JP2005262729A - Seamless belt and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyimide-based seamless belt centrifugally molded in a cylindrical mold, wherein a surface roughness of an inner surface of the belt is controlled and/or wherein functional particles dispersed in the belt are localized on the side of the inner surface of the belt, and a manufacturing method for the seamless belt. <P>SOLUTION: The seamless belt, which comprises at least a polyimide resin layer constituted by being centrifugally molded in the cylindrical mold, is characterized in that the side of a surface, brought into noncontact with the mold, of the polyimide resin layer is an outer surface of the belt. In the seamless belt, the polyimide resin layer contains the functional particles, and the functional particles are dispersed in the state of leaning to the side of the inner surface of the belt in the thickness direction of the layer. The manufacturing method for the seamless belt comprises: a step of forming the polyimide resin layer by centrifugally molding it in the mold; a step of obtaining the seamless belt having at least the formed polyimide resin layer; and a step of reversing the obtained seamless belt. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a laser beam printer, and a facsimile machine, a seamless belt used for heat sealing, and the like, and a manufacturing method thereof.

  In an apparatus for forming and recording an image by an electrophotographic method such as a copying machine, a laser printer, a video printer, a facsimile machine, or a composite machine thereof, recording toner or the like on an image carrier such as a photosensitive drum for the purpose of improving the life of the apparatus. A method has been examined in which an image formed on an image carrier is temporarily transferred to an intermediate transfer belt and fixed on a printing sheet by avoiding a method of directly fixing an image formed via an agent on the printing sheet. . Further, for the purpose of downsizing the apparatus, a method in which the intermediate transfer belt also serves as toner fixing has been studied.

As a semiconductive belt that can be used for the intermediate transfer belt, one having a volume resistivity of 1 to 10 ¹³ Ω · cm by blending a polyimide film with a conductive filler is known (see Patent Document 1). . In order to manufacture such a belt, conventionally, a method of centrifugally molding a thermosetting polyimide resin in a cylindrical mold has been adopted, but it is possible to change the surface roughness of the belt inner surface for driving. What is difficult is that, in intermediate transfer belt applications, conductive fine particles are localized on the mold surface side (belt outer surface) due to centrifugal force, and the originally desired high surface resistivity and low volume resistivity We had problems such as having a reverse slope. On the other hand, a method of laminating multiple layers on the outer surface of the mold to produce a seamless belt is also employed, but there is a problem that centrifugal molding cannot be applied and thickness variation is large.
JP-A-5-77252

  Accordingly, an object of the present invention is to provide a polyimide seamless belt that is centrifugally molded in a cylindrical mold, in which the surface roughness of the inner surface of the belt is controlled and / or the functional particles dispersed in the belt are on the inner surface side of the belt. It is to provide a seamless belt and a method for manufacturing the same.

  As a result of intensive research to solve the above problems, the present inventor has found that a seamless belt having characteristics satisfying the following conditions is obtained, and has completed the present invention.

  That is, the seamless belt of the present invention is a seamless belt having at least a polyimide resin layer formed by centrifugal molding in a cylindrical mold, and the die non-contact surface side of the polyimide resin layer is an outer surface of the belt. It is characterized by.

  It is preferable that the polyimide resin layer contains functional particles, and the functional particles are inclined and dispersed on the belt inner surface side in the thickness direction of the layer.

  The surface roughness Rz of the inner surface of the seamless belt is preferably 0.2 μm to 3.0 μm, and more preferably 0.6 to 2.0 μm for use as a driving belt.

  Moreover, the seamless belt which consists of a multilayer formed by further laminating | stacking on the said polyimide resin layer within the said cylindrical metal mold | die is preferable.

  The method for producing a seamless belt of the present invention includes a step of forming a polyimide resin layer by centrifugal molding in a cylindrical mold, a step of obtaining a seamless belt having at least the formed polyimide resin layer, and the obtained seamless belt Including a step of inverting.

  When the seamless belt is composed of multiple layers, the step of obtaining the seamless belt is a step of obtaining a multilayer seamless belt by further laminating the formed polyimide resin layer by centrifugal molding in the cylindrical mold. Preferably there is.

  In the seamless belt of the present invention, the contact surface side with the mold is the inner surface of the belt, and the non-contact surface side is the outer surface of the belt. Therefore, the surface roughness of the belt inner surface can be freely designed by the surface treatment of the mold. . As a result, in addition to being used as an intermediate transfer belt, drive control is facilitated, and it is suitable as a drive belt. Needless to say, the thickness of the entire belt is well controlled by centrifugal molding.

  In the seamless belt of the present invention, when conductive particles are used as functional particles and used in an intermediate transfer belt of an electrophotographic apparatus, the conductive particles are localized on the inner surface of the belt, so that the surface resistivity is relatively low. Since the volume resistivity is small, the transfer property is excellent even at a small voltage, and it can contribute to energy saving of the apparatus itself.

  Furthermore, when the seamless belt of the present invention has a multilayer structure, it is different from a spray-coated belt, etc. if a release layer such as fluororesin or silicone rubber is provided by centrifugal molding in a cylindrical mold. Thus, a release layer having a smooth surface can be obtained, and a seamless belt excellent as a release belt for heat sealing or the like can be provided.

  According to the seamless belt manufacturing method of the present invention, the seamless belt can be efficiently manufactured by inverting the obtained seamless belt. In addition, according to the manufacturing method of the present invention, even when a multilayer is formed, all the coating is performed on the inner surface of the mold, so that a large-diameter belt can be easily manufactured without requiring large-scale equipment.

  The base of the seamless belt of the present invention is obtained by applying a corresponding polyamic acid solution to the inner surface of a cylindrical mold (preferably subjected to a mold release treatment), centrifugally molding, and then heating to remove the solvent and dehydrate it. It is obtained by removing the ring-closing water and converting the imide, cooling it to room temperature and peeling it from the mold. The desired seamless belt is obtained by reversing the seamless belt as the base.

  In the present invention, the polyamic acid solution is obtained by reacting approximately equimolar amounts of tetracarboxylic dianhydride or its derivative and diamine in an organic polar solvent.

  Specific examples of the tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4′- Biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalene Tetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,2′-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-di Carboxyphenyl) sulfone dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, ethylenetetracarboxylic dianhydride, etc. It is.

  Specific examples of diamines to be reacted with such tetracarboxylic dianhydrides include 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, and 3,3′-. Dichlorobenzidine, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfone, 1,5-diaminonaphthalene, m-phenylenediamine, p-phenylenediamine, 3,3′-dimethyl-4,4′- Biphenyldiamine, benzidine, 3,3′-dimethylbenzidine, 3,3′-dimethoxybenzidine, 4,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfide, 4,4′-diaminodiphenylpropane, 2, 4-bis (β-amino-tert-butyl) toluene, bis (p -Β-amino-t-butylphenyl) ether, bis (p-β-methyl-δ-aminophenyl) benzene, bis-p- (1,1-dimethyl-5-amino-pentyl) benzene, 1-isopropyl- 2,4-m-phenylenediamine, m-xylylenediamine, p-xylylenediamine, di (p-aminocyclohexyl) methane, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, Diaminopropyltetramethylene, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-diaminododecane, 1,2-bis-3-aminopropoxyethane, 2,2-dimethylpropylenediamine, 3 -Methoxyhexamethylenediamine, 2,5-di Tylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methylnonamethylenediamine, 2,11-diaminododecane, 2,17-diaminoeicosadecane, 1,4-diamino Examples include cyclohexane, 1,10-diamino-1,10-dimethyldecane, 1,12-diaminooctadecane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, and piperazine.

  One or more of these tetracarboxylic dianhydrides or their derivatives and diamines can be appropriately selected and reacted.

  The organic polar solvent used when the tetracarboxylic dianhydride and diamine are reacted has a dipole whose functional group does not react with tetracarboxylic dianhydride or diamine. It must be inert to the system and act as a solvent for the product polyamic acid. Moreover, it must act as a solvent for at least one of the reaction components, preferably both.

  As the organic polar solvent, N, N-dialkylamides are particularly useful, and examples thereof include N, N-dimethylformamide and N, N-dimethylacetamide, which have low molecular weight. They can be easily removed from the polyamic acid and the polyamic acid molded article by evaporation, displacement or diffusion. Other organic polar solvents include N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethylsulfoxide, hexamethylphosphortriamide, N-methyl-2-pyrrolidone, pyridine , Tetramethylene sulfone, dimethyltetramethylene sulfone and the like. These may be used alone or in combination. Furthermore, phenols such as cresol, phenol and xylenol, benzonitrile, dioxane, butyrolactone, xylene, cyclohexane, hexane, benzene, toluene and the like can be mixed alone or in combination with the organic polar solvent. However, it is preferable to avoid the use of water in order to prevent lowering the molecular weight due to hydrolysis of the produced polyamic acid.

  A polyamic acid solution is obtained by reacting the above tetracarboxylic dianhydride and diamine in an organic polar solvent.

  The reaction temperature is preferably set to 80 ° C. or less, particularly preferably 5 to 50 ° C., and the reaction time is about 0.5 to 10 hours.

  Thus, the polyamic acid is produced by reacting the acid dianhydride component raw material and the diamine component raw material in an organic polar solvent, and the solution viscosity increases as the reaction proceeds. When such a polyamic acid solution has a high viscosity, it is diluted with an appropriate solvent to lower the viscosity.

  For example, the viscosity of the polyamic acid solution is set according to the coating thickness, the inner diameter of the cylindrical mold, the solution temperature, etc., but is usually 1 to 1000 Pa · s (the temperature at the time of the coating operation, with a B-type viscometer. Measured value).

  In addition, the polyamic acid concentration in the polyamic acid solution is preferably set to 5 to 30% by weight, particularly preferably 10 to 20% by weight, from the viewpoint of effects.

  In order to add a function to the seamless belt according to the present invention, functional particles can be contained in the polyamic acid solution.

  Although it does not specifically limit as a functional particle, A heat conductive and / or electroconductive particle is illustrated. Specifically, the thermally conductive particles include boron nitride powder, alumina powder, beryllium oxide powder, silicon carbide powder, potassium titanate powder, aluminum nitride powder, mica, silica powder, titanium oxide powder, talc, calcium carbonate powder. Etc. For the conductive particles, carbon such as carbon black and graft carbon; powders of various metals such as aluminum, silver and copper can be used. Note that most of these conductive particles have thermal conductivity, and they become thermal conductive and conductive particles.

  Examples of other functional particles include fluororesin powder for imparting lubricity. Specifically, the fluororesin powder includes polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoroethylene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), ethylene. -Tetrafluoroethylene copolymer (ETFE) etc. are mentioned. Especially, use of PTFE excellent in heat resistance is preferable.

  The functional particles can be dispersed in the organic polar solvent at any stage of preparing the polyamic acid solution. As a dispersion method, a known dispersion method such as a ball mill, a sand mill, or ultrasonic dispersion can be used.

  In the present invention, the functional particles are preferably inclined and dispersed on the belt inner surface side in the thickness direction of the polyimide resin layer. Inclination and dispersion can be performed by adjusting the number of rotations for centrifugal molding in consideration of the viscosity of the polyamic acid solution, the specific gravity of the functional particles, the thickness of the polyimide resin layer to be formed, and the like. When conductive particles are used as the functional particles, the conductive particles are localized on the inner surface side of the obtained seamless belt, the surface resistivity is higher on the belt inner surface than the belt surface, and the surface resistivity of the belt surface Since the volume resistivity is relatively small as compared with the above, it is suitable as a transfer belt.

  When functional particles are used for the intermediate transfer belt, carbon black is preferably used as the conductive particles in order to make the polyimide resin semiconductive. As the carbon black, ketjen black, acetylene black and furnace black are suitably used, and the content thereof needs to show a predetermined resistance in the range of 5 to 30% by weight with respect to the polyimide resin solid content. is there. Particularly preferably, it is in the range of 5 to 25% by weight. If the carbon black content is less than 5% by weight, the conductivity becomes too low and the volume resistance becomes so high that the desired resistance cannot be obtained. On the other hand, if it exceeds 30% by weight, the seamless belt obtained thereby is not preferable because it has low mechanical strength and is likely to be cracked or cracked.

In the present invention, when used as a semiconductive belt, the polyimide resin layer needs to have a surface resistivity of 10 ⁹ to 10 ¹³ Ω / □, and preferably 10 ¹⁰ to 10 ¹² Ω / □. The surface resistivity can be adjusted by the type of conductive particles, the amount added, the particle size, and the like. If the surface resistivity exceeds 10 ¹³ Ω / □, frictional charging cannot be effectively prevented and the peeling offset prevention effect tends to be reduced. If it is less than 10 ⁹ Ω / □, the blending amount of the conductive particles increases, and the strength and durability of the belt tend to decrease. The volume resistivity of the polyimide resin layer is relatively small compared to the surface resistivity, and is usually 10 ⁶ to 10 ⁸ Ω · cm.

  In addition, as for the thickness of the polyimide resin layer in this invention, 1-100 micrometers is preferable. The polyimide resin layer may contain, in addition to the above essential components, a silicone-based organic compound, a coupling agent, a lubricant, an antioxidant, and other additives to the extent that the physical properties are not impaired. The resin may be copolymerized or blended with other polymer components to such an extent that the physical properties are not impaired.

  Moreover, in the seamless belt which has a multilayer structure, 1 type, or 2 or more types of layers can be laminated | stacked on the said polyimide resin layer according to the use of a belt. For example, when a seamless belt is used as a release belt, it is suitable to laminate a release layer made of fluororesin or silicone rubber, but it is not particularly limited. As other layers, an inorganic metal oxide thin layer for imparting wear resistance, or a fluororesin powder or ceramic powder-containing layer for adjusting slipperiness is provided depending on the purpose.

  Examples of the fluororesin that can be used for the release layer include PFA, PFA-modified PTFE, FEP, and PTFE. PFA is particularly preferable.

  As the silicone rubber that can be used for the release layer, general-purpose rubber can be used as long as the rubber hardness is about 20 to 50 degrees. For example, methyl silicone rubber, vinyl methyl silicone rubber, and fluoro silicone rubber can be used alone, or Two or more types can be used in combination.

  In order to adjust electric resistance, conductive particles such as carbon black may be added to the release layer. In addition, for the purpose of improving the adhesion between the polyimide resin layer and the release layer, a primer can also be used within the range of the resistance.

  The thickness of the release layer is usually 10 to 50 μm, preferably 10 to 40 μm, and more preferably 20 to 30 μm.

  The seamless belt of the present invention can be manufactured by the following steps.

(1) Step of forming a polyimide resin layer by centrifugal molding in a cylindrical mold When using a polyamic acid solution, if the solution viscosity is high, dilute with a suitable solvent and use it with a low viscosity. be able to. Any cylindrical mold can be used as long as it is conventionally used for the production of tubular bodies, and various materials such as metal, glass and ceramics are used from the viewpoint of heat resistance. Is exemplified. The method for applying the polyamic acid solution to the cylindrical mold is a method in which the cylindrical mold is rotated around an axis, the polyamic acid solution is supplied to the inner surface by a dispenser or the like, and a uniform film is applied by centrifugal force. The number of rotations of the mold at the time of centrifugal molding is not particularly limited, but can be appropriately set from the viewpoint of forming a uniform film and causing desired functional particle gradient dispersion. Usually, the rotation speed is about 500 to 3000 rpm.

  The heating temperature after applying the polyamic acid solution is not particularly limited and can be appropriately set. In particular, after heating at a low temperature of about 80 to 200 ° C. to remove the solvent, the temperature is raised to about 250 to 400 ° C. Thus, a multi-stage heating method for completing the imide conversion is preferable. Moreover, after forming a release layer etc. continuously after low temperature heating, high temperature heating may be performed and imide conversion may be performed. Although the heating time is appropriately set according to the heating temperature, both the low temperature heating and the subsequent high temperature heating are usually about 20 to 60 minutes. If such a multistage heating method is used, generation | occurrence | production of the microvoid in the tubular body resulting from ring-closing water and solvent evaporation which generate | occur | produce with imide conversion can be prevented. In addition, during heating, it is preferable to carry out while rotating a cylindrical metal mold | die for uniform heating and formation of a polyimide resin layer.

(2) Formation of primer layer When further laminating on the polyimide resin layer, a primer layer may be formed by applying a primer solution in order to improve adhesion between the layers.

(3) Formation of multiple layers by lamination When laminating a fluororesin layer, a method of coating the surface of a polyimide resin layer or a primer layer with a solution-like (including dispersion) fluororesin is used. As a method of coating the solution-like fluororesin solution, for example, a method of applying using a dispenser or a spray gun can be considered. During the coating and heating operations, it is preferable to carry out while rotating the cylindrical mold from the viewpoint of uniform heating and layer formation. As a procedure of application and heating, in order to prevent voids from being generated in the outer layer, after applying the fluororesin and removing the solvent in the fluororesin solution, the temperature is raised to the melting point of the fluororesin or higher to form the fluororesin layer. Can be formed. At this time, imide conversion of the polyimide resin layer may be performed simultaneously.

  When laminating the silicone rubber layer, a method of coating the surface of the polyimide resin layer or primer layer with a solution-like silicone rubber is used. As a method for coating the silicone rubber solution, for example, a coating method using a dispenser or a spray gun can be considered. During the coating and heating operations, it is preferable to carry out while rotating the cylindrical mold from the viewpoint of uniform heating and layer formation. In the case of silicone rubber solution application, a multilayer seamless belt having a layer made of silicone rubber is obtained by allowing to stand for 1 to 24 hours at a temperature of 20 to 150 ° C. to cure.

  The number of layers to be laminated can be appropriately set according to the purpose, but is usually about 1 to 3 layers.

  Although the thickness of the layer to laminate | stack can also be suitably set according to the objective, it can select from the range of 5-500 micrometers normally for each layer.

(4) Peeling of seamless belt from mold The seamless belt thus obtained is peeled from the cylindrical mold. Examples of the method for peeling the polyimide resin layer from the cylindrical mold include a method in which air is pressure-fed into a minute through-hole provided in advance on the peripheral wall surface of the cylindrical mold end. In addition, it is preferable to perform a release treatment with a silicone resin or the like in advance on the inner peripheral surface of the cylindrical mold, since the workability of removing the resin layer is improved.

(5) Inversion of the peeled seamless belt The inversion of the seamless belt can be easily performed by folding one end face of the seamless belt outward and moving the end face in the axial direction.

  As the seamless belt of the present invention, a belt having a relatively large diameter and a short length is suitable because of the easy reversal process.

[Example]
Examples and the like specifically showing the configuration and effects of the present invention will be described below.

[Example 1]
200 g of carbon black (MA100, manufactured by Mitsubishi Chemical Corporation, furnace black, average particle diameter of 22 nm based on primary particles) was added to 1800 g of N-methyl-2-pyrrolidone (NMP). After being dispersed by stirring at room temperature for 12 hours with a ball mill, it was filtered with a # 400 stainless steel mesh to obtain a carbon dispersion having a concentration of 10% by weight. 1327.46 g of this carbon dispersion was transferred to a 5000 mL four-necked flask, 1197.18 g of N-methyl-2-pyrrolidone, 129.77 g (1.2 mol) of p-phenylenediamine, 4,4′-diaminodiphenyl ether 60 0.06 g (0.3 mol) was charged and dissolved while stirring at room temperature. Next, 441.33 g (1.5 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was added, reacted at a temperature of 20 ° C. for 1 hour, and then heated at 75 ° C. for 50 hours. While stirring, a carbon black-containing polyamic acid solution having a solution viscosity of 10 Pa · s as measured by a B-type viscometer (solid content concentration 20 wt%, carbon black added amount is 23 parts by weight with respect to 100 parts by weight of resin solids) )

  This carbon black-containing polyamic acid solution was filtered using a # 800 stainless steel mesh to obtain a semiconductive polyamic acid solution.

  Next, the semiconductive polyamide solution was applied by a dispenser to the inner peripheral surface of a cylindrical mold having an inner diameter of 500 mm and a length of 300 mm, and the inner surface was roughened (Rz: 0.7 μm). It was rotated for 20 minutes to form a spread layer having a uniform thickness of 600 μm.

  Next, while rotating at 250 rpm, hot air of 130 ° C. was blown from the outside of the cylindrical mold for 30 minutes, then heated to 370 ° C. at a rate of 2 ° C./minute, and heated and cured at that temperature for 30 minutes. Cooling, peeling, and reversal were performed to obtain a desired seamless belt having a thickness of 75 μm. A cross-sectional view of the obtained seamless belt is shown in FIG. As shown in FIG. 1, the seamless belt of Example 1 was inverted so that carbon black was localized on the inner surface of the belt.

[Comparative Example 1]
A desired seamless belt was obtained in the same manner as in Example 1 except that the viscosity of the semiconductive polyamic acid solution was 100 Pa · s and the obtained belt was not reversed.

[Evaluation test]
The semiconductive seamless belts obtained in Example 1 and Comparative Example 1 were examined for the following characteristics.

(1) Surface resistivity Using Hiresta UP (manufactured by Mitsubishi Oil Chemical Co., Ltd.), the surface resistivity of a probe UR, an applied voltage of 250 V, and a value of 10 seconds was examined.

(2) Volume resistivity HIRESTA UP (manufactured by Mitsubishi Oil Chemical Co., Ltd.) was used to examine the volume resistivity of a probe UR, an applied voltage of 250 V, and a 10 second value.

(3) Surface roughness Rz
In accordance with JIS B 0601 (1982), samples were taken from any five points on the belt surface, and the circumferential direction was measured with a surface roughness meter (Surfcom 554A = manufactured by Tokyo Seimitsu Co., Ltd.) with a cutoff value of 0.32 mm. The measurement was performed at a length of 2.5 mm, a driving speed of 0.12 mm / sec, and a stylus load of 70 mg.

[Evaluation results]
The seamless belt obtained in Example 1 had a thickness variation of 8 μm, a volume resistivity of 4.0 × 10 ⁸ Ω · cm, and a surface resistivity of 2.3 × 10 ¹² Ω / □. The surface roughness Rz of the inner surface was 0.6 μm.

On the other hand, the thickness variation of the seamless belt obtained in Comparative Example 1 was 6 μm, the volume resistivity was 4.0 × 10 ⁹ Ω · cm, and the surface resistivity of the surface layer was 2.3 × 10 ¹¹ Ω / □. The surface roughness Rz of the inner surface was 0.1 μm.

  In the seamless belt of Comparative Example 1, the viscosity of the polyamic acid solution was increased in order to prevent carbon black from being localized due to centrifugal molding and lowering the surface resistivity of the surface layer, but the surface was higher than that of the seamless belt of Example 1. The resistivity was low, and conversely, the volume resistivity was high. Therefore, it has been shown that the method of the present invention in which the belt is inverted after centrifugal molding can provide a seamless belt that sufficiently exhibits the characteristics as an intermediate transfer belt. In addition, the seamless belt of Example 1 reflects the surface roughness of the mold used by the surface roughness of the inner surface, but the surface roughness of the inner surface of the seamless belt cannot be controlled by the method of Comparative Example 1, It can be seen that it is difficult to obtain a belt having a desired surface roughness.

[Example 2]
In a 5000 mL four-necked flask, 2414.16 g of N-methyl-2-pyrrolidone and 162.21 g (1.5 mol) of p-phenylenediamine were charged and dissolved while stirring at room temperature. Next, 441.33 g (1.5 mol) of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride was added, reacted at a temperature of 20 ° C. for 1 hour, and then heated at 75 ° C. for 50 hours. By stirring the mixture, a polyamic acid solution having a solution viscosity of 100 Pa · s by a B-type viscometer was obtained.

  This polyamic acid solution was filtered using a # 800 stainless steel mesh to obtain a polyamic acid solution.

  This polyamic acid solution was applied to the inner peripheral surface of a cylindrical mold having an inner diameter of 500 mm and a length of 300 mm and roughened (Rz: 1.5 μm) by a dispenser, and rotated at 1500 rpm for 20 minutes by a rotary molding machine. A spread layer having a uniform thickness of 600 μm was formed.

  Next, while rotating at 250 rpm, hot air of 130 ° C. was blown from the outside of the cylindrical cylinder for 30 minutes, then heated to 250 ° C. at a rate of 2 ° C./minute, heated at that temperature for 30 minutes, and then cooled. .

  Furthermore, after applying and drying a polyamic acid primer on the inner surface, a fluororesin dispersion (solid content concentration of 40% by weight) having a predetermined particle size of 0.2 to 0.3 μm is injected with a dispenser, It was slowly rotated and spread over the entire inner peripheral surface, and the number of rotations was increased to 500 rpm to form a uniform coating layer. Further, the mold temperature was raised to 110 ° C. while rotating at 20 rpm to dry and solidify. Thereafter, the mold was baked in a heating furnace at 400 ° C. for 60 minutes, cooled, and then peeled to obtain a seamless belt substrate having a total thickness of 88 μm having a fluororesin layer having a thickness of 12 μm on the inner surface.

  The obtained belt was cut into a width of 30 mm and turned over to obtain a desired seamless belt having a release layer composed of a fluororesin layer on the surface layer. A cross-sectional view thereof is shown in FIG. The surface roughness of the inverted belt was a front surface Rz = 0.2 μm and a back surface Rz = 1.2 μm. When this belt was used for heat sealing polyethylene, the driving performance and release properties were good and could be used without the need for replacement for one week.

Sectional drawing of the belt of Example 1 of this invention Sectional drawing of the belt of Example 2 of this invention

Explanation of symbols

1 Polyimide resin layer 2 Conductive particles 3 Fluorine resin layer

Claims (6)

A seamless belt having a polyimide resin layer formed by centrifugal molding at least in a cylindrical mold, wherein the mold non-contact surface side of the polyimide resin layer is an outer surface of the belt. The seamless belt according to claim 1, wherein the polyimide resin layer contains functional particles, and the functional particles are inclined and dispersed toward the inner surface of the belt in the thickness direction of the layer. The seamless belt according to claim 1 or 2, wherein a surface roughness Rz of the inner surface of the seamless belt is 0.2 µm to 3.0 µm. The seamless belt according to any one of claims 1 to 3, comprising a multilayer formed by further laminating the polyimide resin layer in the cylindrical mold. Including a step of forming a polyimide resin layer by centrifugal molding in a cylindrical mold, a step of obtaining a seamless belt having at least the formed polyimide resin layer, and a step of inverting the obtained seamless belt. The manufacturing method of the seamless belt in any one of Claims 1-4. The manufacturing method according to claim 5, wherein the step of obtaining the seamless belt is a step of further laminating the formed polyimide resin layer in the cylindrical mold to obtain a multilayer seamless belt.

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