JP2007021982A - Manufacturing method of seamless tube for seamless belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing, stably at a reduced cost, a seamless belt having less unevenness of the film thickness and excellent durability. <P>SOLUTION: The method is based on manufacturing a seamless tube for seamless belts by inflation molding, and uses an extruder for extruding a molten thermoplastic resin and an air ring having an annular die of a diameter D and an air blowing outlet. The ratio of the diameter Db of the seamless tube to the diameter D of the annular die, Db/D, is 1.1-2.7. The height H1 of the uppermost part of the first air blowing outlet is 30-100 mm. The ratio of the outside diameter R of the uppermost part of the first air blowing outlet to the diameter Dt of the tube-formed film at the position 30 mm higher than the height H2 of the uppermost part of the second air blowing outlet, R/Dt, is 0.8-1.2. The ratio of the diameter Dt of the tube-formed film at the position 30 mm higher than the height H2 of the uppermost part of the second air blowing outlet to the diameter Db of the seamless tube, Dt/Db, is ≥0.8. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a seamless belt used in an electrophotographic apparatus.

  The full-color electrophotographic apparatus includes a transfer conveyance belt (a belt used for transferring a toner image on an image carrier onto a recording paper such as paper) and an intermediate transfer belt (a toner image formed on a photoconductor on paper or the like). Seamless belt such as a belt used to obtain the image by transferring the toner image onto the intermediate transfer belt and then transferring the toner image on the intermediate transfer belt to the recording paper. Is used. And full-color electrophotographic apparatuses using these seamless belts are roughly classified into two types.

  One is a so-called tandem type full-color electronic device in which different color developers (toners) formed on a plurality of photoconductors as shown in FIGS. 1 and 2 are sequentially transferred by a transfer conveyance belt or an intermediate transfer belt. It is a photographic device.

  The other is one using a photoconductor and an intermediate transfer belt as shown in FIG. 3, and is a so-called four-pass type full-color electron that is transferred onto the transfer paper P after the intermediate transfer belt has rotated four times. It is a photographic device.

  In recent full-color electrophotographic apparatuses, improvement in printing speed is emphasized, and tandem-type full-color electrophotographic apparatuses that are advantageous for speeding up are increasing.

  In such a background, one of the functions required for the intermediate transfer belt and the transfer conveyance belt is that the belt moving speed is stable. If the moving speed is not stable, it is impossible to superimpose a plurality of color toner images on a desired position on the intermediate transfer belt or paper, and color misregistration occurs. Although there are several fluctuation factors of the belt moving speed, as a factor of the belt itself, uneven film thickness of the belt is a fluctuation factor of the belt moving speed.

  In the 4-pass type electrophotographic apparatus, the belt is rotated once to transfer the next color. Therefore, speed fluctuations caused by uneven film thickness of the belt, that is, color misregistration is canceled in principle, which is advantageous for color misregistration. However, in actuality, it is not completely canceled, and color misregistration due to uneven belt moving speed occurs slightly. On the other hand, in the case of the tandem type, since the transfer of the next color is performed while the belt does not rotate once, the film thickness unevenness of the belt is directly reflected in the color shift. For this reason, belts with even less film thickness unevenness are required for intermediate transfer belts and transfer conveyance belts used in tandem types.

  In recent years, the price has been remarkably reduced regardless of whether it is a tandem type or a 4-pass type, and further cost reduction is required for the intermediate transfer belt and the transfer conveyance belt.

  Under such circumstances, intermediate transfer belts and transfer conveyance belts currently used in the market can be roughly classified into three from the viewpoints of materials and manufacturing methods.

  The first is a so-called thermosetting type resin belt in which a conductive agent is added to a resin (precursor) before thermosetting, and then solidified by a curing reaction by heating. A typical example is a polyimide resin. It is a belt (refer patent document 1). This type of belt is often manufactured by a so-called centrifugal molding method in which a coating material that forms a belt is applied in a mold and the coating material is spread uniformly in the mold by centrifugal force. For this reason, although the obtained belt has an advantage of excellent film thickness uniformity, it takes a long time for thermosetting and solvent evaporation, and is not suitable for low-cost production.

  The second is a belt made by adding a conductive agent to rubber, vulcanizing and polishing. With this type of belt, a belt having excellent durability can be obtained by inserting a core such as fiber. However, it takes a long time for vulcanization and polishing, which is disadvantageous for low-cost production. Further, since the belt is easily elastically deformed when the belt is driven and a minute speed fluctuation is likely to occur in the belt moving speed, color misregistration is likely to occur.

  The third is a belt cut into a predetermined length after extruding a resin composition obtained by adding a conductive agent to a thermoplastic resin into a tube shape. Since this belt enables low-cost production by continuous extrusion, it is most advantageous for cost reduction and is currently the most mainstream seamless belt manufacturing method. For example, a method is disclosed in which a tube extruded from an annular die is brought into contact with a temperature-controlled mandrel and a temperature-controlled gas is sprayed (see Patent Document 2).

  However, since the tube extruded by this method is manufactured in contact with the mandrel, a long-period film thickness unevenness (uneven thickness) in the belt circumferential direction is large due to a slight variation in the contact state between the tube and the mandrel. It was a thing. In addition, individual differences in film thickness unevenness are severe, and it has been impossible to stably obtain a sample with favorable film thickness unevenness. Also, film thickness unevenness was observed in a short period in the belt circumferential direction due to flow unevenness (extrusion lines) of the thermoplastic resin in the circumferential direction of the annular die. According to the study by the present applicants and the like, when the belt obtained as described above is mounted on an image forming apparatus and used, color misregistration and durability cracks occur.

On the other hand, the present applicants use a thermoplastic resin to be melt-extruded having a certain thermal characteristic in inflation molding, which is a type of extrusion molding, and the extruded cylindrical melt is converted into a diameter of an annular die. It has been found that a seamless belt with relatively small film thickness unevenness can be obtained by expanding the film to 100 to 400% and gradually cooling at room temperature (see Patent Document 3).
JP 2001-064389 A Japanese Patent No. 2886350 JP 2001-252988 A

  However, since the film is expanded while being slowly cooled, even a slight air flow generated by the movement of the operator may affect the film thickness unevenness. The film has unevenness in the film thickness in a short period in the belt circumferential direction due to the extrusion stripe, and in some cases, cracks may occur due to durability.

  As described above, a technique for producing a seamless belt that is low in cost and satisfies color shift and durability when used in an image forming apparatus has not yet been established.

  Accordingly, the present inventors propose a novel seamless belt manufacturing method that solves the above-described problems.

  Accordingly, an object of the present invention is to provide a manufacturing method capable of stably and inexpensively manufacturing a seamless tube for a seamless belt having excellent durability with very little film thickness unevenness.

  To achieve the above object, the present invention provides a seamless tube for a seamless belt manufactured by inflation molding, an extruder for melting and extruding a thermoplastic resin, an annular die having a diameter D, a plurality of Using an air ring having an air outlet, the relationship between the diameter D of the annular die and the diameter Db of the seamless tube is 1.1 ≦ Db / D ≦ 2.7, and the height H1 at the top of the first air outlet [Mm] is 30 ≦ H1 ≦ 100, the outer diameter R of the uppermost portion of the first air outlet, and the diameter of the tubular film at a position 30 mm above the height H2 of the uppermost portion of the second air outlet. Dt is 0.8 ≦ R / Dt ≦ 1.2, the diameter Dt of the tubular film and the seam at a position 30 mm above the height H2 at the top of the second air outlet Relationship diameter Db of the scan tube, characterized in that a 0.8 ≦ Dt / Db.

  According to the present invention, a seamless tube for a seamless belt having very little film thickness unevenness and excellent durability can be manufactured stably at low cost.

  First, the background to which the present inventors have reached the present invention will be described.

  Prior to the present invention, the applicants of the present application thought that it was only necessary to improve the film thickness accuracy in the belt circumferential direction in order to reduce the color misregistration caused by the film thickness unevenness of the belt. Further, it has been considered that the durability of the belt is improved by using a material having high mechanical properties as a material used for the belt.

  However, as a result of trial manufacture and evaluation of various belts, there was not much correlation between the color misregistration and simply what the film thickness unevenness of the belt is ±. Further, there was not much correlation between the belt elastic modulus and the belt durability.

  As a result of a detailed study on the above-mentioned points, long-period film thickness unevenness (uneven thickness) in the belt circumferential direction has a significant effect on color misregistration, and short-period film thickness unevenness in the belt circumferential direction has a significant effect on belt durability. I found that it had a big influence.

  One of the major causes of long-period film thickness unevenness (unevenness) in the belt circumferential direction that affects color misregistration in a tandem type image forming apparatus is a seamless belt (intermediate transfer) that transports transfer materials such as images or paper As described above, it is the fluctuation of the surface speed of the belt or transfer / conveying belt. For example, in the case of a tandem type image forming apparatus having four image forming portions of four colors (yellow, magenta, cyan, black), the first is used when the belt has long-period thickness unevenness (unevenness). The belt surface moving speed in the image forming unit and the belt surface moving speed in the fourth image forming unit are greatly different, and as a result, the first color component and the fourth color component are largely color-shifted.

  In addition, the reason why uneven film thickness in the circumferential direction of the belt affects the belt durability is that the belt generally has a meandering prevention member installed on the inner peripheral surface of the belt and stretched around the roller. However, due to factors such as a subtle difference in the circumferential length of the belt and a misalignment of the roller that stretches the belt, the belt generates a force (shift force) that moves toward one side in the belt axis direction. Due to the presence of the meandering prevention member, this axial deviation force is converted from an axial deviation force into a force that causes the meandering prevention member to ride up from a groove fitted to the meandering prevention member. Here, when there is no film thickness unevenness of a short period, this force can be absorbed by dispersing the force uniformly in the belt circumferential direction. However, in the case where the film thickness unevenness has a short cycle, it is considered that cracks are generated because tension is concentrated on a portion having a smaller film thickness than the surrounding area.

  From the above, as a result of intensive studies on a manufacturing method that can obtain a low-cost seamless belt without long-cycle and short-cycle film thickness unevenness in the belt circumferential direction, as a result of inflation molding, When manufactured under the condition that the relationship between the dimensions and the shape of the tube-shaped film is within a certain range, there is no long-cycle and short-cycle film thickness unevenness in the circumferential direction of the tube-shaped film, and it can be manufactured stably for a long time. The headline has led to the present invention.

That is, it is a method for producing a seamless tube for a seamless belt produced by inflation molding, and uses an extruder for melting and extruding a thermoplastic resin, an annular die having a diameter D, and an air ring having a plurality of air outlets. ,
The relationship between the diameter D of the annular die and the diameter Db of the seamless tube is 1.1 ≦ Db / D ≦ 2.7,
The height H1 [mm] at the top of the first air outlet is 30 ≦ H1 ≦ 100,
The relationship between the outer diameter R of the uppermost portion of the first air outlet and the diameter Dt of the tubular film at a position 30 mm above the height H2 of the uppermost portion of the second air outlet is 0.8 ≦ R / Dt ≦ 1.2,
The relationship between the diameter Dt of the tubular film and the diameter Db of the seamless tube at a position of 30 mm above the height H2 of the uppermost portion of the second air outlet is 0.8 ≦ Dt / Db,
The seamless belt manufacturing method for seamless belts makes it possible to reduce long-cycle and short-cycle film thickness unevenness in the belt circumferential direction, reducing color misregistration and high durability when used in image forming measures. Can be satisfied.

  Here, the present invention will be described in detail with reference to FIGS.

  FIG. 4 is a schematic view of an inflation molding machine.

  In FIG. 4, 100 is an extruder, and a thermoplastic resin composition in which a resistance adjusting agent or the like is dispersed in advance is put into a hopper 110, and is heated by a heater installed in the extruder and shear heat generated by an extrusion screw. The resin composition is melted and extruded, and the tubular film 160 is discharged from the annular die 140. The discharged tubular film 160 is controlled in diameter by air from an air supply / exhaust passage for adjusting the tubular film diameter provided in the annular die 140, and is supplied to a blower such as a blower (not shown) via the air supply port 210. After being cooled by the air from the connected air ring 200 and gradually folded by the stabilizing plate 170, it is completely folded by the pinch roll 180 and taken out. The film folded with a pinch roll is cut into an arbitrary length by a cutter 190, and a seamless tube 220 is obtained.

  FIG. 5 is an enlarged view of the vicinity of the air ring 200, and includes a first air outlet 201 and a second air outlet 202. The thermoplastic resin is heated and melted by an extruder (not shown), extruded, and discharged from the annular die 140 into a tube shape. The thermoplastic resin discharged in a tube shape is taken up by a take-off device (not shown) while being expanded by the venturi effect due to the air flow blown out from the air ring and the pressure of the gas introduced into the tube, and is taken into a tube-like film. 160.

  In the present invention, Db refers to the tube-shaped film diameter after cooling and solidification, and the seamless tube diameter Db can also be obtained by calculation from the width (folded diameter) of the film folded by a pinch roll (not shown). Further, in the present invention, Dt refers to the diameter of the tubular film at a position further 30 mm above the height H2 from the die surface at the uppermost part of the second air outlet.

  Db / D, which is the relationship between the diameter Db of the seamless tube and the diameter D of the annular die, that is, the blow ratio needs to be 1.1 or more and 2.7 or less. If the blow ratio is less than 1.1, long-period film thickness unevenness (uneven thickness) in the belt circumferential direction and short-cycle film thickness unevenness due to extrusion stripes deteriorate, and if it exceeds 2.7, molding stability decreases. A preferable range of Db / D (blow ratio) is 1.3 or more and 2.0 or less.

  In addition, the relationship between the diameter Dt of the tubular film at the specified position and the outer diameter R of the uppermost portion of the first air blowing port needs to be 0.8 ≦ R / Dt ≦ 1.2. The relationship between the diameter Dt of the tube-like film and the diameter Db of the seamless tube needs to be 0.8 ≦ Dt / Db, and preferably 0.9 ≦ Dt / Db. This is because the tube-like film discharged from the annular die is sucked up by the venturi effect by the air flow blown out from the air ring, and rapidly expanded to the outer diameter of the first air outlet, and thereafter It means to suppress the dimensional change of the tubular film.

  Only when such a tube shape is controlled, it is possible to reduce both long-cycle and short-cycle film thickness unevenness in the belt circumferential direction. The reason is that the tube-like film can be deformed in a high temperature state, that is, in a state where the viscosity is relatively low, by rapidly expanding from a portion close to the die, and a portion discharged thicker than other portions is stretched. It is easy to be thinned. At the same time, since the tubular film is rapidly expanded to the vicinity of the first air outlet of the air ring, the portion discharged thinner than the other portions is rapidly cooled by the air from the air ring. It is hard to be thin. For this reason, it is considered that both short-period film thickness irregularities such as extrusion stripes and long-period film thickness irregularities due to subtle alignment misalignment and temperature irregularities of the annular die can be efficiently removed.

  Furthermore, by setting such conditions, there is almost no change in the film thickness unevenness profile in the circumferential direction due to the molding time, and adjustment for precise film thickness unevenness removal becomes possible.

  The reason is that the tube-like film is stabilized by the air blown from the air ring because the tube-like film is sucked up to the vicinity of the first air outlet by the venturi effect by the air flow blown from the air ring. One reason is considered to be cooled.

  On the contrary, when the sticking of the tubular film to the first air outlet is weak, the tubular film causes a subtle precession. As a result of causing precession, uniform cooling is not performed in the circumferential direction of the tubular film, uneven thickness occurs, and the thickness of the uneven thickness changes with time. The cycle of precession varies depending on the strength of the air blown out from the air ring, but it occurs at a relatively short cycle of several Hz to several tens of Hz, and the seamless tube is continuously set to an appropriate length (for example, 300 mm). There may be a case where the profile of the film thickness unevenness is different between a certain one of the cut tubular films and the next one.

Further, by making the outer diameter dimension of the first air outlet and the diameter of the tube-like film at the specified position substantially equal, the air blown from the second air outlet is along the surface of the tube-like film. Thus, it is considered that the influence of disturbance on the cooling of the tubular film is less likely to be affected by the disturbance as a second reason for suppressing the change in the film thickness unevenness profile in the circumferential direction due to the molding time. For these reasons, the outer diameter R2 of the second air outlet is preferably larger than the diameter Db of the seamless tube. As a method of controlling to such a tube shape,
1) Adjust the diameter of the annular die and the die gap (interval of the portion where the thermoplastic resin at the tip of the die is discharged) 2) Adjust the set temperature of the molding device and adjust the viscosity of the thermoplastic resin to be discharged 3) Adjust the amount and temperature of air blown from the air ring. 4) Adjust the ratio of air blown from the first and second air outlets, the wind speed, etc. 5) Adjust the shape and dimensions of the air outlet. The take-up speed can be adjusted, and can be combined with each other, but is not limited thereto.

  Further, the height H1 from the die surface at the uppermost part of the first air outlet needs to be 30 mm ≦ H1 ≦ 100 mm. When H1 is out of this range, it becomes very difficult to control R / Db within the above range.

  The thermoplastic resin that can be used in the present invention is not particularly limited. For example, olefin resins such as polyethylene and polypropylene, polystyrene resins, acrylic resins, aromatic polyester resins such as polyethylene terephthalate, polycarbonate, and polyarylate, Alicyclic polyester resins such as cyclohexylenedimethylene terephthalate, sulfur-containing resins such as polysulfone, polyethersulfone and polyphenylene sulfide, fluorine-containing resins such as polyvinylidene fluoride and polyethylene-tetrafluoroethylene copolymer (ETFE), Polyurethane resin, silicone resin, ketone resin, polyvinylidene chloride, thermoplastic polyimide resin, polyamide resin, modified polyphenylene oxide resin, and various modified resins and copolymers Although it is Rukoto not limited to the above materials. Moreover, these thermoplastic resins may be used independently and may be used in mixture of multiple types. Among these thermoplastic resins, it is preferable to use a crystalline resin as the main thermoplastic resin component because of its excellent bending resistance. Polyamide 12 resin, polyphenylene sulfide resin, polyvinylidene fluoride, and ETFE are melted in the crystalline resin. This is particularly preferable because the tension is high and the tube shape of the present invention can be easily controlled.

  In addition, the seamless belt of the present invention may contain a conductivity-imparting agent in order to control electrical resistance. Examples of the conductivity-imparting agent include a charging unit containing a polyether unit such as polyetherester or polyetheresteramide. Prevention resin, tetraalkylammonium salt, trialkylbenzyl, ammonium salt, alkyl sulfonate, alkylbenzene sulfonate, alkyl sulfate, glycerin fatty acid ester, sorbitan fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty alcohol ester, alkyl Ionic conductivity imparting agents such as betaine and lithium perchlorate, carbon black, graphite, aluminum-doped zinc oxide, tin oxide-coated titanium oxide, tin oxide, tin oxide-coated barium sulfate, potassium titanate, Al Examples thereof include conductive fillers such as a nium metal powder and a nickel metal powder, and since the electrical resistance can be controlled in a wide range, it is preferable to add the conductive filler as a conductivity imparting agent for the seamless belt. The conductivity-imparting agent that can be used in the above is not limited to the above substances.

  The seamless belt of the present invention may contain various additives. Examples of various additives include organic pigments, inorganic pigments, pH adjusters, crosslinking agents, mold release agents, coupling agents, lubricants, antioxidants, hydrolysis inhibitors, molding aids, and the like. Two or more of these can be combined.

  As the air ring of the present invention, a known air ring can be used, but an air ring having a plurality of heaters in the circumferential direction of the cooling air flow path and capable of adjusting the temperature by dividing the cooling air is used. However, it is preferable because the uneven thickness of the seamless tube can be effectively removed.

  That is, a gas having a high temperature is sprayed on a portion where the tube is thick, and a gas having a low temperature is sprayed on a thin portion. If it does in this way, since a thick part becomes high temperature, time until it solidifies becomes long. Since the tube before solidification is stretched by pulling and becomes thin, the slower the solidification is, the thinner the tube is stretched. On the contrary, the portion sprayed with the low-temperature gas is solidified quickly, and is not stretched so much. As a result, it is possible to obtain a function in which the thick part is thinner and the thin part is not too thin, and the film thickness unevenness can be removed more precisely. Such an effect is an effect that is noticeable only when the tubular film shape is within the range of the present invention. That is, when the tubular film shape deviates from the scope of the present invention, as described above, the change in the profile of the film thickness unevenness in the circumferential direction occurs in a short time, so partial temperature adjustment of the cooling air is performed. However, it is not always possible to obtain a tubular film with small film thickness unevenness.

  In the present invention, when using an air ring that has a plurality of heaters in the circumferential direction of the cooling air flow path and can control the temperature by dividing the cooling air, the phase in which the temperature of the sprayed gas becomes the highest temperature, How much temperature difference is given to the gas at the low temperature phase is proportional to the degree of film thickness unevenness, but is preferably in the range of about 5 to 100 ° C. When the temperature difference is smaller than 5 ° C., there is almost no effect of removing the film thickness unevenness. If the film thickness unevenness is so large that the temperature difference must be greater than 100 ° C., it becomes difficult to pull the tube straight upward.

  In order to change the temperature of the cooling air in the circumferential direction, the power supplied to the plurality of heaters arranged in the circumferential direction of the cooling air flow path may be individually controlled.

  For example, a method of cycle controlling the heater output can be used. The cycle control is a method in which energization control is performed for all heaters with a predetermined time as one cycle. For example, when 5 seconds is set as one cycle, the control is performed by energizing 0.05 seconds per 1% output. When this cycle control is performed, it is preferable to set the cycle period to 30 seconds or less.

  If it is longer than 30 seconds, the temperature of the wind changes in conjunction with the ON / OFF of the heater, so the film thickness also changes. Although there is no lower limit of the period, it is practically about 0.1 second. Of course, the control method of the input power to the heater is not limited to this, and other control methods such as a phase control method may be used.

  It is preferable to provide a heat insulating member (insulator) between adjacent heaters. If there is no heat insulating member, the heat of the adjacent heater interferes and the effect of individual control is reduced. In addition, it seems that it is preferable to provide a partition in the circumferential direction inside the air ring and arrange one heater in each partitioned room, avoiding interference between adjacent heaters, but the gas flow is divided by the partition. Since the uniformity of the flow rate or flow velocity in the circumferential direction is likely to be impaired, it is better not to divide the inside of the air ring in the circumferential direction.

  The distance from the heater to the outlet is preferably about 100 to 600 mm. If it is closer than 100 mm, the non-uniformity of the wind flow due to the heater shape is not alleviated, which causes film thickness unevenness. When the distance is more than 600 mm, the wind flowing through the adjacent heaters is mixed and the temperature difference between the winds is eliminated, so that the effect of removing the uneven thickness is reduced.

  That is, it is preferable to use a heat sink attached to each heater in FIG. 8 having a small heat capacity because the gas temperature control response is improved. The range of the preferable heat capacity varies depending on the output (W) of the heater. For example, when the heater output is 200 (W), the heat capacity of the heat sink is preferably 2 to 100 (J / K). More preferably, it is 3-30 (J / K). The smaller the heat capacity, the better the control response, which is preferable. However, when a heat sink having a heat capacity smaller than 2 (J / K) is to be manufactured, the heat sink becomes very thin and it is difficult to increase the mechanical strength. The upper limit of the heat capacity range of the heat sink is directly proportional to the heater output. That is, when the heater output is 100 (W), the preferable range of the heat capacity of the heat sink is 2 to 50 (J / K). 3-15 (J / K) is more preferable.

  The larger the number of heaters, the more preferable it is because the uneven thickness in the circumferential direction of the seamless tube can be finely adjusted. However, if the number of heaters is increased too much, adjacent heaters are likely to interfere with each other. The range of is preferable.

  Here, a procedure for reducing the uneven thickness of the seamless tube by using an air ring that has a plurality of heaters in the circumferential direction of the cooling air flow path and can control the temperature by dividing the cooling air will be described.

  First, inflation molding is performed with all heaters arranged in the circumferential direction of the air ring being in the operation OFF state. And it adjusts so that the positional relationship of a tubular film and an air ring may become the range of this invention as mentioned above. The heater operation OFF state corresponds to the case where molding is performed using a normal air ring. The tube obtained at this time is referred to as tube A.

  The film thickness of the tube A at a position equally divided into the same number as the heater installed in the air ring is measured so that the phase of the plurality of heaters corresponds to the measurement phase of the film thickness of the tube A. In order to reduce the influence of the measurement error, the film thickness is measured at three locations in the axial direction using a measuring apparatus as shown in FIG. 6 and three measured values (values corresponding to gauge 1 to gauge 3). Is the film thickness in the measurement phase.

  In this film thickness measurement data, (film thickness at each measurement phase) − (thickness at the thinnest phase) is obtained, and the value is multiplied by a proportional coefficient (gain) to determine the output of each heater. Control of each heater is started. The tube obtained after a sufficient time has elapsed from the start of control is referred to as tube B.

  When the film thickness measurement result of tube B and the film thickness measurement result of tube A are compared, the part where the film thickness is thick in tube A is thick even in tube B, and the part where the film thickness is thin in tube A is thin even in tube B Since the gain is insufficient, the gain is increased and each heater is controlled again. In the opposite case, the gain is decreased.

  By determining each heater output in the above procedure, the film thickness unevenness can be corrected satisfactorily.

  Here, since the normal gain is determined by the inflation molding condition and the material of the seamless tube, when manufacturing the seamless tube with the same molding condition and material, the film thickness unevenness can be corrected with substantially the same gain.

  In the present invention, it is preferable to install a gear pump between an extruder for melting and extruding a thermoplastic resin and an annular die because a stable discharge amount can be obtained. The gear used for the metering section of the gear pump is preferably as fine as possible because the pulsation of the metering is fine. However, if the gear is too fine, the durability of the gear is reduced. Is preferred. For example, if the take-up speed of the seamless tube is 9 m / min, the rotation speed of the gear pump is 30 rotations / min, and the number of gear teeth in the measuring section is 60, the number of gear teeth per 100 mm of the seamless tube is 20.

  In addition, the seamless tube take-off speed in the present invention is preferably 5 m / min or more and 20 m / min or less because the molding stability of the seamless tube is very high.

  Since the method of measuring the diameter of the seamless tube at the specified position needs to be measured without contact, the air outlet of the air ring and the vicinity of the tubular film are photographed, and the air outlet is From the relationship between the dimensions of the tube-like film and the dimensions of the tube-like film, a method of measuring the dimension of the tube-like film and a method of using a displacement meter using a laser can be mentioned. When photographing the air outlet and the vicinity of the tubular film and measuring the dimensions of the tubular film, at least 10 images are photographed and measured under the same conditions, and the average value is used.

The diameter Db of the seamless tube of the present invention and the diameter Dt of the tubular film at the specified position were measured as follows. However, when the following measurement is difficult due to restrictions such as the air ring shape, the above Measurement by photographing may be used.
<Measurement of tube-shaped film diameter Dt>
<Measuring machine>
Laser displacement meter controller: VG-300 (manufactured by Keyence Corporation)
Laser displacement sensor head: VG-035 (manufactured by Keyence Corporation)
Two pairs of the above laser displacement meter sensor heads are set so that the center of the sensor head is located at a height of 30 mm from the first air outlet of the air ring, and two laser displacement meter controllers VG-300 are set. Connect to each.

  In detail, it demonstrates using FIG. 7 which is the schematic of the tubular film vicinity in the position 30 mm higher from the uppermost part of the 2nd air blowing outlet.

  Two pairs of sensor heads VG-035 are set at a known distance Wk so that the light projecting surface and the light receiving surface face the tube-shaped film, and the widths W1 and W2 of the portions shielded by the tube-shaped film are respectively To the controller VG-300. At this time, as the values of W1 and W2, an average value of 10 seconds sampled from 64 times averaged by the controller VG-300 is used.

That is, the diameter Dt of the tubular film at the specified position is the sum of the distance Wk between the sensor heads and the distances W1 and W2 of the portion shielded from light by the tubular film,
Dt = Wk + W1 + W2
And
<Measurement of seamless tube diameter Db>
Measure the width (folded diameter) of the tubular film folded with a pinch roll using the same equipment used for measuring the diameter Dt of the tubular film, and calculate the seamless tube diameter from the measured folded diameter. did. That is, the diameter of the seamless tube was calculated by doubling the measured folding diameter to calculate the circumference of the seamless tube, and dividing the calculated circumference by the circumference.

  As a seamless tube manufactured by this invention, 70-150 micrometers of average thickness is preferable. When the thickness is less than 70 μm, the strength when used as a belt is insufficient, and it tends to break during durability. If it is thicker than 150 μm, the rigidity of the belt becomes too high, and smooth driving becomes difficult. A preferable thickness range is 80 to 120 μm.

The film thickness is measured as follows.
<Measurement of film thickness>
<Measuring machine>
As shown in FIG. 6, a measuring machine is used in which three thickness gauges are installed at positions separated from each other by 100 mm, and the belt thickness can be measured at three locations simultaneously. In order to accurately measure the film thickness, the gauge preferably has a repeated measurement accuracy of 1 μm or less. In the present invention, linear gauge LBG2-0105L (manufactured by Mitutoyo) was used. The shape of the tip of the probe was a shape having a part of a spherical surface (SΦ5) having a diameter of 5 mm. The measuring machine of FIG. 13 has a mechanism capable of intermittently feeding a stretched belt by an arbitrary distance by intermittently rotating a roller for stretching the belt by an arbitrary angle. When this measuring machine is used, the thickness of three locations in the axial direction is measured simultaneously in an arbitrary phase in the circumferential direction of the seamless tube. The arithmetic average value of these three measured values is seamlessly measured in the measurement phase. It was set as the film thickness of the tube.

  In the present invention, long-period film thickness unevenness and short-cycle film thickness unevenness are defined as follows.

  That is, in the present invention, Z represented by the following equation is used as a parameter indicating the long-period film thickness unevenness.

Ｚは以下のようにして求める。

Z is obtained as follows.

  Measure 40 points at a measurement pitch of 1/40 of the seamless tube with the film thickness measuring instrument described above. The thickness t (μm) at each measurement position is expressed as tn (μm) (subscript of tn: n is 1 to 40). Here, since measurement is performed using three gauges at each measurement position, the thickness t is an arithmetic average value of each gauge. If the phase of the film thickness measurement start position (measurement position of t1) is 0 °, the measurement phase is 0 °, 9 ° (measurement position of t2), 18 ° (measurement position of t3), ... 351 ° (measurement of t40) The position of the seamless tube is measured every 9 °.

  Using the t1 to t40 obtained in this way and obtaining Z according to the above-described equation, Z corresponds to the center of gravity of the surface surrounded by the pie chart when t1 to t40 are displayed in a pie chart (FIG. 12). reference). That is, the smaller the long-period film thickness unevenness (uneven thickness), the smaller the value of Z, and the smaller the color shift when used as an electrophotographic seamless belt. In order to obtain a good color shift as an electrophotographic seamless belt, specifically, the value of Z is preferably 2.0 or less, and more preferably 1.0 or less.

  On the other hand, as a parameter indicating the short-period film thickness unevenness, S represented by the following equation was used.

S = (tmax−tmin) × 100 / tave
S is obtained as follows.

  With the above-described film thickness measuring device, a length corresponding to 10% of the circumference of the seamless tube is measured at a measurement pitch of 1 mm. In the measured film thickness data, the thickest value is tmax, the thinnest value is tmin, the average value of all measurement data is tave, and S is obtained according to the above equation. That is, the smaller the short-period film thickness unevenness, the smaller the value of S, and the durability when used as a seamless belt for electrophotography is improved. In order to obtain an electrophotographic seamless belt having good durability, specifically, the value of S is preferably 10 or less, more preferably 5 or less.

The volume resistivity of the seamless tube produced by the present invention is 10 ⁸ (Ω · cm) to 1013 (Ω · cm).

More specifically, when used as a transfer conveyance belt, the volume resistivity is preferably 10 ⁹ to 10 ¹³ (Ω · cm). 10 ⁹ When using the (Ω · cm) than low resistance belt as a transfer conveying belt, especially in high-temperature and high-humidity environment, reliably attracted to the transfer conveyance belt recording paper P, conveys the recording sheet P at a constant speed The ability is inferior and color misregistration tends to deteriorate. If the resistance is higher than 10 ¹³ (Ω · cm), it becomes difficult for the transfer current to flow, and a correspondingly high transfer voltage is required. Therefore, abnormal discharge during transfer is likely to occur, and image defects are likely to occur.

When the belt of the present invention is used as an intermediate transfer belt, the volume resistivity is preferably 10 ⁸ to 10 ¹² (Ω · cm). When a belt having a resistance lower than 10 ⁹ (Ω · cm) is used as the intermediate transfer belt, a punch-through image (a portion having a low density occurs in a part of the image) is likely to occur. In the case of an intermediate transfer belt, since the toner is directly transferred onto the belt without transferring the paper when transferring toner from the photosensitive member, the belt resistance is easily affected, and the belt resistance is low. This is thought to be due to the fact that the typical voltage increases and abnormal discharge occurs, making it difficult to completely transfer from the photoreceptor. When 10 ¹³ (Ω · cm) than the resistance is high, the transfer current becomes difficult to flow, because it requires correspondingly high transfer voltage, abnormal discharge is liable to occur at the time of transfer, the image defect is liable out.

The volume resistivity is measured as follows.
<Measurement of volume resistivity>
<Measurement device>
Resistance meter: Super high resistance meter R8340A (manufactured by Advantest)
Sample box: Sample box TR42 (manufactured by Advantest) for measuring ultrahigh resistance meter
(The main electrode is a metal having a diameter of 22 mm and a thickness of 10 mm, and the guard ring electrode is a metal having an inner diameter of 41 mm and an outer diameter of 49 mm and a thickness of 10 mm.)
<Sample>
A round test piece having a diameter of 56 mm is cut out from the seamless tube. On one side of the cut specimen, a vapor deposition film electrode is provided by performing Pt—Pd vapor deposition on the entire surface, and on the other surface, a Pt—Pd vapor deposition film is used to form a main electrode film having a diameter of 25 mm and an inner diameter of 38 mm. A guard ring electrode film having an outer diameter of 50 mm is provided concentrically. The Pt—Pd vapor deposition film is obtained by performing a vapor deposition operation for 2 minutes at a current value of 15 mA using mild sputtering E1030 (manufactured by Hitachi, Ltd.). The sample after the vapor deposition operation is used as a measurement sample. At the time of measurement, a φ22 mm main electrode is placed on the membrane so as not to protrude from the φ25 mm main electrode membrane. Further, a guard ring electrode having an inner diameter of 41 mm is placed on the film so as not to protrude from the guard ring electrode film having an inner diameter of 38 mm.
<Measurement conditions>
Measurement atmosphere: 23 ° C./50% RH
(Measurement samples are left in the measurement atmosphere for 24 hours in advance)
Measurement mode: Program mode 5
(Charge and major 30 seconds, discharge 10 seconds)
Applied voltage: 100 (V)
Other conditions and volume resistivity calculation are based on ASTM-D257-78.

  Further, when the seamless tube manufactured by the manufacturing method of the present invention is used as a seamless belt of an electrophotographic apparatus, the crease of the seamless tube can be removed by the method as shown in FIGS. It is not limited to this method. An example of the seamless tube crease removal method will be described below with reference to FIGS.

  FIG. 10 is a view for explaining the cylindrical inner mold 301 used for removing the crease in the seamless tube.

In FIG.
(1) A heat-shrinkable PFA (tetrafluoroethylene-perfluoroalkyl) having a thickness of about 0.5 mm is formed on the outer peripheral surface of an aluminum cylinder having an outer peripheral length slightly shorter (about 1%) than the inner peripheral length of the seamless tube. (Vinyl ether copolymer) Cover the tube.
(2) After the PFA tube is heated and shrunk at 220 ° C., the end portion is wound inside the aluminum cylinder and fixed with a PFA fixing member.

  Inside the aluminum cylindrical body, a gas supply / exhaust port having a check valve at the tip is provided.

FIG. 11 illustrates a crease removal method for a seamless tube using the cylindrical inner mold 301 of FIG. Each process of (1)-(4) of FIG. 11 is demonstrated in detail.
(1) The seamless tube 220 is fitted to the outer peripheral surface of the cylindrical inner mold 301.
(2) A gas having a low pressure (for example, 0.2 MPa) that allows the folds of the seamless tube to extend is introduced into the gas supply / exhaust port of the cylindrical inner mold 301 to which the seamless tube 220 is fitted, and the surface of the cylindrical inner mold 301 is seamless. The tube 220 is held.
(3) A cylindrical outer mold having an inner circumferential length slightly larger than the outer circumferential length of the seamless tube on the outer circumference of the cylindrical inner mold 301 with the seamless tube 220 fitted on the outer circumference, and a transfer surface on the inner circumferential surface. The mold 302 is fitted.
(4) With the cylindrical outer mold 302 fitted, the pressure (e.g., such that the outer surface of the seamless tube 220 and the inner peripheral surface of the cylindrical outer mold 302 are in close contact with the gas supply / exhaust port of the cylindrical inner mold 301 0.5 MPa) gas is introduced. In this state, after heating and cooling to a temperature equal to or higher than the heat distortion temperature of the seamless tube, the seamless belt from which the folds of the seamless tube 220 are removed can be obtained by extracting the gas from the gas supply / exhaust port.

  The seamless belt from which the creases have been removed as described above is used with a meander-preventing member made of rubber, elastomer or foam thereof. Moreover, you may provide the edge part reinforcement tape which consists of polyethylene terephthalate resin etc. in the inner peripheral surface edge part or outer peripheral surface edge part of a seamless belt.

Hereinafter, the present invention will be described in detail with reference to examples.
[Example 1]
Using a biaxial extruder, thermoplastic resin pellets having the following composition were prepared.

<Combination>
Polyvinylidene fluoride resin 87.8 wt%
Conductive carbon black 6.2wt%
Polyether ester amide resin 1.0wt%
Zinc oxide 5.0wt%
Next, 100 pellets having a thickness of about 100 μm, a length of 300 mm, and a folding diameter of 240 mm were produced by subjecting the pellets to inflation molding at 220 ° C. using the inflation molding apparatus shown in FIG.

  Here, as the air ring, one having two air outlets as shown in FIGS. 5 and 8 and the inside of which is not partitioned in the circumferential direction was used.

  In addition, as shown in FIG. 8, 40 cartridge heaters of 200 (W) are arranged inside the air ring on a pitch circle of Φ700 mm, and a pair of two copper plates (heat sinks) is paired with each cartridge heater. As shown in FIG. 9, the heaters were attached so as to sandwich the heaters. The heat capacity of the heat sink at this time was 30 (J / K) per pair, and heat insulation was performed between adjacent heat sinks with a ceramic rod (insulator). The control of each cartridge heater is cycle control in which 5 seconds is one cycle.

  The molding conditions, dimensions of each part of the member used for molding, and dimensions at each position of the molded product are shown below.

<Molding conditions>
Set temperature Extruder C1 / C2 / C3 = 220/240/240
Gear pump 240 ℃
Die 240 ℃
Air ring blower output (inverter frequency) 20Hz
Seamless tube take-up speed 9 m / min.
Gear pump speed 30rpm
Gear pump metering gear teeth 60 pieces Air ring heater gain 3
<Dimensions of each part>
Inner diameter R1 of the first air outlet: 130 mm
Outer diameter R of the first air outlet: 150 mm
Outer diameter R2 of the second air outlet: 185 mm
Outer diameter D of annular die: 100 mm (inner diameter 98.4 mm)
Top height H1: 60mm of the first air outlet
Uppermost height of the second air outlet H2: 95 mm
Second air outlet top height H2
The diameter Dt of the tubular film at the position of +30 mm: 150 mm
Seamless tube diameter Db after solidification: 153 mm
Here, when controlling the heater disposed in the circumferential direction of the air ring, the temperature of the wind was measured in the circumferential direction by holding a thermocouple with a wire diameter of 50 μm over the air ring outlet, and the temperature was the lowest. The temperature was 28 ° C in the part and 55 ° C in the highest part. That is, the temperature difference of the wind was 27 ° C.
<Film thickness measurement results>
The film thickness in 100 circumferential directions of the obtained seamless tube was measured with the film thickness measuring device of FIG. 6, and Z indicating the above-described long-period film thickness unevenness and S indicating the short-period film thickness unevenness were obtained. As a result, the maximum value, the minimum value, and the standard deviation were as follows, both Z and S were small, and the variation was also small.

Z (shows long-period film thickness unevenness) S (shows short-cycle film thickness unevenness)
Maximum value 1.20 2.0
Minimum value 0.11 1.3
Standard deviation 0.25 0.24
In the tubular film obtained as described above, the one having the largest value of Z and the one having the largest value of S are selected, and the crease of the seamless tube is removed by the method of FIG. A rubber meandering preventing member having a height of 1 mm and a width of 5 mm was attached to one end of the surface with a double-sided tape to produce a seamless belt having a circumference of 482 mm. The heating temperature at this time was 180 degreeC. A belt having the largest Z was designated as a seamless belt 1, and a belt having the largest Z was designated as a seamless belt 2.
<Color shift evaluation test>
The produced seamless belt 1 was incorporated into the image forming apparatus of FIG. 1 as a transfer conveyance belt. The surface of the drive roller 21 has a rubber layer having a thickness of 1 mm, and its outer diameter is 22 mm. The winding angle of the belt around the driving roller was 130 °. The centers of rotation axes of adjacent photosensitive drums are 45 mm apart from each other.
In FIG. 1, 1-Y, 1-Y, 1-C, and 1-Bk are drum-shaped electrophotographic photosensitive members (hereinafter referred to as photosensitive drums) as image carriers, and have a predetermined circumference in the direction of the arrow. Driven at a speed (process speed).

  Hereinafter, a process of forming a first color component image (for example, a yellow color component image) will be described.

  The photosensitive drum 1-Y is uniformly charged to a predetermined polarity and potential by the primary charger 2 during the rotation process, and then subjected to image exposure 3 by an image exposure unit (not shown). In this way, an electrostatic latent image corresponding to the first color component image of the color image (in this example, the yellow color component image) is formed.

  Next, the electrostatic latent image is developed into a yellow component image by the first developing device (yellow color developing device 41). In this way, a first color (yellow) toner image is formed on the photosensitive drum 1-Y. Then, toner images of the second to fourth colors are also formed on the photosensitive drums 1-M, 1-C, 1-Bk at a predetermined timing.

  On the other hand, the transfer conveyance belt 24 has substantially the same peripheral speed as the photosensitive drum in the direction of the arrow or a predetermined peripheral speed difference with respect to the photosensitive drum (in many cases, the transfer conveyance belt is faster than the photosensitive drum). And is driven to rotate. Then, at a predetermined timing, the recording paper P is fed from the paper feed roller 11 to the transfer conveyance belt 24, the recording paper P is attracted to the transfer conveyance belt 24, and the recording paper P is rotated along with the rotation of the transfer conveyance belt. It will be transported.

  In the apparatus of FIG. 1, it is necessary to convey the recording paper P upward against gravity. In addition, there is no special means for increasing the adsorption force of the recording paper P to the transfer conveyance belt 24.

  For this reason, in the apparatus configuration as shown in FIG. 1, the adsorption is likely to be unstable, and the color shift is likely to occur. For this reason, if the transfer / convey belt 24 is not used with very little color misregistration due to speed fluctuation caused by film thickness unevenness, the color misregistration of the entire apparatus will be large.

  A transfer bias is applied to the transfer roller 22 through the bias power supply 28 when the recording paper P passes through the suction transfer nip of the belt (the portion where the photosensitive drum and the transfer roller 22 face each other via the transfer conveyance belt 24). As a result, the toner image on the photosensitive member is transferred onto the recording paper P.

  That is, a yellow toner image that is a first color component, a magenta toner image that is a second color component, a cyan toner image that is a third color component, and then a black toner that is a fourth color component. The toner images are sequentially laminated and transferred onto the recording paper P in the process of transporting the recording paper P. The transfer bias at this time is, for example, about −3 kV to +3 kV. The transfer / conveying belt 24 is cleaned by a so-called electrostatic cleaning method in which the toner on the transfer / conveying belt 24 is returned to the photosensitive member by applying a bias having the same polarity as the toner to the transfer roller 22. The photoreceptors 1-Y to 1-Bk have a charge transport layer of 20 μm, the potential (Vd) before image exposure is −700 (V), and the potential (V1) after image exposure is −150 (V). Primary charging and exposure were performed so that The transfer bias during image formation was +1000 (V). The above is the outline of the operation of the image forming apparatus.

  The moving speed of the transfer conveyance belt is 50 mm / second.

  The image forming apparatus shown in FIG. 1 was used to output the color misregistration measurement image output pattern shown in FIG. 14 to determine the color misregistration. The results are shown in Table 2. The color shift was evaluated as follows.

  As shown in FIG. 14, a horizontal line having a line width (line thickness) of 100 μm and a length of 5 mm is arranged in a horizontal row of four colors (yellow, cyan, magenta, black) at the center of A4 paper. When forming a line, the line was shifted by 2 mm in the vertical direction of the paper, and a total of 130 lines were drawn (about 20 mm on both upper and lower ends of the A4 paper was left blank, and an image was output to the central part 258 mm). In each row, with respect to the black horizontal line, the absolute value of how much the other three color horizontal lines are shifted in the vertical direction was measured. The maximum value measured in each row was defined as the color misregistration amount (μm) in the page. The image output environment was 23 ± 2 ° C. and 50 ± 10%.

  Criteria based on color misregistration amount are as follows.

200 μm or less: ◎
More than 200 μm and 220 μm or less: ○
More than 220 μm and 240 μm or less: Δ (Practical use possible)
Greater than 240 μm: × (not practical)
<Belt rotation durability test>
Next, the seamless belt 2 was attached to the belt rotation durability apparatus of FIG. 13, and a belt rotation durability test for 1000 hours was performed. The rotation speed of the belt is 100 mm / sec. The drive roller 320 and the tension roller 330 are both 22 mm in diameter. A drive roller having a rubber layer having a thickness of 1 mm was used, and a tension roller made of aluminum was used. Further, the tension spring 340 used was 1.8 kgf on the meandering prevention member side and 1.3 kgf on the anti-meandering prevention member side, and the belt tension was made to have a left-right difference.

  Here, after the durability test for 1000 hours, the belt was visually confirmed, and in the case where no defects such as cracks occurred, the rotation durability test for another 1000 hours was conducted in the same manner as described above.

  The durability of the belt was determined as follows.

No defects such as cracks after 2000 hours of rotation durability: ○
No failure at 1000 hours, but failure occurred at 2000 hours: △ (practical)
Failure occurred in less than 1000 hours: ×
[Examples 2 to 4]
The formulation was changed as shown in Table 1, and thermoplastic resin pellets were produced in the same manner as in Example 1.

  100 seamless tubes were produced for each of the produced thermoplastic resin pellets in the same manner as in Example 1 except that the inflation molding conditions were changed as shown in Table 2.

  In the same manner as in Example 1, the thickness of the seamless tube was measured to obtain Z and S. The results are shown in Table 3.

  The one with the largest value of Z and the one with the largest value of S were selected, and the crease of the seamless tube was removed by the method of FIG. 11 in the same manner as in Example 1, and a height of 1 mm was formed at one end of the inner peripheral surface. A rubber meandering prevention member having a width of 5 mm was pasted with a double-sided tape to produce a seamless belt having a circumference of 482 mm, and those having the largest Z were seamless belt 3 (Example 2) and seamless belt 5 (Example), respectively. 3), seamless belt 7 (Example 4), and those with the largest S were designated as seamless belt 4 (Example 2), seamless belt 6 (Example 3), and seamless belt 8 (Example 4), respectively. The heating temperatures at this time were 270 ° C. (Example 2), 180 ° C. (Example 3), and 290 ° C. (Example 4), respectively.

  Similarly to Example 1, the seamless belts 3, 5, and 7 were incorporated into the image forming apparatus of FIG. The results are shown in Table 3.

Further, seamless belts 4, 6, and 8 were attached to the belt rotating device shown in FIG. 13 in the same manner as in Example 1, and a belt rotation durability test was conducted. The results are shown in Table 3.
[Examples 5 to 12]
Thermoplastic resin pellets having the same composition as in Example 1 were produced in the same manner as in Example 1, and 100 seamless tubes were produced in the same manner as in Example 1 except that the inflation molding conditions were changed as shown in Table 2.

  In the same manner as in Example 1, the thickness of the seamless tube was measured to obtain Z and S. The results are shown in Table 3.

  The one with the largest value of Z and the one with the largest value of S were selected, and the crease of the seamless tube was removed by the method of FIG. 11 in the same manner as in Example 1, and a height of 1 mm was formed at one end of the inner peripheral surface. A rubber meandering prevention member having a width of 5 mm was pasted with a double-sided tape to produce a seamless belt having a circumference of 482 mm, and seamless belts 9 (Example 5) and seamless belts 11 (Examples) having the largest Z, respectively. 6), seamless belt 13 (Example 7), seamless belt 15 (Example 8), seamless belt 17 (Example 9), seamless belt 19 (Example 10), seamless belt 21 (Example 11), seamless belt 23 (Example 12), and those with the largest S were the seamless belt 10 (Example 5), the seamless belt 12 (Example 6), and the sheet, respectively. Les belt 14 (Example 7), seamless belt 16 (Example 8), seamless belt 18 (Example 9), seamless belt 20 (Example 10), seamless belt 22 (Example 11), seamless belt 24 (Example) Example 12).

  Similarly to Example 1, the seamless belts 9, 11, 13, 15, 17, 19, 19, and 23 were incorporated into the image forming apparatus of FIG. The results are shown in Table 3.

  Further, seamless belts 10, 12, 14, 16, 18, 20, 22, and 24 were attached to the belt rotating device of FIG. 13 in the same manner as in Example 1, and a belt rotation durability test was performed. The results are shown in Table 3.

<Comparative Examples 1-5>
Thermoplastic resin pellets having the same composition as in Example 1 were produced in the same manner as in Example 1, and 100 seamless tubes were produced in the same manner as in Example 1 except that the inflation molding conditions were changed as shown in Table 4.

  In the same manner as in Example 1, the thickness of the seamless tube was measured to obtain Z and S. The results are shown in Table 5.

  The one with the largest value of Z and the one with the largest value of S were selected, and the crease of the seamless tube was removed by the method of FIG. 11 in the same manner as in Example 1, and a height of 1 mm was formed at one end of the inner peripheral surface. A rubber meandering prevention member having a width of 5 mm was attached with a double-sided tape to produce a seamless belt having a circumference of 482 mm, and those having the largest Z were seamless belt 25 (Comparative Example 1) and seamless belt 27 (Comparative Example), respectively. 2), seamless belt 29 (Comparative Example 3), seamless belt 31 (Comparative Example 4), seamless belt 33 (Comparative Example 5), seamless belt 26 (Comparative Example 1), and seamless belt 28 (Comparative example 2), Seamless belt 30 (Comparative example 3), Seamless belt 32 (Comparative example 4), Seamless belt 34 (Comparative example 5)

  Similarly to Example 1, the seamless belts 25, 27, 29, 31, and 33 were incorporated into the image forming apparatus of FIG. The results are shown in Table 5.

  Further, the seamless belts 26, 28, 30, 32, and 34 were attached to the belt rotating device shown in FIG. The results are shown in Table 5.

2 is a cross-sectional view of a main part of an image forming apparatus having a transfer conveyance belt and a plurality of photoconductors. FIG. FIG. 3 is a cross-sectional view of a main part of an image forming apparatus having an intermediate transfer belt and a plurality of photoconductors. FIG. 4 is a cross-sectional view of a main part of a 4-pass image forming apparatus having an intermediate transfer belt. It is the schematic of an inflation molding machine. It is a figure which shows the relationship between an air blowing outlet and a tubular film. It is a thickness measuring machine schematic of a seamless tube. It is a figure explaining the diameter measuring method of a tubular film. It is the schematic of an air ring. It is a figure which shows a mode that a heater is inserted | pinched with a heat sink. It is a figure explaining the member which removes the crease | fold of a seamless tube. It is an image figure of the means to remove the crease | fold of a seamless tube. It is the figure which displayed the thickness of the circumferential direction of the seamless tube in the pie chart. It is a schematic diagram of a belt rotation endurance device. It is a figure which shows the image output pattern for a color shift measurement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 1-Y Yellow color photoconductor 1-M Magenta photoconductor 1-C Cyan photoconductor 1-Bk Black photoconductor 2 Primary charger 3 Exposure light 41 Yellow color developer 42 Magenta Color developing unit 43 Cyan developing unit 44 Black developing unit 5 Intermediate transfer belt 6 Primary transfer member 7 Secondary transfer roller 8 Secondary transfer counter roller 9 Belt cleaning member 11 Paper feed roller 13 Photoconductor cleaning member 15 Fixing unit 21 Drive roller 22 Transfer roller 23 Corona static eliminator 24 Transfer conveyor belt 25 Adsorption roller 26 Belt tension roller 27-33 Bias power supply 100 Single-screw extruder 110 Hopper 140 Annular die 150 Air intake / exhaust passage for tube diameter adjustment 160 Tubular film 170 Stabilizer 180 Pinch roll 190 Cutter 200 D Ring 201 first air outlet 202 and the second air outlet 210 the air supply port 220 Seamless tube 230 gear pump 301 cylindrical inner mold 302 cylindrical outer die 310 seamless belt 320 drive roller 330 tension roller 340 tension spring P recording paper

Claims (8)

A method of manufacturing a seamless tube for a seamless belt manufactured by inflation molding,
Using an extruder for melting and extruding a thermoplastic resin, an annular die having a diameter D, and an air ring having a plurality of air outlets, the relationship between the diameter D of the annular die and the diameter Db of the seamless tube is 1.1. ≦ Db / D ≦ 2.7, the height H1 [mm] of the uppermost portion of the first air outlet is 30 ≦ H1 ≦ 100, the outer diameter R of the uppermost portion of the first air outlet, The relationship with the diameter Dt of the tubular film at a position 30 mm above the height H2 of the uppermost portion of the air blowing port 2 is 0.8 ≦ R / Dt ≦ 1.2. A method for producing a seamless tube for a seamless belt, wherein the relationship between the diameter Dt of the tubular film and the diameter Db of the seamless tube at a position 30 mm above the height H2 is 0.8 ≦ Dt / Db.   The method for producing a seamless tube for a seamless belt according to claim 1, wherein the relationship between the diameter D of the annular die and the diameter Db of the seamless tube is 1.3≤Db / D≤2.0.   3. The method for producing a seamless tube for a seamless belt according to claim 1, wherein the relationship between the diameter Dt of the tubular film and the diameter Db of the seamless tube is 0.9 ≦ Dt / Db.   The seamless tube for a seamless belt according to any one of claims 1 to 3, wherein the seamless tube for a seamless belt contains at least a crystalline resin and a conductivity-imparting material.   The method for producing a seamless tube for a seamless belt according to claim 4, wherein the conductivity imparting material is a conductive filler.   The seamless air ring according to any one of claims 1 to 5, wherein the air ring is an air ring having a plurality of heaters in a circumferential direction of the cooling air flow path and capable of adjusting the temperature by dividing the cooling air. A method for producing a seamless tube for a belt.   The method for producing a seamless tube for a seamless belt according to any one of claims 1 to 6, wherein a gear pump is used between the extruder and the annular die.   The seamless tube take-up speed S [m / min. ] Is 5 <= S <= 20, The manufacturing method of the seamless tube for seamless belts in any one of Claims 1-7 characterized by the above-mentioned.

Images