JP2019138999A - Intermediate transfer belt, method for manufacturing the same, and image forming apparatus - Google Patents

Abstract

To provide an intermediate transfer belt that produces a small amount of deterioration in image quality even under high temperature and high humidity, a method for manufacturing the same, and an image forming apparatus provided with the same.SOLUTION: The intermediate transfer belt is used for an image forming apparatus of an electrophotographic system, and contains polyimide or polyamide imide, a dispersant having a carboxyl group and an amino group, and acidic carbon black.SELECTED DRAWING: None

Description

  The present invention relates to an intermediate transfer belt, a manufacturing method thereof, and an image forming apparatus. More specifically, the present invention relates to an intermediate transfer belt with little deterioration in image quality even under high temperature and high humidity, a manufacturing method thereof, and an image forming apparatus including the intermediate transfer belt.

  Conventionally, as an electrophotographic image forming apparatus using an intermediate transfer belt, a toner image formed on a photoconductor is transferred to an intermediate transfer belt, and the toner image on the intermediate transfer belt is transferred paper (recording paper) or the like. Those that are transferred to other transfer materials are known. That is, after a toner image formed on a photoconductor charged to a predetermined polarity is transferred to an intermediate transfer belt using electrostatic force, the toner image on the intermediate transfer belt is transferred to the transfer material using electrostatic force. Transfer on top.

  In such an image forming apparatus using an intermediate transfer belt, electrostatic images are used to sequentially superimpose toner images formed on the respective photoreceptors on the intermediate transfer belt, and further, the superimposed toner images are used as a transfer material. Since batch transfer is possible, it is widely used as a color image forming apparatus.

  In general, the intermediate transfer belt is obtained by adding carbon black dispersed as a conductive filler to polyimide or polyamide-imide having excellent mechanical properties, electrical insulation, and heat resistance in order to adjust electrical resistance.

  However, polyimide and polyamideimide have many hydrophilic groups in the molecular structure and have high water absorption. In addition, the dispersant used to disperse the carbon black in the intermediate transfer belt is also hygroscopic. Therefore, the intermediate transfer belt absorbs moisture under high temperature and high humidity, and the electric resistance is lowered. As a result, the charge of the toner leaks to the intermediate transfer belt, and the transfer unevenness increases.

  In order to stabilize the electric resistance of the intermediate transfer belt, Patent Document 1 discloses that by improving the dispersibility of the conductive fine particles, it has a stable surface resistance value and is less likely to cause density unevenness and spotted defects. Is disclosed. However, in particular, it has not been sufficient in improving transfer unevenness under high temperature and high humidity.

JP 2007-219137 A

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems and situations, and a solution to the problem is to provide an intermediate transfer belt with little deterioration in image quality even under high temperature and high humidity, a method for manufacturing the same, and an image forming apparatus including the intermediate transfer belt. It is.

  In order to solve the above-mentioned problems, the present inventor uses a dispersant having a carboxy group and an amino group as a dispersant for acidic carbon black in the course of studying the cause of the above-described problem, thereby making the hydrophilic property of the intermediate transfer belt. As a result, the present invention has been found to improve the transfer unevenness under high humidity.

  That is, the said subject which concerns on this invention is solved by the following means.

1. An intermediate transfer belt used in an electrophotographic image forming apparatus,
Polyimide or polyamideimide,
An intermediate transfer belt comprising a dispersant having a carboxy group and an amino group and acidic carbon black.

  2. 2. The intermediate transfer belt according to claim 1, wherein the dispersant contains a block copolymer having a block body having a carboxy group and a block body having an amino group.

  3. 3. The intermediate transfer belt according to item 1 or 2, wherein the dispersant has a weight average molecular weight Mw in the range of 10,000 to 20,000.

4). An intermediate transfer belt manufacturing method for manufacturing the intermediate transfer belt according to any one of items 1 to 3,
After preparing a carbon black dispersion in which the acidic carbon black is dispersed in advance with a dispersant having the carboxy group and the amino group, the carbon black dispersion and the polyimide precursor or polyamideimide are mixed. An intermediate transfer belt manufacturing method characterized by the above.

  5. An image forming apparatus comprising the intermediate transfer belt according to any one of Items 1 to 3.

  By the above-mentioned means of the present invention, it is possible to provide an intermediate transfer belt with little deterioration in image quality even under high temperature and high humidity, a manufacturing method thereof, and an image forming apparatus equipped with the intermediate transfer belt.

  The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

  By using a dispersant having a carboxy group and an amino group as a dispersant for acidic carbon black, the amino group in the dispersant is adsorbed on the carboxy group or sulfo group present on the surface of the acidic carbon black, thereby dispersing the carbon black. Stability is ensured. On the other hand, the carboxy group not adsorbed on the carbon black in the dispersing agent is bonded to the amino group at the end of the polyimide or polyamideimide by a condensation reaction. For this reason, the dispersant becomes high molecular weight while maintaining the dispersion state of carbon black, and the hydrophilicity is lowered.

  When a dispersant having an amino group and a dispersant having a carboxy group are added, gelation occurs due to the action of an acid and a base and the dispersibility is lowered. However, by having an amino group and a carboxy group in one molecule, the amino group is adsorbed on the carbon black, and the carboxy group is repelled from the carbon black, whereby gelation can be suppressed.

  Moreover, since the terminal functional group of polyamide or polyamideimide also decreases, it is thought that hydrophilicity falls. Therefore, it is presumed that, even under high temperature and high humidity, the moisture transfer of the intermediate transfer belt is suppressed, so that the decrease in electrical resistance is suppressed and transfer unevenness is improved.

Conceptual sectional view showing an example of a layer structure of the intermediate transfer belt 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus that can use an intermediate transfer belt according to the present invention.

  The intermediate transfer belt of the present invention is an intermediate transfer belt used for an electrophotographic image forming apparatus, and includes polyimide or polyamideimide, a dispersant having a carboxy group and an amino group, and acidic carbon black. To do. This feature is a technical feature common to or corresponding to each of the following embodiments.

  As an embodiment of the present invention, the dispersant contains a block copolymer having a block body having a carboxy group and a block body having an amino group, so that the functional group of the dispersant is functionally separated. It is preferable because a great effect can be exhibited.

  Moreover, the weight average molecular weight Mw of the said dispersing agent exists in the range of 10000-20000 can suppress the thermal decomposition of the dispersing agent in the process of promoting the imidation of the polyimide precursor mentioned later, and carbon black Aggregation can be suppressed, and uniformity of resistance is maintained, which is preferable.

  As an intermediate transfer belt manufacturing method for manufacturing the intermediate transfer belt of the present invention, a carbon black dispersion in which the acidic carbon black is dispersed in advance with a dispersant having the carboxy group and the amino group is prepared. From the viewpoint of improving the stability of the dispersant, it is preferable to have a step of mixing the dispersion and the polyimide precursor or polyamideimide.

  The intermediate transfer belt of the present invention can be suitably provided in an image forming apparatus.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<Intermediate transfer belt>
The intermediate transfer belt of the present invention is an intermediate transfer belt used for an electrophotographic image forming apparatus, and includes polyimide or polyamideimide, a dispersant having a carboxy group and an amino group, and acidic carbon black. To do.

  FIG. 1 is a conceptual cross-sectional view showing an example of the layer configuration of the intermediate transfer belt. In FIG. 1, 1 is an intermediate transfer belt, 2 is a substrate, 3 is an elastic layer, and 4 is a surface layer. The intermediate transfer belt of the present invention may be composed of only the base material, but if necessary, it may be configured to have layers such as an elastic layer or a surface layer in this order on the base material.

The thickness of the intermediate transfer belt can be appropriately determined according to the purpose of use and the like, but generally it is preferably 50 to 500 [mu] m, more preferably 200 to 400 [mu] m, which satisfies mechanical properties such as strength and flexibility. Further, it is preferable that the electric resistance value (volume resistivity) of the intermediate transfer belt is in the range of 10 ⁵ to 10 ¹¹ Ω · cm.

  The shape of the intermediate transfer belt is such that the endless intermediate transfer belt has no thickness change due to superposition, and an arbitrary part can be set as the belt rotation start position, and the rotation start position control mechanism can be omitted. It is preferable.

"Base material"
The intermediate transfer belt of the present invention can be composed of only a substrate. The base material contains polyimide or polyamideimide, a dispersant having a carboxy group and an amino group, and acidic carbon black. As the base material, polyimide or polyamideimide is used in the range of the use temperature of the intermediate transfer belt because of rotation under high tension, high voltage load, ozone resistance and the like in the image forming apparatus.

The substrate preferably has an electric resistance value (volume resistivity) in the range of 10 ⁵ to 10 ¹¹ Ω · cm. In order to make the electrical resistance value of the base material within a predetermined range, the base material contains at least acidic carbon black as a conductive substance. Moreover, it is preferable that the thickness of a base material exists in the range of 50-500 micrometers, and the inside of the range of 200-400 micrometers is more preferable. Furthermore, you may add various well-known additives to a base material.

[Polyimide or polyamideimide]
A polyimide can be obtained via a precursor because the precursor is dissolved in an organic solvent at a high concentration and can be easily formed into a film together with additives and the like. A polyimide precursor or a polyamideimide precursor and a polyimide or polyamideimide produced by heat treatment (imidization) of the precursor will be described in detail.

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

(In the formula, Ar ¹ represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and Ar ² represents a divalent aromatic residue containing at least one carbon 6-membered ring.)
Specific examples of the aromatic polycarboxylic 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-dicarboxyphenyl) -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 are used individually or in mixture of 2 or more types.

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

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

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

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

  In the present invention, the polyimide precursor solution (polyamic acid solution) can be synthesized as described above, but in a state where the polyamic acid composition is simply dissolved in an organic solvent, What is marketed as what is called 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), Rika Coat (manufactured by Nippon Nippon Chemical Co., Ltd.), Optmer (manufactured by JSR), SE812 (manufactured by Nissan Chemical Industries), CRC8000 (Manufactured by Sumitomo Bakelite Co., Ltd.) is a typical example.

  A carbon black dispersion and various additives are mixed and dispersed in the synthesized or obtained polyamic acid solution, and additives are added and mixed as necessary to prepare a coating solution. After applying the coating liquid to a support (molding mold) as described later, the conversion (imidation) from polyamic acid, which is a precursor of polyimide, to polyimide can be performed by treatment such as heating. it can.

  That is, the polyamic acid can be imidized by a heating method (1) or a chemical method (2). The heating method (1) is a method for converting polyamic acid to polyimide by heat treatment at 300 to 400 ° 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 preferable because the method is more complicated and costly than the method (2).

  In order to exhibit the intrinsic performance of polyimide, it is necessary 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 field calculated from an integral ratio of ¹ H attributed to an amide group in the vicinity of 9 to 11 ppm and ¹ H attributed to an aromatic ring in the vicinity of 6 to 9 ppm. Various methods such as resonance spectroscopy (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. Among them, Fourier transform infrared spectroscopy (FT-IR method) is the most common method.

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

  That is, assuming that (A) is the number of moles of imide groups at the firing stage (imidation treatment stage) and (B) is the number of moles of imide groups when 100% imidized (theoretical), Is done.

Imidation rate = [(A)) / (B))] × 100
The number of moles of the imide group in this definition can be determined from the absorbance ratio of the characteristic absorption of the imide group measured by the FT-IR method. For example, as a typical characteristic absorption, the imidization ratio can be evaluated using the following absorbance ratio.

(1) Absorbance ratio of 725 cm ⁻¹ (immobilization band of imide ring C═O group) which is one of characteristic absorption of imide and benzene ring characteristic absorption of 1015 cm ⁻¹ (2) Characteristic absorption of imide Absorbance ratio between 1380 cm ⁻¹ (inflection band of imide ring C—N group) and characteristic absorption 1500 cm ^{−1 of} benzene ring (3) 1720 cm ⁻¹ (one of characteristic absorption of imide) Absorbance ratio between imide ring C = O group bending vibration band) and benzene ring characteristic absorption 1500 cm ^-1 (4) 1720 cm ^-1 which is one of imide characteristic absorption and amide group characteristic absorption 1670 cm ^-1 Absorbance ratio with (interaction between amide group N—H bending vibration and C—N stretching vibration) Also confirm that the multiple absorption band derived from the amide group from 3000 to 3300 cm ⁻¹ has disappeared. Bye Reliability of the imidization completion 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.

  In general, 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 Examined 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, a compound having a structure represented by the following general formula (1) and general formula (2) is used. Can do.

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

General formula (2)
(In the formula, X represents a halogen element. Y represents —CH ₂ —, —CO—, —SO ₂ — or —O—).
In each of the above formulas, the halogen element is preferably chlorine, and specific examples of derivatives include terephthalic acid, isophthalic acid, 4,4′biphenyldicarboxylic acid, 4,4′biphenyletherdicarboxylic acid, and 4,4′biphenylsulfonedicarboxylic 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, Examples thereof include acid chlorides of polyvalent carboxylic acids such as 3 ′, 4,4′biphenyltetracarboxylic acid.

  These compounds can be used alone or in combination. As necessary, as part of these, acids of polyvalent carboxylic acids such as adipic acid, sebacic acid, maleic acid, fumaric acid, dimer acid, stilbene dicarboxylic acid, 1,4 cyclohexanedicarboxylic acid, 1,2 cyclohexanedicarboxylic acid Chloride can be used.

  On the other hand, although it does not specifically limit as diamine, Although aromatic diamine, aliphatic diamine, and alicyclic diamine are all used, aromatic diamine is used preferably.

  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) hexafluoropropane 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 A , Isopropylidenedianiline, 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 Hexafluoropropane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide and the like.

  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, 1, 3-bis (3- (3-aminophenoxy) propyl) -1,1,3,3-tetramethyldisiloxane, α, ω-bis (3- (3-aminophenoxy) propyl ) Silicone-modified polyamideimide can be obtained by using polydimethylsiloxane or the like.

  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.

  The polyamide / polyamic acid solution obtained above may be mixed with the carbon black dispersion according to the present invention or various known additives to prepare a coating solution. After the coating liquid is applied to the support (molding die), the polyamic acid is converted to polyimide (imidation) 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 300 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. It is. 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. It is. 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 a derivative of a trivalent carboxylic acid having an acid anhydride group used in the isocyanate method, for example, a compound having a structure represented by the following general formula (3) or the following general formula (4) Can be used.

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

(In the formula, R represents hydrogen, an alkyl group having 1 to 10 carbon atoms, or a phenyl group. Y represents —CH ₂ —, —CO—, —SO ₂ —, or —O—).
Any derivative having the above general formula can be used, but preferred is trimellitic anhydride. These trivalent carboxylic acid derivatives having an acid anhydride group may 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 part of this as required Aliphatic such as isocyanate and lysine diisocyanate, alicyclic isocyanate and trifunctional or higher polyisocyanate can also be used.

  The carbon black dispersion according to the present invention is dispersed in a solution containing a polyamideimide precursor obtained by adjusting the trivalent carboxylic acid derivative having each acid anhydride group and an aromatic polyisocyanate in an organic polar solvent. You may prepare a coating liquid by mixing a liquid and well-known various additives. After the coating liquid is applied to the support, the polyamideimide precursor is converted to polyamideimide by heat treatment. Upon conversion to polyamideimide by this method, polyamideimide is generated without generating a carbonic acid (generally generating carbon dioxide). The following reaction formula (II) shows an example of polyamide imidization when trimellitic anhydride and aromatic isocyanate are used.

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

  Furthermore, when polyamideimide is used as a base material, polyamideimide has a high solubility in an organic polar solvent, unlike polyimide. Therefore, the carbon black dispersion according to the present invention and various known additives are added to the polyamideimide solution. A coating solution can be prepared by mixing. The organic polar solvent mentioned above can be used for a solvent.

  The above-described polyimide or polyamideimide is used for the substrate of the present invention. Polyimide alone may be used as the resin, but it is also possible to use a mixture of polyimide and polyamideimide. In this case, the mass ratio of polyimide: polyamideimide is preferably in the range of 100: 0 to 50:50.

  Other base materials include polyimide, polyamideimide, polycarbonate, polyphenylene sulfide, polyvinylidene fluoride, polyalkylene terephthalate (polyethylene terephthalate, polybutylene terephthalate, etc.), polyether, polyether ketone, polyether ether ketone. An ethylene tetrafluoroethylene copolymer may be used. In this case, the content of polyimide, polyamideimide or the total content thereof in the base material is preferably 51% by mass or more, more preferably 90% by mass with respect to the total resin, and all are polyimide or polyamideimide. Is more preferable.

[Dispersant]
The dispersant according to the present invention has a carboxy group and an amino group. This dispersant is preferably a copolymer of a monomer having a carboxy group and a monomer having an amino group. The dispersing agent is a block copolymer having a block body having a carboxy group and a block body having an amino group, rather than a copolymer obtained by randomly polymerizing a monomer having a carboxy group and a monomer having an amino group. More preferably.

(Monomer having a carboxy group)
Since the dispersant according to the present invention has a carboxy group, when acidic carbon black is dispersed, the carboxy group not adsorbed on the carbon black in the dispersant is subjected to a condensation reaction with an amino group at the end of polyimide or polyamideimide. Join. For this reason, it is considered that the hydrophilicity is lowered because the dispersant has a high molecular weight and the hydrophilicity is lowered while the terminal functional groups of polyamide and polyamideimide are also reduced while maintaining the dispersion state of carbon black.

  Specific examples of the monomer having a carboxy group include acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, itaconic acid, citraconic acid, cinnamic acid, succinic acid monohydroxyethyl (meth) acrylate, maleic acid Monohydroxyethyl (meth) acrylate, monohydroxyethyl fumarate (meth) acrylate, phthalate monohydroxyethyl (meth) acrylate, 1,2-dicarboxycyclohexane monohydroxyethyl (meth) acrylate, (meth) acrylic acid dimer, ω-carboxy-polycaprolactone mono (meth) acrylate.

  Of these, acrylic acid and methacrylic acid are preferable.

  It is preferable that the structural unit derived from the monomer which has a carboxy group in the dispersing agent which concerns on this invention exists in the range of 10-90 mol% with respect to all the structural units in a polymer.

  The structural unit derived from the monomer having a carboxy group in the dispersant may be one type or two or more types.

(Monomer having an amino group)
It is considered that the dispersant according to the present invention has an amino group, so that the carboxyl group or sulfo group present on the surface of the acidic carbon black is adsorbed by the amino group in the dispersant, and the dispersion stability of the carbon black is ensured. It is done.

  The monomer having an amino group is preferably a vinyl monomer having an amino group. The vinyl monomer having an amino group can be used without any particular limitation. Further, a quaternized vinyl monomer may be used. These may be used alone or in combination of two or more.

  For example, the vinyl monomer which has a primary amino group can be mentioned. Specific examples include acrylamide, methacrylamide, 4-vinylaniline, aminomethyl (meth) acrylate, aminoethyl (meth) acrylate, aminopropyl (meth) acrylate, aminobutyl (meth) acrylate, and the like.

  Moreover, the vinyl monomer which has a secondary amino group can be mentioned. Specifically, anilinostyrene, β-phenyl-p-anilinostyrene, β-cyano-p-anilinostyrene, β-cyano-β-methyl-p-anilinostyrene, β-chloro-p-anis Linostyrene, β-carboxy-p-anilinostyrene, β-methoxycarbonyl-p-anilinostyrene, β- (2-hydroxyethoxy) carbonyl-p-anilinostyrene, β-formyl-p-anilinostyrene, Anilinostyrenes such as β-formyl-β-methyl-p-anilinostyrene, α-carboxy-β-carboxy-β-phenyl-p-anilinostyrene, 1-anilinophenyl-1,3-butadiene, 1-anilinophenyl-3-methyl-1,3-butadiene, 1-anilinophenyl-3-chloro-1,3-butadiene, 3-anilinophenyl-2-methyl Til-1,3-butadiene, 1-anilinophenyl-2-chloro-1,3-butadiene, 2-anilinophenyl-1,3-butadiene, 2-anilinophenyl-3-methyl-1,3- Anilinophenylbutadienes such as butadiene and 2-anilinophenyl-3-chloro-1,3-butadiene, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methylolacrylamide, N- (4 And N-monosubstituted (meth) acrylamides such as -anilinophenyl) methacrylamide.

  Furthermore, examples of the vinyl monomer having a tertiary amino group include N, N-disubstituted aminoalkyl (meth) acrylate and N, N-disubstituted aminoalkyl (meth) acrylamide.

  Examples of the N, N-disubstituted aminoalkyl (meth) acrylate include N, N-dimethylaminomethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, and N, N-dimethylaminopropyl (meth). Acrylate, N, N-dimethylaminobutyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-diethylaminopropyl (meth) acrylate, N, N-diethylaminobutyl (meth) acrylate, N-methyl -N-ethylaminoethyl (meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate, N, N-dibutylaminoethyl (meth) acrylate, N, N-dibutylaminopropyl (meth) acrylate, N, N-dibutylaminobutyl (meth) acrylate, N, N- Examples thereof include esters of acrylic acid or methacrylic acid such as dihexylaminoethyl (meth) acrylate, N, N-dioctylaminoethyl (meth) acrylate, and acryloylmorpholine.

  Among these, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dipropylaminoethyl (meth) acrylate, N, N-dioctylaminoethyl (meth) Acrylate, N-methyl-N-ethylaminoethyl (meth) acrylate and the like are particularly preferable.

  Examples of the N, N-disubstituted aminoalkyl (meth) acrylamide include N, N-dimethylaminomethyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl ( (Meth) acrylamide, N, N-dimethylaminobutyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide, N, N-diethylaminobutyl (meth) acrylamide, N -Methyl-N-ethylaminoethyl (meth) acrylamide, N, N-dipropylaminoethyl (meth) acrylamide, N, N-dibutylaminoethyl (meth) acrylamide, N, N-dibutylaminopropyl (meth) acrylamide, N, N-dibutylaminobuty Acrylamide compounds such as (meth) acrylamide, N, N-dihexylaminoethyl (meth) acrylamide, N, N-dihexylaminopropyl (meth) acrylamide, N, N-dioctylaminopropyl (meth) acrylamide, or methacrylamide compounds Can be mentioned.

  Among these, N, N-dimethylaminopropyl (meth) acrylamide, N, N-diethylaminopropyl (meth) acrylamide, N, N-dioctylaminopropyl (meth) acrylamide and the like are particularly preferable.

  The above “(meth) acrylate” is a general term for “acrylate” and “methacrylate”.

  Furthermore, it is preferable that a dispersing agent contains the partial structure (monomer unit) represented by following General formula (5).

(In the formula, R ⁴ represents a hydrogen atom or a methyl group. R ⁵ represents an alkylene group having 1 to 10 carbon atoms. R ⁶ and R ⁷ each independently represents a hydrogen atom or a carbon number. Represents an alkyl group of 1 to 10.)
Specific examples of the alkylene group having 1 to 10 carbon atoms represented by R ⁵ include alkylene groups such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a pentamethylene group, a hexamethylene group, and a heptamethylene group. Is mentioned. R ⁵ is preferably an alkylene group having 1 to 5 carbon atoms.

Specific examples of the alkyl group having 1 to 10 carbon atoms represented by R ⁶ and R ⁷ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a sec-butyl group. , A tert-butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl group, a linear alkyl group such as a decyl group. R ⁶ and R ⁷ are preferably each independently a hydrogen atom or an alkyl group having 1 to 5 carbon atoms.

  A plurality of types of monomers may be used as the monomer having an amino group.

  In the dispersant according to the present invention, the structural unit derived from the monomer having an amino group is preferably in the range of 10 to 90 mol% with respect to all the structural units in the polymer.

  The dispersant according to the present invention may have a structural unit derived from another monomer as long as the effects of the present invention are not impaired.

  The polymerization reaction is performed by a known method.

(Block copolymer)
The dispersant according to the present invention is more preferably a block copolymer having a block body A having a carboxy group and a block body B having an amino group. By constituting the dispersant with a block polymer, the functional group of the dispersant is functionally separated, and a greater effect can be exhibited.

  When a dispersant having an amino group and a dispersant having a carboxy group are added, gelation occurs due to the action of an acid and a base, resulting in a decrease in dispersibility. However, since an amino group and a carboxy group are included in one molecule, the amino group is carbon. Gelation can be suppressed by adsorbing to black and repelling the carboxy group with carbon black. The effect is more prominent than in the case of a block copolymer.

  In the block copolymer, the molar ratio of block A to block B (A block: B block) is preferably in the range of 10:90 to 90:10, and in the range of 40:60 to 60:40. More preferably, it is within.

  The method for producing the block copolymer is not particularly limited. The block copolymer can be obtained, for example, by sequentially polymerizing monomers by block polymerization using a living radical polymerization method or the like. The block body A may be produced first by the polymerization reaction of the monomers, and the block body B monomer may be polymerized to the block body A, or the block body B may be produced first and the block body B may be polymerized with the block body A monomer. May be polymerized. Moreover, in manufacture of a block copolymer, after manufacturing the block body A and the block body B separately by the polymerization reaction of a monomer, the block body A and the block body B may be coupled.

  The block copolymer is preferably a diblock copolymer composed of a block body A and a block body B. Usually, (block body A)-(block body B), (block body B)-(block body A) ). The living radical polymerization method is a polymerization method that enables precise control of the molecular structure while maintaining the simplicity and versatility of radical polymerization. The living radical polymerization method includes a method using a transition metal catalyst (ATRP), a method using a sulfur-based reversible chain transfer agent (RAFT), and a method using an organic tellurium compound depending on the method for stabilizing the polymerization growth terminal. There are methods such as (TERP). Among these methods, a method using an organic tellurium compound described in International Publication Nos. 2004/14848 and 2004/14962 from the viewpoint of diversity of usable monomers and molecular weight control in the polymer region. (TERP) is preferably used.

  The weight average molecular weight Mw of the dispersant according to the present invention is preferably in the range of 10,000 to 20,000. If it is 10,000 or more, thermal decomposition of the dispersant can be suppressed in the baking step (300 to 400 ° C.) in which dehydration and cyclization is performed by heat treatment to form a polyimide or polyamide-imide, aggregation of carbon black can be suppressed, and resistance is uniform. Sex is maintained. Moreover, it is preferable that it is 20000 or less from a soluble viewpoint as a carbon black dispersion liquid.

  If it is in this range, it is further preferable that the weight average molecular weight Mw of the dispersant is in the range of 10,000 to 20,000.

  The weight average molecular weight Mw can be measured by gel permeation chromatography. An example of the measurement conditions is as follows.

Solvent: Dichloromethane Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 mL / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) Mw = 500 to 2800000 calibration curves with 13 samples are used. The 13 samples are preferably used at approximately equal intervals.

[Acid carbon black]
In the present invention, acidic carbon black having a pH value of less than 7.0 is used. The acidic carbon black may be added so that the volume resistance value and the surface resistance value of the intermediate transfer member are in a desired range. Usually, it may be added within a range of 10 to 20 parts by mass with respect to 100 parts by mass of the resin, and preferably within a range of 10 to 16 parts by mass with respect to 100 parts by mass of the resin.

  As the conductive agent in the present invention, good dispersibility and dispersion stability in the resin composition (resin component) can be obtained, resistance variation of the semiconductive belt can be reduced, and electric field dependency is also small. Further, acidic carbon black having a pH of 5.0 or less is preferably used from the viewpoint of improving the stability of electric resistance over time without causing electric field concentration due to a transfer voltage.

  The acidic carbon black having a pH of 5.0 or less can be produced by oxidizing the carbon black to give a carboxy group, a quinone group, a lactone group, a hydroxy group, or the like to the surface. This oxidation treatment is an air oxidation method in which contact is made with air in a high-temperature atmosphere to react, a method of reacting with nitrogen oxides or ozone at room temperature, and air oxidation at high temperature, followed by ozone oxidation at a low temperature. It can be performed by a method or the like. Specifically, acidic carbon black having a pH of 5.0 or less can be produced by a contact method. Examples of the contact method include a channel method and a gas black method.

  Moreover, acidic carbon black can also be manufactured by the furnace black method which uses gas or oil as a raw material. Further, if necessary, after performing these treatments, a liquid phase oxidation treatment with nitric acid or the like may be performed. Although acidic carbon black can be produced by the contact method as described above, it is usually produced by a closed furnace method. In this furnace method, only carbon black having a high pH and a low volatile content is usually produced, but the pH value can be adjusted by applying the above-described liquid phase oxidation treatment thereto.

  The pH value of the acidic carbon black in the present invention is preferably pH 5.0 or less, more preferably 4.5 or less, and even more preferably pH 4.0 or less. Acidic carbon having a pH of 5.0 or less has an oxygen-containing functional group such as a carboxy group, a hydroxy group, a quinone group, and a lactone group on the surface, so that the dispersibility in the resin is good and good dispersion stability is obtained. The resistance variation of the semiconductive belt can be reduced, and the electric field dependency is also reduced, so that electric field concentration due to the transfer voltage hardly occurs. The lower limit value of the pH value of the acidic carbon black is about 2.0.

  The acidic carbon black having a pH of 5.0 or less preferably has a volatile component content in the range of 1 to 25% by mass, more preferably 3 to 20% by mass, and 3.5 to 15% by mass. More preferably, it is contained in the range of%. When the content of the volatile component is less than 1% by mass, the effect of the oxygen-containing functional group attached to the surface is lost, and the dispersibility to the resin component may be reduced. On the other hand, when the content of the volatile component is higher than 25% by mass, it may be decomposed when dispersed in the resin composition, or the amount of water adsorbed on the oxygen-containing functional group on the surface may increase. The appearance of the belt surface in the present invention may deteriorate.

  On the other hand, the dispersion | distribution in the said resin composition can be made more favorable by making content of the said volatile component into the range of 1-25 mass%. The content of the volatile component can be determined from the ratio of organic volatile components (carboxy group, hydroxy group, quinone group, lactone group, etc.) that come out when carbon black is heated at 950 ° C. for 7 minutes. .

  Specific examples of acidic carbon black having a pH of 5.0 or less include “Printex 150T” (pH 4.5, volatile content 10.0% by mass) and “Special Black 350” (pH 3.5, volatile) manufactured by Degussa. 2.2% by mass), “Special Black 100” (pH 3.3, volatile content 2.2% by mass), “Special Black 250” (pH 3.1, volatile content 2.0% by mass), “ Special Black 5 ”(pH 3.0, volatile content 15.0% by mass),“ Special Black 4 ”(pH 3.0, volatile content 14.0% by mass),“ Special Black 4A ”(pH 3.0, volatile) 14.0% by mass), “Special Black 550” (pH 2.8, volatile content 2.5% by mass), “Special Black 6” (pH 2.5, volatile content 18.0% by mass), “ Carabu FW200 "(pH 2.5, volatile content 20.0% by mass)," Color Black FW2 "(pH 2.5, volatile content 16.5% by mass)," Color Black FW2V "(pH 2.5, volatile) 16.5% by mass), “MONARCH1000” manufactured by Cabot (pH 2.5, volatile content 9.5% by mass), “MONARCH 1300” manufactured by Cabot (pH 2.5, volatile content 9.5% by mass), Cabot Corporation “MONARCH1400” (pH 2.5, volatile matter 9.0% by mass), “MOGUL-L” (pH 2.5, volatile matter 5.0% by mass), “REGAL400R” (pH 4.0, volatile matter 3) 0.5 mass%) and the like.

  The acidic carbon black having a pH of 5.0 or less is more conductive than the general carbon black because it has better dispersibility in the resin composition due to the effect of the oxygen-containing functional group present on the surface as described above. It is preferable to increase the addition amount as a powder. Thereby, since the amount of conductive particles in the semiconductive belt increases, the effect of using acidic carbon black, such as being able to suppress the in-plane variation of the electrical resistance value, can be maximized. it can.

  The pH measurement of carbon black can be performed according to the following procedure. 3 g of carbon black is added to 20 g of distilled water (pH 6.8 to 7.2), and after stirring for 5 minutes, the hydrogen ion concentration at a liquid temperature of 25 ° C. is measured with a glass electrode using, for example, HM50S (manufactured by Toa DKK Corporation). . A pH of less than 7.0 was acidic carbon black, and 7.0 or higher was basic carbon black.

≪Elastic layer≫
The elastic layer is a layer having desired conductivity and elasticity that can be formed on the outer peripheral surface of the base material as necessary. The elastic layer is made of a rubber material. The thickness of the elastic layer is, for example, 50 to 400 μm. Examples of the rubber material include resins having rubber elasticity such as urethane rubber, chloroprene rubber (CR), and nitrile rubber (NBR). The rubber material preferably contains chloroprene rubber or nitrile butadiene rubber from the viewpoint of controlling the electric resistance of the intermediate transfer belt.

Both the base material and the elastic layer may further contain a conductive agent in order to express the desired conductivity. As the conductive agent, a known material for imparting conductivity to the resin material of the intermediate transfer member is used. One or more conductive agents may be used. Examples of the conductive agent include an ionic conductive agent and an electronic conductive agent. Examples of ionic conductive agents include silver iodide, copper iodide, lithium perchlorate, lithium perchlorate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium salt of an organic boron complex, lithium bisimide ((CF ₃ SO ₂ ) ₂ NLi) and lithium trismethide ((CF ₃ SO ₂ ) ₃ CLi). Examples of the electronic conductive agent include metals such as silver, copper, aluminum, magnesium, nickel, and stainless steel; and carbon compounds such as graphite, carbon black, and carbon nanofiber carbon nanotubes. The total content of the conductive agent in the base material and the elastic layer is an amount that realizes the desired volume resistivity of the intermediate transfer belt.

<Surface layer>
If necessary, the surface layer can be formed on the outer peripheral surface of the base material or the outer peripheral surface of the elastic layer. The surface layer has the metal oxide fine particles (A) and the refractive index nD of 1.6 to 1. And an active energy ray-curable composition containing a (meth) acrylate monomer (B) in the range of 8 and a polyfunctional (meth) acrylate (C) other than the (meth) acrylate monomer (B). It is preferably obtained by irradiating the coating film of the surface layer forming coating solution with an active energy ray and curing. The durability of the intermediate transfer belt can be improved.

  In the intermediate transfer belt of the present invention, the (meth) acrylate monomer (B) having a refractive index nD in the range of 1.6 to 1.8 is a compound represented by the following formulas (a) to (g). It is preferable that it is at least 1 or more types chosen from.

  The metal oxide fine particles (A) in the surface layer, the structural unit derived from the (meth) acrylate monomer (B) having a refractive index nD in the range of 1.6 to 1.8, and the (meth) acrylate monomer (B) In the total of structural units derived from polyfunctional (meth) acrylate (C) other than the above, the content ratio of metal oxide fine particles (A) is 5 to 30% by mass, and the structural unit derived from (meth) acrylate monomer (B) It is preferable that the content rate of 20-50 mass% and the content rate of the structural unit derived from polyfunctional (meth) acrylate (C) are 40-75 mass%.

  The metal oxide fine particles (A) are preferably composed of metal oxide fine particles that have been surface-treated.

<Method for manufacturing intermediate transfer belt>
Next, a manufacturing method in the case of manufacturing a seamless belt using the base material as an intermediate transfer belt by using a coating liquid containing the polyimide precursor or polyamideimide and a carbon black dispersion will be described.

  That is, in the present invention, using a coating liquid containing a carbon black dispersion, a polyimide precursor or polyamideimide, for example, N-methylpyrrolidone as a solvent, and various additives as necessary, a seamless belt is formed. When manufacturing, it can be achieved by including the following steps. That is, the step of preparing a coating solution, the step of applying and casting the coating solution to a support (molding mold), and the solvent in the coating film applied and cast on the support are removed by heating. It is manufactured by a process, a process of heating and heating to promote imidation of the precursor contained in the coating film (also referred to as a baking process), and a process of releasing the formed thin film from the support to obtain a seamless belt. be able to.

  In addition, as a coating liquid of this invention, it can also be used as a solution containing both the said polyimide precursor and a polyamideimide as needed.

  First, a case where centrifugal molding is used as a support (molding mold) will be described as an example. The following description is an example and the conditions are not limited thereto.

  The step of preparing a coating liquid includes preparing a carbon black dispersion in which the acidic carbon black is dispersed in advance with a dispersant having the carboxy group and the amino group, and then the carbon black dispersion and the polyimide precursor or A step of mixing with polyamideimide is preferable.

  Centrifugal molding, which is preferably used in the step of applying and casting the coating liquid on a support (molding mold), is composed of a cylindrical rotating body, and this cylindrical rotating body is slowly While rotating, the coating liquid is applied and cast (forms a coating) so as to be uniform over the entire inner surface of the cylinder. 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 the step of removing the solvent in the coating film applied and cast on the support by heating, it is preferable to efficiently circulate and remove atmospheric vapor (such as a volatile solvent). When a self-supporting film is obtained, it is returned to room temperature and transferred to a heating furnace (firing furnace) capable of high-temperature processing.

  Then, in the process of heating and heating to promote imidation of the precursor contained in the coating film, high temperature heat treatment (firing) of about 300 to 400 ° C. is performed to sufficiently imidize the polyimide 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.

[Image forming apparatus]
<Image forming apparatus>
Next, an image forming method and an image forming apparatus according to the present invention will be described.

  The image forming apparatus uses an intermediate transfer belt to transfer a toner image formed by a charging unit, an exposing unit, a developing unit using a developer containing a small-diameter toner, and a developing unit on an electrostatic latent image carrier (hereinafter also referred to as a photoreceptor). And a transfer means for transferring to the transfer material.

  Specific examples include a copying machine and a laser printer. In particular, an image forming apparatus capable of continuous printing of 5000 sheets or more is preferable. In such an apparatus, an electric field is likely to be generated between the intermediate transfer belt and the transfer material because a large amount of printing is performed in a short time, but the generation of an electric field is suppressed by the intermediate transfer belt of the present invention and stable. Secondary transfer can be performed.

  An image forming apparatus capable of using the intermediate transfer belt of the present invention includes a photosensitive member that forms an electrostatic latent image according to image information, a developing device that develops the electrostatic latent image formed on the photosensitive member, and a photosensitive member. A primary transfer unit that transfers the upper toner image onto the intermediate transfer belt; and a secondary transfer unit that transfers the toner image on the intermediate transfer belt onto a transfer material such as paper or an OHP sheet. By providing the intermediate transfer belt of the present invention as an intermediate transfer belt, stable toner image formation can be performed without causing peeling discharge during secondary transfer.

  The image forming apparatus that can use the intermediate transfer belt of the present invention includes a monochrome image forming apparatus that forms an image with a single color toner, a color image forming apparatus that sequentially transfers a toner image on a photosensitive member to an intermediate transfer belt, and various colors. Examples thereof include a tandem type color image forming apparatus in which a plurality of photoconductors are arranged in series on an intermediate transfer belt.

  The intermediate transfer belt of the present invention is effective when used for tandem color image formation.

  FIG. 2 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus in which the intermediate transfer belt of the present invention can be used.

  In FIG. 2, 1Y, 1M, 1C and 1K are photoreceptors, 4Y, 4M, 4C and 4K are developing means, 5Y, 5M, 5C and 5K are primary transfer rollers as primary transfer means, and 5A is a secondary transfer. Secondary transfer rollers as means, 6Y, 6M, 6C and 6K are cleaning means, 7 is an endless belt-like intermediate transfer belt unit, 24 is a heat roll type fixing device, and 70 is an intermediate transfer belt.

  This image forming apparatus is called a tandem color image forming apparatus, and includes a plurality of sets of image forming units 10Y, 10M, 10C, and 10K, an endless belt-shaped intermediate transfer belt unit 7 as a transfer unit, and a recording member P. An endless belt-shaped sheet feeding / conveying means 21 and a heat roll type fixing device 24 as a fixing means. A document image reading device SC is disposed on the upper part of the main body A of the image forming apparatus.

  As one of the different color toner images formed on each photoconductor, an image forming unit 10Y that forms a yellow image includes a drum-shaped photoconductor 1Y as a first photoconductor, and a periphery of the photoconductor 1Y. A charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, a primary transfer roller 5Y as a primary transfer unit, and a cleaning unit 6Y. In addition, an image forming unit 10M that forms a magenta image as another different color toner image is disposed around a drum-shaped photoconductor 1M as a first photoconductor, and the photoconductor 1M. A charging unit 2M, an exposure unit 3M, a developing unit 4M, a primary transfer roller 5M as a primary transfer unit, and a cleaning unit 6M. In addition, an image forming unit 10C that forms a cyan image as another different color toner image is disposed around the photoconductor 1C as a drum-type photoconductor 1C as a first photoconductor. The charging unit 2C, the exposure unit 3C, the developing unit 4C, a primary transfer roller 5C as a primary transfer unit, and a cleaning unit 6C are provided. In addition, an image forming unit 10K that forms a black image as one of other different color toner images is disposed around a drum-shaped photoconductor 1K as a first photoconductor, and the photoconductor 1K. It has a charging unit 2K, an exposure unit 3K, a developing unit 4K, a primary transfer roller 5K as a primary transfer unit, and a cleaning unit 6K.

  The endless belt-like intermediate transfer belt unit 7 has an endless belt-like intermediate transfer belt 70 as an intermediate transfer endless belt-like second image carrier wound around a plurality of rollers and rotatably supported.

  Each color image formed by the image forming units 10Y, 10M, 10C, and 10K is sequentially transferred onto the rotating endless belt-shaped intermediate transfer belt 70 by the primary transfer rollers 5Y, 5M, 5C, and 5K to be combined. A colored image is formed. A recording member P such as a sheet as a transfer material accommodated in the sheet feeding cassette 20 is fed by a sheet feeding / conveying means 21 and passes through a plurality of intermediate rollers 22A, 22B, 22C, 22D and a registration roller 23 to obtain a secondary. A color image is transferred onto the recording member P at a time by being conveyed to a secondary transfer roller 5A as a transfer means. The recording member P to which the color image has been transferred is fixed by a heat roll type fixing device 24, is sandwiched between paper discharge rollers 25, and is placed on a paper discharge tray 26 outside the apparatus.

  On the other hand, after the color image is transferred to the recording member P by the secondary transfer roller 5A, the residual toner is removed by the cleaning means 6A from the endless belt-shaped intermediate transfer belt 70 from which the recording member P is separated in curvature.

  During the image forming process, the primary transfer roller 5K is always in pressure contact with the photoreceptor 1K. The other primary transfer rollers 5Y, 5M, and 5C are in pressure contact with the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only during color image formation.

  The secondary transfer roller 5A is in pressure contact with the endless belt-shaped intermediate transfer belt 70 only when the recording member P passes through the secondary transfer roller 5A and secondary transfer is performed.

  Further, the housing 8 can be pulled out from the apparatus main body A through the support rails 82L and 82R.

  The housing 8 includes image forming units 10Y, 10M, 10C, and 10K, and an endless belt-shaped intermediate transfer belt unit 7.

  The image forming units 10Y, 10M, 10C, and 10K are arranged in tandem in the vertical direction. An endless belt-shaped intermediate transfer belt unit 7 is disposed on the left side of the photoreceptors 1Y, 1M, 1C, and 1K in the figure. The endless belt-shaped intermediate transfer belt unit 7 includes an endless belt-shaped intermediate transfer belt 70 that can be rotated by winding rollers 71, 72, 73, 74, and 76, primary transfer rollers 5Y, 5M, 5C, and 5K, and a cleaning unit. 6A.

  The image forming units 10Y, 10M, 10C, and 10K and the endless belt-shaped intermediate transfer belt unit 7 are integrally pulled out from the main body A by the drawer operation of the housing 8.

  In this manner, toner images are formed on the photoreceptors 1Y, 1M, 1C, and 1K by charging, exposure, and development, and the toner images of the respective colors are superimposed on the endless belt-shaped intermediate transfer belt 70, and are collectively applied to the recording member P. The image is transferred, and fixed by pressing and heating with a heat roll type fixing device 24 and fixed. The photoreceptors 1Y, 1M, 1C, and 1K after transferring the toner image to the recording member P clean the toner remaining on the photoreceptor during transfer with the cleaning device 6A, and then perform the above charging, exposure, and development cycle. The next image formation is performed.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented.

(Synthesis of dispersant)
<Synthesis of Dispersant 1>
In a nitrogen-substituted glove box, 1.0 g (7.0 mmol) of 2- (dimethylamino) ethyl acrylate (DMAEA), 9.0 g (124.9 mmol) of acrylic acid (AA), 2,2′-azobis ( Isobutyronitrile) (AIBN) 100.00 mg (0.61 mmol) and 10.0 g of methanol were reacted at 60 ° C. for 72 hours. After completion of the reaction, drying was performed to obtain 100 g (yield 100%) of poly (acrylic acid 2- (dimethylamino) ethyl-polyacrylic acid random copolymer. It was 11000 when the weight average molecular weight Mw was measured by the above-mentioned method.

<Synthesis of Dispersant 2>
In a nitrogen-substituted glove box, 1.0 g (7.0 mmol) of 2- (dimethylamino) ethyl acrylate (DMAEA), 190.78 μL of ethyl-2-methyl-2-n-butylterranyl-propionate (BTEE) (0 .83 mmol), 2,2′-azobis (isobutyronitrile) (AIBN) 54.74 mg (0.33 mmol) and methanol 1.0 g were reacted at 60 ° C. for 24 hours.

  Next, 9.0 g (124.9 mmol) of acrylic acid (AA) and 9.0 g of methanol were added to 2- (dimethylamino) ethyl acrylate (initiator, used as a macroinitiator) obtained above. The reaction was carried out at 60 ° C. for 72 hours.

  After completion of the reaction, drying was performed to obtain 8.55 g (yield 86%) of poly (acrylic acid 2- (dimethylamino) ethyl-polyacrylic acid diblock polymer. It was 11000 when the weight average molecular weight Mw was measured by the above-mentioned method.

<Synthesis of Dispersant 3>
In the synthesis of Dispersant 1, the reaction time was shortened so that the weight average molecular weight Mw was 8,000.

<Synthesis of Dispersant 4>
In the synthesis of Dispersant 1, 2- (dimethylamino) ethyl acrylate (DMAEA) is replaced with equimolar acrylic acid (AA), and the reaction time is adjusted so that the weight average molecular weight Mw is 11000. A homopolymer was synthesized.

<Synthesis of Dispersant 5>
In the synthesis of Dispersant 1, the acrylic acid (AA) was replaced with an equimolar amount of 2- (dimethylamino) ethyl acrylate (DMAEA), and the reaction time was adjusted so that the weight average molecular weight Mw was 11000. A polymer was synthesized.

<Manufacture of intermediate transfer belt>
<Preparation of carbon dispersion>
A predetermined amount of dispersant 1 is dissolved in N-methylpyrrolidone (NMP) in advance, carbon black (Mitsubishi Chemical Black Mitsubishi MA7 manufactured by Mitsubishi Chemical) is added, and after stirring, carbon black is dispersed with a ball mill. A carbon black dispersion liquid containing 100 parts by mass of carbon black with respect to 10 parts by mass was prepared.

[Production of Intermediate Transfer Belt 1]
<Belt molding>
A predetermined amount of the carbon black dispersion prepared above is added to a polyimide varnish (Ube Industries U-Varnish A), which is a polyimide precursor, and this is stirred and degassed to prepare a coating solution, which is applied to a mold, Firing was carried out at 350 ° C. for 1 hour to obtain an intermediate transfer belt 1 containing 12% by mass of carbon black with respect to the base resin polyimide.

[Manufacture of intermediate transfer belts 2 to 8]
In the production of the intermediate transfer belt 1, the type of the base material and the carbon dispersion containing carbon black and a dispersant are changed as shown in Table I, and the intermediate transfer belts 2 to 2 are prepared in the same manner as in the production of the intermediate transfer belt 1. 8 was produced.

Details of the materials listed in the table are given below.
Polyimide: U-Varnish A (Polyimide Varnish Ube Industries, Ltd.)
Polyamideimide: HR16NN (polyamideimide varnish, manufactured by Toyobo Co., Ltd.)
Mitsubishi MA7: Mitsubishi Carbon Black MA7 (pH 2.5) (manufactured by Mitsubishi Chemical Corporation)
Mitsubishi # 3030B: Mitsubishi Carbon Black # 3030B (pH 6.5) (Mitsubishi Chemical Corporation)
Mitsubishi # 47: Mitsubishi Carbon Black # 47 (pH 7.5) (Mitsubishi Chemical Corporation)
<Evaluation of intermediate transfer belt>
It was mounted as an intermediate transfer belt of an image forming apparatus “KONICA MINOLTA bizhub C11000” (manufactured by Konica Minolta Co., Ltd.), and the following evaluation test was performed using embossed paper (Rezac 302 g paper) as an image support.

(Quality evaluation of black halftone image)
In the image forming apparatus, under an environment of 30 ° C. and 80% RH, an operation of outputting 1000 black halftone images on the entire surface of the embossed paper was carried out. The quality of black halftone images was evaluated according to the evaluation criteria.

(Quality evaluation of black halftone image)
A: No transfer unevenness is observed. ○: There is transfer unevenness but there is no problem in practical use. Δ: An image having transfer unevenness and a problem in practical use occurs in less than 10 out of 1,000 sheets. 10 or more out of 1,000 cases that have uneven transfer and have practical problems

  As can be seen from Table I, when the intermediate transfer belt of the present invention is used, transfer unevenness is excellent even under high temperature and high humidity. It can also be seen that more preferable results are obtained than when a block copolymer dispersant is used.

1Y, 1M, 1C, 1K Photoconductors 4Y, 4M, 4C, 4K Developing means 5Y, 5M, 5C, 5K Primary transfer roller as primary transfer means 5A Secondary transfer roller as secondary transfer means 6Y, 6M, 6C, 6K Cleaning means 7 Endless belt-like intermediate transfer belt unit 70 Intermediate transfer belt 10Y, 10M, 10C, 10K Image forming portion P Recording member 21 Paper feed / conveying means 24 Heat roll type fixing device A Main body A of image forming apparatus
SC document image reading device

Claims (5)

An intermediate transfer belt used in an electrophotographic image forming apparatus,
Polyimide or polyamideimide,
An intermediate transfer belt comprising a dispersant having a carboxy group and an amino group and acidic carbon black.   2. The intermediate transfer belt according to claim 1, wherein the dispersant contains a block copolymer having a block body having a carboxy group and a block body having an amino group.   3. The intermediate transfer belt according to claim 1, wherein a weight average molecular weight Mw of the dispersant is within a range of 10,000 to 20,000. An intermediate transfer belt manufacturing method for manufacturing the intermediate transfer belt according to any one of claims 1 to 3,
After preparing a carbon black dispersion in which the acidic carbon black is dispersed in advance with a dispersant having the carboxy group and the amino group, the carbon black dispersion and the polyimide precursor or polyamideimide are mixed. An intermediate transfer belt manufacturing method characterized by the above.   An image forming apparatus comprising the intermediate transfer belt according to any one of claims 1 to 3.

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