JP2010208803A - Carrier belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a carrier belt superior in both attraction performance and separation performance of paper, superior in paper feeding accuracy, and superior in cleaning performance, stain resistance and durability. <P>SOLUTION: This carrier belt has an inner layer including a polyimide resin including a conductive substance and an outer layer. In the carrier belt, surface resistivity of the outer layer is higher by one digit or more than surface resistivity of the inner layer, and volume resistivity of the whole carrier belt is a common logarithm value 7-12 (logΩcm). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a conveyor belt.

  Since a high temperature and pressure are applied to the conveying belt used in the image forming apparatus, heat resistance and high mechanical strength are required. For this reason, a polyimide resin is preferably used as a material for the conveying belt. For example, a conveying belt formed by forming a polyimide resin into a film and joining it into a tubular shape has been proposed (Patent Document 1). However, in the case of such a conveyor belt, when it is used for a long time, peeling or the like occurs in the film joining portion, and the durability is low, and the low joining accuracy greatly affects the circumference accuracy of the conveying belt. The problem of meandering is likely to occur. In addition, it has a structure having two layers of an insulating layer (outer layer) made of a resin such as ethylenetetrafluoroethylene copolymer (ETFE) and a conductive layer (inner layer) containing carbon in a resin such as ETFE. A conveying belt that electrostatically adsorbs a recording medium (paper) in a stable manner is disclosed (Patent Document 2). However, the conveyor belt has a problem that the discharge product adheres to the discharge belt due to a discharge phenomenon or is soiled by paper dust, and the cleaning property is poor.

JP 11-291348 A JP 2003-103857 A

  The present invention has been made in order to solve the above-described conventional problems. The object of the present invention is to improve both paper adsorbability and peelability, excellent paper feeding accuracy, and cleanability, stain resistance, and the like. An object of the present invention is to provide a conveyor belt having good durability.

The conveying belt of the present invention includes an inner layer containing a polyimide resin containing a conductive substance, and an outer layer whose surface resistivity is one digit or more higher than the surface resistivity of the inner layer, and the overall volume resistivity is a common logarithm value of 7 To 12 (log Ω · cm).
In preferable embodiment, the content rate of the electroconductive substance of the said inner layer is 3-40 parts with respect to 100 parts of polyimide resins.
In a preferred embodiment, the surface resistivity of the inner layer is a common logarithmic value of 6 to 13 (log Ω / □).
In a preferred embodiment, the outer layer contains a fluororesin.
In a preferred embodiment, the outer layer includes silicone rubber.
In a preferred embodiment, the outer layer contains a conductive substance, and the content ratio of the conductive material is 0.5 to 2.0% by weight with respect to the total weight of the outer layer.
In a preferred embodiment, the outer layer contains a conductive substance, and the content ratio of the conductive material is 30.0% by weight or less based on the total weight of the outer layer.
In a preferred embodiment, the outer layer has a surface roughness Rz of 5 μm or less.
In a preferred embodiment, the pure water contact angle of the outer layer surface is 90 degrees or more.

  According to the present invention, it is possible to obtain a conveying belt having excellent paper adsorbability and peelability, and excellent cleaning properties, stain resistance and durability. Since the conveyance belt of the present invention exhibits good paper adsorption and peelability, the paper feeding accuracy is high. In addition, excellent stain resistance and cleaning properties make it difficult for ink stains to adhere and contribute to good image formation. Furthermore, since the conveyance belt of the present invention is a tubular body that does not have a joint (joint formed when the film is formed into a tube), it contributes to excellent image formation with excellent circumferential length accuracy and durability. Also excellent.

It is a schematic sectional drawing of the belt for conveyance in preferable embodiment of this invention.

A. Overall Constitution of Conveying Belt The conveying belt of the present invention preferably conveys a recording medium in the image forming apparatus. The recording medium is typically paper.

  FIG. 1 is a schematic sectional view of a conveying belt according to a preferred embodiment of the present invention. The conveyor belt 10 includes an inner layer 1 and an outer layer 2. The inner layer 1 includes a polyimide resin containing a conductive substance. The outer layer 2 preferably contains a fluororesin or silicone rubber. In the present specification, the “outer layer” is a layer that forms the outermost periphery of the conveyance belt, and refers to a layer on the side on which the paper is conveyed. Further, in this specification, the “inner layer” is a layer that does not come into contact with paper in the transport belt, and refers to a layer that comes into contact with a roll for driving the transport belt, for example.

  The surface resistivity of the outer layer is one digit or more higher than the surface resistivity of the inner layer, preferably two digits or more. Thus, by adjusting the surface resistivity of the outer layer and the inner layer, appropriate electrostatic adsorption can be obtained, and accumulation of residual charges due to continuous use during charging can be prevented. As a result, it is possible to obtain a conveyance belt that can stably achieve both paper adsorbability and peelability and is excellent in cleaning properties and stain resistance. In one embodiment, the outer layer surface resistivity is equal to or greater than the common logarithmic value of 14 (log Ω / □), and the inner layer has a surface resistivity of 6 to 13 (log Ω / □). In another embodiment, the surface resistivity of the outer layer is a common logarithmic value of 10-14 (log Ω / □) and the surface resistivity of the inner layer is a common logarithmic value of 6-8 (log Ω / □). The surface resistivity of the outer layer and the inner layer can be controlled by adjusting the type and content of the conductive substance contained in the outer layer and the inner layer.

  The volume resistivity of the entire conveying belt of the present invention is a common logarithmic value of 7 to 12 (log Ω · cm), more preferably a common logarithmic value of 8 to 10 (log Ω · cm). If the volume resistivity of the transport belt is within this range, the transport performance is excellent in both sheet adsorbability and releasability, suppression of transport belt speed fluctuation, transport belt charge uniformity, and peel discharge performance. Belts can be obtained. The volume resistivity of the entire conveyance belt can be controlled by adjusting the type and content of the conductive material contained in the outer layer and the inner layer.

  As long as the effect of the present invention is obtained, the transport belt of the present invention may further include any appropriate intermediate layer between the outer layer and the inner layer.

B. Inner layer As described above, the inner layer includes a polyimide resin containing a conductive substance.

  Any appropriate resin can be adopted as the polyimide resin. Examples of the polyimide resin include a copolymer of tetracarboxylic dianhydride or a derivative thereof and a diamine compound.

  Specific examples of the tetracarboxylic dianhydride include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetra Carboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalene Tetracarboxylic dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,2′-bis (3,4 Dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ) Ete Dianhydride, ethylene tetracarboxylic dianhydride, and the like.

  Specific examples of the diamine compound include p-phenylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4 ′. -Diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-phenylenediamine, 3,3'-dimethyl-4,4'-biphenyldiamine, benzidine, 3,3'-dimethylbenzidine 3,3′-dimethoxybenzidine, 4,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenylpropane, 2,4-bis (β-amino-t-butyl) Toluene, bis (p-β-amino-t-butylphenyl) ether Bis (p-β-methyl-δ-aminophenyl) benzene, bis-p- (1,1-dimethyl-5-amino-pentyl) benzene, 1-isopropyl-2,4-m-phenylenediamine, m- Xylylenediamine, p-xylylenediamine, di (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, diaminopropyltetramethylene, 3-methylheptamethylene Diamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethyl To heptamethylenediamine, 3-methyl Ptamethylenediamine, 5-methylnonamethylenediamine, 2,11-diaminododecane, 2,17-diaminoeicosadecane, 1,4-diaminocyclohexane, 1,10-diamino-1,10-dimethyldecane, 1,12 -Diaminooctadecane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane and the like.

  The polyimide resin is preferably an aromatic polyimide resin. If an aromatic polyimide resin is used, it is possible to obtain a transport belt having better heat resistance and mechanical strength. Specific examples of the aromatic polyimide resin include a copolymer of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-diaminodiphenyl ether (DDE), BPDA, and DDE. And a copolymer of p-phenylenediamine (PDA). The content ratio of the structural unit derived from PDA in the copolymer of BPDA, DDE and PDA is preferably 25 mol% or less with respect to the structural unit derived from DDE.

  Any appropriate material can be adopted as the conductive material. Specific examples of the conductive material include carbon black such as ketjen black and graft carbon; various metals such as aluminum, silver and copper. Carbon black is preferable.

Any appropriate carbon black may be adopted depending on the desired conductivity. Specific examples of the carbon black include channel black, furnace black, ketjen black, and acetylene black. When antistatic properties are required in the middle to high resistance range (for example, surface resistivity 10 ⁸ to 10 ¹⁴ Ω / □, volume resistivity 10 ⁸ to 10 ¹⁴ Ω · cm), channel black or furnace black Are preferably used. The carbon black may be subjected to a treatment such as an oxidation treatment or a graft treatment depending on the application. If oxidation treatment is performed, oxidative deterioration can be prevented, and if graft treatment is performed, dispersibility in a solvent can be improved.

  A commercial product may be used as the carbon black. As specific examples of commercially available channel black, trade names “Color Black FW200”, “Color Black FW2”, “Color Black FW2V”, “Color Black FW1”, “Color Black FW18”, “Sp Black” FW18, “Sp”, manufactured by Degussa Huls, Inc. Black 6 ”,“ Color Black S170 ”,“ Color Black S160 ”,“ Special Black 5 ”,“ Special Black 4 ”,“ Special Black 4A ”,“ Printex 150T ”,“ Print V ”,“ PrintV ” Printex 140U "," Printex 140V ", etc. are mentioned. As specific examples of commercially available furnace black, trade names “Special Black 550”, “Special Black 350”, “Special Black 250”, “Special Black 100”, “Printex 35”, and “Printex 35” manufactured by Degussa Huls. “25”, trade names “MA 7”, “MA 77”, “MA 8”, “MA 11”, “MA 100”, “MA 100R”, “MA 220”, “MA 230”, manufactured by Mitsubishi Chemical Corporation, “MONARCH 1300”, “MONARCH 1100”, “MONARCH 1000”, “MONARCH 900”, “MONARCH 880”, “MONARCH 800”, “MONARCH 700”, “MOGUL L”, “REG” manufactured by Cabot Corporation AL 400R "," VULCAN XC-72R "and the like.

  The content of the conductive material is preferably 3 to 40 parts, more preferably 3 to 30 parts, relative to 100 parts of the polyimide resin. When the content of the conductive material is within such a range, a transport belt that can obtain desired surface resistivity and volume resistivity for the inner layer and the entire transport belt and that has excellent mechanical strength is provided. Obtainable.

  The thickness of the inner layer is preferably 20 to 150 μm, more preferably 50 to 100 μm.

  The surface resistivity of the inner layer is preferably a common logarithmic value of 6 to 13 (log Ω / □), and more preferably 6 to 12 (log Ω / □). If the surface resistivity of the inner layer is in such a range, accumulation of residual charges due to continuous use during charging can be prevented. As a result, it is possible to obtain a conveying belt that can stably achieve both the adsorptivity and the peelability of the paper and is excellent in cleaning properties and stain resistance. The surface resistivity of the inner layer can be adjusted by the type and content of the conductive substance.

  The inner layer (1) disperses the conductive substance in an organic polar solvent to prepare a conductive substance dispersion, and (2) the tetracarboxylic dianhydride or derivative thereof is added to the conductive substance dispersion. After dissolving the diamine compound, a polymerization reaction is carried out to prepare a conductive material-dispersed polyamic acid solution. (3) The ring-closing imidization reaction proceeds after the conductive material-dispersed polyamic acid solution is developed in a cylindrical mold. Thus, it can be obtained by forming a polyimide resin containing a conductive substance into a tubular shape.

  Any appropriate solvent can be adopted as the organic polar solvent as long as the conductive substance can be dispersed. Specific examples of the organic polar solvent include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, hexa Examples include methyl phosphortriamide, N-methyl-2-pyrrolidone, pyridine, tetramethylene sulfone, dimethyltetramethylene sulfone and the like. Of these, N, N-dialkylamides such as N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, and N, N-diethylacetamide are preferable. In the case of N, N-dialkylamides, the dispersion solvent of the conductive substance and the polymerization reaction solvent in the subsequent step can be used together. In addition, low molecular weight N, N-dimethylformamide and N, N-dimethylacetamide can be easily removed from the polyamic acid and the polyamic acid molded article by evaporation, substitution or diffusion. The said organic polar solvent may be used independently and may be used in combination of 2 or more type.

  The organic polar solvent may be mixed with phenols such as cresol, phenol, xylenol, benzonitrile, dioxane, butyrolactone, xylene, cyclohexane, hexane, benzene, toluene, etc. alone or in combination.

  The conductive material dispersion may further contain a dispersant. If the conductive material contains a dispersant, the affinity between the conductive material and the organic polar solvent can be increased. Any appropriate dispersant can be adopted as the dispersant as long as the effects of the present invention can be obtained. Specific examples of the dispersant include poly (N-vinyl-2-pyrrolidone), poly (N, N′-diethylacrylazide), poly (N-vinylformamide), poly (N-vinylacetamide), poly (N N-vinylphthalamide), poly (N-vinylsuccinamide), poly (N-vinylurea), poly (N-vinylpiperidone), poly (N-vinylcaprolactam), poly (N-vinyloxazoline), etc. Polymer dispersing agent; Surfactant, inorganic salt and the like. These dispersants may be used alone or in combination of two or more.

  Any appropriate dispersion method can be applied to the conductive material dispersion method. Examples of the dispersion method include a ball mill, a sand mill, a basket mill, a three-roll mill, a planetary mixer, a bead mill, and an ultrasonic dispersion method. The method for examining the dispersion state of the conductive substance is not particularly limited, and examples thereof include a method of observing with an optical microscope.

  The tetracarboxylic dianhydride or its derivative and a diamine compound are dissolved in the conductive substance dispersion, and then polymerized to obtain a conductive substance-dispersed polyamic acid solution. During the polymerization, a catalyst is preferably added. Any appropriate catalyst can be adopted as the catalyst. Specific examples of the catalyst include aliphatic tertiary amines, aromatic tertiary amines, and heterocyclic tertiary amines. Of these, nitrogen-containing heterocyclic compounds such as imidazole, benzimidazole, isoquinoline, quinoline, diethylpyridine, and β-picoline are preferred.

  The usage-amount of the said catalyst is 0.04-0.4 molar equivalent with respect to 1 molar equivalent of amic acid of a polyamic-acid precursor solution, Preferably it is 0.05-0.4 molar equivalent. When the addition amount of the catalyst is 0.04 equivalent mole or less, the effect of the catalyst is not sufficient, and even when 0.4 equivalent or more is added, the effect is not improved.

  The monomer concentration (concentration of tetracarboxylic dianhydride component and diamine component in the solvent) during the polymerization reaction is preferably 5 to 30% by weight.

  The reaction temperature during the polymerization reaction is preferably 80 ° C. or lower, and more preferably 5 to 50 ° C. The reaction time is preferably 5 to 10 hours.

  The solution viscosity of the conductive substance-dispersed polyamic acid solution is preferably 1 to 1000 Pa · s (25 ° C.) with a B-type viscometer. If the solution viscosity is in such a range, the solution can be uniformly developed at the time of centrifugal molding in the next step, and a transport belt having a uniform thickness can be obtained. The solution viscosity of the conductive material-dispersed polyamic acid solution can be set to a desired viscosity by further heating and stirring the conductive material-dispersed polyamic acid solution obtained after the polymerization reaction. The heating temperature is preferably 50 to 90 ° C.

  After the conductive substance-dispersed polyamic acid solution is developed in a cylindrical mold, a ring-closing imidization reaction is advanced to form a polyimide resin containing a conductive substance in a tubular shape. By forming a polyimide resin containing a conductive substance into a tubular shape, an inner layer of a transport belt that does not have a joint (a joint produced when the film is tubular) can be obtained. As a result, it is possible to obtain a conveyor belt that is excellent in durability and circumference accuracy. Examples of the method of developing the cylindrical mold include a method of developing the inner peripheral surface of the mold by centrifugal force by a rotary centrifugal molding method. According to such a method, the conductive material-dispersed polyamic acid solution can be uniformly developed. The ring-opening imidization reaction can proceed by heating the developed conductive material-dispersed polyamic acid solution. The heating temperature at this time is preferably 300 to 450 ° C. The heating method is preferably a method of heating while rotating the mold, a method of using high-precision hot air circulation, a method of charging at a low temperature to reduce the temperature rising rate, and a combination of these methods. According to such a heating method, the conductive material-dispersed polyamic acid solution and the dried product thereof can be heated uniformly, and aggregation of the conductive material can be suppressed. As a result, the surface resistivity of the inner layer and the volume resistivity of the entire conveyor belt can be made uniform.

C. Intermediate Layer The transport belt of the present invention may have any appropriate intermediate layer between the inner layer and the outer layer as necessary. Examples of the intermediate layer include a conductive primer layer. If the conductive primer layer is provided as the intermediate layer, the adhesion between the outer layer and the inner layer can be improved. Examples of the conductive primer include a conductive fluorine-based primer and a conductive polyimide-based primer.

  The thickness of the intermediate layer is preferably 0.3 to 5 μm, more preferably 0.5 to 2 μm.

  The intermediate layer can be formed by any appropriate method. For example, when the intermediate layer is a conductive primer layer, it can be obtained by applying a primer solution to the outer peripheral surface of the inner layer. Examples of the application method include roll coating, brush coating, and spray coating.

D. Outer layer

  As described above, the outer layer preferably contains a fluororesin or silicone rubber.

  Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). Of these, PFA is preferable. If the outer layer contains a fluororesin, it is excellent in releasability, so that it is possible to obtain a conveying belt that is excellent in stain resistance, cleaning properties, and separation of conveyed paper. In particular, if the fluororesin is PFA, it is possible to obtain a transport belt that is extremely excellent in releasability. The said fluororesin may be used independently and may be used in combination of 2 or more type.

  The content of the fluororesin is preferably 50 to 100% by weight, more preferably 80 to 100% by weight, based on the total weight of the outer layer.

  The silicone rubber is preferably a liquid silicone rubber. Specific examples of the silicone rubber include thermosetting silicone rubber (silicone RTV rubber). If the outer layer contains silicone rubber, it has high elasticity, so that it is possible to obtain a transport belt without paper misalignment when transporting paper. The said silicone rubber may be used individually and may be used in combination of 2 or more type.

  The content ratio of the silicone rubber is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, still more preferably 80 to 100% by weight, based on the total weight of the outer layer.

  The outer layer may contain a conductive substance according to the purpose, desired conductivity, the type of material forming the outer layer, and the like. As the conductive substance, for example, a conductive substance used for the inner layer can be used. Carbon black is preferable, and Ketjen black having high conductivity is particularly preferable. Note that depending on the material forming the outer layer, the outer layer may not include the conductive substance.

  When the outer layer containing the fluororesin contains the conductive substance, the content of the conductive substance is preferably 2.0% by weight or less, more preferably 0.5 to less than the total weight of the outer layer. The amount is 2.0% by weight, particularly preferably 1.0 to 1.5% by weight. If the content of the conductive material is less than 0.5% by weight, the desired surface resistivity may not be obtained. If the content is more than 2.0% by weight, sufficient releasability and wear resistance are obtained. There is a risk of not being able to.

  When the outer layer containing the silicone rubber contains the conductive material, the content of the conductive material is preferably 30% by weight or less based on the total weight of the outer layer. When the content of the conductive material is more than 30% by weight, there is a possibility that sufficient release properties and wear resistance cannot be obtained.

  The outer layer may further contain other forming materials. Examples of the other forming materials include rubber materials such as fluoro rubber, and heat-resistant elastic bodies such as various elastomers.

  The fluororubber is preferably liquid (including dispersion) fluororubber. Specific examples of the fluororubber include fluororubbers such as FKM (vinylidene fluoride-hexafluoropropylene copolymer (VDF-HFP) fluororubber two-dimensional and three-dimensional copolymers) latex. .

  Arbitrary appropriate thickness can be employ | adopted for the thickness of the said outer layer according to the material which forms an outer layer. For example, when the outer layer contains a fluororesin, the thickness of the outer layer is preferably 5 to 30 μm, more preferably 10 to 20 μm. Moreover, when an outer layer contains silicone rubber, the thickness of the said outer layer becomes like this. Preferably it is 10-700 micrometers, More preferably, it is 10-500 micrometers.

  The surface resistivity of the outer layer is preferably a common logarithmic value of 10 to 15 (log Ω / □), and more preferably 11 to 14 (log Ω / □).

  The surface roughness Rz of the outer layer is preferably 5 μm or less, more preferably 4 μm or less, and particularly preferably 2 to 4 μm. When the surface roughness Rz of the outer layer is in such a range, a conveying belt having excellent cleaning properties and stain resistance can be obtained. Further, since the surface releasability is maintained even after cleaning with a blade or the like, the cleaning property and stain resistance can be maintained over a long period of time, and the gloss of the surface of the conveying belt is also maintained.

  The pure water contact angle on the surface of the outer layer is preferably 90 degrees or more, more preferably 95 degrees or more, and particularly preferably 95 to 120 degrees. If the pure water contact angle on the surface of the outer layer is within such a range, it is possible to obtain a transport belt having excellent cleaning properties and stain resistance. Further, since the surface releasability is maintained even after cleaning with a blade or the like, the cleaning property and stain resistance can be maintained over a long period of time, and the gloss of the surface of the conveying belt is also maintained.

  Examples of the method for forming the outer layer include a method in which a tubular body containing a fluororesin or silicone rubber obtained by melt extrusion is applied to the outer surface of the inner layer, or a liquid fluororesin or silicone rubber solution is coated on the outer surface of the inner layer. Methods and the like. If the outer layer is formed by such a method, it is possible to obtain the outer layer of the belt for conveyance that does not have a joint (joint formed when the film is tubular). As a result, it is possible to obtain a conveyor belt that is excellent in durability and circumference accuracy. In the present specification, the liquid fluororesin includes a dispersion form.

  The method for coating the outer surface of the inner layer with the liquid fluororesin or silicone rubber preferably includes a step of applying the liquid fluororesin or silicone rubber to the outer surface of the inner layer and a step of drying and heating after the coating.

  Examples of the method for applying the liquid fluororesin or silicone rubber include spray coating, spin coating, roll coating, brush coating, and the like.

As the gun used for the spray coating, a gun having a small nozzle diameter is preferable because uniform application is possible. The nozzle diameter is usually 0.1 to 2.0 mm. The spray pressure during the spray coating is preferably 1.0 to 5.0 kg / cm ² .

  When applying the liquid fluororesin or silicone rubber, a cylinder for maintaining the shape may be fitted inside the inner layer. Further, a cylindrical body is extrapolated to the inner layer coated with the liquid fluororesin or silicone rubber, and from this state, the cylindrical body or the inner layer is run in the axial direction of the cylindrical body, or the two are mutually connected. You may make it run in an opposite direction and make application | coating thickness uniform.

  The drying temperature after applying the liquid fluororesin is preferably 80 to 150 ° C, more preferably 90 to 130 ° C. The drying time during the drying is preferably 10 to 30 minutes. After removing the solvent in the liquid fluororesin by the drying, an outer layer containing the fluororesin is formed on the outer surface of the inner layer (or on the outer surface of the intermediate layer) by further heating at a melting point or higher of the fluororesin. it can. Any appropriate temperature can be adopted as the heating temperature depending on the type of the fluororesin. Typically, it is 200 to 350 ° C. The heating time is preferably 1 to 60 minutes. In this way, generation of voids can be prevented by raising the temperature stepwise by separating drying and heating. In addition, you may perform the ring-opening imide reaction of the said inner layer simultaneously at the said heating.

  The heating temperature after applying the liquid silicone rubber is preferably 20 to 150 ° C, more preferably 90 to 130 ° C. The heating time during the heating is preferably 1 to 24 hours. By heating under such conditions, the silicone rubber can be cured to form an outer layer containing silicone rubber on the outer surface of the inner layer (or on the surface of the intermediate layer).

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples at all. In addition, the test and evaluation method in an Example etc. are as follows.

[Surface resistivity, volume resistivity]
UP MCP-HT450 (manufactured by Mitsubishi Chemical Corporation, probe: UR) is used as the Hiresta, and the applied voltage is 500V (note that the measured value is lower than the common logarithmic value of 8.0 or lower, so the voltage is lowered and measured at the applied voltage of 10V), The surface resistivity and volume resistivity at 25 ° C. and 60% RH were measured under the measurement conditions for 10 seconds. The measurement was performed at 8 points on the surface of the conveyor belt, and the average value was expressed as a common logarithmic value [surface roughness Rz].
In accordance with JIS 1994, samples were taken from any five points on the surface of the conveyor belt, and with respect to the circumferential direction, a cut-off value of 0.8 mm and a measurement length were measured with a surface roughness meter (Surfcom SJ301, manufactured by Tokyo Seimitsu Co., Ltd.). Measurement was performed at 2.5 mm and a driving speed of 0.25 mm / sec.
[Pure water contact angle]
The contact angle of pure water was measured with an automatic contact angle measuring apparatus (manufactured by Eiko Seiki Co., Ltd., SCA20).
[Paper adsorption]
The transport belt obtained in the Examples and the like is mounted on a roll as a paper transport belt for an ink jet printer, mounted on a roll, using color ink and A4 size paper as a recording sheet, room temperature, humidity 50% Printing was carried out for 12 hours in an Rh environment to evaluate paper adsorption.
○ ・ ・ ・ Paper is adsorbed on the conveyor belt and can be printed without any problems.
× ・ ・ ・ Paper is not adsorbed on the conveyor belt, causing problems [stain resistance]
The conveyor belt obtained in the examples and the like is mounted on a roll as a paper conveyor belt for an ink jet printer, and is used with color ink and A4 size paper as a recording sheet, at room temperature and humidity of 50% Rh. The appearance of the conveyor belt after printing for 12 hours under the environment was visually confirmed to evaluate the stain resistance.
○ ・ ・ ・ Contamination does not adhere to the surface of the conveyor belt, and the conveyed paper is not contaminated. △ ・ ・ ・ Contamination on the surface of the conveyor belt is not visually confirmed, but the conveyed paper is slightly soiled. Dirt adheres to the belt surface and the transported paper gets dirty.

<Example 1>
(Formation of semiconductive polyimide resin tubular body (inner layer))
317.5 g of carbon black (manufactured by Degussa Japan, special black 4) was added to 1800 g of N-methyl-2-pyrrolidone (NMP).
After being dispersed by stirring at room temperature for 12 hours with a ball mill, it was filtered through a # 400 stainless steel mesh to obtain a carbon dispersion having a concentration of 15% by weight.
1050.7 g of this carbon dispersion was transferred to a 5000 mL four-necked flask, charged with 2669.5 g of N-methyl-2-pyrrolidone, 96.1 g of p-phenylenediamine, and 177.9 g of 4,4′-diaminodiphenyl ether. And dissolved with stirring.
Next, 523.1 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was added and reacted at a temperature of 25 ° C. for 1 hour, followed by stirring while heating at 75 ° C. for 20 hours. A carbon black-containing polyimide precursor solution (solid content concentration 20 wt%, carbon black addition amount: 21.5 wt% with respect to the resin) having a solution viscosity of 182 Pa · s as measured by a B-type viscometer was obtained. The carbon black-containing polyimide precursor solution was filtered using a # 800 stainless steel mesh to obtain a semiconductive polyimide resin tubular body forming material.
Next, a semiconductive polyimide resin tubular body forming material was applied to the inner peripheral surface of a cylindrical cylinder having a diameter of 120 mm and a length of 500 mm so as to have a thickness of 600 μm. It was rotated for a minute to obtain a spread layer having a uniform thickness. Thereafter, hot air at 130 ° C. was blown from the outside of the cylindrical cylinder for 30 minutes while rotating the cylindrical cylinder at 250 rpm, and then the temperature was raised to 370 ° C. at a rate of 20 ° C./minute and heated at that temperature for 30 minutes. After cooling. Thereafter, the tubular film formed on the inner peripheral surface of the cylindrical cylinder was peeled off to obtain a 75 μm semiconductive polyimide resin tubular body.
(Formation of primer layer (intermediate layer))
The outer surface of the semiconductive polyimide resin tubular body thus obtained is uniformly coated with polyimide primer K-001 (Mitsui / DuPont / Fluorochemical) and air-dried at 150 ° C. for 10 minutes to conduct electricity. A primer layer was formed. The thickness of the conductive primer layer was 1 μm.
(Formation of outer layer)
An aqueous dispersion having a PFA concentration of 60% by weight (manufactured by DuPont, TE-334J) was uniformly spray-coated on the outer peripheral surface (primer layer surface) of the inner layer on which the primer layer was formed, and air-dried for 10 minutes.
Thereafter, the dispersion medium water was evaporated and removed by heating at 100 ° C. for 10 minutes, and further heated at 400 ° C. for 5 minutes as a full cure, and the temperature was lowered to room temperature over 270 minutes to obtain an outer layer containing PFA. The thickness of the outer layer was 15 μm.
As a result, three layers comprising an inner layer made of polyimide resin containing a conductive substance, a conductive primer layer formed on the outer peripheral surface of the inner layer, and an outer layer containing PFA sintered on the outer peripheral surface of the primer layer A transport belt having a structure was obtained.
(Characteristics of conveyor belt)
The surface resistivity of the outer layer of the obtained conveyance belt is not less than the common logarithm value of 14.0 (logΩ / □) at an applied voltage of 500 V, the surface resistivity of the inner layer is the common logarithm value of 10.56 (logΩ / □), The volume resistivity of the entire production belt was a common logarithmic value of 9.26 (log Ω · cm) at an applied voltage of 500V. The surface roughness Rz was 2.68 μm. The pure water contact angle was 108 °.
Further, both the paper adsorbing property and the stain resistance of the obtained conveying belt were good, and a good image was obtained.

<Example 2>
In place of 1050.7 g of carbon dispersion, 1124.0 g of carbon dispersion was used, and in place of 2669.5 g of N-methyl-2-pyrrolidone, 1124.0 g of N-methyl-2-pyrrolidone was used, and the PFA concentration was 60 wt. Example 1 except that an aqueous dispersion having a PFA concentration of 50% by weight, in which 1.0% by weight of carbon black having an average particle size of 0.3 μm was added to the PFA solid content, was used in place of the aqueous dispersion having a weight of 0.3%. A conveyor belt was obtained in the same manner as described above. At this time, the carbon black-containing polyimide precursor solution in forming the semiconductive polyimide resin tubular body (inner layer) has a solid content concentration of 20 wt%, and the added amount of carbon black is 23 wt% with respect to the resin. there were. The aqueous dispersion having a PFA concentration of 50% by weight was obtained by mixing and dispersing using a ball mill.
The surface resistivity of the outer layer of the resulting conveyor belt is a common logarithm value of 11.52 (logΩ / □) at an applied voltage of 500 V, and the surface resistivity of the inner layer is a common logarithm value of 6.54 (logΩ / □) at an applied voltage of 10 V. ), The volume resistivity of the entire conveying belt was a common logarithmic value of 8.34 (log Ω · cm) at an applied voltage of 500V. The surface roughness Rz was 3.23 μm. The pure water contact angle was 95 °.
Further, both the paper adsorbing property and the stain resistance of the obtained conveying belt were good, and a good image was obtained.

<Example 3>
A semiconductive polyimide resin tubular body produced in the same manner as in Example 1 (Formation of semiconductive polyimide resin tubular body (inner layer)) has an outer diameter of 120.92 mm, a wall thickness of 5 mm, and a length of 500 mm, and the outer peripheral surface is smoothly finished. It was inserted into the outer periphery of a stainless steel cylinder. Next, RTV silicone rubber (trade name “KE-1833” manufactured by Shin-Etsu Chemical Co., Ltd.) was applied to the outer peripheral surface of the semiconductive polyimide resin tubular body. At this time, along the outer peripheral surface of the conductive polyimide resin tubular body inserted into the cylinder, the cylindrical traveling body having an inner diameter of 120.3 mm is used to travel in the axial direction of the cylinder at a speed of 50 mm / min by the self-weight traveling method. I let you. Then, it heated for 10 minutes at the temperature of 120 degreeC, and also heated for 30 minutes at the temperature of 180 degreeC.
As a result, a transport belt having a two-layer structure in which a tubular body made of a conductive polyimide resin was used as an inner layer and a tubular outer layer made of silicone rubber was provided on the outer peripheral surface thereof was obtained.
The total thickness of the obtained conveyance belt was 375 μm, and the thickness of the tubular outer layer was 300 μm. Further, the surface resistivity of the outer layer of the obtained conveyor belt is not less than the common logarithm value of 14 (logΩ / □) at an applied voltage of 500 V, the surface resistivity of the inner layer is the common logarithm value of 10.88 (logΩ / □), The volume resistivity of the entire belt was a common logarithmic value of 11.24 (log Ω · cm) at an applied voltage of 500V. The surface roughness Rz was 3.45 μm. The pure water contact angle was 98 °.
Further, both the paper adsorbing property and the stain resistance of the obtained conveying belt were good, and a good image was obtained.

<Comparative Example 1>
Using the semiconductive polyimide resin tubular body formed in Example 2, a single-layer conveying belt was obtained.
The surface resistivity of the obtained conveyor belt is a common logarithm of 6.82 (logΩ / □) at an applied voltage of 10 V, and the volume resistivity of the entire conveyor belt is a common logarithm of 5 (logΩ · cm) at an applied voltage of 100 V. It was the following. The surface roughness Rz was 2.68 μm. The pure water contact angle was 95 °.
Further, the paper adsorbing property and the peelability at the time of transport of the obtained transport belt were not preferable in practice, and partial peeling and transport stability were insufficient. In addition, with respect to stain resistance, ink stains were observed on the entire surface of the conveying belt.

<Comparative example 2>
Instead of an aqueous dispersion having a PFA concentration of 50% by weight, in which 1.0% by weight of carbon black having an average particle diameter of 0.3 μm is added to the PFA solid content, carbon black having an average particle diameter of 0.3 μm is used as the PFA solid content. A conveyor belt was obtained in the same manner as in Example 2, except that an aqueous dispersion having a PFA concentration of 50% by weight added with 3.0% by weight was used.
The surface resistivity of the outer layer of the obtained transport belt is 7.24 (log Ω / □) of the common logarithm at an applied voltage of 10 V, the surface resistivity of the inner layer is 6.54 (log Ω / □), The volume resistivity was not more than the common logarithm value 5 (log Ω · cm) at an applied voltage of 10 V. The surface roughness Rz was 5.24 μm. The pure water contact angle was 84 °.
Further, the sheet adsorbing property and the peelability at the time of transport of the obtained transport belt were not preferable in practice, and the partial peeling and transport stability were insufficient. In addition, regarding stain resistance, ink stains were present on the entire surface of the conveying belt.

<Comparative Example 3>
Instead of the aqueous dispersion having a PFA concentration of 60% by weight, an aqueous dispersion having a PFA concentration of 50% by weight, in which 1.0% by weight of carbon black having an average particle size of 0.3 μm was added to the PFA solid content, was used. In the same manner as in Example 1, a conveying belt was obtained. The aqueous dispersion having a PFA concentration of 50% by weight was obtained by mixing and dispersing using a ball mill.
The surface resistivity of the outer layer of the resulting conveyor belt is a common logarithm value of 11.68 (logΩ / □) at an applied voltage of 500 V, and the surface resistivity of the inner layer is a common logarithm value of 10.85 (logΩ / □) at an applied voltage of 500 V. ), The volume resistivity of the entire conveying belt was a common logarithm of 9.78 (log Ω · cm) at an applied voltage of 500V. The surface roughness Rz was 3.05 μm. The pure water contact angle was 105 °.
Further, the sheet adsorbing property and the peelability at the time of transport of the obtained transport belt were not preferable in practice, and the partial peeling and transport stability were insufficient. In addition, regarding stain resistance, ink stains were present on the entire surface of the conveying belt.

  As is apparent from Table 1, the conveyance belt of the present invention is excellent in both paper adsorbability and stain resistance. Such a conveying belt can contribute to the formation of a good image because of high paper feeding accuracy, and it does not easily contaminate even when used for a long period of time. . As is apparent from a comparison between Comparative Example 3 and Examples 1 and 2, such an effect can be obtained by setting the surface resistivity of the outer layer to one digit or more than the surface resistivity of the inner layer. Furthermore, the said effect becomes more remarkable by making the volume resistivity of the whole conveyance belt, the surface roughness of an outer layer, and the pure water contact angle of an outer layer into a specific range.

  The conveying belt of the present invention can be widely used for conveying paper in image forming apparatuses such as double electrophotographic apparatuses (for example, copying machines, laser beam printers, facsimiles), ink jet printer apparatuses, and printing machines.

1 Inner layer 2 Outer layer

Claims (9)

  An inner layer containing a polyimide resin containing a conductive substance and an outer layer whose surface resistivity is one digit or more higher than the surface resistivity of the inner layer, and the overall volume resistivity is a common logarithm of 7 to 12 (log Ω · cm) There is a conveyor belt.   The conveying belt according to claim 1, wherein a content ratio of the conductive material in the inner layer is 3 to 40 parts with respect to 100 parts of the polyimide resin.   The conveyance belt according to claim 1 or 2, wherein the surface resistivity of the inner layer is a common logarithmic value of 6 to 13 (log Ω / □).   The conveyance belt according to claim 1, wherein the outer layer includes a fluororesin.   The conveyance belt according to claim 1, wherein the outer layer includes silicone rubber.   The conveyor belt according to claim 4, wherein the outer layer includes a conductive substance, and a content ratio of the conductive substance is 0.5 to 2.0% by weight with respect to a total weight of the outer layer.   The conveyor belt according to claim 5, wherein the outer layer includes a conductive substance, and a content ratio of the conductive substance is 30.0% by weight or less based on a total weight of the outer layer.   The conveyor belt according to claim 1, wherein the outer layer has a surface roughness Rz of 5 μm or less.   The conveyance belt according to any one of claims 1 to 8, wherein a pure water contact angle of the outer layer surface is 90 degrees or more.

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