JP2015106022A - Endless belt and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endless belt including a base layer capable of improving the durability compared with the conventional art.SOLUTION: The endless belt 1 includes at least a cylindrically formed base layer 2. The base layer 2 is produced by using (a) an aromatic isocyanate compound, (b) an anhydride of aromatic polyvalent carboxylic acid, and (c) a polyamide-imide resin made of a copolymer containing each polymerization unit by a hindered phenolic antioxidant and/or a hindered amine system antioxidant.

Description

  The present invention relates to an endless belt and a manufacturing method thereof.

  Conventionally, endless belts are used in various fields. For example, in the field of image forming apparatuses such as copying machines, printers, and printing machines that employ an electrophotographic method, each toner image formed by a plurality of photoconductors for each color is primarily transferred onto the belt surface, and the toner images of each color are superimposed. In addition, an endless belt is used as an intermediate transfer belt for secondary transfer to a transfer material such as paper. In addition, an endless belt is used as a fixing belt for forming an image by melting and fixing toner transferred to a transfer material (paper) by heating.

  As the endless belt, an endless belt having a base layer formed using a polyamideimide resin having relatively high rigidity is widely known.

  For example, Patent Document 1 discloses an endless belt having a base layer having a sea-island structure in which an island phase made of a silicone polymer is micro-dispersed in a sea phase made of a polyamideimide resin.

  For example, Patent Document 2 discloses an endless belt having a base layer formed using a modified polyamideimide resin obtained by copolymerizing an aromatic isocyanate compound, an aromatic polycarboxylic acid anhydride, and a silicone polymer. Has been.

  Note that Patent Literature 3 preceding this application discloses a technique of adding an antioxidant to a synthesized polyamideimide resin. Patent Document 4 preceding this application discloses a technique for producing a polyamide-imide elastomer by charging caprolactam, polyoxytetramethylene glycol, trimellitic anhydride, diphenylmethane diisocyanate together with an antioxidant and heating them. ing.

Japanese Patent No. 4622584 JP 2006-47587 A JP-A-2-117957 Japanese Patent Publication No. 8-5943

  However, the conventionally known endless belts have room for improvement in the following points. That is, in the field of an image forming apparatus in which an endless belt is incorporated, there is a great demand for high durability of the apparatus. Therefore, the endless belt used for this is also required to be further improved in durability.

  However, as in the prior art, the method of dispersing the silicone polymer in the polyamideimide resin constituting the base layer has a limit in the amount of silicone polymer added, and the problem is that the durability of the silicone polymer deteriorates if the silicone polymer dispersibility deteriorates. There is. In addition, it is difficult to control the dispersion of the silicone polymer. Therefore, there is a limit to further improving the durability of the base layer. In addition, there is a method of copolymerizing a silicone polymer in a polyamideimide resin, but even with this method, it is difficult to improve the durability of the base layer more than ever.

  As a method other than the above, a method in which an antioxidant is added after the synthesis of the polyamideimide resin and this is used for the base layer of the endless belt can be considered. However, in this method, the polyamideimide resin is thermally aged by the heat treatment at the time of synthesizing the polyamideimide resin or forming the base layer. Therefore, it is difficult to further improve the durability of the base layer even with this method.

  The present invention has been made in view of the above-described background, and has been obtained in an attempt to provide an endless belt having a base layer capable of further improving durability as compared with the conventional art.

One aspect of the present invention is an endless belt having at least a base layer formed in a cylindrical shape,
The base layer is an endless belt which is formed using a polyamide-imide resin made of a copolymer containing polymerized units of the following components (a) to (c).
(A) aromatic isocyanate compound (b) aromatic polyhydric carboxylic acid anhydride (c) hindered phenolic antioxidant and / or hindered amine antioxidant

Another aspect of the present invention is a polyamide-imide resin comprising a copolymer containing the respective polymerized units of the above components (a) to (c) by heat-reacting the following components (a) to (c) in an organic solvent: And a coating liquid preparation step of preparing a base layer forming coating liquid containing the polyamideimide resin and the organic solvent,
A base layer forming step of forming a cylindrical base layer by applying the base layer forming coating liquid to the outer peripheral surface of a cylindrical or columnar mold, and then heat-treating the coating liquid,
It is in the manufacturing method of the endless belt characterized by having.
(A) aromatic isocyanate compound (b) aromatic polyhydric carboxylic acid anhydride (c) hindered phenolic antioxidant and / or hindered amine antioxidant

  The endless belt has the above configuration. In particular, the endless belt is made of a copolymer in which the polyamideimide resin constituting the base layer includes polymerized units of (c) a hindered phenol-based antioxidant and / or a hindered amine-based antioxidant. Therefore, the endless belt is made of the polyamideimide resin at the time of synthesizing the polyamideimide resin in the production thereof, and at the time of forming the base layer for forming the base layer by heat-treating the base layer forming coating liquid containing the synthesized polyamideimide resin. Thermal deterioration is suppressed and heat resistance is improved. Therefore, the endless belt can further improve the durability of the base layer as compared with the conventional endless belt. Further, the endless belt has an advantage that an antioxidant is incorporated as a polymerization unit in the molecule of the polyamide-imide resin, so that the counterpart member is hardly contaminated with the antioxidant.

  The endless belt is produced by synthesizing a polyamide-imide resin comprising a copolymer containing polymerized units of (c) a hindered phenol-based antioxidant and / or a hindered amine-based antioxidant in the coating liquid preparation step. Therefore, the endless belt manufacturing method suppresses thermal degradation of the polyamideimide resin due to heat during synthesis. Further, in the above-described base layer forming step, the endless belt manufacturing method comprises heat-treating a base layer forming coating solution containing a polyamideimide resin containing a polymerized unit of the component (c) in the molecule, from the polyamideimide resin. A base layer is formed. Therefore, the endless belt manufacturing method suppresses the thermal degradation of the polyamideimide resin due to the heat when forming the base layer. Therefore, the manufacturing method of the endless belt is to manufacture an endless belt having a base layer that is further improved in durability as compared with the prior art by suppressing heat deterioration of the polyamideimide resin and improving heat resistance. Can do.

  In addition, the endless belt manufacturing method does not mainly improve the durability by dispersing the silicone polymer. Therefore, the durability does not deteriorate due to the deterioration of the dispersibility, and the highly difficult dispersion control is unnecessary. be able to. Further, the above endless belt manufacturing method is advantageous in manufacturing an endless belt in which an antioxidant is not easily contaminated with an antioxidant because no antioxidant is added after the synthesis of the polyamideimide resin.

It is explanatory drawing which showed typically the endless belt of an Example. It is explanatory drawing which showed typically the II-II cross section of FIG.

  In the endless belt (seamless belt), the base layer is configured by using a polyamideimide resin made of a copolymer containing each polymer unit of the components (a) to (c). That is, the polyamideimide resin constituting the base layer contains at least a polymer unit based on the component (a), a polymer unit based on the component (b), and a polymer unit based on the component (c) in the molecule.

  The aromatic isocyanate compound as the component (a) is an isocyanate compound having an aromatic ring in the molecule. Examples of the aromatic isocyanate compound include diphenylmethane diisocyanate (MDI), tolidine diisocyanate (TODI), toluene diisocyanate (TDI), xylylene diisocyanate (XDI), lysine diisocyanate (LDI), naphthalene diisocyanate (NDI), paraphenylene diisocyanate ( PPDI), tetramethylxylene diisocyanate (TMXDI) and the like can be exemplified. These can be used alone or in combination of two or more. As the aromatic isocyanate compound, diphenylmethane diisocyanate (MDI) and tolidine diisocyanate (TODI) can be preferably used from the viewpoints of reactivity, solubility, cost, and the like.

  Specifically, the aromatic polyvalent carboxylic acid anhydride as the component (b) has an aromatic ring in the molecule and can undergo a condensation reaction with the aromatic isocyanate compound as the component (a). Can be used. Examples of the aromatic polyvalent carboxylic acid anhydride include aromatic polyvalent carboxylic acid anhydrides and aromatic polyvalent carboxylic acid dianhydrides. These can be used alone or in combination of two or more.

  Examples of the aromatic polyvalent carboxylic acid anhydride include trimellitic anhydride (trimellitic anhydride), naphthalene-1,2,4-tricarboxylic anhydride, and the like. These can be used alone or in combination of two or more. As the aromatic polyvalent carboxylic acid anhydride, trimellitic anhydride (trimellitic anhydride) can be suitably used from the viewpoints of reactivity, solubility, cost, and the like.

  Examples of the aromatic polycarboxylic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA), benzene-1,2,4,5-tetra Carboxylic dianhydride (pyromellitic dianhydride), benzophenone-3,3 ', 4,4'-tetracarboxylic dianhydride, diphenyl ether-3,3', 4,4'-tetracarboxylic dianhydride , Benzene-1,2,3,4-tetracarboxylic dianhydride, biphenyl-3,3 ', 4,4'-tetracarboxylic dianhydride, biphenyl-2,2', 3,3'- Tetracarboxylic dianhydride, naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8 -Tetracarboxylic dianhydride, deca Dronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic Acid dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2 , 3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, phenanthrene-1,3,9,10-tetracarboxylic dianhydride, perylene-3,4,9 , 10-tetracarboxylic dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 1,1-bis (2,3- Dicarboxyphenyl) ethane dianhydride 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, 2,3-bis (3,4-dicarboxy) Phenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylene glycol bis (anhydrotrimellitate), propylene glycol Bis (anhydro trimellitate) and the like can be exemplified. These can be used alone or in combination of two or more. As the aromatic polycarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride can be preferably used from the viewpoint of reactivity, solubility, cost, and the like. .

  The hindered phenol-based antioxidant and / or hindered amine-based antioxidant as the component (c) is an important component for further improving the durability of the base layer. As the component (c), a hindered phenol-based antioxidant can be preferably used from the viewpoint that it is easy to further improve the durability of the base layer and the reactivity is optimal.

  Examples of the hindered phenol antioxidant include N, N′-hexane-1,6-diylbis [3- (3,5-di-t-butyl-4-hydroxyphenylpropionamide)], 4, 4′-thiobis (3-methyl-6-tertiarybutylphenol), 4,4′-butylidenebis (2-tertiarybutyl-5-methylphenol), 4,4 ′, 4 ″-[(2,4,4 6-tri) methylbenzene-1,3,5-triyl] tris (methylene)] tris (2,6-di-tertiarybutylphenol) and the like. These can be used alone or in combination of two or more. As the hindered phenol-based antioxidant, N, N′-hexane-1,6-diylbis [3- (3,5] is preferable from the viewpoint of good reactivity and easy improvement of durability. -Di-t-butyl-4-hydroxyphenylpropionamide)], 4,4 ′, 4 ″-[(2,4,6-tri) methylbenzene-1,3,5-triyl] tris (methylene) ] Tris (2,6-di-tertiary butylphenol) and the like can be suitably used.

  The component (c) can also be used in combination with a phosphorus-based antioxidant (phosphorus-based processing stabilizer). In this case, since the phosphorus antioxidant further supplements the radicals captured by the hindered phenol antioxidant and the hindered amine antioxidant, the MIT durability is improved, and the base layer of the endless belt is further improved. There is an advantage that durability can be easily improved.

Examples of the phosphorus antioxidant include tris (2,4-di-t-butylphenyl) phosphite), 3,9-bis (2,6-ditertiarybutyl-4-methylphenoxy)- Examples include 2,4,8,10-tetraoxa-3,9-diphosphaspiro [5,5] undecane-triphenyl phosphite, octadecyl phosphite, and the like. These can be used alone or in combination of two or more. From the viewpoint that the effect of the combined use with the hindered phenol antioxidant or the hindered amine antioxidant is great, tris (2,4-di-t-butylphenyl) phosphite), 3,9-bis (2 , 6-di-tertiarybutyl-4-methylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5,5] undecane-triphenol phosphite and the like can be suitably used.

  In the endless belt, the polyamide-imide resin further comprises (d) the copolymer including a polymer unit of a polydimethylsiloxane compound and / or (d) contains a polydimethylsiloxane compound. Can do. That is, the polyamide-imide resin may further contain a polymer unit based on the component (d) in the molecule, or a polydimethylsiloxane compound may be dispersed and mixed, or both. May be.

  In this case, an appropriate stress relaxation effect is imparted to the base layer, the MIT durability of the base layer is improved, and the flex resistance of the base layer is improved. Therefore, in this case, there is an advantage that it is easy to further improve the durability of the base layer in the endless belt due to a synergistic effect with the inclusion of the polymer unit of the component (c) in the molecule.

  As the polydimethylsiloxane compound, for example, a silicone polymer having a polydimethylsiloxane structure in the molecule can be used. As the polydimethylsiloxane compound, specifically, a compound having a reactive group that reacts with the isocyanate group of the aromatic isocyanate compound is used from the viewpoint of easy incorporation into the molecule during the synthesis of the polyamideimide resin. More specifically, those having one reactive group at both ends and those having two reactive groups at one end can be suitably used. These can be used alone or in combination of two or more. Examples of the reactive group include a hydroxyl group, a carboxyl group, and an amino group. The polydimethylsiloxane compound is preferably a carboxylic acid both-end silicone polymer having one carboxyl group at both ends, a one-end bifunctional silicone polymer having two hydroxyl groups at one end, and the like.

  In the above endless belt, the polyamideimide resin may further comprise (e) the above copolymer containing polymerized units based on both terminal polymers of carboxylic acid. That is, the polyamideimide resin may further include a polymer unit based on the component (e) in the molecule.

  In this case, moderate flexibility is imparted to the base layer, the MIT durability of the base layer is improved, and the bending resistance of the base layer is improved. Therefore, in this case, there is an advantage that it is easy to further improve the durability of the base layer in the endless belt due to a synergistic effect with the inclusion of the polymerized unit of the component (e) in the molecule.

  As said carboxylic acid both terminal polymer, what has 1 each carboxylic acid at the terminal of a polymer etc. can be used, for example. Specific examples of the carboxylic acid terminal polymer include carboxylic acid terminal polybutadiene, carboxylic acid terminal hydrogenated polybutadiene, carboxylic acid terminal polyester, carboxylic acid terminal polyamide, carboxylic acid terminal polyacrylonitrile-butadiene copolymer. A coalescence etc. can be illustrated. These can be used alone or in combination of two or more. Examples of the carboxylic acid used for introducing the carboxylic acid at both ends of the polymer include adipic acid, sebacic acid, suberic acid, oxalic acid, succinic acid, corkic acid, azelaic acid, dodecanedicarboxylic acid, undecanedicarboxylic acid, Examples thereof include aliphatic carboxylic acids such as maleic acid, fumaric acid and itaconic acid, and aromatic carboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, chlorophthalic acid and nitrophthalic acid. These can be used alone or in combination of two or more.

  In the endless belt, the polymerized units of the component (c) in the polyamideimide resin can be in the range of 0.0005 mol% to 2.5 mol%.

  In this case, the incorporation amount of the antioxidant into the polyamideimide resin molecule becomes moderate, and thermal degradation during the synthesis of the polyamideimide resin and the formation of the base layer is effectively suppressed, and further improvement of the durability of the base layer is ensured. It becomes easy to do things.

  From the viewpoint of ensuring improved durability, the polymerized unit by the component (c) in the polyamideimide resin is preferably 0.001 mol% or more, more preferably 0.002 mol% or more, and still more preferably 0. 0.004 mol% or more, and even more preferably 0.005 mol% or more. In addition, the polymerized unit by the component (c) in the polyamide-imide resin is preferably 2.4 mol% or less, more preferably less than 2.4 mol% from the viewpoint that durability tends to be deteriorated when there are excessive bonds other than amide bonds and imide bonds. Can be 2 mol% or less, more preferably 1.8 mol% or less, even more preferably 1 mol% or less, and even more preferably 0.5 mol% or less.

  In the endless belt, when the polyamideimide resin is composed of the copolymer further including (d) a polymer unit of a polydimethylsiloxane compound, the polymer unit of the component (d) in the polyamideimide resin further improves durability. From the viewpoint of being advantageous, it can be preferably 0.01 mol% or more, more preferably 0.03 mol% or more, and still more preferably 0.05 mol% or more. In addition, the polymerization unit based on the component (d) in the polyamideimide resin is preferably 5 mol% or less, more preferably 4 mol% or less, still more preferably 3 mol% or less, and even more preferably 1 from the viewpoint of securing rigidity. It can be made into mol% or less.

  In the endless belt, when the polyamideimide resin contains (d) a polydimethylsiloxane compound, the content of the polydimethylsiloxane compound is about 0.5 to 15 parts by mass with respect to 100 parts by mass of the polyamideimide resin. Preferably, it can be about 2-10 mass parts.

  In the endless belt, when the polyamideimide resin is composed of the copolymer further including (e) a polymerized unit of a carboxylic acid both terminal polymer, the polymerized unit of the component (e) in the polyamideimide resin further improves durability. From the viewpoint of being advantageous, it is preferably 0.001 mol% or more, more preferably 0.005 mol% or more, and still more preferably 0.01 mol% or more. In addition, the polymerization unit based on the component (e) in the polyamideimide resin is preferably 3 mol% or less, more preferably 1 mol% or less, and even more preferably 0.5 mol% or less, from the viewpoint of securing rigidity. it can.

  In the above endless belt, the base layer can contain a conductive agent in addition to the polyamide-imide resin, for example, in order to impart conductivity to the base layer.

The conductive agent may be either an electronic conductive agent or an ionic conductive agent, and may include both. Examples of the electronic conductive agent include carbon-based materials having shapes such as carbon black, carbon nanotubes, graphite, and powders, fibers; metal powders such as aluminum powder and stainless powder; conductive zinc oxide (c-ZnO) Examples thereof include conductive metal oxides such as conductive titanium oxide (c-TiO ₂ ), conductive iron oxide (c-Fe ₃ O ₄ ), and conductive tin oxide (c-SnO ₂ ). These can be used alone or in combination of two or more. Examples of the ionic conductive agent include quaternary ammonium salts, phosphate esters, sulfonates, aliphatic polyhydric alcohols, aliphatic alcohol sulfates, ionic liquids, and the like. These can be used alone or in combination of two or more.

  In addition to the conductive agent, the base layer can contain one or more kinds of various additives such as a flame retardant, a filler (such as calcium carbonate), and a leveling agent. The cylinder diameter and thickness of the base layer can be determined as appropriate according to the application (for example, the model and size of the image forming apparatus). The cylinder diameter of the base layer can be about 120 to 1000 mm, for example. The thickness of the base layer can be, for example, about 30 to 200 μm, preferably about 40 to 130 μm, more preferably about 60 to 100 μm.

  The endless belt can be used in an electrophotographic image forming apparatus. In this case, it is possible to contribute to improving the durability of the image forming apparatus. Examples of the image forming apparatus include an electrophotographic copying machine using a charged image, a printer, a facsimile machine, a multifunction machine, a POD (Print On Demand) apparatus, and the like.

  The endless belt may be composed of a single layer or a plurality of layers of two or more layers as long as it has at least the base layer. Specifically, the endless belt includes (1) a configuration composed of a single base layer, (2) a configuration including a base layer and a rubber elastic layer laminated on the base layer, and (3) a base layer and a laminate on the base layer. And (4) a base layer, a conductive layer laminated on the base layer, and a rubber elastic layer laminated on the conductive layer. The configurations (1) to (3) are suitable as an intermediate transfer belt in an electrophotographic image forming apparatus, for example. The configuration (4) is suitable as a fixing belt in an electrophotographic image forming apparatus, for example.

  The intermediate transfer belt performs image transfer in order to primarily transfer the toner image carried on the latent image carrier onto the belt surface, and then secondarily transfer the toner image from the belt surface to a transfer material such as paper. It is an endless belt built into the device.

  Examples of the rubber used in the rubber elastic layer include acrylonitrile-butadiene rubber, butadiene rubber, styrene-butadiene rubber, butyl rubber, chloroprene rubber, and silicone rubber. These can be used alone or in combination of two or more.

  The rubber elastic layer can contain the above-described conductive agent in order to impart conductivity. In addition to the conductive agent, the rubber elastic layer can contain one or more various additives such as a crosslinking agent, a flame retardant, a filler (calcium carbonate, etc.), and a leveling agent. The thickness of the rubber elastic layer can be determined in consideration of flexibility, flame retardancy, wear resistance, usage, and the like. The thickness of the rubber elastic layer can be, for example, about 10 to 1000 μm, preferably about 20 to 400 μm, and more preferably about 30 to 300 μm.

  The surface of the rubber elastic layer is subjected to a light irradiation treatment such as an ultraviolet irradiation treatment or a surface treatment with a surface treatment liquid containing one or more selected from a chlorine-containing compound, a fluorine-containing compound, and an isocyanate. Can do. In this case, since the toner releasability is improved, it becomes difficult for the toner to adhere to the surface of the rubber elastic layer, and the filming resistance can be improved. Therefore, this case is suitable as an intermediate transfer belt.

  In addition, when providing a surface layer on the said base layer surface, as a main polymer material for comprising a surface layer, it is possible to use various polymers, such as an acrylic resin and a polycarbonate-type resin, for example. The surface layer can contain the above-described conductive agent and various additives. The thickness of the surface layer can be, for example, about 0.05 to 20 μm, preferably about 0.1 to 15 μm, and more preferably about 1 to 10 μm.

  Next, a method for manufacturing the endless belt will be described. In the coating liquid preparation step, the polyamideimide resin is synthesized, for example, in the reaction vessel by mixing the components (a) to (c) and the organic solvent, and if necessary, the component (d) and the component (e). The reaction can be carried out by heating and stirring under a nitrogen stream. At this time, the reaction temperature can be about 100 to 190 ° C. In addition, (d) component and (e) component can also be added after the synthesis | combination of a polyamideimide resin. Thus, after synthesize | combining a polyamideimide resin, various additives, such as the said electrically conductive agent, are mix | blended suitably as needed, and the coating liquid for base layer formation can be prepared.

  Here, a nitrogen-containing organic solvent containing N can be suitably used as the organic solvent.

  The nitrogen-containing organic solvent containing N has high nucleophilicity. Therefore, in this case, it is easy to improve the reactivity at the time of synthesizing the polyamideimide resin, and it is easy to synthesize a polyamideimide resin composed of a copolymer containing each polymer unit by the components (a) to (c). There is.

  As said nitrogen-containing organic solvent, what has a boiling point in the range of 160-260 degreeC, Preferably it is 170-240 degreeC can be used suitably. This is because in the base layer forming step, the nitrogen-containing organic solvent can be easily removed by the heat treatment during the base layer formation.

  Examples of the nitrogen-containing organic solvent include N-methyl-2-pyrrolidone (NMP: boiling point 203 ° C.), N-ethyl-2-pyrrolidone (NEP: boiling point 218 ° C.), tetramethylurea (TMU: boiling point 177 ° C.). ), Hexamethylphosphoric triamide (HMP: boiling point 235 ° C.), dimethyl sulfoxide (DMSO: boiling point 189 ° C.), nitrobenzene (boiling point 210.9 ° C.), benzonitrile (boiling point 191 ° C.), N, N-dimethylaniline (boiling point). 194 ° C.). These can be used alone or in combination of two or more.

  Next, in the base layer forming step, specifically, the base layer forming material can be applied to the surface of a cylindrical or columnar mold. The coating method is not particularly limited, and examples thereof include a dispenser coating method, a dip coating method, a spray coating method, and a roll coating method. Preferably, the dispenser coating method and the spray coating method are preferable from the viewpoint of easy uniform thickness and good handleability. Specifically, the heat treatment after coating can be carried out under the condition of holding at about 150 ° C. to 300 ° C. for about 1 hour to 3 hours. Moreover, the said heating can be specifically performed by heating a metal mold | die.

  After the base layer is formed, the base layer and the mold are separated to obtain a single-layer endless belt. In the case of further laminating a rubber elastic layer or a surface layer, after forming the base layer, a rubber elastic layer forming coating liquid or a surface layer forming coating liquid may be subsequently applied, and heat treatment may be performed under optimum conditions. After that, if the base layer and the mold are separated, an endless belt having a two-layer structure having a rubber elastic layer or a surface layer on the base layer can be obtained.

  In addition, each structure mentioned above can be arbitrarily combined as needed, in order to acquire each effect etc. which were mentioned above.

  Hereinafter, an endless belt of an example and a manufacturing method thereof will be described with reference to the drawings.

As shown in FIGS. 1 and 2, the endless belt 1 of this example has at least a base layer 2 formed in a cylindrical shape. The base layer 2 is configured using a polyamide-imide resin made of a copolymer containing polymerized units of the following components (a) to (c).
(A) aromatic isocyanate compound (b) aromatic polyhydric carboxylic acid anhydride (c) hindered phenolic antioxidant and / or hindered amine antioxidant

  In this example, the base layer 2 is made conductive by containing an electronic conductive agent. The endless belt 1 has a surface layer 3 laminated on the outer periphery of the base layer 2. The main material constituting the surface layer 3 is an acrylic resin, and the surface layer 3 is made conductive by containing an electronic conductive agent. The endless belt 1 is used as an intermediate transfer belt in an image forming apparatus such as a printer, a copier, a multifunction peripheral, or a POD (Print On Demand) apparatus that employs an electrophotographic system.

In the production method of the endless belt of this example, the above-described components (a) to (c) are heated and reacted in an organic solvent, and the polyamideimide is formed of a copolymer containing each polymer unit of the components (a) to (c). A coating liquid preparation step of synthesizing a resin and preparing a base layer forming coating liquid containing the polyamideimide resin and the organic solvent;
After the base layer forming coating liquid is applied to the outer peripheral surface of a cylindrical or columnar mold, the base layer forming step of forming a cylindrical base layer by heat treatment is included.

  In this example, after the base layer forming step, a surface layer forming step of forming a surface layer by further applying a surface layer forming coating liquid to the outer periphery of the base layer and performing heat treatment is further included.

  Hereinafter, a plurality of endless belt samples having different configurations were prepared and subjected to various evaluations. An experimental example will be described.

(Experimental example)
<Preparation of materials>
In synthesizing the polyamideimide resin used for the base layer in the endless belt of each sample, the following materials were prepared.
・ Diphenylmethane diisocyanate (MDI) (manufactured by Tokyo Chemical Industry Co., Ltd., reagent)
-Tolidine diisocyanate (TODI) (manufactured by Tokyo Chemical Industry Co., Ltd., reagent)
・ Trimellitic anhydride (trimellitic anhydride, TMA) (manufactured by Tokyo Chemical Industry Co., Ltd., reagent)
・ 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) (manufactured by Tokyo Chemical Industry Co., Ltd., reagent)
・ Ε-Caprolactam (manufactured by Ube Industries, “UBE caprolactam”)
・ Polydimethylsiloxane compound (one-end carbinol modified silicone oil) (JNC, “FM-DA21”)
Carboxylic acid both terminal polymer (both terminal COOH-modified NBR) (CVC Thermoset Specialties, “CTBN1300 × 13Na”)
・ Polyoxytetramethylene glycol ("PTMG1800" manufactured by Mitsubishi Chemical Corporation)
Hindered phenol antioxidant (N, N′-hexane-1,6-diylbis [3- (3,5-di-t-butyl-4-hydroxyphenylpropionamide)] (manufactured by BASF, “ IRGANOX 1098 ")
Phosphorus antioxidant (Tris (2,4-di-t-butylphenyl) phosphite)) ("IRGAFOS168" manufactured by BASF)

<Preparation of base layer forming coating solution>
In a reaction vessel equipped with a stirrer, a nitrogen introducing tube, a thermometer, and a cooling tube, each material in the blending ratio (parts by mass) shown in Table 1 and Table 2 described later (the one indicated as <addition during PAI synthesis>) And N-methyl-2-pyrrolidone (NMP) were charged to a solid content of 26%, the temperature was raised to 160 ° C. over 1 hour with stirring under a nitrogen stream, and the reaction was allowed to proceed at 160 ° C. for about 10 hours. The post-reaction was stopped, and a polyamideimide (PAI) -NMP solution (solid content concentration: 26% by mass) used for preparing endless belt samples of Sample 1 to Sample 12 was prepared.

  Further, the polyamideimide (PAI) -NMP solution used for preparing the endless belt sample of Sample 13 was prepared as follows. That is, each material (with <PAI synthesis added>) and N-methyl-2-pyrrolidone (NMP) in a blending ratio (parts by mass) shown in Table 2 to be described later and a solid content of 26%. Preparation and melting at 150 ° C. while flowing nitrogen at 50 ml / min, followed by polymerization reaction at 260 ° C. for 4 hours, the reaction was stopped, and polyamideimide (PAI) − used for preparation of the endless belt sample of Sample 13 An NMP solution (solid content concentration: 26% by mass) was prepared.

  Next, each PAI-NMP solution is blended at a predetermined part by mass with those indicated in Table 1 as <addition after PAI synthesis>, as necessary, with respect to 100 parts by mass of PAI. (25 ° C.) was mixed with a stirring blade.

  Next, each PAI-NMP solution was mixed with 4 parts by mass of carbon black (Showa Cabot Co., Ltd., “Show Black N220”) as an electronic conductive agent, and mixed with a stirring blade at room temperature (25 ° C.). It was dispersed using a ball mill. In this way, each base layer forming coating solution used for preparing endless belt samples of Samples 1 to 13 was prepared.

<Preparation of surface layer forming coating solution>
100 parts by mass of an acrylic resin (manufactured by Negami Kogyo Co., Ltd., “Paracron W-248E”), 30 parts by mass of a crosslinking agent (manufactured by Asahi Kasei Co., Ltd., “Duranate TPA-B80E”), and carbon black (Mitsubishi Chemical) as an electronic conductive agent Co., Ltd., “Carbon Black MA-100”) and 10 parts by mass of toluene and 500 parts by mass of toluene are mixed and mixed with a stirring blade, whereby a coating solution for forming a surface layer used for producing endless belt samples of Samples 1 to 13 Was prepared. The prepared surface layer forming coating liquid is of one type and is commonly used for the surface layer of the endless belt of each sample.

<Production of endless belt>
The adjusted base layer-forming coating solution is applied to the outer peripheral surface of the cylindrical mold by a spray coating method, and then heated from room temperature (25 ° C.) to 250 ° C. over 2 hours, and held at 250 ° C. for 1 hour. A heat treatment was performed to form a cylindrical base layer.

  Next, the prepared surface layer forming coating solution was applied to the surface of the base layer formed on the outer peripheral surface of the cylindrical mold by a dipping method and dried to form a surface layer.

  Next, the cylindrical mold was extracted by blowing air between the base layer and the cylindrical mold. Thus, endless belts of Samples 1 to 13 having a two-layer structure having a base layer (thickness 80 μm) formed in a cylindrical shape and a surface layer (thickness 6 μm) formed on the outer periphery of the base layer were produced. In addition, mol% of the polymerized units by (c) hindered phenolic antioxidant, (d) polydimethylsiloxane compound, (e) carboxylic acid both terminal polymer in the polyamide resin constituting the base layer of the endless belt is a blending ratio. It can be calculated from

<Measurement of tensile modulus>
In the preparation of the base layer-forming coating solution, each composition before the addition of the electronic conductive agent was applied to the surface of the polyimide film by a bar coating method, and then increased from room temperature (25 ° C.) to 250 ° C. over 2 hours. Heat treatment was performed by heating and holding at 250 ° C. for 1 hour to prepare each coating film sample (thickness: 80 μm). Then, based on JISK7127, the tensile elasticity modulus of each coating film sample was measured.

<Durability evaluation>
(1) MIT endurance test In preparation of the base layer-forming coating solution, each composition before the addition of the electronic conductive agent was applied to the surface of the polyimide film by a bar coating method, and then at room temperature (25 ° C) to 250 ° C. The film was heated up to 2 hours and held at 250 ° C. for 1 hour to prepare each coating film sample (thickness 80 μm). A strip-shaped test piece (15 mm × 115 mm) is cut out from each coating sample, and is used in a 25 ° C. × 45% RH environment, using an MIT folding fatigue tester (“MIT-DA” manufactured by Toyo Seiki Seisakusho Co., Ltd.). An MIT test was performed and the number of MITs was measured. The test conditions were a load of 0.25 kg with a spring interposed, a repetition rate of 175 cycles / min, and a swing angle of 90 °. The number of MITs serves as an index for evaluation of bending resistance, and the greater the number of MITs, the better the durability against bending.

(2) Belt endurance test Each endless belt is incorporated as an intermediate transfer belt for a commercially available multifunction printer (Fuji Xerox Co., Ltd., “DocuCentre-IV C2260”) that employs an electrophotographic system, and 50,000 color images are incorporated. Printed. Then, the damage state of each endless belt was examined. The case where no crack was observed was designated as “A” because it was excellent in belt durability. Moreover, although the crack was seen slightly, when it was in the tolerance | permissible_range, it was set as "B" as belt durability being favorable. The case where many cracks were observed was designated as “C” because the belt durability was inferior.

<Image evaluation>
Each endless belt was incorporated as an intermediate transfer belt of the multifunction printer, and a full color image was output. In the initial image, there was no color misalignment or color unevenness image defect and a good image was formed as “A”, and in the initial image a color misalignment or color unevenness image defect occurred as “C”. This evaluation is for confirming the usefulness as an intermediate transfer belt.

  Tables 1 and 2 collectively show the blending, evaluation results, and the like when producing endless belts for each sample.

  According to Tables 1 and 2, the following can be understood. That is, in the endless belts of Samples 9 to 11, the polyamide-imide resin constituting the base layer does not contain a polymer unit due to (c) a hindered phenol-based antioxidant and / or a hindered amine-based antioxidant. Therefore, in the endless belts of Samples 9 to 11, the polyamideimide resin was thermally aged by the heat treatment at the time of synthesizing the polyamideimide resin or forming the base layer, and the durability of the base layer could not be further improved. In addition, the endless belts of Samples 10 and 11 are obtained by adding a polydimethylsiloxane compound or a carboxylic acid both-end polymer at the time of synthesizing a polyamideimide resin. I know that there is.

  The endless belt of Sample 12 is obtained by adding a hindered phenolic antioxidant after the synthesis of the polyamideimide resin, and the polyamideimide resin constituting the base layer contains polymerized units of the hindered phenolic antioxidant. Not in. Therefore, in the endless belt of Sample 12, the polyamideimide resin was thermally aged by the heat treatment at the time of synthesizing the polyamideimide resin or forming the base layer, and the durability of the base layer could not be further improved.

The endless belt of Sample 13 synthesizes a polyamide-imide resin constituting the base layer by charging ε-caprolactam, polyoxytetramethylene glycol, trimellitic anhydride, diphenylmethane diisocyanate together with a hindered phenolic antioxidant and heating them. doing. It can be seen that the endless belt of the sample 13 has a component system different from that of the present application, and thus cannot further improve the durability of the base layer. This is considered to be due to the following reason. In sample 13, the strength of the nucleophilicity (reactivity) of the reactive groups present in the component system used for the synthesis is in the order of acid anhydride <COOH group <NCO group <OH group <NH ₂ group. In sample 13, the NH ₂ group having the strongest nucleophilicity is present in excess in the system, and it is considered that the NCO group and the COOH group react preferentially over the OH group. In addition, since the NH ₂ group and the OH group have strong nucleophilicity with each other, the possibility of the two reacting is low. Therefore, in sample 13, even when a hindered phenolic antioxidant is added during the synthesis of the polyamideimide resin, it is considered that the hindered phenolic antioxidant is hardly incorporated as a copolymerization component in the molecule of the polyamideimide resin. It is done. As a result, it is presumed that the endless belt of the sample 13 could not be further improved in durability of the base layer.

  On the other hand, the endless belts of Samples 1 to 8 have a configuration defined in the present application. In particular, the endless belt is made of a copolymer in which the polyamideimide resin constituting the base layer includes (c) a polymerized unit of a hindered phenol antioxidant. Therefore, the endless belt is made of the polyamideimide resin at the time of synthesizing the polyamideimide resin in the production thereof, and at the time of forming the base layer for forming the base layer by heat-treating the base layer forming coating liquid containing the synthesized polyamideimide resin. Thermal deterioration is suppressed and heat resistance is improved. For this reason, the endless belt can further improve the durability of the base layer as compared with the conventional endless belt. This is because the component (c) is dispersed and arranged in the polyamideimide resin at the molecular level, so that the effect of improving the heat resistance is increased, the thermal deterioration is effectively suppressed, and the durability of the base layer is further improved. Conceivable. Further, the endless belt has an advantage that the antioxidant is incorporated as a polymerization unit in the molecule of the polyamide-imide resin, so that the counterpart member is hardly contaminated with the antioxidant.

  Further, when the endless belts of Samples 1 to 8 are compared, the following can be understood. According to the results of the endless belts of Samples 3 to 5, a polydimethylsiloxane compound was added during the synthesis of the polyamideimide resin, and polymerized units based on the polydimethylsiloxane compound were introduced into the synthesized polyamideimide resin. MIT durability is improved by adding a polymer at both ends of the carboxylic acid during the synthesis of the resin, and introducing polymerized units based on the polymer components at both ends of the carboxylic acid into the synthesized polyamideimide resin, further improving the durability of the base layer It can be seen that it is easier to plan. Further, according to the result of the endless belt of Sample 2, even when a phosphorus antioxidant is used in combination with a hindered phenol antioxidant as the component (c), the MIT durability is improved and the base layer is improved. It can be seen that it is easier to further improve the durability.

  Note that the endless belt of Sample 8 has a larger amount of hindered phenol antioxidant than the endless belts of Sample 1 to Sample 7, so that the hindered phenol antioxidant polymerization unit in the polyamideimide resin is increased. The mol% of is increasing. Therefore, it is considered that the endless belt of the sample 8 has bonds other than the amide bond and the imide bond, and the durability is slightly lowered as compared with the endless belts of the samples 1 to 7.

  In addition, according to the method for producing an endless belt, it is possible to produce an endless belt having a base layer in which heat deterioration of the polyamide-imide resin is suppressed and heat resistance is improved, and durability is further improved as compared with the related art. I can say that.

  In addition, the endless belt manufacturing method does not mainly improve the durability by dispersing the silicone polymer. Therefore, the durability does not deteriorate due to the deterioration of the dispersibility, and the highly difficult dispersion control is unnecessary. It can be said that it is possible. Further, the endless belt manufacturing method is advantageous for manufacturing an endless belt in which the counterpart member is hardly contaminated with the antioxidant since the antioxidant is not added after the synthesis of the polyamideimide resin.

  As mentioned above, although the Example of this invention was described in detail, this invention is not limited to the said Example, A various change is possible within the range which does not impair the meaning of this invention.

  For example, in the above experimental example, a hindered phenol-based antioxidant was used as the component (c), but even when a hindered amine-based antioxidant is used, the effect of further improving durability is expected as described above. In addition, even when an appropriate amount of a polydimethylsiloxane compound is dispersed and mixed after the synthesis of the polyamideimide resin having the above structure, it is expected that the MIT durability is improved and the durability of the base layer is further improved.

1 Endless belt 2 Base layer

Claims (8)

An endless belt having at least a base layer formed in a cylindrical shape,
The endless belt is characterized in that the base layer is composed of a polyamide-imide resin made of a copolymer containing polymerized units of the following components (a) to (c).
(A) aromatic isocyanate compound (b) aromatic polyhydric carboxylic acid anhydride (c) hindered phenolic antioxidant and / or hindered amine antioxidant   2. The polyamideimide resin further comprises (d) the copolymer including a polymer unit of a polydimethylsiloxane compound, and / or (d) a polydimethylsiloxane compound. Endless belt as described in.   3. The endless belt according to claim 1, wherein the polyamide-imide resin further comprises (e) the copolymer including a polymerized unit of a carboxylic acid both terminal polymer.   The endless belt according to any one of claims 1 to 3, wherein the component (c) further contains a phosphorus-based antioxidant.   The endless polymer according to any one of claims 1 to 4, wherein the polymerized units of the component (c) in the polyamide-imide resin are in the range of 0.0005 mol% to 2.5 mol%. belt.   The endless belt according to claim 1, wherein the endless belt is used in an electrophotographic image forming apparatus. The following components (a) to (c) are heated and reacted in an organic solvent to synthesize a polyamideimide resin comprising a copolymer containing each polymer unit of the components (a) to (c), and the polyamideimide resin And a coating liquid preparation step of preparing a base layer forming coating liquid containing the organic solvent, and
A base layer forming step of forming a cylindrical base layer by applying the base layer forming coating liquid to the outer peripheral surface of a cylindrical or columnar mold, and then heat-treating the coating liquid,
A process for producing an endless belt, comprising:
(A) aromatic isocyanate compound (b) aromatic polyhydric carboxylic acid anhydride (c) hindered phenolic antioxidant and / or hindered amine antioxidant   The method for producing an endless belt according to claim 7, wherein the organic solvent is a nitrogen-containing organic solvent containing N.

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