JP5765880B2 - Inkjet conveyor belt - Google Patents

Description

  The present invention relates to an inkjet transport belt, a method for manufacturing the same, and an inkjet recording apparatus.

  In the ink jet recording apparatus, ink liquid is discharged while scanning the ink jet head in the main scanning direction, and when the scanning of the ink jet head for one line is completed, the recording medium is transported by a predetermined amount in the sub scanning direction, and the ink jet head is moved again. Scanning in the main scanning direction forms an image on the recording medium. Since the recording medium needs to be accurately conveyed by a predetermined amount, the conveying belt is charged and the recording medium is attracted to the surface of the conveying belt by static electricity and conveyed. Various types of conveyor belts as described below are known.

The conveyance belt of Patent Document 1 has a structure having two layers made of ETFE or the like, and the volume resistivity is preferably set to 10 ¹⁵ (Ω · cm), and the charge due to AC charging is stabilized and recorded. The medium can be electrostatically adsorbed. In addition, the effects of molding unevenness and undulations during heat molding, surface roughness due to uneven distribution of conductive fillers such as carbon black, cleaning properties due to deterioration in surface properties, image degradation (color registration degradation), surface dents due to thermoplastic polymer, pressure welding There were problems such as traces, deformation, and fluctuations in belt speed.

  Further, due to the recent increase in environmental awareness, water-based pigment ink or water-based dye ink is mainly used as the ink. Since these are water-based, a drying process is required to improve the printing speed, and the belt needs heat resistance. However, an ETFE two-layer belt such as that disclosed in Patent Document 1 is not heat resistant, and thus is thermally deformed, resulting in poor conveyance of the paper due to poor adsorbability of the paper to the belt, leading to image defects.

Further, in Patent Document 2, it is a seamless belt-shaped, inkjet transport belt comprising at least one layer, and the innermost layer contains at least one of a polyamide resin, a polyester resin, and a polyimide resin as a resin component, An inkjet transport belt that contains a conductive filler and has a volume resistivity of 10 ¹⁰ to 10 ¹⁴ (Ω · cm) has been proposed. Furthermore, an inkjet seamless belt is proposed in which a release coating treatment or a release film treatment having a thickness of 1 to 100 μm is applied to the belt. However, an inkjet transport belt having a volume resistivity of 10 ¹⁰ to 10 ¹⁴ (Ω · cm) has insufficient sheet adsorbing power when using thick paper, and therefore has poor sheet transport performance.

Patent Document 3 is a single-layer seamless belt, includes at least one of a polyimide resin and a polyamideimide resin as a resin component, further contains a conductive filler, and has a volume resistivity of 10 ¹⁰ to 10 ¹⁴ (Ω Ink transport belts that are cm) have been proposed. However, since the belt is manufactured by any one of the flow coating method, the ring flow coating method, and the centrifugal molding method, film thickness control at the time of resin melting in the conveyance belt of Patent Document 1 and maintenance of smoothness due to the effect of residual strain However, there is a concern that polyimide resin and polyamideimide resin have high affinity with ink and cause poor cleaning.

Patent Document 4 is a seamless belt shape of two or more layers, and the resin component contained in each layer is the same type of polyimide resin, and the volume resistivity of the outermost layer is 10 ¹⁴ to 10 ¹⁶ (Ω Ink jet transport belts have been proposed in which the innermost layer has a volume resistivity of 10 ¹⁸ to 10 ¹⁴ (Ω · cm). However, also in this case, the polyimide resin and the polyamide-imide resin have a problem of high affinity with ink and poor cleaning.

Japanese Patent Laid-Open No. 2003-103857 JP 2007-308241 A JP 2007-307755 A JP 2008-94605 Gazette

  The present invention aims to solve the above problems. That is, the present invention relates to an inkjet transport belt excellent in durability, paper transportability, paper suction performance, abrasion resistance, and ink cleaning properties and excellent in suction performance regardless of the type of paper, and an ink jet recording apparatus. The purpose is to provide.

  As a result of intensive studies to achieve the above object, the present inventor has obtained a multilayer seamless belt comprising at least two layers having an ethylene / tetrafluoroethylene copolymer as an outer layer and a conductive polyimide resin as an inner layer. I found that the problem could be solved. As a result of further research based on this knowledge, the present invention has been completed.

  That is, this invention provides the following multilayer endless tubular belt and its manufacturing method.

Item 1. A multilayer seamless belt comprising at least two layers having an outer layer containing an ethylene / tetrafluoroethylene copolymer and an inner layer containing a conductive polyimide-based resin, the outer layer having a thickness of 10 to 150 μm, and the surface of the inner layer A multilayer seamless belt having a resistivity of 1 × 10 ⁴ to 1 × 10 ⁹ (Ω / □).

  Item 2. Item 2. The multilayer seamless belt according to Item 1, wherein the conductive polyimide resin contains a resin selected from the group consisting of thermoplastic polyimide, thermosetting polyimide, polyetherimide, and polyamideimide, and conductive carbon black.

  Item 3. Item 3. The multilayer seamless belt according to Item 1 or 2, wherein the inner peripheral surface of the outer layer is chemically treated.

Item 4. Item 4. The multilayer seamless belt according to any one of Items 1 to 3, wherein the ethylene / tetrafluoroethylene copolymer contained in the outer layer absorbs at 1720 to 1800 cm ⁻¹ by infrared spectroscopy.

  Item 5. Item 5. An inkjet transport belt comprising the multilayer seamless belt according to any one of Items 1 to 4.

  Item 6. Item 6. An ink jet recording apparatus comprising the ink jet conveyance belt according to Item 5.

  Item 7. Item 7. The inkjet recording apparatus according to Item 6, including a mechanism for electrostatically attracting and transporting the recording medium to the inkjet transport belt according to Item 5.

Item 8. A method of manufacturing a multilayer seamless belt,
(1) A step of producing a cylindrical belt (inner layer) made of a conductive polyimide resin by centrifugally molding a conductive polyamic acid solution;
(2) A step of producing a cylindrical belt (outer layer) by molding an ethylene / tetrafluoroethylene copolymer into a cylindrical shape by a molding method using melt extrusion, and (3) produced in (1) above. A process of fusing together the inner peripheral surface of the belt (outer layer) manufactured in (2) above to the outer peripheral surface of the belt (inner layer),
Manufacturing method.

  The inkjet transport belt of the present invention is a multilayer seamless belt having at least two layers including an inner layer (base material layer) made of a conductive polyimide resin and an outer layer (outer surface layer) made of an ethylene / tetrafluoroethylene copolymer. Therefore, it is excellent in durability, paper transportability, paper adsorbability, abrasion resistance and ink cleaning properties. In particular, the adsorptivity to paper is good regardless of the type of paper.

It is a schematic diagram which shows the state of the belt biaxial stretching employ | adopted when evaluating the conveyance property (flatness) of a belt.

1: Belt 2: Metal shaft 3: Weight

Hereinafter, the present invention will be described in detail.
1. Inkjet transport belt The inkjet transport belt of the present invention is a seamless belt (or endless tubular belt), and includes an outer layer (outer surface layer) containing an ethylene / tetrafluoroethylene copolymer (hereinafter also referred to as “ETFE”), And a multilayer seamless belt comprising at least two layers having an inner layer (base material layer) containing conductive polyimide resin (hereinafter also referred to as “PI resin”). By including the polyimide resin component, the conveyor belt removes residual strain during molding by removing the solvent during film formation and crosslinking during imidization, and can reduce dimensional fluctuations and waviness when the environment changes. Long changes can also be reduced. In addition, by using the above-mentioned ethylene / tetrafluoroethylene copolymer as an outer layer, it retains excellent electrostatic attraction to the recording medium (paper), and has excellent releasability from the recording medium (paper) after static elimination. Can be granted. Further, the ink cleaning property is excellent.

  The thickness of the outer layer is usually 10 to 150 μm, preferably 30 to 100 μm, more preferably 40 to 70 μm. Moreover, the thickness of an inner layer is 50-200 micrometers normally, Preferably it is 60-100 micrometers, More preferably, it is 50-80 micrometers.

  The ratio of the thickness of the outer layer to the inner layer is usually 1/5 to 3/4, preferably 1/2 to 1/1.

The ethylene / tetrafluoroethylene copolymer contained in the outer layer is a copolymer of ethylene and tetrafluoroethylene, and the molar ratio of monomers of ethylene and tetrafluoroethylene is 60/40 to 40/60, preferably 45. / 55 to 55/45. Further, MFR (5.0 kg, 297 ° C.) is not particularly limited as long as it can be formed into a tube shape, but is usually 4 to 9, preferably 4 to 7.2, more preferably 5 to 5. 7.2. In order to improve crystallinity, a small amount of a third component may be contained in the composition of the copolymer. Specific examples of the copolymer include Tefzel 290 manufactured by Mitsui DuPont Fluorochemical, Fullon ETFE C-55AXB manufactured by Asahi Glass, and the like. Further, the ethylene / tetrafluoroethylene copolymer includes those that are imparted with adhesiveness and capable of being melt-bonded to other materials. The copolymer exhibits a characteristic infrared absorption spectrum at 1720 to 1800 cm ⁻¹ in infrared spectroscopy. As such an ethylene / tetrafluoroethylene copolymer, an ethylene / tetrafluoroethylene copolymer described in JP-A-11-320770 can be mentioned. Specific examples that are generally commercially available include Fullon LM-ETF AH2000 manufactured by Asahi Glass.

  By performing chemical treatment such as chemical etching on the inner peripheral surface of the outer layer containing the ethylene / tetrafluoroethylene copolymer, the adhesiveness with the inner layer containing the conductive polyimide resin can be improved. Accordingly, it is possible to extend the life of the belt by preventing peeling of the inner layer and the outer layer due to use over time.

The surface resistivity of the inner layer (base material layer) is usually 10 ⁴ to 10 ⁹ (Ω / □), preferably 10 ⁴ to 10 ⁸ (Ω / □), more preferably 10 ⁵ to 10 ⁷ (Ω / □). □). By setting it within this range, it is possible to exhibit excellent electrostatic attraction and transportability of the paper at the time of belt charging, and to exhibit good paper releasability at the time of static elimination.

Surface resistivity of the outer layer (outer surface layer) is usually ^{10 14 ~10 17 (Ω / □} ), preferably ^{10 15 ~10 17 (Ω / □} ), and more preferably 10 ¹⁶ ~10 ¹⁷ (Ω / □).

  The conductive polyimide resin includes a polyimide resin and a conductive material. As the polyimide resin, for example, thermoplastic polyimide, thermosetting polyimide, polyetherimide, polyamideimide and the like can be used. Thereby, deformation of the belt due to the drive roll stretch can be prevented, and stable sheet adsorbability can be imparted. Preferably, it is a thermosetting polyimide.

  As the thermosetting polyimide, those obtained by reacting an aromatic tetracarboxylic acid component and an aromatic diamine component in an organic solvent are preferably used.

  Examples of the aromatic tetracarboxylic acid component include pyromellitic acid, naphthalene-1,4,5,8 tetracarboxylic acid, 2,2 ′, 3,3′biphenyltetracarboxylic acid, naphthalene-2,3,6, 7-tetracarboxylic acid, 2,3,5,6-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-diphenyl ether tetracarboxylic acid, 3,3 ′, 4,4′-benzophenonenontetracarboxylic acid, 3,3 ′, 4,4′-diphenyltetracarboxylic acid, 3,3 ′, 4,4′-diphenylsulfonetetracarboxylic acid, 3,3 ′, 4,4′-azobenzenetetracarboxylic acid, bis (2, 3-dicarboxyphenyl) methane, bis (3,4-dicarboxyphenylmethane), bis (3,4-dicarboxyphenylpropane), bis (3,4-dicarboxyphene) Le) hexafluoropropane and the like, or an acid dianhydride can be mentioned, be a mixture of singly or two of them. Preferred are 3,3 ', 4,4'-diphenyltetracarboxylic acid or its acid dianhydride, and pyromellitic acid.

  Examples of the aromatic diamine component include m-phenyldiamine, p-phenyldiamine, 2,4-aminotoluene, 2,6-aminotoluene, 2,4-diaminochlorobenzene, m-xylylenediamine, 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. P-phenyldiamine or 4,4'-diaminodiphenyl ether (ODA) is preferable.

  Examples of the organic solvent include N-methyl-2-pyrrolidone, N, N-dimethylacetamide, dimethyl sulfoxide, hexamethylphosphonyltriamide and the like. 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.

  In the case of a thermoplastic polyimide, examples of the aromatic tetracarboxylic acid component include the same ones as exemplified for the thermosetting polyimide, but examples of the aromatic diamine component include bis [4- {3- (4 -Aminophenoxy) benzoyl} phenyl] ether, 4,4'-bis (3-aminophenoxy) biphenyl, bis [4- (3-aminophenoxy) phenyl] sulfide, 2,2'-bis [4- (3- Aminophenoxy) phenyl] propane and the like, among which can be used in appropriate combination.

  In the case of polyetherimide, the aromatic diamine component may be the same as that exemplified for the thermosetting polyimide, but the aromatic tetracarboxylic acid component may be, for example, bisphenol-A type tetracarboxylic dianhydride. Can be used, and among these, they can be used in appropriate combinations.

  In the case of polyamideimide, it is prepared from trimellitic anhydride and an aromatic diamine component, and examples of the aromatic diamine component are the same as those exemplified for the thermosetting polyimide.

  Examples of the conductive material include an electron conductive material and an ion conductive material. Examples of the electron conductive conductive material include fillers such as carbon black, graphite, Al, Ni, and copper, and composite oxides such as tin oxide, zinc oxide, K titanate, oxide In, tin oxide-in oxide, and oxide Sb. Things. Examples of the ion conductive material include ammonium salts, sulfonates, cations, nonions, and anionic surfactants.

  Of the conductive materials, carbon black is preferred. Examples thereof include gas black, acetylene black, oil furnace black, thermal black, channel black, and ketjen black. Effective for obtaining the desired conductivity with a smaller amount of mixing are ketjen black, acetylene black and oil furnace black. Ketjen black is a contact furnace carbon black.

The surface resistivity of the inner layer (base material layer) is controlled to 10 ⁴ to 10 ⁹ (Ω / □), preferably 10 ⁴ to 10 ⁸ (Ω / □), using the above conductive material as appropriate. The content of the conductive material varies depending on the desired surface resistivity of the inner layer, but is usually 1 to 50% by weight, preferably 5 to 30% by weight in the inner layer (base material layer).

The surface resistivity is a circular electrode (for example, “URS probe” of Hiresta UP manufactured by Mitsubishi Chemical Corporation) or a four-probe electrode (for example, Mitsubishi Chemical Corporation) in an environment of 23 ° C. and 55% RH. (Loresta made) can be measured. The measurement conditions are, for example, a load of 2.0 kg, a voltage of 10 V, and a charge time of 10 seconds.
2. Production of Inkjet Conveyor Belt The inkjet conveyer belt of the present invention has an outer layer (outer surface layer) containing an ethylene / tetrafluoroethylene copolymer on the outer peripheral surface of an inner layer (base material layer) containing a conductive polyimide resin. It can be manufactured by coating.

  The method for producing the transport belt of the present invention will be described by dividing into cases where the polyimide resin constituting the inner layer is thermosetting or thermoplastic.

  When a thermosetting polyimide is used to form the inner layer, the thermosetting polyimide does not plasticize even when heated later when it becomes a polyimide, so it is molded into a seamless belt using its precursor, that is, polyamic acid. .

As a typical manufacturing method in this case,
(1) A step of producing a cylindrical belt (inner layer) made of a conductive polyimide resin by centrifugally molding a conductive polyamic acid solution;
(2) A step of producing a cylindrical belt (outer layer) by molding an ethylene / tetrafluoroethylene copolymer into a cylindrical shape by a molding method using melt extrusion, and (3) produced in (1) above. The step of fusing together the inner peripheral surface of the belt (outer layer) manufactured in (2) above to the outer peripheral surface of the belt (inner layer) formed is included.

  The inner layer is formed by rotationally molding a conductive material-containing polyamic acid solution. As described above, a polyamic acid solution obtained by polycondensation of an aromatic tetracarboxylic acid component and an aromatic diamine component in a solvent is prepared, and the conductive material is mixed with the solution. Specifically, a conductive material (carbon black or the like) is added to the polyamic acid solution, and sufficiently mixed and dispersed using a ball mill, a high mixer or the like. The solid content concentration of the polyamic acid solution containing the conductive material is usually 10 to 30% by weight, preferably 15 to 25% by weight. The density | concentration of the electrically conductive material in the solid content is 2-20 weight% normally, Preferably it is 5-15 weight%. A polyamic acid solution containing a conductive material is cast into a cylindrical mold (drum), and heat-molded while rotating the drum. Thereby, a cylindrical belt (inner layer) made of conductive polyimide resin is obtained.

  An auxiliary agent can be added to the polyamic acid solution to help compatibility with the conductive material (particularly, carbon black), increase the moldability as the inner layer, and further improve the adhesion to the outer layer. . Examples of the auxiliary agent include a fluorine-based surfactant. The fluorosurfactant includes an anionic type, a cationic type, and a nonionic type, and either an anionic type or a nonionic type is preferably used. The amount of addition is very small, and may be about 0.01 to 1.0% by weight based on the total amount of active ingredients of the belt to be formed.

  The rotational molding of the conductive material-containing polyamic acid solution can be performed by injecting the solution onto the inner peripheral surface while rotating a cylindrical mold (drum). The viscosity of the solution can be appropriately set in consideration of moldability and the thickness of the inner layer to be formed. For example, the viscosity measured with a B-type rotational viscometer (25 ° C.) is usually 500 to 2500 cps. Further, the rotation speed and rotation time (casting time) of the drum may be appropriately determined from the relationship with the viscosity and preheating (meaning heat treatment for evaporating the organic polar solvent). At first, inject while slowly rotating. When the injection of the entire amount is completed, for example, the rotational speed is kept at 2 to 200 rad / s, preferably 10 to 100 rad / s, and the mold is gradually heated to heat the mold. Heating is performed at about 180 ° C. or less to evaporate and remove the organic solvent to obtain a tubular (cylindrical) polyamic acid belt. The drum inner peripheral surface is preferably mirror-finished. Thereby, an inner layer having a diameter of various sizes can be easily formed with high thickness accuracy.

The polyamic acid belt is released from the drum metal mold and heated for imidization. The heating temperature is about 250 to 450 ° C., but it is preferable that the temperature is gradually raised at a low temperature and then heated at a high temperature. This heating may be hot air or under reduced pressure. Thereby, a cylindrical belt (inner layer) made of a polyimide resin having a surface resistivity of 10 ³ to 10 ¹⁰ (Ω / □) is obtained. The inner diameter of the obtained belt is usually about 5 to 60 cm, and the thickness is 60 to 100 μm, more preferably 50 to 80 μm.

  There is no particular limitation on the method for forming the outer layer containing the ethylene / tetrafluoroethylene copolymer, and the outer layer can be formed into a cylindrical shape by a normal melt extrusion method or the like. For example, an ethylene / tetrafluoroethylene copolymer can be formed into a cylindrical belt (outer layer) with a circular die using a single screw extruder (cylinder temperature: 280 to 320 ° C.). The inner diameter of the formed belt is usually about 5 to 60 cm, and the thickness is 10 to 150 μm, more preferably 40 to 70 μm.

Next, the inner peripheral surface of the belt (outer layer) is aligned and fused to the outer peripheral surface of the belt (inner layer). Specifically, a release material (for example, a silicone-based release material) is applied to the outer peripheral surface of a metal (aluminum, etc.) cylindrical core as necessary, and then fired, and then the belt (inner layer) is coated. Cover the belt (outer layer) and heat. Usually, two belts are fused by firing at 180 ° C. to 350 ° C. for about 1 to 3 hours using a heating furnace or the like. Thereafter, the multi-layer belt fused from the core is removed, and cut into a predetermined width as necessary to produce an inkjet transport belt. The surface resistivity of the inner layer (conductive layer) of the multilayer belt is usually 10 ⁴ to 10 ⁹ (Ω / □), preferably 10 ⁴ to 10 ⁸ (Ω / □), more preferably 10 ⁵ to 10 ^7. (Ω / □).

  When the inner layer is formed using thermoplastic polyimide, polyether imide or polyamide imide, these resins are plasticized by heating, so there is no need for two-step molding as in the case of thermosetting polyimide. A seamless belt can be obtained at once by discharging from an annular die with an ordinary extruder. Although it is a polyimide, it has a difference in both thermal characteristics due to the difference in organic group. For example, in the case where two or more oxygen atoms are involved in the main chain bond in the bonding part of the organic group, it has thermoplasticity. The plasticizing temperature of this polyimide is generally 350 to 450 ° C., and extrusion molding can be performed at this temperature.

  As a typical production method in this case, (4) a method of coextrusion molding so that a thermoplastic polyimide resin containing a conductive material is an inner layer and an ethylene / tetrafluoroethylene copolymer is an outer layer can be mentioned. . Or (5) a step of producing a cylindrical belt (inner layer) by molding a thermoplastic polyimide resin containing a conductive material into a cylindrical shape by a molding method using extrusion; (6) ethylene / tetrafluoroethylene A step of producing a cylindrical belt (outer layer) by molding the copolymer into a cylindrical shape by a molding method using melt extrusion; and (7) outer periphery of the belt (inner layer) produced in (5) above. There is a method including a step of fusing the inner peripheral surface of the belt (outer layer) produced in the above (6) together with the surface.

A cylindrical belt (inner layer) made of thermoplastic polyimide can be produced as follows. The aromatic diamine component and aromatic tetracarboxylic acid component used for forming the thermoplastic polyimide described above are converted to polyamic acid, and further dehydrated and imidized with acetic anhydride or the like. The thermoplastic polyimide resin may be taken out as a powder by precipitation formation and pelletized. Mixing of thermoplastic polyimide and conductive material (particularly carbon black, etc.) is preferably carried out by kneading with a twin screw extruder (barrel temperature of about 350 to 450 ° C.), sufficiently dispersed and mixed, and granulated into pellets. . The surface resistivity of the thermoplastic polyimide after uniform mixing is about 10 ³ to 10 ¹⁰ (Ω / □). The density | concentration of the electrically conductive material in the thermoplastic polyimide containing an electrically conductive material is 2 to 20 weight% normally, Preferably it is 5 to 10 weight%. In addition, also when using a thermoplastic polyetherimide or polyamideimide, it can be similarly prepared in place of the thermoplastic polyimide.

  The thermoplastic polyimide, polyetherimide or polyamideimide containing the conductive material thus obtained is used as the inner layer of the multilayer belt of the present invention. As a method of laminating the outer layer on the inner layer, for example, a method of laminating the belt (inner layer) and the outer layer at the same time (method (4) above), or separately forming the outer layer and then fusing the inner layer and the outer layer together. The method (the method of said (5)-(7)) is mentioned.

  First, as a method of laminating the inner layer and the outer layer at the same time, for example, the following method can be cited. A circular mandrel die for two-layer extrusion is set at the tip of the discharge port where two extruders join. The nozzle width of the die is adjusted for each of the outer layer and the inner layer, and the inner layer extruder (barrel temperature of about 350 to 450 ° C.) is fed with the kneaded pellets from the outer layer extruder (barrel temperature of about 280 to 320 ° C.). Supplies an ethylene / tetrafluoroethylene copolymer for coextrusion. The thicknesses of the inner layer and the outer layer can be adjusted by appropriately setting the nozzle width and extrusion molding conditions. A mandrel such as an air ring may be used at the die outlet in order to accurately maintain the shape of the tube after discharge. Since it is a continuous tube, when it is used as an inkjet transport belt, it is crossed with a necessary width so that it can be used as a belt.

On the other hand, as a method of forming the inner layer and the outer layer separately and fusing them together, first, a conductive polyimide resin is extruded through a single tubular forming circular die to form a cylindrical polyimide belt. Next, the ethylene / tetrafluoroethylene copolymer is molded into a cylindrical shape by a molding method using melt extrusion to produce a cylindrical belt (outer layer) (see step (2) above). Finally, the cylindrical belt of ethylene / tetrafluoroethylene copolymer is heated on the outer peripheral surface of the cylindrical polyimide belt to fuse the belt in layers. Alternatively, an ethylene / tetrafluoroethylene copolymer previously formed on a cylindrical belt is fitted on the outer peripheral surface of the cylindrical polyimide belt, and then heated and fused. Usually, two belts are fused by firing at 180 ° C. to 350 ° C. for about 1 to 3 hours using a heating furnace or the like. Thereafter, the multi-layer belt fused from the core is removed, and cut into a predetermined width as necessary to produce an inkjet transport belt. The surface resistivity of the inner layer (conductive layer) of the multilayer belt is usually 10 ⁴ to 10 ⁹ (Ω / □), preferably 10 ⁴ to 10 ⁸ (Ω / □), more preferably 10 ⁵ to 10 ^7. (Ω / □).

  The film thickness of the inkjet transport belt obtained as described above is usually 60 to 350 μm, preferably 90 to 200 μm. The inner layer is usually 50 to 200 μm, preferably 60 to 100 μm, and the outer layer is usually 10 to 150 μm, preferably 30 to 100 μm.

  The inkjet transport belt of the present invention is excellent in durability, transportability, adsorbability, abrasion resistance, and ink cleaning properties, and has excellent adsorbability regardless of the recording medium (paper). Therefore, it is used as a conveyor belt in an inkjet recording apparatus. The ink jet recording apparatus has a mechanism for electrostatically attracting and transporting a recording medium (paper) to the transport belt.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The surface resistivity and the solid content concentration of the polyamic acid described in Examples and Comparative Examples were measured as follows.
[Surface resistivity]
The surface resistivity is a circular electrode (for example, “URS probe” of Hiresta UP manufactured by Mitsubishi Chemical Corporation) or a four-probe electrode (for example, Loresta manufactured by Mitsubishi Chemical Corporation) in an environment of 23 ° C. and 55% RH. ) And a load of 2.0 kg, a voltage of 10 V, and a charge time of 10 seconds. A total of 16 points were measured, 4 points at regular intervals in the belt circumferential direction and 4 points at regular intervals in the axial direction, and expressed as an average value.
[Solid content concentration of polyamic acid solution]
The solid content concentration of the carbon black-dispersed polyamic acid solution is a value calculated as follows. The sample is precisely weighed in a heat-resistant container such as a metal cup, and the weight of the sample at this time is defined as A (g). Put the heat-resistant container with the sample in the electric oven, heat and dry while heating up in order of 120 ℃ × 15min, 180 ℃ × 15min, 260 ℃ × 30min, and 280 ℃ × 30min. The weight of the solid content (solid content weight) is defined as B (g). The values of A and B of five samples for the same sample were measured (n = 5) and applied to the following equation to determine the solid content concentration. The average value of the five samples was adopted as the solid content concentration.

Solid content concentration = B / A x 100 (%)
Example 1
A polyamic acid solution obtained by polymerizing an equivalent of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine in N-methylpyrrolidone solvent at room temperature is further added to a solvent. N, N-dimethylacetamide was mixed and diluted. Next, carbon black (Mitsubishi Carbon MA-100, manufactured by Mitsubishi Chemical Corporation) having a DBP (dibutyl phthalate) oil absorption of 100 ml / 100 g dried at 100 ° C. for 2 hours is added to the mixture, and the ball mill is used for 1 hour ( 25 ° C.) well mixed. The composition of the resulting slurry liquid was 15% polyamic acid solid content, 18.0% carbon black (based on polyamic acid solid content), the other was the amount of solvent, and the solution viscosity was 800 cps (25 ° C.). It was.

  This was injected into the inner surface of a metal rotating drum (with a width of 400 mm and an inner diameter of 82 mm; a frame with a width of 20 mm on both sides) with a mirror finish on the inner surface, and the entire amount was injected. The rotation speed was gradually increased, and the rotation was continued at 340 times / minute for 30 minutes. While maintaining this state, the drum was heated to reach 150 ° C., and further rotated at that temperature for 80 minutes to evaporate the solvent and dry. As a result, a polyamic acid tubular seamless belt having a thickness of 50 ± 4 μm and a width of 380 mm was obtained in a semi-dry state. This was removed from the drum.

And the said polyamic-acid belt was covered with metal mandrels, all were put in a hot-air dryer, and it heated up gradually. First, when it reached 300 ° C., it was heated at that temperature for 20 minutes, and when it was further heated to reach 400 ° C., it was heated at that temperature for 20 minutes. By this heating, a polyimide belt having a thickness of 65 ± 5 μm, an inner diameter of 60 mm, and a width of 320 mm was obtained. The surface resistivity of the inner layer belt was 1 × 10 ⁷ (Ω / □).

  An ethylene / tetrafluoroethylene copolymer (Tefzel 290, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was used in a circular die using a φ40 mm single screw extruder (cylinder temperature: 280 to 320 ° C.), and a thickness of 55 mm. A ± 5 μm cylindrical tube was formed.

Separately, a silicone release agent was applied as a release material to the outer peripheral surface of an aluminum cylindrical core having an outer diameter of 60 mm and a length of 400 mm, and baked at 380 ° C. for 1 hour. The cylindrical core was covered with the produced conductive polyimide belt and further covered with an ethylene / tetrafluoroethylene copolymer tube. This was baked in a heating furnace at 200 ° C. for 1 hour and then at 300 ° C. for 1 hour, whereby the tube was fusion-coated on the belt. Thereafter, the resin belt was removed from the core and cut to a width of 300 mm to produce an inkjet transport belt having a total film thickness of 120 μm (outer layer 55 μm, inner layer 65 μm) and inner layer surface resistivity 1 × 10 ⁷ (Ω / □).

Example 2
Polyamide obtained by polymerizing an equivalent of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether (ODA) in N-methylpyrrolidone solvent at room temperature The acid solution was further mixed with a solvent N, N-dimethylacetamide and diluted. Next, carbon black (Mitsubishi Carbon MA-100, manufactured by Mitsubishi Chemical Corporation) having a DBP (dibutyl phthalate) oil absorption of 100 ml / 100 g dried at 100 ° C. for 2 hours is added to the mixture, and the ball mill is used for 1 hour ( 25 ° C.) well mixed. The composition of the obtained slurry liquid was 15% by weight of polyamic acid solid, 18.5% by weight of carbon black (based on solid content of polyamic acid), the other was the amount of solvent, and the solution viscosity was 800 cps (25 ° C.). It was.

  This was injected into the inner surface of a metal rotating drum (with a width of 400 mm and an inner diameter of 82 mm; a frame with a width of 20 mm on both sides) with a mirror finish on the inner surface, and the entire amount was injected. The rotation speed was gradually increased, and the rotation was continued at 340 times / minute for 30 minutes. Then, maintaining this state, the drum was heated to reach 180 ° C., and further rotated at that temperature for 80 minutes to evaporate the solvent and dry. As a result, a polyamic acid tubular seamless belt having a thickness of 50 ± 4 μm and a width of 380 mm was obtained in a semi-dry state. This was removed from the drum.

And the said polyamic-acid belt was covered with metal mandrels, all were put in a hot-air dryer, and it heated up gradually. First, when it reached 300 ° C., it was heated at that temperature for 20 minutes, and when it was further heated to reach 400 ° C., it was heated at that temperature for 20 minutes. By this heating, a polyimide belt having a thickness of 65 ± 5 μm, an inner diameter of 60 mm, and a width of 320 mm was obtained. The surface resistivity of the inner layer belt was 1 × 10 ⁷ (Ω / □).

  An ethylene / tetrafluoroethylene copolymer (Fluon LM-ETFE AH-2000, manufactured by Asahi Glass Co., Ltd.) was used with a φ40 single-screw extruder (cylinder temperature: 260 to 320 ° C.) with a circular die and an outer diameter of 53 mmφ, A cylindrical tube having a thickness of 55 ± 5 μm was formed.

Separately, a silicone release agent was applied as a release material to the outer peripheral surface of an aluminum cylindrical core having an outer diameter of 60 mm and a length of 400 mm, and baked at 380 ° C. for 1 hour. The cylindrical core was covered with the produced conductive polyimide belt and further covered with an ethylene / tetrafluoroethylene copolymer tube. This was baked in a heating furnace at 200 ° C. for 1 hour and then at 300 ° C. for 1 hour, whereby the tube was fusion-coated on the belt. Thereafter, the resin belt was removed from the core and cut to a width of 300 mm to produce an inkjet transport belt having a total film thickness of 120 μm (outer layer 55 μm, inner layer 65 μm) and inner layer surface resistivity 1 × 10 ⁷ (Ω / □).

Comparative Example 1
A polyamic acid solution obtained by polymerizing an equivalent of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine in N-methylpyrrolidone solvent at room temperature is further added to a solvent. N, N-dimethylacetamide was mixed and diluted. Next, carbon black (Mitsubishi Carbon MA-100, manufactured by Mitsubishi Chemical Co., Ltd.) having a DBP oil absorption of 100 ml / 100 g dried for 2 hours at 100 ° C. is added thereto, and the ball mill is sufficient for 1 hour (25 ° C.). Mixed. The composition of the resulting slurry liquid was 15% polyamic acid solid content, 18.0% carbon black (based on polyamic acid solid content), the other was the amount of solvent, and the solution viscosity was 800 cps (25 ° C.). It was.

  This was injected into the inner surface of a metal rotating drum (with a width of 400 mm and an inner diameter of 82 mm; a frame with a width of 20 mm on both sides) with a mirror finish on the inner surface, and the entire amount was injected. Thereafter, the rotation was gradually speeded up, and finally the rotation was continued at 340 times / minute for 30 minutes. While maintaining this state, the drum was heated to reach 150 ° C., and further rotated at that temperature for 80 minutes to evaporate the solvent and dry. As a result, a polyamic acid tubular seamless belt having a thickness of 50 ± 4 μm and a width of 380 mm was obtained in a semi-dry state. This was removed from the drum.

And the said polyamic-acid belt was covered with metal mandrels, all were put in a hot-air dryer, and it heated up gradually. First, when it reached 300 ° C., it was heated at that temperature for 20 minutes, and when it was further heated to reach 400 ° C., it was heated at that temperature for 20 minutes. By this heating, a polyimide belt having a thickness of 65 ± 5 μm, an inner diameter of 60 mm, and a width of 320 mm was obtained. The surface resistivity of the inner layer belt was 1 × 10 ⁷ (Ω / □).

  Polyvinylidene fluoride (KF polymer # 1000, manufactured by Kureha Co., Ltd.) was formed into a cylindrical shape having an outer diameter of 60 mmφ and a thickness of 55 μm ± 5 μm using a circular die using a φ40 mm single screw extruder (cylinder temperature: 180 to 230 ° C.). A tube was formed.

Separately, a silicone release agent was applied as a release material to the outer peripheral surface of an aluminum cylindrical core having an outer diameter of 60 mm and a length of 400 mm, and baked at 380 ° C. for 1 hour. This cylindrical core was covered with the produced conductive polyimide belt and further covered with a polyvinylidene fluoride tube. This was baked in a heating furnace at 100 ° C. for 1 hour and then at 200 ° C. for 1 hour, whereby the tube was fusion-coated on the belt. Thereafter, the resin belt was removed from the core and cut to a width of 300 mm to produce an inkjet transport belt having a total film thickness of 120 μm (outer layer 55 μm, inner layer 65 μm) and inner layer surface resistivity 1 × 10 ⁷ (Ω / □).

Comparative Example 2
Polyamide obtained by polymerizing an equivalent of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride and 4,4'-diaminodiphenyl ether (ODA) in N-methylpyrrolidone solvent at room temperature The acid solution was further mixed with a solvent N, N-dimethylacetamide and diluted. Next, carbon black (Mitsubishi Carbon MA-100, manufactured by Mitsubishi Chemical Co., Ltd.) having a DBP oil absorption of 100 ml / 100 g dried for 2 hours at 100 ° C. is added thereto, and the ball mill is sufficient for 1 hour (25 ° C.). Mixed. The composition of the obtained slurry liquid was 15% by weight of polyamic acid solid, 18.5% by weight of carbon black (based on solid content of polyamic acid), the other was the amount of solvent, and the solution viscosity was 800 cps (25 ° C.). It was.

  This was injected into the inner surface of a metal rotating drum (with a width of 400 mm and an inner diameter of 82 mm; a frame with a width of 20 mm on both sides) with a mirror finish on the inner surface, and the entire amount was injected. The rotation speed was gradually increased, and the rotation was continued at 340 times / minute for 30 minutes. Then, maintaining this state, the drum was heated to reach 180 ° C., and further rotated at that temperature for 80 minutes to evaporate the solvent and dry. As a result, a polyamic acid tubular seamless belt having a thickness of 50 ± 4 μm and a width of 380 mm was obtained in a semi-dry state. This was removed from the drum.

Then, the polyamic acid belt was fitted on a metal mandrel, and the whole was put in a hot air dryer and gradually heated. First, when it reached 300 ° C., it was heated at that temperature for 20 minutes, and when it was further heated to reach 400 ° C., it was heated at that temperature for 20 minutes. By this heating, a polyimide belt having a thickness of 65 ± 5 μm, an inner diameter of 60 mm, and a width of 320 mm was obtained. The surface resistivity of the inner layer belt was 1 × 10 ⁷ (Ω / □).

  A tetrafluoroethylene / hexafluoropropylene copolymer (hereinafter referred to as “FEP”) (neoflon FEP NP-21, manufactured by Daikin Industries, Ltd.) is used in a φ40 mm single screw extruder (cylinder temperature: 280 to 360 ° C.). A cylindrical tube having an outer diameter of 53 mmφ and a thickness of 55 μm ± 5 μm was formed using an annular die.

Separately, a silicone release agent was applied as a release material to the outer peripheral surface of an aluminum cylindrical core having an outer diameter of 60 mm and a length of 400 mm, and baked at 380 ° C. for 1 hour. This cylindrical core was covered with the produced conductive polyimide belt and further with an FEP tube. This was baked in a heating furnace at 200 ° C. for 1 hour and then at 300 ° C. for 1 hour, whereby the tube was fusion-coated on the belt. Thereafter, the resin belt was removed from the core and cut into a width of 300 mm to prepare an ink jet transport belt having a film thickness of 120 μm (outer layer 55 μm, inner layer 65 μm) and inner layer surface resistivity 1 × 10 ⁷ (Ω / □).

Comparative Example 3
A polyamic acid solution obtained by polymerizing an equivalent of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine in N-methylpyrrolidone solvent at room temperature is further added to a solvent. N, N-dimethylacetamide was mixed and diluted. Next, carbon black (Mitsubishi Carbon MA-100, manufactured by Mitsubishi Chemical Co., Ltd.) having a DBP oil absorption of 100 ml / 100 g dried for 2 hours at 100 ° C. is added thereto, and the ball mill is sufficient for 1 hour (25 ° C.). Mixed. The composition of the resulting slurry liquid was 15% polyamic acid solid content, 18.0% carbon black (based on polyamic acid solid content), the other was the amount of solvent, and the solution viscosity was 800 cps (25 ° C.). It was.

  This was injected into the inner surface of a metal rotating drum (with a width of 400 mm and an inner diameter of 82 mm; a frame with a width of 20 mm on both sides) with a mirror finish on the inner surface, and the entire amount was injected. The speed was gradually increased, and the rotation was continued at 340 times / minute for 30 minutes. While maintaining this state, the drum was heated to reach 150 ° C., and further rotated at that temperature for 80 minutes to evaporate the solvent and dry. As a result, a polyamic acid tubular seamless belt having a thickness of 50 ± 4 μm and a width of 380 mm was obtained in a semi-dry state. This was removed from the drum.

Then, the polyamic acid belt was fitted on a metal mandrel, and the whole was put in a hot air dryer and gradually heated. First, when it reached 300 ° C., it was heated at that temperature for 20 minutes, and when it was further heated to reach 400 ° C., it was heated at that temperature for 20 minutes. By this heating, a polyimide belt having a thickness of 65 ± 5 μm, an inner diameter of 60 mm, and a width of 320 mm was obtained.
The surface resistivity of the inner layer belt was 1 × 10 ⁷ (Ω / □).

  A tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (hereinafter referred to as “PFA”) (Teflon (registered trademark) 350J, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) is used in a φ40 single-screw extruder (cylinder temperature: 280 to 800). 420 ° C.) was used to form a cylindrical tube having an outer diameter of 53 mmφ and a thickness of 55 μm ± 5 μm with an annular die.

Separately, a silicone release agent was applied as a release material to the outer peripheral surface of an aluminum cylindrical core having an outer diameter of 60 mm and a length of 400 mm, and baked at 380 ° C. for 1 hour. This cylindrical core was covered with the produced conductive polyimide belt and further covered with a PFA tube. This was heat-sealed in a heating furnace at 300 ° C. for 4 hours. Thereafter, the resin belt was removed from the core and cut to a width of 300 mm to produce an inkjet transport belt having a total film thickness of 120 μm (outer layer 55 μm, inner layer 65 μm) and inner layer surface resistivity 1 × 10 ⁷ (Ω / □).

Comparative Example 4
In the same manner as in Example 1, a polyimide belt serving as an inner layer was obtained. The obtained polyimide belt had a thickness of 65 μ ± 5 μ, an inner diameter of 60 mm, and a width of 320 mm. Further, the surface resistivity of the belt was 1 × 10 ⁷ Ω / □.

  On the other hand, the polyimide tube used as an outer layer was created in the following manner. Cylindrical tube of outer diameter 60mmφ and thickness 55μm ± 5μm with a circular die using φ40 single screw extruder (cylinder temperature: 370-420 ° C) with thermoplastic polyimide (Aurum PL450C, manufactured by Mitsui Chemicals, Inc.) Was formed.

Separately, a silicone release agent was applied as a release material to the outer peripheral surface of an aluminum cylindrical core having an outer diameter of 60 mm and a length of 400 mm, and baked at 380 ° C. for 1 hour. This cylindrical core was covered with the produced conductive polyimide belt and further covered with a thermoplastic polyimide tube. This was heat-sealed in a heating furnace at 390 ° C. for 2 hours. Thereafter, the resin belt was removed from the core and cut to a width of 300 mm to produce an inkjet transport belt having a total film thickness of 120 μm (outer layer 55 μm, inner layer 65 μm) and inner layer surface resistivity 1 × 10 ⁷ (Ω / □).

Comparative Example 5
After blending 80% by weight of ethylene / tetrafluoroethylene copolymer (Fullon ETFE C-55AXB, manufactured by Asahi Glass Co., Ltd.) and 20% by weight of carbon black (Mitsubishi Carbon MA-100, manufactured by Mitsubishi Chemical Co., Ltd.), 2 The mixture was put into an axial screw extruder (cylinder temperature 295 to 340 ° C.) to produce a pellet raw material A.

This pellet-shaped raw material A was put into a 50 mmφ single-screw extruder for inner layer (cylinder temperature: 280 to 320 ° C.), and an ethylene / tetrafluoroethylene copolymer (Tefzel 290, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) A φ40 mmφ single-screw extruder for outer layer (cylinder temperature: 280 to 320 ° C.) was placed, and a circular mandrel die for two-layer extrusion was set at the tip of the discharge port where the two extruders joined. The die width of the die is adjusted for each of the outer layer and the inner layer, and co-extrusion molding is performed. The outer diameter is 60 mmφ, the total thickness is 150 ± 10 μm (the outer layer is 50 μm, the inner layer is 100 μm), and the inner layer surface resistivity is 1 × 10 ⁷ (Ω / □ ) Was prepared.

Comparative Example 6
A polyamic acid solution obtained by polymerizing an equivalent of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine in N-methylpyrrolidone solvent at room temperature is further added to a solvent. N, N-dimethylacetamide was mixed and diluted. Next, carbon black (Mitsubishi Carbon MA-100, manufactured by Mitsubishi Kasei Co., Ltd.) having a DBP (dibutyl phthalate) oil absorption of 100 ml / 100 g dried at 100 ° C. for 2 hours is added thereto, and the ball mill is used for 1 hour ( 25 ° C.) well mixed. The composition of the obtained slurry liquid was 15% by weight of polyamic acid solid, 14.0% by weight of carbon black (based on solid content of polyamic acid), the other was the amount of solvent, and the solution viscosity was 800 cps (25 ° C.). It was.

  This was injected into the inner surface of a metal rotating drum (with a width of 400 mm and an inner diameter of 82 mm; a frame with a width of 20 mm on both sides) with a mirror finish on the inner surface, and the entire amount was injected. The rotation speed was gradually increased, and the rotation was continued at 340 times / minute for 30 minutes. While maintaining this state, the drum was heated to reach 150 ° C., and further rotated at that temperature for 80 minutes to evaporate the solvent and dry. As a result, a polyamic acid tubular seamless belt having a thickness of 50 ± 4 μm and a width of 380 mm was obtained in a semi-dry state. This was removed from the drum.

And the said polyamic-acid belt was covered with metal mandrels, all were put in a hot-air dryer, and it heated up gradually. First, when it reached 300 ° C., it was heated at that temperature for 20 minutes, and when it was further heated to reach 400 ° C., it was heated at that temperature for 20 minutes. By this heating, a polyimide belt having a thickness of 65 ± 5 μm, an inner diameter of 60 mm, and a width of 320 mm was obtained. The surface resistivity of the inner layer belt was 2 × 10 ¹⁰ (Ω / □).

  An ethylene / tetrafluoroethylene copolymer (Tefzel 290, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was used with a circular die using a φ40 single screw extruder (cylinder temperature: 280 to 320 ° C.), thickness 55 A ± 5 μm cylindrical tube was formed.

Separately, a silicone release agent was applied as a release material to the outer peripheral surface of an aluminum cylindrical core having an outer diameter of 60 mm and a length of 400 mm, and baked at 380 ° C. for 1 hour. The cylindrical core was covered with the produced conductive polyimide belt and further covered with an ethylene / tetrafluoroethylene copolymer tube. This was baked in a heating furnace at 200 ° C. for 1 hour and then at 300 ° C. for 1 hour, whereby the tube was fusion-coated on the belt. Thereafter, the resin belt was removed from the core and cut into a width of 300 mm to produce an inkjet transport belt having a total film thickness of 120 μm (outer layer 55 μm, inner layer 65 μm) and inner layer surface resistivity 2 × 10 ¹⁰ (Ω / □).

Comparative Example 7
A polyamic acid solution obtained by polymerizing an equivalent of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and p-phenylenediamine in N-methylpyrrolidone solvent at room temperature is further added to a solvent. N, N-dimethylacetamide was mixed and diluted. Next, Ketchin Blackock EC (manufactured by Lion Co., Ltd.) having a DBP oil absorption of 360 ml / 100 g dried at 100 ° C. for 2 hours was added thereto, and mixed well for 1 hour (25 ° C.) with a ball mill. A liquid was obtained. The composition of the obtained slurry liquid is 13% (weight) of polyamic acid solid content, 8.0% (weight) of carbon black vs. solid content of polyamic acid, and the other is the amount of solvent, and the solution viscosity is 500 cps (25 ° C.). Met.

  This was injected into the inner surface of a metal rotating drum (with a width of 400 mm and an inner diameter of 82 mm; a frame with a width of 20 mm on both sides) with a mirror finish on the inner surface, and the entire amount was injected. The rotation speed was gradually increased, and the rotation was continued at 340 times / minute for 30 minutes. While maintaining this state, the drum was heated to reach 150 ° C., and further rotated at that temperature for 80 minutes to evaporate the solvent and dry. As a result, a polyamic acid tubular seamless belt having a thickness of 50 ± 4 μm and a width of 380 mm was obtained in a semi-dry state. This was removed from the drum.

And the said polyamic-acid belt was covered with metal mandrels, all were put in a hot-air dryer, and it heated up gradually. First, when it reached 300 ° C., it was heated at that temperature for 20 minutes, and when it was further heated to reach 400 ° C., it was heated at that temperature for 20 minutes. By this heating, a polyimide belt having a thickness of 65 ± 5 μm, an inner diameter of 60 mm, and a width of 320 mm was obtained. The surface resistivity of the inner layer belt was 5 × 10 ³ (Ω / □).

  An ethylene / tetrafluoroethylene copolymer (Tefzel 290, manufactured by Mitsui DuPont Fluorochemical Co., Ltd.) was used with a circular die using a φ40 single screw extruder (cylinder temperature: 280 to 320 ° C.), thickness 55 A ± 5 μm cylindrical tube was formed.

Separately, a silicone release agent was applied as a release material to the outer peripheral surface of an aluminum cylindrical core having an outer diameter of 60 mm and a length of 400 mm, and baked at 380 ° C. for 1 hour. The cylindrical core was covered with the produced conductive polyimide belt and further covered with an ethylene / tetrafluoroethylene copolymer tube. This was baked in a heating furnace at 200 ° C. for 1 hour and then at 300 ° C. for 1 hour, whereby the tube was fusion-coated on the belt. Thereafter, the resin belt was removed from the core and cut into a width of 300 mm to prepare an inkjet transport belt having a total film thickness of 120 μm (outer layer 55 μm, inner layer 65 μm) and inner layer surface resistivity 5 × 10 ³ (Ω / □).

Test example 1
For the inkjet transport belts obtained in the above examples and comparative examples, durability (flexibility), transportability, adsorptivity (dielectric constant), wear resistance, cleaning properties, and adsorptivity during operation of the transport belt Evaluation and belt surface contamination were evaluated. The results are shown in Tables 1 and 2. The evaluation method is as follows.
[Evaluation of durability]
In order to confirm the adhesion of the inner layer and the outer layer of the MIT test and to evaluate the crack of the belt, a bending resistance test was performed. If the bending resistance is low, the belt breaks from the belt end.

Equipment used: MIT testing machine manufactured by Toyo Seiki Seisakusho Co., Ltd. Measuring method: ASTM D-2176 compliant, bending angle 135 °, bending speed 175cpm, load 300g
The evaluation criteria are as follows.

MIT test count;
A: 30,000 or more B: 10,000 or more to less than 30,000 C: less than 10,000
When a conveyance belt having a high tensile elastic modulus is used, it is possible to suppress dimensional fluctuation due to a change in circumferential length due to stress and an environmental change when the belt is driven.

  The tensile elastic modulus was evaluated in accordance with JIS K-7127 (test speed 50 mm / min, 25 mm × 25 mm strip test piece) using an autograph manufactured by Shimadzu Corporation.

Tensile modulus;
A: 5.0 GPa or more B: 2.0 GPa or more and less than 5.0 GPa C: Less than 2.0 GPa [Evaluation of transportability (planarity)]
Since the conveyance of the paper under the environment of 26 ° C. is performed by electrostatic attraction, the flatness of the belt is necessary. If the unevenness is large, the contact area with the paper is reduced and the conveyance force is reduced, which may lead to an image defect. is there.

  The transportability (flatness) in a 26 ° C. environment was evaluated as follows. Two metal shafts of 30φ longer than the length in the width direction of the belt are passed through the belt, and both ends of the two metal shafts are arranged so as to protrude in the width direction of the belt. One shaft was fixed, and a 2.0 kg weight was attached to both ends of the other shaft to stretch the belt (see FIG. 1). In this state, the belt surface was scanned with a laser displacement meter (LK-030, manufactured by Keyence Co., Ltd.) attached in a direction perpendicular to the belt plane in an environment of 26 ° C., and the absolute value of the unevenness was measured. The evaluation criteria are as follows.

The absolute value of the unevenness;
A: 0.2 mm or less B: Over 0.2 mm to 0.3 mm or less C: Over 0.3 mm (causes adsorption failure)
Under the hot air at 80 ° C. Due to the recent increase in environmental awareness, water-based pigments and dye inks are mainly used as inks. However, since these inks are water-based, a drying process is required to improve the printing speed, and the belt needs heat resistance. If the heat resistance of the belt is low, deformation due to thermal expansion is caused and belt flatness is deteriorated. As a result, the adsorbability of the paper to the belt is inferior, resulting in poor conveyance and image defects.

  The transportability (flatness) under hot air at 80 ° C. was evaluated as follows. Two metal shafts of 30φ longer than the length in the width direction of the belt are passed through the belt, and both ends of the two metal shafts are arranged so as to protrude in the width direction of the belt. One shaft was fixed, and a 2.0 kg weight was attached to both ends of the other shaft to stretch the belt (see FIG. 1). In this state, after applying hot air of 80 ° C. from the vertical direction to the belt surface for 10 seconds, the belt surface was scanned with a laser displacement meter (LK-030, manufactured by Keyence Corporation) attached in the vertical direction, The degree of deterioration of the unevenness on the belt plane was measured as the absolute value of the unevenness.

Absolute value of unevenness (80 ° C under hot air);
A: 0.2 mm or less B: Over 0.2 mm to 0.3 mm or less C: Over 0.3 mm (causes adsorption failure)
[Evaluation of adsorptivity]
Since the sheet is electrostatically attracted, the larger the electrostatic capacity (C), the stronger the attracting force. The electrostatic attraction force is proportional to the electrostatic capacity, and the electrostatic capacity is proportional to the dielectric constant as shown in the following (formula 1).

C = εS / d
(C: capacitance {F}, ε: dielectric constant, S: area {m ² }, d: thickness {m}) (Formula 1)
Therefore, the higher the dielectric constant of the outer layer, the stronger the electrostatic adsorption force.

  The dielectric constant was measured using JIS K6911 mutual dielectric bridge method. The evaluation criteria are as follows.

Dielectric constant (23 ° C., 1 kHz);
A: 5.0 or more B: 2.5 or more and less than 5.0 C: less than 2.5 [Abrasion resistance evaluation]
When the belt has high wear resistance to the paper, the surface of the belt is less scraped and has a sufficient paper conveying force even during long-term operation.

The wear resistance was evaluated as follows. With the belt in close contact with A4 paper at a pressure of 0.2 kg / cm ² , the belt is slid 1000 times at 310 mm / sec in the longitudinal direction of the paper at 280 mm, and the belt weight difference before and after the slide is measured. The weight difference was defined as the amount of wear. The evaluation criteria are as follows.

Weight difference;
A: Less than 1 mg B: 1 mg or more and less than 5 mg C: 5 mg or more [Evaluation of ink cleaning properties]
If the ink cleaning property is inferior, the ink remains on the surface of the belt, causing a back-off to the paper, resulting in an image defect. From the viewpoint of cleaning properties, the belt surface must be highly releasable with respect to ink. The ink cleaning property was evaluated as follows.

  Using an ink cartridge LCO9BK (manufactured by Brother Industries, Ltd.), contact angles with respect to various outer layers were measured. The measurement device was a contact angle meter CA-S (manufactured by Kyowa Interface Chemical Co., Ltd.) and measured in an environment of 23 ° C. and 55% RH. The evaluation criteria are as follows.

Contact angle;
A: 60 ° or more B: Less than 60 °
[Evaluation during operation of conveyor belt]
Paper adsorption:
The ink-jet transport belts of the examples and comparative examples were mounted on an ink-jet image forming apparatus to form an image, and the paper adsorptivity to the surface of the ink-jet transport belt was observed to evaluate the paper adsorbability after printing 100 sheets. . The results are shown in Table 2 below. In the table, “A” means that the adsorptivity is sufficient, and “B” means that the adsorptivity is insufficient and peeling occurs.

Surface dirt:
The surface stain (ink residue, paper dust, back surface stain) after printing 100 sheets was affixed to a belt, and the stain was transferred to the tape to evaluate the surface stain. The results are shown in Table 2 below. In addition, "A" in the table means that there is almost no dirt even visually, "B" means that resin powder considered to be partial paper dust and outer layer scraping is seen, and "C" This means that ink stains can be seen on the entire surface of the tape.

Claims (12)

An inkjet transport belt comprising a multilayer seamless belt composed of at least two layers having an outer layer containing an ethylene / tetrafluoroethylene copolymer and an inner layer containing a conductive polyimide resin, wherein the outer layer has a thickness of 10 to 150 μm. Yes, an inkjet transport belt in which the surface resistivity of the inner layer is 1 × 10 ⁴ to 1 × 10 ⁹ (Ω / □). The inkjet conveyance belt according to claim 1, wherein the conductive polyimide resin contains a resin selected from the group consisting of thermoplastic polyimide, thermosetting polyimide, polyetherimide, and polyamideimide, and conductive carbon black. The inkjet transport belt according to claim 1 or 2, wherein an inner peripheral surface of the outer layer is chemically treated. The inkjet transport belt according to any one of claims 1 to 3, wherein the ethylene / tetrafluoroethylene copolymer contained in the outer layer exhibits absorption at 1720 to 1800 cm ^-1 by infrared spectroscopy. The inkjet transport belt according to any one of claims 1 to 4, wherein the ratio of the thickness of the outer layer to the inner layer (outer layer / inner layer) is 1/5 to 1/1. 6. The inkjet transport belt according to claim 1, wherein the outer layer (outer surface layer) has a surface resistivity of 10 ¹⁴ to 10 ¹⁷ (Ω / □). An ink jet recording apparatus comprising the ink jet transport belt according to claim 1. The ink jet recording apparatus according to claim 7, further comprising a mechanism for electrostatically attracting and transporting the recording medium to the ink jet transport belt according to claim 1. A method for producing an inkjet transport belt comprising a multilayer seamless belt,
(1) A step of producing a cylindrical belt (inner layer) made of a conductive polyimide resin by centrifugally molding a conductive polyamic acid solution;
(2) A step of producing a cylindrical belt (outer layer) by molding an ethylene / tetrafluoroethylene copolymer into a cylindrical shape by a molding method using melt extrusion, and (3) produced in (1) above. A process of fusing together the inner peripheral surface of the belt (outer layer) manufactured in (2) above to the outer peripheral surface of the belt (inner layer),
Manufacturing method. An inner layer surface resistivity is 1 × 10 ⁴ to 1 × 10 ⁹ (Ω / □) and an outer layer thickness is 10 to 150 μm .
(4) A production method including a step of co-extrusion molding so that a thermoplastic polyimide resin containing a conductive material is an inner layer and an ethylene / tetrafluoroethylene copolymer is an outer layer. An inner layer surface resistivity is 1 × 10 ⁴ to 1 × 10 ⁹ (Ω / □) and an outer layer thickness is 10 to 150 μm .
(5) A step of producing a cylindrical belt (inner layer) by molding a thermoplastic polyimide resin containing a conductive material into a cylindrical shape by a molding method using extrusion;
(6) A step of producing a cylindrical belt (outer layer) by molding an ethylene / tetrafluoroethylene copolymer into a cylindrical shape by a molding method using melt extrusion, and (7) produced in (5) above. A manufacturing method including a step of fitting the inner peripheral surface of the belt (outer layer) manufactured in the above (6) together with the outer peripheral surface of the belt (inner layer). The manufacturing method of Claim 9 whose surface resistivity of the inner layer of the said multilayer seamless belt is 1 * 10 < ⁴ > -1 * 10 < ⁹ > (ohm / square), and whose thickness of an outer layer is 10-150 micrometers.

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