Endless belt for electro-photographic apparatus

Abstract

To provide an endless belt for an electro-photographic apparatus which has improved demoldability while maintaining a coefficient of friction.SOLUTION: An endless belt 10 for an electro-photographic apparatus has a base layer 12 formed using a modified polyamide-imide resin obtained by copolymerizing the following (A) to (C), and contains polyalkylene imine and polyoxyethylene alkyl ether. (A) An aromatic isocyanate compound, (B) anhydride of aromatic polyvalent carboxylic acid, and (C) silicone polymer having a polydimethylsiloxane structure in its molecule, and having a group reactive with the isocyanate group of the (A) at one terminal or both terminals.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] Known endless belts, such as conveyor belts and intermediate transfer belts for electrophotographic devices, include those having a base layer made of fluororesin or polyimide resin mixed with conductive carbon black, and also those having a base layer made of polyamide-imide resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-281670 A Summary of the Invention [Problem to be solved by the invention]

[0004] The base layer of the endless belt can be produced, for example, by coating a base layer forming material on a cylindrical mold and then removing the material from the mold. At this time, a release agent is applied to the surface of the mold or a release agent is added to the base layer forming material so that the base layer of the endless belt can be easily removed from the mold. The method of coating the mold surface with a release agent is disadvantageous in terms of cost due to the control process of coating, etc. The method of adding a release agent to the base layer material affects the physical properties of the base layer material, so selection is important.

[0005] An object of the present invention is to provide an endless belt for electrophotographic equipment which has improved releasability while maintaining a constant coefficient of friction. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides an endless belt for electrophotographic equipment, which is driven in a circumferential direction with its surface in contact with or in close proximity to a photoreceptor, and in which the base layer is formed using a modified polyamideimide resin obtained by copolymerizing the following (A) to (C), and which contains a polyalkyleneimine and a polyoxyethylene alkyl ether: (A) Aromatic isocyanate compound (B) Anhydrides of aromatic polycarboxylic acids (C) A silicone polymer having a polydimethylsiloxane structure in the molecule, the silicone polymer having a reactive group for the isocyanate group of (A) at one or both ends.

[0007] The polyalkyleneimine is preferably 0.2 to 20 parts by mass, and the polyoxyethylene alkyl ether is preferably 0.1 to 5 parts by mass, relative to 100 parts by mass of the modified polyamideimide resin. The silicone polymer (C) is preferably one having a total of two reactive groups, at least one of a hydroxyl group and a carboxyl group, at one end. The blending ratio of the silicone polymer (C) is preferably 1 to 20% by mass based on the total amount of the components (A) to (C). The carbon number of the alkylene of the polyalkyleneimine is preferably 2 to 4. The carbon number of the alkyl of the polyoxyethylene alkyl ether is preferably 8 to 16.

[0008] (1) The endless belt for electrophotographic equipment according to the present invention is an endless belt for electrophotographic equipment that is driven in a circumferential direction with its surface in contact with or in close proximity to a photoreceptor, and the base layer is formed using a modified polyamideimide resin obtained by copolymerizing the following (A) to (C), and contains a polyalkyleneimine and a polyoxyethylene alkyl ether: (A) Aromatic isocyanate compound (B) Anhydrides of aromatic polycarboxylic acids (C) A silicone polymer having a polydimethylsiloxane structure in the molecule, the silicone polymer having a reactive group for the isocyanate group of (A) at one or both ends.

[0009] (2) In the above (1), the content of the polyalkyleneimine may be from 0.2 to 20 parts by mass, and the content of the polyoxyethylene alkyl ether may be from 0.1 to 5 parts by mass, relative to 100 parts by mass of the modified polyamideimide resin.

[0010] (3) In the above (1) or (2), the silicone polymer (C) may have a total of two reactive groups, at least one of a hydroxyl group and a carboxyl group, at one end.

[0011] (4) In any one of the above (1) to (3), the blending ratio of the silicone polymer (C) may be 1% by mass or more and 20% by mass or less of the total amount of the (A) to (C).

[0012] (5) In any one of the above (1) to (4), the number of carbon atoms in the alkylene of the polyalkyleneimine may be 2 or more and 4 or less.

[0013] (6) In any one of the above (1) to (5), the number of carbon atoms in the alkyl of the polyoxyethylene alkyl ether may be 8 or more and 16 or less. Effect of the Invention

[0014] According to the endless belt for electrophotographic equipment of the present invention, the base layer is formed using a modified polyamideimide resin obtained by copolymerizing the above-mentioned (A) to (C), and contains a polyalkyleneimine and a polyoxyethylene alkyl ether. Therefore, it is possible to improve releasability while maintaining the friction coefficient.

[0015] When the amount of the polyalkyleneimine is 0.2 parts by mass or more and 20 parts by mass or less and the amount of the polyoxyethylene alkyl ether is 0.1 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the modified polyamideimide resin, it is possible to highly achieve both the effect of maintaining the friction coefficient and the effect of improving demoldability.

[0016] And, when the silicone polymer (C) has at least two reactive groups, either hydroxyl or carboxyl, at one end, the reactive group (hydroxyl or carboxyl) at one end of the silicone polymer reacts directly with the isocyanate group of the aromatic isocyanate compound, and the polydimethylsiloxane structure can be incorporated into the polyamide-imide resin in the form of a graft copolymer. Therefore, the polydimethylsiloxane structure is unevenly distributed on the surface side of the base layer during heat treatment, and the friction coefficient can be particularly reduced.

[0017] When the blending ratio of the silicone polymer (C) is 1% by mass or more and 20% by mass or less of the total amount of the components (A) to (C), the durability and elongation are excellent.

[0018] When the number of carbon atoms in the alkylene of the polyalkyleneimine is 2 or more and 4 or less, the effect of improving demoldability is excellent.

[0019] When the carbon number of the alkyl of the polyoxyethylene alkyl ether is 8 or more and 16 or less, the effect of improving demoldability is excellent. [Brief description of the drawings]

[0020] [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

[0021] 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.

[0022] 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.

[0023] 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 .

[0024] 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.

[0025] The base layer 12 is formed using a modified polyamideimide resin obtained by copolymerizing the following (A) to (C), and contains polyalkyleneimine and polyoxyethylene alkyl ether. (A) Aromatic isocyanate compound (B) Anhydrides of aromatic polycarboxylic acids (C) A silicone polymer having a polydimethylsiloxane structure in the molecule, the silicone polymer having a reactive group for the isocyanate group of (A) at one or both ends.

[0026] The aromatic isocyanate compound (A) is not particularly limited as long as it is an isocyanate compound having an aromatic ring in the molecule. Examples of the aromatic isocyanate compound (A) include diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), tolidine diisocyanate (TODI), xylylene diisocyanate (XDI), lysine diisocyanate (LDI), naphthalene diisocyanate (NDI), paraphenylene diisocyanate (PPDI), and tetramethylxylene diisocyanate (TMXDI). The aromatic isocyanate compound (A) may be used alone or in combination of two or more. Among these, MDI and TODI are preferred in terms of reactivity, cost, and solubility.

[0027] The aromatic polycarboxylic anhydride (B) is not particularly limited as long as it has an aromatic ring in the molecule and undergoes a condensation reaction with the aromatic isocyanate compound (A). Examples of the aromatic polycarboxylic anhydride (B) include aromatic polycarboxylic anhydrides (B1) and aromatic polycarboxylic dianhydrides (B2).

[0028] Examples of the aromatic polyvalent carboxylic acid anhydride (B1) include trimellitic anhydride, naphthalene-1,2,4-tricarboxylic anhydride, etc. Among these, trimellitic anhydride is preferred from the standpoints of reactivity, cost, solubility, etc.

[0029] Examples of the aromatic polycarboxylic dianhydride (B2) include benzene-1,2,4,5-tetracarboxylic 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, and biphenyl-2,2',3,3'-tetracarboxylic dianhydride. Water, naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, decahydronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic 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 Examples of suitable dianhydrides include 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride, 2,3-bis(3,4-dicarboxyphenyl)propane dianhydride, bis(3,4-dicarboxyphenyl)sulfone dianhydride, bis(3,4-dicarboxyphenyl)ether dianhydride, ethylene glycol bis(anhydrotrimellitate), propylene glycol bis(anhydrotrimellitate), etc. Among these, ethylene glycol bis(anhydrotrimellitate) is preferred from the standpoints of reactivity, cost, solubility, etc.

[0030] The aromatic polycarboxylic anhydride (B) may be one of B1 and B2, or two or more of them may be used in combination. An aromatic polycarboxylic acid may be used in combination with the aromatic polycarboxylic anhydride (B). The aromatic polycarboxylic anhydride (B) may be used in combination with B1 and B2. When B1 and B2 are used in combination, the ratio of imide groups in the modified polyamide-imide resin increases, so that the water absorption property decreases and the bending tendency of the endless belt 10 can be improved.

[0031] When B1 and B2 are used in combination, the molar mixing ratio of B1 to B2 is preferably within a range of B1 / B2=90 / 10 to 50 / 50, and more preferably within a range of B1 / B2=80 / 20 to 60 / 40. When the molar mixing ratio of B1 to B2 is within the above range, the bending tendency of the endless belt 10 can be improved while suppressing deterioration of the bending resistance.

[0032] The silicone polymer (C) is a silicone polymer having a polydimethylsiloxane structure in the molecule, and has a reactive group for the isocyanate group of (A) at one or both ends. The reactive group of the silicone polymer (C) reacts directly with the isocyanate group of the aromatic isocyanate compound (A), and the polydimethylsiloxane structure is incorporated into the polyamide-imide resin in the form of a block copolymer or graft copolymer. This can improve the flex resistance of the highly rigid polyamide-imide resin. In addition, the friction coefficient can be reduced because the polydimethylsiloxane structure is incorporated into the polyamide-imide resin.

[0033] Examples of the silicone polymer (C) include those having one reactive group at each end and those having two reactive groups at one end. Examples of the reactive group include hydroxyl groups, carboxyl groups, and amino groups. Examples of the silicone polymer having one reactive group at each end include carboxylic acid-terminated silicone polymers having one carboxyl group at each end (e.g., "BY16-750" manufactured by Toray Dow Corning Silicone). Examples of the silicone polymer having two reactive groups at one end include one-end bifunctional silicone polymers having two hydroxyl groups at one end (e.g., "X-22-176DX" manufactured by Shin-Etsu Chemical Co., Ltd.).

[0034] When the silicone polymer (C) has hydroxyl or carboxyl groups at both ends, the reactive groups (hydroxyl or carboxyl groups) at both ends of the silicone polymer (C) react directly with the isocyanate groups of the aromatic isocyanate compound (A), and the polydimethylsiloxane structure can be uniformly incorporated into the polyamide-imide resin in the form of a block copolymer, thereby improving flex resistance.

[0035] When the silicone polymer (C) has at least two reactive groups, either a hydroxyl group or a carboxyl group, at one end, the reactive group (hydroxyl group or carboxyl group) at one end of the silicone polymer (C) reacts directly with the isocyanate group of the aromatic isocyanate compound (A) to incorporate a polydimethylsiloxane structure into the polyamide-imide resin in the form of a graft copolymer. In this way, the polydimethylsiloxane structure becomes unevenly distributed on the surface side of the base layer 12 during heat treatment, and the friction coefficient in particular can be reduced.

[0036] The hydroxyl value or acid value of the silicone polymer (C) is preferably within the range of 1 to 1000 mgKOH / g, more preferably within the range of 4 to 150 mgKOH / g. The number average molecular weight (Mn) of the silicone polymer (C) is preferably within the range of 200 to 40,000, more preferably within the range of 1,000 to 20,000.

[0037] The blending ratio of the silicone polymer (C) is preferably 1% by mass or more and 20% by mass or less of the total amount of the above (A) to (C). More preferably, it is 2% by mass or more and 15% by mass or less. When the blending ratio of the silicone polymer (C) is 1% by mass or more, the durability of the endless belt 10 is excellent. Furthermore, when the blending ratio of the silicone polymer (C) is 20% by mass or less, the elongation of the endless belt 10 can be ensured.

[0038] The modified polyamideimide resin may be a copolymer of the above (A) to (C), or may be a copolymer of the above (A) to (C) and a carboxylic acid-terminated polymer (D). The carboxylic acid-terminated polymer (D) plays a role similar to a soft segment, imparting flexibility to the modified polyamideimide resin, increasing the breaking elongation of the endless belt 10, and improving durability.

[0039] The polymer (D) having carboxylic acid at both ends is not particularly limited as long as it has one carboxylic acid at each end of the polymer. Examples of the polymer (D) having carboxylic acid at both ends include polybutadiene having carboxylic acid at both ends, hydrogenated polybutadiene having carboxylic acid at both ends, polyester having carboxylic acid at both ends, polyamide having carboxylic acid at both ends, and polyacrylonitrile-butadiene copolymer having carboxylic acid at both ends. The modified polyamide-imide resin may contain only one of these polymers as the polymer (D) having carboxylic acid at both ends, or may contain two or more of them.

[0040] The polymer (D) having carboxylic acids at both ends is obtained by introducing carboxylic acids to both ends of a polymer by a known method. Examples of the carboxylic acids to be introduced include aliphatic carboxylic acids and aromatic carboxylic acids. Examples of the aliphatic carboxylic acids include adipic acid, sebacic acid, suberic acid, oxalic acid, succinic acid, suberic acid, azelaic acid, dodecanedicarboxylic acid, undecanedicarboxylic acid, maleic acid, fumaric acid, and itaconic acid. Examples of the aromatic carboxylic acids include terephthalic acid, isophthalic acid, phthalic acid, chlorophthalic acid, and nitrophthalic acid.

[0041] The acid value of the polymer (D) having carboxylic acid at both ends is preferably within a range of 15 to 150 mgKOH / g, more preferably within a range of 45 to 110 mgKOH / g. The number average molecular weight (Mn) of the polymer (D) having carboxylic acid at both ends is preferably within a range of 750 to 7500, more preferably within a range of 1000 to 2500.

[0042] The blending ratio of the polymer (D) having carboxylic acid at both ends is preferably within a range of 5 to 50% by mass of the total amount of the above (A) to (D), and more preferably within a range of 10 to 30% by mass. When the blending ratio of the polymer (D) having carboxylic acid at both ends is 5% by mass or more, durability can be ensured. When the blending ratio of the polymer (D) having carboxylic acid at both ends is 50% by mass or less, deterioration of the creep rate can be easily suppressed.

[0043] The molar mixing ratio of the total number of moles (a) of the isocyanate group of the aromatic isocyanate compound (A), the total number of moles (b) of the acid anhydride group and the carboxyl group of the anhydride of the aromatic polycarboxylic acid (B), and the total number of moles (d) of the carboxyl group of the carboxylic acid-terminated polymer (D) is preferably within the range of (a) / [(b)+(d)]=90 / 100 to 130 / 100. More preferably, it is within the range of (a) / [(b)+(d)]=100 / 100 to 120 / 100. When the value of (a) / [(b)+(d)] is in the suitable range, the molecular weight of the modified polyamideimide resin can be increased and durability can be ensured.

[0044] The modified polyamide-imide resin can be prepared as follows. A reaction vessel equipped with a stirrer, a nitrogen inlet tube, a thermometer, and a cooling tube is prepared, and a predetermined amount of an aromatic isocyanate compound (A), an aromatic polycarboxylic acid anhydride (B), a silicone polymer (C), and, if necessary, a carboxylic acid-terminated polymer (D) are mixed, and a polar solvent such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), and γ-butyrolactone is charged, and the temperature is raised to a predetermined temperature (preferably 130 to 150 ° C.) over a predetermined time (preferably 1 to 3 hours) while stirring under a nitrogen stream. Next, the reaction is carried out at a predetermined temperature (preferably 130 to 150 ° C.) for a predetermined time (preferably about 3 to 5 hours), and then the reaction is stopped, whereby a modified polyamide-imide resin can be prepared.

[0045] The modified polyamideimide resin preferably has a number average molecular weight (Mn) in the range of 5,000 to 100,000. More preferably, Mn is in the range of 10,000 to 50,000. When the number average molecular weight (Mn) of the modified polyamideimide resin is 5,000 or more, the resin has excellent tear strength and durability. When the number average molecular weight (Mn) of the modified polyamideimide resin is 100,000 or less, the solution viscosity is kept low and the resin has excellent processability. The number average molecular weight (Mn) can be measured by gel permeation chromatography (GPC).

[0046] The polyalkyleneimine is a resin having a polyalkyleneimine skeleton, and is obtained by polymerizing one or more alkyleneimines (e.g., ethyleneimine, propyleneimine) by a conventional method. The polyalkyleneimine may be a linear polyalkyleneimine having a linear polyalkyleneimine chain, or a branched polyalkyleneimine having a branched polyalkyleneimine chain.

[0047] The number of carbon atoms in the alkylene of the polyalkyleneimine is preferably from 2 to 4. More preferably, it is from 2 to 3. Specific examples of the polyalkyleneimine include polyethyleneimine, polypropyleneimine, and polybutyleneimine.

[0048] The number average molecular weight of the polyalkyleneimine is preferably from 300 to 30000. More preferably, it is from 600 to 10000. The number average molecular weight of the polyalkyleneimine is measured by GPC (gel permeation chromatography) using pullulan as a standard substance.

[0049] Polyoxyethylene alkyl ether is a compound represented by the following general formula (1). R-(O-CH 2 -CH 2 ) n -OH (1)

[0050] In formula (1), R is a linear or branched alkyl group, and n is the number of repeating units. The number of carbon atoms in R is preferably 8 to 16, and more preferably 10 to 14. n is preferably 5 to 20, and more preferably 7 to 15.

[0051] The base layer 12 contains polyalkyleneimine and polyoxyethylene alkyl ether in the modified polyamideimide resin, and thus the demoldability can be improved while maintaining the coefficient of friction. The above effect is sufficient when the modified polyamideimide resin contains polyalkyleneimine and polyoxyethylene alkyl ether in combination. The above effect is not sufficient when the modified polyamideimide resin contains only polyalkyleneimine or only polyoxyethylene alkyl ether. Polyalkyleneimine and polyoxyethylene alkyl ether are highly compatible with the modified polyamideimide resin, so there is little risk of the physical properties being reduced. There is also little risk of the coefficient of friction being reduced due to bleeding.

[0052] It is preferable that the amount of polyalkyleneimine is 0.2 to 20 parts by mass and the amount of polyoxyethylene alkyl ether is 0.1 to 5 parts by mass relative to 100 parts by mass of the modified polyamideimide resin, which makes it possible to highly simultaneously achieve the effect of maintaining the friction coefficient and the effect of improving demoldability.

[0053] From the viewpoint of improving demoldability, the content of polyalkyleneimine is preferably 0.2 parts by mass or more, more preferably 0.3 parts by mass or more, relative to 100 parts by mass of the modified polyamideimide resin. From the viewpoint of suppressing deterioration of the physical properties of the base layer 12, the content of polyalkyleneimine is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, relative to 100 parts by mass of the modified polyamideimide resin.

[0054] From the viewpoint of improving demoldability, the content of polyoxyethylene alkyl ether is preferably 0.1 parts by mass or more, more preferably 0.2 parts by mass or more, relative to 100 parts by mass of the modified polyamideimide resin. From the viewpoint of suppressing deterioration of the physical properties of the base layer 12, the content of polyoxyethylene alkyl ether is preferably 5 parts by mass or less, more preferably 3 parts by mass or less, relative to 100 parts by mass of the modified polyamideimide resin.

[0055] When the carbon number of the alkylene of the polyalkyleneimine is 2 or more and 4 or less, the effect of improving demoldability is excellent. When the carbon number of the alkyl of the polyoxyethylene alkyl ether is 8 or more and 16 or less, the effect of improving demoldability is excellent.

[0056] The base layer 12 may contain other components in addition to the modified polyamideimide resin, polyalkyleneimine, and polyoxyethylene alkyl ether, such as a conductive agent, a filler, and a phosphorus-containing polyester resin.

[0057] Examples of conductive agents 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, conductive titanium oxide, conductive iron oxide and conductive tin oxide, and ionic conductive agents such as quaternary ammonium salts, phosphate esters, sulfonates, aliphatic polyhydric alcohols and aliphatic alcohol sulfate salts.

[0058] The phosphorus-containing polyester resin serves as a flame retardant. The phosphorus-containing polyester resin preferably has a phosphorus content in the range of 3 to 15% by mass, more preferably in the range of 5 to 10% by mass.

[0059] The base layer forming material for forming the base layer 12 can be prepared by mixing modified polyamideimide resin, polyalkyleneimine, polyoxyethylene alkyl ether, and other components added as necessary. The base layer forming material may be diluted with an organic solvent to make it easier to apply. Examples of the organic solvent include DMF, DMAC, toluene, acetone, and NMP. The base layer forming material can be mixed with a stirring blade. After mixing, it is recommended to disperse the material using a ring mill, a ball mill, a sand mill, or the like.

[0060] The surface layer 14 can be formed using a surface layer forming material. Examples of the main components of the surface layer forming material include silicone resins, fluorine resins, urethane resins, acrylic resins, and polyamide resins. These may be used alone as the main components of the surface layer forming material, or two or more may be used in combination. In consideration of workability, liquid or solvent-soluble types are preferably used as the main components of the surface layer forming material. In addition, modified resins are preferable for the purpose of preventing dirt, improving coating strength, or adhesion. Examples of such modified resins include modified acrylic resins. Examples of modified acrylic resins include silicone modified acrylic resins. Examples of silicone modified acrylic resins include silicone grafted acrylic resins. Examples of silicone grafted acrylic resins include "Simac US-350" manufactured by Toagosei.

[0061] For the main component, a resin crosslinking agent such as an isocyanate resin, an amino resin, a phenol resin, a xylene resin, etc. may be used. Also, an ultraviolet-curing material may be used.

[0062] The surface layer forming material can be prepared by diluting the above-mentioned main components in an organic solvent such as DMF, toluene, or acetone and mixing with a stirring blade. In order to form each layer with high accuracy, it is preferable to use different types of organic solvents for the materials for forming adjacent layers. In other words, it is preferable to use different types of organic solvents for the material for forming the surface layer and the material for forming the base layer.

[0063] The base layer 12 of the endless belt 10 can be formed by spray-coating the surface of a mold (cylindrical substrate) with a material for forming the base layer, and drying the material at 150 to 300° C. for 3 to 6 hours. The surface layer 14 of the endless belt 10 can be formed by coating the surface of the base layer 12 on the mold with the material for forming the surface layer by a dipping method, and drying the material. Thereafter, the cylindrical substrate is removed by blowing air between the base layer 12 and the cylindrical substrate, and the two-layered endless belt 10 in which the surface layer 14 is formed on the surface of the base layer 12 can be produced.

[0064] The base layer 12 can also be formed by extrusion molding, inflation molding, blow molding, dipping, centrifugal molding, etc. The surface layer 14 can also be formed by spray coating, like the base layer 12.

[0065] The thickness of the base layer 12 is preferably within a range of 30 to 300 μm, and more 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 more 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.

[0066] In the endless belt 10 having the above-mentioned configuration, the base layer 12 is formed using a modified polyamideimide resin obtained by copolymerizing the above (A) to (C), and contains polyalkyleneimine and polyoxyethylene alkyl ether. Since a polydimethylsiloxane structure is incorporated into the modified polyamideimide resin by (C), the bending resistance of the endless belt 10 is improved and the friction coefficient can be reduced. Furthermore, by using the modified polyamideimide resin together with polyalkyleneimine and polyoxyethylene alkyl ether, it is possible to improve the releasability while maintaining the friction coefficient.

[0067] The endless belt according to the present invention may have a base layer 12 and a surface layer 14 as shown in FIG. 1, or may be composed of only the base layer 12 and not have the surface layer 14. Also, another layer may be present between the base layer 12 and the surface layer 14. Examples of the other layer include a layer composed of a resin and a layer composed of a rubber. These may be one layer or two or more layers. Examples of the resin include fluorine-based resins such as polyvinylidene fluoride (PVDF), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and ethylene-tetrafluoroethylene copolymer (ETFE), polyethylene-based resins, polystyrene-based resins, acrylic-based resins, polycarbonate (PC)-based resins, polyamide-based resins, EVA (ethylene-vinyl acetate copolymer)-based resins, and EEA (ethylene-ethyl acrylate copolymer)-based resins. Examples of the rubber include chlorinated polyethylene rubber (CPE), chloroprene rubber (CR), and the like.

[0068] The endless belt according to the present invention is suitably used for applications such as toner image transfer, paper transfer and transport, and photoreceptor substrate in electrophotographic devices employing electrophotographic technology, such as full-color LBPs and full-color PPCs; however, the applications are not limited thereto, and the endless belt can also be used as a transfer belt for monochrome electrophotographic copiers, which are not full-color. EXAMPLES

[0069] 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.

[0070] Example 1 <Preparation of base layer forming material> In a reaction vessel equipped with a stirrer, nitrogen inlet tube, thermometer, and cooling tube, 22 parts by mass of MDI, 29 parts by mass of TODI, 38 parts by mass of trimellitic anhydride, 10 parts by mass of silicone polymer (C), and 280 parts by mass of NMP solvent were charged, and the mixture was heated to 130 ° C. over 1 hour while stirring under a nitrogen stream, and reacted at 130 ° C. for about 5 hours, and then the reaction was stopped to prepare a PAI-NMP solution (solid concentration: 29% by mass). 0.2 parts by mass of polyalkyleneimine, 0.1 parts by mass of polyoxyethylene alkyl ether, and 5 parts by mass of conductive carbon were blended into the prepared PAI-NMP solution, mixed with a stirring blade, and then dispersed in a ball mill to prepare a base layer forming material.

[0071] <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.

[0072] (Examples 2 to 10) 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 ratios shown in the table were used.

[0073] (Comparative Examples 1 to 3) An endless belt was produced in the same manner as in Example 1, except that in the preparation of the base layer forming material, neither polyalkyleneimine nor polyoxyethylene alkyl ether was mixed, and the mixing ratios were as shown in the table.

[0074] (Comparative Examples 4 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, neither polyalkyleneimine nor polyoxyethylene alkyl ether was blended, and zinc stearate was used instead, in the blending ratio shown in the table.

[0075] Comparative Example 6 An endless belt was produced in the same manner as in Example 1, except that in the preparation of the PAI-NMP solution, no silicone polymer was added and the mixing ratio was set as shown in the table.

[0076] 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 (B1), Mn: 192.12 Silicone polymer (C): Single-terminated bifunctional silicone polymer with two hydroxyl groups at one end: Shin-Etsu Chemical Co., Ltd. "X-22-176DX", acid value: 30 mg KOH / g, Mn: 3740 Polyalkyleneimine (polyethyleneimine): Nippon Shokubai's "Epomin SP-200", alkylene carbon number 2, Mn=10000 Polyoxyethylene alkyl ether: Nippon Emulsion Co., Ltd. "EMALEX707", alkyl carbon number 12, Mn=495 Zinc stearate: "Zinc Stearate NZ-F" manufactured by Nitto Kasei Kogyo Conductive carbon: Lion Specialty Chemicals' Ketjenblack EC300J

[0077] The endless belt thus produced was used to evaluate the various properties according to the following criteria.

[0078] (Removability) If the cylindrical substrate could be easily removed without air after air was blown between the base layer and the cylindrical substrate, the demoldability was evaluated as good (○); if the substrate was demoldable but it was necessary to constantly blow air during demolding, it was evaluated as △; and if the substrate could not be removed or the base layer was torn, it was evaluated as poor (×).

[0079] (Static friction coefficient) The static friction coefficient of each endless belt was measured using a STATIC FRICTION TESTER μs (Heydon "Type 94i") The static friction coefficient of 0.04 or more and 0.4 or less was marked as "○", and the rest was marked as "×".

[0080] (Bending resistance) In accordance with JIS P8115, the MIT number of each endless belt was measured using a Folding Endurancetester MIT-D (manufactured by Toyo Seiki) under a load of 9.8 N. The MIT number is an index for evaluating bending resistance, and the higher the MIT number, the better the bending resistance. An MIT number of 1000 or more was marked as "○", and an MIT number of less than 1000 was marked as "×".

[0081] [Table 1]

[0082] [Table 2]

[0083] In Comparative Examples 1 to 3, polyalkyleneimine or polyoxyethylene alkyl ether is not blended with the modified polyamideimide resin in the base layer forming material, and the demolding property is poor. In Comparative Examples 4 to 5, polyalkyleneimine or polyoxyethylene alkyl ether is not blended with the modified polyamideimide resin in the base layer forming material, and zinc stearate is blended instead. In Comparative Examples 4 to 5, the friction coefficient is significantly reduced and the friction coefficient is not maintained within a suitable range. In addition, the number of MIT tests is very small, and the flex resistance is also poor. This is presumably because the compatibility between the modified polyamideimide resin and zinc stearate is poor, which causes a reduction in the friction coefficient due to bleeding of zinc stearate, and because the flex resistance is reduced due to a decrease in physical properties. In Comparative Example 6, silicone polymer is not blended in the preparation of the PAI-NMP solution, and the friction coefficient is too large. In addition, the demolding property is also poor. In addition, the rigidity is too high, which causes poor flexing property and poor flex resistance.

[0084] On the other hand, in the examples, polyalkyleneimine and polyoxyethylene alkyl ether are blended with the modified polyamideimide resin, and the examples have excellent demolding properties, a friction coefficient within a suitable range, and excellent flex resistance.

[0085] According to the examples and comparative examples, it is clear that by using a polyalkyleneimine and a polyoxyethylene alkyl ether together with a modified polyamideimide resin, excellent demoldability can be achieved while maintaining the coefficient of friction.

[0086] In comparison between the Examples, it is found that the bending resistance is improved by increasing the amount of silicone polymer (Examples 1 to 6). It is also found that the demoldability is decreased and the friction coefficient is increased by decreasing the amount of polyalkyleneimine or polyoxyethylene alkyl ether (Examples 1 and 7). It is also found that the friction coefficient is decreased by increasing the amount of polyalkyleneimine or polyoxyethylene alkyl ether (Examples 1, 8 to 10). It is also found that when the amount of polyalkyleneimine is 0.2 parts by mass or more and 20 parts by mass or less and the amount of polyoxyethylene alkyl ether is 0.1 parts by mass or more and 5 parts by mass or less relative to 100 parts by mass of modified polyamideimide resin, it is possible to highly achieve both the effect of maintaining the friction coefficient and the effect of improving the demoldability (Examples 1 to 6).

[0087] 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]

[0088] 10 Endless belt 12 Base layer 14 Surface layer

Claims

1. An endless belt for electrophotographic equipment, the belt being driven in a circumferential direction with the surface in contact with or in close proximity to a photoreceptor, The endless belt for electrophotographic equipment, wherein the base layer is formed using a modified polyamideimide resin obtained by copolymerizing the following (A) to (C), and contains a polyalkyleneimine and a polyoxyethylene alkyl ether: (A) Aromatic isocyanate compound (B) Anhydride of aromatic polycarboxylic acid (C) A silicone polymer having a polydimethylsiloxane structure in the molecule, the silicone polymer having a reactive group for the isocyanate group of (A) at one or both ends.

2. 2. The endless belt for electrophotographic equipment according to claim 1, wherein the amount of the polyalkyleneimine is from 0.2 to 20 parts by mass and the amount of the polyoxyethylene alkyl ether is from 0.1 to 5 parts by mass, based on 100 parts by mass of the modified polyamideimide resin.

3. 3. The endless belt for electrophotographic equipment according to claim 1, wherein said silicone polymer (C) has a total of two reactive groups, at least one of a hydroxyl group and a carboxyl group, at one end.

4. 3. The endless belt for electrophotographic equipment according to claim 1, wherein the blending ratio of said silicone polymer (C) is 1% by mass or more and 20% by mass or less based on the total amount of said components (A) to (C).

5. 3. The endless belt for electrophotographic equipment according to claim 1, wherein the number of carbon atoms in the alkylene of said polyalkyleneimine is 2 or more and 4 or less.

6. 3. The endless belt for electrophotographic equipment according to claim 1, wherein the number of carbon atoms in the alkyl group of said polyoxyethylene alkyl ether is 8 or more and 16 or less.

7. the polyalkyleneimine is present in an amount of 0.2 parts by mass or more and 20 parts by mass or less, and the polyoxyethylene alkyl ether is present in an amount of 0.1 parts by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the modified polyamideimide resin; The silicone polymer (C) has a total of two reactive groups, at least one of a hydroxyl group and a carboxyl group, at one end, the blending ratio of the silicone polymer of (C) is 1% by mass or more and 20% by mass or less based on the total amount of (A) to (C); the number of carbon atoms of the alkylene of the polyalkyleneimine is 2 or more and 4 or less, 2. The endless belt for electrophotographic equipment according to claim 1, wherein the number of carbon atoms in the alkyl group of said polyoxyethylene alkyl ether is 8 or more and 16 or less.

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