JP2007310022A - Endless belt, and image forming apparatus with endless belt - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endless belt in which a joint portion has high flexibility equal to that of a non-joint portion and also has an electric characteristic equal to that of a peripheral portion. <P>SOLUTION: The endless belt is made of a sheet member containing a thermoplastic resin and fiber-like filler. In the endless belt, the two edges of the sheet member have a plurality of fitting portions to be fitted to each other, and has a joint portion to be joined with the plurality of fitting portions in endless. The joint portion is bonded with an adhesive member containing the same thermoplastic resin and fiber-like filler as those incorporated in the sheet member. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an endless belt suitably used for an electrophotographic apparatus such as an electrophotographic copying machine, a laser beam printer, a facsimile, and a composite apparatus thereof, and an image forming apparatus including the endless belt.

  A seam belt is used as a transfer belt used in an electrostatic photographic apparatus such as an electrophotographic apparatus from the viewpoint of economy.

  As a method for joining a seam belt and a method for producing a transfer belt of an image forming apparatus, there is a method in which both ends of a film-like belt base material to be joined are overlapped (for example, Patent Document 1). However, when bonded in an overlapping manner, the thickness of the bonded portion becomes several tens of μm greater than that of the non-bonded portion, which causes problems such as defective transfer and excessive cleaning of the cleaning member. Further, it takes a considerable time to polish and align the thickness with the non-joined portion, and high polishing accuracy is also required.

  As a means for providing a seam belt having no step and excellent tensile strength, a method has been proposed in which a seam shape is fitted and bonded with an adhesive containing the same resin as the base material (Patent Document 2). However, in this method, since a powdery adhesive is used, it is difficult to make the electrical characteristics of the joint portion uniform as in the peripheral portion. When an image is formed at the joint portion, a good quality is obtained. The image quality may not be obtained.

  There has been proposed a belt manufacturing method in which a puzzle-cut joint is joined with an adhesive containing polyamide and a doped metal oxide filler, and printing defects do not occur even when an image is formed on the joint ( Patent Document 3). However, because the seam joined with an adhesive made of a material different from the base material does not reach the same level of flexibility as the peripheral part, repeated loading is performed with the tension roll part that has been reduced in size in association with the miniaturization of copiers and printers. Depending on the bending stress that is applied, it may cause breakage, deformation, and puzzle popping.

JP-A-6-43768 JP-A-10-175256 JP 2003-186274 A

  An object of the present invention is to solve various problems in the prior art and achieve the following objects. That is, an object of the present invention is to improve the bendability of the joint portion of the seam belt and to make the electrical characteristics equal to those of the peripheral portion, so that even if an image is formed on the joint portion, the image does not have a defect. And an image forming apparatus including the endless belt.

  As a result of intensive research to solve the above problems, the present inventors made the belt base material and the adhesive film the same thermoplastic resin, and matched the electrical characteristics of the joint portion with the peripheral portion, thereby joining them. In order to complete the present invention, it is possible to provide an image having no defects even in the part, and that a belt having high bending resistance can be obtained by uniformly dispersing a fibrous filler in the base material and the adhesive film. It came.

That is, the present invention
<1> A sheet-like member containing a thermoplastic resin and a fiber-shaped filler, and two end portions of the sheet-like member have a plurality of fitting portions that are fitted to each other. A joint portion joined endlessly by the fitting portion, and the joint portion contains the same kind of thermoplastic resin and the same kind of fibrous filler as those contained in the sheet-like member. This is an endless belt bonded by an adhesive member.

  <2> An image carrier, a charging unit for charging the surface of the image carrier, a latent image forming unit for forming a latent image on the surface of the image carrier, and developing the latent image with toner to form a toner image An image forming apparatus comprising: a developing unit that performs transfer; and a transfer unit that transfers the toner image onto a recording medium, wherein the transfer unit includes a thermoplastic resin and a fibrous filler. The two end portions of the sheet-like member have a plurality of fitting portions fitted to each other, and have a joining portion joined endlessly by the plurality of fitting portions, the joining portion Is an image forming apparatus provided with an endless belt that is bonded by an adhesive member that contains the same thermoplastic resin and the same fiber-shaped filler that are contained in the sheet-like member.

  The present invention has a joint having high flexibility equivalent to that of a sheet-like member and having an electrical property equivalent to that of the sheet-like member, so that even if an image is formed on the joint, an image is defective. It is possible to provide an endless belt having substantially the same performance as that of a sheet-like member, and an image forming apparatus including the endless belt.

  Embodiments of the present invention will be described below.

<Endless belt>
The endless belt of the present invention is composed of a sheet-like member containing a thermoplastic resin and a fibrous filler, and two end portions of the sheet-like member have a plurality of fitting portions that are fitted to each other. A joint part joined endlessly by the plurality of fitting parts, and the joint part is the same kind of thermoplastic resin as that contained in the sheet-like member, and the same kind of fibrous filler. It is adhered by an adhesive member containing

  In other words, the endless belt of the present invention has a shape in which one end and the other end of a sheet-like member containing a thermoplastic resin and a fibrous filler are fitted, and the one end and the other end. The joint part in which the joint with the part is formed is joined by an adhesive member containing the same thermoplastic resin and fibrous filler as those contained in the sheet-like member. As a result, the mechanical and electrical characteristics of the joint are equivalent to those of the peripheral part. Here, the content of the fiber-shaped filler contained in the adhesive member is most preferably the same as that of the sheet-like member, but the content of the fiber-shaped filler contained in the sheet-like member is ± The content may be in the range of 10% by mass.

  At both ends of the sheet-like member, there are formed fitting portions that can be joined to each other and cannot be detached in the center direction of the sheet-like member in the joined state. As the fitting portions formed at both ends of the sheet-like member, there is no particular limitation as long as it has a shape that can be joined to each other and is not removable in the center direction of the sheet-like member in the joined state, For example, one having a puzzle cut pattern with a plurality of substantially circular protrusions 2a and a plurality of bases 2b having a narrower width as shown in FIG. 1, as shown in FIG. 3 having a puzzle cut pattern with a plurality of substantially semicircular protrusions 2a and a plurality of bases 2b having a narrower width than that, the width of the tip as shown in FIG. A puzzle cut pattern having a plurality of projecting portions 2a each having a projecting piece 2c projecting in the width direction of the belt-like member as shown in FIG. Pa A puzzle cut pattern is formed at one end of the belt-like member, and a plurality of substantially rectangular protruding portions 2d provided with notches 2e having substantially the same size and shape as the protruding pieces 2c are formed at the other end. And so on.

  When the fitting portions formed at both ends of the front sheet-like member are fitted to each other in a state where the sheet-like member is not twisted, an endless belt is formed. At this time, as described above, the fitting portion is provided with a plurality of protruding portions that are designed so as not to be detached in the center direction of the sheet-like member. In the joint portion formed by fitting the sheet-like member, no detachment occurs in the center direction of the sheet-like member. For this reason, the endless belt of this invention is excellent in the intensity | strength, durability, etc. of this junction part.

  The endless belt is bonded such that the joining portion is covered with an adhesive member containing the same resin and fibrous filler as the sheet-like member, for example, a film-like adhesive. However, at this time, the fitting portion does not completely lose its shape, and therefore the sheet-like member does not detach in the center direction. Here, the “same thermoplastic resin” means that the constituent monomers are the same chemical species and have different compositions or different polymerization forms within the same range.

  Further, as shown in FIG. 6, the adhesive member 12 may be an adhesive film. The adhesive film contains the same thermoplastic resin and fiber-shaped filler as the fiber-shaped filler sheet-like member, and matches or closes the mechanical properties before bonding to the sheet-like member. It is easy. In addition, by using the adhesive film, the joint portion can be formed in a state where the fibrous filler is uniformly dispersed in the resin. Therefore, it is possible to form a joint portion having high mechanical characteristics equivalent to that of the sheet-like member by joining with the adhesive film having performance equivalent to that of the sheet-like member.

  Below, the raw material of the sheet-like member and adhesive member of this Embodiment is demonstrated concretely. In addition, since the material which comprises both is common, it shall be demonstrated collectively below.

  As the thermoplastic resin, from the viewpoint of mechanical properties, examples of crystalline resins include polyamide, polyethylene terephthalate, polybutylene terephthalate, syndiotactic polystyrene, polyacetal, polyphenylene sulfide, polyether ketone, polyether nitrile, and the like. Among the non-crystalline resins, polycarbonate, polysulfone, polyethersulfone, polyetherimide, polyamideimide, thermoplastic polyimide and the like are desirable, and thermoplastic polyimide and polyamideimide are particularly desirable.

  The fiber-shaped filler according to the present invention has an important shape, and is preferably a fiber shape having an aspect ratio of 10 or more. For example, when the filler has a spherical shape, the belt cannot be provided with bending resistance that can withstand bending stress acting on the small-diameter roller portion. Moreover, when the shape of a filler is plate shape, it aggregates partially and there exists a possibility of reducing the flexibility of the part.

The fibrous filler preferably has a volume resistivity of 10 ⁷ or more from the viewpoint of resistance control of the endless belt. When a conductive filler is added, the resistance varies greatly with the addition amount, and it is difficult to achieve both resistance control in the semiconductive region required for the transfer belt and improvement of mechanical characteristics.

The volume resistivity of the fiber-shaped filler is, for example, a sample obtained by compressing 7 g of fiber-shaped filler at a pressure of 100 kgf / cm ² and using a powder resistance measurement system “MCP-PD51 type” (Dyne Inc.). Measured using the instrument.

  For the above reasons, preferred fillers in the form of fibers in the present invention include, for example, titanium oxide whisker, aluminum borate whisker, potassium titanate whisker, calcium silicate whisker, and basic magnesium sulfate whisker as long as they are inorganic. Etc. Examples of organic substances include nylon fibers, polyester fibers, and aramid fibers. The fibrous filler preferably contains 90% by mass or more of these components. Two or more kinds of fiber-shaped fillers may be mixed, and the plate-like filler may be mixed in an addition amount that does not aggregate. The fiber-shaped filler preferably has an average particle size of 0.01 μm to 3 μm and an average fiber length of 0.2 to 15 μm, an average particle size of 0.01 to 1 μm and an average fiber length of 0.2 to It is particularly desirable to be 5 μm.

  The amount of the fiber-shaped filler added to the resin component is desirably 5 to 60 parts by mass, and particularly preferably 15 to 40 parts by mass with respect to 100 parts by mass of the base resin. If the amount added is too small, sufficient flexibility and strength may not be obtained. On the other hand, if the amount added is too large, the toughness of the resin is lowered, so neither is preferable.

Further, a conductive material is added to the mixture of the thermoplastic resin and the fiber-shaped filler in order to control the resistance value of the belt. As the conductive material, for example, an electron conductive conductive agent, a metal or an alloy such as carbon black, carbon nanotube, graphite, aluminum, nickel, copper alloy, tin oxide, zinc oxide, titanium oxide (TiO), tin oxide-oxide Examples thereof include indium composite oxide. Examples of other electron conductive conductive agents include polyaniline, polypyrrole, polyacetylene, polythiophene, polyisothianaphthene, and polyethylenedioxythiophene as conductive polymers. Examples of the ion conductive conductive agent include Group 1 metal salts such as LiCl, LiCF ₂ SO ₄ , NaClO ₄ , LiBF ₄ , NaCl, and various surfactants such as cationic, anionic, and nonionic surfactants. Two or more kinds of these conductive agents may be mixed. As for said electrically conductive agent, it is especially desirable that the surface is oxidized and adjusted to pH 5.0 or less. When the pH is 5.0 or less, the dispersibility in the binder resin is improved by the effect of the oxygen-containing functional group attached to the surface, and the resistance variation of the intermediate transfer member can be reduced. Examples of such a conductive agent include acidic carbon black that has been subjected to an oxidation treatment and has been given a carboxyl group, a quinone group, a lactone group, a hydroxyl group, or the like on the surface.

  Although there is no restriction | limiting in particular in the addition amount to the resin component of the said electrically-conductive material, For example, in the case of carbon black, it is preferable that it is 5-60 mass parts with respect to 100 mass parts of base resin as organic substance, Organic powder In this case, it is desirable to be in the range of 1 to 50 parts by mass. If the addition amount is too large or too small, the object of controlling the resistance value cannot be sufficiently achieved.

  The addition amount of the fiber-shaped filler and the conductive material to the base resin is preferably the above-mentioned addition amount as a simple substance, but if the total addition amount of the conductive material and the fiber-shaped filler is too large, Thus, the toughness of the resin is lowered. Therefore, it is desirable that the total addition amount of the conductive filler and the fibrous filler is 60 parts by mass or less with respect to 100 parts by mass of the base resin. Furthermore, the amount of the fiber-shaped filler with respect to the total of the resin and the conductive filler is desirably 5 parts by mass or more. If the relative amount of the fibrous filler is too small, sufficient strength and bending resistance cannot be obtained.

  The fiber-shaped filler and conductive agent are dispersed in the thermoplastic resin component by mixing with a roll mill, pressure kneader, Banbury mixer, extruder, etc. that disperses under high shear force, and then a twin screw extruder. Mix and pelletize using a melt kneader. The pellets thus obtained can be formed into a molded product having a desired shape, such as a sheet shape or a film shape, by a commonly used method of molding a thermoplastic resin, such as injection molding, compression molding, extrusion molding or the like. In the present invention, as a molding method, it is desirable to perform extrusion molding using a T die or the like from the viewpoint of dimensional stability.

  In addition, in the process of dispersing the fiber-shaped filler and conductive agent in the thermoplastic resin component, in order to improve processability, stability, etc., a known lubricant, plasticizer, dispersant, surfactant, etc. are used in combination. Also good. Other components may be added during mixing or after dispersion. Examples of such components include known ones such as lubricants, plasticizers, dispersants, surfactants, organic pigments, inorganic pigments, foaming agents, antioxidants, antistatic agents, crosslinking agents, and antifoaming agents. it can.

  The thickness of the endless belt of the present invention is preferably 50 to 200 μm from the viewpoint of maintaining a suitable resistance value and securing sufficient strength and toughness in consideration of its use. It is especially preferable that it is 50-120 micrometers.

  As shown in FIG. 6, the adhesive film as the adhesive member 12 is heat-welded so as to cover the joint portion 11 of the sheet-like member (base material) from above. A method for heat-welding by heating is not particularly limited, and for example, a heating / pressurizing method, an ultrasonic heating method, a high-frequency induction heating method, or the like can be used. The heating method is preferably a method that can heat only the portion to be heat-sealed. When a crystalline resin is used, the heating temperature does not adhere below the glass transition temperature Tg, and when heated to the melting point Tm, the viscosity of the resin becomes too low and the moldability is insufficient. It is desirable to be.

The shape of the adhesive member needs to be very thin so that the bonded portion after bonding does not form a step with the peripheral portion, and the thickness is preferably 10 μm or less, and particularly preferably 5 μm or less. In addition, a gap of about 25 μm is substantially present in the joint portion of the sheet-like member (base material). For example, the volume of the adhesive member 12 shown in FIG. 6 is the gap of the joint portion 11 of the sheet-like member. It is necessary to adjust so that it does not differ greatly from the volume. When it is smaller than the volume of the gap, the film thickness of the joint portion becomes thinner than the peripheral portion. On the other hand, when it is larger than the volume of the gap, the film thickness of the joint becomes thick. When the volume V ₁ of the gap is assumed by the following formula (1), the ratio of the volume of the film to V ₁ is preferably 1 to 2, and particularly preferably 1 to 1.5.
[Formula 1]
V ₁ = (Gap distance in rotation direction = 25 μm) × (sheet width) × (sheet thickness) × 2 (contact length of fitting portion / sheet width)

  In order to obtain a high image, the endless belt of the present invention preferably has a common logarithmic value of surface resistivity of 8.0 to 14.0 (logΩ / □), and 10.0 to 12.0 (logΩ / □) is particularly desirable. Assuming that the common logarithm of the surface resistivity is in the range of 10.0 to 12.0 (log Ω / □), when used as an intermediate transfer belt or transfer conveyance belt in an image forming apparatus described later, toner splatters. In addition, high image quality can be obtained, and contamination due to charge-up can be prevented without a static eliminator.

  When the common logarithmic value of the surface resistivity is less than 8.0 (log Ω / □), an electrostatic force that holds the electrified toner image transferred from the image carrier to the intermediate transfer member works. Therefore, the electrostatic repulsive force between the toners or the fringe electric field near the image edge may cause the toner to scatter around the image (blur) and form a noisy image. On the other hand, when the common logarithmic value of the surface resistivity is higher than 12.0 (logΩ / □), the surface of the intermediate transfer member is charged by the transfer electric field in the primary transfer because the electrification holding power is large. A static elimination mechanism is required.

  In order to obtain a high image, the range of volume resistivity is also important, and the common logarithm of volume resistivity is preferably 8.0 to 14.0 (log Ω · cm), and 8.0 to 13 0.0 (log Ω · cm) is particularly desirable.

  When the common logarithmic value of the volume resistivity is less than 8.0 (log Ω · cm), in the tandem type image forming apparatus described later, since the resistance between each color is low at the time of primary transfer, transfer required in the transfer unit The voltage may not be applied. Further, when the common logarithmic value of the volume resistivity exceeds 13.0 (log Ω · cm), there may be a problem that the charge cannot be sufficiently removed.

(Volume resistivity and surface resistivity)
Here, the volume resistivity and the surface resistivity can be measured according to JIS K 6911 (1995) using a circular electrode (for example, Hiresta UPMCP-450 UR probe manufactured by Dia Instruments Co., Ltd.). The resistivity measurement method will be described with reference to the drawings, which are composed of a schematic plan view of Fig. 7 (a) showing an example of a circular electrode and a schematic cross-section of Fig. 7 (b). Comprises a first voltage application electrode A and a second voltage application electrode B. The first voltage application electrode A has a cylindrical electrode part C and an inner diameter larger than the outer diameter of the cylindrical electrode part C. And a cylindrical ring-shaped electrode portion D surrounding the columnar electrode portion C at regular intervals, the columnar electrode portion C and the ring-shaped electrode portion D in the first voltage application electrode A and the second voltage application electrode B. The semiconductive belt 1 is sandwiched between The current I (A) that flows when the voltage V (V) is applied between the cylindrical electrode portion C and the second voltage application electrode B in the first voltage application electrode A is measured. The volume resistivity ρv (Ωcm) of the member and the film-like adhesive portion can be calculated, where t represents the thickness of the semiconductive belt 1 in the following formula.
Formula 2: ρv = 19.6 × (V / I) × t

Further, the surface resistivity of the intermediate transfer member of the present invention can also be measured according to JIS K 6911 (1995) using a circular electrode (for example, HR probe of Hiresta IP manufactured by Dia Instruments). As the circular electrode used here, the same one as shown in FIG. 7 can be used. The surface resistivity is measured in a state where the intermediate transfer body 1 is sandwiched between the cylindrical electrode portion C and the ring electrode portion D of the first voltage application electrode A and the plate-like insulator B. The current I (A) that flows when the voltage V (V) is applied between the cylindrical electrode portion C and the ring-shaped electrode portion D in the application electrode A is measured, and the intermediate transfer body 1 is expressed by the following equation (4). The surface resistivity ρs (Ω / □) can be calculated. When measuring the surface resistivity of the outer peripheral surface (or inner peripheral surface) of the intermediate transfer member, the intermediate transfer member is arranged so that the outer peripheral surface (or inner peripheral surface) is in contact with the cylindrical electrode portion C and the ring-shaped electrode portion D. The transfer body 1 is disposed.
Formula 3: ρs = π × (D ′ + d) / (D′−d) × (V / I)
Here, in said formula (4), d (mm) shows the outer diameter of the cylindrical electrode part C, D '(mm) shows the inner diameter of the ring-shaped electrode part D. In addition, the measuring method of the said volume resistivity and surface resistivity is applicable also when measuring the volume resistivity and surface resistivity of the base material mentioned above.

  The sheet-like member and the adhesive member can control the common logarithm values of the surface resistivity and the volume resistivity within the above ranges by changing the addition amount of the conductive material. In order to obtain image quality free from defects at the joint, it is necessary to control the surface resistivity and volume resistivity of the joint within the above ranges.

  Therefore, it is extremely important for the adhesive member that the surface resistivity and volume resistivity during molding are close to the surface resistivity and volume resistivity of the sheet-like member, respectively. The difference in surface resistivity between the adhesive member and the sheet-like member is preferably 0 to 1 and particularly preferably 0 to 0.5 as a common logarithmic value. Moreover, it is desirable that the difference in volume resistivity is 0 to 2 as a common logarithmic value. If the difference in surface resistivity between the adhesive member and the sheet-like member is within the above range, the mixing ratio of the conductive material to the resin when producing the adhesive member is not particularly specified.

(Flexibility)
The bending resistance in the present invention was evaluated by the number of foldings by the MIT test method. The folding endurance measurement by the MIT test method is based on JIS P8115 (2001) (“paper and paperboard” in JIS P8115 (2001) is replaced with “polyimide film”). Measured using the MIT test machine shown in FIG. FIG. 5 is a schematic configuration diagram for explaining the MIT testing machine. The MIT testing machine shown in FIG. 5 has a bending device 6 attached to the bending device mounting surface 4 and having a radius of curvature of 0.38 mm for sandwiching the test piece 9 and a load attached to the plunger 8. It consists of a gripping tool 10 for hanging. The procedure for measuring the folding endurance by the MIT test method is as follows. One of the test pieces 9 is sandwiched by the bending device 6. Further, the other one of the test pieces 9 is sandwiched by the gripping tool 10 and a load of 9.8 N (1 kgf) is applied to the test piece 9. Next, the bending device 6 is rotated at an angle of 135 ± 2 ° at a speed of 175 ± 10 times per minute, and the loaded test piece 2 is repeatedly bent on the curvature surface of the bending device 6 to obtain stress. To break.

The bending strength FE is obtained according to the following formula (4) from the number of times of folding N until breakage.
FE = log ₁₀ N (4)
Further, the folding endurance number FN is obtained according to the following formula (5).
FN = 10 ^FE Formula (5)

<Image forming apparatus>
The image forming apparatus of the present invention is not particularly limited as long as it is an intermediate transfer body type image forming apparatus. For example, a normal monocolor image forming apparatus that contains only a single color toner in a developing device, or a color image in which a toner image carried on an image carrier such as a photosensitive drum is subjected to primary transfer sequentially to an intermediate transfer member Any of a forming apparatus, a tandem color image forming apparatus in which a plurality of image carriers having developing units for respective colors are arranged in series on an intermediate transfer member may be used.

  As an example, an embodiment of the present invention using an endless belt of the present invention as an intermediate transfer belt will be described in detail below with reference to the accompanying drawings.

  FIG. 8 is a schematic configuration diagram illustrating a color image forming apparatus 100 to which the exemplary embodiment is applied. A color image forming apparatus 100 shown in FIG. 8 includes four toner cartridges 31, a pair of fixing rolls 32, a backup roll 13, a tension roll 14, a secondary transfer roll (secondary transfer means) 15, a paper path 16, and a paper tray. 17, laser generator 18, four photoconductors (image carrier) 19, four primary transfer rolls (primary transfer means) 20, drive roll 21, transfer cleaner 22, four charging rolls 23, and photoconductor cleaner 24. The developing unit 25, the intermediate transfer belt 26, and the like are included as main constituent members. In the color image forming apparatus 100 shown in FIG. 8, the endless belt in the present embodiment is used as an intermediate transfer belt 26 that functions as a toner image superimposing unit and a toner image transferring unit.

  Next, the configuration of the color image forming apparatus 100 shown in FIG. 8 will be sequentially described. First, around the photosensitive member 19, a charging roller 23, a developing device 25, a primary transfer roller 20 and a photosensitive member cleaner 24 arranged via an intermediate transfer belt 26 are arranged counterclockwise. The member forms a developing unit corresponding to one color. Each developing unit is provided with a toner cartridge 31 for replenishing the developer in the developing unit 25. The photosensitive member 19 of each developing unit is exposed to a photosensitive member between the charging roll 23 and the developing unit 25. A laser generator 18 capable of irradiating the surface of the body 19 with laser light corresponding to image information is provided.

  Four developing units corresponding to four colors (for example, cyan, magenta, yellow, and black) are arranged in series in a substantially horizontal direction in the image forming apparatus. An intermediate transfer belt 26 is provided so as to pass through the nip portion with the transfer roll 20. The intermediate transfer belt 26 is stretched by a backup roll 13, a tension roll 14, and a drive roll 21 provided on the inner peripheral side thereof in the following order in the counterclockwise direction. The four primary transfer rolls are located between the tension roll 14 and the drive roll 21. A transfer cleaner 22 for cleaning the outer peripheral surface of the intermediate transfer belt 26 is provided on the opposite side of the drive roll 21 via the intermediate transfer belt 26 so as to be in pressure contact with the drive roll 21.

  Further, a toner image formed on the outer peripheral surface of the intermediate transfer belt 26 on the surface of the recording paper conveyed from the paper tray 17 via the paper path 16 to the opposite side of the backup roll 13 via the intermediate transfer belt 26. A secondary transfer roll 15 for transferring the ink is provided so as to be in pressure contact with the backup roll 13. On the outer peripheral surface of the intermediate transfer belt 26 between the backup roll 13 and the drive roll 21, a neutralizing roll (not shown) is provided for neutralizing the outer peripheral surface.

  Further, a paper tray 17 for stocking recording paper is provided at the bottom of the color image forming apparatus 100, and a backup roll 13 and a secondary transfer roll 15 that constitute a secondary transfer unit from the paper tray 17 via a paper path 16. It can supply so that it may pass through the press-contact part. The recording sheet that has passed through the press contact portion can be further transported by transport means (not shown) so as to be inserted through the press contact portions of the pair of fixing rolls 32, and finally discharged out of the color image forming apparatus 100. it can.

  Next, an image forming method using the color image forming apparatus 100 of FIG. 8 will be described. The toner image is formed for each developing unit. After uniformly charging the surface of the photoconductor 19 rotating counterclockwise by the charging roll 23, the photoconductor 19 charged by the laser generator 18 (exposure device) is used. A latent image is formed on the surface, and then this latent image is developed with the developer supplied from the developing unit 25 to form a toner image, which is conveyed to the pressure contact portion between the primary transfer roll 20 and the photoreceptor 19. The transferred toner image is transferred to the outer peripheral surface of the intermediate transfer belt 26 rotating in the arrow X direction. The photosensitive member 19 after transferring the toner image is cleaned with toner or dust attached to the surface thereof by the photosensitive member cleaner 24 to prepare for the formation of the next toner image.

  The toner images developed for each color development unit are sequentially superimposed on the outer peripheral surface of the intermediate transfer member 26 so as to correspond to the image information, and are conveyed to the secondary transfer unit by the secondary transfer roll 15. The image is transferred from the paper tray 17 to the surface of the recording paper conveyed via the paper path 16. The recording paper on which the toner image has been transferred is further fixed by being heated by pressure when passing through the pressure contact portion of a pair of fixing rolls 32 constituting the fixing portion, and after the image is formed on the surface of the recording medium. Then, it is discharged out of the color image forming apparatus 100.

  The intermediate transfer belt that has passed through the secondary transfer portion further proceeds in the direction of the arrow X, and after the outer peripheral surface is neutralized by a neutralizing roll (not shown), the outer peripheral surface is further cleaned by the transfer cleaner 22, and the next toner image Prepare for transcription.

  As the photoreceptor 19 (image carrier), a conventionally known one can be used, and as the photosensitive layer, a known one such as organic or amorphous silicon can be used. Are preferred. When the image carrier is cylindrical, it can be obtained by a known manufacturing method such as surface processing after extrusion molding of aluminum or an aluminum alloy. It is also possible to use the belt-shaped image carrier.

  The charging roll 23 (charging means) is not particularly limited. For example, a contact-type charger using a conductive or semiconductive roller, brush, film, rubber blade, etc., a scorotron charger using corona discharge, Known chargers such as a corotron charger can be used. Among these, a contact-type charger is preferable in terms of excellent charge compensation capability. The charging unit normally applies a direct current to the electrophotographic photosensitive member, but an alternating current may be applied in a superimposed manner.

  The laser generator 18 (exposure means) is not particularly limited. For example, a light source such as semiconductor laser light, LED light, or liquid crystal shutter light, or a desired light source from these light sources via a polygon mirror is provided on the surface of the photosensitive member 19. And optical system equipment that can be exposed like the above image.

  The developing device 25 (developing means) can be appropriately selected according to the purpose. For example, the developing device 25 is developed by bringing a one-component developer or a two-component developer into contact or non-contact with each other using a brush, a roller, or the like. A well-known developing device etc. are mentioned.

  As the primary transfer roll 20 (first transfer means), for example, a contact transfer charger using a belt, a roller, a film, a rubber blade or the like, a scorotron transfer charger using corona discharge, a corotron transfer charger, etc. A transfer charger known per se can be used. Among these, a contact type transfer charger is preferable in that it has excellent transfer charge compensation capability. In the present invention, in addition to the transfer charger, a peeling charger can be used in combination.

  Examples of the secondary transfer roll 15 (second transfer unit) include a contact transfer charger, a scorotron transfer charger, and a corotron transfer charger. Among these, a contact-type transfer charger is preferable like the first transfer unit. If the contact-type transfer charger such as a transfer roll is pressed strongly, the image transfer state can be maintained in a good state. Also, when a contact type transfer charger such as a transfer roller is pressed at the position of the roller that guides the intermediate transfer belt 16, the toner image is transferred from the intermediate transfer belt 16 to the transfer target (paper) in a good state. It becomes possible to do in.

  The fixing roll 32 (fixing means) is not particularly limited, and examples thereof include a fixing device known per se, such as a heat roller fixing device and an oven fixing device.

  The cleaning means is not particularly limited, and a known cleaning device or the like may be used.

  Furthermore, it is also preferable to install a light neutralizing means. Examples of the light neutralizing means include tungsten lamps and LEDs. Examples of the light quality used in the light neutralizing process include white light such as tungsten lamps and red light such as LED light. The irradiation light intensity in the photostatic process is usually set to output several times to about 30 times the amount of light indicating the half exposure sensitivity of the electrophotographic photosensitive member.

[Preferred embodiment]
<1> Contains a fiber-shaped filler and a thermoplastic resin, and has a joint portion formed by joining both ends of a sheet-like member molded into a sheet shape, and each end portion is in mesh with each other. An adhesive member having elements, wherein the meshing elements are fitted to each other to prevent separation of both end portions, and the joint portion of the end portions contains the same resin and the same fibrous filler as the sheet-like member Endless belt joined by
<2> A method for producing an endless seamless belt comprising a fiber-shaped filler and a thermoplastic resin, and having a joint formed by joining both ends of a sheet-like member molded into a sheet shape, Each end portion has a plurality of mutual meshing elements, and the meshing elements are mutually fitted to prevent separation of both end portions, and the joint portion of the end portions is the same thermoplastic resin as the sheet-like member And a step of joining with an adhesive member made of the same fiber-shaped filler.
<3> The belt according to <1>, wherein a step difference in the joint portion is 5 μm or less.
<4> The endless belt according to <1>, wherein the adhesive member according to <1> is in a film form.
<5> The endless belt according to <1>, wherein the volume ratio of the adhesive member according to <1> with respect to the volume of the gap between the joints is 0.8 to 1.5.
<6> The endless belt according to <1>, wherein the fiber-shaped filler according to <1> has a volume resistivity of 10 ⁸ to 10 ¹⁴ Ω · cm.
<7> An electrophotographic apparatus equipped with the endless belt according to any one of <1> and <3> to <6>.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
1-1. Synthesis of thermoplastic polyimide:
15000 g of N-methyl-2-pyrrolidone (NMP) was placed in a 5000 ml flask equipped with a stirring blade and heated to 60 ° C. As a diamine compound, 160.03 g of 4,4′-diaminodiphenyl ether was added and stirred until it was completely dissolved. While continuing heating and stirring, as the specific tetracarboxylic dianhydride, 4- (2,5-dioxotetrahydrofuran-3-yl) -1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic acid 239.97 g of anhydride was gradually added and dissolved. After the tetracarboxylic dianhydride was dissolved, the polyamic acid polymerization reaction proceeded and the viscosity of the solution increased. When the viscosity of the solution reached 10 Pa · s, 2000 g of NMP was added and diluted to 10%, and then cooled to room temperature to obtain a polyamic acid (1-0) solution.

  500 g of the polyamic acid (1-0) solution obtained as described above was weighed into a flask container, and 31.60 g of pyridine and 40.35 g of acetic anhydride were added. Dehydration ring closure reaction was performed at 120 ° C. for 3 hours. After distilling off the catalyst and the dehydrating agent, the solution concentration was adjusted to 10% to obtain a polyimide (1-1) solution. A part of the polyimide (1-1) was poured into methyl alcohol to precipitate the produced polymer. Washed with methanol, dried at 40 ° C. under reduced pressure for 15 hours, dissolved in d6-DMSO (N, N-dimethylsulfoxide), quantified carboxylic acid protons attributed to amic acid by NMR, and determined imidation rate. The calculated value was 100%.

1-2. Production of sheet-like member:
100 parts by mass of polyimide obtained as described above, 20 parts by mass of carbon black 3030B (manufactured by Mitsubishi Chemical Corporation) and fibrous titanium oxide (FTL-100, average particle size 0.15 μm, average fiber length 1.68 μm, A composition in which 25 parts by mass of a volume resistance of 1.0 × 10 ¹³ (Ω · cm), manufactured by Ishihara Sangyo Co., Ltd. was mixed was prepared. This composition was kneaded with a twin-screw kneader to give pellets, and the pellets were made into long resin sheets using a 40 mm single screw extruder and a 365-mm wide T-die. The temperature conditions of the extruder were set such that the resin supply part temperature was 370 ° C., the compression part inlet temperature was 390 ° C., the compression part outlet temperature was 400 ° C., and the temperature of the metering part, adapter, and T die were 390 ° C. The screw rotation speed was 60 rotations / minute, and the sheet was cooled to a predetermined temperature while adjusting the take-up speed so that the sheet thickness after take-up was 80 μm, to obtain a long resin sheet. A 10 cm × 10 cm test piece was cut out from the obtained sheet, and the surface resistivity was measured in an Lab environment (humidity 40%, temperature 22 ± 3 ° C.) with an ultra-high resistance measuring device manufactured by Advantest. The average logarithmic value was 10.8 (log Ω / □), and the average logarithmic value of volume resistivity was 9.5 (log Ω · cm). Using the sheet-like polyimide resin having a thickness of about 80 μm obtained as described above as a base material, both ends of this sheet were mechanically cut using a die cutter, and a plurality of pieces as shown in FIG. A puzzle cut pattern was formed by the substantially circular protruding portion 2a and a plurality of base portions 2b having a narrower width. The puzzle cut patterns formed at both ends of the sheet can be fitted to each other. Let this puzzle cut pattern be a fitting part.

1-3. Production of adhesive members:
Polyimide, carbon black 3030B (manufactured by Mitsubishi Chemical Corporation), fibrous titanium oxide (FTL-100, average particle diameter 0.15 μm, average fiber length 1.68 μm, volume resistance at the same mixing ratio as (1-2) above A composition in which 1.0 × 10 ¹³ (Ω · cm), manufactured by Ishihara Sangyo Co., Ltd.) was mixed was extruded in the same manner as in the above (1-2). At this time, an adhesive film was obtained by cooling to a predetermined temperature while adjusting the take-up speed so that the thickness of the film after taking was 5 μm.

  When a 10 cm × 10 cm test piece was cut out from the obtained resin film and the surface resistivity was measured in an Lab environment using an ultra-high resistance measuring device manufactured by Advantest, the average logarithmic value of the surface resistivity was 10.8. (Log Ω / □), the average value of the volume resistivity was 9.5 (log Ω · cm). This resin film was cut into a predetermined size by NT Co., Ltd. NT cutter.

1-4. Production of endless belt:
Next, both ends of the sheet were meshed with each other so that the sheet was not twisted, and the whole was formed into an endless belt. And after arrange | positioning the joint part of this endless belt on the lower heat plate of a cantilever type hot press machine, as shown in FIG. 6, the film 12 for adhesion obtained by the method described above in (1-2) above. Was arranged so as to cover the joint 11 from above. In order to join the thermoplastic polyimide material onto the joint, it was heated at about 380 ° C. for about 60 seconds with light pressure. Thereafter, it was further heated at about 390 ° C. for about 10 minutes while being pressurized at a pressure of about 2.5 kgf / cm ² . The step difference between the joined portion and the non-joined portion of the endless belt obtained as described above was 5 μm or less at the maximum. The peripheral length of the endless belt was 527.8 mm.

(Example 2)
An endless belt was produced in the same manner as in Example 1 except that the mixing ratio of the powder at the time of producing the sheet-like member and the adhesive member was 100 parts by mass of polyimide, 20 parts by mass of carbon black, and 35 parts by mass of titanium oxide.

(Example 3)
Implemented except using fibrous potassium titanate filler (Tismo-D, average particle size 0.5 μm, average fiber length 15 μm volume resistivity 10 ¹⁴ (Ω · cm), manufactured by Otsuka Chemical) instead of titanium oxide whisker. An endless belt was produced in the same manner as in Example 1.

(Example 4):
Similar to Example 1, a sheet-like member was produced based on the description in (1-2) above. On the other hand, the adhesive member was produced based on the following (2-3).

2-3. Production of adhesive members:
100 parts by mass of the polyimide obtained in (1-1) above, 20 parts by mass of carbon black 3030B (manufactured by Mitsubishi Chemical Corporation), and fibrous titanium oxide (FTL-100, average particle size 0.15 μm, average fiber length 1. Extrusion molding was carried out in the same manner as in the above (1-2) except that a composition in which 15 parts by mass of 68 μm, volume resistance 1.0 × 10 ¹³ (Ω · cm), manufactured by Ishihara Sangyo Co., Ltd.) was mixed was prepared. At this time, an adhesive film was obtained by cooling to a predetermined temperature while adjusting the take-up speed so that the thickness of the film after taking was 5 μm.

  When a 10 cm × 10 cm test piece was cut out from the obtained resin film and the surface resistivity was measured in an Lab environment using an ultra-high resistance measuring device manufactured by Advantest, the average logarithmic value of the surface resistivity was 10.5. (Log Ω / □), the average value of the resistance value of the volume resistivity was 9.3 (log Ω · cm). This resin film was cut into a predetermined size with NT Co., Ltd. NT cutter.

(Example 5):
Similar to Example 1, a sheet-like member was produced based on the description in (1-2) above. On the other hand, the adhesive member was produced based on the following (3-3).

3-3. Production of adhesive members:
100 parts by mass of the polyimide obtained in (1-1) above, 20 parts by mass of carbon black 3030B (manufactured by Mitsubishi Chemical Corporation), and fibrous titanium oxide (FTL-100, average particle size 0.15 μm, average fiber length 1. Extrusion molding was carried out in the same manner as in the above (1-2) except that a composition in which 35 parts by mass of 68 μm, volume resistance 1.0 × 10 ¹³ (Ω · cm), manufactured by Ishihara Sangyo Co., Ltd.) was mixed was prepared. At this time, an adhesive film was obtained by cooling to a predetermined temperature while adjusting the take-up speed so that the thickness of the film after taking was 5 μm.

  When a 10 cm × 10 cm test piece was cut out from the obtained resin film and the surface resistivity was measured in a Lab environment using an ultra-high resistance measuring device manufactured by Advantest, the average logarithmic value of the surface resistivity was 11.1. (Log Ω / □), the average value of the volume resistivity was 9.7 (log Ω · cm). This resin film was cut into a predetermined size with NT Co., Ltd. NT cutter.

(Comparative Example 1)
Fabrication of belts that are overlapped and welded:
A long polyimide resin sheet having a thickness of 80 μm that was extruded in the same manner as in Example 1 was cut to a length of 557.8 mm. The overlapped portion was pressurized and heat-welded in the same manner as in Example 1 in a state where both ends were stacked over a length of 30 mm on a jig having a step of 50 μm. The step difference at the joining portion of the endless belt thus obtained was 45 μm. After the joint was shaved with # 200 sandpaper, the step difference between the joint and the non-joint was a maximum of 10 μm.

(Comparative Example 2)
Fabrication of a belt with a film containing no filler:
A composition was prepared by mixing 100 parts by mass of polyimide obtained by the same synthesis method as in (1-1) above and 20 parts by mass of carbon black 3030B. This composition was kneaded with a twin-screw kneader to give pellets, and the pellets were made into long resin sheets using a 40 mm single screw extruder and a 365-mm wide T-die. The temperature conditions of the extruder were set such that the resin supply part temperature was 370 ° C., the compression part inlet temperature was 390 ° C., the compression part outlet temperature was 400 ° C., and the temperature of the metering part, adapter, and T die were 390 ° C. The resin was obtained by cooling to a predetermined temperature while adjusting the take-up speed so that the screw rotation speed was 60 rpm and the sheet thickness after take-up was 5 μm. This resin film was cut into a predetermined size with NT Co., Ltd. NT cutter. An endless belt was produced in which the seam of the polyimide sheet molded in the same manner as in Example 1 was joined with a film containing no fibrous filler obtained by the method described above. The step difference between the joined portion and the non-joined portion of the endless belt thus obtained was 5 μm at maximum and the circumference was 527.8 mm.

(Comparative Example 3)
Belt containing plate filler:
A sheet-like member using a plate-like filler (mica, volume resistance 5 × 10 ¹³ (Ω · cm), manufactured by Yamaguchi Mika Kogyo Co., Ltd.) having an average particle size of about 5.2 μm instead of the fiber-shaped filler An endless belt was produced in the same manner as in Example 1 except that the adhesive member was produced.

(Comparative Example 4)
Fabrication of a belt joined with a base material and a different film adhesive:
The sheet-like member obtained in the same manner as in Example 1 was meshed with both ends of the sheet-like member to form an endless belt, and then an uncured film made of a thermosetting epoxy material (manufactured by ThreeBond Co., Ltd., TB1650) was used. It arrange | positioned so that it might cover from the upper part of a fitting part. In order to join the thermosetting epoxy material onto the joint, it was heated at about 120 ° C. for about 60 seconds under light pressure. Thereafter, the release paper was removed and further heated at about 180 ° C. for about 10 minutes while being pressurized at a pressure of about 2.5 kgf / cm ² . As described above, the adhesive member made of the thermosetting epoxy material was cured, and a cured film made of the thermosetting epoxy material was formed on the joint.

(Comparative Example 5)
Production of a belt containing a conductive fiber-shaped filler:
100 parts by mass of polyimide resin and carbon fiber (VGCF (registered trademark), average particle size 0.15 μm, average fiber length 15 μm, volume resistance 1.2 × 10 ⁻² (Ω · cm) (powder) manufactured by Showa Denko) 35 parts by mass were mixed to obtain a polyimide resin sheet-like member and an adhesive film in the same manner as in Example 1 to produce an endless belt.

[Evaluation results]
The evaluation results of Examples 1 to 5 and Comparative Examples 1 to 5 are shown in Table 3.

[Folding resistance evaluation]
The number of folding times was measured according to JIS P8115 (2001), using a MIT testing machine shown in FIG. 5 with a sample piece width of 11 mm and a tension of 9.8 N (1 kgf), and the number of folding times was determined. The test was performed 5 times in an environment of 55% humidity and a temperature of 22.5 ± 2 ° C., and the average value was taken as the measured value. Here, the number of folding times refers to the number of times of bending until breakage when a test piece is produced in the circumferential direction of the belt and a load is applied in the circumferential direction of the belt. As a result of the measurement, the average folding times of the joints according to Examples 1 to 5 were 403 times, 350 times, 425 times, 380 times, and 360 times, respectively. On the other hand, the folding endurance of the joint part of Comparative Example 1 is 28 to 55 times compared to the sample of the example, except for Comparative Example 5 using a conductive fiber-shaped filler. It became low.

[Evaluation of transfer image quality]
The endless belts obtained in Examples 1 to 3 and Comparative Examples 1 to 5 are mounted as intermediate transfer belts on Docu Color 1255CP manufactured by Fuji Xerox Co., Ltd. shown in FIG. The image quality was evaluated. This evaluation test was performed in a Lab environment having a humidity of 40% and a temperature of 22 ± 3 ° C. The evaluation standard is to print a solid image and a halftone image using A4 size J paper (manufactured by Fuji Xerox Co., Ltd.), judge with the naked eye, and evaluate in the following three stages. Indicated by Δ and ×.
○: No problem in image quality irregularity or image quality defect △: There is a slight image quality irregularity, image quality defect ×: There is an image missing at the joint of the endless belt, and the image quality is clearly poor

  As a result of the evaluation, the print samples of the belts of Examples 1 to 5 were the initial 100 sheets, and no image quality defects were observed. On the other hand, the print sample of the belt of Comparative Example 1 showed a slight density unevenness at the joint, although it was light. In the print sample of the belt of Comparative Example 2, density unevenness was clearly observed in the portion where the adhesive film was welded, as compared with Comparative Example 1. In the print sample of Comparative Example 3, good image quality was obtained up to the 72nd sheet, but it was confirmed that a minute image quality defect occurred in a part of the joint from the 72nd sheet onward. When the belt was checked after the test, a small crack occurred at the position where the image quality defect was caused. In the print sample of Comparative Example 4, an image could not be formed with the sheet-like adhesive portion. In Comparative Example 5, the measured values of the surface resistance and volume resistance of the joint could be controlled within the desired ranges, but slight density unevenness was observed in the local range that could not be detected by the resistance measurement. It was.

  As an application example of the present invention, there is application to an image forming apparatus such as a copying machine or a printer using an electrophotographic system.

It is a figure which shows an example of the shape of the fitting part of the endless belt of this invention. It is a figure which shows the other example of the shape of the fitting part of the endless belt of this invention. It is a figure which shows the other example of the shape of the fitting part of the endless belt of this invention. It is a figure which shows the other example of the shape of the fitting part of the endless belt of this invention. It is a schematic block diagram explaining the structure of the MIT test device for measuring folding resistance. It is a figure explaining adhesion | attachment by the adhesive member of this Embodiment. It is a figure explaining the measuring method of volume resistivity. 1 is a schematic diagram for explaining a main part of a tandem image forming apparatus to which the present invention is applied. FIG.

Explanation of symbols

  2a, 2c, 2d Projection piece, 2b base part, 2e notch part, 8 plunger, 9 test piece, 10 gripping tool, 11 joint part, 12 adhesive film, 13 backup roll, 14 tension roll, 16 paper path, 17 paper Tray, 18 Laser generator, 19 Photoconductor, 20 Primary transfer roll, 21 Drive roll, 22 Transfer cleaner, 23 Charging roll, 24 Photoconductor cleaner, 25 Developer, 26 Intermediate transfer belt, 31 Toner cartridge, 32 Fixing roll , A 1st voltage application electrode, B 2nd voltage application electrode, C Cylindrical electrode part.

Claims (2)

It consists of a sheet-like member containing a thermoplastic resin and a fiber-shaped filler, and two end portions of the sheet-like member have a plurality of fitting portions fitted to each other, and the plurality of fittings Having a joint part joined endlessly by the part,
The endless belt, wherein the joining portion is bonded by an adhesive member containing the same thermoplastic resin as that contained in the sheet-like member and the same fiber-shaped filler. An image carrier;
Charging means for charging the surface of the image carrier;
Latent image forming means for forming a latent image on the surface of the image carrier;
Developing means for developing the latent image with toner to form a toner image;
Transfer means for transferring the toner image onto a recording medium;
Have
The transfer means is composed of a sheet-like member containing a thermoplastic resin and a fiber-shaped filler, and two end portions of the sheet-like member have a plurality of fitting portions fitted to each other, It has a joint part joined endlessly by this plurality of fitting parts, and the joint part contains the same thermoplastic resin and the same fiber-shaped filler that are contained in the sheet-like member An image forming apparatus comprising an endless belt bonded by an adhesive member.

Images