JP5079629B2 - Method for producing polyimide composite tubular material and polyimide composite tubular material - Google Patents

Description

  The present invention relates to a method for producing a polyimide composite tubular product having a structure in which a silicone rubber layer is formed on the outer peripheral surface of a polyimide tubular product as a substrate, and a polyimide composite tubular product.

  Conventionally, due to its high mechanical strength and heat resistance, polyimide resin has been used for fixing belts, transfer belts, and intermediates in electrophotographic image forming apparatuses such as copying machines and laser beam printers that form images by electrophotography. It is used as a functional belt such as a transfer belt, a conveyance belt, and a photosensitive belt, and a base material thereof.

  In an electrophotographic image forming apparatus, a toner image formed on an image carrier such as a photosensitive member is directly transferred and fixed on a recording medium such as paper, or the toner image is transferred onto an intermediate transfer belt or the like. Once transferred to the body (primary transfer) (if a full-color image is formed, a toner image for each color is transferred), and then the toner image is transferred from the intermediate transfer body onto a recording medium such as paper (secondary transfer). However, in order to fix the toner image on the recording medium, a belt system that can increase the nip width so that the toner can be melted and fixed in a short time due to the demand for higher speed and higher image quality. The adoption of is increasing.

  That is, in a roll method in which a toner image on a recording medium is melted and fixed through a recording medium between a heating roll incorporating a heater and a pressure roll, a relatively long time is required until the surface of the heating roll is heated to a predetermined temperature. A belt system that melts and fixes the toner image on the recording medium through the recording medium between the fixing belt and the pressure roll, while the nip width (contact width between the heating roll and the pressure roll) cannot be increased. In this case, since the belt is thin and the heat capacity is small, the fixing operation can be performed immediately when the belt is heated, and since the contact width between the belt and the pressure roll is large, the toner can be fused and fixed in a short time.

  However, polyimide resin cannot be said to have high flexibility, and when used as a fixing belt, sufficient flexibility is not imparted to the belt, and it is necessary to improve flexibility from the viewpoint of high image quality. Therefore, in order to impart flexibility to the belt and further improve the releasability from the toner, a polyimide composite tubular material in which a rubber layer made of silicone rubber or fluororubber is provided on the outer peripheral surface of the polyimide tubular material has been proposed. (Patent Documents 1 to 4). That is, when such a polyimide composite tubular material having a rubber layer as an outer layer is used for a fixing belt, the rubber layer gives cushioning properties, and the toner image is crushed more than necessary because the belt softly contacts the toner image. It is possible to obtain a clear image because it is melt-fixed without any problem.

  However, in the research by the present inventors, a polyimide composite tubular material in which a rubber layer such as silicone rubber or fluororubber is provided on the outer peripheral surface of such a polyimide tubular material is used for the basic structure of a fixing belt. It turned out that the uniformity of thickness and the smoothness of the surface, which are the required properties, are reduced, and this is the reason why high image quality cannot be achieved at a higher level.

In Patent Document 5, a device having a slit head located outside the core body at a predetermined gap from the outer diameter of the core body is used, and polyimide or A method is disclosed in which a silicone rubber coating precursor solution is discharged while being controlled at a predetermined speed, and a coating of the precursor solution is cast on the outer surface of the core body with a predetermined film thickness. There is no description of a composite tubular product in which a silicone rubber layer is formed on the outer periphery of the product.
JP-A-5-305681 JP 2000-181257 A JP-A-10-161448 JP 2001-51535 A JP 2004-291367 A

  The present invention has been made in view of the above circumstances, and the problem to be solved is to provide a functional belt of an electrophotographic image forming apparatus, in particular, a cushioning property, which is useful as a fixing belt, and has a thickness. An object is to provide a polyimide composite tubular product having extremely good uniformity and surface smoothness and a method capable of producing the polyimide composite tubular product with high productivity.

In order to solve the above problems, the present invention adopts the following configuration.
(1) Extrapolating a polyimide tubular body to the outer periphery of the core body, and arranging an annular nozzle having a discharge opening having a certain clearance with respect to the outer peripheral surface of the polyimide tubular body, concentrically with the core body, and silicone rubber While discharging the solution from the annular nozzle to the outer peripheral surface of the polyimide tubular body at a predetermined discharge speed, the core and the annular nozzle are moved relative to each other to form a coating film of the silicone rubber solution on the outer peripheral surface of the polyimide tubular body. Thereafter, the polyimide tubular material is separated from the core, and the coating film on the outer peripheral surface of the polyimide tubular material after the separation is heated to form a silicone rubber layer, and a method for producing a polyimide composite tubular material .
(2) The method for producing a polyimide composite tubular article according to (1), wherein a fluororesin layer is further formed on the outer peripheral surface of the silicone rubber layer.
(3) The silicone rubber layer is formed by heating the coating film of the silicone rubber solution by two stages of heating, and the fluororesin liquid is formed on the outer peripheral surface of the primary cured layer formed from the coating film by the first stage heating. The production of a polyimide composite tubular article according to (2) above, wherein a coating film is formed and the second stage heating is performed to simultaneously form a silicone rubber layer (secondary cured layer) and a fluororesin layer. Method.
(4) A polyimide composite tubular material having a polyimide tubular material as a substrate and a silicone rubber layer laminated on the outer peripheral surface of the polyimide tubular material,
The silicone rubber layer is formed by heating and curing a coating film of a silicone rubber solution formed on the outer peripheral surface of a hollow polyimide tube that does not enclose a core, and is a polyimide composite Tubular object.
(5) A polyimide composite tubular product in which a fluororesin layer is further laminated on a silicone rubber layer,
The fluororesin layer is formed by heat-curing a fluororesin liquid coating film formed on a silicone rubber layer laminated on the outer peripheral surface of a hollow polyimide tubular product that does not enclose a core. The polyimide composite tubular article described in (4) above.

  According to the present invention, the annular nozzle disposed concentrically with the core body on which the polyimide tubular body is extrapolated is relatively moved between the core body and the annular nozzle while being discharged at a predetermined discharge speed onto the outer peripheral surface of the polyimide tubular body. Since the coating film of the silicone rubber solution is formed on the outer peripheral surface of the polyimide tubular material, the coating film (coating film) is always formed by a new silicone rubber solution, and the coating film (foreign matter or bubbles are not mixed) Film) can be formed. And after separating the polyimide tubular material from the core, the coating film (coating) of the silicone rubber solution is heat-cured, so that the thickness variation is small without being affected by thermal deformation, expansion, contraction, etc. of the core. In addition, a silicone rubber layer having excellent surface smoothness is formed. As a result, a polyimide composite tubular material having a cushioning property and a very uniform thickness and excellent surface smoothness is obtained which is useful as a fixing belt. be able to.

  Moreover, since the coating film (coating film) of the silicone rubber solution is formed by relatively moving the core body and the annular nozzle by the annular nozzle, the minimum amount necessary for the required length of the polyimide composite tubular product to be manufactured. Since it is sufficient to use a coating liquid (silicone rubber solution), a polyimide composite tubular product can be produced at low cost with little material loss.

  Further, in a mode in which a fluororesin layer is further laminated on the silicone rubber layer, the surface smoothness of the tubular product can be further improved, and a polyimide composite tubular product with further improved toner releasability can be obtained. In addition, the silicone rubber layer is formed by heating the coating film of the silicone rubber solution by two stages of heating, and the coating film of the fluororesin liquid is formed on the primary cured layer after the first stage heating. Adoption of a method of forming a silicone rubber layer (secondary cured layer) and a fluororesin layer simultaneously by heating at the stage improves the adhesion between the silicone rubber layer and the fluororesin layer, and mechanical strength, roundness, etc. In this respect, a more advantageous polyimide composite tubular product can be obtained.

Hereinafter, the present invention will be described in detail according to preferred embodiments.
The method for producing a polyimide composite tubular product of the present invention (hereinafter also abbreviated as the method of the present invention) is obtained by extrapolating a polyimide tubular product as a base material onto a core (that is, covering the outer periphery of the core with the polyimide tubular product). After forming a silicone rubber solution coating on the outer peripheral surface of the polyimide tubular body extrapolated to the core body, the polyimide tubular body is separated from the core body, and the coating film on the outer peripheral surface of the polyimide tubular body is heated. The procedure for forming the silicone rubber layer is then performed.

[Polyimide composite tube]
As the polyimide tubular material used as the base material, one produced by a known method can be used. When the polyimide composite tubular material is used for a functional belt such as a fixing belt of an electrophotographic image forming apparatus, a semiconductive polyimide tubular material containing a conductive substance may be used as the polyimide tubular material.

  As a method for producing a polyimide tubular product, for example, a polyimide precursor solution or a conductive substance-containing polyimide precursor solution is uniformly applied to the outer peripheral surface of a core (cylinder), converted into an imide, and then removed from the core. A method is mentioned. In this case, the polyimide precursor solution or conductive substance-containing polyimide precursor solution (hereinafter sometimes referred to as “precursor solution” in some cases) is applied to the outer peripheral surface of the core. A method in which the core body is dipped and pulled up, a method in which a precursor solution is supplied to the vicinity of one end of the core body, and a traveling body having a certain clearance is caused to travel, a hole having a certain clearance with the core body In addition, the precursor solution may be passed through a core supplied to the entire surface or a part thereof. The imide conversion of the polyimide precursor solution is usually performed by heating. As another method for producing a polyimide tubular product, as shown in FIG. 1, after the precursor solution 12 is spirally applied to the inner surface of a cylindrical mold 11, the coating is uniformly formed by rotational molding. An example is a method of developing, then drying to remove the solvent, and performing heat curing (reference numeral 13 in the figure is a coating nozzle for the polyimide precursor solution). This method is a preferable method because a polyimide tubular product that is particularly excellent in thickness uniformity is easily obtained.

  The polyimide precursor solution is prepared, for example, by polymerizing a tetracarboxylic dianhydride or derivative thereof and a diamine compound in an organic polar solvent. The tetracarboxylic dianhydride or derivative thereof and the diamine component are usually used in equimolar amounts.

  Specific examples of tetracarboxylic dianhydride include pyromellitic dianhydride (PMDA), 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′- Biphenyltetracarboxylic dianhydride (BPDA), 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5 , 6-Naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3 , 4-dicarboxyphenyl) sulfone dianhydride, berylene-3,4,9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylenetetracarboxylic Dianhydride and the like.

  Examples of the diamine include 4,4′-diaminodiphenyl ether (DDE), 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 3,3′-dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenylsulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine (PDA), 3,3′-dimethyl-4,4′-biphenyldiamine, benzidine, 3,3 ′ -Dimethylbenzidine, 3,3'-dimethoxybenzidine, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylpropane, 2,4-bis (β-amino-tert-butyl) toluene, bis (p- β-amino-tert-butylphenyl) ether, bis (p-β-methyl-6-amino) Phenyl) 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-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine 3 Methylheptamethylenediamine, 5-methylnonamethylenediamine, 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.

  As for said tetracarboxylic dianhydride and a diamine component, 1 type or 2 types or more can be used together.

  Examples of the organic polar solvent include N, N-dialkyl such as N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide and the like. In addition to amides, dimethyl sulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone (N-methylpyrrolidone (NMP)), pyridine, dimethyl sulfoxide, tetramethylene sulfone, dimethyl tetramethylene sulfone and the like can be mentioned. May be used alone or in combination of two or more.

The conductive substance is not particularly limited as long as it can impart conductivity, and for example, conductive powder such as carbon black, graphite, metal powder, an organic compound having conductivity, an inorganic compound, or the like is used. It is done. Such a conductive material is preferably used in an amount necessary to bring the surface resistivity of the polyimide tubular material to a range of 10 ¹ to 10 ⁸ Ω / □, and usually 0.5 to 50% by weight based on the polyimide. It is preferable to mix | blend so that it may exist in the range. In addition, the particle size of the conductive material is preferably at least the thickness (thickness) of the polyimide tubular material that is the base material in consideration of the surface smoothness of the obtained composite tubular material.

  The polyimide precursor solution can be obtained by reacting (polymerization reaction) the tetracarboxylic dianhydride or its derivative (a) and the diamine compound (b) for about 0.5 to 10 hours in an organic polar solvent. . In addition, reaction will become inadequate when it is less than 0.5 hour, and there exists a tendency for the effect beyond it not to be acquired even if it exceeds 10 hours. The monomer concentration during the reaction [concentration of (a) + (b) in the solvent] can be set according to various factors, but is usually 5 to 30% by weight. The reaction temperature is preferably set to 80 ° C. or lower. Especially, it is suitable to set reaction temperature to 5-50 degreeC.

  The viscosity of the resulting polyimide precursor solution increases due to polymerization, but when heated as it is, the viscosity of the polyimide precursor solution decreases. Using this phenomenon, the polyimide precursor solution can be adjusted to a predetermined viscosity. The heating temperature at this time is preferably 50 to 90 ° C.

  The conductive substance-containing polyimide precursor solution can be prepared by preparing a dispersion in which the conductive substance is dispersed in the solvent in advance, even in the method of dispersing the conductive substance in the polyimide precursor solution. A method may be used in which tetracarboxylic dianhydride or a derivative thereof and a diamine component are dissolved in a conductive material dispersion and polymerized.

  Imide conversion by heating the coating film of the polyimide precursor solution involves heating at a low temperature of about 80 to 180 ° C. to evaporate and remove the solvent, and then raising the temperature to about 250 to 400 ° C. to complete the imide conversion. It is preferable to use a multistage heating method. Although the time required for heating is appropriately set according to the heating temperature, it is usually about 20 to 60 minutes for both low temperature heating and subsequent high temperature heating. If such a multistage heating method is used, generation | occurrence | production of the microvoid in the polyimide tubular body resulting from ring-closing water and solvent evaporation which generate | occur | produce with imide conversion can be prevented.

  The operation of peeling the polyimide tubular body obtained by the imide conversion from the peripheral surface of the core body or the cylindrical mold is performed by, for example, providing a small through hole in advance in the wall of the core body or the cylindrical mold, and air in this hole. The polyimide tubular body can be peeled off from the core body or the cylindrical mold with the pressure; the method using a cylindrical mold whose surface has been subjected to a release treatment can be used.

  In the present invention, the thickness (layer thickness) of the polyimide tubular material as the base material is appropriately determined according to the specific application of the polyimide composite tubular material. When used for a belt, the thickness (layer thickness) of the polyimide tubular material is generally about 0.02 to 0.30 mm. In particular, in the case of a fixing belt, the thickness is 0.05 to 0.15 mm. The range is preferable. Further, the outer diameter is also appropriately determined according to the specific use of the polyimide composite tubular material. When the polyimide composite tubular material is used for a functional belt of an electrophotographic image forming apparatus, the diameter is about 10 to 1000 mm. In particular, in the case of a fixing belt, the diameter is preferably in the range of 30 to 300 mm.

[Extrapolation of polyimide tube to core]
In the method of the present invention, the polyimide tubular material is extrapolated to the core body, and a coating film of the silicone rubber solution is formed on the outer peripheral surface of the polyimide tubular object extrapolated to the core body. For example, it can be performed by inserting from the upper end of a pipe-shaped core body whose upper end portion is tapered. The core here is incorporated into a coating apparatus having an annular nozzle, which will be described later, and is usually a cylindrical body or a columnar body made of a material such as aluminum, stainless steel, rubber, or plastic. In addition, with respect to the outer diameter (diameter) of the core body, a predetermined clearance is required with respect to the inner diameter of the extrapolated polyimide tubular material from the viewpoint of preventing distortion of the extrapolated polyimide tubular material. The dimensional relationship is preferably such that the clearance is greater than 0 mm and 0.1 mm or less.

[Formation of silicone rubber layer]
FIG. 2A is a schematic view of an example of a coating apparatus having an annular nozzle used in the method of the present invention, and FIG. 2B is a schematic sectional view of the annular nozzle in FIG. FIG. 3 is a schematic cross-sectional view of an example of the polyimide composite tubular article of the present invention.

  In FIG. 2, 8 is a storage tank, 7 is a gear pump (extrusion pump), 6 is a mixing mixer, 4 is a coating film of a silicone rubber solution, and 9a and 9b are silicone rubber solutions (hereinafter simply referred to as “rubber solutions”). It is also called). The rubber solutions 9 a and 9 b are pumped to the mixing mixer 6 by a gear pump (extrusion pump) 7. In the mixing mixer 6, the rubber solution can be mixed by turbulently flowing the rubber solutions 9a and 9b. The mixed rubber solution is branched into the piping of the path by the branch unit 5 and guided to the annular nozzle 1. Although the branch unit 5 varies depending on the diameter of the polyimide composite tubular body on which the rubber layer is formed, a suitable number can be selected from 2 to 100 branches. If the number of branches is large, more precise discharge can be performed, but there is a problem of cost, and the range of 4 to 50 is preferable.

  The annular nozzle 1 is disposed concentrically with the core body 2, and the discharge port 1 a of the annular nozzle 1 is disposed with a certain clearance from the outer peripheral surface of the core body 2 (the outer peripheral surface of the polyimide tubular body 3). . At least one of the annular nozzle 1 and the core body 2 is configured to be movable in the axial direction of the core body 2 so that they move relative to each other in the axial direction of the core body 2. It is excellent in control accuracy for maintaining a constant separation distance (clearance) between the discharge port 1a and the outer peripheral surface of the core body 2 (the outer peripheral surface of the polyimide tubular body 3), and the structure for relative movement can be simplified. In many cases, the nozzle 1 is fixed and the core 2 is moved in the axial direction of the core 2.

  The discharge port 1a is formed over the entire circumference of the annular nozzle 1, and the solution is preferably supplied to the annular nozzle from one or more supply ports. The separation distance (clearance) between the discharge port 1a and the outer peripheral surface of the polyimide tubular body 3 is set according to the thickness of the silicone rubber layer to be formed, but is usually selected from the range of 0.05 mm to 3 mm. .

  In the method of the present invention, the extrusion speed of the silicone rubber solution in the gear pump 7 and the movement speed in the relative movement of the annular nozzle 1 and the core body 2 are controlled, and a predetermined amount of the rubber solution is extruded from the discharge port 1a of the annular nozzle 1. A coating film (coating film) 4 of rubber solutions 9a and 9b is formed on the outer peripheral surface of the polyimide tubular body 3 extrapolated to the core body 2 with a predetermined thickness. That is, the separation distance (clearance) between the discharge port 1a and the outer peripheral surface of the core body 2 (the outer peripheral surface of the polyimide tubular body 3) is set to a certain distance according to the thickness of the rubber layer to be formed. By adjusting the size of the discharge port 1a, the discharge speed of the rubber solution from the discharge port 1a (the push rate of the rubber solution of the gear pump 7), and the moving speed of the relative movement of the annular nozzle 1 and the core body 2, the rubber is adjusted. The coating film (film) 4 of the solution can be formed with high accuracy to a predetermined thickness.

  For example, when manufacturing a composite tubular product for a fixing belt in an electrophotographic image forming apparatus, the thickness of the rubber layer provided on the outer peripheral surface of the polyimide tubular product is generally about 100 to 400 μm. When the layer is formed, the discharge amount of the rubber solution from the discharge port 1a of the annular nozzle 1 is selected from a range of 1 to 200 g / min. The moving speed in the relative movement is preferably selected from the range of 100 to 5000 mm / min. Here, the moving speed by the relative movement of the annular nozzle 1 and the core body 2 indicates the magnitude of the relative speed of both. For example, in the embodiment in which the core body 2 is moved at 500 mm / min in one axial direction of the core body 2 and the annular nozzle 1 is moved at 100 mm / min in the other axial direction, the moving speed by relative movement Is 600 mm / min, and in the embodiment in which the core body 2 is moved in the direction of one axis of the core body 2 at 800 mm / min and the annular nozzle 1 is stationary, the moving speed by relative movement is 800 mm / min. It is.

  Further, it is preferable that the rubber solution is discharged in a larger amount per unit time than 0% by weight and 50% by weight or less than the minimum amount required for film formation. More preferably, a large amount is discharged in a range of more than 5% by weight and 30% by weight or less per unit time from the minimum amount required for film forming. If you do not discharge more than the minimum amount required for film forming, the film may be blurred or uneven, and if you discharge more than 50% by weight more than the minimum amount required for film forming, the film thickness is required. It becomes larger than the above, which is not preferable.

  Before the silicone rubber solution is discharged from the annular nozzle and a coating film (film) of the silicone rubber solution is formed on the outer peripheral surface of the polyimide tubular product, the surface of the polyimide tubular product is coated with a silicone rubber solution as necessary. You may apply | coat the primer for improving the adhesiveness of a film | membrane (coat) and this tubular thing. The primer is not limited as long as the effect of the present invention is not impaired.

  Although the silicone rubber used in the present invention is not particularly limited, a liquid rubber is preferably used, and examples thereof include silicone rubber such as a commercially available thermosetting silicone rubber (silicone RTV rubber). . The liquid silicone rubber can be adjusted in viscosity by adding a solvent and a viscosity modifier. As the viscosity modifier, toluene or the like can be used. The “silicone rubber solution” as used in the present invention is a concept that includes liquid silicone rubber that exhibits a liquid state without containing a solvent, and is a general term for liquid materials that can be applied with silicone rubber as a main component. is there. Further, the silicone rubber layer in the present invention may contain silicone-based or fluorine-based organic compounds, coupling agents, lubricants, antioxidants, and other additives to the extent that the physical properties are not impaired. When such an additive is contained in the silicone rubber layer, an appropriate amount of these additives is added to the silicone rubber solution.

  After forming the coating film (film) 4 of the rubber solution using the coating apparatus having the annular nozzle, the core body 2 and the polyimide tubular body 3 are separated, and the coating film on the outer peripheral surface of the polyimide tubular body 3 (Coating) 4 is heated to form a silicone rubber layer, and the target composite tubular product is completed. Separation here can be performed by a method in which a small through-hole is provided in advance in the wall of the core body, air is pumped into the hole, and the polyimide tubular body is peeled off from the core body by the pressure.

  In the present invention, as described above, the coating film (film) 4 is heated in a state where the polyimide tubular product 3 is separated from the core body 2. The heating at this time is preferably in the temperature range of 50 to 200 ° C., and primary vulcanization (primary curing) and secondary vulcanization (post vulcanization, secondary curing) are performed by two-stage heating. Is preferred. Specifically, the tubular product is heated for about 1 to 30 minutes at a temperature of 60 to 200 ° C. for primary vulcanization, and then heated at 320 to 450 ° C. for about 5 to 60 minutes for secondary vulcanization. Is mentioned. The silicone rubber solution coating (film) 4 formed on the outer peripheral surface of the polyimide tubular body 3 in a state where the polyimide tubular body 3 is separated from the core body 2 is heat-cured, so that the core body 2 is thermally deformed and expanded. The silicone rubber layer 10 is formed by drying and curing without being affected by shrinkage or the like (see FIG. 3). Since the silicone rubber layer does not shrink while being cured, the thickness uniformity and A rubber layer having high surface smoothness is formed. Specifically, for example, when a composite tubular product having an outer diameter of 20 to 1000 mm and a length of 100 to 1000 mm is produced, the thickness variation is within ± 10% (preferably within ± 5%). Can be suppressed. Further, the surface smoothness of the surface is suppressed to 1 μm or less (preferably 0.5 μm or less).

  Here, the “thickness variation” is a variation in the total thickness of the polyimide tubular body on which the silicone rubber layer is formed, and using a micrometer or the like, four points in the circumferential direction (90 ° intervals), the length direction It can be obtained from the measurement value of the total thickness at intervals of 50 mm, and represents the percentage of the difference between each measurement value and the approximate average value with respect to the approximate average value of the total thickness measurement value as a percentage. The thickness of the silicone rubber layer is also a measured value of the total thickness of the polyimide tubular body on which the silicone rubber layer is formed, using a micrometer or the like at four points in the circumferential direction (90 ° intervals) and at intervals of 50 mm in the length direction. From this, it can be obtained by subtracting the measured value of the thickness at the same measurement point of the polyimide tubular body before forming the silicone rubber layer.

  “Surface roughness” is a measured value of Ra (center line average roughness) of the outer surface of the silicone rubber layer, and is measured by, for example, a surface roughness measuring device (manufactured by Tokyo Seimitsu Co., Ltd., Surfcom 550A, etc.). be able to.

[Formation of fluororesin layer]
In the present invention, a fluororesin layer can be further formed on the outer peripheral surface of the silicone rubber layer formed as described above in order to further improve the releasability of the polyimide composite tubular product with respect to the toner.

  Examples of fluororesins include tetrafluoroethylene resin (PTEF), tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), and trifluoride chloride. An ethylene resin (PCTFE) or the like is suitable, and a conductive fluororesin containing a conductive material such as carbon or metal can be used for the fluororesin layer. In addition, in the said fluororesin layer, powder, such as a silica, silicon carbide, a glass bead, crosslinked silicone resin, a polyimide resin, a benzoquaamine resin, can be disperse | distributed and abrasion resistance can be improved. Moreover, the electroconductive substance mix | blended with the above-mentioned polyimide tubular body can also be mix | blended. The thickness of the fluororesin layer is generally in the range of 1 to 50 μm, preferably in the range of 5 to 30 μm, from the viewpoints of wear resistance and film formability of the fluororesin layer.

  The fluororesin layer is formed by using a fluororesin-containing liquid such as a resin solution obtained by dissolving a fluororesin in an appropriate organic solvent, a dispersion obtained by dispersing fluororesin particles in water, an organic solvent, or a mixed solvent thereof. It can be formed by coating the surface by spraying, dipping or the like and heating (curing) the resulting coating film. Additives blended into the fluororesin layer as necessary can be blended in the coating liquid at the preparation stage of the coating liquid. In addition, the fluororesin solution can be used as it is, or diluted with water or an organic solvent.

  The heating temperature of the coating film formed from the fluororesin liquid is not particularly limited, but is generally about 320 to 450 ° C. Usually, the fluororesin is cured (baked) if heated for about 5 to 60 minutes. Thus, a fluororesin layer is obtained. Further, the silicone rubber layer is formed by two-step heating of the coating film of the above-mentioned silicone rubber solution, and the first vulcanization (primary curing) of the silicone rubber obtained by the first-stage heating is performed. By forming a coating film of the fluororesin liquid on the outer peripheral surface of the secondary cured layer, the secondary curing of the silicone rubber layer and the curing (firing) of the fluororesin are simultaneously performed by the second heating, and the silicone rubber layer A fluororesin layer can also be formed thereon. By simultaneously forming the silicone rubber layer and the fluororesin layer, the adhesion between the silicone rubber layer and the fluororesin layer is improved, and a polyimide composite tubular product that is more advantageous in terms of mechanical strength, roundness, and the like is obtained. be able to.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

Example 1
N-methyl-2-pyrrolidone (786.9 g) was mixed with carbon black (MA-100 manufactured by Mitsubishi Chemical Corporation) (30.0 g) with a ball mill at room temperature (25 ° C.) for 12 hours. To the obtained carbon black dispersion, 133.9 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 49.2 g of p-phenylenediamine (PDA) were added at room temperature (25 ° C.). And polymerized. The carbon black-dispersed polyimide precursor having a viscosity of 150 Pa · s is obtained by stirring the solution thickened by the polymerization reaction at 60 ° C. with a three-one motor (manufactured by Shinto Kagaku Co., Ltd., FBL300) for 18 hours at a rotation speed of 5 rpm. A solution was obtained.

  This solution was applied to the inner peripheral surface of a drum mold having an inner diameter of 68 mm and a length of 500 mm while rotating the mold through an application nozzle, and the mold was rotated at 1500 rpm for 10 minutes to obtain a thickness. A uniform spread layer of about 500 μm was obtained. It was heated for 30 minutes while rotating the drum mold at 250 rpm in a drying oven at 150 ° C. in which hot air was circulated uniformly. Further, while rotating the mold, the temperature was raised to 350 ° C. at a rate of 2 ° C./min, and heating was continued for 30 minutes as it was to proceed with imidization. After cooling to room temperature, it was peeled from the inner surface of the mold to obtain a polyimide tubular product having a thickness of 75 μm.

  A polyimide tube was attached to the outer periphery of a cylindrical core body made of aluminum having an outer diameter of 67.8 mm and a length of 600 mm. A primer (silicone solution manufactured by Toray Dow Corning, product name DOW CORNING TORAY DY 39-067) was brushed on the outer surface, and dried at 150 ° C. for 5 minutes. In the annular applicator shown in FIG. 2, an annular nozzle having an inner diameter of 68.6 mm and a clearance of 0.2 mm having a discharge opening with a nozzle opening width of 1.0 mm is installed, followed by silicone rubber (DOW CORNING TORAY DY, manufactured by Toray Dow Corning). 35-2083 A and B) 2 liquids were put into storage tanks. The two liquids were fed to an annular nozzle while being mixed with a mixing mixer at a ratio of 1: 1 by an extrusion pump (manufactured by Japan Labor Responsible Technology Laboratory, MGP-X030). Thereafter, the extrusion speed of the extrusion pump and the rising speed of the core body are controlled while the annular nozzle is kept stationary (extrusion scale of the extrusion pump: 230, rising speed of the core body: 1000 mm / min), and a predetermined amount from the annular nozzle. The silicone rubber solution was extruded (discharge amount: 43.5 g / min), and a silicone rubber film was formed to a thickness of 200 μm on the outer surface of the polyimide tube. The core body was removed from the annular coating device together with the polyimide tubular body on which the silicone rubber coating was formed, and the core body and the tubular body were separated. Thereafter, the tubular product was heated at 150 ° C. for 5 minutes for primary vulcanization to obtain a tubular product having a silicone rubber formed on the outer surface of the polyimide tubular product with a thickness of 200 μm. Furthermore, a fluororesin (Mitsui / DuPont Fluoro Chemical Co., Ltd., EM-560CL, chemical name: PFA (perfluoroethylene propylene copolymer)) is coated on the outer surface of the silicone rubber as a release layer by a spray coating method. Formed and heated at 350 ° C. for 30 minutes to perform post vulcanization (secondary vulcanization) of silicone rubber and baking of fluororesin, and a composite tubular product having a three-layer structure of polyimide / silicone rubber / fluororesin ( An inner diameter of 68 mm and an average tube wall thickness of 285 μm) were obtained.

  Similar to the measurement method described above, the thickness of the silicone rubber layer, the fluctuation value of the thickness of the two-layered tubular material on which the silicone rubber layer is formed, and the tube of the three-layered composite tubular material are measured using the above-described apparatus. When the wall thickness and its fluctuation value, and the surface roughness of the composite tubular material were measured, the thickness of the silicone rubber layer was 188 to 208 μm, and the fluctuation value of the thickness of the two-layered tubular material on which the silicone rubber layer was formed The tube wall thickness of the composite tubular article having a three-layer structure was -6% to + 4%, and the variation value of the thickness was -6% to + 4%. The surface roughness of the outer surface of the fluororesin layer was 0.16 μm.

This three-layered composite tubular material is cut into a length of 350 mm while maintaining the tube shape, and is mounted as a fixing belt on a fixing unit of a laser printer (manufactured by Hewlett-Packard Japan, HP3500) to produce a color image. An image was obtained and evaluated. Evaluation of image quality
5: There are no defects such as fixing unevenness, and the image is very good and clear.
4: There are no defects such as uneven fixing, and the image is good and clear.
3: There are no defects such as uneven fixing, and the image is good, but it is not very clear.
2: There are no problems such as uneven fixing, but the image is not clear.
1: Problems such as fixing unevenness are observed.
The five steps were performed. As a result, the evaluation was 5, and an extremely clear and good image with no fixing unevenness could be obtained.

Comparative Example 1
A polyimide tubular product (thickness 75 mm, inner diameter 68 mm, length 500 mm) obtained by the same method as in Example 1 is extrapolated to a cylindrical core (outer diameter 67.8 mm), The same silicone rubber solution as No. 1 (made by Toray Dow Corning, DOW CORNING TORAY DY 35-2083 A and B) was applied in a spiral shape. The spiral application is the same as the method of applying the polyimide precursor solution to the inner surface of the cylindrical mold shown in FIG. 1 via the application nozzle, and the outer peripheral surface of the polyimide tubular material via the application nozzle. The coating was performed by arranging an application nozzle so that the silicone rubber solution was applied, and a silicone rubber layer was formed on the outer surface of the polyimide tubular product with a thickness of about 200 μm. As a result, the obtained two-layered composite tubular article has irregularities formed on the silicone rubber coating so that it can be seen visually, and is clearly unsuitable as a fixing belt. It was shown that it cannot be used as a method for obtaining a polyimide composite tubular article having a good thickness uniformity and surface smoothness for use as a belt.

It is a figure which shows typically the film forming process of a polyimide tubular product. It is a figure which shows typically the cyclic | annular coating apparatus used by this invention. It is a cross-sectional schematic diagram of an example of the polyimide composite tubular article of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ring nozzle 1a Discharge port 2 Core body 3 Polyimide tubular material 4 Coating film (film)
5 Branch unit 6 Mixing mixer 7 Gear pump (extrusion pump)
8 Storage tank 9a, 9b Silicone rubber solution 10 Silicone rubber layer 11 Cylindrical mold 12 Precursor solution 13 Coating nozzle

Claims (3)

  A polyimide tubular product is extrapolated to the outer periphery of the core body, an annular nozzle having a discharge port having a certain clearance with respect to the outer peripheral surface of the polyimide tubular body is disposed concentrically with the core body, and the silicone rubber solution is While discharging at a predetermined discharge speed from the annular nozzle to the outer peripheral surface of the polyimide tubular product, the core and the annular nozzle are moved relative to each other to form a coating film of the silicone rubber solution on the outer peripheral surface of the polyimide tubular product, A method for producing a polyimide composite tubular product, comprising separating a polyimide tubular product from a core and heating a coating film on an outer peripheral surface of the polyimide tubular product after the separation to form a silicone rubber layer.   2. The method for producing a polyimide composite tubular article according to claim 1, wherein a fluororesin layer is further formed on the outer peripheral surface of the silicone rubber layer. A silicone rubber layer is formed by heating the coating film of the silicone rubber solution by two stages of heating, and a coating film of a fluororesin liquid is formed on the outer peripheral surface of the primary cured layer formed from the coating film by the first stage heating. The method for producing a polyimide composite tubular article according to claim 2, wherein the silicone rubber layer (secondary cured layer) and the fluororesin layer are formed simultaneously by forming and heating in the second stage .

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