JP5522774B2 - Conveyor belt - Google Patents

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, and preferably has a volume resistivity. Is 1 × 10 ¹⁵ Ωcm, and a conveying belt is disclosed that stabilizes electric charge by AC charging and electrostatically attracts a recording medium (paper) (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.

  In recent years, downsizing of devices has been progressing. For example, in an inkjet printer, the size of a conveying belt and the diameter of a roll around which the belt is stretched have been reduced following the miniaturization of the apparatus. In such a case, if the conveyor belt is stretched over the roll and left standing for a long time, the shape of the roll remains as a ridge on the belt, and the gap between the inkjet head and the belt fluctuates in this ridge portion. There is a problem in that image defects and runnability defects occur.

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 good cleaning and durability. Is to provide a simple conveying belt.

According to the present invention, a conveyor belt is provided. The conveying belt is seamless, includes a polyimide resin, includes an outer layer having a surface resistivity of 1 × 10 ⁶ to 1 × 10 ¹³ Ω / □, a polyimide resin, and a surface resistivity of 1 ×. The inner layer is 10 ¹³ Ω / □ or more, and the difference between the surface resistivity of the outer layer and the surface resistivity of the inner layer is 2.0 or more in common logarithm.
In a preferred embodiment, the volume resistivity of the entire belt is 1 × 10 ¹² Ω · cm or more.
In preferable embodiment, the thickness of the said outer layer is 25-500 micrometers, and the thickness of the said inner layer is 25-1000 micrometers.
In a preferred embodiment, the inner layer is thicker than the outer layer.
In preferable embodiment, the tensile elasticity modulus of the said belt for conveyance is 2000-6500 Mpa.
In a preferred embodiment, the outer layer has a surface roughness Rz of 5 μm or less.

  According to the present invention, it is possible to obtain a conveyance belt having excellent paper adsorbability and peelability, and excellent cleaning properties and durability. Since the conveyance belt of the present invention exhibits good paper adsorption and peelability, the paper feeding accuracy is high. In addition, the excellent cleaning property makes it difficult for ink stains to adhere and contributes to good image formation.

It is a general | schematic fragmentary enlarged view of the cross section of the belt for conveyance in preferable embodiment of this invention.

A. Overall Configuration of Conveying Belt The conveying belt of the present invention preferably conveys a recording medium in an image forming apparatus that employs a belt conveying method. The recording medium is typically paper. Since the conveyance belt of the present invention has high paper feeding accuracy, it can be suitably used for an inkjet image forming apparatus.

  The conveyor belt of the present invention is a seamless belt that does not have a joint (joint formed when the film is tubular). Therefore, the circumference accuracy is excellent, contributing to good image formation, and excellent durability.

  FIG. 1 is a schematic partial enlarged view of a cross section of a conveying belt according to a preferred embodiment of the present invention. The conveyor belt 10 includes an outer layer 1 and an inner layer 2. Although not shown, the conveyor belt 10 may further include any appropriate intermediate layer between the outer layer and the inner layer as long as the effects of the present invention are obtained. 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 outer layer 1 and the inner layer 2 contain a polyimide resin. Since both the outer layer 1 and the inner layer 2 contain a polyimide resin, the adhesion between the layers is improved, so that both the surface property of the belt and the releasability can be satisfactorily achieved. In addition, a single-layer conveying belt containing a polyimide resin has a problem that the cleaning performance is deteriorated because the belt surface is contaminated by ink mist, ink stains, and the like. In the present invention, these problems can be solved by configuring the conveyor belt from two or more layers having a predetermined surface resistivity.

The outer layer 1 has a surface resistivity of 1 × 10 ⁶ to 1 × 10 ¹³ Ω / □, and the inner layer 2 has a surface resistivity of 1 × 10 ¹³ Ω / □ or more. The difference between the surface resistivity of the inner layer and the surface resistivity of the outer layer is 2.0 or more in common logarithm, preferably 2.5 or more, and more preferably 3.0 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 conveying belt that achieves both sheet adsorbability and releasability and is excellent in cleaning properties. In a conventional conveyor belt, an insulating layer that is easily charged for electrostatically adsorbing paper is usually employed as an outer layer. On the other hand, in the present invention, by adopting a semiconductive outer layer and an insulating inner layer, the surface charge of the belt can be stably maintained, and appropriate neutralization can be imparted to the belt. Can be stabilized. As described above, it is one of the features of the present invention to stabilize the sheet posture by using the semiconductive outer layer and the insulating inner layer.

The volume resistivity of the entire conveying belt of the present invention is preferably 1 × 10 ¹² Ω · cm or more, and more preferably 1 × 10 ¹³ Ω · cm or more. 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 conveying belt can be controlled by adding a conductive material to the outer layer and the inner layer as necessary.

  The tensile elastic modulus of the entire conveying belt of the present invention is preferably 2000 to 6500 MPa, more preferably 2500 to 6000 MPa, and particularly preferably 3000 to 5500 MPa. When the tensile elastic modulus of the conveying belt is in such a range, it is possible to obtain a conveying belt that is compatible with both sheet adsorbability and peelability, suppresses fluctuations in conveying belt speed, and has excellent durability.

B. Outer layer The outer layer contains a polyimide resin and has a surface resistivity of 1 × 10 ⁶ to 1 × 10 ¹³ Ω / □. If the surface resistivity of the outer 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 conveyance belt that is excellent in both sheet adsorbability and releasability, suppression of conveyance belt speed fluctuation, charge uniformity, and separation discharge property. The surface resistivity of the outer layer is preferably 1 × 10 ⁸ to 1 × 10 ¹² Ω / □. Within such a range, the surface charge of the belt can be stably maintained, and appropriate neutralization can be imparted to the belt, so that the sheet posture can be suitably stabilized.

  The outer layer typically includes a polyimide resin and a conductive material. By including a conductive material, it is possible to impart semiconductivity to the transport belt. Moreover, the said surface resistivity can be controlled by adjusting the kind and content of an electroconductive substance.

  Any appropriate polyimide resin can be adopted as the polyimide resin. For example, the copolymer of tetracarboxylic dianhydride or its derivative (s) and a diamine compound is mentioned.

  Specific examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetra. Carboxylic dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic Acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic 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) ether dianhydride, ethylenetetracarboxylic dianhydride

  Specific examples of the diamine compound include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl-4,4′-biphenyldiamine, benzidine, 3,3′-dimethylbenzidine 3,3′-dimethoxybenzidine, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylpropane, 2,4-bis (β-amino-t-butyl) toluene, bis (p-β-amino) -T-butylphenyl) ether, bis (p-β-methyl-δ-aminopheny) ) 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-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2, 11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5 -Methyl nonamechi Range amine, 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. Typically, carbon black can be employed.

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 outer layer and the entire transport belt and that has excellent mechanical strength is provided. Can be obtained.

  The thickness of the outer layer is preferably 25 to 500 μm, more preferably 25 to 200 μm.

  The surface roughness Rz of the outer layer is preferably 5 μm or less, more preferably 3 μm or less, and particularly preferably 2 μm or less. If the surface roughness Rz of the outer layer is in such a range, a conveying belt having excellent cleaning properties can be obtained. Further, since the surface releasability is maintained even after cleaning with a blade or the like, the cleaning property can be maintained over a long period of time, and the gloss of the surface of the conveying belt can be maintained.

C. Inner layer The inner layer contains a polyimide resin and has a surface resistivity of 1 × 10 ¹³ Ω / □ or more. When the surface resistivity of the inner layer is in such a range, the charge can be stably held when the conveying belt is charged. As a result, it is possible to obtain a conveyance belt that is excellent in both sheet adsorbability and releasability, suppression of conveyance belt speed fluctuation, charge uniformity, and separation discharge property.

  As said polyimide resin, the polyimide resin as described in said B term can be used, for example. Preferably, the same type of polyimide resin as the polyimide resin contained in the outer layer can be used. Here, “the same kind of polyimide resin” includes a polyimide resin in which some of the constituent monomers are common, and preferably includes a polyimide resin in which all of the monomers are common. In this case, since the adhesion between the layers is further improved, both the surface properties of the belt and the releasability can be satisfactorily achieved.

  As long as the inner layer exhibits the surface resistivity, the inner layer may contain a conductive substance depending on the use of the conveyor belt. As the conductive substance, for example, the conductive substance described in the above section B can be used. The content ratio of the conductive material is preferably 2.0% by weight or less with respect to the total weight of the inner layer.

  The thickness of the inner layer is preferably 25 to 1000 μm, more preferably 30 to 500 μm, and particularly preferably 40 to 300 μm. The thickness of the inner layer is preferably larger than the thickness of the outer layer. By making the thickness of the inner layer larger than the thickness of the outer layer, the charge during charging can be suitably maintained, and as a result, both stable adsorptivity and peelability can be achieved. Moreover, since the inner layer does not contain a conductive substance or contains a small amount, it has excellent mechanical strength such as tensile elastic modulus. Therefore, the mechanical strength of the conveyor belt can be improved by increasing the thickness of the inner layer. In addition, even when used in a small-sized image forming apparatus, an effect that roll wrinkles hardly remain can be achieved.

D. Method for Forming Conveying Belt Any appropriate method can be adopted as a method for forming the conveying belt of the present invention. For example, a conveyor belt including an outer layer and an inner layer containing a polyimide resin is
(1) Dispersing the conductive substance in an organic polar solvent to prepare a conductive substance dispersion,
(2) After dissolving the tetracarboxylic dianhydride or derivative thereof and the diamine compound in a conductive substance dispersion, a polymerization reaction is performed to prepare a conductive substance-dispersed polyamic acid solution for outer layer formation,
(3) After expanding the conductive material-dispersed polyamic acid solution for forming the outer layer in a cylindrical mold, the organic polar solvent is dried to form a tubular conductive material-dispersed polyimide precursor layer,
(4) After dissolving the tetracarboxylic dianhydride or derivative thereof and the diamine compound in an organic polar solvent, a polyamic acid solution for inner layer formation is prepared by polymerization reaction,
(5) After the polyamic acid solution for forming the inner layer is developed on the inner surface of the tubular conductive material-dispersed polyimide precursor layer, it can be obtained by advancing the ring-closing imidization reaction. In addition, in this formation method, you may perform a process (4) before a process (3).

D-1. Process (1)
In step (1), the conductive material is dispersed in an organic polar solvent to prepare a conductive material dispersion. 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, hexamethyl Examples thereof include phosphortriamide, N-methyl-2-pyrrolidone, pyridine, tetramethylene sulfone, dimethyltetramethylene sulfone and the like. Of these, N-methyl-2-pyrrolidone and N, N-dialkylamides such as N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide and the like are preferable. . This is because the dispersion solvent for the conductive material can be used as a polymerization reaction solvent for the subsequent step. 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. An 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.

  A dispersant may be further added to the conductive substance dispersion. By adding a dispersant, the conductive substance can be suitably dispersed in the organic polar solvent, and the uniformity of the surface resistivity and volume resistivity of the outer layer can be improved. 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.

D-2. Process (2)
In step (2), the tetracarboxylic dianhydride or derivative thereof and a diamine compound are dissolved in the conductive substance dispersion, and then subjected to a polymerization reaction to thereby form a conductive substance-dispersed polyamic acid for forming an outer layer. Obtain a 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 polyamic acid solution may contain one type of polyamic acid or a mixed solution of two or more types of polyamic acid.

  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. Moreover, reaction time becomes like this. Preferably it is 1 to 10 hours, More preferably, it is 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.

D-3. Step (3)
In step (3), the conductive substance-dispersed polyamic acid solution for forming the outer layer is developed in a cylindrical mold, and then the organic polar solvent is dried to form a tubular conductive substance-dispersed polyimide precursor layer. To do. 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. Preferably, the heating method includes a method of heating while rotating the mold, a method using high-precision hot air circulation, a method of charging at a low temperature to reduce the rate of temperature rise, and a combination of these methods. According to such a heating method, the conductive material-dispersed polyamic acid solution can be heated evenly, and the aggregation variation of the conductive material can be suppressed. As a result, the surface resistivity of the outer layer and the volume resistivity of the entire conveying belt can be made uniform. The drying conditions can be appropriately set according to the type and concentration of the solvent. For example, the drying temperature can be 100-150 ° C. Also, the drying time can be 10-60 minutes.

D-4. Step (4)
In the step (4), the tetracarboxylic dianhydride or derivative thereof and the diamine compound are dissolved in an organic polar solvent and then subjected to a polymerization reaction to obtain a polyamic acid solution for forming an inner layer. In addition, the organic polar solvent may contain the electroconductive substance and the dispersing agent as needed. As the constituents of the polyamic acid solution for forming the inner layer (organic polar solvent, tetracarboxylic dianhydride or derivative thereof, diamine compound, conductive substance, dispersant, etc.), the above-mentioned conductive substance-dispersed polyamide for forming the outer layer The thing similar to the component which comprises an acid solution is mentioned. As the polymerization reaction conditions, the conditions described in the above step (2) may be employed.

D-5. Process (5)
In step (5), the polyamic acid solution for forming the inner layer is developed on the inner surface of the tubular conductive material-dispersed polyimide precursor layer, and then the ring-closure imidization reaction proceeds. As a developing method, the method described in the above step (3) can be adopted. The organic polar solvent in the developed polyamic acid solution may be removed by heat drying before the ring-closure imidization reaction, or may be removed during the reaction. The ring-closing imidization reaction can proceed by simultaneously heating both the tubular conductive material-dispersed polyimide precursor layer (outer layer) and the polyamic acid solution developed on the inner surface thereof or the dried product layer (inner layer) thereof. . The heating temperature is preferably 250 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, it is possible to uniformly heat the outer layer and the inner layer containing the conductive substance, and to suppress the aggregation variation of the conductive substance. As a result, the surface resistivity of the outer layer and the inner layer, and the volume resistivity of the entire conveying belt can be made uniform.

  As described above, by forming into a tubular shape, it is possible to obtain a transport belt 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.

  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]
Using UP MCP-HT450 (manufactured by Mitsubishi Chemical Corporation, probe: UR) as a Hiresta, surface resistivity and volume resistivity at 25 ° C. and 60% RH were measured under an applied voltage of 500 V for 10 seconds. In addition, in the common logarithm value of 8.0 or less, since measurement is impossible at 500V, the voltage was lowered and measurement was performed at an applied voltage of 10V.

[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, and the average value was defined as the surface roughness Rz.

[Tensile modulus]
Using a tensile tester (Orientec UTM1000 Tensilon) with a conveyor belt punched in the shape of No. 3 dumbbell (JIS K 6301) in the longitudinal direction as a sample, pulling speed 100mm / The measurement was performed under the conditions of min and the distance between chucks of 30 mm.

[Suction transportability]
The transport belt obtained in the examples and the like is mounted on a roll as a paper transport belt for an inkjet printer, and is printed for 6 hours in an environment of room temperature and humidity 50% Rh using printing paper made of plain paper. Then, according to the following criteria, the paper adsorption transportability was evaluated.
○ ・ ・ ・ Adhesiveness and releasability of paper are good and can be printed without problems △ ・ ・ ・ Adsorption and releasability of paper are generally good, but problems such as partial peeling sometimes occur × ・ ・・ There are problems with the adsorptivity and peelability of the paper, and problems such as partial peeling frequently occur.

[Cleanability]
The transport belt obtained in the examples and the like is mounted on a roll as a paper transport belt for an inkjet printer, and is printed for 6 hours in an environment of room temperature and humidity 50% Rh using printing paper made of plain paper. The appearance of the conveyor belt after the inspection was visually confirmed, and the cleaning property was evaluated according to the following criteria.
○ ・ ・ ・ No toner stains on the conveyor belt surface ×… Toner stains on the entire conveyor belt surface

<Example 1>
By adding 300 g of dried carbon black (Tegusa Japan, Special Black 4) in 1700 g of N-methyl-2-pyrrolidone (NMP) and stirring for 12 hours at room temperature in a ball mill, 15% carbon black A dispersion was obtained.

  1229.2 g of the obtained carbon black dispersion was transferred to a 5000 mL four-necked flask, and 2899.2 g of NMP, 105.1 g of p-phenylenediamine (PDA), and 194.6 g of 4,4′-diaminodiphenyl ether (DDE). Charged and dissolved with stirring at room temperature. Next, 572.0 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) was added, reacted at 25 ° C. for 1 hour, and then heated at 75 ° C. for 20 hours. Carbon black-dispersed polyamic acid solution for forming an outer layer having a solution viscosity of 160 Pa · s measured by a mold viscometer (solid content (part excluding water generated from ring closure imidization reaction from polyamic acid) concentration 20 wt%, amount of carbon black added : 23 parts) with respect to the resin.

  3931.3 g of NMP, PDA 128.8 g, and DDE 238.6 g were charged into a four-necked flask and dissolved at room temperature with stirring. Next, 701.3 g of BPDA was added and dissolved, reacted at 25 ° C. for 1 hour, and then heated at 75 ° C. for 20 hours to obtain a polyamic acid solution for inner layer formation.

  The carbon black-dispersed polyamic acid solution for forming the outer layer was applied to a thickness of 150 μm with a dispenser on the inner surface of a cylindrical mold having an inner diameter of 100 mm and a length of 500 mm, and then rotated at 1500 rpm for 10 minutes to obtain a uniform coated surface. Next, while rotating at 250 rpm, hot air at 130 ° C. was applied for 30 minutes from the outside of the mold, and then cooled to room temperature, to obtain a tubular carbon black-dispersed polyimide precursor layer.

On the inner surface of the obtained tubular carbon black-dispersed polyimide precursor layer, the polyamic acid solution for forming the inner layer was applied to a thickness of 300 μm in the same manner as the carbon black-dispersed polyamic acid solution for forming the outer layer, and dried. . Subsequently, the temperature was raised to 300 ° C. at a rate of temperature rise of 2 ° C./min, and further heated at 300 ° C. for 15 minutes to remove the solvent, remove dehydrated ring-closing water, and imidize (cure). Then, it cooled to room temperature and peeled from the metal mold | die, and the semiconductive conveyance belt which has a semiconductive layer in an outer layer and has an insulating layer in an inner layer was obtained. The total thickness of the obtained conveyance belt was 90 μm, the thickness of the outer layer was 32 μm, and the thickness of the inner layer was 58 μm. When the surface resistivity was measured, the surface resistivity of the outer layer was 1 × 10 ¹⁰ Ω / □, the surface resistivity of the inner layer was 1 × 10 ¹³ Ω / □ or more, and the volume resistivity was 1 × 10 ¹³ Ω · cm. there were. Further, the tensile elastic modulus of the conveyor belt was 4200 MPa, and the surface roughness Rz of the outer layer was 0.6 μm.

  The obtained transport belt was mounted on a roll as a paper transport belt for an ink jet printer, and was printed for 6 hours in an environment of room temperature and humidity 50% Rh using printing paper made of plain paper. A good image was obtained. In addition, the paper adsorption conveyance property and cleaning property at that time were evaluated. The results are shown in Table 1.

<Example 2>
A carbon black-dispersed polyamic acid solution for forming an outer layer in which the addition amount of carbon black is 21.0 parts with respect to the resin (solid content concentration: 20 wt%, addition amount of carbon black: 21.0 parts with respect to the resin) A semiconductive transport belt was obtained in the same manner as in Example 1 except that it was used. The total thickness of the obtained conveyance belt was 90 μm, the thickness of the outer layer was 29 μm, and the thickness of the inner layer was 61 μm. When the surface resistivity was measured, the surface resistivity of the outer layer was 1 × 10 ¹¹ Ω / □, the surface resistivity of the inner layer was 1 × 10 ¹³ Ω / □ or more, and the volume resistivity was 1 × 10 ¹⁴ Ω · cm. there were. Further, the tensile elastic modulus of the conveyor belt was 4150 Mpa, and the surface roughness Rz of the outer layer was 0.7 μm.

  The obtained transport belt was mounted on a roll as a paper transport belt for an ink jet printer, and was printed for 6 hours in an environment of room temperature and humidity 50% Rh using printing paper made of plain paper. A good image was obtained. In addition, the paper adsorption conveyance property and cleaning property at that time were evaluated. The results are shown in Table 1.

<Example 3>
In the same manner as in Example 1, except that the coating thickness of the carbon black-dispersed polyamic acid solution for forming the outer layer was set to 300 μm, and the coating thickness of the polyamic acid solution for forming the inner layer was set to 150 μm. A conveyor belt was obtained. The total thickness of the obtained conveyance belt was 90 μm, the thickness of the outer layer was 61 μm, and the thickness of the inner layer was 29 μm. When the surface resistivity was measured, the surface resistivity of the outer layer was 3 × 10 ⁹ Ω / □, the surface resistivity of the inner layer was 1 × 10 ¹³ Ω / □ or more, and the volume resistivity was 1 × 10 ¹³ Ω · cm. there were. Further, the tensile elastic modulus of the transport belt was 4100 Mpa, and the surface roughness Rz of the outer layer was 0.6 μm.

  The obtained transport belt was mounted on a roll as a paper transport belt for an ink jet printer, and was printed for 6 hours in an environment of room temperature and humidity 50% Rh using printing paper made of plain paper. A good image was obtained. In addition, the paper adsorption conveyance property and cleaning property at that time were evaluated. The results are shown in Table 1.

<Comparative Example 1>
Except that the coating thickness of the carbon black-dispersed polyamic acid solution for forming the outer layer on the inner surface of the mold was 450 μm, and the polyamic acid solution for forming the inner layer was not applied, the same as in Example 1, A semiconductive conveyor belt was obtained. The total thickness of the obtained conveyance belt was 90 μm. The surface resistivity of the conveyance belt was 1 × 10 ¹¹ Ω / □, and the volume resistivity was 1 × 10 ⁹ Ω · cm. The conveyance belt had a tensile modulus of 4100 MPa and a surface roughness Rz of 0.6 μm.

  The obtained transport belt is mounted on a roll as a paper transport belt for an ink jet printer, and is printed for 6 hours in a room temperature and humidity of 50% Rh using printing paper made of plain paper. Adsorption transportability and cleaning performance were evaluated. The results are shown in Table 1.

<Comparative example 2>
Carbon black-dispersed polyamic acid solution obtained by adding 30.0 parts of special black 4 to the polyamic acid solution for forming the inner layer (solid content concentration: 20 wt%, added amount of carbon black: 30.0 parts to the resin) The semiconductive transport belt was obtained in the same manner as in Example 1 except that the inner layer was formed using The total thickness of the obtained conveying belt was 90 μm, the thickness of the outer layer was 31 μm, and the thickness of the inner layer was 59 μm. When the surface resistivity was measured, the surface resistivity of the outer layer was 1 × 10 ⁷ Ω / □, the surface resistivity of the inner layer was 1 × 10 ⁵ Ω / □, and the volume resistivity was 1 × 10 ⁵ Ω · cm. It was. Further, the tensile elastic modulus of the conveyor belt was 3550 Mpa, and the surface roughness Rz of the outer layer was 1.1 μm.

  The obtained transport belt is mounted on a roll as a paper transport belt for an ink jet printer, and is printed for 6 hours in a room temperature and humidity of 50% Rh using printing paper made of plain paper. Adsorption transportability and cleaning performance were evaluated. The results are shown in Table 1.

<Comparative Example 3>
Carbon black-dispersed polyamic acid solution obtained by adding 18.0 parts of carbon black (Tegusa Japan, Special Black 4) to the polyamic acid solution for forming the inner layer with respect to the resin (solid content concentration: 20 wt%, carbon black addition amount: resin A semiconductive transport belt was obtained in the same manner as in Example 1 except that the inner layer was formed using 18.0 parts). The total thickness of the obtained conveying belt was 90 μm, the thickness of the outer layer was 27 μm, and the thickness of the inner layer was 63 μm. When the surface resistivity was measured, the surface resistivity of the outer layer was 1 × 10 ¹⁰ Ω / □, the surface resistivity of the inner layer was 3 × 10 ¹¹ Ω / □, and the volume resistivity was 1 × 10 ¹² Ω · cm. It was. Further, the tensile elastic modulus of the transport belt was 3950 Mpa, and the surface roughness Rz of the outer layer was 0.9 μm.

  The obtained transport belt is mounted on a roll as a paper transport belt for an ink jet printer, and is printed for 6 hours in a room temperature and humidity of 50% Rh using printing paper made of plain paper. Adsorption transportability and cleaning performance were evaluated. The results are shown in Table 1.

<Comparative Example 4>
In the same manner as in Example 1, except that the outer layer was formed using the polyamic acid solution for forming the inner layer, and the inner layer was formed using the carbon black-dispersed polyamic acid solution for forming the outer layer, A conveyor belt was obtained. The total thickness of the obtained conveyance belt was 90 μm, the thickness of the outer layer was 30 μm, and the thickness of the inner layer was 60 μm. When the surface resistivity was measured, the surface resistivity of the outer layer was 1 × 10 ¹³ Ω / □ or more, the surface resistivity of the inner layer was 1 × 10 ¹⁰ Ω / □, and the volume resistivity was 1 × 10 ¹³ Ω · cm. there were. Further, the tensile elastic modulus of the conveyor belt was 4180 Mpa, and the surface roughness Rz of the outer layer was 0.7 μm.

  The obtained transport belt is mounted on a roll as a paper transport belt for an ink jet printer, and is printed for 6 hours in a room temperature and humidity of 50% Rh using printing paper made of plain paper. Adsorption transportability and cleaning performance were evaluated. The results are shown in Table 1.

  As is apparent from Table 1, the conveyance belt of the present invention is excellent in both the paper adsorption conveyance property and the cleaning property. Such a conveyor belt can contribute to the formation of a good image because of high paper feeding accuracy. In addition, the paper to be conveyed is not soiled because it is difficult for the soil to adhere even after long-term use.

  The transport belt of the present invention can be widely used as a transport belt for electrophotographic apparatuses such as copying machines, laser beam printers, facsimiles, and the like, and a transport belt for transporting paper in an ink jet printer apparatus, drying paper, and the like. Preferably, it can be used as a conveyor belt for an inkjet printer apparatus.

1 outer layer 2 inner layer 10 conveyor belt

Claims (5)

Comprising a polyimide resin, and the outer layer surface resistivity of ^{10 13 Ω / □ 1 × 10} 6 ~1 ×, includes a polyimide resin, an inner layer is the surface resistivity of 1 × 10 ¹³ Ω / □ or more includes, Ri difference der 2.0 or more in common logarithm of the surface resistivity and the inner layer of the surface resistivity of the outer layer, the thickness of the inner layer is thicker than the thickness of the outer layer, seamless shaped conveyor belt. The conveyance belt according to claim 1, wherein the volume resistivity of the entire belt is 1 × 10 ¹² Ω · cm or more. The conveying belt according to claim 1 or 2, wherein the outer layer has a thickness of 25 to 500 µm, and the inner layer has a thickness of 30 to 1000 µm. The conveyance belt according to any one of claims 1 to 3 , wherein the tensile elastic modulus is 2000 to 6500 MPa. Surface roughness Rz of said outer layer is 5μm or less, conveyor belt according to any one of claims 1 to 4.

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