Endless belt for electronic photograph apparatus

Abstract

To provide an endless belt for an electronic photograph apparatus which attains a physical property and fire-resistance at one time and can take environmental load into consideration at low cost.SOLUTION: In an endless belt 10 for an electronic photograph apparatus, a base layer 12 is formed from a resin composition including a polyamide-imide resin having structural units derived from the following components (A) to (C) and a flame retardant. The molar ratio of a structural unit (α) derived from the component (A) to a structural unit (β) derived from the component (B) is within the range of (α) / (β)=95 / 5 to 30 / 70, and the flame retardant is an organophosphorus compound. (A) diphenylmethane diisocyanate (MDI): (B) tolidine diisocyanate (TODI); (C) an anhydride of an aromatic polycarboxylic acid.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an endless belt for electrophotographic equipment, and more particularly to an endless belt for electrophotographic equipment used as a conveyor belt, intermediate transfer belt, etc. in electrophotographic equipment employing electrophotographic technology, such as a full-color LBP (laser beam printer) or a full-color MFP (multifunction printer). [Background technology]

[0002] 2. Description of the Related Art Known endless belts, such as transport belts and intermediate transfer belts for electrophotographic devices, include those having a base layer made of a fluorine-based resin, a polyimide resin, or a polyamide-imide resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-047587 A Summary of the Invention [Problem to be solved by the invention]

[0004] Fluorine resin endless belts can ensure flame retardancy, but they have a low elastic modulus and are expensive materials. In addition, there is also the issue of environmental impact. Polyimide resin endless belts can ensure flame retardancy and have a high elastic modulus, but the materials are expensive, and production requires a long time at high temperatures, making them less productive and cost-effective. Polyamide-imide resin endless belts can easily ensure a high elastic modulus, are less expensive than polyimide resin, and can be produced at low temperatures and in a short time, making them cost-effective. However, it is difficult to ensure flame retardancy with the material alone, and a flame retardant must be added, making it difficult to achieve both physical properties and flame retardancy.

[0005] An object of the present invention is to provide an endless belt for electrophotographic equipment which has both physical properties and flame retardancy, is low-cost, and is environmentally friendly. [Means for solving the problem]

[0006] In order to solve the above problems, the endless belt for electrophotographic equipment according to the present invention is an endless belt for electrophotographic equipment having at least a base layer, the base layer being formed using a resin composition containing a polyamide-imide resin having structural units derived from the following (A) to (C) and a flame retardant, the molar ratio of the structural unit (α) derived from (A) to the structural unit (β) derived from (B) being within the range of (α) / (β)=95 / 5 to 30 / 70, and the flame retardant being an organic phosphorus compound. (A) Diphenylmethane diisocyanate (MDI) (B) Tolidine diisocyanate (TODI) (C) Anhydrides of aromatic polycarboxylic acids

[0007] The organic phosphorus compound may be an organic phosphorus compound having a molecular weight of 350 or more. The anhydride of the aromatic polycarboxylic acid (C) may be trimellitic anhydride. The organic phosphorus compound may be a phosphoric acid ester. The content of the organic phosphorus compound may be 1.0 part by mass or more and 10 parts by mass or less relative to 100 parts by mass of the polyamideimide resin.

[0008] (1) An endless belt for electrophotographic equipment according to the present invention is an endless belt for electrophotographic equipment including at least a base layer, the base layer being formed using a resin composition containing a polyamide-imide resin having structural units derived from the following (A) to (C) and a flame retardant, the molar ratio of the structural unit (α) derived from (A) to the structural unit (β) derived from (B) being within the range of (α) / (β)=95 / 5 to 30 / 70, and the flame retardant being an organic phosphorus compound: (A) Diphenylmethane diisocyanate (MDI) (B) Tolidine diisocyanate (TODI) (C) Anhydrides of aromatic polycarboxylic acids

[0009] (2) In the above (1), the organophosphorus compound may be an organophosphorus compound having a molecular weight of 350 or more.

[0010] (3) In the above (1) or (2), the anhydride of the aromatic polyvalent carboxylic acid of (C) may be trimellitic anhydride.

[0011] (4) In any one of the above (1) to (3), the organic phosphorus compound may be a phosphoric acid ester.

[0012] (5) In any one of the above (1) to (4), the content of the organic phosphorus compound may be 1.0 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polyamideimide resin. Effect of the Invention

[0013] According to the endless belt for electrophotographic equipment of the present invention, the base layer is formed using a resin composition containing a polyamideimide resin having structural units derived from the above (A) to (C) and a flame retardant, the molar ratio of the structural unit (α) derived from the (A) to the structural unit (β) derived from the (B) is in the range of (α) / (β)=95 / 5 to 30 / 70, and the flame retardant is an organic phosphorus compound, so that both physical properties and flame retardancy are achieved, and the belt can be produced at low cost and with consideration given to environmental load.

[0014] When the organophosphorus compound has a molecular weight of 350 or more, it is less likely to bleed onto the base layer surface, and slippage of the endless belt due to a decrease in the friction coefficient is easily suppressed.

[0015] When the anhydride of aromatic polyvalent carboxylic acid of (C) is trimellitic anhydride, the reactivity with (A) and (B) is high, and the production can be performed at a low temperature in a short time, which is advantageous in terms of cost.

[0016] When the organic phosphorus compound is a phosphoric acid ester, it is possible to exhibit excellent flame retardant effect even with a small amount of addition, so that deterioration of physical properties is easily suppressed.In addition, since the toxicity is low, more consideration can be given to the environmental load.

[0017] When the content of the organophosphorus compound is 1.0 part by mass or more and 10 parts by mass or less relative to 100 parts by mass of the polyamideimide resin, even a small amount of the compound can provide an excellent flame retardant effect and deterioration of physical properties can be further suppressed. [Brief description of the drawings]

[0018] [Figure 1] 1 is a perspective view showing an outline of an endless belt for electrophotographic equipment according to one embodiment of the present invention; [Diagram 2] 2 is a cross-sectional view of the endless belt for electrophotographic equipment shown in FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] An endless belt for electrophotographic equipment (hereinafter, sometimes simply referred to as an endless belt) according to the present invention will be described in detail.

[0020] Fig. 1 shows an endless belt according to one embodiment of the present invention, and Fig. 2 shows a cross-sectional view of the endless belt shown in Fig. 1.

[0021] The endless belt 10 has a cylindrical base layer 12 and a surface layer 14 formed on the outer peripheral surface of the base layer 12 .

[0022] The base layer 12 serves as a base material for the endless belt 10. The base layer 12 is formed in a cylindrical shape and has a seamless structure with no seams in the circumferential direction.

[0023] The base layer 12 is formed using a resin composition containing a polyamideimide resin (PAI) having structural units derived from the following (A) to (C) and a flame retardant. (A) Diphenylmethane diisocyanate (MDI) (B) Tolidine diisocyanate (TODI) (C) Anhydrides of aromatic polycarboxylic acids

[0024] Examples of the diphenylmethane diisocyanate (MDI) of (A) include 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, polymeric MDI, etc. These may be used alone or in combination of two or more.

[0025] The molar ratio of the structural unit (α) derived from MDI to the structural unit (β) derived from TODI must be set within the range of (α) / (β)=95 / 5 to 30 / 70. It is preferably within the range of (α) / (β)=80 / 20 to 35 / 65, more preferably (α) / (β)=70 / 30 to 40 / 60. If the molar ratio of the structural unit (α) exceeds 95 (the molar ratio of the structural unit (β) is less than 5), the tensile modulus is low and the creep property is poor. In addition, it takes a long time to manufacture, the productivity is poor, and it is disadvantageous in terms of cost. And, if the molar ratio of the structural unit (α) is less than 30 (the molar ratio of the structural unit (β) exceeds 30), cracks are easily generated and the folding resistance (crack resistance) is deteriorated.

[0026] For (C), an anhydride of an aromatic polycarboxylic acid is used. If an aromatic polycarboxylic acid is used instead of an acid anhydride, the number of amide bonds increases, the elastic modulus decreases, and dimensional changes occur due to water absorption. In addition, the synthesis time increases, which is also disadvantageous in terms of cost. If an anhydride of an aliphatic polycarboxylic acid is used instead of an aromatic one, the elastic modulus decreases.

[0027] The anhydride of aromatic polyvalent carboxylic acid (C) is not particularly limited as long as it undergoes a condensation reaction with the above MDI and TODI and has an aromatic ring. For example, in addition to anhydrides of trimellitic acid and naphthalene-1,2,4-tricarboxylic acid, there are also anhydrides of benzene-1,2,4,5-tetracarboxylic acid (pyromellitic acid), benzophenone-3,3',4,4'-tetracarboxylic acid, diphenyl ether-3,3',4,4'-tetracarboxylic acid, benzene-1,2,3,4 -Tetracarboxylic acid, biphenyl-3,3',4,4'-tetracarboxylic acid, biphenyl-2,2',3,3'-tetracarboxylic acid, naphthalene-2,3,6,7-tetracarboxylic acid, naphthalene-1,2,4,5-tetracarboxylic acid, naphthalene-1,4,5,8-tetracarboxylic acid, decahydronaphthalene-1,4,5,8-tetracarboxylic acid, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic acid , 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic acid, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic acid, phenanthrene-1,3,9,10-tetracarboxylic acid, perylene-3,4,9,10-tetracarboxylic acid, bis(2,3-dicarboxyphenyl)methane, bis(3,4-dicarboxyphenyl)methane, 1,1-bis(2,3-di Examples of the dianhydrides include dianhydrides such as 1,1-bis(3,4-dicarboxyphenyl)ethane, 1,1-bis(3,4-dicarboxyphenyl)ethane, 2,2-bis(2,3-dicarboxyphenyl)propane, 2,3-bis(3,4-dicarboxyphenyl)propane, bis(3,4-dicarboxyphenyl)sulfone, bis(3,4-dicarboxyphenyl)ether, ethylene glycol bis(anhydrotrimellitate), and propylene glycol bis(anhydrotrimellitate). These are used alone or in combination of two or more. Among these, the anhydride of trimellitic acid (trimellitic anhydride) is preferably used from the viewpoints of reactivity, cost, solubility, etc.

[0028] The polyamideimide resin preferably has a number average molecular weight (Mn) in the range of 10,000 to 50,000, and particularly preferably has an Mn in the range of 15,000 to 40,000. If the Mn of the polyamideimide resin is less than 10,000, the tear strength is low and durability is deteriorated, whereas if the Mn of the polyamideimide resin exceeds 50,000, the solution viscosity is high and processability tends to be deteriorated.

[0029] For example, the polyamideimide resin can be prepared as follows: That is, a reaction vessel equipped with a stirrer, a nitrogen inlet pipe, a thermometer, and a cooling pipe is prepared, MDI and TODI are mixed so as to obtain the above-mentioned predetermined molar ratio, and a predetermined amount of an acid component such as trimellitic anhydride is mixed, and a polar solvent such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), γ-butyrolactone, etc. are charged, and the mixture is heated to a predetermined temperature (preferably 130° C.) over a predetermined time (preferably 1 hour) while stirring under a nitrogen stream, and the reaction is carried out at the predetermined temperature (preferably 130° C.) for a predetermined time (preferably about 5 hours), and then the reaction is stopped, whereby a solvent for the polyamideimide resin can be prepared.

[0030] The flame retardant used together with the polyamide-imide resin is preferably an organic phosphorus compound. Since the organic phosphorus compound can exhibit excellent flame retardant effect even when added in small amounts, the occurrence of cracks and bending resistance (crack resistance) caused by the addition of a large amount are suppressed, and the deterioration of physical properties is easily suppressed. In addition, since the toxicity is low, the environmental load can be considered. The organic phosphorus compound having a large molecular weight is more preferable because it is less likely to bleed onto the surface of the base layer 12. The molecular weight of the organic phosphorus compound is preferably 350 or more. More preferably, it is 360 or more, and even more preferably, it is 370 or more. The upper limit of the molecular weight of the organic phosphorus compound is not particularly limited, but is preferably 1000 or less from the viewpoint of compatibility with the polyamide-imide resin, solvent solubility, etc. More preferably, it is 750 or less, and even more preferably, it is 500 or less.

[0031] Examples of the organic phosphorus compound include phosphoric acid esters and phosphazene compounds. Among these, phosphoric acid esters and phosphazene compounds are more preferred from the viewpoints of compatibility with polyamide-imide resins, versatility, and supplyability. Furthermore, phosphoric acid esters are particularly preferred from the viewpoints of being able to exhibit excellent flame retardant effects with a small amount of addition and being low in toxicity.

[0032] Examples of the phosphate ester include aromatic phosphate ester and condensed phosphate ester. As the phosphate ester, aromatic phosphate ester is preferable from the viewpoint of high flame retardant effect. Examples of the aromatic phosphate ester include phosphate ester having one or more aryl groups. From the viewpoint of flame retardant effect, aromatic phosphate ester having each ester group having an aryl group (having three aryl groups) is more preferable. The aryl groups of a phosphate ester having multiple aryl groups may be the same aryl group or may be one or more different aryl groups.

[0033] Examples of aromatic phosphate esters include triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, tris-(isopropylphenyl)phosphate, tris-(tert-butylphenyl)phosphate, cresyl diphenyl phosphate, cresyl dixylenyl phosphate, tert-butylphenyl diphenyl phosphate, bis-(tert-butylphenyl)phenyl phosphate, isopropylphenyl diphenyl phosphate, bis-(isopropylphenyl)diphenyl phosphate, 2-ethylhexyl diphenyl phosphate, etc. Among these, tricresyl phosphate and cresyl dixylenyl phosphate are more preferable from the viewpoint of being less likely to bleed onto the surface of the base layer 12.

[0034] Condensed phosphate esters include resorcinol bis-diphenyl phosphate, resorcinol bis-dixylenyl phosphate, bisphenol A bis-diphenyl phosphate, biphenyl bis-diphenyl phosphate, and the like.

[0035] Examples of the phosphazene compound include cyclic and / or linear C1-6 alkyl C6-20 aryloxyphosphazenes such as phenoxyphosphazene, (poly)tolyloxyphosphazene (e.g., o-tolyloxyphosphazene, m-tolyloxyphosphazene, p-tolyloxyphosphazene, o,m-tolyloxyphosphazene, o,p-tolyloxyphosphazene, m,p-tolyloxyphosphazene, o,m,p-tolyloxyphosphazene, etc.), and (poly)xylyloxyphosphazene; and (poly)phenoxytolyloxyphosphazene (e.g., phenoxyo Examples of the cyclic and / or linear C6-20 aryl, C1-10 alkyl, C6-20 aryloxyphosphazenes include phenoxy m-tolyloxyphosphazene, phenoxy p-tolyloxyphosphazene, phenoxy o,m-tolyloxyphosphazene, phenoxy o,p-tolyloxyphosphazene, phenoxy m,p-tolyloxyphosphazene, phenoxy o,m,p-tolyloxyphosphazene, (poly)phenoxyxylyloxyphosphazene, (poly)phenoxytolyloxyxylyloxyphosphazene, and the like.

[0036] Among these, preferred are cyclic and / or linear phenoxyphosphazenes, cyclic and / or linear C1-3 alkyl C6-20 aryloxyphosphazenes, C6-20 aryloxy C1-3 alkyl C6-20 aryloxyphosphazenes (e.g., cyclic and / or linear tolyloxyphosphazene, cyclic and / or linear phenoxytolylphenoxyphosphazene, etc.).

[0037] The content of the organic phosphorus compound as a flame retardant is preferably 1.0 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the polyamideimide resin. When the content is 1.0 parts by mass or more, an excellent flame retardant effect can be exhibited. From this viewpoint, the content is more preferably 2.0 parts by mass or more, and even more preferably 2.5 parts by mass or more. On the other hand, when the content is 10 parts by mass or less, the amount of addition is suppressed to a small amount, and deterioration of physical properties is easily suppressed. From this viewpoint, the content is more preferably 7.0 parts by mass or less, and even more preferably 5.0 parts by mass or less.

[0038] The resin composition forming the base layer 12 may contain a conductive filler in addition to the polyamide-imide resin and the flame retardant.

[0039] Examples of conductive fillers include conductive carbon powders such as carbon black and graphite, metal powders such as aluminum powder and stainless steel powder, conductive metal oxides such as conductive zinc oxide (c-ZnO), conductive titanium oxide (c-TiO2), conductive iron oxide (c-Fe3O4), and conductive tin oxide (c-SnO2), and ionic conductive agents such as quaternary ammonium salts, sulfonates, aliphatic polyhydric alcohols, and aliphatic alcohol sulfate salts. These may be used alone or in combination of two or more.

[0040] The resin composition forming the base layer 12 may contain, in addition to the above-mentioned components, an organic solvent such as DMF, DMAC, toluene, acetone, or NMP, or a filler, if necessary.

[0041] The resin composition forming the base layer 12 can be prepared, for example, by appropriately blending polyamide-imide resin, flame retardant, organic solvent, and filler as necessary, mixing them with a stirring blade, and then dispersing them using a ring mill, ball mill, sand mill, or the like.

[0042] Next, the material for forming the surface layer 14 formed on the outer peripheral surface of the base layer 12 is not particularly limited, and examples thereof include silicone resins, fluorine resins, urethane resins, acrylic resins, polyamide resins, etc. These are used alone or in combination of two or more. Among these, liquid or solvent-soluble types are preferably used in consideration of normal workability. In addition, for the purpose of preventing dirt, improving coating film strength, or adhesion, the resin material may be modified, and examples thereof include modified acrylic resins. The modified acrylic resin is not particularly limited as long as it is based on the molecular structure of acrylic resin and modified with other resins or resin components, but silicone modified acrylic resins are preferably used.

[0043] The silicone-modified acrylic resin may be, for example, a silicone-grafted acrylic resin. The silicone-grafted acrylic resin is not particularly limited as long as it is a resin in which a silicone resin is graft-polymerized to an acrylic resin (main chain). A specific example of the silicone-grafted acrylic resin is SYMAC US-350 manufactured by Toagosei Co., Ltd.

[0044] The surface layer material may be a material obtained by subjecting the resin material to resin crosslinking using a resin crosslinking agent such as an isocyanate resin, an amino resin, a phenol resin, or a xylene resin, or an ultraviolet-curing material obtained by mixing a photopolymerization initiator with a photosensitive monomer or polymer.

[0045] The surface layer material can be prepared by, for example, appropriately blending modified acrylic resin and organic solvent such as DMF, toluene, acetone, etc., and mixing with a stirring blade. In order to form each layer with precision, it is preferable to use different types of organic solvents for the materials forming adjacent layers. That is, it is preferable to use different types of organic solvents for the surface layer material and the base layer material.

[0046] The endless belt 10 can be produced, for example, as follows. First, a resin composition for forming the base layer 12 is spray-coated on the surface of a mold (cylindrical substrate). Then, the resin composition is dried at 150 to 300° C. for 3 to 6 hours to form the base layer 12 on the surface of the mold. Next, a surface layer material is coated on the surface of the base layer 12 by a dipping method and dried, and then, air is blown between the base layer 12 and the cylindrical substrate, and the cylindrical substrate is removed. Thus, the endless belt 10 having a two-layer structure in which the surface layer 14 is formed on the surface of the base layer 12 can be produced. The method for forming the surface layer 14 is not limited to the above dipping method, and the surface layer 14 may be formed by spray coating, similar to the method for forming the base layer 12.

[0047] The base layer 12 of the endless belt 10 can be produced by the above-mentioned manufacturing method, as well as by an extrusion molding method, an inflation method, a blow molding method, a dipping method, a centrifugal molding method, etc. By omitting the formation of the surface layer 14, an endless belt having a single-layer structure consisting of only the base layer 12 can be produced.

[0048] The thickness of each layer of the endless belt 10 is appropriately set depending on the application of the belt, but the thickness of the base layer 12 is usually within a range of 30 to 300 μm, and preferably within a range of 50 to 200 μm. The thickness of the surface layer 14 is preferably within a range of 0.1 to 10 μm, and particularly preferably within a range of 0.5 to 5 μm. The endless belt 10 preferably has an inner peripheral length of 90 to 1500 mm and a width of about 100 to 500 mm. In other words, if the dimensions are set within the above ranges, the size becomes appropriate for use in an electrophotographic copying machine or the like.

[0049] According to the endless belt 10 having the above configuration, the base layer 12 is formed using a resin composition containing a polyamide-imide resin having structural units derived from the above (A) to (C) and a flame retardant, the molar ratio of the structural unit (α) derived from (A) to the structural unit (β) derived from (B) being in the range of (α) / (β)=95 / 5 to 30 / 70, and the flame retardant being an organic phosphorus compound, thereby achieving both physical properties and flame retardancy, and achieving low cost and environmental friendliness.

[0050] The endless belt for electrophotographic equipment of the present invention may have a structure including at least a base layer, and is not limited to a two-layer structure in which a surface layer 14 is directly formed on the outer peripheral surface of a base layer 12 as shown in Fig. 1. The endless belt for electrophotographic equipment of the present invention may have, for example, a single-layer structure consisting of only a base layer, a three-layer structure in which a thermoplastic resin layer or a rubber elastic layer is interposed between the base layer and the surface layer, or a four-layer structure in which both a thermoplastic resin layer and a rubber elastic layer are interposed between the base layer and the surface layer.

[0051] The material for the thermoplastic resin layer interposed between the base layer and the surface layer is not particularly limited, but a solvent such as methyl ethyl ketone (MEK), toluene, etc. is used together with the thermoplastic resin as necessary. The conductive filler as mentioned above may also be mixed into the material for the thermoplastic resin layer.

[0052] The thermoplastic resin is not particularly limited, and examples thereof include fluorine-based resins such as polyvinylidene fluoride (PVDF), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and ethylene-tetrafluoroethylene copolymer (ETFE), polyethylene resins, polystyrene resins, acrylic resins, polycarbonate (PC) resins, polyamide resins, EVA (ethylene-vinyl acetate copolymer) resins, and EEA (ethylene-ethyl acrylate copolymer) resins. These are used alone or in combination of two or more. Among these, it is preferable to use fluorine-based resins such as PVDF because of their excellent flame retardancy.

[0053] The material for the rubber elastic layer interposed between the base layer and the surface layer includes a rubber material, a vulcanizing agent, and, if necessary, a vulcanization accelerator, a solvent, a processing aid, an anti-aging agent, etc. The material for the rubber elastic layer may also contain the conductive filler as described above.

[0054] The rubber material is not particularly limited, but from the viewpoint of flame retardancy, chlorinated polyethylene rubber (CPE), chloroprene rubber (CR), etc. are used. Among these, the most suitable material is selected according to the electrical properties, elasticity, and durability required for each intermediate transfer belt.

[0055] The endless belt for electrophotographic equipment of the present invention is suitably used for applications such as toner image transfer, paper transfer and transport, and photoreceptor substrate in electrophotographic equipment employing electrophotographic technology, such as full-color LBPs (laser beam printers) and full-color MFPs (multifunction printers); however, the applications are not limited thereto, and the belt can also be used, for example, as a transfer belt for monochromatic electrophotographic copying machines that are not full-color. EXAMPLES

[0056] The present invention will be described in detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0057] Example 1 <Preparation of base layer forming material> A reaction vessel equipped with a stirrer, nitrogen inlet tube, thermometer, and cooling tube was charged with 54.0 parts by mass of MDI, 3.0 parts by mass of TODI, 43.0 parts by mass of trimellitic anhydride, and 280 parts by mass of NMP solvent, and the mixture was heated to 130°C over 1 hour with stirring under a nitrogen stream. The mixture was reacted at 130°C for about 5 hours, and then the reaction was stopped to prepare a PAI-NMP solution. The prepared PAI-NMP solution was mixed with a flame retardant <1> 3.0 parts by mass of the above and 5 parts by mass of conductive carbon were blended and mixed with a stirring blade, and then dispersed in a ball mill to prepare a material for forming a base layer.

[0058] <Making endless belts> A mold (cylindrical substrate) was prepared, and the surface of the mold was spray-coated with a base layer forming material to form a base layer on the surface of the mold, followed by heat treatment for 2 hours at 250° C. Next, air was blown between the base layer and the cylindrical substrate to remove the cylindrical substrate, thereby producing an endless belt with a single layer structure and a thickness of 80 μm.

[0059] (Examples 2 to 5) An endless belt was produced in the same manner as in Example 1, except that in the preparation of the base layer forming material, the blending ratio (parts by mass) shown in the table was used.

[0060] Comparative Example 1 <Preparation of base layer forming material> A base layer forming material was prepared by kneading 100 parts by mass of PVdF (Neoflon VT-100, manufactured by Daikin Industries), 36 parts by mass of the conductive agent c-TiO2 (Titanium Black 13M, manufactured by Mitsubishi Materials), and 400 parts by mass of acetone in a ball mill and then stirring.

[0061] <Making endless belts> An endless belt was produced in the same manner as in Example 1.

[0062] Comparative Example 2 <Preparation of base layer forming material> In a reaction vessel equipped with a stirrer, nitrogen inlet tube, thermometer, and cooling tube, 44 parts by mass of 4,4'-biphthalic anhydride (BPDA), 40 parts by mass of 4,4'-diaminodiphenyl ether (ODA), and 200 parts by mass of NMP solvent were charged, and the mixture was reacted for about 3 hours at room temperature (25°C) or lower while stirring under a nitrogen stream, and then the reaction was stopped to prepare a polyamic acid-NMP solution (solid concentration: 26% by weight), which is a precursor of PI. Five parts by mass of conductive carbon was added to the prepared polyamic acid-NMP solution, mixed with a stirring blade, and then dispersed in a ball mill to prepare a base layer forming material.

[0063] <Making endless belts> An endless belt was produced in the same manner as in Example 1.

[0064] (Comparative Examples 3 to 5) An endless belt was produced in the same manner as in Example 1, except that in the preparation of the base layer forming material, the MDI / TODI ratio was changed to the blending ratio (parts by mass) shown in the table.

[0065] (Comparative Examples 6 to 8) An endless belt was produced in the same manner as in Example 1, except that in the preparation of the base layer forming material, the flame retardant was changed and the blending ratio (parts by mass) was set as shown in the table.

[0066] The materials used are as follows: MDI: "Millionate MT" made by Nippon Polyurethane, Mn: 250.26 TODI: Nippon Soda "TODI / R203", Mn: 264.29 Trimellitic anhydride: Aromatic polycarboxylic acid anhydride, Mn: 192.12 4,4'-Biphthalic anhydride (BPDA) 4,4'-Diaminodiphenyl ether (ODA) Conductive carbon: Lion Specialty Chemicals' Ketjenblack EC300J Flame retardants <1> : Tricresyl phosphate (molecular weight: 368), "TCP" manufactured by Daihachi Chemical Industry Co., Ltd. Flame retardants <2> : Cresyl di-2,6-xylenyl phosphate (molecular weight: 396), "PX110" manufactured by Daihachi Chemical Industry Flame retardants <3> : Triphenyl phosphate (molecular weight: 326), "TPP" manufactured by Daihachi Chemical Industry Co., Ltd. Flame retardants <4> : Cresyl diphenyl phosphate (molecular weight: 340), "CDP" manufactured by Daihachi Chemical Industry Co., Ltd. Flame retardants <5> : Polybrominated biphenyls Flame retardants <6> : Polychlorinated biphenyls Flame retardants <7> : Aluminum hydroxide, Sumitomo Chemical's "Aluminum Hydroxide C-305"

[0067] The endless belt thus produced was used to evaluate the various properties according to the following criteria.

[0068] <Tensile modulus> The tensile modulus was measured according to JIS K7127. The pulling speed was 10±2.0 mm per minute. A tensile modulus of 3 GPa or more was marked as "good," and a tensile modulus of less than 3 GPa was marked as "poor."

[0069] <Break resistance (MIT value)> In accordance with JIS P8115, the MIT number of each endless belt was measured under a load of 9.8 N using a Folding Endurancetester MIT-D (manufactured by Toyo Seiki Co., Ltd.). The MIT number is an index for evaluating folding resistance, and the higher the MIT number, the better the folding resistance. An MIT number of 5K times (5000 times) or more was marked as "◯", and an MIT number of less than 5K times (5000 times) was marked as "X".

[0070] <Flame retardancy> Using the base layer material of each endless belt, a flame retardancy evaluation test was conducted in accordance with UL-94. The flame retardancy evaluation indicates that "VTM-0" is more flame retardant than "VTM-1." VTM-0 is rated as "Good," VTM-1 as "Good," and VTM-2 and below as "Poor."

[0071] <Environmental load> Items regulated by Rohs REACH (including substances of very high concern) are marked with an "X" and items not regulated are marked with an "O".

[0072] <Material synthesis time> The synthesis times of polyamideimide or polyimide were compared. Synthesis times of 15 hours or less were marked as "good", and those over 15 hours were marked as "bad".

[0073] <Price> In the synthesis of polyamide-imide, the cost when MDI / TODI=50 / 50 is set as 100, and the values ​​are expressed as relative values. 120 or less is marked as "Good", 120 to 150 is marked as "Good", and over 150 is marked as "Poor".

[0074] <Rate of spinning> Using a commercially available MFP unit (RICOH's IMC6000), we measured the rate at which the belt ran idle for 1 mm or more during initial drive. We performed a total of five measurements on five samples.

[0075] [Table 1]

[0076] In Comparative Example 1, the base layer of the endless belt is made of fluororesin. In Comparative Example 1, flame retardancy can be ensured, but the elastic modulus is low and the material is expensive. Furthermore, there is also the problem of environmental impact. In Comparative Example 2, the base layer of the endless belt is made of polyimide resin. In Comparative Example 2, flame retardancy can be ensured and the elastic modulus is high, but the material is expensive and requires a long time for production at high temperatures, resulting in poor productivity and being disadvantageous in terms of cost.

[0077] In Comparative Example 3, the base layer of the endless belt is made of polyamide-imide resin, but the isocyanate component is made of only MDI. Therefore, in Comparative Example 3, the necessary elastic modulus cannot be ensured. In addition, the synthesis time for polyamide-imide synthesis is long, which is disadvantageous in terms of cost. In Comparative Examples 4 and 5, the base layer of the endless belt is made of polyamide-imide resin, but the amount of MDI in the isocyanate component is insufficient. Therefore, in Comparative Examples 4 and 5, the folding resistance (MIT number of times) is poor.

[0078] In Comparative Examples 6 and 7, a halogen compound is used as a flame retardant in the base layer of the endless belt. Comparative Examples 6 and 7 have a problem in terms of environmental impact. Comparative Example 8 uses aluminum hydroxide as a flame retardant in the base layer of the endless belt. Metal hydrate flame retardants have a low flame retardant effect, so a large amount needs to be added to ensure the required flame retardancy. In Comparative Example 8, the addition of a large amount of flame retardant results in poor breakage resistance (MIT number of times).

[0079] In Examples 1 to 5, the base layer of the endless belt is made of a polyamide-imide resin, and the MDI / TODI ratio of the isocyanate component is within a specific range. In addition, an organic phosphorus compound is used as a flame retardant. In Examples 1 to 5, the required elastic modulus is ensured, and there are no problems with breakage resistance. Furthermore, the synthesis time for polyamide-imide conversion is short, and there are no problems in terms of cost. Furthermore, the environmental load is taken into consideration. Furthermore, the flame retardancy is excellent. Therefore, according to the Examples, it is clear that both physical properties and flame retardancy are achieved, and environmental load is taken into consideration at low cost.

[0080] Comparison between the working examples reveals that the larger the molecular weight of the organophosphorus compound used as the flame retardant, the less likely the flame retardant is to bleed onto the belt surface, and the easier it is to prevent the drive from running idle due to a decrease in the friction coefficient.

[0081] Although the embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the present invention. [Explanation of symbols]

[0082] 10 Endless belt 12 Base layer 14 Surface layer

Claims

1. An endless belt for an electrophotographic device comprising at least a base layer, The base layer is formed using a resin composition containing a polyamideimide resin having structural units derived from the following (A) to (C) and a flame retardant, the molar ratio of the structural unit (α) derived from (A) to the structural unit (β) derived from (B) is within the range of (α) / (β)=95 / 5 to 30 / 70; The endless belt for electrophotographic equipment, wherein the flame retardant is an organic phosphorus compound. (A) Diphenylmethane diisocyanate (MDI) (B) Tolidine diisocyanate (TODI) (C) Anhydrides of aromatic polycarboxylic acids

2. 2. The endless belt for electrophotographic equipment according to claim 1, wherein said organic phosphorus compound has a molecular weight of 350 or more.

3. 3. The endless belt for electrophotographic equipment according to claim 1, wherein the anhydride of the aromatic polyvalent carboxylic acid (C) is trimellitic anhydride.

4. 3. The endless belt for electrophotographic apparatus according to claim 1, wherein said organic phosphorus compound is a phosphoric acid ester.

5. 3. The endless belt for electrophotographic equipment according to claim 1, wherein the content of said organic phosphorus compound is from 1.0 part by mass to 10 parts by mass based on 100 parts by mass of said polyamide-imide resin.

6. the organophosphorus compound is an organophosphorus compound having a molecular weight of 350 or more, The aromatic polycarboxylic acid anhydride of the component (C) is trimellitic anhydride, the organophosphorus compound is a phosphoric acid ester, 2. The endless belt for electrophotographic equipment according to claim 1, wherein the content of said organic phosphorus compound is from 1.0 part by mass to 10 parts by mass based on 100 parts by mass of said polyamide-imide resin.

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