JP5701128B2 - Conductive endless belt and manufacturing method thereof - Google Patents

Description

  The present invention relates to a conductive endless belt used as an intermediate transfer belt, a paper conveyance transfer belt, and the like in an electrophotographic color printer.

  A conventional transfer belt is a transfer belt using a thermoplastic resin which can be continuously produced mainly and has a low production cost, and many of them have a single layer structure. However, due to the single layer structure, inorganic fillers such as titanium oxide used as an external additive in toner and calcium carbonate contained in PPC paper accumulate on the belt surface, and there is a problem that image defects such as defective cleaning occur. is there.

  In order to solve these problems, a multilayer intermediate transfer belt having a surface layer on a base layer has been proposed. For example, in Patent Document 1, in a conductive endless belt having a multilayer structure having a base layer and a surface layer, the surface layer is a hard coat layer having a pencil hardness of 4H or more and an n-dodecane contact angle of 20 ° or more. Conductive endless belts have been proposed.

  Moreover, in patent document 2, it is a semiconductive seamless belt consisting of at least two layers including the base layer 1 and the surface layer 2, and the base layer 1 includes the following polyethersulfone resin and conductive filler as essential components. The surface layer 2 is formed using a conductive composition, the pencil hardness is set in a range of B to 5H, and the contact angle of pure water is set in a range of 60 ° to 120 °. Conductive endless belts have been proposed.

Furthermore, in patent document 3, it has a layer which consists of either a polyvinylidene fluoride, a vinylidene fluoride copolymer, an ethylene-tetrafluoroethylene copolymer as a base layer as this electroconductive endless belt, and 0. It has an acrylic resin coat layer of 1 to 4.0 μm, the volume resistivity of the belt is 1 × 10 ⁶ to 1 × 10 ¹¹ Ω · cm, and the surface roughness Rz is 0.1 to 5.0 μm. Characteristic conductive endless belts have been proposed.

  However, the above patent document employs an acrylic hard coat agent as the hard coat agent for the surface layer. In general, an acrylic coating agent is mainly accompanied by a chemical reaction such as an ultraviolet curing reaction or an electron beam curing reaction, so that the hardness of the surface layer due to uncuring and bleeding of unreacted resin are generated. There is a risk of causing body contamination, resulting in image defects. Furthermore, as described in Patent Document 1, in the ultraviolet curing type, since the hard coating agent is inhibited from being cured by oxygen in the air, in order to obtain a sufficient effect, the oxygen concentration is set below a certain standard. It must be controlled, and the cost tends to increase in terms of manufacturing equipment.

  Furthermore, an acrylic single film of 4H or higher has sufficient hardness but has a small elongation at break. Therefore, the intermediate transfer belt is durable enough to withstand surface wear due to sliding with paper and driving for each printing. They do not have, and surface cracks occur in the printing durability test.

  In general, single layer polyimide belts and polyamideimide belts have been proposed to prevent accumulation of inorganic fillers such as titanium oxide and calcium carbonate on the belt surface. Since continuous production is not possible and batch production such as rotational molding is performed, production costs increase. In addition, these single-layer polyimide belts and polyamide-imide belts have low elongation at break, so that when the belt is locally stressed during driving, cracks are likely to occur, resulting in the belt breaking. In many cases, the life of the belt is shortened. Therefore, in order to prevent breakage, a treatment such as sticking a reinforcing tape to the end of the belt must be applied, which further increases the cost.

JP 2009-192901 A JP 2004-310016 A JP 2007-206171 A

  In contrast to such background art, the present invention provides an image of poor cleaning and the like due to accumulation of inorganic fillers such as titanium oxide used as an external additive in toner and calcium carbonate contained in PPC paper on the belt surface. It is an object of the present invention to provide a conductive endless belt that eliminates the problem of defects and has durability at low cost.

  As a result of intensive studies to achieve the above object, the present inventor can solve the above-mentioned problems by using a conductive endless belt having a base layer containing a polyamide resin and a surface layer containing an aromatic polyimide resin. I found it. As a result of further research based on this knowledge, the present invention has been completed.

That is, this invention provides the following electroconductive endless belt and its manufacturing method.
Item 1. A conductive endless belt having a base layer containing a polyamide resin and a surface layer containing an aromatic polyimide resin.
Item 2. Item 2. The conductive endless belt according to Item 1, wherein the aromatic polyimide resin is a polyamideimide resin.
Item 3. Item 3. The conductive endless belt according to Item 1 or 2, wherein the base layer contains an inorganic filler.
Item 4. Item 4. The conductive endless belt according to any one of Items 1 to 3, wherein the surface layer has a thickness of 0.5 to 1.3 µm.
Item 5. Item 5. The conductive endless belt according to any one of Items 1 to 4, wherein the surface layer has a surface roughness (Rz) of less than 1.0 µm.
Item 6. Item 6. The conductive endless belt according to any one of Items 1 to 5, wherein the surface layer has a glossiness of 70 or more at an incident angle of 60 °.
Item 7. Item 7. The conductive endless belt according to any one of Items 1 to 6, wherein the surface layer is formed by coating.
Item 8. Item 8. The conductive endless belt according to any one of Items 1 to 7, wherein the surface resistivity is 1 × 10 ⁶ Ω / □ to 1 × 10 ¹⁴ Ω / □.
Item 9. Item 9. The conductive endless belt according to any one of Items 1 to 8, wherein the volume resistivity is 1 × 10 ⁴ Ω · cm to 1 × 10 ¹⁴ Ω · cm.
Item 10. Item 10. The conductive endless belt according to any one of Items 1 to 9, which is an intermediate transfer belt in a color image forming apparatus.
Item 11. A method for producing a conductive endless belt, comprising a base layer containing a polyamide resin and a surface layer containing an aromatic polyimide resin, including the following steps (1) and (2);
(1) a step of forming a base layer by extruding a base layer forming composition containing a polyamide resin and a conductive agent, and if necessary an inorganic filler, and (2) a surface layer forming composition containing an aromatic polyimide resin, The process of laminating | stacking on the outer surface of the base layer obtained by said (1), and forming a surface layer.
Item 12. Item 12. The production method according to Item 11, wherein in the step (2), the surface layer is formed by dissolving the aromatic polyimide resin in a solvent and coating the surface layer forming composition on the outer surface of the base layer.
Item 13. A method for producing a conductive endless belt having a base layer containing a polyamide resin and a surface layer containing an aromatic polyimide resin, including the following steps (1) to (3);
(1) A step of forming a base layer by extruding a base layer forming composition containing a polyamide resin and a conductive agent, and if necessary, an inorganic filler;
(2) A step of forming a surface layer by centrifugally forming a surface layer-forming composition containing an aromatic polyimide resin using a cylindrical mold, and (3) on the inner surface of the surface layer obtained in (2) above The process of heat-treating the outer surface of the base layer obtained in (1) above.

  The conductive endless belt of the present invention can form a stable surface layer without undergoing a chemical reaction such as a curing reaction on the base layer by containing an aromatic polyimide resin in the surface layer, and can prevent filming. . Further, since the wear amount of the belt is small in the wear test with the PPC paper, the durability is excellent. Furthermore, since a polyamide resin that can be continuously produced is used for the base layer, it can be manufactured at low cost.

It is a schematic diagram of the electroconductive endless belt of the multilayer structure of this invention.

Hereinafter, the present invention will be described in detail.
1. Conductive Endless Belt The conductive endless belt of the present invention is an endless belt having a multilayer structure in which a surface layer containing an aromatic polyimide resin is formed on the outer surface of a base layer containing a polyamide resin. An intermediate layer including an elastic rubber layer or the like may be provided between the base layer and the surface layer.
Hereinafter, each layer will be described.

(A) Base layer The base layer of the present invention contains a polyamide resin. The base layer is a layer in which a conductive agent is dispersed in a polyamide resin, and is formed by a base layer forming composition containing the polyamide resin and the conductive agent.

  The polyamide resin is not particularly limited, and various known resins can be used. For example, polyamide 6 (poly (ε-caprolactam)), polyamide 66 (polyhexamethylene adipamide), polyamide 610 (polyhexamethylene sebacamide), polyamide 11 (poly (undecanlactam)), polyamide 12 (poly ( Lauryl lactam)) and the like, and copolymers thereof, for example, polyamide 6-66 copolymers, polyamide 6-610 copolymers, and the like, and aliphatic polyamide resins. These polyamide resins can be used alone or in combination of two or more.

  Among these, it is preferable to use a polyamide resin having a low water absorption rate. By using a polyamide resin having a low water absorption rate, it is possible to suppress dimensional fluctuations due to the environment, and therefore it is possible to reduce environmental fluctuations in the electrical resistance value of the conductive endless belt obtained. The water absorption here means the weight increased per unit weight of the sample after drying the sample in a drying oven at 100 ° C. for 24 hours and leaving it in an environment of 23 ° C. and 50% RH for 24 hours. Point to. The water absorption rate is 1.0 wt% or less, preferably 0.8 wt% or less.

  Examples of the polyamide resin having a small water absorption rate (1.0 wt% or less) include polyamide 11 (water absorption rate 0.9 wt%), polyamide 12 (water absorption rate 0.8 wt%), and the like. Particularly preferred is polyamide 12.

  The MFR (2.16 kgf, 235 ° C.) of the polyamide resin is not particularly limited as long as it can be formed into a tube shape, but is usually 10 to 30 g / 10 min, preferably 15 to 25 g / 10 min. More preferably, it is 18-22 g / 10min.

  As the conductive agent dispersed in the base layer of the present invention, a known electronic conductive material or ionic conductive material can be used.

  Examples of the electronic conductive material include carbon black, SAF, ISAF, HAF, FEF, GPF, SRF, FT, MT, and other rubber carbon, color (ink) carbon subjected to oxidation treatment, pyrolytic carbon, Examples thereof include natural graphite, artificial graphite, antimony-doped tin oxide, titanium oxide, zinc oxide, nickel, copper, silver, germanium, and other metals and metal oxides, polyaniline, polypyrrole, polyacetylene, and other conductive polymers.

  Examples of the ion conductive substance include inorganic ionic conductive substances such as sodium perchlorate, lithium perchlorate, calcium perchlorate, and lithium chloride, tridecylmethyldihydroxyethylammonium perchlorate, lauryltrimethylammonium perchlorate. , Modified aliphatic dimethylethylammonium ethosulphate, N, N-bis (2-hydroxyethyl) -N- (3′-dodecyloxy-2′-hydroxypropyl) methylammonium ethosulphate, 3-lauramidepropyl-toeimethyl Ammonium methyl sulfate, stearamidopropyldimethyl-β-hydroxyethyl-ammonium dihydrogen phosphate, tetrabutylammonium borofluoride, stearyl ammonium acetate Quaternary ammonium perchlorates such as lauryl ammonium acetate, sulfates, ethosulphate salts, methyl sulfate salts, phosphates, borofluoride salts, organic ionic conductive materials such as acetates, or charge transfer complexes Is mentioned.

  These conductive agents can be used alone or in combination of two or more.

  Of the conductive agents, carbon black is preferably used. Examples of carbon black include gas black, acetylene black, oil furnace black, thermal black, channel black, and ketjen black. Examples of effective means for obtaining a desired conductivity with a smaller amount of mixing include ketjen black, acetylene black and oil furnace black. Ketjen black is a contact furnace carbon black.

  Conductivity can be imparted to the base layer using the above conductive agent as appropriate. The content of the conductive agent varies depending on the desired surface resistivity of the base layer, but is 5 to 50% by weight, preferably 8 to 40% by weight, in 100% by weight of the polyamide resin composition forming the base layer. In the case of using the above electronic conductive material as the conductive agent, it is 6 to 20% by weight, preferably 8 to 12% by weight, in 100% by weight of the polyamide resin composition forming the base layer. When the ion conductive substance is used as the conductive agent, it is preferably used in an amount of 10 to 50% by weight, particularly 20 to 40% by weight, in 100% by weight of the polyamide resin composition forming the base layer.

The surface resistivity of the base layer is, for example, 1 × 10 ⁶ to 1 × 10 ¹⁴ (Ω / □), preferably 1 × 10 ⁸ to 1 × 10 ¹⁴ (Ω / □) using the above conductive agent as appropriate. Can be controlled. The said surface resistivity can be measured with the measuring method described in the Example, for example.

Further, the volume resistivity of the base layer can be controlled to, for example, 1 × 10 ⁴ to 1 × 10 ¹⁴ (Ω · cm), preferably 1 × 10 ⁶ to 1 × 10 ¹³ (Ω · cm). The volume resistivity can be measured, for example, by the measurement method described in the examples.

  Moreover, an inorganic filler can also be added to the base layer of the present invention. The inorganic filler is not particularly limited, and various known inorganic fillers that can be added to the resin can be used. Examples include talc, mica, calcium carbonate, silica, glass fiber, and titanium oxide. In particular, talc is preferable from the viewpoint of compatibility with the polyamide resin. Furthermore, in order to improve the compatibility of the inorganic filler with the polyamide resin, the inorganic filler can be appropriately subjected to a surface treatment. Examples of the surface treatment method include known treatments with a coupling agent such as a silane coupling agent, a titanate coupling agent, an aluminum coupling agent, and a zirconium coupling agent.

  By appropriately adding the above inorganic filler, the tensile elastic modulus of the base layer can be improved. For example, the tensile elastic modulus (based on JIS K7127) can be 2.0 GPa or more, and further 2.0 to 2.5 GPa. The said tensile elasticity modulus can be measured with the measuring method described in the Example, for example. When the tensile elastic modulus is 2.0 GPa or more, it is possible to suppress elongation due to stretching of the obtained conductive endless belt on the drive roll, that is, to improve creep characteristics.

  In addition, by appropriately adding the above inorganic filler, although the tensile break strength of the base layer is reduced, for example, the tensile break strength can be 100% or more, and further 100 to 150%. The said tensile breaking strength can be measured with the measuring method described in the Example, for example. When the tensile breaking strength is 100% or more, the obtained conductive endless belt is durable even when a load is locally applied to the belt end during driving of the belt, and the end of the belt is not broken. Excellent.

  The addition amount of the inorganic filler varies depending on the desired physical properties, but is usually 20% by weight or less, preferably 5 to 20% by weight, more preferably 5% in 100% by weight of the polyamide resin composition forming the base layer. ~ 15% by weight.

  Specifically, when the conductive agent and the inorganic filler are used in combination, when the conductive agent is an electronic conductive material, the electronic conductive material is 6 to 20% by weight in 100% by weight of the polyamide resin composition forming the base layer, preferably 8 to 12% by weight, inorganic filler 0 to 20% by weight, preferably 5 to 15% by weight. When the conductive agent is an ion conductive material, the ion conductive material is 10 to 50% by weight, preferably 20 to 40% by weight, and the inorganic filler is 0 to 20% by weight in 100% by weight of the polyamide resin composition forming the base layer. %, Preferably 5 to 15% by weight.

  The thickness of the base layer is 100 to 140 μm, preferably 110 to 130 μm. If the thickness is 100 μm or more, the handleability of the belt is good, there are few defects, and the yield is good. Moreover, if the said thickness is 140 micrometers or less, it is excellent in handling property and manufacturing cost.

  In the base layer, known additives added to the resin as necessary, for example, antioxidants, heat stabilizers, plasticizers, light stabilizers, lubricants, antifogging agents, antiblocking agents, slipping agents. , A crosslinking agent, a crosslinking aid, an adhesive, a flame retardant, a dispersant and the like can be appropriately blended.

(B) Surface layer The surface layer of the present invention contains an aromatic polyimide resin. The surface layer is formed by a surface layer forming composition containing an aromatic polyimide resin.

  Examples of the aromatic polyimide resin include those having an imide group in the main skeleton such as aromatic polyimide, aromatic polyamideimide, and aromatic polyesterimide. Furthermore, silicone modified polyimide copolymerized with soft segments, urethane modified polyimide, and the like are also included. Among these, an aromatic polyamideimide resin that is excellent in moldability is preferable.

  The aromatic polyamide-imide resin is not particularly limited, and various known ones can be used. Usually, an aromatic polyamideimide resin is produced by condensation polymerization of an acid component typified by trimellitic anhydride and an aromatic diamine or aromatic diisocyanate by a known method. Therefore, the said acid component and aromatic diamine or aromatic diisocyanate can be dissolved in a solvent, and it can be set as the surface layer forming composition of this invention.

  Examples of the solvent used in this case include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphonyltriamide, cyclohexanone, γ-butyrolactone, methyl alcohol, tetrahydrofuran, ethanol, xylene and the like. Is mentioned. If necessary, phenols such as cresol, phenol and xylenol, and hydrocarbons such as hexanebenzene and toluene may be mixed. These may be used alone or as a mixture of two or more. A preferred organic solvent is N, N-dimethylacetamide.

  Acid components used in the surface layer-forming composition include trimellitic acid and its anhydride or acid chloride, pyromellitic acid, biphenyltetracarboxylic acid, biphenylsulfonetetracarboxylic acid, benzophenonetetracarboxylic acid, biphenylethertetracarboxylic acid. Tetracarboxylic acids such as acid, ethylene glycol bistrimellitate, propylene glycol bistrimellitate and their anhydrides, oxalic acid, adipic acid, malonic acid, sebacic acid, azelaic acid, dodecanedicarboxylic acid, dicarboxypolybutadiene, dicarboxypoly (Acrylonitrile-butadiene), aliphatic dicarboxylic acids such as dicarboxypoly (styrene-butadiene), aliphatic carboxylic acids such as cyclohexanecarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1, Arocyclic dicarboxylic acids such as 3-cyclohexanedicarboxylic acid, 4,4'-dicyclohexylmethanedicarboxylic acid, dimer acid, etc., terephthalic acid, isophthalic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, naphthalenedicarboxylic acid, etc. Can be given. These may be used alone or in combination of two or more. Of these, trimellitic anhydride is preferably used.

  Examples of the aromatic diamine include m-phenyldiamine, p-phenyldiamine, 2,4-aminotoluene, 2,6-aminotoluene, 2,4-diaminochlorobenzene, m-xylylenediamine, and p-xylylenediamine. Amine, 1,4-diaminonaphthalene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4′-diaminonaphthalene biphenyl, benzidine, 3,3-dimethylbenzidine, 3,3′-dimethoxybenzidine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether (ODA), 4,4'-diaminodiphenyl sulfide, 3,3'-diaminobenzophenone, 4,4'-diaminophenyl sulfone, 4,4'- Diaminoazobenzene, 4,4'-diaminodiphenylmethane Bis-aminophenyl propane. Preferably, it is a polyamide-imide resin obtained using p-phenyldiamine or 4,4'-diaminodiphenyl ether (ODA) as the aromatic diamine component.

  Moreover, as said aromatic diisocyanate, the compound etc. which the amino group in the above-mentioned aromatic diamine substituted by the isocyanate group are mentioned. For example, diisocyanates of aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, alicyclic diamines such as 1,4-cyclohexanediamine, 1,3-cyclohexanediamine, isophoronediamine, and 4,4′-dicyclohexylmethanediamine. Diisocyanate, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylmethane, 4,4-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone, benzidine, o-tolidine, 2,4-tolylenediamine, Examples thereof include diisocyanates of aromatic diamines such as 2,6-tolylenediamine and xylylenediamine. These may be used alone or in combination of two or more.

  Preferably, it is a polyamide-imide resin obtained by using 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, or isophorone diisocyanate as the aromatic diisocyanate component.

  In addition, the surface layer may be a known additive added to the resin as necessary, for example, an antioxidant, a heat stabilizer, a light stabilizer, a lubricant, an antifogging agent, a slip agent, a flame retardant, a surface conditioner. Etc. can be appropriately blended. The surface conditioner is oriented on the surface of the coating film in the drying process, uniforms the surface tension of the coating film, prevents floating mottle and repellency, and improves wetting on the object to be coated. Specifically, for example, commercially available acrylic surface conditioners and silicone surface conditioners can be used.

  The addition amount of the known additive is usually 0.01% by weight or less in the aromatic polyimide resin composition forming the surface layer.

  Further, the thickness of the surface layer is usually 0.5 to 1.3 μm, preferably 0.8 to 1.0 μm. When the thickness is 0.5 to 1.3 μm, when used as a transfer belt, there is no risk of the surface layer being scraped by abrasion with the cleaning blade and paper, and the voltage applied during transfer attenuates after transfer. There is no fear that the charge of the previous image remains when the next image is formed.

  The tensile elastic modulus of the surface layer can be 1.5 GPa or more. If it is 1.5 GPa or more, there is an effect on filming, and if it is 2.0 GPa or more, it is further excellent in filming resistance. The said tensile elasticity modulus can be measured with the measuring method described in the Example, for example.

  The tensile breaking elongation of the surface layer can be 10% or more. If it is 10% or more, the bending resistance is good. In particular, when it is 20% or more, the bending resistance is further improved. The said tensile breaking strength can be measured with the measuring method described in the Example, for example.

Various physical property values of the conductive endless belt The conductive endless belt of the present invention has the following physical property values.
The total thickness (total thickness) of the conductive endless belt is usually 100 to 140 μm, preferably 110 to 130 μm, and more preferably 115 to 125 μm. By being in the said range, it can be set as the electroconductive endless belt excellent in handling property and manufacturing cost.

The surface resistivity of the conductive endless belt is preferably controlled to 1 × 10 ⁶ to 10 ¹⁴ (Ω / □), preferably 1 × 10 ⁸ to 10 ¹⁴ (Ω / □). The said surface resistivity can be measured with the measuring method described in the Example, for example.

The volume resistivity of the conductive endless belt can be controlled to 1 × 10 ⁴ to 1 × 10 ¹⁴ (Ω · cm), preferably 1 × 10 ⁶ to 1 × 10 ¹³ (Ω · cm). The volume resistivity can be measured, for example, by the measurement method described in the examples.

  The surface roughness (Rz) of the surface layer of the conductive endless belt of the present invention is preferably less than 1.0 μm. If the thickness is less than 1.0 μm, toner does not slip through the cleaning blade, and image defects are less likely to occur. Since the surface roughness of the surface layer is affected by the surface roughness of the base layer, if the surface roughness of the base layer is small, the surface roughness of the surface layer is also small. Further, when a low molecular weight polyamideimide is used for the surface layer, the surface roughness tends to be small. Furthermore, the influence of the coating liquid viscosity is also considered. If the coating liquid viscosity is small, the surface roughness of the formed surface layer tends to be small. The said surface roughness (Rz) can be measured with the measuring method described in the Example, for example.

  Furthermore, the glossiness of the surface layer of the conductive endless belt of the present invention is preferably 70 or more with respect to a 60 ° incident angle. If the glossiness is 70 or more, the optical sensor for toner density correction functions and printing can be performed with high image quality. Since the glossiness of the surface layer is inversely proportional to the surface roughness of the surface layer, the glossiness increases when the surface roughness is small. The said glossiness can be measured with the measuring method described in the Example, for example.

  The wear amount of the conductive endless belt of the present invention is preferably 0.5 mg or less. If it is 0.5 mg or less, the surface layer can be maintained for a long time with little damage to the surface layer due to sliding of the PPC paper and the cleaning blade due to printing. The amount of wear is affected by the type of raw material used for the surface layer. The amount of wear can be measured, for example, by the measurement method described in the examples.

  Furthermore, the bending resistance of the endless belt of the present invention is preferably 30,000 times or more. If it is 30,000 times or more, there is no cracking of the belt due to bending during driving, and the durability is excellent. The crack of the belt is affected by the raw material used for the base layer. The bending resistance can be measured by, for example, the measuring method described in the examples.

2. A method for producing a conductive endless belt having the above-described configuration is not particularly limited, and examples thereof include the following methods.

The conductive endless belt of the present invention can be obtained by a production method including the following steps.
(1) A step of forming a base layer by extruding a base layer forming composition containing a polyamide resin and a conductive agent, and if necessary, an inorganic filler;
(2) A step of forming a surface layer by centrifugally forming a surface layer composition containing an aromatic polyimide resin using a cylindrical mold, and (3) on the inner surface of the surface layer obtained in (2) above, A step of superposing and bonding the outer surfaces of the base layer obtained in the above (1) by adhesion or heating.

  Alternatively, the surface layer composition containing (2 ′) aromatic polyimide resin is laminated on the outer surface of the base layer obtained in (1) above to form the surface layer on the base layer formed in (1) above. Can be manufactured.

  Hereinafter, each step will be described. In addition, the raw material used in the manufacturing method of this invention, its content, etc. are as above-mentioned.

Step (1) (Formation of base layer)
The base layer containing a polyamide resin can be produced by extruding a base layer composition containing a polyamide resin, a conductive agent and, if necessary, an inorganic filler. For example, it can be manufactured as follows.

  First, a base resin composition is prepared by mixing a polyamide resin, a conductive agent, and an inorganic filler as required. A known mixing means can be applied to the mixing, and for example, a twin screw extruder can be used. When using a twin-screw extruder, it is preferable to heat-knead at a barrel temperature of about 160 to 250 ° C. and sufficiently disperse and mix.

  Next, the base layer composition is extruded. A known extrusion molding means can be applied to the extrusion molding, and for example, a single screw extruder and a circular mandrel die for extrusion molding can be used. The thickness of the obtained base layer can be adjusted by appropriately setting the lip width and extrusion molding conditions of the circular mandrel. In order to accurately maintain the shape of the tube after discharge, a mandrel such as an air ring may be used at the die outlet. Moreover, an endless belt can be formed at a time by installing a circular mandrel die at the tip of the twin-screw extruder.

  Since the base layer is obtained as a continuous tube by the extrusion molding, when it is used as an intermediate transfer belt, it is traversed with a necessary width so that it can be used as a belt.

Step (2) (formation of surface layer)
The surface layer containing the aromatic polyimide resin can be formed as follows, for example.

  First, the aromatic polyimide resin and the above 1. The known additives described in (b) are the above-mentioned 1 .. Dissolve in the solvent described in (b) to prepare a surface layer forming composition. The aromatic polyimide resin in the surface layer-forming composition is usually preferably 5 to 30% by mass, particularly preferably 10 to 20% by mass, as the solid content concentration. Here, the solid content concentration is a value obtained by dividing the weight of the solid in the case where the solid is dissolved in an organic solvent by the weight of the solution, and is expressed in percent (%).

  Next, the surface layer forming composition is subjected to centrifugal molding using a cylindrical mold having a surface roughness (Rz) of 0.25 to 1.25 μm. In this case, it adjusts so that the thickness of the surface layer obtained may be set to about 0.5-1.3 micrometers.

  For example, the surface layer is formed by centrifuging the surface of the rotating drum (cylindrical mold) rotated to a centrifugal acceleration of 0.5 to 10 times the gravitational acceleration. The rotation speed is gradually increased, the rotation is increased to a centrifugal acceleration of 2 to 20 times the gravitational acceleration, and the entire inner surface is cast by centrifugal force.

  The inner surface of the rotating drum is polished to a predetermined surface accuracy, and the surface state of the rotating drum is almost transferred to the outer surface of the conductive endless belt of the present invention. Therefore, the surface roughness of the surface layer can be adjusted to a desired range by controlling the surface roughness of the inner surface of the rotating drum. When the average surface roughness (Rz) of the inner surface of the rotating drum is set in the range of 0.25 to 1.5 μm, a surface layer having a surface roughness (Rz) of 0.25 to 1.5 μm corresponding to that can be formed. . However, the surface roughness of the surface layer of the conductive endless belt is slightly higher than the average surface roughness (Rz) of the inner surface of the rotating drum because it picks up subtle waviness and undulation of the belt. Tend. Therefore, it is possible to employ a rotating drum having a slightly smaller average surface roughness (Rz) of the inner surface relative to the desired surface roughness of the belt surface layer. Note that the roughness of the inner surface of the mold to be used can be arbitrarily controlled by the count of the abrasive paper used when finishing the inner surface.

  The rotating drum is placed on a rotating roller, and is rotated indirectly by the rotation of the roller. The size of the drum can be appropriately selected according to the desired size of the conductive endless belt.

  Heating is performed by indirect heating from the outside with a heat source such as a far infrared heater disposed around the drum. The heating temperature may vary depending on the type of the resin, but is usually about (Tm ± 40) ° C., preferably (Tm-40) when the temperature is from room temperature to around the melting point of the resin, for example, the melting point Tm of the resin. ) Gradually raise the temperature to about C to Tm ° C. and heat at the temperature after the temperature increase for about 10 to 240 minutes. Thereby, a seamless (seamless) tubular surface layer can be formed on the inner surface of the drum.

Step (3) (2 layers)
The outer surface of the base layer obtained in the step (1) and the inner surface of the surface layer obtained in the step (2) are superposed and heat-treated.

  Specifically, a known adhesion primer or the like is applied to the inner surface of the surface layer formed in the rotating drum and air-dried, and then a base layer coated with a dry lamination adhesive or the like is inserted into the outer surface and overlapped. After the two superimposed layers are pressure-bonded from the inner surface of the belt, the inner surface of the cylindrical mold is gradually heated to reach about 90 to 150 ° C, preferably about 90 to 120 ° C.

  The temperature raising rate may be about 1 to 3 ° C./min, for example. A two-layer belt having a surface layer and a base layer in a cylindrical mold is formed by maintaining at the above temperature for 20 to 240 minutes.

  Alternatively, instead of using an adhesive, it can be fused by applying heat. The heating temperature may be about 170 to 220 ° C., and the heating time may be about 60 to 240 minutes.

  The laminated two-layer belt is peeled off from the cylindrical mold, and both ends are cut to a desired width to produce a two-layer conductive endless belt.

  Moreover, in the said manufacturing method, it replaces with the said process (2) and (3), and also laminate | stacks the surface layer formation composition containing an aromatic polyimide resin on the outer surface of the base layer obtained at the process (1). The conductive endless belt of the present invention can be produced (2 ′).

Step (2 ′) (formation of surface layer and double layering)
The surface layer containing an aromatic polyimide resin can be produced by laminating a surface layer forming composition containing an aromatic polyimide resin and a solvent on the outer surface of the base layer.

  Specifically, a surface layer forming composition is coated on the outer surface of the base layer. As the coating method, any of the known spray coating method, dip coating method, flow coating method and the like may be used. For example, it can be manufactured as follows.

  First, the aromatic polyimide resin and, if necessary, the known additive described in the above (b) are dissolved in the solvent described in the above (b) such as N, N-dimethylacetamide, and the surface layer forming composition is obtained. Prepare.

  The aromatic polyimide resin in the surface layer-forming composition is usually preferably 5 to 30% by mass, particularly preferably 10 to 20% by mass, as the solid content concentration. Here, the solid content concentration is a value obtained by dividing the weight of the solid in the case where the solid is dissolved in an organic solvent by the weight of the solution, and is expressed in percent (%).

  Next, the said surface layer forming composition is laminated | stacked on the outer surface of a base layer.

Specifically, after the base layer is sheathed on a metal mandrel, the mandrel with the base layer outer layer immersed in a bath filled with a solution of the surface layer forming composition separately perpendicularly to the bath, and then at a constant speed. By pulling up, a surface layer is formed on the base layer. It is known that the thickness of the surface layer on the base layer is proportional to the thickness (h) of the coating film before drying, and the thickness is related to the density (d) and viscosity (η) of the coating solution and the lifting speed (u). There is a relationship represented by the following formula (1).
h = a (ηu / dg) ^1/2 (1)
(Here, g represents gravitational acceleration.)

  Thereafter, the surface layer is fixed on the base layer by putting in a heating furnace such as an oven and drying the solvent of the surface layer coating solution. For example, it is good to dry on the conditions of 90-200 degreeC and 60-240 minutes.

  If the adhesion between the base layer and the surface layer is insufficient, the outer peripheral surface of the base layer can be surface-treated by high-frequency plasma, corona discharge, sandblasting, etc. as a coating pretreatment to improve the adhesion with the surface layer. it can.

EXAMPLES Hereinafter, although an Example etc. are shown and this invention is demonstrated in detail, this invention is not limited to these.
In the present invention, each value was measured as follows.

(Solid content concentration)
The aromatic polyimide resin forming the surface layer is precisely weighed, and the weight at this time is Cg. In order to dissolve the resin in the solvent on the electronic balance, the solvent is gradually added while stirring, and the solid content concentration when the final solution weight is Dg is represented by the following formula (I).
Solid content concentration = C / D × 100 (%) (I)

(Surface resistivity)
<Measurement device>
Resistance meter: Hiresta-UP (Mitsubishi Chemical Corporation)
Electrode: URS probe (Mitsubishi Chemical Corporation)
<Measurement conditions>
Measurement atmosphere: 23 ° C./50% RH, applied voltage: 100 V, applied time: 10 sec
The obtained endless belt (diameter: 120 mm, width: 238 mm) was cut open, and 16 points at equal intervals in the center in the width direction and in the circumferential direction were measured using the measuring device and the measuring conditions, and the average value was obtained. The load during measurement was 2.0 kg.

(Volume resistivity)
<Measurement device>
Resistance meter: Hiresta-UP (Mitsubishi Chemical Corporation)
Electrode: URS probe (Mitsubishi Chemical Corporation)
<Measurement conditions>
Measurement atmosphere: 23 ° C./50% RH, applied voltage: 100 V, applied time: 10 sec
The obtained endless belt (diameter: 120 mm, width: 238 mm) was cut open, and 16 points at equal intervals in the center in the width direction and in the circumferential direction were measured using the measuring device and the measuring conditions, and the average value was obtained. The load during measurement was 2.0 kg.

(Belt thickness)
Using a dial gauge with an accuracy of 0.001 mm, an average value was obtained by measuring a total of 16 points, one at the center in the width direction of the obtained endless belt and 16 at equal intervals in the belt circumferential direction.

(Surface thickness)
<Measurement device>
Laser microscope VK-9510 (manufactured by Keyence Corporation)
The obtained endless belt (diameter: 120 mm, width: 238 mm) was incised, and the cross-section of the belt at 16 points equally spaced in the center in the width direction and in the circumferential direction was observed with the measuring device at a magnification of 3000 times, and then the surface layer thickness was measured. The average value was obtained.

(Tensile modulus)
<Measurement device>
Autograph: AG-500E (manufactured by Shimadzu Corporation)
<Measurement conditions>
Measurement atmosphere: 23 ° C./55% RH, test speed: 50 mm / min, test piece width: 25 mm × 250 mm
Distance between chucks: 200mm
Specimen tensile direction: Belt circumferential direction JIS K7127 compliant Average value of N number 5 The base layer was measured according to the above conditions after being manufactured by the method described in each example and comparative example.
For the surface layer, using the varnish shown in each Example and Comparative Example, selecting the number of a commercially available bar coater so that the film thickness of the varnish after drying was 20 μm, and applying a commercially available silicone release agent A film was formed on a SUS304 plate having a thickness of 1.0 mm, dried in an oven, and then peeled off from the SUS304 plate, and then measured according to the above conditions using a 20 μm surface layer.

(Tensile elongation at break)
<Measurement device>
Autograph: AG-500E (manufactured by Shimadzu Corporation)
<Measurement conditions>
Measurement atmosphere: 23 ° C./55% RH, test speed: 200 mm / min, test piece width: 10 mm × 150 mm
Distance between chucks: 100mm
Specimen tensile direction: Belt circumferential direction JIS K7127 compliant Average value of N number 5 The base layer and the surface layer similar to the tensile elastic modulus were each measured according to the above conditions.

(Glossiness)
<Measurement device>
PG-1M (Nippon Denshoku Industries Co., Ltd.)
<Measurement conditions>
JIS Z8741 compliant Incident angle 60 °
In the obtained conductive endless belt, the surface layer side was measured at 8 points at equal intervals in the center in the width direction and in the circumferential direction, and the average value was obtained.

(Surface roughness (Rz))
<Measurement device>
Surfcom 480A (manufactured by Tokyo Seimitsu Co., Ltd.)
<Measurement conditions>
JIS B0601: 1994 compliant Evaluation length: 4.0 mm, Measurement speed: 0.15 mm / sec, Cut-off: 0.8 mm
In the obtained conductive endless belt, the surface layer side was measured at 8 points at equal intervals in the center in the width direction and in the circumferential direction, and the average value was obtained.

(Bend resistance test)
<Measurement device>
MIT testing machine (manufactured by Toyo Seiki Seisakusho)
<Measurement conditions>
ASTM D-2176 fold angle: 135 °, fold speed: 175 cpm, load: 300 g
<Evaluation method>
MIT test frequency;
○: 30,000 or more Δ: 5,000 or more, less than 30,000 ×: less than 5,000

(Abrasion amount)
The conductive endless belt is cut to 25 mm × 50 mm and then in close contact with the A4 size PPC paper at a pressure of 0.2 kg / cm ² at a speed of 310 mm / sec. The weight difference of the endless belt before and after the slide was measured, and this weight difference was defined as the amount of wear. The evaluation criteria are as follows.
Weight difference;
○: 0.5 mg or less Δ: More than 0.5 mg, 1.2 mg or less ×: More than 1.2 mg

(Bleed-out property, filming resistance, durability)
The conductive endless belts obtained in the following examples and comparative examples were used as intermediate transfer belts and mounted on actual machines (color laser printer “CLP-315k”, manufactured by SAMSUN ELECTRONICS CO., LTD) to produce magenta halftone images. By printing, bleed-out property, filming resistance, and durability were confirmed.
Bleed-out evaluation method;
In a HH environment (32.5 ° C., 85% RH), a printing durability test was performed on 20,000 sheets, and the surface of the photoreceptor and the image were confirmed every 5,000 sheets.
×: Bleed material can be visually confirmed on the surface of the photoconductor and image defect occurs. Δ: Bleed material cannot be confirmed on the surface of the photoconductor, but image defect occurs. ○: Bleed material is also confirmed on the surface of the photoconductor. What can not be done and image defects do not occur Filming resistance evaluation method;
×: Cleaning failure occurs when printing number is less than 10,000. Δ: Cleaning failure occurs when printing number is 10,000 or more and less than 30,000. ○: Printing number is 30,000 or more. Durability evaluation method;
X: When the number of printed sheets is less than 10,000, cracks are generated on the surface or the belt is broken. Δ: When the number of printed sheets is 10,000 or more and less than 30,000, the surface is cracked or the belt is broken.

Example 1
After blending 90% by weight of a polyamide resin (UBESTA PA-12 3020U, manufactured by Ube Industries, Ltd.) and 10% by weight of carbon black (Ketjen Black, manufactured by Ketjen Black International Co., Ltd.), a twin screw extruder. The mixture was charged (cylinder temperature: 160 to 250 ° C.) to produce a pellet-shaped raw material A.
Using a φ50 mm single screw extruder (cylinder temperature: 180-230 ° C.), the pellet A was 376 mm in inner circumference length, 120 ± 7 μm in thickness, 238 mm in width, 1 × 10 ¹⁰ Ω / surface resistivity. A cylindrical tube (base layer) having a volume resistivity of 6 × 10 ⁸ Ω · cm was formed. Thereafter, the outer peripheral surface of the base layer was subjected to corona treatment at 30 W · min / m ² using a high-frequency power source AGF-A60 manufactured by Kasuga Electric Co., Ltd. and an aluminum electrode (effective length: 300 mm).
Next, a polyamideimide resin composed of 1 mol of trimellitic anhydride, 0.7 mol of 4,4′-diphenylmethane diisocyanate, and 0.3 mol of 2,4-tolylene diisocyanate is converted into N, N-dimethylacetamide (DMAc). It was made to melt | dissolve so that it might become 15 mass% of solid content, and the varnish A was obtained.
The above-mentioned surface-treated base layer (width 238 mm, inner peripheral length 376 mm, thickness 120 μm, surface resistivity 1 × 10 ¹⁰ Ω / □, volume resistivity 6 × 10 ⁸ Ω · cm) After covering the metal mandrel, the mandrel covered with the base layer was immersed perpendicularly to the bath in a bath filled with varnish A, and the pulling speed was adjusted so that a surface layer having a thickness of 0.8 μm could be formed. Thereafter, it was dried in an oven to produce a conductive endless belt having the structure shown in FIG.
The conductive endless belt produced above had a thickness of 120.8 μm, a surface resistivity of 3 × 10 ¹⁰ Ω / □, and a volume resistivity of 3 × 10 ⁹ Ω · cm.

Example 2
Polyamide resin (UBESTA PA-12 3020U, manufactured by Ube Industries, Ltd.) 80% by weight, talc (Nanoace KS-873N1000, manufactured by Nippon Talc Co., Ltd.) 10% by weight, and carbon black (Ketjen Black, Ketjen Black International ( (Made by Co., Ltd.) After blending 10% by weight, the mixture was put into a twin screw extruder (cylinder temperature 160 to 250 ° C.) to prepare a pellet raw material B.
Using the pellet B, a circular mandrel die with an inner peripheral length of 376 mm, a thickness of 120 ± 7 μm, a width of 238 mm, and a surface resistivity of 1 × 10 ¹⁰ Ω / φ using a φ50 mm single screw extruder (cylinder temperature: 160 to 250 ° C.) A cylindrical tube (base layer) having a volume resistivity of 6 × 10 ⁸ Ω · cm was formed.
Thereafter, the outer peripheral surface of the base layer was subjected to corona treatment at 30 W · min / m ² using a high-frequency power source AGF-A60 manufactured by Kasuga Electric Co., Ltd. and an aluminum electrode (effective length: 300 mm).
Next, a polyamideimide resin composed of 1 mol of trimellitic anhydride and 1 mol of isophorone diisocyanate was dissolved in γ-butyrolactone so as to have a solid concentration of 15% by mass to obtain varnish B.
The surface-treated base layer (width 238 mm, inner peripheral length 376 mm, thickness 120 μm, surface resistivity 1 × 10 ¹⁰ Ω / □, volume resistivity 6 × 10 ⁸ Ω · cm) obtained above is applied to the varnish B. After covering the metal mandrel, the mandrel covered with the base layer was immersed perpendicularly to the bath in a bath filled with varnish B, and the pulling speed was adjusted so that a surface layer having a thickness of 0.8 μm could be formed. Thereafter, it was dried in an oven to produce a conductive endless belt having the structure shown in FIG.
The conductive endless belt produced above had a thickness of 120.8 μm, a surface resistivity of 3 × 10 ¹⁰ Ω / □, and a volume resistivity of 3 × 10 ⁹ Ω · cm.

Example 3
In the same manner as in Example 2, a base layer (inner peripheral length 376 mm, thickness 120 μm, width 238 mm, surface resistivity 1 × 10 ¹⁰ Ω / □, volume resistivity 6 × 10 ⁸ Ω · cm) was obtained.
Thereafter, the outer peripheral surface of the base layer was subjected to corona treatment at 30 W · min / m ² using a high-frequency power source AGF-A60 manufactured by Kasuga Electric Co., Ltd. and an aluminum electrode (effective length: 300 mm).
Next, a polyamideimide resin composed of 0.5 mol of trimellitic anhydride, 0.5 mol of cyclohexanecarboxylic acid, and 1 mol of isophorone diisocyanate was dissolved in γ-butyrolactone so as to have a solid content concentration of 20% by mass. The solution was gradually added to water while stirring to precipitate a polymer, filtered and dried to obtain a polyamideimide powder. The obtained polyamideimide powder was dissolved in a mixed solvent (1: 1) of methyl alcohol and tetrahydrofuran to obtain varnish C having a solid content concentration of 15% by mass.
The surface-treated base layer (width 238 mm, inner peripheral length 376 mm, thickness 120 μm, surface resistivity 1 × 10 ¹⁰ Ω / □, volume resistivity 6 × 10 ⁸ Ω · cm) obtained above is applied to the varnish C. After covering the metal mandrel, the mandrel with the base layer was immersed perpendicularly to the bath in a bath filled with varnish C, and the pulling speed was adjusted so that a surface layer with a thickness of 0.8 μm could be formed. Thereafter, it was dried in an oven to produce a conductive endless belt having the structure shown in FIG.
The conductive endless belt produced above had a thickness of 120.8 μm, a surface resistivity of 3 × 10 ¹⁰ Ω / □, and a volume resistivity of 3 × 10 ⁹ Ω · cm.

Example 4
In the same manner as in Example 1, a base layer (width 238 mm, inner peripheral length 376 mm, thickness 120 μm, surface resistivity 1 × 10 ¹⁰ Ω / □, volume resistivity 6 × 10 ⁸ Ω · cm) was obtained.
Thereafter, the outer peripheral surface of the base layer was subjected to corona treatment at 30 W · min / m ² using a high-frequency power source AGF-A60 manufactured by Kasuga Electric Co., Ltd. and an aluminum electrode (effective length: 300 mm).
Next, a polyamideimide resin composed of 1 mol of trimellitic anhydride, 0.7 mol of 4,4′-diphenylmethane diisocyanate, and 0.3 mol of 2,4-tolylene diisocyanate is converted into N, N-dimethylacetamide (DMAc). It was made to melt | dissolve so that it might become solid content concentration 18 mass%, and the varnish D was obtained.
The above-mentioned surface-treated base layer (width 238 mm, inner peripheral length 376 mm, thickness 120 μm, surface resistivity 1 × 10 ¹⁰ Ω / □, volume resistivity 6 × 10 ⁸ Ω · cm) After covering the metal mandrel, the mandrel with the base layer was immersed perpendicularly to the bath in a bath filled with varnish D, and the pulling speed was adjusted so that a surface layer having a thickness of 1.2 μm could be formed. Thereafter, it was dried in an oven to produce a conductive endless belt having the structure shown in FIG.
The conductive endless belt produced above had a thickness of 121.2 μm, a surface resistivity of 6 × 10 ¹⁰ Ω / □, and a volume resistivity of 1 × 10 ¹⁰ Ω · cm.

Example 5
In the same manner as in Example 1, a base layer (width 238 mm, inner peripheral length 376 mm, thickness 120 μm, surface resistivity 1 × 10 ¹⁰ Ω / □, volume resistivity 6 × 10 ⁸ Ω · cm) was obtained.
Thereafter, the outer peripheral surface of the base layer was subjected to corona treatment at 30 W · min / m ² using a high-frequency power source AGF-A60 manufactured by Kasuga Electric Co., Ltd. and an aluminum electrode (effective length: 300 mm).
Next, a polyamideimide resin composed of 1 mol of trimellitic anhydride, 0.7 mol of 4,4′-diphenylmethane diisocyanate, and 0.3 mol of 2,4-tolylene diisocyanate is converted into N, N-dimethylacetamide (DMAc). It was made to melt | dissolve so that it might become 12 mass% of solid content, and the varnish E was obtained.
After the surface-treated base layer (width 238 mm, inner peripheral length 376 mm, thickness 120 μm, surface resistivity 1 × 10 ¹⁰ Ω / □) obtained above was mounted on a metal mandrel, the varnish E was coated with the varnish E. A mandrel with a base layer is immersed in a bath filled with the substrate vertically, the pulling speed is adjusted so that a surface layer having a thickness of 0.6 μm can be formed, and then dried in an oven. A conductive endless belt having the structure shown was produced.
The conductive endless belt produced above had a thickness of 120.6 μm, a surface resistivity of 2 × 10 ¹⁰ Ω / □, and a volume resistivity of 2 × 10 ⁹ Ω · cm.

Comparative Example 1
In Example 1 described above, without forming a surface layer, a single-layer conductivity having a width of 238 mm, an inner peripheral length of 376 mm, a thickness of 120 μm, a surface resistivity of 1 × 10 ¹⁰ Ω / □, and a volume resistivity of 6 × 10 ⁸ Ω · cm Created an endless belt.

Comparative Example 2
In Example 2 described above, without forming a surface layer, a single-layer conductivity having a width of 238 mm, an inner peripheral length of 376 mm, a thickness of 120 μm, a surface resistivity of 1 × 10 ¹⁰ Ω / □, and a volume resistivity of 6 × 10 ⁸ Ω · cm Created an endless belt.

Comparative Example 3
An acrylic resin (Clear SD-T-9559, manufactured by Resino Color Industry Co., Ltd.) was dissolved in isopropanol (IPA) so as to have a solid content concentration of 15% by mass, and varnish G was obtained.
The varnish G was treated with the corona surface-treated base layer obtained in Example 1 (width 238 mm, inner peripheral length 376 mm, thickness 120 μm, surface resistivity 1 × 10 ¹⁰ Ω / □, volume resistivity 6 × 10 ⁸ Ω · cm) on a metal mandrel, and then a bath filled with varnish G soaks the mandrel with the base layer on it perpendicular to the bath, so that a surface layer having a thickness of 0.8 μm can be formed. After adjusting the above, it was dried in an oven to produce a conductive endless belt having the structure shown in FIG.
The conductive endless belt produced above had a thickness of 120.8 μm, a surface resistivity of 2 × 10 ¹⁰ Ω / □, and a volume resistivity of 2 × 10 ⁹ Ω · cm.

Comparative Example 4
Polyamideimide resin composed of 1 mol of trimellitic anhydride, 0.7 mol of 4,4′-diphenylmethane diisocyanate and 0.3 mol of 2,4-tolylene diisocyanate is added to N, N-dimethylacetamide (DMAc) at a solid content concentration. After being dissolved so as to be 15% by mass, carbon black (Special Black 4, manufactured by Tegusa Japan) and DMAc are added so as to be 16 parts with respect to the solid content of the polyamideimide resin, and carbon black using a ball mill. Was uniformly dispersed to obtain a solid concentration of 18% by mass, and varnish H was obtained.
The entire amount of the varnish H was injected into the inner surface of a metal rotating drum (width 400 mm, inner diameter 120 mm; having a frame with a width of 20 mm on both sides) having a mirror-finished inner surface while slowly rotating. The rotation was gradually increased, and finally the rotation was continued at 340 times / minute for 30 minutes. While maintaining this state, the drum was heated to reach 200 ° C., and further rotated at that temperature for 120 minutes to evaporate the solvent and dry. Thereafter, the belt is taken out and the width is cut, so that the inner circumference length is 376 mm, the thickness is 80 μm, the surface resistivity is 1 × 10 ¹⁰ Ω / □, the volume resistivity is 9 × 10 ⁸ Ω · cm, and the width is 238 mm. A conductive belt was obtained.

Comparative Example 5
90% by weight of polyester (PET E-02, manufactured by Bell Polyester Products Co., Ltd.) and 10% by weight of carbon black (manufactured by Ketjen Black, Ketjen Black International Co., Ltd.) were mixed and put into a twin screw extruder. (Cylinder temperature 145-200 degreeC) and the pellet-shaped raw material I were produced.
The pellet-shaped raw material I was subjected to a circular mandrel die using a φ50 mm single screw extruder (cylinder temperature: 145 to 200 ° C.), an inner peripheral length of 376 mm, a thickness of 120 ± 7 μm, a width of 238 mm, and a surface resistivity of 1 × 10 ^10. A cylindrical tube (base layer) having an Ω / □ and volume resistivity of 6 × 10 ⁸ Ω · cm was formed.
Thereafter, the outer peripheral surface of the base layer was subjected to corona treatment at 30 W · min / m ² using a high-frequency power source AGF-A60 manufactured by Kasuga Electric Co., Ltd. and an aluminum electrode (effective length: 300 mm).
Next, the surface-treated base layer (width 238 mm, inner peripheral length 376 mm, thickness 120 μm, surface resistivity 1 × 10 ¹⁰ Ω / □) obtained above was applied to the varnish C obtained in the same manner as in Example 3. After covering the metal mandrel, the mandrel with the base layer was immersed perpendicularly to the bath in a bath filled with varnish C, and the pulling speed was adjusted so that a surface layer with a thickness of 0.8 μm could be formed. Thereafter, it was dried in an oven to produce a conductive endless belt having the structure shown in FIG.
The conductive endless belt produced above had a thickness of 120.8 μm, a surface resistivity of 3 × 10 ¹⁰ Ω / □, and a volume resistivity of 3 × 10 ⁹ Ω · cm.

Test example 1
The tensile elastic modulus and tensile elongation at break of each conductive endless belt surface layer and base layer alone were measured according to the above methods, and the results are shown in Table 1. Further, the thickness of the surface layer and the bending resistance of the belt were also measured in accordance with the above-described method.

Test example 2
Using each conductive endless belt as an intermediate transfer belt, the bleed-out property, filming resistance, and durability were confirmed according to the above-mentioned methods, and the results are shown in Table 1. Further, the glossiness and surface roughness of the surface layer, and the wear amount of the conductive endless belt were also measured in accordance with the above method, and the results are shown in Table 1.

  From the results of Examples 1 to 5, the conductive endless belt of the present invention having a base layer containing a polyamide resin and a surface layer containing an aromatic polyimide resin has excellent filming resistance and a small amount of wear. Excellent durability.

  Further, when a filler is added to the base layer of the present invention, although the tensile elongation at break is slightly reduced, it does not affect the durability, but rather, it is confirmed that the tensile elasticity is improved, thereby improving the creep property. It was.

  Further, from the results of Examples 1, 4 and 5, it was confirmed that when the thickness of the surface layer was increased, the glossiness of the surface layer was improved and the surface roughness was reduced.

  On the other hand, in the case of a single-layer belt made of only a base layer material without providing a surface layer, the filming resistance is poor (Example 1, Comparative Example 1, Example 2, and Comparative Example 2).

  Further, in the case of a single layer belt made of only a surface layer material without providing a base layer, there is no durability (Comparative Example 4).

  Furthermore, in the case where the surface layer is an acrylic resin as disclosed in the prior art, there is a problem that bleeding out easily occurs (Comparative Example 3).

  And when the base layer is PET as disclosed in the prior art, the bending resistance is inferior (Comparative Example 5).

1 base layer 11 surface layer

Claims (12)

A base layer comprising a polyamide resin, possess a surface layer comprising an aromatic polyimide resin, conductive endless belt the aromatic polyimide resin is a polyamide-imide resin. The conductive endless belt according to claim 1, wherein the base layer contains an inorganic filler. Said surface layer is a thick 0.5～1.3Myuemu, conductive endless belt according to claim 1 or 2. The conductive endless belt according to any one of claims 1 to 3 , wherein the surface layer has a surface roughness (Rz) of less than 1.0 µm. It glossiness of 70 or more at 60 ° incidence angle of the surface layer, electroconductive endless belt according to any one of claims 1-4. The conductive endless belt according to any one of claims 1 to 5 , wherein the surface layer is formed by coating. Surface resistivity of ^{1 × 10 6 Ω / □ ~1} × 10 14 Ω / □, conductive endless belt according to any one of claims 1-6. Volume resistivity is ^{1 × 10 4 Ω · cm~1 ×} 10 14 Ω · cm, conductive endless belt according to any one of claims 1-7. The conductive endless belt according to any one of claims 1 to 8 , which is an intermediate transfer belt in a color image forming apparatus. A process for producing a conductive endless belt, comprising a base layer containing a polyamide resin and a surface layer containing an aromatic polyimide resin, comprising the following steps (1) and (2)
(1) a step of forming a base layer by extruding a base layer forming composition containing a polyamide resin and a conductive agent, and if necessary an inorganic filler, and (2) a surface layer forming composition containing an aromatic polyimide resin, The process of laminating | stacking on the outer surface of the base layer obtained by said (1), and forming a surface layer. The manufacturing method according to claim 10 , wherein in the step (2), the surface layer is formed by dissolving the aromatic polyimide resin in a solvent and coating the surface layer forming composition on the outer surface of the base layer. A method for producing a conductive endless belt having a base layer containing a polyamide resin and a surface layer containing an aromatic polyimide resin, including the following steps (1) to (3);
(1) A step of forming a base layer by extruding a base layer forming composition containing a polyamide resin and a conductive agent, and if necessary, an inorganic filler;
(2) A step of forming a surface layer by centrifugally forming a surface layer-forming composition containing an aromatic polyimide resin using a cylindrical mold, and (3) on the inner surface of the surface layer obtained in (2) above The process of heat-treating the outer surface of the base layer obtained in (1) above.

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