JP2006317861A - Seamless belt and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seamless belt useful as an intermediate transfer body and a transfer material conveying body, and to provide an image forming apparatus using the belt. <P>SOLUTION: The seamless belt comprises a polyamide imide resin having repeating units expressed by a general formula (1) and a general formula (2) and logarithmic viscosity of 0.4 dl/g or more and containing a conductive material. In the formula, X represents -C(=O)-, -SO<SB>2</SB>-, -O-, -S-, -(CH<SB>2</SB>)<SB>n</SB>-, -NHCO-, -C(CH<SB>3</SB>)<SB>2</SB>- or -C(=O)O-; n represents an integer of 1 to 5; and each of R<SP>1</SP>and R<SP>2</SP>represents a substituent selected from a group consisting of hydrogen and alkyl groups. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a seamless belt and an image forming apparatus using the seamless belt. More specifically, the seamless belt has good durability, and provides a seamless belt useful as an intermediate transfer member and a transfer material carrier used in an image forming apparatus for forming an image by an electrophotographic method such as a copying machine, a facsimile machine, or a printer. Is possible.

  An image forming apparatus that forms an image by an electrophotographic method such as a facsimile or a printer has become an indispensable apparatus for performing office work in an office. In the direction of

  The image forming apparatus includes an apparatus for developing an electrostatic image formed on a photosensitive member as an image carrier with toner as charged particles, and an intermediate transfer member. There are two types of developer, a wet type and a dry type. In the case of a wet type, a high concentration / high viscosity developer with a high toner concentration is used. On the other hand, in the case of a dry type, a solid dry developer is used. In these image forming apparatuses, a toner image formed on a photosensitive drum as an image carrier is transferred as an intermediate transfer member, for example, to an intermediate transfer belt once or a plurality of times (primary transfer). The toner image is collectively transferred to a transfer material (secondary transfer). In addition, there is a method in which a seamless belt is used as a transfer member for a transfer material such as paper.

  These intermediate transfer members and transfer material transport members tend to be subjected to greater mechanical and electrical stresses for higher speeds, and higher durability is required. A material using polyamideimide as these materials is disclosed (for example, Patent Document 1). This document discloses a heat-resistant conductive composition using a polyamideimide having an o-tolidine ring, and has characteristics such as excellent durability as compared with a thermoplastic resin such as polycarbonate and polyvinylidene fluoride. However, since the o-tolidine ring is a rigid component, the durability is increased, but the solubility of the polyamideimide is decreased, and the solution viscosity of the polyamideimide resin solution tends to be increased. For this reason, polyamideimide having an o-tolidine ring introduced is not soluble in N, N-dimethylacetamide or N, N-dimethylformamide having a boiling point of about 160 ° C., which is not highly soluble among amide solvents. It is necessary to use N-methyl-2-pyrrolidone having a high boiling point of about 210 ° C. The intermediate transfer member and the transfer material transport member are prepared by applying a resin solution in which a conductive material is dispersed in polyamideimide to a mold and then drying, and the thickness is very thick as 100 μm after drying. . For example, when the solid content of the resin solution is 20%, it is necessary to dry after applying 500 μm by wet. For this reason, when a solvent having a high boiling point is used, it is necessary to increase the drying temperature or to lengthen the drying time, and there is a problem that productivity is lowered. From the above, there is a demand for improvement in seamless belts using polyamideimide and a conductive material, which have high durability and no productivity.

JP 2003-147199 A

An object of the present invention is to provide a seamless belt useful as an intermediate transfer member and a transfer material transport member, and an image forming apparatus using the same.

  The present invention has arrived at the present invention as a result of intensive studies to solve the above problems. That is, the present invention provides the following seamless belt and an image forming apparatus using the same.

A seamless belt having a repeating unit of the following general formula (1) and general formula (2), and a conductive material contained in a polyamideimide resin having a logarithmic viscosity of 0.4 dl / g or more X is —C (═O) —, —SO ₂ —, —O—, —S—, — (CH ₂ ) _n —, —NHCO—, —C (CH ₃ ) ₂ —, —C (═O ) Represents O-, n is an integer of 1 to 5. R ¹ and R ² represent a substituent selected from the group consisting of hydrogen and an alkyl group.

  An image forming apparatus using the seamless belt as an intermediate transfer member and / or a transfer material conveying belt.

  The seamless belt and the image forming apparatus using the same according to the present invention can cope with high image quality and high speed, have high productivity, and can be used as an image forming apparatus that forms an image by an electrophotographic method such as a copying machine, a facsimile, and a printer. It is possible to provide a seamless belt useful as an intermediate transfer member and a transfer material transport member to be used.

The present invention will be described in detail below. The present invention is a seamless belt characterized in that a conductive material is contained in a polyamideimide having repeating units of the following general formulas (1) and (2). As specific examples of the general formula (1), X represents —C (═O) —, —SO ₂ —, —O—, —S—, — (CH ₂ ) _n —, —NHCO—, —C (CH ₃ ) _2- , -C (= O) O-. n is an integer of 1 or more and 5 or less. Specific examples of the general formula (2) include those in which R ¹ and R ² are hydrogen, R ¹ is an alkyl group such as a methyl group, an ethyl group, and a propyl group, R ² is hydrogen, and R ¹ and R ² are methyl. And alkyl groups such as an ethyl group, an ethyl group and a propyl group. As for the molar ratio of General formula (1) and General formula (2), General formula (1) / General formula (2) = 40-90 / 60-10 is preferable, More preferably, it is 50-80 / 50-20. When the general formula (1) is less than 40 or more than 90, durability may be impaired. The logarithmic viscosity is 0.4 dl / g or more, and the upper limit is not particularly limited, but is desirably 2.0 dl / g. Preferably it is 0.5 dl / g or more and 1.5 dl / g. If it is less than 0.4 dl / g, it becomes brittle and the durability of the seamless belt may be insufficient. On the other hand, if it exceeds 2.0 dl / g, the viscosity of the polyamideimide resin solution becomes high, and handling may be difficult when a seamless belt is produced.

  Polyamideimide having a repeating unit of general formula (1) or general formula (2) is produced by an isocyanate method produced from an acid component and an isocyanate component, or an acid chloride method produced from an acid chloride and an amine, an acid component and an amine. Although it is produced by a known method such as a direct method produced from components, the isocyanate method is preferred from the viewpoint of production cost.

  When synthesizing the polyamide-imide of the present invention by the isocyanate method, the trimellitic anhydride contained in the general formula (1) and the general formula (2) is an essential component as an acid component. A part thereof can be replaced with another polybasic acid or its anhydride as long as it is not impaired. For example, tetracarboxylic acids such as pyromellitic acid, biphenyltetracarboxylic acid, biphenylsulfonetetracarboxylic acid, benzophenonetetracarboxylic acid, biphenylethertetracarboxylic acid, ethylene glycol bistrimellitate, propylene glycol bistrimellitate and their anhydrides, Aliphatic dicarboxylic acids such as oxalic acid, adipic acid, malonic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, dicarboxypolybutadiene, dicarboxypoly (acrylonitrile-butadiene), dicarboxypoly (styrene-butadiene), 1,4 -Cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 4,4'-dicyclohexylmethanedicarboxylic acid, alicyclic dicarboxylic acids such as dimer acid, terephthalic acid, Le acid, diphenyl sulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, aromatic dicarboxylic acids such as naphthalene dicarboxylic acid, trimesic acid, trifunctional carboxylic acids such as cyclohexane tricarboxylic acid. Among these, trimellitic anhydride, pyromellitic acid, benzophenone tetracarboxylic anhydride, and ethylene glycol bistrimethate are preferable.

  In addition, a urethane group can be introduced into the molecule by replacing part of the trimellitic acid compound with glycol. Examples of glycols include alkylene glycols such as ethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, and hexanediol, polyalkylene glycols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol, reactive silicones having functional groups, and the above dicarboxylic acids Examples thereof include polyesters having terminal hydroxyl groups synthesized from one or more acids and one or more glycols.

  When synthesizing the polyamideimide of the present invention by the isocyanate method, the diisocyanate corresponding to the general formula (1) and the general formula (2) is an essential component, but a part of it is within a range that does not impair the characteristics when the seamless belt is formed. Can be replaced with other diisocyanate components. For example, aromatic diisocyanates such as phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyl ether diisocyanate, 4,4′-diphenylsulfone diisocyanate, xylylene diisocyanate, tolylene diisocyanate, tolidine diisocyanate, ethylene diisocyanate, propylene diisocyanate , Aliphatic diisocyanates such as hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, isophorone diisocyanate, 4,4′-dicyclohexylmethane diisocyanate and the like, and among these, reaction Phenylene diisocyanate, 4,4'-diphenyl from the standpoint of durability and durability Tan diisocyanate, 4,4'-diphenyl ether diisocyanate, xylylene diisocyanate, tolylene diisocyanate, aromatic diisocyanates such as tolidine diisocyanate Preferably, still more preferably phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate.

  When the polyamideimide is produced by the acid chloride method, it can be produced by changing the carboxylic acid of the acid component to a carboxylic acid chloride and the isocyanate component to a corresponding amine. Moreover, when manufacturing by a direct method, it can manufacture by changing the said acid component and isocyanate component into a corresponding amine.

  The polyamide-imide resin used in the present invention can be produced by stirring while heating at 60 to 200 ° C. in a polar solvent. Examples of polar solvents include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, γ-butyrolactone, dimethyl sulfoxide, sulfolane and the like, considering the productivity of seamless belts. A lower boiling point is preferred. Therefore, among the polar solvents, N, N-dimethylformamide, N, N-dimethylacetamide, and N-methyl-2-pyrrolidone are preferable, and N, N-dimethylformamide and N, N-dimethylacetamide are more preferable.

  In producing polyamideimide, a catalyst may be used as necessary to accelerate the reaction. For example, amines such as triethylamine, diethylenetriamine, triethylenediamine, and 1,8-diazabicyclo [5.4.0] -7-undecene are used. Metal halides such as sodium fluoride, potassium fluoride and cesium fluoride, organic bases such as sodium methoxide and sodium ethoxide, and inorganic bases such as sodium hydroxide and potassium hydroxide. Of these, amines are preferable in consideration of reactivity and hygroscopicity when a seamless belt is formed, and among them, triethylenediamine and 1,8-diazabicyclo [5.4.0] -7-undecene are preferable. The amount of the catalyst is preferably from 0 mol% to 10 mol%, more preferably from 0.5 mol% to 5 mol%, based on the acid component. When the amount is 10 mol% or more, the catalyst may bleed out from the seamless belt and contaminate the surface.

In the case of producing by the isocyanate method, there is no restriction on the raw material charging order, but (1) acid and isocyanate batch charging (2) excess acid and isocyanate are charged, and then isocyanate is added.
(3) After adding an acid and excess isocyanate, an acid is further added.
The method like this is mentioned. In particular, when N, N-dimethylformamide or N, N-dimethylacetamide is used as a polar solvent, isocyanate may react with these polar groups, and the molecular weight of polyamideimide tends not to increase. For this reason, it is preferable to manufacture by the method of (1) or (2), and the method of (2) is especially preferable. The molar ratio of the acid component to the isocyanate component is preferably in the range of 0.99 to 1.20, more preferably 0.995 to 1.01 for the acid component / isocyanate component. If it is less than 0.99 or exceeds 1.02, the molecular weight is difficult to increase, which may hinder the mechanical properties of the seamless belt.

  The polyamideimide used in the present invention desirably has a glass transition temperature of 100 ° C. or higher and 400 ° C. or lower, more preferably 150 ° C. or higher and 350 ° C. or lower. Below 100 ° C., when the seamless belt is incorporated in the image forming apparatus, there is a risk that the belt may stretch or tear due to lack of heat resistance. On the other hand, when the temperature exceeds 400 ° C., there is a risk that solvent will be lost during the process of producing a seamless belt, and physical properties may be impaired.

  The Young's modulus of the seamless belt used in the present invention is 2 GPa or more and 8 GPa or less, and more preferably 3 GPa or more and 6 GPa or less. The elongation is preferably 10% or more, more preferably 20% or more, and most preferably 40% or more. The tear strength is preferably 2 N / mm or more, and more preferably 3 N / mm or more. The repeated bending test (MIT) is preferably 200 times or more, more preferably 300 times or more, and most preferably 500 times or more. If the Young's modulus is less than 2 GPa, the elongation is less than 10%, the tear strength is less than 2 N / mm, and the repeated bending test is less than 200 times, it becomes impossible to withstand mechanical stress, resulting in higher speed of the image forming apparatus. There is a risk that it cannot respond to. On the other hand, when the Young's modulus exceeds 8 GPa, the running property of the intermediate transfer member is deteriorated, so that there is a possibility that it cannot cope with high image quality. The upper limit of the elongation, tear strength, and repeated bending test is not particularly defined, but is generally 200% or less, 5 N / mm or less, and 50000 times or less.

Next, the manufacturing method of a seamless belt is demonstrated. The seamless belt can be used as an intermediate transfer member and a transfer material transport member, and preferably has semiconductivity. For this reason, a conductive material is added to impart conductivity. This semiconductivity is preferably 10 ⁵ to 10 ¹⁴ Ω / □ in terms of surface resistivity. This semiconductivity can be imparted by adding a conductive material. Examples of the conductive material include carbon black, polythiophene, polyaniline, and the like, and carbon black is preferable in terms of performance and cost. Examples of the carbon black include channel black, furnace black, ketjen black, and acetylene black. These can be used alone or in combination with a plurality of types of carbon black. The type of these carbon blacks can be selected as appropriate depending on the intended conductivity, and depending on the application, those that prevent oxidative degradation such as oxidation treatment and grafting treatment and those that have improved dispersibility in solvents. It is preferable to use it. Moreover, it is preferable that the addition amount satisfies the following conditions.
3 ≦ {conductive material / (weight of conductive material + weight of resin)} × 100 ≦ 40
If the conductive material is less than 3%, the conductivity is low and the toner or transfer material cannot be carried, and if it exceeds 40%, the resin becomes brittle and may not be able to withstand mechanical stress. The amount of the conductive material is preferably 10% by weight to 30% by weight, and more preferably 15% by weight to 25% by weight.

  Known dispersion methods can be applied to the conductive material dispersion method, and examples include ball mills, sand mills, basket mills, three roll mills, planetary mixers, bead mills, ultrasonic dispersion methods, and the like. Select appropriately and perform distributed work.

  In order to enhance the dispersibility of the conductive material, a dispersant may be further added. The dispersant is not particularly limited as long as it meets the object of the present invention. Examples of the dispersant include dodecylbenzenesulfonic acid, lecithin, 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-vinyl pipette) Redone), poly (N-vinylcaprolactam), poly (N-vinyloxazoline) and the like, and a single or a plurality of dispersants can be added. In addition, dispersion stabilizers such as a polymer material, a surfactant, and an inorganic salt can be used within the scope of the object of the present invention.

  A method for examining the dispersion state of these conductive materials is not particularly limited, and examples thereof include a method of visually observing with a microscope and a method of measuring surface gloss.

  The seamless belt of the present invention can be produced by a known method such as a coating method, a spray coating method, a dip coating method, or a centrifugal molding method. Illustrating a specific method for producing the seamless belt of the present invention, a method in which a polyamideimide resin solution containing a conductive material is applied to the inside of a cylindrical mold by a centrifugal molding method and then dried, or a conductive property is applied to the outside of the cylindrical mold. The method of apply | coating and drying the polyamide imide resin solution containing material is illustrated. If the mold separation is poor, silicone-based or fluorine-based release agents may be used in order to improve the releasability.

  In order to further improve the releasability of the toner, the seamless belt of the present invention has a tetrafluoroethylene polymer (PTFE), a tetrafluoroethylene-perfluoroalkoxyethylene copolymer on the surface in contact with the toner and the transfer material. You may coat fluorine resin and silicone resin, such as (PFA) and a fluorinated ethylene propylene copolymer (PFEP). A multilayer structure may also be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not restrict | limited by these Examples. The evaluation shown in the examples was measured by the following method.

1. Logarithmic Viscosity 10 parts by weight of ion-exchanged water was prepared for 1 part by weight of the polyamideimide resin solution, and the polyamideimide resin solution was added to water with a diameter of 0.5 mm and precipitated. Thereafter, the precipitated polyamideimide resin was separated and washed with the same amount of ion-exchanged water used earlier. Washing was performed 5 times every 30 minutes. Thereafter, the resin was separated and dried for 12 hours with a hot air dryer (DH42 manufactured by Yamato Kagaku) at 80 ° C. to obtain a solid resin. Using a solution obtained by dissolving 0.5 g of this solid resin in 100 ml of N-methyl-2-pyrrolidone, measurement was performed at 25 ° C. with an Ubbelohde viscosity tube.

2. Glass transition temperature Polyamideimide resin solution was cast on a polyester film (E5001 manufactured by Toyobo Co., Ltd.) and dried in a hot air dryer (DH42 manufactured by Yamato Kagaku) at 100 ° C for 20 and a half minutes to obtain a semi-dried film. The semi-dried film was peeled off from the base material, attached to a 300 mm × 200 mm metal frame, and dried at 250 ° C. for 1 hour using the same hot air dryer to obtain a 50 μm polyimide resin film. From this film, a film of width 4 mm × length 21 mm was sampled and 3 mm each was sandwiched between chucks, and a dynamic viscoelasticity measuring device (DVA-220 manufactured by IT meter side control) was used with a measurement length of 15 mm, a frequency of 110 Hz, The inflection point of the storage elastic modulus (E ′) when measured at a temperature increase rate of 4 ° C./min was defined as the glass transition temperature.

3. Mechanical properties Samples with a sample size of 10 mm x 80 mm were cut out from the samples containing conductive materials prepared in Examples and Comparative Examples, and fixed by sandwiching them up and down by 20 mm each on the sample fixing chuck of a tensile tester (Orientec RTM-100). Then, measurement was performed under the conditions of a distance between chucks of 40 mm, a pulling speed of 20 mm / min, and a temperature of 25 ° C. and 60 RH%, and the elastic modulus and elongation were measured five times and averaged from the SS curve.

4). Tear Strength A sample having a shape conforming to JIS-K7128 was cut out from the sample containing the conductive material prepared in Examples and Comparative Examples. The sample was sandwiched and fixed 20 mm above and below a sample fixing chuck of a tensile tester (Orientec RTM-100) and measured under the conditions of a pulling speed of 200 mm / min and a temperature of 25 ° C. and 60 RH%.
5. Repeated bending test (MIT)
Samples having a sample size of 10 mm × 100 mm were cut out from the samples containing conductive materials prepared in Examples and Comparative Examples, and averaged by measuring 5 times with a MIT tester (manufactured by Tester Sangyo) at a load of 1 kg and a radius of 0.38 mm.

Synthesis example A
In a reaction vessel equipped with a nitrogen introduction tube and a cooling device, 1 mol of trimellitic anhydride (Mitsubishi Gas Chemical), 0.8 mol of 4,4′-diphenylmethane diisocyanate (Millionate MT manufactured by Nippon Polyurethane Industry), 2,4-trimethyl 0.2 mol of diisocyanate (Coronate T100 manufactured by Nippon Polyurethane Industry Co., Ltd.), 0.02 mol of 1,8-diazabicyclo [5.4.0] -7-undecene (manufactured by Nacalai Tesque) as a catalyst, N, N-dimethyl as a solvent Acetamide (Mitsubishi Gas Chemical Co., Ltd.) was added and reacted at a solid content concentration of 30% at 100 ° C. for 2 hours and then at 120 ° C. for 3 hours. In order to adjust the molecular weight, 0.04 mol of 4,4′-diphenylmethane diisocyanate is added and further reacted, and then cooled and diluted with N, N-dimethylacetamide so that the solid content concentration becomes 25%, and polyamideimide resin is obtained. A solution was obtained. The molar ratio of general formula (1) and general formula (2) was 81/19. The evaluation results are shown in Table 1.

Synthesis example B
In a reaction vessel equipped with a nitrogen introduction tube and a cooling device, 1 mol of trimellitic anhydride (Mitsubishi Gas Chemical), 0.5 mol of 4,4′-diphenylmethane diisocyanate (Millionate MT manufactured by Nippon Polyurethane Industry), 2,4-trimethyl 0.5 mol of diisocyanate (Coronate T100 manufactured by Nippon Polyurethane Industry Co., Ltd.), 0.01 mol of potassium fluoride (GR manufactured by Nacalai Tesque) as a catalyst, and N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical) as a solvent were charged, and the solid content concentration was 30%. The mixture was reacted at 100 ° C. for 2 hours and then at 120 ° C. for 3 hours. In order to adjust the molecular weight, 0.04 mol of 4,4′-diphenylmethane diisocyanate is added and further reacted, and then cooled and diluted with N, N-dimethylacetamide so that the solid content concentration becomes 25%, and polyamideimide resin is obtained. A solution was obtained. The molar ratio of general formula (1) and general formula (2) was 52/48. The evaluation results are shown in Table 1.

Synthesis example C
In a reaction vessel equipped with a nitrogen introduction tube and a cooling device, 0.8 mol of trimellitic anhydride (manufactured by Mitsubishi Gas Chemical), 0.2 mol of pyromellitic anhydride (manufactured by Daicel Chemical Industries), 4,4′-diphenylmethane diisocyanate ( Nippon Polyurethane Industry Millionate MT) 0.7 mol, 2,4-Tolylene Diisocyanate (Nippon Polyurethane Industry Coronate T100) 0.3 mol, 1,8-diazabicyclo [5.4.0] -7-undecene as catalyst 0.02 mol (manufactured by Nacalai Tesque) and N, N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical) as a solvent were charged and reacted at 100 ° C. for 2 hours at a solid content concentration of 30%, and then reacted at 120 ° C. for 3 hours. To adjust the molecular weight, 0.03 mol of 2,4-tolylene diisocyanate was added and further reacted, then cooled and diluted with N, N-dimethylacetamide so that the solid content concentration was 25%, and polyamideimide resin A solution was obtained. The ratio of general formula (1) to general formula (2) was 68/32. The evaluation results are shown in Table 1.

Synthesis example D
In a reaction vessel equipped with a nitrogen introduction tube and a cooling device, 1 mol of trimellitic anhydride, 0.8 mol of o-tolidine diisocyanate (TODI manufactured by Nippon Soda), 2,4-tolylene diisocyanate (Coronate T100 manufactured by Nippon Polyurethane Industry) 0 .2 mol, 1,8-diazabicyclo [5.4.0] -7-undecene (manufactured by Nacalai Tesque) 0.02 mol as a catalyst, N, N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical) as a solvent, and solid content The reaction was carried out at a concentration of 20% at 100 ° C. for 2 hours, and then at 150 ° C. for 3 hours. The solution smelted during the reaction and eventually became cloudy. Cooled and diluted with N, N-dimethylacetamide to a solids concentration of 14%, but because it contains an o-tolidine ring, it has low solubility and does not dissolve in N, N-dimethylacetamide, making it possible to create a seamless belt. There wasn't.

Synthesis example E
1 mol of trimellitic anhydride (Mitsubishi Gas Chemical Co., Ltd.), 1 mol of 4,4'-diphenylmethane diisocyanate (Millionate MT, Nippon Polyurethane Industry Co., Ltd.), potassium fluoride (Nacalai) as catalyst GR of Tesque) 0.01 mol, N, N-dimethylacetamide (manufactured by Mitsubishi Gas Chemical Co., Ltd.) as a solvent was charged and reacted at 100 ° C. for 2 hours at a solid content concentration of 30%, and then reacted at 120 ° C. for 3 hours. In order to adjust the molecular weight, 0.01 mol of Millionate MT was added and further reacted, and then cooled and diluted with N, N-dimethylacetamide to obtain a solid content concentration of 25% to obtain a polyamideimide resin solution. The ratio of general formula (1) and general formula (2) was 100/0. The evaluation results are shown in Table 1.

Synthesis example F
In a reaction vessel equipped with a nitrogen introduction tube and a cooling device, 1 mol of trimellitic anhydride (Mitsubishi Gas Chemical), 0.75 mol of 4,4′-diphenylmethane diisocyanate (Millionate MT manufactured by Nippon Polyurethane Industry), 2,4-tri 0.15 mol of diisocyanate (Coronate T100 manufactured by Nippon Polyurethane Industry), 0.02 mol of 1,8-diazabicyclo [5.4.0] -7-undecene (manufactured by Nacalai Tesque) as a catalyst, N, N-dimethyl as a solvent Acetamide (Mitsubishi Gas Chemical Co., Ltd.) was added and reacted at a solid content concentration of 30% at 100 ° C. for 2 hours and then at 120 ° C. for 3 hours. The solution was cooled and diluted with N, N-dimethylacetamide so that the solid content concentration was 25% to obtain a polyamideimide resin solution. The ratio of general formula (1) to general formula (2) was 83/17. The evaluation results are shown in Table 1.

Examples and Comparative Examples Carbon black (Conductex SC Ultra; Columbyan Carbon Japan) is added to the above synthesis examples A to C, E, and F in an amount of 400 parts by weight with respect to 100 parts by weight of resin solids, and sufficient for 1 hour (25 ° C.) with a ball mill. A carbon black masterbatch was obtained by mixing. The same resin as that used for dispersion was added thereto to adjust the surface resistance to 10 ¹⁰ Ω / □ (the amount of carbon black was 16 to 20% of the total weight). This carbon black-containing varnish was made into a seamless belt by the following procedure. A coating machine having a cylindrical cylinder whose inner peripheral surface was mirror-finished and a slit-shaped outlet having a length corresponding to the width of the cylindrical cylinder was prepared. While rotating the cylinder slowly, carbon black-containing varnish was supplied to the inner peripheral surface. After the supply of the varnish was completed, the rotation speed of the cylinder was increased to make the whole uniform, and then dried at 100 ° C. to 120 ° C. for 30 minutes. Heating was stopped, cooling to room temperature and rotation stopped. At this stage, the organic solvent was evaporated and removed by about 60 to 80% by weight to obtain a self-supporting seamless belt containing the remaining 20 to 40% by weight. The seamless belt is peeled off from the cylinder, and then a rod having an outer diameter that is about 3% smaller than the inner diameter of the belt-like material is inserted into the belt-like material. While heating, a seamless belt containing a conductive agent was obtained by heating at 180 to 200 ° C. for 40 minutes and at 240 to 260 ° C. for 60 to 120 minutes. The total thickness was about 100 microns. The evaluation results are shown in Table 2.

  The seamless belt and the image forming apparatus using the same according to the present invention can cope with high image quality and high speed, have high productivity, and can be used as an image forming apparatus that forms an image by an electrophotographic method such as a copying machine, a facsimile, and a printer. It is possible to provide a seamless belt useful as an intermediate transfer member and a transfer material transport member to be used.

Claims (3)

A seamless belt having a repeating unit of the following general formula (1) and general formula (2), and a conductive material contained in a polyamideimide resin having a logarithmic viscosity of 0.4 dl / g or more X is —C (═O) —, —SO ₂ —, —O—, —S—, — (CH ₂ ) _n —, —NHCO—, —C (CH ₃ ) ₂ —, —C (═O ) Represents O-, n is an integer of 1 to 5. R ¹ and R ² represent a substituent selected from the group consisting of hydrogen and an alkyl group.

  2. The seamless belt according to claim 1, wherein the ratio of the repeating units of the polyamideimide resin is general formula (1) / general formula (2) = 40 to 90 mol% / 60 to 10 mol%.   An image forming apparatus using the seamless belt according to claim 1 as an intermediate transfer member and / or a transfer material conveying belt.