability, rheological properties, and electrical properties can be improved.
In particular, with regard to dispersion stability, the dispersibility of the graft chain in a good solvent (easily dispersible in a dispersion medium and stability after dispersion) is remarkably improved. Since it is easily and uniformly dispersed in the polymer matrix, there is a feature that a constant resistance value can be obtained over a wide area.

(E grafting treatment)
Carbon black may be subjected to a grafting treatment.
Based on the grafting mechanism, it can be classified as follows.
(A) Graft polymerization on the surface of carbon black A method in which a vinyl monomer is polymerized using a polymerization initiator in the presence of carbon black, and the growing polymer chain generated in the system is captured on the particle surface.
(B) Graft polymerization from carbon black surface A method of growing a graft chain from a polymerization initiating group introduced to the carbon black surface.
(C) Grafting reaction between carbon black surface and polymer A method by a reaction between a functional group on the carbon black surface and a reactive polymer.
Among the above methods, the method (a) can be most easily performed, but since a non-grafted polymer is predominantly produced, a product having a large graft ratio cannot be obtained.
On the other hand, the system (b) is characterized in that a polymer (graft chain) grows outward from the carbon black surface, so that a product having a high graft rate can be obtained.
Furthermore, according to the method (c), there is a great feature that the molecular weight and number of graft chains can be controlled, and a graft having a relatively large graft ratio can be obtained.

(F Gas phase oxidation method)
The surface of carbon black may be oxidized by ozone treatment or plasma treatment.
By irradiating the carbon black with plasma, a hydroxyl group or a carboxyl group can be attached to the surface of the carbon black by the high energy of the plasma.

From the viewpoint that surface treatment can be performed most simply, the method of (C polymer (resin) dispersion) is effective. However, since there has not been a resin dispersant that can obtain an ideal particle size distribution or particle size, improvement of the surface treatment method has been demanded.
From this point of view, in the present invention, a desired particle size distribution and particle size are realized by using carbon black whose surface is treated with silicone-modified polyimide and a dispersion medium.

Next, the dispersion of carbon black and the film forming solution manufacturing process will be described.
Step A: Pigment + vehicle + solvent → premix (1) → main dispersion (kneading dispersion) (2) → carbon black dispersion Step B: carbon black dispersion + dilution adjustment (3) → film formation solution Step A , B to prepare a film forming solution.

The premixing step (1) (premixing) will be described.
This is a step of producing a paste having an optimum mixed composition and optimum flow state to be applied to the main dispersion machine of the main dispersion step which is the next step. The purpose is to allow the vehicle to penetrate the carbon black particle aggregate so that the surface is completely wetted and to crush the coarse particle aggregate.

The main dispersion step (2) (grinding dispersion) will be described.
This is a step of dispersing a particle aggregate wetted with a vehicle to a particle size required for a film-forming solution by impact or shear energy.
The purpose is to disperse the carbon black until it is close to an aggregate (aggregate) to adsorb the resin component in the vehicle on the surface of the carbon black.

The dilution adjustment step (3) (let down) will be described.
This is a step in which a necessary amount of resin, solvent and additives are added to a paste having a high pigment concentration to adjust the dilution until the desired viscosity and composition are obtained.
Since various resin solutions and solvents are added to the paste having a high pigment concentration, the pigment is diluted so as not to cause reaggregation by adjusting the addition speed, order, temperature, stirring conditions, and the like.

Next, the dispersion apparatus will be described.
Various dispersers are used for reasons such as dispersion viscosity, solvent evaporability, production method, or final dispersed particle size.
The main ones are listed below.
(A) Kneading type: kneader, planetary mixer, etc.
The greater the viscosity of the raw material, the greater the shear stress generated, so it is widely used for kneading hard pastes.
(B) Compression shear type: 3-roll mill, 2-roll mill, etc.
It is a disperser that applies a large shear stress while applying pressure to the gap between rollers, and is applied to a high viscosity (possible up to about 1000 Pa · s) and a large adhesive force.
(C) Stir and mix type: colloid mill, Kady Mill, etc.
An impeller rotating at a high peripheral speed (300 to 1200 m / min) gives a high shear rate.
(D) Grinding shear type: bead mill, ball mill, etc.
This is a disperser that disperses by impact and shear stress of a ball or bead, and a shear stress of about 10 ² to 10 ³ Pa is applied by a ball mill and 10 ⁴ to 10 ⁵ Pa is applied by a bead mill.
Both bead mills and ball mills are used to disperse volatile low-viscosity materials (possible up to several Pa · s).
In the present invention, a grinding and shearing type dispersion apparatus is preferably used, and the dispersion time is preferably 10 hours or more and 80 hours or less.
If the dispersion time is less than 10 hours, the coarse particle aggregate remains without being crushed sufficiently, or if it exceeds 80 hours, it will fall into an overdispersed state, and in all cases, the desired particle size distribution and particle size desired by us will be obtained. I can't.

Next, a method for imidizing the polyimide resin film forming solution will be described.
(1) Although it can imidize by the method of heating or (2) chemical method, since the method of (1) is the method of converting to a polyimide by heating at 200-350 degreeC, it is simple. In addition, a polyimide resin can be obtained practically. However, in the method (2), the polyamic acid is treated with a dehydrating cyclization reagent such as a mixture of a carboxylic acid anhydride and a tertiary amine, and then heated to complete imidization. Compared with the method (1), the method is complicated and costly, so the method (1) is frequently used practically.

In order to complete imidization by heating, the intrinsic performance of the polyimide cannot be exhibited unless it is heated above the glass transition temperature of the polyimide used essentially.
In order to evaluate the degree of imidization, the imidation rate is usually measured.
Various methods for measuring the imidization rate have been known in the past, and nuclear magnetic resonance is calculated from the integral ratio of 1H attributed to an amide group near 9 to 11 ppm and 1H attributed to an aromatic ring near 6 to 9 ppm. There are spectroscopic methods (NMR methods), Fourier transform infrared spectroscopic methods (FT-IR method), methods for quantifying moisture accompanying imide ring closure, and carboxylic acid neutralization titration methods, but most commonly, Fourier transform infrared spectroscopy Method (FT-IR method) is used.
In the Fourier transform infrared spectroscopy (FT-IR method), the imidization rate can be defined as follows.

Imidation ratio = (number of moles of imide group in the firing stage) / (number of moles of imide group when theoretically imidized at 100%) × 100
This is determined from the absorbance ratio of the characteristic absorption of the imide group of IR.
Specific examples are given below.
(1) Absorbance ratio between 725 cm ^-1 (immobilization vibration band of imide ring C = O group) which is one of the characteristic absorptions of imide and benzene ring characteristic absorption of 1015 cm ^-1 (2) 1 of characteristic absorption of imide Absorbance ratio between 1380 cm ⁻¹ (inflection vibration band of imide ring C—N group) and characteristic absorption 1500 cm ^{−1 of} benzene ring (3) 1720 cm ⁻¹ (imide ring) which is one of characteristic absorption of imide Absorbance ratio of C = O group bending vibration band) and characteristic absorption 1500 cm ^{-1 of} benzene ring (4) 1720 cm ^-1 which is one of characteristic absorptions of imide and characteristic absorption 1670 cm ^-1 (amide group) Absorbance ratio between N—H bending vibration and C—N stretching vibration) The imidization ratio can be evaluated using these.
Further, if it is confirmed that the amide group-derived multiple absorption band from 3000 to 3300 cm ⁻¹ disappears, the reliability of imidization completion is further increased.

Carbon black dispersion of the present invention, when the surface treatment of carbon black, together with the silicone modified polyimide, added polyimide varnish (the polyamic acid solution) at the same time.
This allows the surface of the carbon black to be treated simultaneously with not only the silicone-modified polyimide but also polyimide, so that when the polyimide is added, the particle size is reduced without causing shock aggregation or the like when adding polyimide. Thus, a polyimide film-forming solution having a small size and few coarse particles can be obtained.

Next, polyimide will be described.
The polyimide is generally obtained by a condensation reaction between an aromatic polyvalent carboxylic acid anhydride or a derivative thereof and an aromatic diamine.
However, due to its rigid main chain structure, it has insoluble and infusible properties, so firstly, a polyamic acid (or polyamic acid to polyimide precursor) soluble in an organic solvent is synthesized from an acid anhydride and an aromatic diamine, At this stage, molding is performed by various methods, and then polyimide is obtained by dehydration cyclization (imidization) by heating or a chemical method.
This is shown in the following equation.

In the above formula, Ar ₁ and Ar ₂ represent a tetravalent aromatic residue containing at least one carbon 6-membered ring.

A specific example is given about the aromatic polyhydric carboxylic acid anhydride which is an example of a raw material.
For example, ethylenetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 2,2 ′, 3 , 3′-benzophenonetetracarboxylic 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, -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 admixture of two or more.

Next, a specific example is given about the aromatic diamine used by mixing.
For example, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 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-aminophenyl) sulfone, bis (4-aminophenyl) sulfone, 3,3′-diaminobenzophenone, 3, 4′-diaminobenzophenone, 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, -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-aminophen Xy) 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'- Bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [4- (4-a No-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone, bis [4- {4- (4-amino Phenoxy) 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 may be used alone or in combination of two or more.

A polyimide precursor (polyamic acid) is obtained by polymerizing the aromatic polyvalent carboxylic acid anhydride component and the diamine component in a substantially equimolar organic polar solvent.
A specific method for producing a polyamic acid will be described.

Examples of the organic polar solvent used for 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, catechol, ether solvents such as tetrahydrofuran, dioxane, dioxolane, alcohol solvents such as methanol, ethanol, butanol, cellosolve such as butyl cellosolv, or hexamethylphosphor Bromide, γ- butyrolactone, and the like. These may be used alone or as a mixed solvent as appropriate.
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.

First, 1 type or multiple types of diamine is melt | dissolved in said organic solvent, or it diffuses in slurry form in inert gas atmosphere, such as argon and nitrogen.
When at least one aromatic polycarboxylic acid anhydride or derivative thereof is added to this solution in a solid state, in an organic solvent solution state or in a slurry state, ring-opening polyaddition reaction is accompanied by heat generation. Occurs, the viscosity of the polymerization solution increases rapidly, and a high molecular weight polyamic acid solution is obtained.
The reaction temperature at this time is −20 ° C. to 100 ° C., desirably 60 ° C. or less. The reaction time is 30 minutes to 12 hours.
In this reaction, contrary to the above addition procedure, first, the aromatic polycarboxylic acid anhydride or derivative thereof is dissolved or diffused in an organic solvent, and the solution of the diamine in a solid or organic solvent or A slurry may be added.
Moreover, you may make it react simultaneously, and the mixing order of an acid dianhydride component and a diamine component is not limited.
The aromatic polycarboxylic acid anhydride or derivative thereof and the aromatic diamine component are weighed approximately equimolarly and dissolved in the organic polar solvent.
In the present invention, the order of adding the aromatic tetracarboxylic dianhydride and the aromatic diamine is not limited. You may add simultaneously. Moreover, you may mix the organic polar solvent which melt | dissolved each.
As described above, the polyamic acid composition according to the present invention is obtained by subjecting an aromatic polycarboxylic acid anhydride or a derivative thereof and an aromatic diamine component to an equimolar amount by a polymerization reaction in an organic polar solvent so that the polyamic acid is organic. A polyamic acid solution that is uniformly dissolved in the polar solvent is obtained.

Although the polyamic acid composition described above can be easily synthesized as described above, a commercially available polyimide varnish in which a polyamic acid is dissolved in an organic solvent can be applied.
For example, Trenys (manufactured by Toray Industries, Inc.), U-Varnish (manufactured by Ube Industries, Ltd.), Rika Coat (manufactured by Shin Nippon Chemical Co., Ltd.), Optmer (manufactured by JSR), SE812 (manufactured by Nissan Chemical Industries), CRC8000 (manufactured by Sumitomo Bakelite) Etc.

  Since the carbon black dispersion liquid and film forming liquid of the present invention are particularly stable in obtaining uniform electric characteristics and excellent in film forming properties, it is possible to obtain a uniform film by forming a coating film on the surface using this. It is possible to produce rollers and endless belts with stable electrical properties. They can be mounted on an electrophotographic copying machine, a laser printer, or the like, and can be mounted on an image forming apparatus that can stably obtain uniform and high-quality images.

Next, the image forming apparatus will be described.
The image forming apparatus of the present invention includes at least a charging device that forms an electrostatic latent image on an image carrier, and a developing device that forms a toner image on the image carrier using a developer corresponding to a desired color. An intermediate transfer device that sequentially superimposes and temporarily transfers the toner image on an endless intermediate transfer member, and temporarily transfers the temporary transfer image on the intermediate transfer member onto a transfer material. It is assumed that the image forming apparatus includes a fixing device that heats or pressurizes a toner image on a transfer material to fix the toner image on the transfer material.
At least one of the roller and the endless belt constituting each of the charging device, the developing device, the intermediate transfer device, and the fixing device has a resin layer made of the polyimide resin of the present invention formed on at least the surface. It is what.
As an image forming apparatus, for example, an electrophotographic apparatus having a color function such as a color copying machine or a color printer is widely used.
A conventionally known color electrophotographic apparatus is provided with a plurality of color developing devices around one photoconductor, and a toner is attached by these developing devices to form a composite toner image on the photoconductor. A so-called one-drum type that records a color image on a sheet, and a plurality of photoconductors provided side by side, each having a developing device, and forming a single color toner image on each photoconductor, There is a so-called tandem type in which monochromatic toner images are sequentially transferred to record a composite color image on a sheet.

Comparing the one-drum type and the tandem type, the former has one photoconductor, so that there is an advantage that the size can be reduced relatively and the cost can be reduced. Since full-color images are formed by repeating image formation four times (usually four times), it is difficult to speed up image formation.
The latter, on the contrary, has the advantage that it is easy to increase the speed of image formation, although it is disadvantageous in that the size is increased and the cost is increased.
Tandem type has been attracting attention because full-color is required to be as fast as monochrome.

A schematic view of an example of a tandem type electrophotographic apparatus is shown in FIGS.
As shown in FIG. 1, a direct transfer system in which an image on each photoconductor 1 is sequentially transferred onto a sheet S conveyed by a sheet conveying belt 3 by a transfer device 2, and as shown in FIG. Indirect transfer system in which images on 1 are sequentially transferred to an intermediate transfer body 4 by a primary transfer device 2 and then images on the intermediate transfer body 4 are collectively transferred to a sheet S by a secondary transfer device 5. is there.
The transfer device 5 is a transfer conveyance belt, but there is also a roller type.

Compare the direct transfer method with the indirect transfer method.
In the direct transfer method, the sheet feeding device 6 must be disposed on the upstream side of the tandem type image forming apparatus T on which the photoreceptors 1 are arranged, and the fixing device 7 must be disposed on the downstream side. There are drawbacks.
In contrast, the indirect transfer method can set the secondary transfer position relatively freely.
The sheet feeding device 6 and the fixing device 7 can be arranged so as to overlap with the tandem image forming apparatus T, and there is an advantage that downsizing is possible.
Further, in the direct transfer method, the fixing device 7 is disposed close to the tandem type image forming apparatus T in order not to increase the size in the sheet conveyance direction. Therefore, the fixing device 7 cannot be disposed with a sufficient margin that the sheet S can bend, and an impact when the leading edge of the sheet S enters the fixing device 7 (particularly with a thick sheet) or the fixing device. Due to the difference in speed between the sheet conveyance speed when passing through the sheet 7 and the sheet conveyance speed by the transfer conveyance belt, there is a drawback that the fixing device 7 tends to affect image formation on the upstream side.
On the other hand, in the indirect transfer method, the fixing device 7 can be arranged with a sufficient margin that the sheet S can be bent, and therefore the fixing device 7 can hardly affect the image formation. Has the advantage.

In view of the foregoing, indirect transfer type tandem type electrophotographic apparatuses are particularly noted to be particularly excellent.
Then, as shown in FIG. 2, the color electrophotographic apparatus removes transfer residual toner remaining on the photosensitive member 1 after the primary transfer by the photosensitive member cleaning device 8 to clean the surface of the photosensitive member 1, and re-images. It is made to prepare for formation.
Further, the transfer residual toner remaining on the intermediate transfer body 4 after the secondary transfer is removed by the intermediate transfer body cleaning device 9 to clean the surface of the intermediate transfer body 4 so as to prepare for the image formation again.

FIG. 3 shows a schematic configuration diagram of an electrophotographic apparatus of a tandem type indirect transfer system as an example of the image forming apparatus of the present invention.
In FIG. 3, 100 is a copying apparatus main body, 200 is a paper feed table, 300 is a scanner mounted on the copying apparatus main body 100, and 400 is an automatic document feeder (ADF) further mounted thereon.
The copying machine main body 100 is provided with an endless belt-like intermediate transfer member 10 at the center, and is capable of rotating and transporting clockwise around the drawing in the three support rollers 14, 15 and 16.
In this example, an intermediate transfer body cleaning device 17 for removing residual toner remaining on the intermediate transfer body 10 after image transfer is provided on the left side of the second support roller 15 among the three support rollers. .
Of the three support rollers, yellow, cyan, magenta, and black are arranged on the intermediate transfer body 10 stretched between the first support roller 14 and the second support roller 15 along the transport direction. The four image forming means 18 are arranged side by side, and the tandem image forming apparatus 20 is configured thereby.

An exposure device 21 is provided on the tandem image forming apparatus 20.
On the other hand, a secondary transfer device 22 is provided on the side opposite to the tandem image forming apparatus 20 with the intermediate transfer body 10 interposed therebetween.
The secondary transfer device 22 has a configuration in which a secondary transfer belt 24, which is an endless belt, is stretched between two rollers 23, and is pressed against the third support roller 16 via the intermediate transfer body 10. The image on the intermediate transfer body 10 is transferred to a sheet.

A fixing device 25 for fixing the transfer image on the sheet is provided beside the secondary transfer device 22.
The fixing device 25 has a configuration in which a pressure roller 27 is pressed against a fixing belt 26 that is an endless belt.
The secondary transfer device 22 described above also has a sheet transport function for transporting the image-transferred sheet to the fixing device 25.
As the secondary transfer device 22, a transfer roller or a non-contact charger may be arranged.
In the example shown in FIG. 3, the sheet reversal is performed under the secondary transfer device 22 and the fixing device 25 to invert the sheet so as to record images on both sides of the sheet in parallel with the tandem image forming apparatus 20 described above. A device 28 is provided.

An operation when forming (copying) an image using the electrophotographic apparatus shown in FIG. 3 will be described.
A document is set on the document table 30 of the automatic document feeder 400. Alternatively, the automatic document feeder 400 is opened, a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed and pressed.
When a start switch (not shown) is pressed, the document is conveyed and moved onto the contact glass 32. On the other hand, when the document is set on the contact glass 32, the scanner 300 is immediately driven, and the first traveling body 33 and the second traveling body 34 are operated.
Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.

When a start switch (not shown) is pressed, one of the support rollers 14, 15 and 16 is driven to rotate by a drive motor (not shown), and the other two support rollers are driven to rotate to perform intermediate transfer. The body 10 is rotated and conveyed.
At the same time, the photoconductors 40 are rotated by the individual image forming units 18 to form black, yellow, magenta, and cyan single color images on the photoconductors 40, respectively. Then, along with the conveyance of the intermediate transfer member 10, the single color images are sequentially transferred to form a composite color image on the intermediate transfer member 10.

On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 44 provided in the paper bank 43 in multiple stages and separated. The paper is separated one by one by the roller 45 and put into the paper feed path 46, conveyed by the transport roller 47, led to the paper feed path 48 in the copying machine main body 100, abutted against the registration roller 49 and stopped.
Alternatively, the sheet feed roller 50 is rotated to feed out the sheets on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped.
Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer member 10, the sheet is fed between the intermediate transfer member 10 and the secondary transfer device 22, and transferred by the secondary transfer device 22. A color image is recorded on the sheet.

The sheet after the image transfer is conveyed by the secondary transfer device 22 and sent to the fixing device 25, and heat and pressure are applied to the fixing device 25 to fix the transferred image. The paper is discharged at 56 and stacked on the paper discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and an image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.
On the other hand, the intermediate transfer body 10 after the image transfer is removed by the intermediate transfer body cleaning device 17 to remove residual toner remaining on the intermediate transfer body 10 after the image transfer, so that the tandem image forming apparatus 20 can prepare for another image formation.
Here, the registration roller 49 is generally used while being grounded, but it is also possible to apply a bias for removing paper dust from the sheet.
In the tandem image forming apparatus 20 described above, the individual image forming means 18 is more specifically, for example, as shown in FIG. 3, around a drum-shaped photoconductor 40, a charging device 60, a developing device 61, and a primary transfer device. 62, a photoconductor cleaning device 63, a charge removal device 64, and the like.

  The polyimide resin film-forming solution of the present invention is applied to a roller and an endless belt that can be mounted on the above-described image forming apparatus and have uniform and stable electrical characteristics.

A method for producing the roller of the present invention will be described.
Film formation can be performed by casting a polyimide resin film-forming solution on a predetermined carrier (support) and then removing the solvent by drying.
Here, the carrier is not particularly limited, and a carrier applicable to a general solution casting method can be used as appropriate. For example, a metal roller such as SUS or Al, a conductive resin roller, or the like. And rubber rollers.
However, when a high boiling point solvent such as N-methyl-2-pyrrolidone or N, N-dimethylacetamide is used as the solvent, it is necessary to select it according to the properties of the film-forming body (carrier).
The method for casting the polyimide resin film-forming solution on a predetermined carrier is not particularly limited. For example, a conventionally known method such as a doctor knife, Meir bar, roll coat or the like can be applied.
The casting of the polyimide resin film-forming solution can be applied using a spray, brush, roll, spin coat, dipping tool or the like. When a desired film thickness cannot be obtained by a single application, it can be applied repeatedly.

A method for producing the endless belt of the present invention will be described.
As a typical method for producing a belt substrate using the polyimide resin film of the present invention, there is a centrifugal molding method. This is because a raw material solution (hereinafter sometimes referred to as coating solution) as a belt material is poured from a spray or nozzle into a cylindrical mold that rotates a resin solution dissolved in a solvent, and this mold is rotated at high speed. However, this is a method for producing an endless belt by a method (so-called centrifugal molding method) for forming an endless shaped body by spreading the coating liquid by the centrifugal force and solidifying the film as a uniform film.
According to this method, since the applied coating solution is spread by centrifugal force, a coating layer having a relatively uniform thickness can be obtained.
In this centrifugal molding method, after a fluid coating solution is applied to the inner surface of a cylindrical mold, it is rotated with a high-speed centrifugal force to overcome the surface energy of the coating solution aggregation in order to make the film thickness uniform. Then, the coating film is spread to make the film uniform.
The coating solution is prepared by diluting the raw material varnish with a solvent to the mold. For this reason, the coating solution is uniformly applied to the inner surface of the mold when rotating at high speed, but gradually accumulates at the bottom of the mold when the rotation is stopped or the rotational speed is reduced. Therefore, according to this centrifugal molding method, the solvent must be removed and solidified while maintaining the state of a uniform solution film.

It was confirmed that the roller and the endless belt produced by the above-described method and coated with the polyimide film-forming liquid of the present invention had uniform and stable electric resistance.
In addition, it is confirmed that by mounting such a roller with improved resistance uniformity and an endless belt, density unevenness is reduced in the image forming apparatus and effective image quality can be improved. It was.

Hereinafter, although the specific Example of this invention is given and demonstrated, this invention is not limited to the example shown below.
[Reference Examples 1 and 2], [Comparative Examples 1 and 2]
(Carbon black dispersion component)
Dispersant 1.5 parts by weight carbon black (Special Black4: Degussa) 10 parts by weight NMP solvent 100 parts by weight

Here, the following were used as a dispersing agent.
Reference Example 1 : Silicone modified polyimide (SMP3001: manufactured by Shin-Etsu Chemical: solid content 40 wt%)
Reference Example 2 : Silicone modified polyimide (SMP3002: manufactured by Shin-Etsu Chemical Co., Ltd .: solid content 40 wt%)
Comparative example 1: Additive-free comparative example 2: Linear alkyl (C ₁₀ -C ₁₄ ) benzenesulfonic acid (soft washing: Japanese fats and oils)

Each carbon black dispersion liquid component was placed in a glass stirring pot together with zirconia balls (1 mmφ) and stirred for 15 hours.
After stirring, the following items were evaluated with a particle size distribution measuring device (Nanotrack, manufactured by Nikkiso Co., Ltd.). The evaluation results are shown in [Table 2] below.

(1) Volume average particle diameter Mv (μm): 0.4 μm or less is preferable, and 0.3 μm or less is most preferable.
(2) Median diameter D50 (μm): 0.35 μm or less is preferable, and 0.3 μm or less is most preferable.
(3) Maximum coarse particle diameter D100 (μm): 1.5 μm or less is preferable, and 1.0 μm or less is most preferable.
(4) Standard deviation sd of particle size distribution width: 0.25 μm or less is preferable, and 0.20 μm or less is most preferable.

[Reference Examples 3 to 7]
(Carbon black dispersion component)
Dispersant X parts carbon black (Special Black4: Degussa) 10 parts NMP solvent 100 parts where X is 0.1, 0.125, 1, 2.5 in Reference Examples 3-7, respectively 3.
Using the dispersant used in Reference Example 2 , a carbon black dispersion was prepared in the same manner and evaluated in the same manner. The evaluation results are shown in [Table 3] below.

[Reference Examples 8 to 12]
The carbon black dispersion component used in Reference Example 2 was ball mill stirred in the same manner except for the stirring time.
The results of stirring time and particle size are shown in [Table 4] below.

[Examples 13 and 14]: ( Corresponding to Claims 1 and 2 )
(Carbon black dispersion component)
Dispersant 1.5 parts by weight carbon black (Special Black4: manufactured by Degussa) 10 parts by weight NMP solvent 100 parts by weight The following were used as dispersants.
Example 13
Silicone modified polyimide (SMP3002: manufactured by Shin-Etsu Chemical Co., solid content: 40 wt%) 1.2 parts by weight of polyimide varnish (a polyamic acid solution, U Varnish S: manufactured by Ube Industries, Ltd., solid content: 18 wt%) 0.3 parts by weight Example 14
Silicone modified polyimide (SMP3002: Shin-Etsu Chemical Co., Ltd., solid content 40 wt%) 1.2 parts by weight of polyimide varnish (a polyamic acid solution, U Varnish A: manufactured by Ube Industries, Ltd., solid content: 18 wt%) 0.3 parts by weight of these In the same manner as in Reference Example 2 above, a carbon black dispersion was prepared.
Moreover, the film-forming liquid was produced using each carbon black dispersion liquid.
(Deposition liquid component)
Carbon black dispersion 20 parts by weight polyimide varnish (U varnish A: Ube Industries: solid content 18 wt%) 40 parts by weight

For comparison, a film forming solution was similarly prepared using the carbon black dispersion of Reference Example 2 .
The measurement results of the particle sizes of the carbon black dispersion and the film forming solution are shown in Table 5 below.

[Reference Example 15, Example 16]: (Example 16 corresponds to claim 3)
After applying dipping coating on a SUS roller (10 mmφ) using the film forming liquid of Reference Example 2 and Example 14 , predetermined drying conditions (primary drying temperature: 120 ° C., primary drying temperature) : 350 ° C.) to prepare a roller having a carbon-dispersed polyimide resin layer having a thickness of 10 μm.
The volume resistance of this roller was measured at 10 locations, and the average resistance and variation (Logmax resistance−Logmin resistance) were calculated.
The allowable range of variation is preferably within one digit, and most preferably within 0.5 digit.
The calculation results are shown in [Table 6] below.

[Embodiment 17]: ( Corresponding to Claim 4 )
Using the film forming solution of Example 14, an endless belt was produced by the centrifugal molding method described above. However, the drying conditions are the same as in Example 16 .
The endless belt has a film thickness of 78 μm and an outer diameter of 360 mmφ.
The average resistance and variation (Logmax resistance-Logmin resistance) were calculated in the same manner as in Example 16 .
The allowable range of the endless belt variation is the same as that of the sixteenth embodiment .
The calculation results are shown in [Table 7] below.

[Embodiment 18]: ( Corresponding to Claim 5 )
The endless belt produced in Example 17 was attached to the image forming apparatus shown in FIG. 3, and the halftone image density to be formed was adjusted to approximately 0.8.
About the obtained halftone image, the degree of occurrence of a blurred image, which is a spot-like density unevenness, was evaluated.
With respect to the obtained halftone image, the degree of occurrence of a blurred image that is spotted density unevenness was evaluated.
◎: Very good ◯: Good △: No problem in actual use ×: Very bad Evaluation of the endless belt produced in Example 17 gave ◎: very good results, and the endless belt of the present invention As a result, it was found that the image forming apparatus equipped with is sufficiently excellent in practical use in evaluating density unevenness and image quality.

FIG. 1 shows a schematic diagram of a main part of an example of a tandem type electrophotographic apparatus. FIG. 2 is a schematic view of a main part of another example of a tandem type electrophotographic apparatus. 1 is a schematic configuration diagram of a tandem type indirect transfer type electrophotographic apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Transfer apparatus 3 Sheet conveyance belt 4 Intermediate transfer body 5 Secondary transfer apparatus 6 Paper feed apparatus 7 Fixing apparatus 8 Photoconductor cleaning apparatus 9 Intermediate transfer body cleaning apparatus 10 Endless belt-shaped intermediate transfer body 14 First support Roller 15 Second support roller 16 Third support roller 17 Intermediate transfer member cleaning device 18 Image forming means 20 Tandem image forming device 21 Exposure device 22 Secondary transfer device 23 Roller 24 Secondary transfer belt 25 Fixing device 26 Fixing belt 27 Pressure roller 28 Sheet reversing device 100 Copier main body 200 Paper feed table 300 Scanner 400 Automatic document feeder (ADF)

Claims (5)

  A carbon black dispersion liquid comprising at least carbon black subjected to surface treatment with a silicone-modified polyimide and a polyamic acid solution, and a dispersion medium. Even without least includes carbon black dispersion according to claim 1, polyamic acid solution is separately added,
A polyimide resin film forming solution, wherein the polyamic acid solution used for the surface treatment and the separately added polyamic acid solution are made of the same material. A roller, wherein a resin layer made of a polyimide resin obtained by applying an imidization treatment after applying the polyimide resin film-forming solution according to claim 2 is formed on at least the surface. An endless belt, wherein a resin layer made of a polyimide resin obtained by applying an imidization treatment after applying the polyimide resin film-forming solution according to claim 2 is formed on at least the surface. At least a charging device that forms an electrostatic latent image on the image carrier;
A developing device that forms a toner image on the image carrier using a developer corresponding to a desired color;
An intermediate transfer device that sequentially superimposes and temporarily transfers the toner image on an endless intermediate transfer body, and temporarily transfers the temporary transfer image on the intermediate transfer body onto a transfer material;
An image forming apparatus comprising: a fixing device that heats or pressurizes a toner image on the transfer material to fix the toner image on the transfer material;
At least one of a roller and an endless belt constituting each of the charging device, the developing device, the intermediate transfer device, and the fixing device is subjected to imidization treatment after applying the polyimide resin film forming solution according to claim 2. An image forming apparatus, wherein a resin layer made of a polyimide resin obtained by applying is formed on at least a surface.

Images