JP2007007999A - Apparatus and method for manufacturing seamless belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for manufacturing a seamless belt which, in the seamless belt used for an intermediate transfer belt of a full color copying machine, do not generate the parting line and can obtain the seamless belt having good thickness precision. <P>SOLUTION: On the upper face of the mold body 10 formed into a seamless cylindrical shape, the upper split mold 20, which opens/closes while leaving the upper opening part partially unclosed, is installed. Above the upper split mold 20, the cutter 30 for cutting an extruded, cylindrical, molten resin is installed. On the lower face of the lower opening part 12 of the mold body 10, the lower mold 40 which opens/closes the lower opening part 12 is installed. The die 50 which cylindrically extrudes the molten resin into the mold body 10 is installed so as for its axis line to be agree with the axis line of the mold body 10. The die 50 is connected with the extruder 60 and also provided with the air pipe 70. The mold body 10, upper split mold 20, cutter 30 and lower mold 40 can move up and down as an integrated unit. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a seamless belt manufacturing apparatus and manufacturing method suitable for an intermediate transfer belt used in electrophotographic copying machines, printers, facsimiles, and the like.

  In recent years, full-color copying machines, color printers, and the like have come into practical use due to advances in color electrophotographic technology. In a full-color copying machine, a toner image formed on a photosensitive member is temporarily transferred onto an intermediate transfer belt, and then the image transferred onto the intermediate transfer belt is retransferred onto a copy sheet.

  The intermediate transfer belt is smooth (hereinafter referred to as “smoothness”) with a small surface roughness (small unevenness) in order to obtain a clear image free from image blurring and image misalignment. It is required that there is no variation (hereinafter referred to as “circumferential accuracy”) and that there is no variation in thickness (hereinafter referred to as “thickness accuracy”). That is, when the smoothness is poor, partial gaps are generated between the photosensitive member and the intermediate transfer belt, and between the intermediate transfer belt and the copy paper, resulting in image blur and image displacement. If the perimeter accuracy is poor, the printing position is shifted due to the running failure (meandering) of the intermediate transfer belt, or a partial gap is generated between the photoconductor and the intermediate transfer belt and the intermediate transfer belt and the copy paper due to slackness. Image blurring and image misalignment occur, and the belt may be damaged due to meandering of the belt. When the thickness accuracy is poor, the electrical resistance varies with the variation in thickness, and as a result, the image is shaded.

  As such an intermediate transfer belt, a seamless belt made of a thermoplastic resin is used. In order to manufacture a seamless belt, generally, a sheet-like film is bonded to form a tube (hereinafter referred to as “sticking”). A method of forming into a tube shape by centrifugal molding (hereinafter referred to as “centrifugal molding method”), an inflation molding method of forming into a tube shape by extrusion molding using an annular die, an extrusion blow molding method, etc. It was.

  Among these, the extrusion blow molding method is a method in which a thermoplastic resin melted from a die is extruded into a cylindrical shape to form a parison, and the molten parison is sandwiched between molds and air is blown into the interior for molding. The smoothness and circumference accuracy were good.

  As a method for producing a seamless belt by such a blow molding method, for example, a process of obtaining a cylinder by extruding a thermoplastic elastomer melt into a cylinder using an extruder, and a mold in which this cylinder is divided into two parts A process of sandwiching and enclosing with a mold having a mold and a mold cavity corresponding to the outer shape of the molded product inside, and injecting fluid into the enclosed cylinder, and the pressure of the fluid causes the outer peripheral surface of the cylinder to be A method for producing a conductive belt has been proposed, which includes a step of obtaining a molded product by inflating until the surface comes into contact, and a step of removing the molded product from the mold (see Patent Document 1).

JP 2000-141507 A

  However, in the extrusion blow molding method proposed in Patent Document 1 described above, a mold made of two divided members, that is, a so-called split mold is used to form a cylindrical shape. The molten resin entered the gap generated on the contact surface, and streaks (hereinafter referred to as “parting lines”) were formed in the axial direction of the outer surface of the cylindrical molded product. Therefore, in order to remove the parting line and smooth the surface, the surface has to be polished, which increases the number of processes and increases the cost.

  Moreover, in the extrusion blow molding method, good thickness accuracy could not be obtained. That is, in the extrusion blow molding method, the molten resin is extruded from the die in the vertical direction to form a parison, and the parison is stretched by its own weight (hereinafter referred to as “drawdown”). Accordingly, the thickness differs between the top and bottom of the parison due to drawdown, and as a result, the thickness of the molded product also varies.

  The present invention solves the above-described problems, and when a seamless belt is produced by an extrusion blow molding method, a seamless belt that does not generate a parting line and that has a good thickness accuracy can be obtained. An object of the present invention is to provide a manufacturing apparatus and a manufacturing method.

  The present inventors have intensively studied to achieve the above object, and paying attention to the fact that the parting line generated by the conventional split mold does not occur by using a seamless cylindrical mold. The invention has been completed.

  Also, in the conventional extrusion blow molding method, the parison is once formed and then expanded by blowing air, so that drawdown occurs during the formation of the parison, and the molten resin is cylindrical. The present invention has been completed by discovering that, when the resin is expanded by being blown with air at the same time as it is extruded, it can be prevented from being stretched by its own weight as much as possible.

  An apparatus for manufacturing a seamless belt according to claim 1 includes a mold body formed in a seamless cylindrical shape having openings on the top and bottom, a lower mold for opening and closing a lower opening of the mold body, and the mold. An upper split mold that opens and closes while leaving a part of the upper opening of the mold body, a die that extrudes the molten resin into a cylindrical shape inside the mold body, and air in the molten resin that is extruded cylindrically from the die Air blowing means for blowing air, and mold removing means for removing the molded body formed on the inner surface of the mold body, the mold body, the lower mold and the upper split mold or the die and air blowing At least one of the means can be moved up and down.

  According to a second aspect of the present invention, there is provided a seamless belt manufacturing method comprising: a mold arrangement step of closing a lower opening of a mold body formed in a seamless cylindrical shape having openings on the top and bottom with a lower mold; An extrusion process for extruding the resin into a cylindrical shape, an expansion process for blowing the air into the molten resin extruded into a cylindrical shape and inflating and pressing it to the inner surface of the mold body, and removing the molded body from the mold body It is characterized by having a demolding step of molding and a cutting step of cutting the upper and lower sides of the molded body demolded in the demolding step to form a cylinder.

  According to a third aspect of the present invention, there is provided a seamless belt manufacturing method comprising: a mold placement step of closing a lower opening of a mold body formed in a cylindrical shape having openings on the upper and lower sides with a lower mold; and an upper opening. A die placement step for placing the die in the vicinity of the lower mold, and extruding the molten resin into a cylindrical shape while expanding the space between the die and the lower mold, and simultaneously blowing air into the extruded cylindrical molten resin Extrusion-expansion process for obtaining a molded body by inflating and pressing to the inner surface of the mold body, a demolding process for demolding the molded body from the mold body, and cutting the upper and lower sides of the molded body demolded in the demolding process. And a cutting step for forming a cylindrical shape.

  A seamless belt manufacturing method according to a fourth aspect is the seamless belt manufacturing method according to the third aspect, wherein the mold body is formed in a seamless cylindrical shape.

  The seamless belt manufacturing method according to claim 5 is characterized in that, in the seamless belt manufacturing method according to claim 2, 3 or 4, the temperature of the mold body is lower by 5 to 20 ° C than the melting temperature of the molten resin. It is configured.

  The seamless belt manufacturing method according to claim 6 is the seamless belt manufacturing method according to claim 2, 3, 4, or 5, wherein the thickness of the portion of the molded body that is in close contact with the mold body (the thickness of the seamless belt). ) Is 30 to 400 μm.

  The seamless belt manufacturing method according to claim 7 is the seamless belt manufacturing method according to claim 2, 3, 4, 5 or 6, wherein the blow ratio is 1.1 to 2.0. ing.

  In the seamless belt manufacturing apparatus according to claim 1, since the mold body is formed in a seamless cylindrical shape and is not formed in a split mold as in the prior art, when the cylindrical molten resin is pressed No parting line is generated on the outer peripheral surface. Further, when the cylindrical molten resin is extruded, it is landed on the lower mold and fused to the lower mold, so that the inside of the molten resin can be made airtight and expanded by blowing air. The die can be introduced into the mold by opening and closing the mold, and the upper end of the cylindrical molten resin can be regulated.

  The die extrudes the molten resin into a cylindrical shape, and the air blowing means expands the cylindrical molten resin extruded from the die and presses it against the mold body. At this time, since at least one of the mold main body, the lower mold and the upper split mold, or the die and the air blowing means can move up and down, the mold main body or the like can be lowered or the die etc. Since air can be blown into the cylindrical molten resin from the air blowing means while extruding the molten resin into a cylindrical shape, the cylindrical molten resin can be expanded with a uniform thickness. Therefore, it is possible to eliminate uneven thickness due to so-called drawdown and obtain a molded body having a uniform thickness. And the molded object formed closely_contact | adhered to the metal mold | die main body can be easily demolded by a demolding means. A cylindrical seamless belt can be obtained by excising the upper and lower sides of the removed molded body, and the seamless belt has a uniform thickness.

  In the seamless belt manufacturing method according to claim 2, the lower opening of the mold body is closed with the lower mold in the mold arranging step, the molten resin is extruded into a cylindrical shape from the die in the extrusion step, and the cylinder is expanded in the expansion step. Air is blown into the molten resin extruded in the shape of the molten resin so as to be in expansion contact with the inner surface of the mold body to obtain a molded body. Therefore, since the seam does not contact the outer peripheral surface of the pressed cylindrical molten resin, it is possible to prevent a parting line from occurring in the molded body. Then, the molded body is demolded by the demolding process, and the molded body demolded in the cutting process can be cut up and down to obtain a cylindrical seamless belt. This seamless belt has no parting line and is flat. Is good.

  In the seamless belt manufacturing method according to the third aspect, the lower opening of the mold body is closed by the lower mold in the mold arranging step, and the die is arranged near the lower mold in the die arranging step. In the extrusion expansion process, the molten resin is extruded into a cylindrical shape while expanding the space between the die and the lower mold, and at the same time, air is blown into the extruded cylindrical molten resin so as to be inflated and pressed to the inner surface of the mold body. Thus, the cylindrical molten resin extruded from the die is immediately expanded. Therefore, the molten resin expands with the film thickness extruded from the die over the entire axial length of the mold body, so that the uneven thickness due to the so-called drawdown is eliminated, and a molded body having a uniform thickness is obtained. Then, the molded body is demolded by the demolding step, and further, the upper and lower sides of the molded body demolded in the cutting step can be cut to obtain a cylindrical seamless belt, and the seamless belt has a uniform thickness. .

  In addition, since the molten resin is extruded and immediately expanded, stretching unevenness does not occur, and even when a seamless belt having a small thickness is manufactured, the thickness can be accurately controlled. No wrinkles or pulling.

  In the seamless belt manufacturing method according to the fourth aspect, since the seamless cylindrical mold body is used, it is possible to prevent the generation of parting lines.

  In the seamless belt manufacturing method according to claim 5, the cylindrical molten resin extruded from the die is immediately expanded by lowering the temperature of the mold body 5 to 20 ° C. below the melting temperature of the molten resin. In this case, the molten resin does not draw down, and can be brought into close contact with the inner surface of the mold body, thereby improving the moldability.

  In the seamless belt manufacturing method according to claim 6, when the thickness of the portion of the molded body that is in close contact with the mold body is set to 30 to 400 μm, when used as an intermediate transfer belt for a full-color copying machine or the like, color misregistration is achieved. In addition to preventing wrinkles and wrinkles, smooth transportability can be obtained.

  In the seamless belt manufacturing method according to claim 7, by setting the blow ratio to 1.1 to 2.0, air is blown into the cylindrical molten resin extruded from the die to the inner surface of the mold body. When inflating and pressing, the inner surface of the mold is uniformly pressed, so that the thickness accuracy of the seamless belt can be improved.

  In the seamless belt manufacturing apparatus of the present invention, the mold body is formed in a seamless cylindrical shape having openings at the top and bottom, that is, if it is not constituted by a split mold, its material and dimensions Etc. are not particularly limited. The mold body is preferably provided with heating means for adjusting to a desired temperature. The heating means can be performed, for example, by providing a serpentine tube inside the mold body and circulating a heated fluid. Moreover, it is preferable that a heating means can adjust the management width | variety of heating temperature in the range of +/- 1-3 degreeC. Furthermore, it is preferable to provide a cooling means for cooling the mold body.

  A lower mold that opens and closes the lower opening is provided at the lower end of the mold body. This lower mold is for landing and fixing a cylindrical molten resin. It opens at the time of molding. The lower mold may be a single mold or a split mold including two split blocks.

  The upper part of the mold body is provided with an upper split mold that opens and closes with a part of the upper opening. When the upper split mold is opened, the die and air blowing means are inserted into the mold body. The upper end of the cylindrical molten resin is regulated in a closed state.

  It is preferable to provide a demolding means for demolding the molded body on the inner surface of the mold body. As this mold demolding means, for example, a slight groove is formed in the axial direction at the lower end of the inner surface of the mold body. Can be released from the close contact between the molded body and the inner surface of the mold body.

The die extrudes the molten resin in a cylindrical shape inside the mold body, and the air blowing means blows air into the molten resin extruded in a cylindrical shape from the die. The die may be a general one used for blow molding, but preferably has a die structure that matches the material suitable for the purpose and has a good thickness adjustment,
Further, it may be a single layer die or a multilayer die. The extruder connected to the die may be a single-screw extruder using raw materials mixed in advance using a twin-screw kneading extruder, or a twin-screw extruder excellent in direct mixing. In addition, a single head type, a twin head type, and a multi head type can be used, and further, a slide method and a rotary method can be used as a mold conveyance method.

  At least one of the mold body, lower mold and upper split mold or die and air blowing means can move up and down, the mold body can move up and down, the die can move up and down, and both There are three modes that can move up and down. By allowing at least one of these to move up and down, the relative position of the die inside the mold body can be changed. That is, the tip of the die can be arbitrarily positioned from the lower end to the upper end of the mold body.

  In the first seamless belt manufacturing method of the present invention (Claim 2), a mold body formed in a seamless cylindrical shape is used, which is different from a mold body using a conventional split mold. . That is, by replacing the split mold with a seamless mold body, a conventionally known blow molding machine can be used, and various molding conditions are the same.

  In the second seamless belt manufacturing method of the present invention (Claim 3), in the extrusion expansion step, the molten resin is extruded into a cylindrical shape while expanding the space between the die and the lower mold, and simultaneously extruded into a cylindrical shape. Air is blown into the molten resin and inflated and pressed to the inner surface of the mold body. Therefore, the thickness of the seamless belt can be set to a desired thickness by appropriately adjusting the extrusion amount of the molten resin, the speed of spreading between the die and the lower mold, and the blow ratio. Moreover, it is preferable that the pressure of the air at the time of inflating and pressure-contacting to the inner surface of a die main body by blowing air in cylindrical molten resin is 0.3-0.5 MPa. If the pressure is less than 0.3 MPa, the adhesion between the extruded molten resin and the mold is poor, and the thickness accuracy and circumference accuracy are deteriorated. Moreover, when it exceeds 0.5 Mpa, the extruded molten resin will expand more than necessary.

  At the start of the extrusion of the molten resin from the die, the distance between the discharge port of the die and the lower mold is preferably 5 to 50 mm, and more preferably 10 to 20 mm. If the distance between the die outlet and the lower mold is less than 5 mm, the extruded molten resin adheres to the vicinity of the die outlet, and then the molten resin film extruded from the die causes scratches and streaks. Thickness accuracy deteriorates. On the other hand, if it exceeds 50 mm, the molten resin extruded from the die tends to be drawn down, and the thickness accuracy deteriorates. Furthermore, since the adhesiveness between the mold and the resin is poor and the pressure is not uniformly pressed, the circumferential length accuracy is deteriorated.

  The gap between the die and the lower mold can be increased by raising the die, or by lowering the mold body and lower mold, and raising the die and lowering the mold body and lower mold. You may carry out by descending. The mold body may be formed in a seamless cylindrical shape or may be formed of a conventional split mold. In the case of using a mold body composed of split molds, the second seamless belt manufacturing method of the present invention is implemented by allowing at least one of the mold body or die to move up and down in a conventional blow molding machine. be able to. The moving speed of the vertical movement is preferably 2 to 20 m / min, and more preferably 3 to 10 m / min. If the moving speed is less than 2 m / min, drawdown is likely to occur. Moreover, when it exceeds 20 m / min, thickness accuracy will deteriorate.

  In the first and second seamless belt manufacturing methods, the temperature of the mold body is preferably 5 to 20 ° C lower than the melting temperature of the molten resin, and more preferably 7 to 9 ° C lower. When the temperature of the mold main body is not 5 ° C. lower than the melting temperature of the molten resin, the molten resin extruded from the die is easily drawn down, and the thickness accuracy is deteriorated. Furthermore, since the adhesiveness between the mold and the resin is poor and the pressure is not uniformly pressed, the circumferential length accuracy is deteriorated. Moreover, when it becomes 20 degrees C or more, when the molten resin extruded from die | dye contacts a metal mold | die, it will be cooled rapidly, adhesiveness with a metal mold | die will deteriorate, thickness accuracy and the smoothness of a seamless belt surface will deteriorate. .

  The blow ratio in the method for producing the first and second seamless belts is preferably 1.1 to 2.0, and more preferably 1.3 to 1.5. If the blow ratio is less than 1.1, the die cannot be inserted into the mold. On the other hand, if the blow ratio exceeds 2.0, the time until the molten resin extruded from the die comes into contact with the mold becomes long, so that the adhesiveness with the mold becomes poor, and the thickness accuracy of the seamless belt deteriorates.

  In the present invention, the seamless belt may be a single layer or a multilayer of two or more layers. The thermoplastic resin used for the seamless belt is not particularly limited, and examples thereof include polyolefin resins such as polyethylene and polypropylene; fluorine resins such as polyvinyl fluoride, ethylene-tetrafluoroethylene and polyvinylidene fluoride; polyethylene terephthalate and polybutylene. Polyester resins such as terephthalate; polyamide resins; vinyl chloride resins; ABS resins; polymethyl methacrylate; polycarbonates; polyether ether ketones; polyacrylonitriles; polyacetals; and hydrogenated styrene called thermoplastic elastomers -Butadiene copolymer, polyether ester, thermoplastic polyurethane and the like can be used, and these thermoplastic resins may be used alone or in admixture of two or more.

  Among the above thermoplastic resins, fluororesins have a high dielectric constant and are excellent in flame retardancy, non-adhesiveness, non-contamination, low friction, chemical resistance, ozone resistance, etc. It is particularly suitable for use as an electrophotographic member such as a printer and a facsimile. Fluorine-based resins include polyvinyl fluoride, polyvinylidene fluoride, ethylene trifluoride-vinylidene fluoride copolymer, vinylidene fluoride-tetrafluoroethylene copolymer, ethylene trifluoride-vinylidene fluoride-6 Propylene fluoride copolymer, vinylidene fluoride-tetrafluoroethylene-hexafluoropropylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-ethylene trifluoride chloroethylene copolymer and polyfluoride Graft copolymer with vinylidene fluoride, graft copolymer of vinylidene fluoride-hexafluoropropylene copolymer and polyvinylidene fluoride, ethylene tetrafluoride-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene Copolymer, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polytrifluoride Ethylene, and the like. Of these, vinylidene fluoride homopolymers and copolymers thereof are particularly preferred in terms of moldability.

At least one layer of the belt can be a semiconductive layer having a volume resistivity in the range of 1 × 10 ⁵ Ω · cm to 1 × 10 ¹⁴ Ω · cm. By using such a semiconductive layer, it can be usefully used as an intermediate transfer belt, a transfer conveyance belt, and the like, and can also be usefully used as a surface material for a transfer roll.

  Some thermoplastic synthetic resins, such as thermoplastic elastomers, exhibit semiconductivity by themselves, but in order to impart semiconductivity to layers made of thermoplastic synthetic resins that do not exhibit such properties, conductive Add agent.

  As the conductive agent, carbon black, grafted carbon black, carbon fiber, metal oxide, metal powder, electronic conductive material such as metal fiber, polymer containing polyethylene oxide chain, polymer having ammonium salt in the side chain, Examples include ion-conductive materials such as alkali metal-containing ionomers, alkali metal salts, fluoroboric acid of alkyl quaternary ammonium, and alkyl quaternary ammonium salts. By adding one or more of these materials, the above-mentioned thermoplastic synthetic resin is semiconductive. Sex can be imparted. Moreover, graphite fiber, glass fiber, etc. which coated the electrically conductive agent can also be used.

  Of the electron conductive materials, carbon black is preferred because the resistance decreases with a small addition. Among ion-conductive materials, a polymer containing a polyethylene oxide chain is preferable because the influence on the electrical resistance due to the use environment (temperature, humidity) is small.

  Examples of the carbon black include acetylene black, furnace black, and channel black. Among them, acetylene black and ketjen black, which is a kind of furnace black, are preferable from the viewpoint that semiconductivity can be imparted with a small addition amount. . The amount of carbon black added varies depending on the type of carbon black, but in the case of acetylene black, it preferably occupies 3 to 25% by weight of the total weight, and in the case of ketjen black occupies 1 to 10% by weight. Is preferred. If it is less than the above range, semiconductivity cannot be imparted, and if it exceeds the above range, not only the processability at the time of extrusion molding is bad, but the strength of the product is lowered, which is not preferable.

  In order to reduce the variation in resistance of the seamless belt, it is preferable to use carbon black and a polymer having a polyethylene oxide chain as a conductive agent, as described in JP-A-7-113029. The amount of carbon black added is preferably in the same range as described above.

  For the same purpose, surface-treated carbon black, for example, grafted carbon black described in JP-A-11-29678 can be used. In the case of grafted carbon black, the addition amount in the above range is preferable in terms of carbon black weight.

  Further, for the same purpose, as described in JP-A-8-165395, a polymer having a polyethylene oxide chain as a conductive agent (including a copolymer thereof) and an alkali metal salt such as lithium perchlorate It is also preferable to use an ion electrolyte typified by The addition amount of the polymer having a polyethylene oxide chain preferably occupies 0.3 to 25% by weight in the total weight. On the other hand, when the ionic electrolyte is an alkali metal salt, the amount added is preferably 0.01 to 5% by weight, more preferably 0.05 to 4% by weight in the total weight.

  Various additives can be added to the seamless belt as necessary within a range that does not adversely affect the seamless belt. For example, coloring agents for coloring belts, glass fibers as reinforcing agents, antistatic agents for reducing triboelectric chargeability, hygroscopic agents, antiblocking agents, lubricants, processing aids, etc. may be added. it can.

  The thickness of the seamless belt is preferably 30 to 400 μm, more preferably 80 to 200 μm, and most preferably 100 to 150 μm. When the thickness is less than 30 μm, when the seamless belt is stretched between rolls and driven with tension, it stretches and causes color shift or wrinkles. When the thickness exceeds 400 μm, the seamless belt Flexibility is impaired, smooth transportability cannot be obtained, and color misregistration is likely to occur.

  The use of the seamless belt in the present invention is not particularly limited, but an intermediate transfer belt used for electrophotographic copying machines, printers, facsimiles, etc., which requires high smoothness, thickness accuracy and circumference accuracy, It is suitable for a transfer conveyance belt.

  An embodiment of a seamless belt manufacturing apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 is a partially cut front view of a seamless belt manufacturing apparatus, FIG. 2 is a front view of a state where the molten resin is extruded, FIG. 3 is a front view of a state where the molten resin is expanded halfway, and FIG. FIG. 5 is a front view of the state before the molten resin is cut, FIG. 6 is a front view of the state in which the molten resin is cut, and FIG. It is a front view which shows the state which cuts up and down and obtains a seamless belt.

  In FIG. 1, reference numeral 10 denotes a mold body formed in a seamless cylindrical shape. The inner surface of the mold body 10 is mirror-finished, and the upper and lower openings 11 and the lower opening are opened up and down. 12 Further, a serpentine tube (not shown) as a heating means is provided inside the mold body 10 and a cooling means (not shown) for cooling the mold body 10 is provided.

  An upper split mold 20 is provided on the upper surface of the mold main body 10 so as to open with a part of the upper opening, and the upper split mold 20 is provided so that the upper opening 11 of the mold main body is slidable. It is composed of two split-type blocks 21. The split block 21 is formed in a semicircular shape having a larger diameter than the mold body 10, and a substantially semicircular cutout portion 22 is formed at the center thereof. Then, when the split block 21 is slid to close the upper opening 11, the cutout portions 22 of the split blocks 21 are combined to form a substantially circular hole. Further, a cutter 30 for cutting the extruded cylindrical molten resin is provided above the upper split mold 20, and the cutter 30 is provided with two cutter blades that are provided so as to freely advance and retract in the horizontal direction. 31 is comprised.

  A lower mold 40 that opens and closes the lower opening 12 is provided on the lower surface of the lower opening 12 of the mold body 10. The lower mold 40 is composed of two split mold blocks 41 slidably provided in the lower opening 12 of the mold main body. The split mold block 41 has a diameter larger than that of the mold main body 10. It has a semicircular shape. In addition, near the lower end of the inner surface of the mold body 10, air blowing means (not shown) is provided for blowing the air between the inner surface of the mold body 10 and a seamless belt as a molded product. ing.

  A die 50 for extruding a molten resin in a cylindrical shape is provided in the mold body 10 so that the axis of the mold body 10 and the axis coincide with each other. An extruder 60 is connected to the die 50, and an air pipe 70 is provided for injecting air into the cylindrical molten resin extruded by the die 50 and expanding the air pipe 70. Is connected to an air supply source (not shown).

  Further, the mold body 10, the upper split mold 20, the cutter 30 and the lower mold 40 are configured to be integrally movable up and down. And when the mold main body 10 etc. rises to the highest point, the upper surface of the lower split mold 40 is set so as to be located about 5-50 mm below the lower surface of the die 50, and the mold main body 10 etc. The cutter 30 is set so as to be positioned below the lower surface of the air pipe 70 when lowered to the lowest point.

  Further, a control unit (not shown) is provided for controlling the extrusion amount of the molten resin from the die 50, the lowering speed of the mold body 10, and the like, and the control unit controls the extrusion amount and the lowering speed. At the same time, a seamless belt with a predetermined thickness is manufactured by adjusting the blow ratio.

  In order to manufacture a seamless belt with the seamless belt manufacturing apparatus as described above, first, as shown in FIG. 2, the mold body 10, the upper split mold 20, the cutter 30 and the lower split mold 40 are raised to the highest point. . At this time, the upper split mold 20 is opened and the lower split mold 40 is closed. Then, the die 50 enters the inside of the mold main body 10, and the distance a between the lower surface thereof and the upper surface of the lower split mold 40 is 5 to 50 mm. The mold body 10 is heated by a heating means (a temperature lower by 5 to 20 ° C. than the melting temperature of the molten resin).

  Next, the extruder 60 (extruder temperature: 200 to 300 ° C.) is driven to extrude the molten resin from the die 50 into a cylindrical shape. Then, the molten resin 80 extruded in a cylindrical shape is landed and fused on the lower split mold 40, and the inside becomes an airtight state. In this state, when the mold body 10 or the like is lowered at a predetermined speed (downward speed: 3 to 20 m / min) and air is blown into the molten resin 70 from the air pipe 70, the molten resin extruded from the die 50 is used. 80 is immediately expanded, and as shown in FIG. 3, the molten resin 80 is pressed against the inner surface of the mold main body 10, and when the mold main body 10 is further lowered, as shown in FIG. The molten resin 80 is press-contacted to the entire inner surface of 10, and a molded body 90 having a cylindrical middle part and closed upper and lower ends is molded. In addition, the cylindrical intermediate part which cut off the upper and lower sides of this molded object 90 becomes a seamless belt. Therefore, since the condition of the thickness of the molten resin at the time of expansion is always constant, the thickness of the formed seamless belt in the axial direction is uniform, and no parting line is generated.

  Further, as shown in FIG. 5, the mold body 10 is lowered until the air pipe 70 escapes, and the upper split mold 20 is closed. Then, as shown by a two-dot chain line in the figure, the molten resin 80 is cut by the cutter 30 in advance. Is cut off from the die 50. Thereafter, the mold body 10 is cooled by a cooling means, and the upper split mold 20 and the lower split mold 40 are opened as shown in FIG. The air is blown between the inner surface of the mold 10 and the molded body 90 is peeled off from the mold body 10. And as shown in FIG. 7, the upper and lower sides of the taken-out molded object 90 are excised, the cylindrical intermediate part can be taken out, and the seamless belt 100 can be obtained.

  It should be noted that a twin-head or multi-head die can be used to form a plurality of molded bodies at a time. Alternatively, a plurality of mold bodies can be conveyed by a slide method or a rotary method, You may enable it to shape | mold continuously.

[compound]
<Compound A>
A premixed mixture of 100 parts by weight of polyvinylidene fluoride and 8 parts by weight of conductive carbon black was kneaded using a twin screw extruder to obtain a conductive compound.
<Compound B>
A premixed mixture of 100 parts by weight of polyvinylidene fluoride and 10 parts by weight of conductive carbon black was kneaded using a twin screw extruder to obtain a conductive compound.

[Example 1]
Using Compound A, a seamless belt having a thickness of 100 μm was manufactured using the seamless belt manufacturing apparatus shown in FIG. As the extruder, “Mode D-50” manufactured by Modern Machinery Co., Ltd. is used, a single-layer die (caliber: 200 mm) is used as the die, a die body having an inner diameter: 255 mm, and a blow ratio: about 1. 28.

  The lowering speed of the mold body was 3 m / min, and the initial interval between the die discharge port and the lower split mold was 10 mm.

  The obtained seamless belt was of high quality with no parting line, thickness variation of ± 3 μm, circumferential length variation of ± 0.2 mm, and belt surface roughness Rz of 0.3 μm. The obtained seamless belt was mounted on a full-color electrophotographic apparatus and subjected to a full-color print image test without performing secondary correction processing. As a result, a clear image was obtained.

[Example 2]
A seamless belt having a thickness of 200 μm was manufactured under the same apparatus and conditions as in Example 1.

  The obtained seamless belt was of high quality with no parting line, thickness variation of ± 5 μm, circumferential length variation of ± 0.2 mm, and belt surface roughness Rz of 0.3 μm. The obtained seamless belt was mounted on a full-color electrophotographic apparatus and subjected to a full-color print image test without performing secondary correction processing. As a result, a clear image was obtained.

[Example 3]
Using Compound A, a seamless belt having a thickness of 100 μm was manufactured using the seamless belt manufacturing apparatus shown in FIG. As the extruder, “Mode D-50” manufactured by Modern Machinery Co., Ltd. is used. As the die, a single-layer die (caliber: 100 mm) is used. The die body has an inner diameter of 127 mm. The blow ratio is 1.27. It was.

  The lowering speed of the mold body was 3 m / min, and the initial interval between the die discharge port and the lower split mold was 10 mm.

  The obtained seamless belt was of high quality with no parting line, thickness variation of ± 3 μm, circumferential length variation of ± 0.2 mm, and belt surface roughness Rz of 0.3 μm. The obtained seamless belt was mounted on a full-color electrophotographic apparatus and subjected to a full-color print image test without performing secondary correction processing. As a result, a clear image was obtained.

[Example 4]
A seamless belt having a thickness of 200 μm was manufactured under the same apparatus and conditions as in Example 3.

  The obtained seamless belt was of high quality with no parting line, thickness variation of ± 5 μm, circumferential length variation of ± 0.2 mm, and belt surface roughness Rz of 0.3 μm. The obtained seamless belt was mounted on a full-color electrophotographic apparatus and subjected to a full-color print image test without performing secondary correction processing. As a result, a clear image was obtained.

[Example 5]
Polyvinylidene fluoride and compound B, to which no conductive agent is added, are used in the same apparatus as the seamless belt manufacturing apparatus shown in FIG. A two-layer seamless belt having a compound B layer (150 μm) as the inner layer and a total thickness of 200 μm was produced. Two extruders “Type D-40” manufactured by Modern Machinery Co., Ltd. are used as the extruder, a two-layer die (caliber: 100 mm) is used as the die, a die body having an inner diameter of 127 mm, and a blow ratio: 1 .27.

  The lowering speed of the mold body was 3 m / min, and the initial interval between the die discharge port and the lower split mold was 10 mm.

  The obtained seamless belt was of high quality with no parting line, thickness variation of ± 6 μm, circumferential length variation of ± 0.2 mm, and belt surface roughness Rz of 0.3 μm. The obtained seamless belt was mounted on a full-color electrophotographic apparatus and subjected to a full-color print image test without performing secondary correction processing. As a result, a clear image was obtained.

[Conventional example 1]
A seamless belt having a thickness of 100 μm was manufactured by a conventional method (a method in which air is blown and expanded after forming a parison) in an apparatus using Compound A and a conventional mold body having a split mold. The extruder ("Mode D-50" manufactured by Modern Machinery Co., Ltd.) and the die (caliber: 100 mm) are the same as in Example 3, and the mold body consisting of the split mold has the inner diameter: 255 mm. The ratio was 2.55.

  The obtained seamless belt had a high quality with a parting line, a thickness variation of ± 25 μm, a circumferential variation of ± 0.8 mm, and a belt surface roughness Rz of 1.5 μm. In addition, the obtained seamless belt was mounted on a full-color electrophotographic apparatus without performing secondary correction processing, and as a result of performing a full-color print image test, the thickness accuracy was very poor, so color misregistration occurred frequently, resulting in parting lines. The resulting deviation occurred, and the toner was scattered much and a clear image could not be obtained.

[Presence / absence of parting line]
The outer peripheral surface of the seamless belt was determined by visual observation.

[Thickness variation measurement]
Measuring instrument: Anritsu "Film Sickness Tester KG601B"
The thickness of the belt in the circumferential direction was continuously measured, and the average thickness and thickness variation were determined.

[Measurement of circumference variation]
The belt was cut open, the length was measured in the circumferential direction with a JIS grade 1 stainless steel ruler, and the variation in the circumference was determined.

[Surface roughness (Rz) measurement]
Measuring instrument: Tokyo Seimitsu Co., Ltd. “Surfcom 570A”
Rz (10-point average roughness): Measured according to JIS B 0601-1982.

[Image test]
The obtained image was visually observed to determine its sharpness.

[Evaluation]
Comparing Conventional Example 1 and Examples 1 and 3 having the same thickness as Conventional Example 1, Examples 1 and 3 have no parting line, and have a thickness variation of about 1/8. It was confirmed that the variation was ¼ and the surface roughness (Rz) was ５, which was very good, and also good in the image test.

1 is a partially cut front view of an embodiment of a seamless belt manufacturing apparatus according to the present invention. The front view of the state which extruded the molten resin in one Embodiment of the manufacturing apparatus of the seamless belt by this invention The front view of the state which expanded the molten resin to the middle in one Embodiment of the manufacturing apparatus of the seamless belt by this invention The front view of the state which expanded the molten resin to the last in one Embodiment of the manufacturing apparatus of the seamless belt by this invention The front view of the state before cut | disconnecting molten resin in one Embodiment of the manufacturing apparatus of the seamless belt by this invention The front view of the state which cut | disconnected the molten resin in one Embodiment of the manufacturing apparatus of the seamless belt by this invention Front view showing a state where a seamless belt is obtained by cutting the top and bottom of the molded body

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Mold body 20 Upper split mold 30 Cutter 40 Lower split mold 50 Die 60 Extruder 70 Air pipe 80 Molten resin 90 Molded body 100 Seamless belt

Claims (7)

Mold body formed in a seamless cylindrical shape with openings at the top and bottom, a lower mold for opening and closing the lower opening of the mold body, and opening and closing with a part of the upper opening of the mold body An upper split mold, a die for extruding a molten resin into a cylindrical shape inside the mold body, an air blowing means for blowing air into the molten resin extruded from the die into a cylindrical shape, and the mold body A mold removing means for removing the molded body formed on the inner surface of the mold, and at least one of the mold main body, the lower mold and the upper split mold or the die and the air blowing means is movable up and down. A seamless belt manufacturing device. A mold placing step for closing a lower opening of a mold body formed in a seamless cylindrical shape having openings on the upper and lower sides with a lower mold, an extrusion step for extruding molten resin from a die into a cylindrical shape, and a cylinder An expansion process for obtaining a molded body by blowing air into the molten resin that has been extruded into an inner surface of the mold body to obtain a molded body, a demolding process for demolding the molded body from the mold body, and the demolding process. A method for producing a seamless belt, comprising: a cutting step of cutting the upper and lower sides of the removed molded body into a cylindrical shape. A die placement step for closing a lower opening of a die body formed in a cylindrical shape having openings on the upper and lower sides with a lower die, and a die placement step for placing a die near the lower die through the upper opening. The molten resin is extruded into a cylindrical shape while expanding the space between the die and the lower mold, and at the same time, air is blown into the extruded cylindrical molten resin so as to be inflated and pressed to the inner surface of the mold body. An extruding expansion step for obtaining a mold, a demolding step for demolding the molded body from the mold body, and a cutting step for cutting the upper and lower sides of the molded body demolded in the demolding step to form a cylinder. A method for producing a seamless belt characterized by the above. 4. The method of manufacturing a seamless belt according to claim 3, wherein the mold body is formed in a seamless cylindrical shape. The process for producing a seamless belt according to claim 2, 3 or 4, wherein the temperature of the mold body is 5 to 20 ° C lower than the melting temperature of the molten resin. The method for producing a seamless belt according to claim 2, 3, 4, or 5, wherein the thickness of the portion of the molded body that is in close contact with the mold body is 30 to 400 µm. The process for producing a seamless belt according to claim 2, 3, 4, 5, or 6, wherein the blow ratio is 1.1 to 2.0.

Images