JP2010285478A - Conductive seamless belt and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a conductive seamless belt which is manufactured by an extrusion molding method being a system preferable in cost more than a conventional thermosetting resin belt and rubber layered belt, and has excellent three performances of durability, roller weakness resistance and an elastic modulus. <P>SOLUTION: In the conductive seamless belt formed by irradiating a seamless belt with electron beams, obtained by extrusion molding of a molding material formed by heating and mixing a thermoplastic polymer component consisting essentially of a polyalkylene terephthalate and/or a polyalkylene naphthalate and containing a polyester elastomer and a conductive agent, the seamless belt to be irradiated with the electron beams has 0 to 60°C glass transition temperature and a sum total electron beam amount of 500 to 1,500 kGy is radiated on the condition of 50 to 100 kGy radiation amount per once. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a seamless belt and an image forming apparatus belt such as an intermediate transfer belt, a conveyance transfer belt, and a photosensitive belt, which are used in an electrophotographic copying machine, a laser beam printer, a facsimile machine, and the like using the seamless belt. The present invention relates to a conductive seamless belt useful as an image forming apparatus, and an image forming apparatus including the conductive seamless belt.

  As an image forming method in an image forming apparatus such as an OA device, a toner image formed on the surface of an image carrier made of a photoconductor is primarily transferred to a transfer member before being transferred to a recording medium such as paper, and then There are known an intermediate transfer method for secondary transfer to a recording medium, a paper conveyance method for transferring a recording medium such as paper by a transfer member, and transferring the recording medium to the recording medium. As a transfer member, a conductive belt such as a photoreceptor belt, an intermediate transfer belt, a paper transfer belt, a transfer separation belt, a charging tube, a developing sleeve, a fixing belt, a toner transfer belt, etc. A seamless belt (endless belt) controlled to have various insulating electric resistances is used.

  For example, an intermediate transfer device used in an electrophotographic system is configured to once form a toner image on an intermediate transfer member and then transfer the toner to paper or the like. An endless belt made of a seamless belt is used for charging and discharging the toner on the surface layer of the intermediate transfer member. The seamless belt is set to have different surface electric resistance and thickness direction electric resistance (hereinafter referred to as “volume electric resistance”) for each machine model, and is adjusted to be conductive, semiconductive, or insulative.

  In addition, the paper transport transfer device holds the paper once on the transport transfer body, transfers the toner from the photosensitive member onto the paper held on the transport transfer body, and further removes the paper from the transport transfer body by discharging. It is configured. On the surface of the transport transfer body, an endless belt with or without a seam is used for charging or neutralizing paper. The endless belt is set to have different surface electric resistance and volume electric resistance for each machine model, like the intermediate transfer belt.

  FIG. 1 is a side view of a general intermediate transfer apparatus. In the figure, 1 is a photosensitive drum and 6 is a conductive endless belt. 1 is an electrophotographic process unit including a charging device 2, an exposure optical system 3 using a semiconductor laser as a light source, a developing device 4 containing toner, and a cleaner 5 for removing residual toner. Is arranged. The conductive endless belt 6 is wound around the transport rollers 7, 8, and 9 and moves in the direction of the arrow in synchronization with the photosensitive drum rotating in the direction of the arrow.

  Next, the operation will be described. First, the surface of the photosensitive drum 1 rotating in the direction of arrow A is uniformly charged by the charger 2. Next, an electrostatic latent image corresponding to an image obtained by an image reading device (not shown) is formed on the photosensitive drum 1 by the optical system 3. The electrostatic latent image is developed into a toner image by the developing device 4. This toner image is electrostatically transferred to the conductive endless belt 6 by the electrostatic transfer machine 10 and transferred to the recording paper 11 between the conveying roller 9 and the pressing roller 12.

  By the way, in the case of a conductive endless belt used in an image forming apparatus such as an electrophotographic copying machine or a printer, since it is functionally driven with a high tension and a high voltage for a long time by two or more rolls, sufficient Mechanical and electrical durability is required.

  In particular, in the case of an intermediate transfer belt used in an intermediate transfer device or the like, an image is formed with toner on the belt and transferred to paper, so if the belt is loosened, stretched or meandered during driving, the image Due to misalignment, high dimensional accuracy (small circumferential length difference in belt width and uniform thickness), high elastic modulus (high tensile elastic modulus in belt circumferential direction), high bending resistance The thing excellent in (it is hard to break) is desired.

  In recent years, electrophotographic image forming apparatuses such as color laser printers and color LED printers have become more competitive with low-cost inkjet image forming apparatuses. Therefore, the electrophotographic image forming apparatus aims at differentiating from the inkjet system by a high-speed printing technique, and is an image forming apparatus that prints at a high speed by a tandem type paper conveyance transfer in which four photoconductors are arranged and an intermediate transfer system. Has been commercialized. For this reason, further improvement in durability and prevention of image misalignment have become increasingly important for endless belts for image forming apparatuses.

  Conventionally, endless belts have achieved certain results by improving their materials. However, recently, not only high-speed printing but also the demand for improving image quality has been increasing. Especially, high-quality images can be obtained in a wide range of temperature and humidity environments, and only special paper for color printers. However, it is becoming particularly important for high-quality paper, recycled paper, backing paper, and OHP film to obtain high image quality in order to differentiate from inkjet printers.

  For this reason, development of polymerized toners has progressed, and toners with a small average particle size of 4 to 6 μm and small particle size variations have been commercialized, leading to surface characteristics, chemical characteristics, and electrical characteristics for transfer belts. There is a growing demand for improvement.

  In particular, in the case of a transfer belt used in an intermediate transfer device or the like, the toner on the photoconductor is directly transferred onto the transfer belt by electrostatic force (primary transfer), and after synthesizing a color image on the transfer belt, the toner is added. In order to transfer (secondary transfer) to paper with electrostatic force, not only the electrical resistance characteristics such as the surface electrical resistance and volume electrical resistance characteristics of the transfer belt are important, but also physical surface characteristics and the like need to be improved.

  For example, in color printers and copiers that are becoming increasingly smaller in recent years, the transfer belt and the fixing heat source are close to each other, and the transfer belt is easily stretched by a roller and exposed to the high heat of the fixing heat source. Roller traces remain on the surface, which tends to adversely affect the image. There is a need for a transfer belt in which the roller wrinkles hardly remain, that is, the roller wrinkle restoration rate is high.

  In addition, when the toner remaining on the transfer belt after the secondary transfer is cleaned with a cleaning blade, the transfer belt surface is scraped with silica particles and titanium particles adhering to the toner surface, so that the image is adversely affected. There is a need for a transfer belt with high elasticity and high surface hardness.

Therefore, the following technologies have been proposed to improve the mechanical and thermal properties of seamless belts in order to improve individual folding resistance, roller wrinkle recovery (roller resistance), surface hardness, and elastic modulus. Has been.
(1) A polymer alloy of crystalline thermoplastic resin and amorphous thermoplastic resin (specifically, PBT (polybutylene terephthalate) / PC (polycarbonate) alloy) is used for the seamless belt (Japanese Patent No. 3671840).
(2) Using an elastomer for the seamless belt (Japanese Patent Laid-Open No. 2005-309227)
(3) A polymer having a high glass transition temperature is used for the seamless belt (Japanese Patent Laid-Open No. 2005-266760).
(4) Performing electron beam crosslinking on a seamless belt (Japanese Patent No. 3821600, Japanese Patent Laid-Open No. 2007-65587)

  As described in Japanese Patent No. 3671840, when a polymer alloy of a crystalline thermoplastic resin and an amorphous thermoplastic resin is used for a seamless belt, the ratio of the amorphous part increases as the compatibility increases. Although increased, the roller resistance tends to deteriorate, which is not preferable.

  Also, as disclosed in JP-A-2005-309227, when an elastomer is used for a seamless belt, since the elastomer has a glass transition temperature near room temperature to room temperature or less, the temperature is from room temperature to 60 ° C. where the printer is used. Since it becomes rubbery and soft, it has good folding resistance and roller resistance, but is not preferred because it has a low elastic modulus and is easy to scrape.

Also, as disclosed in JP-A-2005-266760, when a resin having a high crystallinity with a glass transition temperature of 60 ° C. or higher, such as polybutylene naphthalate, is used for the seamless belt, the elastic modulus is high, but the roller resistance The inertia may be good or bad depending on the degree of crystallinity, and the folding resistance is low, which is not preferable. Since a resin having a high glass transition temperature such as polybutylene naphthalate has a high melting point, the polymer is easily oxidized during molding due to a high molding temperature, and the folding resistance is likely to be lowered. In order to improve folding resistance, a resin having a glass transition temperature higher than 60 ° C. such as polybutylene naphthalate is blended with a resin having a glass transition temperature lower than 60 ° C. such as polybutylene terephthalate or elastomer. This method is not preferable because the glass transition temperature of the whole blend is lowered and the folding resistance is increased, but the elastic modulus is deteriorated.
Further, when a resin having a glass transition temperature of 60 ° C. or higher and a low crystallinity such as polyethylene terephthalate or polyethylene naphthalate is used, the elastic modulus is high, but it is not preferable because the roller resistance and folding resistance are poor.

  Further, as in Japanese Patent No. 3821600, when an electron beam cross-linking is carried out at an irradiation dose of 20 to 100 KGy without using a cross-linking agent on an elastomer seamless belt having an aromatic elastomer as a main chain, the cross-linking is difficult to proceed. In many cases, a polymer having an elastic modulus of If the elastomer is the main component, the glass transition temperature before cross-linking is less than 0 ° C., and even if the cross-linking can proceed by adding a cross-linking agent, it is difficult to obtain a polymer having a target elastic modulus. Moreover, even if a polymer having a target elastic modulus is obtained, the change in the degree of crosslinking before and after crosslinking is too large, so that the circumferential shrinkage rate of the polymer increases and the dimensional accuracy deteriorates. Moreover, it is not preferable because the electric resistance value changes due to shrinkage.

  Further, as disclosed in Japanese Patent Application Laid-Open No. 2007-65587, even when electron beam crosslinking is performed on a polymer having a glass transition temperature before crosslinking higher than 60 ° C., a polymer satisfying a target elastic modulus before crosslinking is obtained. Since electron beam crosslinking is performed and the elastic modulus is increased, folding resistance is lowered, which is not preferable. Even if the folding endurance does not decrease, some shrinkage occurs in electron beam cross-linking, which causes a crack in the seamless belt due to the shrinkage, which is not preferable. That is, in JP 2007-65587 A, when irradiating an electron beam to a seamless belt, a metal cylinder is inserted into the belt, and the belt surface is irradiated with an electron beam while rotating the cylinder. However, since the electron beam irradiation of the polymer is accompanied by shrinkage, it is not preferable to insert the seamless belt into the metal cylindrical body and irradiate the electron beam in this manner, because the seamless belt cracks.

  In general, an electron produced by irradiating a compatible resin such as PBT / PC alloy, an aromatic elastomer, a resin having a high glass transition temperature, or a polyester elastomer with an electron beam having an irradiation dose of about 20 to 100 KGy. With wire cross-linking, one or two of durability, roller resistance, and elastic modulus are improved, but it is difficult to provide a seamless belt having three performances. For this reason, the present situation is that it is desired to develop a seamless belt having these three properties of durability, roller resistance, and elastic modulus.

  Conventionally, several proposals have been made for electron beam irradiation on polymers, but polymers having an aromatic ring in the molecule, such as PBT, conjugated electrons at the time of electron beam irradiation with a benzene ring. Therefore, it is said that the electron beam crosslinking is difficult to proceed. For example, in Japanese Patent Application Laid-Open No. 57-212216, a PBT that does not melt in a solder bath when a cross-linking agent is added to PBT and irradiated with an electron beam under conditions of 10, 20, or 30 MRad (equivalent to 100, 200, 300 kGy). Is reported to be obtained. However, for the purpose of the present invention, a recording medium held by electrostatic attraction is circulated by a driving member and conveyed to an image forming body, and each toner image is transferred to the recording medium. In conductive seamless belt applications, even if a crosslinking agent is blended, the desired elastic modulus cannot be obtained under electron beam irradiation conditions of about 100 to 300 kGy. Also, high irradiation conditions of about 1000 kGy are not preferable because the surface of the seamless belt is deformed due to heat generation of the polymer.

Japanese Patent No. 3671840 JP 2005-309227 A JP 2005-266760 A Japanese Patent No. 3821600 JP 2007-65587 A JP-A-57-212216

  The present invention is a conductive seamless belt manufactured by extrusion, which is a more preferable method in terms of cost than conventional thermosetting resin belts and rubber laminated belts, and has a durability, roller resistance, and elastic modulus of 3 An object of the present invention is to provide a conductive seamless belt having excellent performance.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have controlled the glass transition temperature and electron beam irradiation conditions of a polymer that irradiates an electron beam, thereby providing three physical properties of durability, roller resistance, and elastic modulus. In other words, the movement of the amorphous part of the polymer above the glass transition temperature can be achieved by irradiating an electron beam in a controlled state to the polymer having a specific glass transition temperature to moderately crosslink the electron beam. It has been found that the elastic modulus can be improved without impairing durability and roller resistance by restraining the property moderately.
The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

  The conductive seamless belt of the present invention (Claim 1) is a molding material obtained by heating and mixing a thermoplastic polymer component containing a polyester elastomer and a conductive agent, the main component being polyalkylene terephthalate and / or polyalkylene naphthalate. A seamless seamless belt obtained by irradiating an electron beam onto a seamless belt obtained by extrusion molding, wherein the glass transition temperature of the seamless belt irradiated with an electron beam is 0 ° C. or higher and 60 ° C. or lower, A total of 500 kGy or more and 1500 kGy or less of electron beams were irradiated under the condition of irradiation dose of 50 kGy or more and 100 kGy or less.

  The conductive seamless belt of claim 2 is characterized in that, in claim 1, 0.01 to 5.0 parts by weight of a crosslinking agent is blended in the molding material with respect to 100 parts by weight of the thermoplastic polymer component. Features.

  According to a third aspect of the present invention, there is provided the conductive seamless belt according to the second aspect, wherein the crosslinking agent is impregnated into a powder component of the raw material to be heated and mixed.

  According to a fourth aspect of the present invention, there is provided the conductive seamless belt according to the second or third aspect, wherein the crosslinking agent is an allylic polyfunctional monomer.

  A conductive seamless belt according to a fifth aspect is the belt for an image forming apparatus according to any one of the first to fourth aspects.

  An image forming apparatus according to a sixth aspect of the present invention includes the conductive seamless belt according to any one of the first to fifth aspects.

  According to the present invention, it is possible to realize a conductive seamless belt having high folding resistance, excellent roller wrinkle restoration rate, and high elasticity.

It is a side view of a general intermediate transfer device. It is a figure which shows the measurement chart of glass transition temperature.

  Hereinafter, embodiments of the conductive seamless belt and the image forming apparatus of the present invention will be described in detail.

  In the present invention, a molding material obtained by heat-mixing a thermoplastic polymer component containing polyalkylene terephthalate (PAT) and / or polyalkylene naphthalate (PAN) containing polyester elastomer (TPEE) and a conductive agent. A seamless belt having a specific glass transition temperature obtained by extrusion molding is irradiated with an electron beam under specific conditions to perform electron beam crosslinking.

  Generally, the electron dose irradiated in the electron beam cross-linking with respect to the resin is preferably 20 kGy or more and 300 kGy or less. In addition, PAT and PAN having a glass transition temperature of 0 ° C. or higher have a high aromatic ring content ratio in the polymer chain, so that electron beam crosslinking is difficult to proceed. However, in the present invention, TPEE is polymer blended with PAT and / or PAN to reduce the ratio of aromatic rings, and the total electron dose is 500 kGy or more and 1500 kGy under the condition of electron dose of 50 kGy or more and 100 kGy or less per time. By irradiating with an electron beam a plurality of times as described below, electron beam crosslinking is allowed to proceed without polymer collapse, and a seamless belt having a desired elastic modulus is obtained. As a result, it is possible to obtain a seamless belt excellent in all of durability, roller resistance, and elastic modulus, which are required characteristics of a seamless belt as an image forming apparatus belt.

  The molding material in the present invention preferably contains a crosslinking agent in addition to the thermoplastic polymer component and the conductive agent, and may contain an antioxidant and other components depending on the required performance. .

[Thermoplastic polymer component]
The thermoplastic polymer component according to the present invention is mainly composed of PAT and / or PAN and further contains TPEE.

  As polyalkylene terephthalate (PAT), polybutylene terephthalate (PBT), polyethylene terephthalate (PET) or the like can be suitably used. These resins are readily available in the market. For example, PBT is “Novaduran 5050cs” manufactured by Mitsubishi Engineering Plastics, and PET is “Novapex GM700Z” manufactured by Mitsubishi Chemical Corporation. Can be used.

  Moreover, as polyalkylene naphthalate (PAN), polybutylene naphthalate (PBN), polyethylene naphthalate (PEN), etc. can be used suitably. These resins are easily available in the market. For example, “TQB-OT” manufactured by Teijin Chemicals Ltd. is used as PBN, and “Teonex TN8065S” manufactured by Teijin Chemicals Ltd. is used as PEN. be able to.

  Among these, in particular, PBT and PBN have a crystallinity of about 30% higher than that of other PATs and PANs, so that the obtained seamless belt roller has a lower crystallinity than when PET or PEN is used.癖 High restoration rate is preferable.

  Polyester elastomers (TPEE) are polyester-polyester elastomer type using polyester for hard segment and polyester for soft segment, and polyester-polyether type using polyester for hard segment and polyether for soft segment. It can be used suitably. These elastomers are easily available in the market. Examples of polyester-polyester elastomers include “Perprene S3001” and “Perprene EN3000” manufactured by Toyobo Co., Ltd., and examples of polyester-polyether elastomers are manufactured by Toyobo Co., Ltd. “Perprene P150B” or the like can be used. These elastomers may be used alone or in combination of two or more.

  The ratio of PAT and / or PAN and TPEE in the thermoplastic polymer component can be set according to the purpose of use, but if there is too much TPEE, the change in the circumference of the seamless belt before and after electron beam irradiation, Since the resistance value change becomes large, it is necessary to have PAT and / or PAN as a main component, and the weight ratio of (PAT and / or PAN) / TPEE is 50/50 to 95/05, particularly 60/40 to 80 / 20 is preferable.

[Conductive agent]
The conductive agent is not particularly limited as long as it satisfies the performance required for the application, and various types can be used. Specifically, examples of the conductive filler include carbon black, carbon fiber, and graphite. Carbon-based fillers, metal-based conductive fillers, metal-oxide-based conductive fillers, and the like are used. Besides conductive fillers, ionic conductive substances such as quaternary ammonium salts are exemplified. Among the agents, it is preferable to use carbon black because the humidity dependency of the electrical resistivity tends to be reduced. Carbon black may be used in combination with an ion conductive substance.
Carbon black, which is a conductive filler, is mixed in consideration of mechanical characteristics, electrical characteristics, dimensional characteristics, and chemical characteristics when a seamless belt is formed.

  The blending amount of the conductive agent such as carbon black is preferably 10 to 30 parts by weight, particularly 12 to 17 parts by weight with respect to 100 parts by weight of the thermoplastic polymer component. That is, the blending amount of the conductive agent such as carbon black varies depending on the type of the conductive agent used and the degree of conductivity required for the seamless belt, but if the blending amount is too small, the conductivity may not be expressed, The electrical conductivity is likely to vary due to the dispersion state of the conductive agent, etc., and the contact resistance is greatly affected by the environment. When mounted on an image forming device, abnormal images may occur depending on the environment. There is a case to let you. On the other hand, if the blending amount of the conductive agent is too large, the rigidity of the seamless belt increases, durability is impaired, and moldability is impaired.

  The carbon black is preferably a powder product or a granular product, and the powder is preferably uniform. Carbon black that has been subjected to silicone treatment in advance may also be used.

[Crosslinking agent]
In the present invention, the electron beam cross-linking can be progressed by making the electron beam irradiation conditions appropriate without using a cross-linking agent. May be used. The cross-linking agent is not particularly limited as long as it can cause the cross-linking reaction of the thermoplastic polymer component by electron beam irradiation, but an allylic polyfunctional monomer is preferably used. Examples of the allylic polyfunctional monomer include one or more of triallyl isocyanurate (TAIC), triallyl cyanurate, and trimethallyl isocyanurate. Among them, TAIC can be preferably used. . Among allyl multi-component monomers, those having an epoxy group or a glycidyl group are not preferable because they are thermally crosslinked by heat during kneading and extrusion molding.

The blending amount of the crosslinking agent is preferably 5.0 parts by weight or less, for example, 0.01 to 5.0 parts by weight with respect to 100 parts by weight of the thermoplastic polymer component.
If the blending amount of the cross-linking agent is too small, the effect of promoting electron beam cross-linking due to the use of the cross-linking agent cannot be sufficiently obtained. It becomes worse and the elastic modulus is lowered, which is not preferable.

[Additional ingredients (optional ingredients)]
In the molding material according to the present invention, arbitrary blending components can be blended according to various purposes.

  Specifically, irgafos 168, irganox 1010, antioxidants such as phosphorus antioxidants, heat stabilizers, various plasticizers, light stabilizers, ultraviolet absorbers, neutralizers, lubricants, antifogging agents, anti Various additives such as a blocking agent, a slip agent, a crosslinking aid, a colorant, a flame retardant, and a dispersant can be added.

In particular, the addition of an antioxidant can prevent a decrease in folding resistance due to thermal degradation, but the target number of folding times can also be satisfied without the addition.
When adding antioxidant, it is preferable that the compounding quantity shall be about 0.01-5.0 weight part with respect to 100 weight part of thermoplastic polymer components in a molding material.

[Heating and mixing method]
In the present invention, the thermoplastic polymer component and a conductive agent such as carbon black may be heated and mixed to obtain a resin composition, and then a seamless belt may be formed. The thermoplastic polymer component and the conductive agent such as carbon black may be heated. A seamless belt may be formed as it is after mixing.

  There is no particular limitation on the heating and mixing means, and a known technique can be used. For example, if a thermoplastic polymer component, a conductive agent such as carbon black, and other additive components blended as needed are heated and mixed to form a resin composition, a single screw extruder, twin screw kneading extruder , Banbury mixers, rolls, Brabenders, plastographs, kneaders and the like can be used, and a twin-screw kneading extruder is particularly preferable.

  In this heating and mixing, since the above-mentioned crosslinking agent is usually in a liquid state, in order to prevent volatilization at the time of heating and mixing, it is impregnated with a powder component such as a preliminarily ground polymer component or a conductive agent such as carbon black and mixed. Is preferred.

[Extrusion molding method]
The extrusion molding method for molding the seamless belt of the present invention is not particularly limited, but a continuous melt extrusion molding method is particularly desirable. In particular, the internal cooling mandrel method or vacuum sizing method of the downward extrusion method capable of controlling the inner diameter of the extruded tube with high accuracy is preferable, and the internal cooling mandrel method is most preferable.

[Glass transition temperature of seamless belt]
In the present invention, a seamless belt obtained by heating and mixing the thermoplastic polymer component, a conductive agent such as carbon black, and other components blended as necessary, such as a crosslinking agent, and extrusion molding. The glass transition temperature is 0 ° C. or higher and 60 ° C. or lower.

  The glass transition temperature in the present invention is a cross-linking agent blended as necessary with a conductive agent such as carbon black in a thermoplastic polymer component which is a polymer blend with PAT and / or TPEE mainly composed of PAN, It is the glass transition temperature of the seamless belt before electron beam irradiation obtained by blending the ingredients, heating and mixing, and extrusion molding. PAT, PAN, and TPEE as raw materials themselves have a glass transition temperature outside the range of 0 to 60 ° C. There may be.

  The glass transition temperature of this seamless belt is a frequency of 10.0 Hz using a dynamic viscoelasticity measuring device “RSAIII” manufactured by TI Instruments, as described in the Examples section below. This refers to the peak temperature of α dispersion of tan δ under conditions of a heating rate of 2 ° C./min and a tensile strain of 0.05%.

In the present invention, when the glass transition temperature of the seamless belt before electron beam irradiation is less than 0 ° C., the elastic modulus before crosslinking by electron beam irradiation is low, so even if electron beam crosslinking is performed, the target elastic modulus It is difficult to reach and is not preferable. Further, even if the target elastic modulus is reached, it is not preferable because a change in electrical resistance value due to a large change in circumferential length before and after the crosslinking becomes large.
In addition, when the glass transition temperature of the seamless belt before the electron beam irradiation exceeds 60 ° C., the mobility of the polymer at room temperature to 60 ° C., which is the use temperature of the printer, is limited, and folding resistance is reduced. It is not preferable. Further, even when the glass transition temperature is 60 ° C. or lower, if the crystallinity is as low as about 10%, the folding resistance is increased, but the roller resistance is deteriorated. Moreover, even if PAT and PAN satisfying the folding resistance and roller resistance at a glass transition temperature of 60 ° C. or lower can be realized, the glass transition temperature exceeding 60 ° C. means that the benzene ring or naphthalene ring in the polymer chain Therefore, it is difficult to obtain a crosslinking effect by electron beam irradiation.

  The more preferable glass transition temperature of the seamless belt before electron beam irradiation is 30 to 60 ° C., and the crystallinity is 20 to 60%. There are various measuring methods for crystallinity, for example, the density of a seamless belt measured using a dry densitometer and the theoretical density value in the case of 100% crystallinity of each polymer used obtained from literature values. Can be used to calculate the approximate value from the ratio.

  In the present invention, the glass transition temperature of the seamless belt before electron beam irradiation is 0 to 60 ° C., preferably 30 to 60 ° C. The glass transition temperature of the seamless belt depends on the selection of the polymer or the blending ratio. It can be adjusted by controlling. That is, if the aromatic ring content ratio of the thermoplastic polymer component is increased or the blending ratio of PAT and / or PAN in the thermoplastic polymer component is increased, the glass transition temperature of the seamless belt before electron beam irradiation is increased. Become. Conversely, if the aromatic ring content in the thermoplastic polymer component is reduced or the PAT and / or PAN content in the thermoplastic polymer component is reduced, the glass transition of the seamless belt before electron beam irradiation. The temperature rises.

[Electron beam irradiation]
In the present invention, an electron beam with an irradiation dose of 50 kGy or more and 100 kGy or less is applied to the seamless belt having the specific glass transition temperature described above, and the electron beam irradiation is performed so that the total irradiation dose is 500 kGy or more and 1500 kGy or less. To carry out electron beam crosslinking.

  Here, if the irradiation dose per time is less than 50 kGy, it is necessary to increase the number of times of irradiation for sufficiently proceeding with the electron beam cross-linking, and if it exceeds 100 kGy, the seamless belt may be deteriorated by the electron beam irradiation. Is not preferable.

  In addition, when the total irradiation dose is less than 500 kGy, the electron beam crosslinking does not proceed sufficiently, and the intended elastic modulus cannot be obtained. If the irradiation dose exceeds 1500 kGy, the seamless belt may be deteriorated by electron beam irradiation.

  Particularly preferable irradiation conditions are such that an electron beam irradiation of 50 to 70 kGy per irradiation is repeatedly performed 10 to 20 times so that the total irradiation dose becomes 500 to 1400 kGy.

Here, when irradiating the electron beam, the electron beam irradiation device is rotated to rotate the cylinder that supports the seamless belt, so that the entire seamless belt is uniformly irradiated with the electron beam, and uniform electron beam crosslinking proceeds. It is preferable to do so.
In addition, even if the seamless belt shrinks during electron beam crosslinking, there is a gap (air layer) for shrinkage inside the seamless belt so that cracks do not occur due to tension caused by a metal support cylinder inserted inside. Preferably, it is provided and attached to the support cylinder.

In addition, the glass transition temperature of a seamless belt rises by electron beam irradiation. In the present invention, a seamless belt having a glass transition temperature of 0 to 60 ° C. is irradiated with an electron beam under the above-described conditions. The glass transition temperature is 30 to 80 ° C., and the difference in the glass transition temperature before and after the electron beam irradiation is 3 to 3. Obtaining a conductive seamless belt at 40 ° C. is preferable in terms of electrical resistance value control and circumference control.
Moreover, although the surface resistance value mentioned later changes by irradiation of an electron beam, it is preferable that the surface resistance value change rate described in the item of the below-mentioned Example is 0.5-2.0.

[Conductive seamless belt]
According to the present invention, a conductive seamless belt having the following physical properties can be obtained.

<Folding resistance>
When the conductive seamless belt of the present invention is used in an image forming apparatus as an intermediate transfer belt, for example, if the folding resistance is poor, a crack occurs and an image cannot be obtained.
The degree of folding resistance can be quantitatively evaluated by following the method of measuring the folding endurance of JIS P-8115, and it is judged that the seamless belt having the larger folding endurance is less susceptible to cracking and has excellent bending resistance. be able to.
As specific numerical values, the folding endurance measured by the measuring method described in the Examples section below is preferably 10,000 times or more, particularly preferably 100,000 times or more.
In the examples described later, the rotation radius (R) of the chuck to be used was set to 3.0 mm in order to approach the conditions in the case where the roller was actually stretched and rotated in the printer.

<Roller wrinkle restoration rate>
When the conductive seamless belt of the present invention is used as an intermediate transfer belt in an image forming apparatus, for example, the roller is applied to the seamless belt when the belt is placed at a high temperature of about 60 ° C. while being stretched around the roller in the printer. If the mark (roller wrinkle) arrives, the image will be adversely affected.
Therefore, a seamless belt that has been conditioned for 24 hours or more under conditions of a temperature of 23 ° C. and a humidity of 50% is cut into a 15 mm width and a 44 mm length, and this test piece is turned into a roller having a diameter of 14 mm and the length direction of the test piece is the circumference of the roller. Fix it with cellophane tape or the like so that it is in the direction, leave it in a constant temperature and humidity layer at a temperature of 60 ° C. and a humidity of 95% for 2 hours, and leave it in an environment of a temperature of 23 ° C. and a humidity of 50% for 24 hours. From the opening width L of the test piece when left for 2 hours at a temperature of 23 ° C. and a humidity of 50% after being released from the roller (the width of the opening of the test piece brazed into a substantially C-shaped cross section by the roller), Let the calculated value be the roller wrinkle restoration rate (%). This value is preferably 40% or more.
Roller wrinkle restoration rate (%) = {opening width L (mm) / test piece length 44 (mm)} × 100

<Crystallinity>
The smaller the change in crystallinity at the roller wrinkle test temperature, the higher the roller wrinkle restoration rate tends to be. In general, the higher the crystallinity of a polymer, the smaller the change in crystallinity at the roller wrinkle test temperature. Even if the degree of crystallinity is too high, the number of folding times is reduced.
Therefore, as PAT and PAN of the thermoplastic polymer component, PBT and PBN, which are generally considered to have a high degree of crystallinity, than PET and PEN, which are generally considered to have a low degree of crystallinity. Can also be preferably used.

<Tensile modulus>
When the conductive seamless belt of the present invention is used as an intermediate transfer belt in an image forming apparatus, for example, if the seamless belt has a low tensile elastic modulus, the surface hardness is lowered, and the surface of the transfer belt is caused by silica components contained in the toner. Is likely to cause image defects, so that a higher tensile elastic modulus is preferable.
For this reason, in accordance with ISO R1184-1970, for a test piece having a width of 15 mm and a length of 150 mm cut from the seamless belt of the present invention, the tensile modulus measured as a tensile speed of 1 mm / min and a gripping distance of 100 mm It is preferable that it is 1800 MPa or more.

<Micro hardness>
When the conductive seamless belt of the present invention is used as an intermediate transfer belt in an image forming apparatus, for example, if the seamless belt has a low micro hardness, the surface of the transfer belt may be scraped, causing image defects. Also, if the microhardness is low, the toner is likely to be buried in the surface of the intermediate transfer belt and the secondary transferability is deteriorated, which may cause image defects. On the other hand, if the microhardness is too high, cracks are likely to occur, and the mechanical life of the seamless belt is shortened.
For this reason, the degree of microhardness of the conductive seamless belt of the present invention is determined by using a microscope hardness meter HM2000 manufactured by Fischerscope, and measured with a HUPl (universal hardness plastic hardness) measured under conditions of an indentation load of 2.5 mN and an indentation time of 27 seconds. it is preferable 200 N / mm ² or more 400 N / mm ² or less in the value of is).

<Creep strain>
When the conductive seamless belt of the present invention is used as an intermediate transfer belt in an image forming apparatus, for example, if the creep distortion of the seamless belt is large, the transfer belt is stretched, resulting in poor dimensional accuracy and the cause of image defects. It may become.
Therefore, the degree of creep strain is 40 seconds when a load of 600 g is applied to a sample having a width of 20 mm, a length between chucks of 100 mm, and a thickness of 100 μm at a temperature condition of 60 ° C. The value calculated from the subsequent elongation length is preferably 0.05% or less.

<Surface resistance value>
The resistance region of the conductive seamless belt of the present invention varies depending on the purpose of use, but is preferably selected from the range of a surface resistance value of 1 × 10 ⁸ to 1 × 10 ¹⁶ Ω / □.
Here, the surface resistance value of the seamless belt can be measured by, for example, Hiresta manufactured by Mitsubishi Chemical Analytech Co., Ltd. Details of the method for measuring the surface resistance value are given in the Examples section below.

<Thickness of seamless belt>
The thickness of the conductive seamless belt of the present invention is preferably 60 to 150 μm, and is appropriately determined within this range depending on the purpose of use.

[Use of conductive seamless belt]
The conductive seamless belt of the present invention is used in an image forming apparatus such as an electrophotographic copying machine, a laser beam printer, and a facsimile machine as an intermediate transfer belt, a transfer transfer belt, a photosensitive belt, and the like. The conductive seamless belt of the present invention may be used as it is, or may be wound around a drum or a roll.
Further, for the purpose of preventing meandering or reinforcing the end surface, a heat-resistant tape is affixed to the inside and / or the vicinity of the outside edge of a seamless belt of a predetermined size, or a tape such as urethane rubber or silicone rubber is attached to the inside edge of the belt. They may be used in the vicinity of the part.

  The effects of the present invention will be described below with reference to examples and comparative examples.

[material]
The following materials were used, and the blending ratios were as shown in Tables 1 and 2.
・ PBT: Made by Mitsubishi Engineering Plastics
"Novaduran 5050CS"
・ PBN: "TQB-OT" manufactured by Teijin Chemicals Ltd.
・ PET: “Novapex GM700Z” manufactured by Mitsubishi Chemical Corporation
・ PEN: “Teonex TN8065S” manufactured by Teijin Chemicals Ltd.
・ Polyester elastomer (TPEE): "Perprene S3001" manufactured by Toyobo Co., Ltd.
・ Polyester elastomer (TPEE): “Perprene P150B” manufactured by Toyobo Co., Ltd.
・ Polyester elastomer (TPEE): “Perprene EN3000” manufactured by Toyobo Co., Ltd.
・ Carbon black: Acetylene black “Denka Black granular” manufactured by Electrochemical Co., Ltd.
・ Antioxidant: "PEPQ" manufactured by Clariant Japan
・ Crosslinking agent: “TAIC” (triallyl isocyanurate) manufactured by Nippon Kasei Co., Ltd.
・ Crosslinking agent: “DA-MGIC” manufactured by Shikoku Kasei Co., Ltd.
(Diallyl monoglycidyl isocyanuric acid)

[Heat kneading]
Each raw material was pelletized using a twin-screw kneading extruder (PMG32 manufactured by IKG Co., Ltd.). The cross-linking agent “TAIC” is a liquid having a boiling point of about 144 ° C., and since it easily volatilizes when added in a liquid state during kneading, it was pre-impregnated with carbon black and then blended and kneaded.
The extruder is L / D = 32, 2 vent type, kneading is arranged on the material input side from each vent, the discharge rate of polymer is 14 kg / hr, and the cylinder temperature is from the cylinder closest to the hopper. The cylinder up to the inlet side vented is 250 ° C., the others are 200 ° C., the rotation speed is 140 rpm, the discharged molten polymer is made into a strand shape, passed through a water tank, and then pelletized to a predetermined Size pellets were made.

[Extrusion molding]
The pellets were dried at 130 ° C. for 6 hours, extruded in a molten tube state below the annular die by an extruder with a diameter of 184 mm, a die-slip width of 1.0 mm and a 6 mm spiral annular die and extruded into a molten tube state. A cylindrical core installed in a seamless belt while contacting and cooling and solidifying the outer surface (temperature 90 ° C.) of the cooling mandrel mounted on the same axis as the annular die via a support rod With a four-point belt take-up machine installed on the outside, the seamless belt is taken up while being held in a cylindrical shape, and is cut into a length of 300 mm, with a thickness of 100 μm and a surface resistance value of 1 × 10 ⁸ to 1 take-off speed and the extrusion rate so as × become 10 ¹³ Ω / □, by adjusting the extrusion temperature, a cylinder temperature and a die temperature of 240 ° C., seamless Bell It was molded.

[Electron beam irradiation]
Electron beam irradiation was performed under the irradiation conditions shown in Tables 1 and 2 using an electron beam irradiation apparatus EPS-750 kV manufactured by NHV Corporation. In the table, the unit irradiation dose is the irradiation dose per time, and the total irradiation dose is the total irradiation dose. The electron beam was irradiated back and forth on a metal plate having a width of 120 cm and a length of 80 cm at an irradiation width of 120 cm and an irradiation speed of 1.2 m / min, and the number of irradiations per one way was defined as the number of irradiations. . In addition, the seamless belt is supported on the outer circumference of a metal cylinder, installed in parallel on the metal plate of the device, and manually rotated by a quarter of the circumference every quarter of the total number of irradiations. As a result, the electron beam cross-linking proceeded uniformly throughout the seamless belt.
Also, in order to prevent cracks from occurring due to the metal cylinder inserted inside the seamless belt even when it is shrunk during cross-linking, a cylinder (air layer) for shrinkage is provided inside the seamless belt. Supported.

[Evaluation]
The evaluation was carried out by opening the seamless belt to the required size as required.

<Glass transition temperature>
Using a dynamic viscoelasticity measuring device “RSAIII” manufactured by TI Instruments, a seamless belt before and after electron beam irradiation has a frequency of 10.0 Hz, a heating rate of 2 ° C./min, and a tensile strain of 0.05%. The peak temperature of tan δ measured under the conditions was defined as the glass transition temperature. This measurement chart is shown in FIG.

<Folding resistance>
In accordance with JIS P-8115, a test piece cut to a size of 15 mm in width and 100 mm in length from a seamless belt after irradiation with an electron beam was subjected to a bending speed of 175 times / min with a MIT test machine, a rotation angle of 135 ° left and right, Under the conditions of a tensile load of 1.0 kgf and a distance between chucks of 50 mm, the number of bendings to breakage was measured with the chuck turning radius of R = 3.0 mm.

<Roller wrinkle restoration rate>
After the electron beam irradiation, the seamless belt was conditioned for 24 hours or more at a temperature of 23 ° C. and a humidity of 50%. Then, a test piece having a width of 15 mm and a length of 44 mm was cut out from the seamless belt, and a cellophane tape, etc. After being left in a constant temperature and humidity layer having a temperature of 60 ° C. and a humidity of 95% for 2 hours, and then allowed to stand in an environment of a temperature of 23 ° C. and a humidity of 50% for 24 hours, the test piece is released from the roller, and the temperature is 23 ° C. The roller wrinkle restoration rate (%) was calculated from the opening width (L) of the test piece when left for 2 hours at a humidity of 50% by the following formula.
Roller wrinkle restoration rate (%) = {opening width L (mm) / sample length 44 (mm)} × 100

<Tensile modulus>
In accordance with ISO R1184-1970, a test piece having a width of 15 mm and a length of 150 mm cut from a seamless belt after irradiation with an electron beam was measured at a tensile speed of 1 mm / min and a gripping tool distance of 100 mm.

<Micro hardness>
Using a microhardness meter “HM2000” manufactured by Fischerscope, HUpl (universal hardness plastic hardness) was measured under conditions of an indentation load of 2.5 mN and an indentation time of 27 seconds.

<Creep strain>
From a test piece with a width of 20 mm cut out from a seamless belt after irradiation with an electron beam, the following is obtained from the elongation length (Z) after 40 seconds when a load of 600 g is applied under a temperature condition of 100 mm between chucks and 60 ° C. It was calculated by the following formula.
Creep strain εt = (Z-100) / 100

<Change rate of surface resistance value>
Using a Hiresta (HA terminal) manufactured by Mitsubishi Chemical Analytech Co., Ltd., and measuring the circumferential direction of the belt at a pitch of 20 mm under a condition of 500 V for 10 seconds on a seamless belt before and after electron beam irradiation, the surface resistance obtained The average value of the rate was defined as the surface resistance value. From the measured value of the surface resistance value before and after the electron beam irradiation, the ratio was calculated by the following formula to obtain the surface resistance value change rate.
Surface resistance value change rate (%)
= {Surface resistance value after electron beam irradiation / surface resistance value before electron beam irradiation} × 100

<Image evaluation>
The seamless belt after irradiation with the electron beam is mounted on a transfer belt unit of a tandem color laser printer having a roller having a diameter of 14 mm and left in an environment of a temperature of 60 ° C. and a humidity of 95% for 2 hours, and then a temperature of 23 ° C. and a humidity of 50 %, Then the transfer belt unit was mounted on a printer, and the output black solid image was visually observed and evaluated according to the following criteria.
○: No white spots can be confirmed visually. Δ: White spots can be confirmed by staring visually, but there is no problem. ×: White spots are noticeable and problematic.

  The evaluation results are shown in Tables 1 and 2.

[Discussion]
<Examples 1-6>
With the blending of PBT / S3001N = 7/3 (weight ratio), the addition amount of the crosslinking agent TAIC is 0 to 5% by weight with respect to the thermoplastic polymer component, and the electron beam irradiation is performed 10 to 15 times at 50 to 100 kGy per time. However, it is preferable because the number of folding times is 100,000 times or more, the roller wrinkle restoration rate is 40% or more, the tensile elastic modulus is 1800 MPa or more, and the change in the surface resistance value is small.

<Examples 7 to 10>
This is an example in which the compounding of PAT / TPEE or PAN / TPEE was changed and electron beam irradiation was performed. The folding number of times was 100,000 times or more, the roller wrinkle restoration rate was 40% or more, and the tensile modulus was 1800 MPa or more. And the change in the surface resistance value is small, which is preferable.

<Comparative Examples 1-2>
Although it is an example in which electron beam irradiation was performed on PAT or PAN alone, since the glass transition temperature before electron beam irradiation is higher than 60 ° C., the mobility of the amorphous part of the polymer after electron beam irradiation is Since it is further suppressed, folding resistance is low. Further, since it is in the transition state within the measurement range of the roller wrinkle restoration rate, it is easily recrystallized and the roller wrinkle restoration rate is poor.

<Comparative Examples 3-7>
Although it is an example which changed the electron beam irradiation conditions with respect to Examples 1 and 3, since the comparative examples 3 and 4 are not implementing electron beam irradiation, the tensile elasticity modulus is low. In Comparative Example 5, since the number of times of electron beam irradiation is insufficient, crosslinking does not proceed sufficiently and the tensile modulus is low. Since the comparative example 6 has too many electron beam irradiations, disintegration progresses and the number of folding times is low. In Comparative Example 7, since the electron beam irradiation was performed at a high irradiation dose as high as 300 kGy at a time, the number of folding times was low because the polymer was deteriorated due to high heat.

<Comparative Example 8>
Although it is an example using allylic crosslinking agent DA-MGIC having a glycidyl group as a crosslinking agent, since it has a glycidyl group, thermal crosslinking proceeds during kneading and molding, and kneading and molding become impossible. It is not preferable.

<Comparative Example 9>
Since TPEE is the main component, the glass transition temperature before cross-linking is −10 ° C., which is lower than 0 ° C. However, the tensile elastic modulus after cross-linking is low, so the tensile elastic modulus after cross-linking does not reach the target. It is not preferable.

<Comparative Example 10>
TPEE is the main component, and the glass transition temperature before cross-linking is 41 ° C. The folding number of times, roller wrinkle restoration rate, and tensile elastic modulus have reached the target, but the degree of progress of cross-linking is large, Since the change is large, the change of the surface resistance value becomes large, which is not preferable.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charging device 3 Exposure optical system 4 Developer 5 Cleaner 6 Conductive endless belt 7, 8, 9 Conveyance roller

Claims (6)

An electron beam is applied to a seamless belt obtained by extruding a molding material comprising a polyalkylene terephthalate and / or a polyalkylene naphthalate as a main component and a thermoplastic polymer component containing a polyester elastomer and a conductive agent. A conductive seamless belt formed by irradiation,
The glass transition temperature of the seamless belt irradiated with the electron beam is 0 ° C. or higher and 60 ° C. or lower,
A conductive seamless belt, wherein the seamless belt is irradiated with a total of 500 kGy or more and 1500 kGy or less of electron beams under an irradiation dose of 50 kGy or more and 100 kGy or less.   2. The conductive seamless belt according to claim 1, wherein 0.01 to 5.0 parts by weight of a crosslinking agent is blended in the molding material with respect to 100 parts by weight of the thermoplastic polymer component.   3. The conductive seamless belt according to claim 2, wherein the cross-linking agent is blended by impregnating a powder component of the raw material to be heated and mixed.   4. The conductive seamless belt according to claim 2, wherein the crosslinking agent is an allylic polyfunctional monomer.   5. The conductive seamless belt according to claim 1, wherein the conductive seamless belt is an image forming apparatus belt.   An image forming apparatus comprising the conductive seamless belt according to claim 1.

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