JP5044944B2 - Semiconductive polyamideimide belt, method of manufacturing semiconductive polyamideimide belt, and image forming apparatus - Google Patents

Description

  The present invention relates to a semiconductive polyamide-imide belt and the like, and more particularly to a semi-conductive polyamide-imide belt used in an image forming apparatus.

  An image forming apparatus using an electrophotographic method forms a uniform charge on an image carrier, which is a photoconductive photosensitive member made of an inorganic or organic material, and uses an electrostatic image with a laser beam or the like that modulates an image signal. Then, the electrostatic latent image is developed with a charged toner to obtain a visualized toner image. Then, the toner image is electrostatically transferred to a transfer material such as a recording sheet through an intermediate transfer member, thereby obtaining a required reproduced image. In particular, there is known an image forming apparatus that employs a system in which a toner image formed on the image carrier is primarily transferred to an intermediate transfer member, and a toner image on the intermediate transfer member is secondarily transferred to a recording sheet (for example, , See Patent Document 1).

  Here, in the image forming apparatus employing the above-described intermediate transfer body method, in order to obtain a high-quality transfer image, the electrical resistance value of the intermediate transfer body is controlled within a predetermined range, and in-plane variation ( The difference between the maximum value and the minimum value of the in-plane resistance value is required to be small (see Patent Document 2). This is because if the in-plane variation of the electric resistance value is large, it may cause insufficient charging of the photosensitive member or occurrence of spotted defects. In addition, a certain degree of mechanical strength is also required to withstand a long-term durability test.

  Under such circumstances, an intermediate transfer belt in which a conductive filler (carbon black or the like) is dispersed in a polyimide resin excellent in mechanical properties and heat resistance has been proposed (see, for example, Patent Documents 3 and 4). ). An intermediate transfer belt in which a conductive filler is dispersed in a polyamideimide resin has also been proposed (see, for example, Patent Documents 5 and 6).

JP-A-62-206567 JP 2002-148951 A JP-A-5-77252 Japanese Patent Laid-Open No. 10-63115 Japanese Patent Laid-Open No. 10-226028 JP 2003-261768 A

  Here, an intermediate transfer belt using a polyimide resin is excellent in mechanical properties (strength, etc.) and has a stable resistance value, so that high image quality can be obtained over a long period of time. Since it is insoluble in a solvent, it is difficult to process it into a film. When obtaining a polyimide resin film, a method is usually adopted in which it is dissolved in a solvent in the state of a precursor and polyamic acid, applied onto a substrate, and heated to imidize. Therefore, the productivity is remarkably inferior, and there is still room for improvement from the viewpoint of production cost.

  On the other hand, polyamideimide resin is soluble in solvent, so it has excellent processability and excellent mechanical properties, but polyamideimide resin solution generally has high viscosity and disperses carbon black well. In addition, the storage stability of the polyamide-imide resin solution containing carbon black (particularly, the change in dispersibility with time after mixing and dispersion) is problematic.

  Poor storage stability means that it cannot be left for a long time after preparation and must be used for molding as soon as possible. In particular, when it is intended to obtain a polyamideimide molded body by a dip coating method or a ring float method suitable for mass production, a problem arises because stable dispersibility is required over a long period of time. Although it has also been proposed to add a fluorosurfactant to a polyamideimide solution containing conductive carbon (see, for example, Patent Document 6), the surfactant is easy to move in the film, and particularly has a resistance value on the surface. As a material for an intermediate transfer member that requires a stable resistance value because it is easily affected, there is still room for improvement.

  An object of the present invention is to solve the above conventional problems and achieve the following object. That is, the present invention provides a semiconductive polyamideimide belt having a stable surface resistance value and hardly causing uneven density and spotted defects, a method for producing the semiconductive polyamideimide belt, and the semiconductive polyamideimide belt. An object of the present invention is to provide an image forming apparatus including the above.

  For this purpose, the semiconductive polyamideimide belt of the present invention is characterized in that it contains a polyamideimide resin, a polymer dispersant, and conductive fine particles.

  Further, the present invention is regarded as an image forming apparatus, and the image forming apparatus according to the present invention includes an image carrier, a charging unit that charges the surface of the image carrier, and a latent image formation that forms a latent image on the surface of the image carrier. Developing means for developing the latent image with toner to form a toner image; first transfer means for primary transfer of the toner image to the intermediate transfer belt; and a toner image transferred to the intermediate transfer belt on the transfer object A second transfer means for secondary transfer; and a fixing means for fixing the toner image to the transfer target. The intermediate transfer belt is a semiconductive material containing a polyamideimide resin, a polymer dispersant, and conductive fine particles. It is characterized by being a conductive polyamideimide belt.

  Further, the present invention is regarded as a method for producing a semiconductive polyamide-imide belt, and the method for producing a semi-conductive polyamide-imide belt according to the present invention is obtained by dispersing conductive fine particles in a solution in which a polymer dispersant is dissolved. Further, the polyamide-imide resin is further dissolved to form a coating liquid, and the coating liquid is heated and dried, or the conductive fine particles are dispersed in the solution in which the polymer dispersant is dissolved, The monomer as a precursor is dissolved, the monomer is further polymerized to form a coating solution, and the coating solution is heat-dried.

  According to the present invention, the dispersibility of the conductive fine particles is improved.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram illustrating a color image forming apparatus 100 to which the exemplary embodiment is applied. A color image forming apparatus 100 shown in FIG. 1 includes four toner cartridges 1, a pair of fixing rolls 2, a backup roll 3, a tension roll 4, a secondary transfer roll (secondary transfer means) 5, a paper path 6, and a paper tray. 7, laser generator 8, four photoconductors (image carrier) 9, four primary transfer rolls (primary transfer means) 10, drive roll 11, transfer cleaner 12, four charging rolls 13, photoconductor cleaner 14 The developing unit 15 and the intermediate transfer belt 16 are included as main components. In the color image forming apparatus 100 shown in FIG. 1, the semiconductive polyamideimide belt in the present embodiment is used as an intermediate transfer belt 16 that functions as a toner image superimposing unit and a toner image transferring unit.

  Next, the configuration of the color image forming apparatus 100 shown in FIG. 1 will be described sequentially. First, around the photoconductor 9, a primary transfer roll 10 and a photoconductor cleaner 14 are arranged counterclockwise via a charging roll 13, a developing device 15, and an intermediate transfer belt 16, and one set of these is set. The member forms a developing unit corresponding to one color. Each developing unit is provided with a toner cartridge 1 for replenishing the developer in the developing unit 15, and the photosensitive member 9 of each developing unit is exposed to a photosensitive member between the charging roll 13 and the developing unit 15. A laser generator 8 that can irradiate the surface of the body 9 with laser light corresponding to image information is provided.

  Four developing units corresponding to four colors (for example, cyan, magenta, yellow, and black) are arranged in series in the horizontal direction in the image forming apparatus 100, and the photosensitive members 9 and 1 of the four developing units are arranged. An intermediate transfer belt 16 is provided so as to pass through the nip portion with the next transfer roll 10. The intermediate transfer belt 16 is stretched by a backup roll 3, a tension roll 4, and a drive roll 11 provided on the inner peripheral side thereof in the following order in the counterclockwise direction. The four primary transfer rolls 10 are positioned between the tension roll 4 and the drive roll 11. A transfer cleaner 12 for cleaning the outer peripheral surface of the intermediate transfer belt 16 is provided on the opposite side of the drive roll 11 via the intermediate transfer belt 16 so as to be in pressure contact with the drive roll 11.

  A toner image formed on the outer peripheral surface of the intermediate transfer belt 16 on the surface of the recording paper conveyed from the paper tray 7 via the paper path 6 to the opposite side of the backup roll 3 via the intermediate transfer belt 16. A secondary transfer roll 5 for transferring the ink is provided so as to be in pressure contact with the backup roll 3. On the outer peripheral surface of the intermediate transfer belt 16 between the backup roll 3 and the drive roll 11, a neutralizing roll (not shown) is provided for neutralizing the outer peripheral surface.

  Further, a paper tray 7 for stocking recording paper is provided at the bottom of the color image forming apparatus 100, and a backup roll 3 and a secondary transfer roll 5 that constitute a secondary transfer unit from the paper tray 7 via a paper path 6. It can supply so that it may pass through the press-contact part. The recording paper that has passed through the press contact portion can be further transported by a transport means (not shown) so as to be inserted through the press contact portions of the pair of fixing rolls 2, and finally discharged outside the color image forming apparatus 100. it can.

  Next, an image forming method using the color image forming apparatus 100 of FIG. 1 will be described. The toner image is formed for each developing unit. After uniformly charging the surface of the photoconductor 9 rotating counterclockwise by the charging roll 13, the photoconductor 9 charged by the laser generator 8 (exposure device) is used. A latent image is formed on the surface, and then the latent image is developed with a developer supplied from the developing device 15 to form a toner image, which is conveyed to a pressure contact portion between the primary transfer roll 10 and the photoreceptor 9. The transferred toner image is transferred to the outer peripheral surface of the intermediate transfer belt 16 that rotates in the arrow X direction. The photosensitive member 9 after the transfer of the toner image is cleaned with toner or dust adhered to the surface by the photosensitive member cleaner 14 to prepare for the formation of the next toner image.

  The toner images developed for each color developing unit are sequentially superimposed on the outer peripheral surface of the intermediate transfer belt 16 so as to correspond to the image information, and are conveyed to the secondary transfer unit by the secondary transfer roll 5. The image is transferred from the paper tray 7 to the surface of the recording paper conveyed via the paper path 6. The recording paper on which the toner image has been transferred is further fixed by being heated by pressure when passing through the pressure contact portion of the pair of fixing rolls 2 constituting the fixing portion, and an image is formed on the surface of the recording medium. Then, it is discharged out of the color image forming apparatus 100.

  The intermediate transfer belt 16 that has passed through the secondary transfer portion further advances in the direction of arrow X, and after the outer peripheral surface is neutralized by a neutralizing roll (not shown), the outer peripheral surface is further cleaned by the transfer cleaner 12, and then the next toner image is obtained. Preparing for the transfer of

  As the photosensitive member 9 (image carrier), a conventionally known one can be used, and as the photosensitive layer, a known one such as organic or amorphous silicon can be used. Are preferred. When the image carrier is cylindrical, it can be obtained by a known manufacturing method such as surface processing after extrusion molding of aluminum or an aluminum alloy. It is also possible to use the belt-shaped image carrier.

  The charging roll 13 (charging means) is not particularly limited. For example, a contact-type charger using a conductive or semiconductive roller, brush, film, rubber blade, a scorotron charger using corona discharge, Known chargers such as a corotron charger can be used. Among these, a contact-type charger is preferable in terms of excellent charge compensation capability. The charging means normally applies a direct current to the electrophotographic photosensitive member, but an alternating current may be applied in a superimposed manner.

  The laser generator 8 (exposure means) is not particularly limited. For example, a light source such as a semiconductor laser light, an LED light, or a liquid crystal shutter light, or a desired light source from these light sources through a polygon mirror is provided on the surface of the photoreceptor 9. And optical system equipment that can be exposed like the above image.

  The developing device 15 (developing means) can be appropriately selected according to the purpose. For example, the developing device 15 is developed by bringing a one-component developer or a two-component developer into contact or non-contact with each other using a brush, a roller, or the like. A well-known developing device etc. are mentioned.

  Examples of the primary transfer roll 10 (first transfer unit) include a contact transfer charger using a belt, a roller, a film, a rubber blade, and the like, a scorotron transfer charger using a corona discharge, a corotron transfer charger, and the like. A transfer charger known per se can be used. Among these, a contact type transfer charger is preferable in that it has excellent transfer charge compensation capability. In the present invention, in addition to the transfer charger, a peeling charger can be used in combination.

  Examples of the secondary transfer roll 5 (second transfer unit) include a contact transfer charger, a scorotron transfer charger, and a corotron transfer charger. Among these, a contact-type transfer charger is preferable like the first transfer unit. If the contact-type transfer charger such as a transfer roll is pressed strongly, the image transfer state can be maintained in a good state. Also, when a contact type transfer charger such as a transfer roll is pressed at the position of a roller that guides the intermediate transfer belt 16, the toner image is transferred from the intermediate transfer belt 16 to the transfer medium (paper) in a good state. It becomes possible to do in.

The fixing roll 2 (fixing means) is not particularly limited, and examples thereof include known fixing devices such as a heat roller fixing device and an oven fixing device.
The cleaning means is not particularly limited, and a known cleaning device or the like may be used.

  Furthermore, it is also preferable to install a light neutralizing means. Examples of the light neutralizing means include tungsten lamps and LEDs. Examples of the light quality used in the light neutralizing process include white light such as tungsten lamps and red light such as LED light. The irradiation light intensity in the photostatic process is usually set to output several times to about 30 times the amount of light indicating the half exposure sensitivity of the electrophotographic photosensitive member.

  Next, the intermediate transfer belt 16 in the present embodiment will be described. The intermediate transfer belt 16 in the present embodiment includes a polyamideimide resin (hereinafter sometimes abbreviated as “PAI resin”), a polymer dispersant, and conductive fine particles.

  In the present embodiment, as a raw material for the PAI resin, generally, a trivalent carboxylic acid component (tricarboxylic acid component) having an acid anhydride group and isocyanate or diamine can be used. As the trivalent carboxylic acid component, trimellitic anhydride is preferable in view of flexibility, storage stability, and cost. Further, the trimellitic anhydride and a derivative of a trivalent carboxylic acid having an acid anhydride group that reacts with another isocyanate group or amino group can be used in combination. Preferred structures include the following.

ここで、Ｒは水素、炭素数１〜１０のアルキル基、フェニル基を示し、Ｘは−ＣＨ_２−、−ＣＯ−、−ＳＯ_２−、または−Ｏ−を示す。

Here, R represents hydrogen, an alkyl group having 1 to 10 carbon atoms, or a phenyl group, and X represents —CH ₂ —, —CO—, —SO ₂ —, or —O—.

  In addition to these, if necessary, tetracarboxylic dianhydride (pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4, 4'-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride, 1,4,5,8 -Naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4'-sulfonyldiphthalic dianhydride, m-terphenyl-3,3 ', 4 4'-tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis (2,3- or 3,4 -Dicarboxyphenyl) propane dianhydride, 2,2-bis (2 3- or 3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis [4- (2,3- or 3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 1,1,1 , 3,3,3-hexafluoro-2,2-bis [4- (2,3- or 3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 1,3-bis (3,4-di Carboxyphenyl) -1,1,3,3-tetramethyldisiloxane dianhydride, butanetetracarboxylic dianhydride, bicyclo- [2,2,2] -oct-7-ene-2,3,5 6-tetracarboxylic dianhydride), aliphatic dicarboxylic acid (succinic acid, glutaric acid, adipic acid, azelaic acid, suberic acid, sebacic acid, decanedioic acid, dodecanedioic acid, dimer acid, etc.), aromatic dicarboxylic acid Acid (isophthalic acid, Terephthalic acid, phthalic acid, naphthalenedicarboxylic acid, oxydibenzoic acid, etc.) can be used in combination.

As the isocyanate, 3,3′-dimethylbiphenyl-4,4′-diisocyanate, 2,2′-dimethylbiphenyl-4,4′-diisocyanate, biphenyl-4,4′-diisocyanate, biphenyl-3,3′- Diisocyanate, biphenyl-3,4'-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 can be used. As the diamine, a compound having the same structure as the isocyanate and having an amino group substituted in place of the isocyanato group can be used.
It is preferable to use a plurality of these from the viewpoint of reducing density unevenness during printing.

  As the solvent used when forming the PAI resin using the above raw materials (performing the polymerization reaction), a polar solvent (organic polar solvent) is preferably mentioned from the viewpoint of solubility. Specific examples of the polar solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethyl Examples include phosphortriamide, N-methyl-2-pyrrolidone, pyridine, tetramethylene sulfone, dimethyltetramethylene sulfone, and γ-butyrolactone, and N, N-dimethylacetamide and N-methyl-2-pyrrolidone are preferable. These can be used singly or in combination.

  As a blending ratio of the isocyanate or diamine and the tricarboxylic acid component, the total ratio of isocyanate groups or amino groups to the total number of carboxyl groups and acid anhydride groups of the acid component is usually 0.6 to 1.4, preferably Is 0.7 to 1.3, more preferably 0.8 to 1.2. If it is less than 0.6 or exceeds 1.4, it tends to be difficult to increase the molecular weight of the resin.

Examples of the method for forming the PAI resin include the following production methods.
(1) A method in which when an isocyanate is used, a PAI resin is obtained by reacting an isocyanate component and a tricarboxylic acid component at a time.
(2) A method in which an excess amount of an isocyanate component is reacted with an acid component to synthesize an amide-imide oligomer having an isocyanate group at the end, and then a tricarboxylic acid component is added and reacted to obtain a PAI resin.
(3) After reacting an excess amount of a tricarboxylic acid component with an isocyanate component to synthesize an amideimide oligomer having a carboxylic acid or an acid anhydride group at the terminal, the acid component and the isocyanate component are added and reacted to form a PAI resin. How to get.

  In the case of using an amine, it can be obtained by the same production method as in the case of using the isocyanate shown above, but in addition, by reacting an amine with tribasic acid anhydride monochloride as an acid component at a low temperature for several hours. It can also be obtained.

The number average molecular weight of the PAI resin thus obtained is preferably 10,000 to 45,000. If the number average molecular weight is less than 10,000, the film formability tends to deteriorate and the flex resistance tends to decrease. If it exceeds 45,000, the dispersibility of the conductive fine particles, the formability as a tubular film, the thickness accuracy and the like tend to be inferior.
The number average molecular weight of the PAI resin is sampled at the time of resin synthesis, measured by gel permeation chromatography (GPC) using a standard polyethylene calibration curve, and the synthesis is continued until the target number average molecular weight is reached. Therefore, it is managed within the above range.

  In the present embodiment, the polymer dispersant is preferably a polymer dispersant having a nitrogen atom in the molecular structure from the viewpoint of better dispersing the conductive fine particles in the PAI resin. More specifically, such a polymer dispersant is not particularly limited. For example, poly (N-vinyl-2-pyrrolidone), poly (N, N′-diethylacrylamide), poly (N -Vinylformamide), poly (N-vinylacetamide), poly (N-vinylphthalamide), poly (N-vinylsuccinamide), poly (N-vinylurea), poly (N-vinylpiperidone), poly (N- Vinyl caprolactam), poly (N-vinyloxazolidone) and the like. Among them, poly (N-vinyl-2-pyrrolidone), poly (N, N′-diethylacrylamide), poly (N-vinylacetamide), Poly (N-vinylpiperidone) is preferable because of its excellent dispersibility. In addition, these can be used individually by 1 type or can use 2 or more types together.

  The blending amount of such a polymer dispersant is usually 0.01 to 3.0 parts by weight, preferably 0.05 to 2 parts by weight with respect to 10 parts by weight of the conductive fine particles. If the blending amount of the polymer dispersant is excessively large, the humidity dependence of the resistance value may be increased. On the other hand, if the blending amount is excessively small, the dispersibility of the conductive fine particles may be decreased.

In the present embodiment, the conductive fine particles impart semiconductivity to the PAI resin. The material for such conductive fine particles is not particularly limited, and examples thereof include metals, metal oxides, conductive polymers, carbon black (hereinafter sometimes abbreviated as “CB”) and the like. It is done. These may be used alone or in combination of two or more. When two or more types are used in combination, they may be simply mixed, or may be in the form of a solid solution or fusion.
The average particle size of the conductive fine particles in the present embodiment is usually 0.3 μm or less, preferably 0.1 μm or less. If the average particle size is excessively large, poor dispersion may occur and image defects may occur.

Examples of the metal include aluminum, zinc, copper, chromium, nickel, silver, and stainless steel, or those obtained by depositing these metals on the surface of plastic particles.
Examples of the metal oxide include zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide, indium oxide doped with tin, tin oxide doped with antimony and tantalum, and zirconium oxide doped with antimony. .
Furthermore, examples of the conductive polymer include polyaniline and polythiophene.

  Among them, it is excellent in dispersibility with respect to PAI resin, more stable storage stability (for example, maintaining a stable dispersion state even after standing for 3 days or more), and there is no unevenness in the applied electrical resistance. CB is preferably used.

In the present embodiment, a commercially available product can be used as CB. More specifically, although not particularly limited, for example, furnace black includes “Special Black 550”, “Special Black 350”, “Special Black 250”, “Special Black 100”, and “Printex” manufactured by Degussa Huls. “35”, “Printex 25”, “MA7”, “MA77”, “MA8”, “MA11”, “MA100”, “MA100R”, “MA220”, “MA230”, manufactured by Cabot Corporation, “manufactured by Mitsubishi Chemical Corporation” MONARCH 1300, MONARCH 1100, MONARCH 1000, MONARCH 900, MONARCH 880, MONARCH 800, MONARCH 700, MOGUL L, RE AL 400R ", and" VULCAN XC-72R "and the like.
Also, as the channel black, “Color Black FW200”, “Color Black FW2”, “Color Black FW2V”, “Color Black FW1”, “Color Black FW18”, “Special Black”, “Special Black” manufactured by Degussa Huls, Inc. "Color Black S170", "Color Black S160", "Special Black 5", "Special Black 4", "Special Black 4A", "Printex 150T", "Printex U", "Print 140", "Print 140", "Print 140" Printex 140V "etc. are mentioned. In the present embodiment, a single type or a plurality of types of CBs may be used in combination.

The CB used in the present embodiment is preferably an oxidized CB in that the difference in the common logarithmic value of the surface resistivity in the present embodiment can be further reduced.
Here, the pH value of the oxidized carbon black is preferably pH 5.0 or less, more preferably pH 4.5 or less, and still more preferably pH 4.0 or less. Oxidized carbon having a pH of 5.0 or lower has an oxygen-containing functional group such as a carboxyl group, a hydroxyl group, a quinone group, and a lactone group on the surface, so that it has good dispersibility in the resin 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 the electric field concentration due to the transfer voltage is difficult to occur.

In the present embodiment, when two or more CBs are used, it is preferable that they have substantially different conductivity. As such CB, for example, those having different physical properties such as the degree of oxidation treatment, DBP oil absorption, specific surface area by BET method using nitrogen adsorption, and the like can be used. By containing two or more kinds of conductive powder, there is an effect that mixing and dispersion can be enhanced.
Here, when two or more kinds of conductive powders having different conductivity are added, for example, a conductive powder that expresses high conductivity is preferentially added, and then a conductive powder having a low conductivity is added to obtain surface resistivity. Can be adjusted.

Moreover, CB to be used can be purified. Purification refers to removing impurities mixed in the manufacturing process, such as residual oxidant, impurities such as treating agents and by-products, and other inorganic and organic impurities.
As a method for performing such purification, for example, high-temperature heat treatment in an inert gas or in a vacuum of about 500 ° C. to 1000 ° C., treatment with an organic solvent such as carbon disulfide or toluene, mixing of a water slurry, or an aqueous organic acid solution For example, a method of removing impurities by a mixing process or the like can be employed. Since the heat treatment of the powder is difficult to handle in the production process and has a problem of using a lot of energy, the treatment mainly using an organic solvent or water is preferable as a purification method. In particular, a water-based treatment method is preferable from the viewpoint of safety. In addition, it is preferable to use ion-exchange water, ultrapure water, distilled water, and ultrafiltration water as water to be used to prevent impurities from being mixed.

  In the present embodiment, from the viewpoint of stably providing semiconductivity to the PAI resin, CB grafted with various polymers is also preferably used. In particular, carbon black obtained by grafting a copolymer having a reactive group capable of reacting with a functional group on the surface of the carbon black and having a good affinity with the surface of the carbon black and another segment is preferable. Details of such grafted carbon black are described in JP-A-10-120935. Further, carbon black grafted with a hydrophilic polymer is preferable from the viewpoint of uniformly mixing and dispersing carbon black. Examples of the hydrophilic polymer include poly (N-vinyl-2-pyrrolidone), poly (N, N′-diethylacrylamide), poly (N-vinylformamide), poly (N-vinylacetamide), and poly (N-vinyl). Phthalamide), poly (N-vinylsuccinamide), poly (N-vinylurea), poly (N-vinylpiperidone), poly (N-vinylcaprolactam), poly (N-vinyloxazolidone) and the like. Further, the carbon black may be one (such as a block copolymer) interposing a segment having good affinity with the surface of the carbon black when the hydrophilic polymer is grafted onto the carbon black.

  The blending amount of the CB is usually 10% by mass to 30% by mass, preferably 18% by mass to 30% by mass with respect to the resin solid content. Setting such a blending amount is important for suppressing in-plane variation of the surface resistivity of the semiconductive belt and obtaining stable performance. Among these, by containing 18% by mass to 30% by mass of CB, the effect can be maximized, and in-plane unevenness and electric field dependency of the surface resistivity can be remarkably improved. In addition, when the blending amount of CB is less than 10% by mass, the uniformity of electrical resistance is lowered, and in-plane unevenness of surface resistivity and electric field dependency may be increased. On the other hand, if it exceeds 30% by mass, it may be difficult to obtain a desired resistance value.

As a manufacturing method of the intermediate transfer belt 16, for example, the following method can be employed.
(I) A production method in which conductive fine particles are dispersed in a solution in which a polymer dispersant is dissolved, and then a polyamide-imide resin is further dissolved to form a coating solution, and the coating solution is heated and dried.
(Ii) After dispersing the conductive fine particles in the solution in which the polymer dispersant is dissolved, the monomer that is a precursor of the polyamide-imide resin is dissolved, and the monomer is further polymerized to form a coating solution. A manufacturing method for heat-drying the working fluid.
Among them, the use of the method (ii) is preferable because the solution viscosity at the time of dispersing the conductive fine particles can be suppressed and the dispersion is easy.

In general, CB tends to cause secondary aggregation, and a conduction path is generated by aggregation, which leads to variation in electric resistance value in the belt. When such a belt is used as an intermediate transfer belt of an electrophotographic recording apparatus, problems such as transfer unevenness (density unevenness or speckle defect) occur in a toner image transferred to a printing sheet. As described above, the variation in the electric resistance value affects the intermediate transfer because the non-uniformity of the charge-suppressing ability of the semiconductive belt and the non-uniformity of the ability to suppress the conductive property are likely to cause local peeling discharge and conduction. It is thought to be.
In addition, when the dispersion of CB is not sufficient, it is difficult to form a stable film in a manufacturing method that requires a highly conductive coating solution stability such as dip coating and ring float coating, particularly for a semiconductive polyamideimide belt. There is a case. On the other hand, for spiral coats that use up the coating solution, the polyamideimide coating solution with conductive powder dispersed is generally non-Newtonian, so it is difficult to level and the spiral pattern appears in the image. It was difficult to obtain a high quality image.
In the present embodiment, since the coating liquid shown in the above (i) and (ii) is used, the liquid life of the coating liquid is long, and CB is sufficiently dispersed. A high-quality belt with reduced risk of defects can be obtained.

Here, the solvent used when the intermediate transfer belt 16 is manufactured is not particularly limited, and a solvent similar to the polymerization solvent for the PAI resin can be used.
Moreover, as a dispersion process, 0.01-10 mass parts of polymer dispersing agents with respect to 10 mass parts of CB, Preferably 0.05 mass part-2.0 mass parts are previously used for solvent 10-100. After dissolving in 15 parts by mass, preferably 15 to 70 parts by mass, CB can be added to perform dispersion treatment.

  Although the PAI resin and polymer dispersant can be dissolved in a solvent and CB is added thereto, the dispersion treatment can be performed. However, the PAI resin solution is very viscous, and carbon black is directly added to this solution. In order to disperse, a very large shear stress is required, and it is difficult to improve the dispersibility (CB uniformity) of the dispersion, and it is difficult to obtain a uniform resistor. However, by dispersing CB in a solvent in advance using a polymer dispersant and further synthesizing a polyamideimide resin or adding a polyamideimide resin, it becomes possible to obtain a stable and good dispersibility. .

When performing dispersion processing, ball mill, dyno mill, coball mill, etc. using fine media can also be used. However, since mixing of fine media affects the image quality, a media-free dispersion method that does not use media is preferred, especially high viscosity A jet mill or the like is preferable in that the solution can be uniformly dispersed.
As a preferred example of dispersion, dispersion in a jet mill is preferably performed by a collision pressure of 150 MPa or more. The number of treatments is not particularly limited, but is preferably in the range of 1 to 10 times.

  When polymerizing a polyamideimide resin raw material, the reaction temperature is preferably set to 80 ° C. or less, particularly preferably 5 to 50 ° C., and the reaction time is 5 to 10 hours.

  In addition, the PAI resin solution in which CB is dispersed tends to be a high-viscosity solution, and bubbles mixed during production are difficult to escape. If the intermediate transfer belt 16 is formed with bubbles remaining, defects such as belt protrusions, dents, and holes may occur due to the bubbles generated during application. For this reason, it is desirable to perform a defoaming process on the PAI resin solution in which CB is dispersed. Defoaming is preferably performed immediately before application as much as possible.

When the intermediate transfer belt 16 is manufactured as a seamless belt, for example, a method in which the outer peripheral surface of a cylindrical mold is immersed in a coating solution, a method in which a coating solution is applied to the inner peripheral surface, a method in which centrifugation is performed, The PAI resin solution is developed in a ring shape by an appropriate method such as a method of filling the mold with the coating liquid, the developed layer is dried and formed into a bell-shaped shape, and the molded product is heated and dried. An appropriate method according to the prior art, such as a method of recovering from a mold, can be employed (JP-A 61-95361, JP-A 64-22514, JP-A 3-180309, etc.).
Conventionally, a method in which the outer peripheral surface of a cylindrical mold is immersed in a coating solution has high productivity and excellent film uniformity. However, since the polyamideimide solution is used while circulating, long-term dispersion stability is achieved. Sex is required. On the other hand, in the method of applying to the inner peripheral surface and the method of further centrifuging, since the polyamideimide solution can be used up, the dispersion stability is less likely to cause problems even in a relatively short time. Since thixotropy is high, it is difficult to level, it is difficult to obtain a uniform film, and productivity is low. On the other hand, the composition containing the polyamide-imide resin, polymer dispersant, and conductive fine particles prepared in the present embodiment is excellent in long-term dispersion stability, and thus has high productivity, It is possible to produce by the method of immersing in the outer peripheral surface of the mold with excellent uniformity.
That is, using a polyamideimide coating solution with good dispersibility of the conductive powder, the cylindrical substrate is arranged perpendicular to the ground, and the cylindrical substrate is placed in contact with the coating solution uniformly on the outer periphery. By using a method (ring float method) in which the coating liquid is adhered to the surface of the substrate by relatively moving the coating liquid surface, a spiral pattern is not generated and stable film formation is possible.
In the manufacture of the seamless belt, a mold release process can be performed.

Next, a preferred range of various physical properties of the intermediate transfer belt 16 in the present embodiment and a measuring method thereof will be described.
(Surface resistivity)
In general, a belt-shaped intermediate transfer member with a high degree of design freedom is used, and the photosensitive member and the 1st-BTR (primary transfer roller) are offset and arranged to affect the surface potential of the photosensitive member during primary transfer. However, in a so-called high-speed machine that performs high-speed printing in particular, an electric field is applied for a short time, and the difference in rising of the belt resistance is emphasized, and the density tends to become uneven in image quality. And since the electrical resistance at this time has an offset on an apparatus structure, it has relation with surface resistance instead of volume resistance considered conventionally.
In the intermediate transfer belt 16 in the present embodiment, the rise of the belt surface resistivity is reduced, that is, the difference between the common logarithmic value of the surface resistivity after 10 sec and the common logarithm of the surface resistivity after 30 msec. (Hereinafter, referred to as “common difference in logarithm of surface resistivity”) as an absolute value of 1.0 (LogΩ / □) or less, preferably 0.7 (LogΩ / □) or less, more preferably , 0.05 (LogΩ / □) or less. By setting such a range, density unevenness generated in a high-speed machine can be suppressed and printing speeds other than high-speed printing can be supported, so that an intermediate transfer belt having a wide application range of the apparatus can be obtained.
The common logarithmic value difference of the surface resistivity can be controlled by the above-described CB type and CB dispersion method.

  Further, the common logarithm of the surface resistivity of the intermediate transfer belt 16 after 30 msec of voltage application is usually 9 to 13 (LogΩ / □), preferably 10 to 12 (LogΩ / □). If the common logarithmic value of the surface resistivity after 30 msec of voltage application exceeds 13 (LogΩ / □), the recording medium and the intermediate transfer belt may be electrostatically adsorbed during the secondary transfer, and the recording medium may not be peeled off. is there. On the other hand, if the common logarithm of the surface resistivity after 30 msec of voltage application is less than 9 (Log Ω / □), the holding power of the toner image primarily transferred to the intermediate transfer belt is insufficient, and the graininess of the image quality and the image disturbance May occur. The common logarithmic value of the surface resistivity 30 msec after the voltage application can be controlled by selecting the type of CB and the amount of CB added.

The surface resistivity can be measured in accordance with JIS K6911 (1995) using a circular electrode (for example, “UR probe” of Hiresta IP manufactured by Mitsubishi Yuka Co., Ltd.). A method for measuring the surface resistivity will be described with reference to the drawings. FIG. 2 is a schematic plan view (a) and a schematic cross-sectional view (b) showing an example of a circular electrode.
The circular electrode shown in FIG. 2 includes a first voltage application electrode A and a plate-like insulator B. The first voltage application electrode A has a cylindrical electrode portion C and a cylindrical ring electrode having an inner diameter larger than the outer diameter of the cylindrical electrode portion C and surrounding the cylindrical electrode portion C at a constant interval. Part D is provided. The measurement target T is sandwiched between the cylindrical electrode portion C and the ring electrode portion D and the plate insulator B in the first voltage application electrode A, and the cylindrical electrode portion C and the ring shape in the first voltage application electrode A are sandwiched. A current I (A) flowing when a voltage V (V) is applied between the electrode part D is measured, and a surface resistivity ρs (Ω / □) of the measurement target T is calculated by the following equation (1). be able to. Here, in the following formula (1), d (mm) indicates the outer diameter of the cylindrical electrode portion C, and D (mm) indicates the inner diameter of the ring-shaped electrode portion D. In the present embodiment, the current I (A) is measured 10 seconds after application of the voltage V (V) and 30 milliseconds later.
Formula (1) ρs = π × (D + d) / (D−d) × (V / I)

More specifically, the conditions for measuring the surface resistivity are as follows.
Electrode used: Circular electrode (UR probe of Hiresta IP manufactured by Mitsubishi Oil Chemical Co., Ltd .: outer diameter Φ16 mm of cylindrical electrode C, inner diameter Φ30 mm, outer diameter Φ40 mm of ring-shaped electrode portion D).
Measurement environment: 22 ° C./55% RH.
Voltage: 100V.

(Volume resistivity)
The intermediate transfer belt 16 preferably has a common logarithmic value of volume resistivity of 8 to 13 (Log Ωcm). If the common logarithmic value of the volume resistivity is less than 8 (Log Ωcm), the electrostatic force that holds the charge of the unfixed toner image transferred from the image carrier to the intermediate transfer belt 16 becomes difficult to work. Due to the electrostatic repulsion between the toners and the force of the fringe electric field in the vicinity of the image edge, the toner may be scattered around the image and an image with a large noise may be formed. On the other hand, if the common logarithmic value of the volume resistivity exceeds 13 (Log Ωcm), the charge holding force is large, and therefore the surface of the intermediate transfer belt 16 is charged by the transfer electric field in the primary transfer, so a static elimination mechanism is necessary. It may become.
The common logarithmic value of the volume resistivity can be controlled by the type of CB and the amount of CB added as described above.

In the present embodiment, the volume resistivity can be measured according to JIS K6911 (1995) using a circular electrode (for example, UR probe of Hiresta IP manufactured by Mitsubishi Oil Chemical Co., Ltd.). The measurement can be performed with the same device as the surface resistivity.
The circular electrode includes a first voltage application electrode A and a second voltage application electrode B in place of the plate-like insulator at the time of measuring the surface resistivity. The first voltage application electrode A includes a cylindrical electrode portion C. The measurement target T is sandwiched between the cylindrical electrode part C and the second voltage application electrode B in the first voltage application electrode A, and the cylindrical electrode part C and the second voltage application electrode B in the first voltage application electrode A The current I (A) that flows when the voltage V (V) is applied during the measurement is measured, and the volume resistivity ρv (Ωcm) of the measurement target T can be calculated by the following equation (2). Here, in the following formula (2), t indicates the thickness of the measurement target T.
Formula (2) ρv = πd ² / 4t × (V / I)

(Young's modulus)
The intermediate transfer belt 16 preferably has a Young's modulus of 1000 MPa or more, and more preferably 1500 MPa or more.

The Young's modulus E can be calculated from the following formula (3) by measuring the force ΔS applied to the unit cross-sectional area and the elongation Δa in the unit length.
Formula (3) E = ΔS / Δa
Here, ΔS is expressed by ΔS = F / (w × t) from the load F, the film thickness t of the sample, and the sample width w, and Δa is from the sample reference length L and the sample elongation ΔL when the load is applied. , Δa = ΔL / L, and is measured as follows.

  First, the measurement target T was cut into 80 mm × 5 mm. The Young's modulus was measured 10 times, and the average value was used as measurement data. The measuring machine used was a tensile tester MODEL-1605N manufactured by Aiko Engineering Co., Ltd., and the measuring conditions were 22 ° C. and 55% environment, and the tensile speed was 20 mm / min. In addition, the belt film thickness required for belt cross-sectional area calculation used the average value measured 5 times by the eddy current type film thickness meter CTR-1500E by Sanko Electronics.

(Thickness)
The total thickness of the intermediate transfer belt 16 is usually 0.05 mm to 0.5 mm, preferably 0.06 mm to 0.30 mm, and more preferably 0.06 mm to 0.15 mm. If the total thickness of the belt is less than 0.05 mm, the intermediate transfer belt 16 may not satisfy the required mechanical characteristics. If the thickness exceeds 0.5 mm, the belt surface stress may be caused by deformation at the roll bending portion. In some cases, such as the concentration of cracks, cracks may occur in the surface layer.

(Surface micro hardness)
In the intermediate transfer belt 16, the transfer surface of the intermediate transfer belt 16 is deformed by the pressing force of the bias roller, and the hardness of the transfer surface affects the holocharacter in which the line image is lost. The microhardness is preferably 30 or less, and more preferably 25 or less.

The surface microhardness can be determined by a method of measuring how much the indenter has entered the sample. When the test load P (mN) and the amount of penetration of the indenter into the sample (indentation depth) D (μm), the surface microhardness DH is defined by the following formula (4).
Formula (4) DH≡αP / D ²
Here, α is a constant depending on the shape of the indenter, and α = 3.8854 (used indenter: in the case of a triangular pyramid indenter).

The surface microhardness of the intermediate transfer belt was determined by the following method. The intermediate transfer belt is cut to about 5 mm square, and the small piece is fixed to the glass plate with an instantaneous adhesive. The surface microhardness of the surface of this sample is measured using an ultra micro hardness meter DUH-201S (manufactured by Shimadzu Corporation). The measurement conditions are as follows.
Measurement environment: 22 ° C, 55% RH
Working indenter: Triangular pyramid indenter Test mode: 3 (soft material test)
Test load: 0.70 gf
Load speed: 0.0145 gf / sec
Holding time: 5 sec

  The intermediate transfer belt 16 in the present embodiment is preferably used in the color image forming apparatus 100 capable of high-speed printing. The printing speed is the speed of each member used in the image forming apparatus, that is, the conveying speed of each member involved in transferring the toner image to the image carrier, intermediate transfer belt, and recording medium in the apparatus. However, the intermediate transfer belt 16 according to the present exemplary embodiment also has density unevenness and spots even when the conveyance speed of these members is 200 mm / sec or more. State defects can be reduced. Even if the conveyance speed is less than 200 mm / sec, an image can be formed satisfactorily.

  Further, primary transfer from the photoreceptor 9 to the intermediate transfer belt 16 is an important factor in determining the quality of the final image. It is required that there is no primary transfer efficiency or image disturbance at the time of transfer, and a high transfer current value is desirable. When the conveyance speed of the intermediate transfer belt 16 is 200 mm / sec or more, the primary transfer current value is preferably 25 μA or more, and more preferably 30 μA or more.

  The semiconductive polyamide-imide belt according to the present embodiment can be used in various forms of image forming apparatuses in addition to the color image forming apparatus as described above, for example, electrophotographic copying machines, laser printers, facsimiles. It can be used for image forming apparatuses such as these composite OA devices.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.

[Synthesis Example 1]
In a 3-liter four-necked flask, 384.2 g (2.0 mol) of trimellitic anhydride, 210.4 g (1.0 mol) of naphthalene-2,6-diisocyanate, 250.4 g of 4,4′-diphenylmethane diisocyanate ( 1.0 mol) and 2000 g of N-methyl-2-pyrrolidone were charged, heated to 120 ° C. under a nitrogen stream, and reacted for about 5 hours to obtain a PAI resin solution having a number average molecular weight of 26,000. This PAI resin solution was diluted with N-methyl-2-pyrrolidone to obtain a PAI resin solution- (I) having a viscosity of 7.0 Pa · s and a nonvolatile content of 21.3%.

[Synthesis Example 2]
A 3 liter four-necked flask was charged with 384.2 g (2.0 mol) of trimellitic anhydride, 500.8 g (1.0 mol) of 4,4′-diphenylmethane diisocyanate and 1650 g of N-methyl-2-pyrrolidone, The temperature was raised to 130 ° C. under a nitrogen stream and reacted for 4 hours to obtain a PAI resin solution having a number average molecular weight of 27,000. This PAI resin solution was diluted with N-methyl-2-pyrrolidone to obtain a PAI resin solution- (II) having a viscosity of 3.7 Pa · s and a nonvolatile content of 26.1%.

[Example 1]
PAI resin solution- (I) 1600 parts, dried 62 parts of oxidized CB-1 (SPECIAL BLACK4, manufactured by Degussa, specific surface area: 180 (m ² / g), DBP oil absorption: 280 (cc / 100 g) Volatile content: 14.0%, hereinafter referred to as “oxidized CB-1”) and 62 parts of oxidized carbon black-2 (SPECIAL BLACK250, manufactured by Degussa, Inc.). 40 (m ² / g), DBP oil absorption: 48 (cc / 100 g), volatile content: 2.0%, hereinafter the same as “oxidation treatment CB-2”), polyvinylpyrrolidone (manufactured by BASF Japan) , K17) Add 10 parts, disperse with a wet jet mill disperser (Geanus PY) (150MPa, 5pass) To obtain a carbon black dispersion polyamideimide solution. This was passed through a stainless steel 20 μm mesh to remove foreign substances and carbon black aggregates. Further, vacuum defoaming was performed for 15 minutes with stirring to prepare a final coating solution.
Next, the obtained polyamideimide solution in which carbon black is dispersed is applied to the outer surface of the cylindrical mold (outer diameter 168 mm, length 500 mm, wall thickness 10 mm) so that the thickness becomes about 0.5 mm by the ring float method. After coating and rotating at 250 rpm for 15 minutes to form a spread layer having a uniform thickness, the film was heated at 60 ° C. for 30 minutes while being rotated at 250 rpm, and then heated at 250 ° C. for 60 minutes. After cooling to room temperature and demolding, the desired polyamideimide belt- (1) (intermediate transfer belt) was obtained (a belt was created immediately after the coating solution was prepared).
The belt thickness was about 80 μm. Various characteristics of the obtained belt were evaluated. The results are shown in Table 1.

[Example 2]
In 300 parts of N-methyl-2pyrrolidone (NMP), 70 parts of dried oxidized CB-1, 70 parts of dried CB-2, and 10 parts of polyvinylpyrrolidone (manufactured by BASF Japan, K17) were added. In addition, the mixture was mixed with a ball mill at room temperature for 6 hours to prepare a carbon black-dispersed NMP solution.
Next, 400 parts of the carbon black-dispersed NMP solution was added to 1700 parts of PAI resin solution- (I) and stirred at 25 ° C. and 50 rpm for 10 hours. This was passed through a stainless steel 20 μm mesh to remove foreign substances and carbon black aggregates. Further, vacuum defoaming was performed for 15 minutes with stirring to prepare a final coating solution.
Using this coating solution, a polyamideimide belt (2) was obtained in the same manner as in Example 1 (a belt was created immediately after the coating solution was prepared).
Various characteristics of the obtained belt were evaluated. The results are shown in Table 1.

[Example 3]
In 300 parts of N-methyl-2pyrrolidone (NMP), 70 parts of dried oxidized CB-1, 70 parts of dried CB-2, and 10 parts of polyvinylpyrrolidone (manufactured by BASF Japan, K17) were added. In addition, the mixture was mixed with a ball mill for 6 hours at room temperature to prepare a carbon black-dispersed NMP solution.
Next, 400 parts of this solution was placed in a 3 liter four-necked flask and 229.5 g (1.195 mol) of trimellitic anhydride and 125.7 g (0.598 mol) of naphthalene-2,6-diisocyanate, 4 , 4′-diphenylmethane diisocyanate 149.6 g (0.598 mol) and N-methyl-2-pyrrolidone 1195 g were heated to 120 ° C. under a nitrogen stream and reacted for about 5 hours to give a number average molecular weight of 26,000. A PAI resin solution was obtained. This was passed through a stainless steel 20 μm mesh to remove foreign substances and carbon black aggregates. Further, vacuum defoaming was performed for 15 minutes with stirring to prepare a final coating solution.
Using this coating solution, a polyamideimide belt (3) was obtained in the same manner as in Example 1 (a belt was prepared immediately after the coating solution was prepared).
Various characteristics of the obtained belt were evaluated. The results are shown in Table 1.

[Example 4]
A polyamideimide belt (4) was obtained in the same manner as in Example 3 except that 50 parts of the oxidation treatment CB-1 and 90 parts of the oxidation treatment CB-2 were used. created).
Various characteristics of the obtained belt were evaluated. The results are shown in Table 1.

[Example 5]
A polyamideimide belt (5) was obtained in the same manner as in Example 1 except that the PAI resin solution (II) was used (a belt was prepared immediately after the coating solution was prepared).
Various characteristics of the obtained belt were evaluated. The results are shown in Table 1.

[Example 6]
Polyamideimide belt (6) was obtained in the same manner as in Example 1 except that 10 parts of poly (N-vinylphthalamide) (Aldrich) was used instead of 10 parts of polyvinylpyrrolidone (solution for coating) The belt was created immediately after the production of
Various characteristics of the obtained belt were evaluated. The results are shown in Table 1.

[Comparative Example 1]
A polyamideimide belt (7) was obtained in the same manner as in Example 4 except that 10 parts of polyvinylpyrrolidone was not used (a belt was prepared immediately after the application solution was prepared).
Various characteristics of the obtained belt were evaluated. The results are shown in Table 1.

[Comparative Example 2]
A polyamideimide belt- (8) was obtained in the same manner as in Example 5 except that 10 parts of polyvinylpyrrolidone was not used (a belt was prepared immediately after preparation of the coating solution).
Various characteristics of the obtained belt were evaluated. The results are shown in Table 1.

[Examples 7 to 12, Comparative Examples 3 and 4]
The polyamide-imide belts of Examples 1 to 6 and Comparative Examples 1 and 2 were incorporated into a modified DocuCentreColor 2220 manufactured by Fuji Xerox Co., Ltd. (process speed: 250 mm / sec, primary transfer current: modified to 35 μA), and high temperature and high Output 50% halftone of Cyan and Magenta to C2 paper made by Fuji Xerox at low humidity (32 ° C, 85% RH) and low temperature and low humidity (5 ° C, 15% RH). Was visually evaluated. The results are shown in Table 2.

[Density unevenness]
A: Density unevenness is not confirmed in the output halftone.
◯: A slight density unevenness could be confirmed in the output halftone, but it was a level with no problem.
X: Density unevenness was clearly confirmed in the output halftone.
[Speckle defect]
A: No spot defect is confirmed in the output halftone.
○: A slight spot defect was confirmed in the output halftone, but it was at a level with no problem.
×: Spot defects were clearly confirmed in the output halftone.

[Examples 13 to 18, Comparative Examples 5 and 6]
Polyamides were prepared in the same manner as in Examples 1 to 6 and Comparative Examples 1 and 2, except that each solution was blended to prepare a coating solution, each coating solution was stored at room temperature, and a belt was formed after one week. Imide belt (9) to polyamideimide belt (16) were obtained.
Various characteristics of the obtained belt were evaluated. The results are shown in Table 3.

[Examples 19 to 24, Comparative Examples 7 and 8]
Using the polyamideimide belt- (9) to the polyamideimide belt- (16), density unevenness and speckle defects were evaluated in the same manner as in Examples 7-12 and Comparative Examples 3 and 4. The results are shown in Table 4.

From the results in Tables 1 to 4, the following matters can be read.
(A) By comparison between Examples and Comparative Examples, the semiconductive polyamideimide belt of the present embodiment containing a polyamideimide resin, a polymer dispersant, and conductive fine particles does not contain a polymer dispersant. As compared with the semiconductive polyamideimide belt, an intermediate transfer belt with reduced density unevenness and speckle defects, and thus an image forming apparatus can be realized.
(B) By comparing Example 1 with Example 5 or comparing Example 13 with Example 17, the molecular structure of the PAI resin is a structure having units derived from a plurality of diisocyanate components. Thus, density unevenness can be further reduced.
(C) An intermediate transfer belt in which density unevenness and speckle defects are reduced by comparison between Example 1 and Example 6 or between Example 13 and Example 18 regardless of the type of polymer dispersant. Can be realized.
(D) Comparison between Example 3 and Example 4 or comparison between Example 15 and Example 16 realizes an intermediate transfer belt with reduced density unevenness and spot defects regardless of the amount of carbon black. Can be done.
Comparison (e) of Example 2 and Example 14 or a comparison between Example 3 and Example 15, after mixing the polymer dispersing agent and conductive fine particles in a solvent, a polyamideimide precursor It can be seen that the composition obtained by polymerization is more excellent in the stability of the coating solution than the composition obtained by simultaneously dissolving the previously formed polyamideimide resin and the polymer dispersant / conductive fine particles.

1 is a schematic configuration diagram illustrating a color image forming apparatus to which the exemplary embodiment is applied. It is the schematic plan view (a) and schematic sectional drawing (b) which show an example of a circular electrode.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Toner cartridge, 2 ... Fixing roll, 3 ... Backup roll, 4 ... Tension roll, 5 ... Secondary transfer roll, 6 ... Paper path, 7 ... Paper tray, 8 ... Laser generator, 9 ... Photoconductor, 10 ... Primary transfer roll, 11 ... Drive roll, 12 ... Transfer cleaner, 13 ... Charging roll, 14 ... Photoconductor cleaner, 15 ... Developer, 16 ... Intermediate transfer belt, 100 ... Color image forming apparatus

Claims (4)

A polyamide-imide resin;
Conductive fine particles blended in the range of 10% by mass to 30% by mass with respect to the resin solid content of the polyamide-imide resin;
A polymer dispersant comprising a polyamide compound having an N-vinyl group in a molecular structure blended in a range of 0.01 to 3 parts by mass with respect to 10 parts by mass of the conductive fine particles;
Measured according to JIS K6911 using a circular electrode and calculated by the following formula (1) , the difference between the common logarithmic value of the surface resistivity after 10 seconds of voltage application and the common logarithm of the surface resistivity after 30 msec is an absolute value. A semiconductive polyamide-imide belt characterized by being 0.7 (LogΩ / □) or less.
Formula (1) ρs = π × (D + d) / (D−d) × (V / I)
(In formula (1), ρs is the surface resistivity, d is the outer diameter (d: mm) of the cylindrical electrode provided in the circular electrode, and D is the inner diameter (D: mm) of the ring electrode provided in the circular electrode. Yes, V is voltage (V), and I is current (A).) An image carrier;
Charging means for charging the surface of the image carrier;
Latent image forming means for forming a latent image on the surface of the image carrier;
Developing means for developing the latent image with toner to form a toner image;
First transfer means for primary transfer of the toner image to an intermediate transfer belt;
Second transfer means for secondary transfer of the toner image transferred to the intermediate transfer belt to a transfer target;
Fixing means for fixing the toner image to a transfer object;
The intermediate transfer belt is
Polyamideimide resin, conductive fine particles blended in the range of 10% by mass to 30% by mass with respect to the resin solid content of the polyamideimide resin, and 0.01 parts by mass to 3% by mass with respect to 10 parts by mass of the conductive fine particles. A polymer dispersant comprising a polyamide compound having an N-vinyl group in the molecular structure blended in a range of parts,
Measured according to JIS K6911 using a circular electrode and calculated by the following formula (1) , the difference between the common logarithmic value of the surface resistivity after 10 seconds of voltage application and the common logarithm of the surface resistivity after 30 msec is an absolute value. An image forming apparatus, which is a semiconductive polyamide-imide belt having a value of 0.7 (LogΩ / □) or less.
Formula (1) ρs = π × (D + d) / (D−d) × (V / I)
(In formula (1), ρs is the surface resistivity, d is the outer diameter (d: mm) of the cylindrical electrode provided in the circular electrode, and D is the inner diameter (D: mm) of the ring electrode provided in the circular electrode. Yes, V is voltage (V), and I is current (A).) After the conductive fine particles are dispersed in a solution in which a polymer dispersant composed of a polyamide compound having an N-vinyl group in the molecular structure is dissolved, the polyamideimide resin is further dissolved to form a coating solution. The liquid was heated and dried, measured according to JIS K6911 using a circular electrode, and calculated according to the following formula (1) : the common logarithm of the surface resistivity after 10 seconds of voltage application and the common surface resistivity after 30 msec A method for producing a semiconductive polyamide-imide belt, comprising obtaining a semi-conductive polyamide-imide belt having a difference from a logarithmic value of 0.7 (LogΩ / □) or less in absolute value.
Formula (1) ρs = π × (D + d) / (D−d) × (V / I)
(In formula (1), ρs is the surface resistivity, d is the outer diameter (d: mm) of the cylindrical electrode provided in the circular electrode, and D is the inner diameter (D: mm) of the ring electrode provided in the circular electrode. Yes, V is voltage (V), and I is current (A).) After dispersing the conductive fine particles in a solution in which a polymer dispersant composed of a polyamide compound having an N-vinyl group in the molecular structure is dissolved, the monomer that is a precursor of the polyamide-imide resin is dissolved, and further the monomer Of the surface resistivity after 10 seconds of voltage application, measured according to JIS K6911 using a circular electrode, and calculated by the following formula (1) by heating and drying the coating liquid. A semiconductive polyamide-imide belt having a difference between a common logarithm value and a common log value of a surface resistivity after 30 msec of 0.7 (LogΩ / □) or less is obtained. A method for manufacturing a belt.
Formula (1) ρs = π × (D + d) / (D−d) × (V / I)
(In formula (1), ρs is the surface resistivity, d is the outer diameter (d: mm) of the cylindrical electrode provided in the circular electrode, and D is the inner diameter (D: mm) of the ring electrode provided in the circular electrode. Yes, V is voltage (V), and I is current (A).)

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